Publications by authors named "Josué Juárez"

23 Publications

  • Page 1 of 1

Microfluidics-assisted conjugation of chitosan-coated polymeric nanoparticles with antibodies: Significance in drug release, uptake, and cytotoxicity in breast cancer cells.

J Colloid Interface Sci 2021 Jun 13;591:440-450. Epub 2021 Feb 13.

Laboratorio de Inmunología, Departamento de Fisiología, Centro Universitario de Ciencias de la Salud (CUCS), Universidad de Guadalajara, Guadalajara 44340, Mexico. Electronic address:

Nanoparticle-based drug delivery systems, in combination with high-affinity disease-specific targeting ligands, provide a sophisticated landscape in cancer theranostics. Due to their high diversity and specificity to target cells, antibodies are extensively used to provide bioactivity to a plethora of nanoparticulate systems. However, controlled and reproducible assembly of nanoparticles (NPs) with these targeting ligands remains a challenge. In this context, determinants such as ligand density and orientation, play a significant role in antibody bioactivity; nevertheless, these factors are complicated to control in traditional bulk labeling methods. Here, we propose a microfluidic-assisted methodology using a polydimethylsiloxane (PDMS) Y-shaped microreactor for the covalent conjugation of Trastuzumab (TZB), a recombinant antibody targeting HER2 (human epidermal growth factor receptor 2), to doxorubicin-loaded PLGA/Chitosan NPs (PLGA/DOX/Ch NPs) using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) and N-hydroxysulfosuccinimide (sNHS) mediated bioconjugation reactions. Our labeling approach led to smaller and less disperse nanoparticle-antibody conjugates providing differential performance when compared to bulk-labeled NPs in terms of drug release kinetics (fitted and analyzed with DDSolver), cell uptake/labeling, and cytotoxic activity on HER2 + breast cancer cells in vitro. By controlling NP-antibody interactions in a laminar regime, we managed to optimize NP labeling with antibodies resulting in ordered coronas with optimal orientation and density for bioactivity, providing a cheap and reproducible, one-step method for labeling NPs with globular targeting moieties.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jcis.2021.02.031DOI Listing
June 2021

Biodegradable photoresponsive nanoparticles for chemo-, photothermal- and photodynamic therapy of ovarian cancer.

Mater Sci Eng C Mater Biol Appl 2020 Nov 17;116:111196. Epub 2020 Jun 17.

Laboratorio de Inmunología, Departamento de Fisiología, Centro Universitario de Ciencias de la Salud (CUCS), Universidad de Guadalajara, Guadalajara 44340, Mexico. Electronic address:

Ovarian cancer (OC) is the deadliest gynecological cancer. Standard treatment of OC is based on cytoreductive surgery followed by chemotherapy with platinum drugs and taxanes; however, innate and acquired drug-resistance is frequently observed followed by a relapse after treatment, thus, more efficient therapeutic approaches are required. Combination therapies involving phototherapies and chemotherapy (the so-called chemophototherapy) may have enhanced efficacy against cancer, by attacking cancer cells through different mechanisms, including DNA-damage and thermally driven cell membrane and cytoskeleton damage. We have designed and synthesized poly(lactic-co-glycolic) nanoparticles (PLGA NPs) containing the chemo-drug carboplatin (CP), and the near infrared (NIR) photosensitizer indocyanine green (ICG). We have evaluated the drug release profile, the photodynamic ROS generation and photothermal capacities of the NPs. Also, the antitumoral efficiency of the NPs was evaluated using the SKOV-3 cell line as an in vitro OC model, observing an enhanced cytotoxic effect when irradiating cells with an 800 nm laser. Evidence here shown supports the potential application of the biodegradable photoresponsive NPs in the clinical stage due to the biocompatibility of the materials used, the spatiotemporal control of the therapy and, also, the less likely development of resistance against the combinatorial therapy.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.msec.2020.111196DOI Listing
November 2020

Improving Cell Penetration of Gold Nanorods by Using an Amphipathic Arginine Rich Peptide.

Int J Nanomedicine 2020 17;15:1837-1851. Epub 2020 Mar 17.

Departamento de Química Farmacológica y Toxicológica, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile.

Introduction: Gold nanorods are highly reactive, have a large surface-to-volume ratio, and can be functionalized with biomolecules. Gold nanorods can absorb infrared electromagnetic radiation, which is subsequently dispersed as local heat. Gold nanoparticles can be used as powerful tools for the diagnosis and therapy of different diseases. To improve the biological barrier permeation of nanoparticles with low cytotoxicity, in this study, we conjugated gold nanorods with cell-penetrating peptides (oligoarginines) and with the amphipathic peptide CLPFFD.

Methods: We studied the interaction of the functionalized gold nanorods with biological membrane models (liposomes) by dynamic light scattering, transmission electron microscopy and the Langmuir balance. Furthermore, we evaluated the effects on cell viability and permeability with an MTS assay and TEM.

Results And Discussion: The interaction study by DLS, the Langmuir balance and cryo-TEM support that GNR-ArgCLPFFD enhances the interactions between GNRs and biological membranes. In addition, cells treated with GNR-ArgCLPFFD internalized 80% more nanoparticles than cells treated with GNR alone and did not induce cell damage.

