Publications by authors named "Dino Di Carlo"

188 Publications

Development and validation of a cellular host response test as an early diagnostic for sepsis.

PLoS One 2021 15;16(4):e0246980. Epub 2021 Apr 15.

Louisiana State University Health Sciences Center, Baton Rouge, Louisiana, United States of America.

Sepsis must be diagnosed quickly to avoid morbidity and mortality. However, the clinical manifestations of sepsis are highly variable and emergency department (ED) clinicians often must make rapid, impactful decisions before laboratory results are known. We previously developed a technique that allows the measurement of the biophysical properties of white blood cells as they are stretched through a microfluidic channel. In this study we describe and validate the resultant output as a model and score-the IntelliSep Index (ISI)-that aids in the diagnosis of sepsis in patients with suspected or confirmed infection from a single blood draw performed at the time of ED presentation. By applying this technique to a high acuity cohort with a 23.5% sepsis incidence (n = 307), we defined specific metrics-the aspect ratio and visco-elastic inertial response-that are more sensitive than cell size or cell count in predicting disease severity. The final model was trained and cross-validated on the high acuity cohort, and the performance and generalizability of the model was evaluated on a separate low acuity cohort with a 6.4% sepsis incidence (n = 94) and healthy donors (n = 72). For easier clinical interpretation, the ISI is divided into three interpretation bands of Green, Yellow, and Red that correspond to increasing disease severity. The ISI agreed with the diagnosis established by retrospective physician adjudication, and accurately identified subjects with severe illness as measured by SOFA, APACHE-II, hospital-free days, and intensive care unit admission. Measured using routinely collected blood samples, with a short run-time and no requirement for patient or laboratory information, the ISI is well suited to aid ED clinicians in rapidly diagnosing sepsis.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0246980PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8049231PMC
April 2021

Single-Domain Multiferroic Array-Addressable Terfenol-D (SMArT) Micromagnets for Programmable Single-Cell Capture and Release.

Adv Mater 2021 Apr 8:e2006651. Epub 2021 Apr 8.

Department of Bioengineering, University of California, Los Angeles, Los Angeles, CA, 90095, USA.

Programming magnetic fields with microscale control can enable automation at the scale of single cells ≈10 µm. Most magnetic materials provide a consistent magnetic field over time but the direction or field strength at the microscale is not easily modulated. However, magnetostrictive materials, when coupled with ferroelectric material (i.e., strain-mediated multiferroics), can undergo magnetization reorientation due to voltage-induced strain, promising refined control of magnetization at the micrometer-scale. This work demonstrates the largest single-domain microstructures (20 µm) of Terfenol-D (Tb Dy Fe ), a material that has the highest magnetostrictive strain of any known soft magnetoelastic material. These Terfenol-D microstructures enable controlled localization of magnetic beads with sub-micrometer precision. Magnetically labeled cells are captured by the field gradients generated from the single-domain microstructures without an external magnetic field. The magnetic state on these microstructures is switched through voltage-induced strain, as a result of the strain-mediated converse magnetoelectric effect, to release individual cells using a multiferroic approach. These electronically addressable micromagnets pave the way for parallelized multiferroics-based single-cell sorting under digital control for biotechnology applications.
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http://dx.doi.org/10.1002/adma.202006651DOI Listing
April 2021

Injectable, macroporous scaffolds for delivery of therapeutic genes to the injured spinal cord.

APL Bioeng 2021 Mar 9;5(1):016104. Epub 2021 Mar 9.

Department of Bioengineering, University of California, Los Angeles, California 90095, USA.

Biomaterials are being developed as therapeutics for spinal cord injury (SCI) that can stabilize and bridge acute lesions and mediate the delivery of transgenes, providing a localized and sustained reservoir of regenerative factors. For clinical use, direct injection of biomaterial scaffolds is preferred to enable conformation to unique lesions and minimize tissue damage. While an interconnected network of cell-sized macropores is necessary for rapid host cell infiltration into-and thus integration of host tissue with-implanted scaffolds, injectable biomaterials have generally suffered from a lack of control over the macrostructure. As genetic vectors have short lifetimes , rapid host cell infiltration into scaffolds is a prerequisite for efficient biomaterial-mediated delivery of transgenes. We present scaffolds that can be injected and assembled from hyaluronic acid (HA)-based, spherical microparticles to form scaffolds with a network of macropores (∼10 m). The results demonstrate that addition of regularly sized macropores to traditional hydrogel scaffolds, which have nanopores (∼10 nm), significantly increases the expression of locally delivered transgene to the spinal cord after a thoracic injury. Maximal cell and axon infiltration into scaffolds was observed in scaffolds with more regularly sized macropores. The delivery of lentiviral vectors encoding the brain-derived neurotrophic factor (BDNF), but not neurotrophin-3, from these scaffolds further increased total numbers and myelination of infiltrating axons. Modest improvements to the hindlimb function were observed with BDNF delivery. The results demonstrate the utility of macroporous and injectable HA scaffolds as a platform for localized gene therapies after SCI.
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http://dx.doi.org/10.1063/5.0035291DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7946441PMC
March 2021

Injectable Drug-Releasing Microporous Annealed Particle Scaffolds for Treating Myocardial Infarction.

Adv Funct Mater 2020 Oct 6;30(43). Epub 2020 Sep 6.

Department of Bioengineering, University of California, Los Angeles, CA 90095, USA.

