Publications by authors named "Mingdong Dong"

201 Publications

Multiple system atrophy-associated oligodendroglial protein p25α stimulates formation of novel α-synuclein strain with enhanced neurodegenerative potential.

Acta Neuropathol 2021 May 12. Epub 2021 May 12.

DANDRITE, Danish Research Institute of Translational Neuroscience & Department of Biomedicine, Aarhus University, 8000, Aarhus C, Denmark.

Pathology consisting of intracellular aggregates of alpha-Synuclein (α-Syn) spread through the nervous system in a variety of neurodegenerative disorders including Parkinson's disease, dementia with Lewy bodies, and multiple system atrophy. The discovery of structurally distinct α-Syn polymorphs, so-called strains, supports a hypothesis where strain-specific structures are templated into aggregates formed by native α-Syn. These distinct strains are hypothesised to dictate the spreading of pathology in the tissue and the cellular impact of the aggregates, thereby contributing to the variety of clinical phenotypes. Here, we present evidence of a novel α-Syn strain induced by the multiple system atrophy-associated oligodendroglial protein p25α. Using an array of biophysical, biochemical, cellular, and in vivo analyses, we demonstrate that compared to α-Syn alone, a substoichiometric concentration of p25α redirects α-Syn aggregation into a unique α-Syn/p25α strain with a different structure and enhanced in vivo prodegenerative properties. The α-Syn/p25α strain induced larger inclusions in human dopaminergic neurons. In vivo, intramuscular injection of preformed fibrils (PFF) of the α-Syn/p25α strain compared to α-Syn PFF resulted in a shortened life span and a distinct anatomical distribution of inclusion pathology in the brain of a human A53T transgenic (line M83) mouse. Investigation of α-Syn aggregates in brain stem extracts of end-stage mice demonstrated that the more aggressive phenotype of the α-Syn/p25α strain was associated with an increased load of α-Syn aggregates based on a Förster resonance energy transfer immunoassay and a reduced α-Syn aggregate seeding activity based on a protein misfolding cyclic amplification assay. When injected unilaterally into the striata of wild-type mice, the α-Syn/p25α strain resulted in a more-pronounced motoric phenotype than α-Syn PFF and exhibited a "tropism" for nigro-striatal neurons compared to α-Syn PFF. Overall, our data support a hypothesis whereby oligodendroglial p25α is responsible for generating a highly prodegenerative α-Syn strain in multiple system atrophy.
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http://dx.doi.org/10.1007/s00401-021-02316-0DOI Listing
May 2021

Frequency Shift Surface-Enhanced Raman Spectroscopy Sensing: An Ultrasensitive Multiplex Assay for Biomarkers in Human Health.

ACS Sens 2021 May 3. Epub 2021 May 3.

CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety, Institute of High Energy Physics, the Chinese Academy of Sciences, Beijing 100049, China.

The sensitive and selective detection of biomarkers for human health remains one of the grand challenges of the analytical sciences. Compared to established methods (colorimetric, (chemi) luminescent), surface-enhanced Raman spectroscopy (SERS) is an emerging alternative with enormous potential for ultrasensitive biological detection. Indeed even attomolar (10 M) detection limits are possible for SERS due to an orders-of-magnitude boosting of Raman signals at the surface of metallic nanostructures by surface plasmons. However, challenges remain for SERS assays of large biomolecules, as the largest enhancements require the biomarker to enter a "hot spot" nanogap between metal nanostructures. The frequency-shift SERS method has gained popularity in recent years as an alternative assay that overcomes this drawback. It measures frequency shifts in intense SERS peaks of a Raman reporter during binding events on biomolecules (protein coupling, DNA hybridization, etc.) driven by mechanical transduction, charge transfer, or local electric field effects. As such, it retains the excellent multiplexing capability of SERS, with multiple analytes being identifiable by a spectral fingerprint in a single read-out. Meanwhile, like refractive index surface plasmon resonance methods, frequency-shift SERS measures the shift of an intense signal rather than resolving a peak above noise, easing spectroscopic resolution requirements. SERS frequency-shift assays have proved particularly suitable for sensing large, highly charged biomolecules that alter hydrogen-bonding networks upon specific binding. Herein we discuss the frequency-shift SERS method and promising applications in (multiplex) biomarker sensing as well as extensions to ion and gas sensing and much more.
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http://dx.doi.org/10.1021/acssensors.1c00393DOI Listing
May 2021

Studies on the electrostatic effects of stretched PVDF films and nanofibers.

Nanoscale Res Lett 2021 May 3;16(1):79. Epub 2021 May 3.

Sino-Danish Center for Education and Research (SDC), Interdisciplinary Nanoscience Center (iNANO), Aarhus University, DK-8000, Aarhus C, Denmark.

The electroactive β-phase in Poly (vinylidene fluoride, PVDF) is the most desirable conformation due to its highest pyro- and piezoelectric properties, which make it feasible to be used as flexible sensors, wearable electronics, and energy harvesters etc. In this study, we successfully developed a method to obtain high-content β-phase PVDF films and nanofiber meshes by mechanical stretching and electric spinning. The phase transition process and pyro- and piezoelectric effects of stretched films and nanofiber meshes were characterized by monitoring the polarized light microscopy (PLM) images, outputting currents and open-circuit voltages respectively, which were proved to be closely related to stretching ratio (λ) and concentrations. This study could expand a new route for the easy fabrication and wide application of PVDF films or fibers in wearable electronics, sensors, and energy harvesting devices.
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http://dx.doi.org/10.1186/s11671-021-03536-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8093351PMC
May 2021

Editorial: Material Surfaces and Interfaces at the Nanoscale: From Theory to Application.