Conclusion: Our results indicate that incorporation of an amphipathic sequence into oligoarginines for the functionalization of gold nanorods enhances biological membrane nanoparticle interactions and nanoparticle cell permeability with respect to nanorods functionalized with oligoarginine. Overall, functionalized gold nanorods with amphipathic arginine rich peptides might be candidates for improving drug delivery by facilitating biological barrier permeation.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.2147/IJN.S237820DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7090188PMC
July 2020

Preparation and Characterization of Quercetin-Loaded Zein Nanoparticles by Electrospraying and Study of In Vitro Bioavailability.

J Food Sci 2019 Oct 25;84(10):2883-2897. Epub 2019 Sep 25.

Dept. of Research and Posgraduate in Food (DIPA), Univ. of Sonora. Blvd. Luis Encinas y Rosales, S/N, Colonia Centro, 83000, Hermosillo, Sonora, Mexico.

Quercetin is a hydrophobic flavonoid with high antioxidant activity. However, for biological applications, the bioavailability of quercetin is low due to physiological barriers. For this reason, an alternative is the protection of quercetin in matrices of biopolymers as zein. The objective of this work was to prepare and characterize quercetin-loaded zein nanoparticles by electrospraying and its study of in vitro bioavailability. The physicochemical parameters such as viscosity, density, and electrical conductivity of zein solutions showed a dependence of the ethanol concentration. In addition, rheological parameters demonstrated that solutions of zein in aqueous ethanol present Newtonian behavior, rebounding in the formation of nanoparticles by electrospraying, providing spherical, homogeneous, and compact morphologies, mainly at a concentration of 80% (v/v) of ethanol and of 5% (w/v) of zein. The size and shape of quercetin-loaded zein nanoparticles were studied by transmission electron microscopy (TEM), observing that it was entrapped, distributed throughout the nanoparticle of zein. Analysis by Fourier transform-infrared (FT-IR) of zein nanoparticles loaded with quercetin revealed interactions via hydrogen bonds. The efficacy of zein nanoparticles to entrap quercetin was particularly high for all quercetin concentration evaluated in this work (87.9 ± 1.5% to 93.0 ± 2.6%). The in vitro gastrointestinal release of trapped quercetin after 240 min was 79.1%, while that for free quercetin was 99.2%. The in vitro bioavailability was higher for trapped quercetin (5.9%) compared to free quercetin (1.9%), than of gastrointestinal digestion. It is concluded, that the electrospraying technique made possible the obtention of quercitin-loaded zein nanoparticles increasing their bioavailability. PRACTICAL APPLICATION: This type of nanosystems can be used in the food and pharmaceutical industry. Quercetin-loaded zein nanoparticles for its improvement compared to free quercetin can be used to decrease the prevalence of chronic degenerative diseases by increasing of the bioavailability of quercetin in the bloodstream. Other application can be as an antioxidant system in functional foods or oils to increase shelf life.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/1750-3841.14803DOI Listing
October 2019

Cisplatin-loaded PLGA nanoparticles for HER2 targeted ovarian cancer therapy.

Colloids Surf B Biointerfaces 2019 Jun 6;178:199-207. Epub 2019 Mar 6.

Laboratorio de Inmunología, Departamento de Fisiología, Centro Universitario de Ciencias de la Salud (CUCS), Universidad de Guadalajara, Guadalajara, 44340, Mexico.

The conventional treatment (cytoreduction combined with cisplatin/carboplatin and taxane drugs) of ovarian cancer has a high rate of failure and recurrence despite a favorable initial response. This lack of success is usually attributed to the development of multidrug resistance mechanisms by cancer cells and avoidance of the anti-growth effects of monoclonal targeted therapeutic antibodies. The disease, like other cancers, is characterized by the overexpression of molecular markers, including HER2 receptors. Preclinical and clinical studies with trastuzumab, a HER2-targeted therapeutic antibody, reveal a low improvement of the outcomes of HER2 positive ovarian cancer patients. Therefore, here, we propose a cisplatin-loaded, HER2 targeted poly(lactic-co-glycolic) nanoplatform, a system capable to escape the drug-efflux effect and to take advantage of the overexpressed HER2 receptors, using them as docks for targeted chemotherapy. The NP/trastuzumab ratio was determined after fluorescein labeling of antibodies and quantification of fluorescence in NPs. The system was also characterized in terms of size, zeta potential, drug release kinetics, cytotoxicity and cellular internalization in the epithelial ovarian cancer cell line SKOV-3, and compared with the HER2 negative breast cancer cell line HCC70. Our results show an increased cytotoxicity of NPs as compared to free cisplatin, and moreover, an enhanced internalization and cytotoxicity due to the bionfunctionalization of NPs with the monoclonal antibody.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.colsurfb.2019.03.011DOI Listing
June 2019

Gallic Acid-Loaded Zein Nanoparticles by Electrospraying Process.

J Food Sci 2019 Apr 25;84(4):818-831. Epub 2019 Feb 25.