Intramyocardial injection of hydrogels offers great potential for treating myocardial infarction (MI) in a minimally invasive manner. However, traditional bulk hydrogels generally lack microporous structures to support rapid tissue ingrowth and biochemical signals to prevent fibrotic remodeling toward heart failure. To address such challenges, a novel drug-releasing microporous annealed particle (drugMAP) system is developed by encapsulating hydrophobic drug-loaded nanoparticles into microgel building blocks via microfluidic manufacturing. By modulating nanoparticle hydrophilicity and pregel solution viscosity, drugMAP building blocks are generated with consistent and homogeneous encapsulation of nanoparticles. In addition, the complementary effects of forskolin (F) and Repsox (R) on the functional modulations of cardiomyocytes, fibroblasts, and endothelial cells in vitro are demonstrated. After that, both hydrophobic drugs (F and R) are loaded into drugMAP to generate FR/drugMAP for MI therapy in a rat model. The intramyocardial injection of MAP gel improves left ventricular functions, which are further enhanced by FR/drugMAP treatment with increased angiogenesis and reduced fibrosis and inflammatory response. This drugMAP platform represents a new generation of microgel particles for MI therapy and will have broad applications in regenerative medicine and disease therapy.
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http://dx.doi.org/10.1002/adfm.202004307DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7942842PMC
October 2020

Magnetic microparticle concentration and collection using a mechatronic magnetic ratcheting system.

PLoS One 2021 18;16(2):e0246124. Epub 2021 Feb 18.

California NanoSystems Institute, Los Angeles, California, United States of America.

Magnetic ratcheting cytometry is a promising approach to separate magnetically-labeled cells and magnetic particles based on the quantity of magnetic material. We have previously reported on the ability of this technique to separate magnetically-labeled cells. Here, with a new chip design, containing high aspect ratio permalloy micropillar arrays, we demonstrate the ability of this technique to rapidly concentrate and collect superparamagnetic iron oxide particles. The platform consists of a mechatronic wheel used to generate and control a cycling external magnetic field that impinges on a "ratcheting chip." The ratcheting chip is created by electroplating a 2D array of high aspect ratio permalloy micropillars onto a glass slide, which is embedded in a thin polymer layer to create a planar surface above the micropillars. By varying magnetic field frequency and direction through wheel rotation rate and angle, we direct particle movement on chip. We explore the operating conditions for this system, identifying the effects of varying ratcheting frequency, along with time, on the dynamics and resulting concentration of these magnetic particles. We also demonstrate the ability of the system to rapidly direct the movement of superparamagnetic iron oxide particles of varying sizes. Using this technique, 2.8 μm, 500 nm, and 100 nm diameter superparamagnetic iron oxide particles, suspended within an aqueous fluid, were concentrated. We further define the ability of the system to concentrate 2.8 μm superparamagnetic iron oxide particles, present in a liquid suspension, into a small chip surface area footprint, achieving a 100-fold surface area concentration, and achieving a concentration factor greater than 200%. The achieved concentration factor of greater than 200% could be greatly increased by reducing the amount of liquid extracted at the chip outlet, which would increase the ability of achieving highly sensitive downstream analytical techniques. Magnetic ratcheting-based enrichment may be useful in isolating and concentrating subsets of magnetically-labeled cells for diagnostic automation.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0246124PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7891735PMC
February 2021

Selective and Improved Photoannealing of Microporous Annealed Particle (MAP) Scaffolds.

ACS Biomater Sci Eng 2021 02 6;7(2):422-427. Epub 2021 Jan 6.

Department of Biomedical Engineering, University of Virginia, Charlottesville, Virginia 22904, United States.

Microporous annealed particle (MAP) scaffolds consist of a slurry of hydrogel microspheres that undergo annealing to form a solid scaffold. MAP scaffolds have contained functional groups with dual abilities to participate in Michael-type addition (gelation) and radical polymerization (photoannealing). Functional groups with efficient Michael-type additions react with thiols and amines under physiological conditions, limiting usage for therapeutic delivery. We present a heterofunctional maleimide/methacrylamide 4-arm PEG macromer (MethMal) engineered for selective photopolymerization compatible with multiple polymer backbones. Rheology using two classes of photoinitiators demonstrates advantageous photopolymerization capabilities. Functional assays show benefits for therapeutic delivery and 3D printing without impacting cell viability.
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http://dx.doi.org/10.1021/acsbiomaterials.0c01580DOI Listing
February 2021

Engineering Design of Concentric Amphiphilic Microparticles for Spontaneous Formation of Picoliter to Nanoliter Droplet Volumes.

Anal Chem 2021 02 7;93(4):2317-2326. Epub 2021 Jan 7.

Department of Bioengineering, University of California, Los Angeles, Los Angeles, California 90095, United States.

Simple mixing of aqueous and oil solutions with amphiphilic particles leads to the spontaneous formation of uniform reaction volumes (dropicles) that can enable numerous applications in the analysis of biological entities (e.g., cells and molecules). Approaches to manufacture such amphiphilic particles are just starting to be investigated. Here, we investigate the tunable manufacturing of concentric amphiphilic particles, with outer hydrophobic and inner hydrophilic layers, fabricated by flowing reactive precursor streams through a 3D printed device with coaxial microfluidic channels, and curing the structured flow by UV exposure through a photomask. The dimensions of the engineered amphiphilic particles, including height, inner and outer diameters, and thicknesses of the hydrophobic and hydrophilic layers, are precisely controlled by modulating the UV exposure time, the precursor flow rate ratios, and the size of the channel in the exposure region. The particle design is systematically engineered to hold a wide range of droplet volumes, that is, from a few hundred picoliters to several nanoliters. We show that the particle size can be significantly reduced from previous reports to not only hold subnanoliter drops but the shape can also be tuned to increase the seeding density and orientation of dropicles within a well plate for imaging and analysis.
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http://dx.doi.org/10.1021/acs.analchem.0c04184DOI Listing
February 2021

Scanning two-photon continuous flow lithography for the fabrication of multi-functional microparticles.