Front Chem 2021 12;9:656661. Epub 2021 Mar 12.

Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Aarhus, Denmark.

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http://dx.doi.org/10.3389/fchem.2021.656661DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7994527PMC
March 2021

Silk fibroin H-fibroin/poly(ε-caprolactone) core-shell nanofibers with enhanced mechanical property and long-term drug release.

J Colloid Interface Sci 2021 Jul 9;593:142-151. Epub 2021 Mar 9.

School of Materials Science and Engineering and Institute for Advanced Materials, Jiangsu University, Zhenjiang 212013, China. Electronic address:

The scaffold materials with good mechanical and structural properties, controlled drug release performance, biocompatibility and biodegradability are important tenet in tissue engineering. In this work, the functional core-shell nanofibers with poly(ε-caprolactone) (PCL) as shell and silk fibroin heavy chain (H-fibroin) as core were constructed by emulsion electrospinning. The transmission electron microscopy confirmed that the nanofiber with core-shell structure were successfully prepared. The constructed nanofiber materials were characterized by the several characterization methods. The results showed that ethanol treatment could induce the formation of β-sheet of H-fibroin in composite nanofibers, thus improving the mechanical properties of PCL/H-fibroin nanofiber scaffold. In addition, we evaluated the potential of PCL/H-fibroin nanofiber membrane as a biological scaffold. It was found that PCL/H-fibroin nanofiber scaffold was more conducive to cell adhesion and proliferation with the increment of H-fibroin. Finally, in vitro drug release presented that PCL/H-fibroin core-shell nanofibers could effectively reduce the prophase burst of drug molecules and show the sustained drug release. The PCL/H-fibroin nanofiber scaffolds constructed in this work have good mechanical properties, biocompatibility, and display good potential in biomedical applications, such as drug carriers, tissue engineering and wound dressings, etc.
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http://dx.doi.org/10.1016/j.jcis.2021.02.099DOI Listing
July 2021

Long-distance electron transfer in a filamentous Gram-positive bacterium.

Nat Commun 2021 03 17;12(1):1709. Epub 2021 Mar 17.

Interdisciplinary Nanoscience Center (iNANO), Sino-Danish Center for Education and Research (SDC), Aarhus University, Aarhus, Denmark.

Long-distance extracellular electron transfer has been observed in Gram-negative bacteria and plays roles in both natural and engineering processes. The electron transfer can be mediated by conductive protein appendages (in short unicellular bacteria such as Geobacter species) or by conductive cell envelopes (in filamentous multicellular cable bacteria). Here we show that Lysinibacillus varians GY32, a filamentous unicellular Gram-positive bacterium, is capable of bidirectional extracellular electron transfer. In microbial fuel cells, L. varians can form centimetre-range conductive cellular networks and, when grown on graphite electrodes, the cells can reach a remarkable length of 1.08 mm. Atomic force microscopy and microelectrode analyses suggest that the conductivity is linked to pili-like protein appendages. Our results show that long-distance electron transfer is not limited to Gram-negative bacteria.
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http://dx.doi.org/10.1038/s41467-021-21709-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7969598PMC
March 2021

Melt Electrospinning Writing of Magnetic Microrobots.

Adv Sci (Weinh) 2021 Feb 4;8(3):2003177. Epub 2021 Jan 4.

Interdisciplinary Nanoscience Center (iNANO) Sino-Danish Center for Education and Research (SDC) Aarhus University Aarhus C DK-8000 Denmark.

The magnetic microrobots actuated by an external magnetic field can access distant, enclosed, and small spaces under fuel-free conditions, which is apromising technology for manipulation and delivery under microenvironment; however, the complicated fabrication method limits their applications. Herein, three techniques including melt electrospinning writing (MEW), micromolding, and skiving process are combined to successfully mass-produce tadpole-like magnetic polycaprolactone/FeO (PCL/FeO) microrobot. Importantly, the tadpole-like microrobots under an external magnetic field can achieve two locomotions: rolling mode and propulsion mode. The rolling motion can approach the working destination quickly with a speed of ≈2 mm s. The propulsion motion (0-340 µm s) can handle a microcargo. Such a simple and cost-effective production method shows a great potential for scale-up fabrication of advanced shape-design, mass-production, and multifunctionality microrobot.
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http://dx.doi.org/10.1002/advs.202003177DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7856894PMC
February 2021

In Situ Resistive Switching Effect Scrutinization on Co-Designed Graphene Sensor.

Small 2021 Feb 1;17(8):e2007053. Epub 2021 Feb 1.

Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Aarhus C, Aarhus, DK, 8000, Denmark.