Dept. of Research and Postgraduate in Food (DIPA), Univ. of Sonora, Blvd. Luis Encinas y Rosales, S/N, Colonia Centro, 83000, Hermosillo, Sonora, Mexico.

Currently, electrospraying is a novel process for obtaining the nanoparticles from biopolymers. Zein nanoparticles have been obtained by this method and used to protect both hydrophilic and hydrophobic antioxidant molecules from environmental factors. The objective of this work was to prepare and characterize gallic acid-loaded zein nanoparticles obtained by the electrospraying process to provide protection to gallic acid from environmental factors. Thus, it was related to the concentration of gallic acid in physicochemical and rheological properties of the electrosprayed solution, and also to equipment parameters, such as voltage, flow rate, and distance of the collector in morphology, and particle size. The physicochemical properties showed a relationship in the formation of a Taylor cone, in which at a low concentration of gallic acid (1% w/v), low viscosity (0.00464 ± 0.00001 Pa·s), and density (0.886 ± 0.00002 g/cm ), as well as high electrical conductivity (369 ± 4.3 µs/cm), forms a stable cone-jet mode. The rheological properties and the Power Law model of the gallic acid-zein electrosprayed solution demonstrated Newtonian behavior (n = 1). The morphology and size of the particle were dependent on the concentration of gallic acid. Electrosprayed parameters with high voltage (15 kV), low flow rate (0.1 mL/hr), and short distance (10 cm) exhibited a smaller diameter and spherical morphology. FT-IR showed interaction in the gallic acid-loaded zein nanoparticle by hydrogen bonds. Therefore, the electrospraying process is a feasible technique for obtaining gallic acid-loaded zein nanoparticles and providing potential protection to gallic acid from environmental factors.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/1750-3841.14486DOI Listing
April 2019

Microencapsulation of Carvacrol Using Pectin/Aloe-gel as a Novel Wound Dressing Films.

Curr Top Med Chem 2018 ;18(14):1261-1268

Departamento de Fisica, Universidad de Sonora, Unidad Centro, Apdo. postal 83000, Hermosillo, Sonora, Mexico.

Recently, Pectin (PEC) and Aloe-Gel (AG) have received great attention for their use in the encapsulation of hydrophobic bioactive compounds such as Carvacrol (CAR). The aim of this study is to assess the physical, chemical and biological properties of a novel PEC/AG film and evaluate its capability to entrap CAR into microencapsulates. For this purpose, the casting method was used to prepare the PEC/AG membranes (70:30 % w/w). The CAR-loaded PEC/AG film was prepared adding different proportions of CAR (0.25%, 0.50% and 1.00% v/v) to the mixture of PEC/AG, previously emulsified with tween 80 (1.0%). The optical properties, Water Vapor Permeability (WVP), ATR-FTIR spectroscopy, microstructure, antibacterial activity and size of microcapsules were evaluated. The PEC/AG membranes loaded with CAR showed yellowish appearance and they were transparent to the UV electromagnetic radiation (190, 200 and 280 nm). The film prepared with the lowest amount of CAR (PC/AG-CAR-0.25%) showed the highest values of WVP (66.2%) and, according to SEM micrograph, the largest microcapsules (≈1005± 39 µm3). The FTIR analysis showed the characteristic absorption peaks located at 1015 cm-1 to 1030 cm-1 and a small shoulder to 990 cm-1 of benzene ring 1:2:4 substituted that suggested the presence of CAR-loaded in the PC/AG film. On the other hand, E. coli O157:H7 showed the highest sensitivity to the PEC/AG-CAR-1.00% film, while S. aureus was not sensitive.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.2174/1568026618666180810141455DOI Listing
November 2018

Targeted Drug Delivery Via Human Epidermal Growth Factor Receptor for Sustained Release of Allyl Isothiocyanate.

Curr Top Med Chem 2018 ;18(14):1252-1260

Departamento de Física de la Materia Condensada, Facultad de Fisica, Universidad de Santiago de Compostela, Acurina, Spain.

In this study, allyl-isothiocyanate (AITC)-loaded Polylactic-Co-Glycolic Acid (PLGA) Nanoparticles (NPs) were prepared for targeting epithelial squamous carcinoma cells using a specific antibody targeting the Epidermal Growth Factor (EGF) receptor overexpressed on the cell membranes. AITC-loaded PLGA NPs showed more effective anticancer properties compared with free AITC, and their cytotoxicity was even more pronounced when the anti-EGFR antibody was covalently attached to the NPs surface. This targeting ability was additionally tested by co-culturing cervical HeLa cells, with very few EGFR on the membranes, and epithelial squamous carcinoma A431 cells, which largely overexpressed EFGR, being observed the specific localization of the antibody-functionalized AITC-loaded PLGA NPs solely in the latter types of cells, whereas non-functionalized NPs were distributed randomly in both cell types in much lesser extents. Thus, our findings support the development of drug delivery strategies that enhances the delivery of anti-cancer natural compounds to tumor tissue, in this case, by targeting specific tumor cell receptors with cell-specific ligands followed by tumor sensitization.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.2174/1568026618666180810150113DOI Listing
November 2018

Hybrid folic acid-conjugated gold nanorods-loaded human serum albumin nanoparticles for simultaneous photothermal and chemotherapeutic therapy.