Opt Express 2020 Dec;28(26):40088-40098

In this work, we demonstrate the high-throughput fabrication of 3D microparticles using a scanning two-photon continuous flow lithography (STP-CFL) technique in which microparticles are shaped by scanning the laser beam at the interface of laminar co-flows. The results demonstrate the ability of STP-CFL to manufacture high-resolution complex geometries of cell carriers that possess distinct regions with different functionalities. A new approach is presented for printing out-of-plane features on the microparticles. The approach eliminates the use of axial scanning stages, which are not favorable since they induce fluctuations in the flowing polymer media and their scanning speed is slower than the speed of galvanometer mirror scanners.
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http://dx.doi.org/10.1364/OE.410090DOI Listing
December 2020

Single Cell Mechanotype and Associated Molecular Changes in Urothelial Cell Transformation and Progression.

Front Cell Dev Biol 2020 19;8:601376. Epub 2020 Nov 19.

Department of Pathology and Laboratory Medicine, University of California, Los Angeles, Los Angeles, CA, United States.

Cancer cell mechanotype changes are newly recognized cancer phenotypic events, whereas metastatic cancer cells show decreased cell stiffness and increased deformability relative to normal cells. To further examine how cell mechanotype changes in early stages of cancer transformation and progression, an multi-step human urothelial cell carcinogenic model was used to measure cellular Young's modulus, deformability, and transit time using single-cell atomic force microscopy, microfluidic-based deformability cytometry, and quantitative deformability cytometry, respectively. Measurable cell mechanotype changes of stiffness, deformability, and cell transit time occur early in the transformation process. As cells progress from normal, to preinvasive, to invasive cells, Young's modulus of stiffness decreases and deformability increases gradually. These changes were confirmed in three-dimensional cultured microtumor masses and urine exfoliated cells directly from patients. Using gene screening and proteomics approaches, we found that the main molecular pathway implicated in cell mechanotype changes appears to be epithelial to mesenchymal transition.
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http://dx.doi.org/10.3389/fcell.2020.601376DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7711308PMC
November 2020

Activating an adaptive immune response from a hydrogel scaffold imparts regenerative wound healing.

Nat Mater 2021 04 9;20(4):560-569. Epub 2020 Nov 9.

Division of Dermatology, Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA, USA.

Microporous annealed particle (MAP) scaffolds are flowable, in situ crosslinked, microporous scaffolds composed of microgel building blocks and were previously shown to accelerate wound healing. To promote more extensive tissue ingrowth before scaffold degradation, we aimed to slow MAP degradation by switching the chirality of the crosslinking peptides from L- to D-amino acids. Unexpectedly, despite showing the predicted slower enzymatic degradation in vitro, D-peptide crosslinked MAP hydrogel (D-MAP) hastened material degradation in vivo and imparted significant tissue regeneration to healed cutaneous wounds, including increased tensile strength and hair neogenesis. MAP scaffolds recruit IL-33 type 2 myeloid cells, which is amplified in the presence of D-peptides. Remarkably, D-MAP elicited significant antigen-specific immunity against the D-chiral peptides, and an intact adaptive immune system was required for the hydrogel-induced skin regeneration. These findings demonstrate that the generation of an adaptive immune response from a biomaterial is sufficient to induce cutaneous regenerative healing despite faster scaffold degradation.
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http://dx.doi.org/10.1038/s41563-020-00844-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8005402PMC
April 2021

Monodisperse drops templated by 3D-structured microparticles.

Sci Adv 2020 Nov 4;6(45). Epub 2020 Nov 4.

Department of Bioengineering, University of California, Los Angeles, CA 90095, USA.

The ability to create uniform subnanoliter compartments using microfluidic control has enabled new approaches for analysis of single cells and molecules. However, specialized instruments or expertise has been required, slowing the adoption of these cutting-edge applications. Here, we show that three dimensional-structured microparticles with sculpted surface chemistries template uniformly sized aqueous drops when simply mixed with two immiscible fluid phases. In contrast to traditional emulsions, particle-templated drops of a controlled volume occupy a minimum in the interfacial energy of the system, such that a stable monodisperse state results with simple and reproducible formation conditions. We describe techniques to manufacture microscale drop-carrier particles and show that emulsions created with these particles prevent molecular exchange, concentrating reactions within the drops, laying a foundation for sensitive compartmentalized molecular and cell-based assays with minimal instrumentation.
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http://dx.doi.org/10.1126/sciadv.abb9023DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7673687PMC
November 2020

A review of biosensor technologies for blood biomarkers toward monitoring cardiovascular diseases at the point-of-care.

Biosens Bioelectron 2021 Jan 18;171:112621. Epub 2020 Sep 18.

Department of Bioengineering, University of California, Los Angeles, 420 Westwood Plaza, Los Angeles, CA, 90095, USA. Electronic address:

Cardiovascular diseases (CVDs) cause significant mortality globally. Notably, CVDs disproportionately negatively impact underserved populations, such as those that are economically disadvantaged and often located in remote regions. Devices to measure cardiac biomarkers have traditionally been focused on large instruments in a central laboratory but the development of affordable, portable devices that measure multiple cardiac biomarkers at the point-of-care (POC) are needed to improve clinical outcomes for patients, especially in underserved populations. Considering the enormity of the global CVD problem, complexity of CVDs, and the large candidate pool of biomarkers, it is of great interest to evaluate and compare biomarker performance and identify potential multiplexed panels that can be used in combination with affordable and robust biosensors at the POC toward improved patient care. This review focuses on describing the known and emerging CVD biosensing technologies for analysis of cardiac biomarkers from blood. Initially, the global burden of CVDs and the standard of care for the primary CVD categories, namely heart failure (HF) and acute coronary syndrome (ACS) including myocardial infarction (MI) are discussed. The latest United States, Canadian and European society guidelines recommended standalone, emerging, and add-on cardiac biomarkers, as well as their combinations are then described for the prognosis, diagnosis, and risk stratification of CVDs. Finally, both commercial in vitro biosensing devices and recent state-of-art techniques for detection of cardiac biomarkers are reviewed that leverage single and multiplexed panels of cardiac biomarkers with a view toward affordable, compact devices with excellent performance for POC diagnosis and monitoring.
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http://dx.doi.org/10.1016/j.bios.2020.112621DOI Listing
January 2021

Detection of EGFR Mutations in cfDNA and CTCs, and Comparison to Tumor Tissue in Non-Small-Cell-Lung-Cancer (NSCLC) Patients.