Resistive switching (RS), an electric property based on the forming and rupture of conductive filaments in metal-insulator-metal structures, has attracted intensive attention due to its potential application in next generation energy-efficient and area-efficient memory devices. In situ studies of the RS effect are urgently needed for its mechanism understanding and memristive performance improvement. Here investigations of both the RS effect as well as the gate tunable conductance quantization effect are realized by co-designing an Ag/SiO based memory structure on a graphene local sensor. This design enables self-monitoring of the working states of the memristor in real-time by virtue of the graphene sensor. These findings pave the way for further investigations of on-chip electronics and quantum physics.
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http://dx.doi.org/10.1002/smll.202007053DOI Listing
February 2021

Growing vertical aligned mesoporous silica thin film on nanoporous substrate for enhanced degradation, drug delivery and bioactivity.

Bioact Mater 2021 May 10;6(5):1452-1463. Epub 2020 Nov 10.

State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Diseases & Shaanxi Key Laboratory of Oral Diseases, Department of Prosthodontics, School of Stomatology, The Fourth Military Medical University, Xi'an, 710032, China.

Mesoporous silica thin film has been widely used in various fields, particularly the medical implant coating for drug delivery. However, some drawbacks remain with the films produced by traditional method (evaporation-induced self-assembly, EISA), such as the poor permeability caused by their horizontal aligned mesochannels. In this study, the vertical aligned mesoporous silica thin film (VMSTF) is uniformly grown alongside the walls of titania nanotubes array via a biphase stratification growth method, resulting in a hierarchical two-layered nanotubular structure. Due to the exposure of opened mesopores, VMSTF exhibits more appealing performances, including rapid degradation, efficient small-molecular drug (dexamethasone) loading and release, enhanced early adhesion and osteogenic differentiation of MC3T3-E1 cells. This is the first time successfully depositing VMSTF on nanoporous substrate and our findings suggest that the VMSTF may be a promising candidate for bone implant surface coating to obtain bioactive performances.
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http://dx.doi.org/10.1016/j.bioactmat.2020.10.026DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7670213PMC
May 2021

Pressure-driven switching of magnetism in layered CrCl.

Nanoscale 2020 Nov;12(45):22935-22944

Department of Physics and Shenzhen Engineering Research Center for Frontier Materials Synthesis at High Pressure, Southern University of Science and Technology, Shenzhen 518055, China.

Layered transition-metal compounds with controllable magnetic behaviors provide many fascinating opportunities for the fabrication of high-performance magneto-electric and spintronic devices. The tuning of their electronic and magnetic properties is usually limited to the change of layer thickness, electrostatic doping, and the control of electric and magnetic fields. However, pressure has been rarely exploited as a control parameter for tailoring their magneto-electric properties. Here, we report a unique pressure-driven isostructural phase transition in layered CrCl3 accompanied by a simultaneous switching of magnetism from a ferromagnetic to an antiferromagnetic ordering. Our experiments, in combination with ab initio calculations, demonstrate that such a magnetic transition hinders the bandgap collapse under pressure, leading to an anomalous semiconductor-to-semiconductor transition. Our findings not only reveal the potential applications of this material in electronic and spintronic devices but also establish the basis for exploring unusual phase transitions in layered transition-metal compounds.
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http://dx.doi.org/10.1039/d0nr04325gDOI Listing
November 2020

Flexible and Green Electronics Manufactured by Origami Folding of Nanosilicate-Reinforced Cellulose Paper.

ACS Appl Mater Interfaces 2020 Oct 9;12(42):48027-48039. Epub 2020 Oct 9.

Department of Health Technology, Institute of Biotherapeutic Engineering and Drug Targeting, Center for Intestinal Absorption and Transport of Biopharmaceuticals, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark.

Today's consumer electronics are made from nonrenewable and toxic components. They are also rigid, bulky, and manufactured in an energy-inefficient manner via CO-generating routes. Though petroleum-based polymers such as polyethylene terephthalate and polyethylene naphthalate can address the rigidity issue, they have a large carbon footprint and generate harmful waste. Scalable routes for manufacturing electronics that are both flexible and ecofriendly (Fleco) could address the challenges in the field. Ideally, such substrates must incorporate into electronics without compromising device performance. In this work, we demonstrate that a new type of wood-based [nanocellulose (NC)] material made via nanosilicate (NS) reinforcement can yield flexible electronics that can bend and roll without loss of electrical function. Specifically, the NSs interact electrostatically with NC to reinforce thermal and mechanical properties. For instance, films containing 34 wt % of NS displayed an increased young's modulus (1.5 times), thermal stability (290 → 310 °C), and a low coefficient of thermal expansion (40 ppm/K). These films can also easily be separated and renewed into new devices through simple and low-energy processes. Moreover, we used very cheap and environmentally friendly NC from American Value Added Pulping (AVAP) technology, American Process, and therefore, the manufacturing cost of our NS-reinforced NC paper is much cheaper ($0.016 per dm) than that of conventional NC-based substrates. Looking forward, the methodology highlighted herein is highly attractive as it can unlock the secrets of Fleco electronics and transform otherwise bulky, rigid, and "difficult-to-process" rigid circuits into more aesthetic and flexible ones while simultaneously bringing relief to an already-overburdened ecosystem.
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http://dx.doi.org/10.1021/acsami.0c15326DOI Listing
October 2020

Effect of cholesterol on the fluidity of supported lipid bilayers.

Colloids Surf B Biointerfaces 2020 Dec 6;196:111353. Epub 2020 Sep 6.