Mater Sci Eng C Mater Biol Appl 2018 Oct 15;91:669-678. Epub 2018 Jun 15.

Departamento de Física, Posgrado en Nanotecnología, Universidad de Sonora, Rosales y Transversal, 83000 Hermosillo, Sonora, Mexico.

Hybrid nanoparticles containing both structural and functional nanocomponents might result in higher success and increased quality of life for patients suffering a disease such as cancer. In this study, we combine chemotherapy of conventional drug doxorubicin (Dox) with gold nanorods (AuNR) for photothermal therapy using multifunctional human serum albumin nanoparticles (HSA NP's) fabricated via desolvation technique with high efficiency. Folic acid (FA) was conjugated to HSA NP's trough an amidation via carbodiimide reaction for a more specific nanoplataform to HeLa cancer cells. The loading efficiency of Dox into AuNR loaded-HSA NP reached up to 2 μg Dox/mg HSA. The HSA-AuNR-Dox NP experienced photothermal heating varying laser potency (1, 0.5 and 0.2 W); reaching the bulk particle solution an increment of 16, 8 and 6 °C after 10 min of near-IR laser exposure respectively. When HeLa cells were treated with this multifunctional nanoplataform containing only AuNR, cancer cells experienced 96% cell viability without irradiation and 55% cell viability after just one irradiation session. When Dox is present in the nanoplataform, viability were 60% and 24% for non-irradiated and irradiated nanoplataforms, respectively. This study demonstrates that HSA-AuNR-Dox nanoparticles are suitable systems allowing a synergic chemo and phothothermal therapy.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.msec.2018.06.002DOI Listing
October 2018

Poly(lactic-co-glycolic acid) nanoparticles for sustained release of allyl isothiocyanate: characterization, in vitro release and biological activity.

J Microencapsul 2017 May 20;34(3):231-242. Epub 2017 Jun 20.

a Departamento de Física , Posgrado en Nanotecnología, Universidad de Sonora, Rosales y Transversal , Hermosillo , Sonora , México.

The objective of this study is to establish the ability of entrap allyl isothiocyanate (AITC) into polymeric nanoparticles to extend its shelf life and enhance its antiproliferative properties. Natural compounds, such as AITC, have showed multi-targeting activity resulting in a wide-range spectrum of therapeutic properties in chronic and degenerative diseases, conversely with most current pharmaceutical drugs showing single targeting activity and often result in drug resistance after extended administration periods. Apparently, AITC-loaded poly(lactic-co-glycolic acid) nanoparticles (PLGA NPs) reduced AITC degradation and volatility and were able to extend AITC shelf life compared with free AITC (65% vs. 20% in 24 h, respectively). Cell viability and uptake of AITC-loaded nanoparticles were studied in vitro, showing that the protection and sustained release of AITC from polymeric NPs involved a larger toxicity of tumoral cells. These nanoparticles could be used as protective systems for enhancing a biological activity.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1080/02652048.2017.1323037DOI Listing
May 2017

Oligomers, protofibrils and amyloid fibrils from recombinant human lysozyme (rHL): fibrillation process and cytotoxicity evaluation for ARPE-19 cell line.

Colloids Surf B Biointerfaces 2015 Feb 12;126:335-43. Epub 2014 Dec 12.

Departamento de Física, Universidad de Sonora, Rosales y Transversal, 83000 Hermosillo, Sonora, Mexico. Electronic address:

Amyloid-associated diseases, such Alzheimer's, Huntington's, Parkinson's, and type II diabetes, are related to protein misfolding and aggregation. Herein, the time evolution of scattered light intensity, hydrophobic properties, and conformational changes during fibrillation processes of rHL solutions at 55 °C and pH 2.0 were used to monitor the aggregation process of recombinant human lysozyme (rHL). Dynamic light scattering (DLS), thioflavin T (ThT) fluorescence, and surface tension (ST) at the air-water interface were used to analyze the hydrophobic properties of pre-amyloid aggregates involved in the fibrillation process of rHL to find a correlation between the hydrophobic character of oligomers, protofibrils and amyloid aggregates with the gain in cross-β-sheet structure, depending on the increase in the incubation periods. The ability of the different aggregates of rHL isolated during the fibrillation process to be adsorbed at the air-water interface can provide important information about the hydrophobic properties of the protein, which can be related to changes in the secondary structure of rHL, resulting in cytotoxic or non-cytotoxic species. Thus, we evaluated the cytotoxic effect of oligomers, protofibrils and amyloid fibrils on the cell line ARPE-19 using the MTT reduction test. The more cytotoxic protein species arose after a 600-min incubation time, suggesting that the hydrophobic character of pre-amyloid fibrils, in addition to the high prevalence of the cross-β-sheet conformation, can become toxic for the cell line ARPE-19.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.colsurfb.2014.12.008DOI Listing
February 2015

Complex self-assembly of reverse poly(butylene oxide)-poly(ethylene oxide)-poly(butylene oxide) triblock copolymers with long hydrophobic and extremely lengthy hydrophilic blocks.