Front Oncol 2020 8;10:572895. Epub 2020 Oct 8.

Vortex Biosciences, Inc., Pleasanton, CA, United States.

Lung cancer is the leading cause of cancer-related mortality worldwide. Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) therapies, based on the evaluation of mutations, have shown dramatic clinical benefits. mutation assays are mainly performed on tumor biopsies, which carry risks, are not always successful and give results relevant to the timepoint of the assay. To detect secondary mutations, which cause resistance to 1st and 2nd generation TKIs and lead to the administration of a 3rd generation drug, effective and non-invasive monitoring of mutation status is needed. Liquid biopsy analytes, such as circulating tumor cells (CTCs) and circulating tumor DNA (cfDNA), allow such monitoring over the course of the therapy. The aim of this study was to develop and optimize a workflow for the evaluation of cfDNA and CTCs in NSCLC patients all from one blood sample. Using Vortex technology and EntroGen ctEGFR assay, mutations were identified at 0.5 ng of DNA (∼83 cells), with a sensitivity ranging from 0.1 to 2.0% for a total DNA varying from 25 ng (∼4 CTCs among 4000 white blood cells, WBCs) to 1 ng (∼4 CTCs among 200 WBCs). The processing of plasma-depleted-blood provided comparable capture recovery as whole blood, confirming the possibility of a multimodality liquid biopsy analysis (cfDNA and CTC DNA) from a single tube of blood. Different anticoagulants were evaluated and compared in terms of respective performance. Blood samples from 24 NSCLC patients and 6 age-matched healthy donors were analyzed with this combined workflow to minimize blood volume needed and sample-to-sample bias, and the mutation profile detected from CTCs and cfDNA was compared to matched tumor tissues. Despite the limited size of the patient cohort, results from this non-invasive mutation analysis are encouraging and this combined workflow represents a valuable means for informing therapy selection and for monitoring treatment of patients with NSCLC.
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http://dx.doi.org/10.3389/fonc.2020.572895DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7578230PMC
October 2020

A ferrobotic system for automated microfluidic logistics.

Sci Robot 2020 02;5(39)

Interconnected & Integrated Bioelectronics Lab (IBL), Department of Electrical and Computer Engineering, University of California, Los Angeles, CA, USA.

Automated technologies that can perform massively parallelized and sequential fluidic operations at small length scales can resolve major bottlenecks encountered in various fields, including medical diagnostics, -omics, drug development, and chemical/material synthesis. Inspired by the transformational impact of automated guided vehicle systems on manufacturing, warehousing, and distribution industries, we devised a ferrobotic system that uses a network of individually addressable robots, each performing designated micro-/nanofluid manipulation-based tasks in cooperation with other robots toward a shared objective. The underlying robotic mechanism facilitating fluidic operations was realized by addressable electromagnetic actuation of miniature mobile magnets that exert localized magnetic body forces on aqueous droplets filled with biocompatible magnetic nanoparticles. The contactless and high-strength nature of the actuation mechanism inherently renders it rapid (~10 centimeters/second), repeatable (>10,000 cycles), and robust (>24 hours). The robustness and individual addressability of ferrobots provide a foundation for the deployment of a network of ferrobots to carry out cross-collaborative logistics efficiently. These traits, together with the reconfigurability of the system, were exploited to devise and integrate passive/active advanced functional components (e.g., droplet dispensing, generation, filtering, and merging), enabling versatile system-level functionalities. By applying this ferrobotic system within the framework of a microfluidic architecture, the ferrobots were tasked to work cross-collaboratively toward the quantification of active matrix metallopeptidases (a biomarker for cancer malignancy and inflammation) in human plasma, where various functionalities converged to achieve a fully automated assay.
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http://dx.doi.org/10.1126/scirobotics.aba4411DOI Listing
February 2020

In situ forming microporous gelatin methacryloyl hydrogel scaffolds from thermostable microgels for tissue engineering.

Bioeng Transl Med 2020 Sep 2;5(3):e10180. Epub 2020 Sep 2.

Department of Bioengineering University of California, Los Angeles Los Angeles California USA.

Converting biopolymers to extracellular matrix (ECM)-mimetic hydrogel-based scaffolds has provided invaluable opportunities to design in vitro models of tissues/diseases and develop regenerative therapies for damaged tissues. Among biopolymers, gelatin and its crosslinkable derivatives, such as gelatin methacryloyl (GelMA), have gained significant importance for biomedical applications due to their ECM-mimetic properties. Recently, we have developed the first class of in situ forming GelMA microporous hydrogels based on the chemical annealing of physically crosslinked GelMA microscale beads (microgels), which addressed several key shortcomings of bulk (nanoporous) GelMA scaffolds, including lack of interconnected micron-sized pores to support on-demand three-dimensional-cell seeding and cell-cell interactions. Here, we address one of the limitations of in situ forming microporous GelMA hydrogels, that is, the thermal instability (melting) of their physically crosslinked building blocks at physiological temperature, resulting in compromised microporosity. To overcome this challenge, we developed a two-step fabrication strategy in which thermostable GelMA microbeads were produced via semi-photocrosslinking, followed by photo-annealing to form stable microporous scaffolds. We show that the semi-photocrosslinking step (exposure time up to 90 s at an intensity of ~100 mW/cm and a wavelength of ~365 nm) increases the thermostability of GelMA microgels while decreasing their scaffold forming (annealing) capability. Hinging on the tradeoff between microgel and scaffold stabilities, we identify the optimal crosslinking condition (exposure time ~60 s) that enables the formation of stable annealed microgel scaffolds. This work is a step forward in engineering in situ forming microporous hydrogels made up from thermostable GelMA microgels for in vitro and in vivo applications at physiological temperature well above the gelatin melting point.
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http://dx.doi.org/10.1002/btm2.10180DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7510466PMC
September 2020

Fabrication of 3D concentric amphiphilic microparticles to form uniform nanoliter reaction volumes for amplified affinity assays.