State Key Laboratory of Urban Water Resource, Environment School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin, 150001, China. Electronic address:

The lateral mobility serves as a key function of the cell membrane and can be regulated by the cholesterol. Here supported lipid bilayers were used to quantitatively analyse the influence of cholesterol on the fluidity of lipid bilayer in the environments with and without an electric field. We observed that with the increase of cholesterol proportion (0-30 mol%), the diffusion coefficient of DOPC lipid bilayer gradually decreased from 1.30 ± 0.15 μm s to 0.28 ± 0.13 μm s, where as that of DPPC lipid bilayer increased slightly from ∼0 to 0.45 ± 0.18 μm s. We then showed that cholesterol also regulated the movement of charged lipids in the bilayer in the electric field. The migration rate of charged lipids in the DOPC bilayers slowed down as the cholesterol increased. The clarification of the dose-effect relationship of cholesterol for the bidirectional regulating effect on the mobility of lipid bilayer will extend applications of supported lipid bilayers as the model of cell membrane.
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http://dx.doi.org/10.1016/j.colsurfb.2020.111353DOI Listing
December 2020

Structural conversion of human islet amyloid polypeptide aggregates under an electric field.

Chem Commun (Camb) 2020 Sep;56(77):11497-11500

Institute for Advanced Materials, Jiangsu University, China.

Electric fields (EFs) in biological systems are well known, and their presence implies the activity of protein ion channels and pumps in various cells. The aggregation of islet amyloid polypeptides (IAPP) was recently found in human brain tissue, and this was related to the electrical activity of neurons and caused neuronal loss. However, the association between amyloid formation and the electric field is still unknown. Herein a direct method to stimulate the formation of the hIAPP peptide under an EF is reported.
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http://dx.doi.org/10.1039/d0cc04466kDOI Listing
September 2020

An injectable high-conductive bimaterial scaffold for neural stimulation.

Colloids Surf B Biointerfaces 2020 Jun 22;195:111210. Epub 2020 Jun 22.

Department of Engineering and Interdisciplinary Nanoscience Center, Aarhus University, 8000 Aarhus C, Denmark. Electronic address:

Neurological recovery is difficult due to limited axonal regeneration and the limitations of autograft therapeutics in repairing peripheral nerve defects. Alternatively, the implantable nerve guidance conduit represents a promising approach for the nerve regeneration of especially large injury gaps. Herein, we presented an easily injectable and highly conductive, tissue engineering scaffold for supporting nerve cells growth and promoting neural differentiation. The ultra-flexible conductive scaffold was prepared by the combination of PCL-based micro-grid via melt electrowriting (MEW) with a nanolayer of gold via sputter coating, which shows good mechanical properties (including high flexibility and recoverability) and high conductivity. The conductive interface acts as a bridge for electrical signal transmission between nerve cells under electrical stimulation, which significantly enhances neural differentiation and improves the neurite outgrowth. Specifically, compared with the PCL group, the neurite length of the 50 Au-PCL and 80 Au-PCL groups increased by nearly 10 and 15 times respectively, after 10 days of culture without ES treatment. Furthermore, as the increase of Au coating thickness, the promotion of the ES effect was further improved. The 80 Au-PCL group showed the highest average neurite length and neurite number per cell compared with PCL (11 times), 20 Au-PCL (9 times), 50Au-PCL (3 times) after ES treatment for 5 days (one hour per day). Overall, our Au-PCL bimaterial scaffold is a promising nerve repair material because of its suitable injectability, high conductivity, biocompatibility, and powerful ability to promote neural stimulation.
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http://dx.doi.org/10.1016/j.colsurfb.2020.111210DOI Listing
June 2020

Coupling N and CO in HO to synthesize urea under ambient conditions.

Nat Chem 2020 08 15;12(8):717-724. Epub 2020 Jun 15.

State Key Laboratory of Chem/Bio-Sensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, P. R. China.

The use of nitrogen fertilizers has been estimated to have supported 27% of the world's population over the past century. Urea (CO(NH)) is conventionally synthesized through two consecutive industrial processes, N + H → NH followed by NH + CO → urea. Both reactions operate under harsh conditions and consume more than 2% of the world's energy. Urea synthesis consumes approximately 80% of the NH produced globally. Here we directly coupled N and CO in HO to produce urea under ambient conditions. The process was carried out using an electrocatalyst consisting of PdCu alloy nanoparticles on TiO nanosheets. This coupling reaction occurs through the formation of C-N bonds via the thermodynamically spontaneous reaction between *N=N* and CO. Products were identified and quantified using isotope labelling and the mechanism investigated using isotope-labelled operando synchrotron-radiation Fourier transform infrared spectroscopy. A high rate of urea formation of 3.36 mmol g h and corresponding Faradic efficiency of 8.92% were measured at -0.4 V versus reversible hydrogen electrode.
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http://dx.doi.org/10.1038/s41557-020-0481-9DOI Listing
August 2020

Facile fabrication of Mn-doped ZnO photocatalysts by electrospinning.

R Soc Open Sci 2020 Apr 22;7(4):191050. Epub 2020 Apr 22.

School of Environment and Civil Engineering, Dongguan University of Technology, Guangdong 523808, People's Republic of China.