J Phys Chem B 2014 May 1;118(19):5258-69. Epub 2014 May 1.

Departamento de Física de la Materia Condensada, Grupo de Física de Coloides y Polímeros , 15782-Santiago de Compostela, Spain.

Amphiphilic block copolymers have emerged during last years as a fascinating substrate material to develop micellar nanocontainers able to solubilize, protect, transport, and release under external or internal stimuli different classes of cargos to diseased cells or tissues. However, this class of materials can also induce biologically relevant actions, which complement the therapeutic activity of their cargo molecules through their mutual interactions with biologically relevant entities (cellular membranes, proteins, organelles...); these interactions at the same time, are regulated by the nature, conformation, and state of the copolymeric chains. For these reasons, in this paper we investigated the self-assembly process and physico-chemcial properties of two reverse triblock poly(butylene oxide)-poly(ethylene oxide)-poly(butylene oxide) block copolymers, BO14EO378BO14 and BO21EO385BO21, which have been recently found to be very useful as drug delivery nanovehicles and biological response modifiers under certain conditions (A. Cambón et al. Int. J. Pharm. 2013, 445, 47-57) in order to obtain a clear picture of the solution behavior of this class or block copolymers and to understand their biological activity. These block copolymers are characterized by possessing long BO blocks and extremely lengthy central EO ones, which provide them with a rich rheological behavior characterized by the formation of flowerlike micelles with sizes ranging from 20 to 40 nm in aqueous solution and the presence of intermicellar bridging even at low copolymers concentrations as denoted by atomic force microscopy. Bridging is also clearly observed by analyzing the rheological response of these block copolymers both storage and loss moduli upon changes on time, temperature, and or concentration. Strikingly, the relatively wide Poisson distribution of the polymeric chains make the present copolymers behave rather distinctly to conventional associative thickeners. The observed rich rheological behavior and their tunability also make these copolymers promising materials to configure drug gelling depots.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/jp500426kDOI Listing
May 2014

Interaction and cytotoxic effects of hydrophobized chitosan nanoparticles on MDA-MB-231, HeLa and Arpe-19 cell lines.

Curr Top Med Chem 2014 ;14(6):692-701

Departamento de Física, Universidad de Sonora, Rosales y Transversal, 83000 Hermosillo, Sonora, México.

In this work, we investigate the effect of chitosan hydrophobization on the internalization and cytotoxic effect of chitosan-based nanoparticles (NPs) on breast cancer cells (MDA-MB-231), cervical cancer cells (HeLa) and noncancer cells (Arpe-19). We also analyzed the interaction of NPs with a phospholipid (DPPC) membrane model at the airwater interface. An alkylation procedure to insert 8 carbon chains along the chitosan macromolecule with final 10 and 30 % substitution degrees was used. Nuclear magnetic resonance (NMR) and infrared spectroscopes (IR) were used to evaluate the success and extent of the hydrophobization procedure. Size, shape, and charge of NPs were evaluated by dynamic light scattering (DLS), atomic force microscope (AFM), and zeta potential, respectively. The effect of hydrophobicity on NPs was the reduction of the NPs average size, the formation of slightly elongated structures and the enhancing of the interaction of NPs with a DPPC monolayer at the air-water interface. By using fluorescence images on fluorescein-chitosan NPs, we observed a higher internalization of hydrophobic chitosan NPs in cancer cells in comparison with a low internalization of these NPs in normal cells. Even when non modified chitosan NPs were highly internalized in all cell lines, hydrophobized chitosan NPs showed a significantly higher cytotoxic effect on cancer cells in comparison with a lower effect showed by non-modified chitosan NPs on these cells. The cytotoxic effect on the normal cell line used was low for native chitosan NPs and negligible for hydrophobized chitosan NPs.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.2174/1568026614666140118214802DOI Listing
November 2014

Physicochemical characteristics of protein-NP bioconjugates: the role of particle curvature and solution conditions on human serum albumin conformation and fibrillogenesis inhibition.

Langmuir 2012 Jun 17;28(24):9113-26. Epub 2012 Apr 17.

Grupo de Física de Coloides y Polímeros, Departamento de Física de la Materia Condensada, Facultad de Física, Campus Vida, 15782, Universidad de Santiago de Compostela, Spain.

Gold nanoparticles (Au NPs) from 5 to 100 nm in size synthesized with HAuCl(4) and sodium citrate were complexed with the plasma protein human serum albumin (HSA). Size, surface charge, and surface plasmon bands of the Au NPs are largely modified by the formation of a protein corona via electrostatic interactions and hydrogen bonding as revealed by thermodynamic data. Negative values of the entropy of binding suggested a restriction in the biomolecule mobility upon adsorption. The structure of the adsorbed protein molecules is slightly affected by the interaction with the metal surface, but this effect is enhanced as the NP curvature decreases. Also, it is observed that the protein molecules adsorbed onto the NP surface are more resistant to complete thermal denaturation than free protein ones as deduced from the increases in the melting temperature of the adsorbed protein. Differences in the conformations of the adsorbed protein molecules onto small (<40 nm) and large NPs were observed on the basis of ζ-potential data and FTIR spectroscopy, also suggesting a better resistance of adsorbed protein molecules to thermal denaturing conditions. We think this enhanced protein stability is responsible for a reduced formation of HSA amyloid-like fibrils in the presence of small Au NPs under HSA fibrillation conditions.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/la300402wDOI Listing
June 2012

Micellisation of triblock copolymers of ethylene oxide and 1,2-butylene oxide: effect of B-block length.