Lab Chip 2020 10 8;20(19):3503-3514. Epub 2020 Sep 8.

Department of Bioengineering, University of California, Los Angeles, CA 90095, USA.

Reactions performed in uniform microscale volumes have enabled numerous applications in the analysis of rare entities (e.g. cells and molecules). Here, highly monodisperse aqueous droplets are formed by simply mixing microscale multi-material particles, consisting of concentric hydrophobic outer and hydrophilic inner layers, with oil and water. The particles are manufactured in batch using a 3D printed device to co-flow four concentric streams of polymer precursors which are polymerized with UV light. The cross-sectional shapes of the particles are altered by microfluidic nozzle design in the 3D printed device. Once a particle encapsulates an aqueous volume, each "dropicle" provides uniform compartmentalization and customizable shape-coding for each sample volume to enable multiplexing of uniform reactions in a scalable manner. We implement an enzymatically-amplified immunoassay using the dropicle system, yielding a detection limit of <1 pM with a dynamic range of at least 3 orders of magnitude. Multiplexing using two types of shape-coded particles was demonstrated without cross talk, laying a foundation for democratized single-entity assays.
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http://dx.doi.org/10.1039/d0lc00698jDOI Listing
October 2020

Raman image-activated cell sorting.

Nat Commun 2020 07 10;11(1):3452. Epub 2020 Jul 10.

Department of Chemistry, The University of Tokyo, Tokyo, 113-0033, Japan.

The advent of image-activated cell sorting and imaging-based cell picking has advanced our knowledge and exploitation of biological systems in the last decade. Unfortunately, they generally rely on fluorescent labeling for cellular phenotyping, an indirect measure of the molecular landscape in the cell, which has critical limitations. Here we demonstrate Raman image-activated cell sorting by directly probing chemically specific intracellular molecular vibrations via ultrafast multicolor stimulated Raman scattering (SRS) microscopy for cellular phenotyping. Specifically, the technology enables real-time SRS-image-based sorting of single live cells with a throughput of up to ~100 events per second without the need for fluorescent labeling. To show the broad utility of the technology, we show its applicability to diverse cell types and sizes. The technology is highly versatile and holds promise for numerous applications that are previously difficult or undesirable with fluorescence-based technologies.
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http://dx.doi.org/10.1038/s41467-020-17285-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7351993PMC
July 2020

Microfluidic-Based Approaches in Targeted Cell/Particle Separation Based on Physical Properties: Fundamentals and Applications.

Small 2020 07 11;16(29):e2000171. Epub 2020 Jun 11.

Center for Minimally Invasive Therapeutics (C-MIT), University of California, Los Angeles, Los Angeles, CA, 90095, USA.

Cell separation is a key step in many biomedical research areas including biotechnology, cancer research, regenerative medicine, and drug discovery. While conventional cell sorting approaches have led to high-efficiency sorting by exploiting the cell's specific properties, microfluidics has shown great promise in cell separation by exploiting different physical principles and using different properties of the cells. In particular, label-free cell separation techniques are highly recommended to minimize cell damage and avoid costly and labor-intensive steps of labeling molecular signatures of cells. In general, microfluidic-based cell sorting approaches can separate cells using "intrinsic" (e.g., fluid dynamic forces) versus "extrinsic" external forces (e.g., magnetic, electric field, etc.) and by using different properties of cells including size, density, deformability, shape, as well as electrical, magnetic, and compressibility/acoustic properties to select target cells from a heterogeneous cell population. In this work, principles and applications of the most commonly used label-free microfluidic-based cell separation methods are described. In particular, applications of microfluidic methods for the separation of circulating tumor cells, blood cells, immune cells, stem cells, and other biological cells are summarized. Computational approaches complementing such microfluidic methods are also explained. Finally, challenges and perspectives to further develop microfluidic-based cell separation methods are discussed.
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http://dx.doi.org/10.1002/smll.202000171DOI Listing
July 2020

Intelligent image-activated cell sorting 2.0.

Lab Chip 2020 06;20(13):2263-2273

Department of Chemistry, The University of Tokyo, Tokyo 113-0033, Japan.

The advent of intelligent image-activated cell sorting (iIACS) has enabled high-throughput intelligent image-based sorting of single live cells from heterogeneous populations. iIACS is an on-chip microfluidic technology that builds on a seamless integration of a high-throughput fluorescence microscope, cell focuser, cell sorter, and deep neural network on a hybrid software-hardware data management architecture, thereby providing the combined merits of optical microscopy, fluorescence-activated cell sorting (FACS), and deep learning. Here we report an iIACS machine that far surpasses the state-of-the-art iIACS machine in system performance in order to expand the range of applications and discoveries enabled by the technology. Specifically, it provides a high throughput of ∼2000 events per second and a high sensitivity of ∼50 molecules of equivalent soluble fluorophores (MESFs), both of which are 20 times superior to those achieved in previous reports. This is made possible by employing (i) an image-sensor-based optomechanical flow imaging method known as virtual-freezing fluorescence imaging and (ii) a real-time intelligent image processor on an 8-PC server equipped with 8 multi-core CPUs and GPUs for intelligent decision-making, in order to significantly boost the imaging performance and computational power of the iIACS machine. We characterize the iIACS machine with fluorescent particles and various cell types and show that the performance of the iIACS machine is close to its achievable design specification. Equipped with the improved capabilities, this new generation of the iIACS technology holds promise for diverse applications in immunology, microbiology, stem cell biology, cancer biology, pathology, and synthetic biology.
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http://dx.doi.org/10.1039/d0lc00080aDOI Listing
June 2020

Deep learning-enabled point-of-care sensing using multiplexed paper-based sensors.