In this study, a high-efficiency photocatalyst was synthesized by Mn-doped ZnO nanofibres (NFs) fabricated by facile electrospinning and a following annealing process, in which Mn successes incorporate to ZnO NFs lattice without changing any morphology and crystalline structure of ZnO. The photodegradation properties of ZnO loading with different concentrations of Mn (5, 10, 15 and 50 at%) were investigated. The 50% MnO-ZnO composite owns excellent active photocatalytic performance (quantum efficiency up to 7.57%) compared to pure ZnO (0.16%) under visible light and can be considered as an efficient visible light photocatalyst material. We systematically analysed its catalytic mechanism and found that the enhancement belongs to the Mn doping effect and the phase junction between MnO and ZnO. The dominant mechanism of Mn doping leads to the presence of impurity levels in the band gap of ZnO, narrowing the optical band gap of ZnO. In addition, doped Mn ions can be used as electron traps that inhibit the recombination process and promote electron-hole pair separation. In summary, this paper provides a convenient method for fabricating highly efficient visible light photocatalysts using controlled annealing.
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http://dx.doi.org/10.1098/rsos.191050DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7211861PMC
April 2020

3D anisotropic photocatalytic architectures as bioactive nerve guidance conduits for peripheral neural regeneration.

Biomaterials 2020 09 10;253:120108. Epub 2020 May 10.

Interdisciplinary Nanoscience Center, Aarhus University, DK-8000, Aarhus C, Denmark; Department of Engineering, Aarhus University, DK-8000, Aarhus C, Denmark. Electronic address:

Great research efforts have been invested in developing nerve guidance conduits (NGCs), which can direct axons advance and guide peripheral neural regeneration. Here, three different aspects of NGC design, namely anisotropy, photocatalytic stimulation and self-assembly at implantation site, were unitedly addressed. Firstly, melt electrowriting (MEW) was used to print anisotropic, microfibrous PCL architectures. Specifically, by tailoring the fiber spacing ratio between two arms of the grid patterns (1-1, 1-2, 1-3), preferential neurite extension of PC 12 cells along the long arm direction was achieved. Such anisotropic neurites guidance was further strengthened when the intersection angles were reduced from 90° to 30°. Secondly, functionalization of PCL micropatterns with graphene oxide and graphitic carbon nitride (g-CN), a visible-light photocatalyst, may enable optoelectronic conversion and wireless neural stimulation. As a result, photocatalytic stimulation further enhanced neurite extension length under visible light irradiation. Last but not the least, NGC were successfully obtained either by manually rolling or self-assembly using a thermo-responsive bi-layer system. Interestingly, the anisotropic micropattern design dictated the self-assembly process, and an underlying mechanism was proposed. With a synergy of three unique design parameters, the herein presented NGCs may possess great potential for repairing peripheral nerve injuries.
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http://dx.doi.org/10.1016/j.biomaterials.2020.120108DOI Listing
September 2020

Studying the Pyroelectric Effects of LiNbO Modified Composites.

Nanoscale Res Lett 2020 May 12;15(1):106. Epub 2020 May 12.

Sino-Danish Center for Education and Research (SDC), interdisciplinary Nanoscience Center (iNANO), Aarhus University, Dk-8000, Aarhus C, Denmark.

LiNbO (LN) crystal has been widely used as a pyroelectric material due to its spontaneous electric polarization, which could be recharged easily and can directly convert heat energy into electricity. LN crystal's heat-resistant, low-cost, and low dielectric loss properties make it possible for its applications in room-temperature pyroelectric devices and thermal sensors. However, LN crystal suffers from fragility, inflexibility, and other mechanical properties, which limit its suitability for many applications in various fields. In this study, the LN modified flexible pyroelectric films, composed of LN micro-particles, polypropylene (PP) matrix, and multiwalled carbon nanotubes (MWCNTs), are successfully fabricated. The pyroelectric effects of LN crystal and LN/PP/MWCNT composite films are characterized by monitoring the patterned self-assembly of nanoparticles and the output pyroelectric currents. The excellent pyroelectric properties of the composites have potential applications in energy harvesters or sensors.
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http://dx.doi.org/10.1186/s11671-020-03341-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7218041PMC
May 2020

In situ Surface Charge Density Visualization of Self-assembled DNA Nanostructures after Ion Exchange.

Chemphyschem 2020 07 8;21(13):1474-1482. Epub 2020 Jun 8.

Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Denmark.

The charge density of DNA is a key parameter in strand hybridization and for the interactions occurring between DNA and molecules in biological systems. Due to the intricate structure of DNA, visualization of the surface charge density of DNA nanostructures under physiological conditions was not previously possible. Here, we perform a simultaneous analysis of the topography and surface charge density of DNA nanostructures using atomic force microscopy and scanning ion conductance microscopy. The effect of in situ ion exchange using various alkali metal ions is tested with respect to the adsorption of DNA origami onto mica, and a quantitative study of surface charge density reveals ion exchange phenomena in mica as a key parameter in DNA adsorption. This is important for structure-function studies of DNA nanostructures. The research provides an efficient approach to study surface charge density of DNA origami nanostructures and other biological molecules at a single molecule level.
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http://dx.doi.org/10.1002/cphc.201901168DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7891384PMC
July 2020

Wafer-size growth of 2D layered SnSe films for UV-Visible-NIR photodetector arrays with high responsitivity.