J Colloid Interface Sci 2011 Sep 24;361(1):154-8. Epub 2011 May 24.

Departamento de Física de la Materia Condensada, Facultad de Física, Universidad de Santiago de Compostela, Spain.

We have used pyrene fluorescence spectroscopy and isothermal titration calorimetry (ITC) to investigate the effect of hydrophobic-block length on values of the critical micelle concentration (cmc) for aqueous solutions of triblock poly(butylene oxide)-poly(ethylene oxide)-poly(butylene oxide) block copolymers (B(n)E(m)B(n), where m and n denote the respective block lengths) with hydrophobic block lengths in the range n=12-21. Combined with results from previous work on B(n)E(m)B(n) copolymers with shorter B blocks, plots of log(10)(cmc) (cmc in molar units and reduced to a common E-block length) against total number of B units (n(t)=n for diblock or n(t)=2n for triblock copolymers) display transitions in the slopes of the two plots, which indicate changes in the micellisation equilibrium. These occur at values of n(t)which can be assigned to the onset and completion of collapse of the hydrophobic B blocks, an effect not previously observed for reverse triblock copolymers. The results are compared with related data for diblock E(m)B(n) copolymers.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jcis.2011.05.059DOI Listing
September 2011

One-dimensional magnetic nanowires obtained by protein fibril biotemplating.

Chemistry 2011 Jun 6;17(26):7366-73. Epub 2011 May 6.

Grupo de Física de Coloides y Polímeros, Departamento de Física de la Materia Condensada, Facultad de Física, Universidad de Santiago de Compostela, 15782 Santiago de Compostela, Spain.

Magnetic nanowires were obtained through the in situ synthesis of magnetic material by Fe-controlled nanoprecipitation in the presence of two different protein (human serum albumin (HSA) and lysozyme (Lys)) fibrils as biotemplating agents. The structural characteristics of the biotemplates were transferred to the hybrid magnetic wires. They exhibited excellent magnetic properties as a consequence of the 1D assembly and fusion of magnetite nanoparticles as ascertained by SQUID magnetometry. Prompted by these findings, we also checked their potential applicability as MRI contrast agents. The magnetic wires exhibited large r(2)* relaxivities and sufficient contrast resolution even in the presence of an extremely small amount of Fe in the magnetic hybrids, which would potentially enable their use as T(2) contrast imaging agents.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/chem.201003679DOI Listing
June 2011

Modulation of size and shape of Au nanoparticles using amino-X-shaped poly(ethylene oxide)-poly(propylene oxide) block copolymers.

J Phys Chem B 2010 Jan;114(1):66-76

Grupo de Física de Coloides y Polímeros, Departamento de Física de la Materia Condensada, Facultad de Física, Universidad de Santiago de Compostela, E-15782, Santiago de Compostela, Spain.

In the present work, the formation and stabilization of gold nanoparticles in a one-pot water-based synthesis has been achieved in the presence of a four-arm, star-shaped polyoxyethyelene-polyoxypropylene (PEO-PPO) block copolymer, Tetronic T904, which acts as both reductant and stabilizer. The influence of several parameters such as copolymer and gold salt concentration, reaction temperature, and solution pH on both the size and shape of the resulting nanocrystals has been established. Low copolymer/gold salt molar ratios favor the formation of either triangular or hexagonal planar nanostructures due to a low reduction rate which turns the reaction into kinetic control. As the molar ratio increases, reduction becomes faster with the subsequent increase in the number of crystal seeds and, thus, the decrease in particle size. In addition, there is an increase in the reduction rate which causes the reduction reaction to be governed by thermodynamics, and consequently, spherical geometries are favored. A particle spherical shape can also be promoted as a consequence of the accumulation of block copolymer molecules on different crystallographic planes, homogenizing the metal surface structure and disabling the growth in different crystallographic directions. The same behavior was observed when the reaction temperature was raised. The size and shape of gold nanoparticles could also be controlled by varying the pH of the medium. As the pH becomes more acidic, protons prevent the oxyethylene part of the copolymer from the reduction of metal ions, and consequently, the number of nuclei decreases. This explains the overall increase in the particle size and the change in shape when the synthesis is carried out in acid medium. Finally, comparison with nanoparticles obtained in the presence of a structurally related linear block copolymer Pluronic P105, with a similar number of EO and PO units as T904, denoted an important incidence of the arrangement of PEO and PPO blocks on the reduction reaction rate and the size and shape of the resulting nanoparticles.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/jp908569zDOI Listing
January 2010

Additional supra-self-assembly of human serum albumin under amyloid-like-forming solution conditions.