NPJ Digit Med 2020 7;3:66. Epub 2020 May 7.

1Department of Electrical and Computer Engineering, University of California, Los Angeles, CA USA.

We present a deep learning-based framework to design and quantify point-of-care sensors. As a use-case, we demonstrated a low-cost and rapid paper-based vertical flow assay (VFA) for high sensitivity C-Reactive Protein (hsCRP) testing, commonly used for assessing risk of cardio-vascular disease (CVD). A machine learning-based framework was developed to (1) determine an optimal configuration of immunoreaction spots and conditions, spatially-multiplexed on a sensing membrane, and (2) to accurately infer target analyte concentration. Using a custom-designed handheld VFA reader, a clinical study with 85 human samples showed a competitive coefficient-of-variation of 11.2% and linearity of  = 0.95 among blindly-tested VFAs in the hsCRP range (i.e., 0-10 mg/L). We also demonstrated a mitigation of the hook-effect due to the multiplexed immunoreactions on the sensing membrane. This paper-based computational VFA could expand access to CVD testing, and the presented framework can be broadly used to design cost-effective and mobile point-of-care sensors.
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http://dx.doi.org/10.1038/s41746-020-0274-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7206101PMC
May 2020

Peripheral Focused Ultrasound Neuromodulation (pFUS).

J Neurosci Methods 2020 07 6;341:108721. Epub 2020 May 6.

General Electric Global Research Center, Niskayuna, NY, USA. Electronic address:

Background: A fundamental limit to the study of the peripheral nervous system and its effect on organ function is the lack of tools to selectively target and stimulate specific neurons. Traditional implant and electrode-based systems remain too large and invasive for use at the organ or sub-organ level (without stimulating or effecting neighboring organs and tissues). Recent progress in optical and genetic tools (such as optogenetics) has provided a new level of molecular specificity and selectivity to the neurons that are stimulated by bioelectronic devices. However, the modified neurons that result from use of these tools (that can be selectively activated based on expression of light, heat, or stimuli sensitive ion channels) often still require stimulation by implantable devices and face difficult scientific, technical, and regulatory hurdles for clinical translation.

New Method: Herein, we present a new tool for selective activation of neuronal pathways using anatomical site-specific, peripheral focused ultrasound neuromodulation (pFUS).

Results: We utilize three experimental models to expand upon and further characterize pFUS beyond data outlined to our initial report (Cotero et al., 2019a), and further demonstrate its importance as a new investigative and translational tool. First, we utilized an interconnected microporous gel scaffold to culture isolated dorsal root ganglion (DRG) neurons in an interconnected, three-dimensional in vitro culture. (Griffin et al., 2015, Tay et al., 2018) Using this system, we directly applied ultrasound (US) stimuli and confirmed US activation of peripheral neurons at pressures consistent with recent in vivo observations. (Cotero et al., 2019a, Zachs, 2019, Gigliotti et al., 2013) Next, we tested the capability of pFUS to activate previously reported nerve pathways at multiple locations within the neural circuit, including primary sensory ganglia (i.e. inferior ganglion of the vagus nerve), peripheral ganglia (i.e. sacral ganglia), and within target end-organs. In addition, we compared selective activation of multiple anatomically overlapping neural pathways (i.e. activation of the cholinergic anti-inflammatory pathway (Tracey, 2009, Pavlov and Tracey, 2012) vs. metabolic sensory pathways (O'Hare and Zsombok, 2015, Roh et al., 2016, Pocai et al., 2005) after stimulation of each separate target site. Finally, we utilized an established model of metabolic dysfunction (the LPS-induced inflammation/hyperglycemia model) to demonstrate pFUS capability to stimulate and assess alternative therapeutic stimulation sites (i.e. liver, pancreas, and intestines) in a simple and clinically relevant manner. This is demonstrated by ultrasound induced attenuation of LPS-induced hyperglycemia by stimulation at all three anatomical targets, and mapping of the effect to a specific molecular product of excitable cell types within each stimulus site.

Comparison With Existing Methods: The ease-of-use and non-invasive nature of pFUS provides a solution to many of the challenges facing traditional toolsets, such as implantable electrodes and genetic/optogenetic nerve stimulation strategies.

Conclusions: The pFUS tool described herein provides a fundamental technology for the future study and manipulation of the peripheral nervous and neuroendocrine systems.
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http://dx.doi.org/10.1016/j.jneumeth.2020.108721DOI Listing
July 2020

Spectro-temporal encoded multiphoton microscopy and fluorescence lifetime imaging at kilohertz frame-rates.

Nat Commun 2020 04 28;11(1):2062. Epub 2020 Apr 28.

Department of Electrical Engineering and Computational Science, University of California, Los Angeles (UCLA), Los Angeles, CA-90095, USA.