Nanoscale 2020 Apr;12(13):7358-7365

School of Materials Science and Engineering, China University of Petroleum, Qingdao 266580, China.

Due to its excellent electrical and optical properties, tin selenide (SnSe), a typical candidate of two-dimensional (2D) semiconductors, has attracted great attention in the field of novel optoelectronics. However, the large-area growth of high-quality SnSe films still remains a great challenge, which limits their practical applications. Here, wafer-size SnSe ultrathin films with high uniformity and crystallization were deposited via a scalable magnetron sputtering method. The results showed that the SnSe photodetector was highly sensitive to a broad range of wavelengths in the UV-visible-NIR range, especially showing an extremely high responsivity of 277.3 A W-1 with the corresponding external quantum efficiency of 8.5 × 104% and detectivity of 7.6 × 1011 Jones. These figures of merits are among the best performances for the sputter-fabricated 2D photodetector devices. The photodetecting mechanisms based on a photogating effect induced by the trapping effect of localized defects are discussed in detail. The results indicate that the few-layered SnSe films obtained from sputtering growth have great potential in the design of high-performance photodetector arrays.
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http://dx.doi.org/10.1039/d0nr00319kDOI Listing
April 2020

Identification and Nanomechanical Characterization of the HIV Tat-Amyloid β Peptide Multifibrillar Structures.

Chemistry 2020 Aug 20;26(43):9449-9453. Epub 2020 Jul 20.

Key Laboratory of Colloid and Interface Chemistry of the Ministry of, Education, and School of Chemistry and Chemical Engineering, Shandong University, Jinan, 250100, P. R. China.

HIV transactivator of transcription (Tat) protein could interact with amyloid β (Aβ) peptide which cause the growth of Aβ plaques in the brain and result in Alzheimer's disease in HIV-infected patients. Herein, we employ high-resolution atomic force microscopy and quantitative nanomechanical mapping to investigate the effects of Tat protein in Aβ peptide aggregation. Our results demonstrate that the Tat protein could bind to the Aβ fibril surfaces and result in the formation of Tat-Aβ multifibrillar structures. The resultant Tat-Aβ multifibrillar aggregates represent an increase in stiffness compared with Aβ fibrils due to the increase in β-sheet formation. The identification and characterization of the Tat-Aβ intermediate aggregates is important to understanding the interactions between Tat protein and Aβ peptide, and the development of novel therapeutic strategy for Alzheimer's disease-like disorder in HIV infected individuals.
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http://dx.doi.org/10.1002/chem.201905715DOI Listing
August 2020

Reversing Interfacial Catalysis of Ambipolar WSe Single Crystal.

Adv Sci (Weinh) 2020 Feb 5;7(3):1901382. Epub 2019 Dec 5.

Interdisciplinary Nanoscience Center (iNANO) Aarhus University DK-8000 Aarhus C Denmark.

An improved understanding of the origin of the electrocatalytic activity is of importance to the rational design of highly efficient electrocatalysts for the hydrogen evolution reaction. Here, an ambipolar single-crystal tungsten diselenide (WSe) semiconductor is employed as a model system where the conductance and carrier of WSe can be individually tuned by external electric fields. The field-tuned electrochemical microcell is fabricated based on the single-crystal WSe and the catalytic activity of the WSe microcell is measured versus the external electric field. Results show that WSe with electrons serving as the dominant carrier yields much higher activity than WSe with holes serving as the dominant carrier even both systems exhibit similar conductance. The catalytic activity enhancement can be characterized by the Tafel slope decrease from 138 to 104 mV per decade, while the electron area concentration increases from 0.64 × 10 to 1.72 × 10 cm. To further understand the underlying mechanism, the Gibbs free energy and charge distribution for adsorbed hydrogen on WSe versus the area charge concentration is systematically computed, which is in line with experiments. This comprehensive study not only sheds light on the mechanism underlying the electrocatalysis processes, but also offers a strategy to achieve higher electrocatalytic activity.
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http://dx.doi.org/10.1002/advs.201901382DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7001631PMC
February 2020

An instant, biocompatible and biodegradable high-performance graphitic carbon nitride.

J Colloid Interface Sci 2020 Mar 9;563:336-346. Epub 2019 Dec 9.

Department of Environmental Science and Engineering, University of Shanghai for Science and Technology, 200093 Shanghai, PR China; Department of Materials Science & Engineering, University of Shanghai for Science and Technology, 200093 Shanghai, PR China. Electronic address:

Polymer graphitic carbon nitride (g-CN) materials have attracted growing interest owing to their impressive applicability in photocatalysis and optoelectronic devices. However, further applications of g-CN materials are greatly restricted by their chemical inertness and insolubility in most solvents. Regarding the rising prospect of g-CN nanosheets in the biomedicalfield, high solubility and biocompatibility are required for the further development of g-CN materials. In this study, a simple one-step thermal polymerization method was designed to prepare fast-soluble mesoporous g-CN nanosheets by using NHHSO as the critical adjuvant. The products, especially the optimal g-CN NSs-4, showed impressive solubility, biocompatibility and partial biodegradability. The enriched surface hydrophilic groups (-NH and -OH) may contribute to improving the solubility of g-CN nanosheets, while the partial biodegradability can be ascribed to the presence of the disulfide bond in the g-CN framework. In this system, the NHHSO adjuvant acted not only as O and S sources, but also as a bubbling agent that endows the g-CN a porous structure with greatly enlarged specific surface area and high separation efficiency of photogenerated electron-hole pairs. These integrative positive factors also greatly contributed to the photocatalytic activity of the g-CN nanosheets. This facile, economic and general fabrication strategy for mesoporous, fast-soluble and biocompatible g-CN with superior visible-light photocatalytic activity is promising in environmental, energy and biomedical fields.
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http://dx.doi.org/10.1016/j.jcis.2019.12.021DOI Listing
March 2020

Antifouling and pH-Responsive Poly(Carboxybetaine)-Based Nanoparticles for Tumor Cell Targeting.