J Phys Chem B 2009 Sep;113(36):12391-9

Grupo de Fisica de Coloides y Polimeros, Departamento de Fisica de la Materia Condensada, Facultad de Fisica, Universidad de Santiago de Compostela, E-15782 Santiago de Compostela, Spain.

Protein aggregation has a multitude of consequences ranging from affecting protein expression to its implication in different diseases. Of recent interest is the specific form of aggregation leading to the formation of amyloid fibrils, structures associated with diseases such as Alzheimer's disease. These fibrils can further associate in other more complex structures such as fibrillar gels, plaques, or spherulitic structures. In the present work, we describe the physical and structural properties of additional supraself-assembled structures of human serum albumin under solution conditions in which amyloid-like fibrils are formed. We have detected the formation of ordered aggregates of amyloid fibrils, i.e., spherulites which possess a radial arrangement of the fibrils around a disorganized protein core and sizes of several micrometers by means of polarized optical microscopy, laser confocal microscopy, and transmission electron microscopy. These spherulites are detected both in solution and embedded in an isotropic matrix of fibrillar gels. In this regard, we have also noted the formation of protein gels when the protein concentration and/or ionic strength exceds a threshold value (the gelation point) as observed by rheometry. Fibrillar gels are formed through intermolecular nonspecific association of amyloid fibrils at a pH far away from the isolectric point of the protein where protein molecules seem to display a "solid-like" behavior due to the existence of non-DLVO (Derjaguin-Landau-Verwey-Overbeck) intermolecular repulsive forces. As the solution ionic strength increases, a coarsening of this type of gel is observed by environmental scanning microscopy. In contrast, at pH close to the protein isoelectric point, particulate gels are formed due to a faster aggregation process, which does not allow substantial structural reorganization to enable the formation of ordered structures. This behavior also additionally corroborates that the existence of particulates might also be a generic property of all polypeptide chains as amyloid fibril formation under suitable conditions.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/jp904167eDOI Listing
September 2009

Influence of electrostatic interactions on the fibrillation process of human serum albumin.

J Phys Chem B 2009 Jul;113(30):10521-9

Grupo de Física de Coloides y Polímeros, Departamento de Física de la Materia Condensada, Facultad de Física, Universidad de Santiago de Compostela, E-15782, Santiago de Compostela, Spain.

The fibrillation propensity of the multidomain protein human serum albumin (HSA) has been analyzed under physiological and acidic conditions at room and elevated temperatures with varying ionic strengths by different spectroscopic techniques. The kinetics of fibril formation under the different solution conditions and the structures of resulting fibrillar aggregates were also determined. In this way, we have observed that fibril formation is largely affected by electrostatic shielding: at physiological pH, fibrillation is progressively more efficient and faster in the presence of up to 50 mM NaCl; meanwhile, at larger salt concentrations, excessive shielding and further enhancement of the solution hydrophobicity might involve a change in the energy landscape of the aggregation process, which makes the fibrillation process difficult. In contrast, under acidic conditions, a continuous progressive enhancement of HSA fibrillation is observed as the electrolyte concentration in solution increases. Both the distinct ionization and initial structural states of the protein before incubation may be the origin of this behavior. CD, FT-IR, and tryptophan fluorescence spectra seem to confirm this picture by monitoring the structural changes in both protein tertiary and secondary structures along the fibrillation process. On the other hand, the fibrillation of HSA does not show a lag phase except at pH 3.0 in the absence of added salt. Finally, differences in the structure of the intermediates and resulting fibrils under the different conditions are also elucidated by TEM and FT-IR.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/jp902224dDOI Listing
July 2009

Existence of different structural intermediates on the fibrillation pathway of human serum albumin.

Biophys J 2009 Mar;96(6):2353-70

Grupo de Física de Coloides y Polímeros, Departamento de Física de la Materia Condensada, Facultad de Física, Universidad de Santiago de Compostela, Santiago de Compostela, Spain.