Two-Photon Microscopy has become an invaluable tool for biological and medical research, providing high sensitivity, molecular specificity, inherent three-dimensional sub-cellular resolution and deep tissue penetration. In terms of imaging speeds, however, mechanical scanners still limit the acquisition rates to typically 10-100 frames per second. Here we present a high-speed non-linear microscope achieving kilohertz frame rates by employing pulse-modulated, rapidly wavelength-swept lasers and inertia-free beam steering through angular dispersion. In combination with a high bandwidth, single-photon sensitive detector, this enables recording of fluorescent lifetimes at speeds of 88 million pixels per second. We show high resolution, multi-modal - two-photon fluorescence and fluorescence lifetime (FLIM) - microscopy and imaging flow cytometry with a digitally reconfigurable laser, imaging system and data acquisition system. These high speeds should enable high-speed and high-throughput image-assisted cell sorting.
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http://dx.doi.org/10.1038/s41467-020-15618-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7188897PMC
April 2020

A comparison of microfluidic methods for high-throughput cell deformability measurements.

Nat Methods 2020 06 27;17(6):587-593. Epub 2020 Apr 27.

Biotechnology Center, Center for Molecular and Cellular Bioengineering, Technische Universität Dresden, Dresden, Germany.

The mechanical phenotype of a cell is an inherent biophysical marker of its state and function, with many applications in basic and applied biological research. Microfluidics-based methods have enabled single-cell mechanophenotyping at throughputs comparable to those of flow cytometry. Here, we present a standardized cross-laboratory study comparing three microfluidics-based approaches for measuring cell mechanical phenotype: constriction-based deformability cytometry (cDC), shear flow deformability cytometry (sDC) and extensional flow deformability cytometry (xDC). All three methods detect cell deformability changes induced by exposure to altered osmolarity. However, a dose-dependent deformability increase upon latrunculin B-induced actin disassembly was detected only with cDC and sDC, which suggests that when exposing cells to the higher strain rate imposed by xDC, cellular components other than the actin cytoskeleton dominate the response. The direct comparison presented here furthers our understanding of the applicability of the different deformability cytometry methods and provides context for the interpretation of deformability measurements performed using different platforms.
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http://dx.doi.org/10.1038/s41592-020-0818-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7275893PMC
June 2020

Hybrid Integrated Photomedical Devices for Wearable Vital Sign Tracking.

ACS Sens 2020 06 13;5(6):1582-1588. Epub 2020 Apr 13.

Department of Materials Science and Engineering, University of California, Los Angeles, Los Angeles, California 90095, United States.

In light of the importance of and challenges inherent in realizing a wearable healthcare platform for simultaneously recognizing, preventing, and treating diseases while tracking vital signs, the development of simple and customized functional devices has been required. Here, we suggest a new approach for making a stretchable light waveguide which can be combined with integrated functional devices, such as organic photodetectors (PDs) and nanowire-based heaters, for multifunctional healthcare monitoring. Controlling the reflection condition of the medium gave a solid design rule for strong light emission in our stretchable waveguides. Based on this rule, the stretchable light waveguide (up to 50% strain) made of polydimethylsiloxane was successfully demonstrated with strong emissions. We also incorporated highly sensitive organic PDs and silver nanowire-based heaters with the stretchable waveguide for the detection of vital signs, including the heart rate, deep breathing, coughs, and blood oxygen saturation. Through these multifunctional performances, we have successfully demonstrated that our stretchable light waveguide has a strong potential for multifunctional healthcare monitoring.
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http://dx.doi.org/10.1021/acssensors.9b02529DOI Listing
June 2020

Fractal LAMP: Label-Free Analysis of Fractal Precipitate for Digital Loop-Mediated Isothermal Nucleic Acid Amplification.

ACS Sens 2020 02 21;5(2):385-394. Epub 2020 Jan 21.

Department of Bioengineering , University of California , Los Angeles , California 90095 , United States.

Nucleic acid amplification assays including loop-mediated isothermal amplification (LAMP) are routinely used in diagnosing diseases and monitoring water and food quality. The results of amplification in these assays are commonly measured with an analog fluorescence readout, which requires specialized optical equipment and can lack quantitative precision. Digital analysis of amplification in small fluid compartments based on exceeding a threshold fluorescence level can enhance the quantitative precision of nucleic acid assays (i.e., digital nucleic acid amplification assays), but still requires specialized optical systems for fluorescence readout and the inclusion of a fluorescent dye. Here, we report Fractal LAMP, an automated method to detect amplified DNA in subnanoliter scale droplets following LAMP in a label-free manner. Our computer vision algorithm achieves high accuracy detecting DNA amplification in droplets by identifying LAMP byproducts that form fractal structures observable in brightfield microscopy. The capabilities of Fractal LAMP are further realized by developing a Bayesian model to estimate DNA concentrations for unknown samples and a bootstrapping method to estimate the number of droplets required to achieve target limits of detection. This digital, label-free assay has the potential to lower reagent and reader cost for nucleic acid measurement while maintaining high quantitative accuracy over 3 orders of magnitude of concentration.
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http://dx.doi.org/10.1021/acssensors.9b01974DOI Listing
February 2020

Effects of Flow-Induced Microfluidic Chip Wall Deformation on Imaging Flow Cytometry.

Cytometry A 2020 09 19;97(9):909-920. Epub 2019 Dec 19.

Center for Biosystems Dynamics Research (BDR), RIKEN, 1-3 Yamadaoka, Suita, Osaka, 565-0871, Japan.