Front Chem 2019 22;7:770. Epub 2019 Nov 22.

Key Laboratory of Colloid and Interface Chemistry of the Ministry of Education, School of Chemistry and Chemical Engineering, Shandong University, Jinan, China.

Nanocarriers with responsibility and surface functionality of targeting molecules have been widely used to improve therapeutic efficiency. Hence, we report the assembly of pH-responsive and targeted polymer nanoparticles (NPs) composed of poly(2-(diisopropylamino)ethyl methacrylate) (PDPA) as the core and poly(carboxybetaine methacrylate) (PCBMA) as the shell, functionalized with cyclic peptides containing Arginine-Glycine-Aspartic acid--Phenylalanine-Lysine (RGD). The resulting polymer NPs (PDPA@PCBMA-RGD NPs) can maintain the pH-responsivity of PDPA (pKa ~6.5) and low-fouling property of PCBMA that significantly resist non-specific interactions with RAW 264.7 and HeLa cells. Meanwhile, PDPA@PCBMA-RGD NPs could specifically target αβ integrin-expressed human glioblastoma (U87) cells. The pH-responsiveness and low-fouling properties of PDPA@PCBMA NPs are comparable to PDPA@poly(ethylene glycol) (PDPA@PEG) NPs, which indicates that PCBMA is an alternative to PEG for low-fouling coatings. The advantage of PDPA@PCBMA NPs lies in the presence of carboxyl groups on their surfaces for further modification (e.g., RGD functionalization for cell targeting). The reported polymer NPs represent a new carrier that have the potential for targeted therapeutic delivery.
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http://dx.doi.org/10.3389/fchem.2019.00770DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6883901PMC
November 2019

Multipathway Antibacterial Mechanism of a Nanoparticle-Supported Artemisinin Promoted by Nitrogen Plasma Treatment.

ACS Appl Mater Interfaces 2019 Dec 4;11(50):47299-47310. Epub 2019 Dec 4.

Interdisciplinary Nanoscience Center, Sino-Danish Center for Education and Research , Aarhus University , Aarhus 8000 , Denmark.

Artemisinin has excellent antimalarial, antiparasitic, and antibacterial activities; however, the poor water solubility of artemisinin crystal limits their application in antibiosis. Herein, artemisinin crystal was first composited with silica nanoparticles (SNPs) to form an artemisinin@silica nanoparticle (A@SNP). After treating with nitrogen plasma, the aqueous solubility of plasma-treated A@SNP (A@SNP-p) approaches 42.26%, which is possibly attributed to the exposure of hydrophilic groups such as -OH groups on the SNPs during the plasma process. Compared with the pristine A@SNP, the antibacterial activity of A@SNP-p against both Gram-positive and Gram-negative strains is further enhanced, and its bactericidal rate against both strains exceeded 6 log CFU/mL (>99.9999%), which is contributed by the increased water solubility of the A@SNP-p. A possible multipathway antibacterial mechanism of A@SNP was proposed and preliminarily proved by the changes of intracellular materials of bacteria and the inhibition of bacterial metabolism processes, including the HMP pathway in Gram-negative strain and EMP pathway in Gram-positive strain, after treating with A@SNP-p. These findings from the present work will provide a new view for fabricating artemisinin-based materials as antibiotics.
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http://dx.doi.org/10.1021/acsami.9b15124DOI Listing
December 2019

Progress of electrospray and electrospinning in energy applications.

Nanotechnology 2020 Mar 30;31(13):132001. Epub 2019 Oct 30.

School of Energy and Power Engineering, Jiangsu University, Zhenjiang 212013, People's Republic of China.

In the promotion of energy strategies to address the global energy crisis, nanotechnology has been successfully used to generate novel energy materials with excellent characteristics, such as high specific surface area, good flexibility and large porosity. Among the various methods for fabricating nanoscale materials, electrospray and electrospinning technologies have unlocked low-cost, facile and industrial routes to nanotechnology over the past ten years. This review highlights research into the key parts and primary theory of these techniques and their application in preparing energy-related materials and devices: especially fuel cells, solar cells, lithium ion batteries, supercapacitors as well as hydrogen storage systems. The challenges and future prospects of the manufacturing technologies are also covered in this paper.
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http://dx.doi.org/10.1088/1361-6528/ab52bbDOI Listing
March 2020

A Magnetic Dynamic Microbiointerface with Biofeedback Mechanism for Cancer Cell Capture and Release.

ACS Appl Mater Interfaces 2019 Nov 24;11(44):41019-41029. Epub 2019 Oct 24.

Interdisciplinary Nanoscience Center (iNANO) , Aarhus University , DK-8000 Aarhus , Denmark.

Dynamic biointerfaces with reversible surface bioactivities enable dynamic modulation of cell-material interactions, thus attracting great attention in biomedical science. Herein, we demonstrated a paradigm shift of dynamic biointerfaces from macroscopical substrates to micron-sized particles by reversible engineering of a phenylboronic acid (PBA)-functionalized magnetic microbead with mussel-inspired cancer cell-targeting peptide. Due to reversible catechol-boronate interactions between the peptides and microbeads, the micron-sized dynamic biointerface exhibited sugar-responsive cancer-targeting activity, showing the potential as a microplatform for magnetic and noninvasive isolation of cancer cells through natural biofeedback mechanism (e.g., human glycemic volatility). Our results demonstrated that the dynamic magnetic platform was capable of selective cancer cell capture (∼85%) and sugar-triggered release of them (>93%) in cell culture medium with high efficiency. More importantly, by using this platform, a decent number of target cells (∼23 on average) could be magnetically isolated and identified from artificial CTC blood samples (1 mL) spiked with 100 cancer cells. In view of the biomimetic nature, high capture efficiency, excellent selectivity, and superiority in cell separation and purification processes, the dynamic magnetic microplatform reported here would be a promising and general tool for rare cell detection and separation and cell-based disease diagnosis.
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http://dx.doi.org/10.1021/acsami.9b13140DOI Listing
November 2019

Stimulating antibacterial activities of graphitic carbon nitride nanosheets with plasma treatment.

Nanoscale 2019 Oct;11(39):18416-18425

School of Food & Biological Engineering, Jiangsu University, Zhenjiang 212013, China.

As a widely studied photoactive antibacterial nanomaterial, the intrinsic antibacterial traits of graphitic carbon nitride (g-C3N4) as a two-dimensional nanomaterial have not been reported so far. Herein, nitrogen-plasma-treated g-C3N4 (N-g-C3N4) nanosheets and their influence on bactericidal characteristics are investigated. Bactericidal rates of more than 99% have been successfully achieved for 8 kinds of foodborne pathogenic bacteria by N-g-C3N4 with 8 h incubation in the dark. The achieved rates are percentage wise 10 times higher than those for pristine g-C3N4. Cell rupture caused by direct mechanical contact between g-C3N4 nanosheets and cell membranes is observed. X-ray photoelectron spectroscopy revealed a substantial loss of surface defects and nitrogen vacancies in N-g-C3N4. Molecular dynamics simulations further indicated that the largely sealed defects of N-g-C3N4 enhanced the electrostatic attraction between inherent pores and lipid heads; thus, further insertion of N-g-C3N4 was promoted, resulting in enhanced antibacterial activity. This study establishes novel fabrication and application strategies for carbon based antibacterial nanomaterials.
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http://dx.doi.org/10.1039/c9nr03797gDOI Listing
October 2019

Waterproof molecular monolayers stabilize 2D materials.

Proc Natl Acad Sci U S A 2019 10 1;116(42):20844-20849. Epub 2019 Oct 1.

Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139;

Two-dimensional van der Waals materials have rich and unique functional properties, but many are susceptible to corrosion under ambient conditions. Here we show that linear alkylamines -C HNH, with = 4 through 11, are highly effective in protecting the optoelectronic properties of these materials, such as black phosphorus (BP) and transition-metal dichalcogenides (TMDs: WS, 1T'-MoTe, WTe, WSe, TaS, and NbSe). As a representative example, -hexylamine ( = 6) can be applied in the form of thin molecular monolayers on BP flakes with less than 2-nm thickness and can prolong BP's lifetime from a few hours to several weeks and even months in ambient environments. Characterizations combined with our theoretical analysis show that the thin monolayers selectively sift out water molecules, forming a drying layer to achieve the passivation of the protected 2D materials. The monolayer coating is also stable in air, H annealing, and organic solvents, but can be removed by certain organic acids.
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http://dx.doi.org/10.1073/pnas.1909500116DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6800348PMC
October 2019

Engineering a Genetically Encoded Magnetic Protein Crystal.

Nano Lett 2019 10 25;19(10):6955-6963. Epub 2019 Sep 25.

Department of Chemistry , Stanford University , Stanford , California 94305 , United States.

Magnetogenetics is a new field that leverages genetically encoded proteins and protein assemblies that are sensitive to magnetic fields to study and manipulate cell behavior. Theoretical studies show that many proposed magnetogenetic proteins do not contain enough iron to generate substantial magnetic forces. Here, we have engineered a genetically encoded ferritin-containing protein crystal that grows inside mammalian cells. Each of these crystals contains more than 10 million ferritin subunits and is capable of mineralizing substantial amounts of iron. When isolated from cells and loaded with iron , these crystals generate magnetic forces that are 9 orders of magnitude larger than the forces from the single ferritin cages used in previous studies. These protein crystals are attracted to an applied magnetic field and move toward magnets even when internalized into cells. While additional studies are needed to realize the full potential of magnetogenetics, these results demonstrate the feasibility of engineering protein assemblies for magnetic sensing.
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http://dx.doi.org/10.1021/acs.nanolett.9b02266DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7265822PMC
October 2019