Imaging flow cytometry is a powerful tool by virtue of its capability for high-throughput cell analysis. The advent of high-speed optical imaging methods on a microfluidic platform has significantly improved cell throughput and brought many degrees of freedom to instrumentation and applications over the last decade, but it also poses a predicament on microfluidic chips. Specifically, as the throughput increases, the flow speed also increases (currently reaching 10 m/s): consequently, the increased hydrodynamic pressure on the microfluidic chip deforms the wall of the microchannel and produces detrimental effects lead to defocused and blur image. Here, we present a comprehensive study of the effects of flow-induced microfluidic chip wall deformation on imaging flow cytometry. We fabricated three types of microfluidic chips with the same geometry and different degrees of stiffness made of polydimethylsiloxane (PDMS) and glass to investigate material influence on image quality. First, we found the maximum deformation of a PDMS microchannel was >60 μm at a pressure of 0.6 MPa, while no appreciable deformation was identified in a glass microchannel at the same pressure. Second, we found the deviation of lag time that indicating velocity difference of migrating microbeads due to the deformation of the microchannel was 29.3 ms in a PDMS microchannel and 14.9 ms in a glass microchannel. Third, the glass microchannel focused cells into a slightly narrower stream in the X-Y plane and a significantly narrower stream in the Z-axis direction (focusing percentages were increased 30%, 32%, and 5.7% in the glass channel at flow velocities of 0.5, 1.5, and 3 m/s, respectively), and the glass microchannel showed stabler equilibrium positions of focused cells regardless of flow velocity. Finally, we achieved the world's fastest imaging flow cytometry by combining a glass microfluidic device with an optofluidic time-stretch microscopy imaging technique at a flow velocity of 25 m/s. © 2019 International Society for Advancement of Cytometry.
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http://dx.doi.org/10.1002/cyto.a.23944DOI Listing
September 2020

Point-of-Care Serodiagnostic Test for Early-Stage Lyme Disease Using a Multiplexed Paper-Based Immunoassay and Machine Learning.

ACS Nano 2020 01 18;14(1):229-240. Epub 2019 Dec 18.

Department of Electrical & Computer Engineering , University of California , Los Angeles , California 90025 , United States.

Caused by the tick-borne spirochete , Lyme disease (LD) is the most common vector-borne infectious disease in North America and Europe. Though timely diagnosis and treatment are effective in preventing disease progression, current tests are insensitive in early stage LD, with a sensitivity of <50%. Additionally, the serological testing currently recommended by the U.S. Center for Disease Control has high costs (>$400/test) and extended sample-to-answer timelines (>24 h). To address these challenges, we created a cost-effective and rapid point-of-care (POC) test for early-stage LD that assays for antibodies specific to seven antigens and a synthetic peptide in a paper-based multiplexed vertical flow assay (xVFA). We trained a deep-learning-based diagnostic algorithm to select an optimal subset of antigen/peptide targets and then blindly tested our xVFA using human samples ( = 42, = 54), achieving an area-under-the-curve (AUC), sensitivity, and specificity of 0.950, 90.5%, and 87.0%, respectively, outperforming previous LD POC tests. With batch-specific standardization and threshold tuning, the specificity of our blind-testing performance improved to 96.3%, with an AUC and sensitivity of 0.963 and 85.7%, respectively.
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http://dx.doi.org/10.1021/acsnano.9b08151DOI Listing
January 2020

Natural Perspiration Sampling and in Situ Electrochemical Analysis with Hydrogel Micropatches for User-Identifiable and Wireless Chemo/Biosensing.

ACS Sens 2020 01 1;5(1):93-102. Epub 2019 Dec 1.

The Stanford Cystic Fibrosis Center, Center for Excellence in Pulmonary Biology , Stanford School of Medicine , Palo Alto , California 94305 , United States.

Recent advances in microelectronics, microfluidics, and electrochemical sensing platforms have enabled the development of an emerging class of fully integrated personal health monitoring devices that exploit sweat to noninvasively access biomarker information. Despite such advances, effective sweat sampling remains a significant challenge for reliable biomarker analysis, with many existing methods requiring active stimulation (e.g., iontophoresis, exercise, heat). Natural perspiration offers a suitable alternative as sweat can be collected with minimal effort on the part of the user. To leverage this phenomenon, we devised a thin hydrogel micropatch (THMP), which simultaneously serves as an interface for sweat sampling and a medium for electrochemical sensing. To characterize the performance of the THMP, caffeine and lactate were selected as two representative target molecules. We demonstrated the suitability of the sampling method to track metabolic patterns, as well as to render sample-to-answer biomarker data for personal monitoring (through coupling with an electrochemical sensing system). To inform its potential application, this biomarker sampling and sensing system is incorporated within a distributed terminal-based sensing network, which uniquely capitalizes on the fingertip as a site for simultaneous biomarker data sampling and user identification.
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http://dx.doi.org/10.1021/acssensors.9b01727DOI Listing
January 2020

Computational cytometer based on magnetically modulated coherent imaging and deep learning.

Light Sci Appl 2019 2;8:91. Epub 2019 Oct 2.

1Electrical and Computer Engineering Department, University of California, Los Angeles, CA 90095 USA.

Detecting rare cells within blood has numerous applications in disease diagnostics. Existing rare cell detection techniques are typically hindered by their high cost and low throughput. Here, we present a computational cytometer based on magnetically modulated lensless speckle imaging, which introduces oscillatory motion to the magnetic-bead-conjugated rare cells of interest through a periodic magnetic force and uses lensless time-resolved holographic speckle imaging to rapidly detect the target cells in three dimensions (3D). In addition to using cell-specific antibodies to magnetically label target cells, detection specificity is further enhanced through a deep-learning-based classifier that is based on a densely connected pseudo-3D convolutional neural network (P3D CNN), which automatically detects rare cells of interest based on their spatio-temporal features under a controlled magnetic force. To demonstrate the performance of this technique, we built a high-throughput, compact and cost-effective prototype for detecting MCF7 cancer cells spiked in whole blood samples. Through serial dilution experiments, we quantified the limit of detection (LoD) as 10 cells per millilitre of whole blood, which could be further improved through multiplexing parallel imaging channels within the same instrument. This compact, cost-effective and high-throughput computational cytometer can potentially be used for rare cell detection and quantification in bodily fluids for a variety of biomedical applications.
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http://dx.doi.org/10.1038/s41377-019-0203-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6804677PMC
October 2019