The fibrillation propensity of the multidomain protein human serum albumin (HSA) was analyzed under different solution conditions. The aggregation kinetics, protein conformational changes upon self-assembly, and structure of the different intermediates on the fibrillation pathway were determined by means of thioflavin T (ThT) fluorescence and Congo Red absorbance; far- and near-ultraviolet circular dichroism; tryptophan fluorescence; Fourier transform infrared spectroscopy; x-ray diffraction; and transmission electron, scanning electron, atomic force, and microscopies. HSA fibrillation extends over several days of incubation without the presence of a lag phase, except for HSA samples incubated at acidic pH and room temperature in the absence of electrolyte. The absence of a lag phase occurs if the initial aggregation is a downhill process that does not require a highly organized and unstable nucleus. The fibrillation process is accompanied by a progressive increase in the beta-sheet (up to 26%) and unordered conformation at the expense of alpha-helical conformation, as revealed by ThT fluorescence and circular dichroism and Fourier transform infrared spectroscopies, but changes in the secondary structure contents depend on solution conditions. These changes also involve the presence of different structural intermediates in the aggregation pathway, such as oligomeric clusters (globules), bead-like structures, and ring-shaped aggregates. We suggest that fibril formation may take place through the role of association-competent oligomeric intermediates, resulting in a kinetic pathway via clustering of these oligomeric species to yield protofibrils and then fibrils. The resultant fibrils are elongated but curly, and differ in length depending on solution conditions. Under acidic conditions, circular fibrils are commonly observed if the fibrils are sufficiently flexible and long enough for the ends to find themselves regularly in close proximity to each other. These fibrils can be formed by an antiparallel arrangement of beta-strands forming the beta-sheet structure of the HSA fibrils as the most probable configuration. Very long incubation times lead to a more complex morphological variability of amyloid mature fibrils (i.e., long straight fibrils, flat-ribbon structures, laterally connected fibers, etc.). We also observed that mature straight fibrils can also grow by protein oligomers tending to align within the immediate vicinity of the fibers. This filament + monomers/oligomers scenario is an alternative pathway to the otherwise dominant filament + filament manner of the protein fibril's lateral growth. Conformational preferences for a certain pathway to become active may exist, and the influence of environmental conditions such as pH, temperature, and salt must be considered.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.bpj.2008.12.3901DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2907680PMC
March 2009

Self-assembly process of different poly(oxystyrene)-poly(oxyethylene) block copolymers: spontaneous formation of vesicular structures and elongated micelles.

Langmuir 2008 Jul 12;24(14):7107-16. Epub 2008 Jun 12.

Departamento de Investigación en Polímeros y Materiales y Departamento de Física, Universidad de Sonora, Sorales Resales y Transversal, 83000 Hermosillo Sonora, Mexico.

In the present work, we investigated the micellization, gelation, and structure of the aggregates of three poly(ethylene oxide)-polystyrene oxide block copolymers (E12S10, E10S10E10, and E137S18E137, where E denotes ethylene oxide and S styrene oxide and the subscripts the block length) in solution. Two of them have similar block lengths but different structures (E12S10 and E10S10E10) and the other has longer blocks (E137S18E137). For the first time, the spontaneous formation of vesicles by a poly(oxystyrene)-poly(oxyethylene) block copolymer is reported. These vesicular structures are present when copolymer E12S10 self-assembles in aqueous solution in coexistence with spherical micelles, as confirmed by the size distribution obtained by dynamic light scattering and pictures obtained by polarized optical microscopy, and transmission and cryo-scanning electron microscopies. Vesicle sizes vary between 60 and 500 nm. On the other hand, for copolymers E10S10E10 and E137S18E137, only one species is found in solution, which is assigned to elongated and spherical micelles, respectively. If we compare the high aggregation number derived by static light scattering for the triblock block copolymer micelles, with the maximum theoretical micellar dimensions compatible with a spherical geometry, we can see that the micellar geometry cannot be spherical but must be elongated. This is corroborated by transmission electron microscopy images. On the other hand, tube inversion was used to define the mobile-immobile (soft-hard gel) phase boundaries. To refine the phase diagram and observe the existence of additional phases, rheological measurements of copolymer E137S18E137 were done. The results are in good agreement with previous values published for other polystyrene oxide-poly(ethylene oxide) block copolymers. In contrast, copolymers E12S10 and E10S10E10 did not gel in the concentration range analyzed. Thus, only certain concentrations of copolymer E10S10E10 were analyzed by rheometry, for which an upturn in the low-frequency range of the stress moduli was observed, denoting an evidence of an emerging slow process, which we assign to the first stages of formation of an elastic network.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/la8004568DOI Listing
July 2008

Influence of external factors on the micellization process and aggregate structure of poly(oxy)styrene-poly(oxy)ethylene block copolymers.

J Phys Chem B 2008 May 8;112(17):5296-304. Epub 2008 Apr 8.

Grupo de Física de Coloides y Polímeros, Grupo de Sistemas Complejos, Departamento de Física de la Materia Condensada, Facultad de Física, Universidad de Santiago de Compostela, Santiago de Compostela, Spain.

Solutions of the polyoxystyrene-polyoxyethylene block copolymer SO(17)EO(65), where SO denotes polystyrene oxide block as the hydrophobic block and EO the polyethylene oxide block as the hydrophilic block, in mixtures of water (a selective solvent for the EO blocks) and 1,4-dioxane (a good solvent for both blocks) were studied by surface tension and light scattering measurements. Surface and micellar structural parameters have been analyzed as a function of solvent composition. The critical micelle concentration increases and the micellar aggregation number decreases, respectively, as the amount of 1,4-dioxane in the binary solvent increases as a consequence of the enhanced solubility of the SO blocks in the solvent mixture, causing the lowering of the interfacial tension between the hydrophobic blocks in the micellar core and the solvent; therefore, to achieve thermodynamic equilibrium, the micelle size decreases. In addition, static light scattering (SLS) has been proved to be a useful technique to detect the lower boundary of the transition between a dilute micellar solution (sol) to a local-ordered micellar solution (soft gel) resulting from a percolation mechanism. Comparison of the sol-soft gel boundaries obtained from SLS for copolymers SO(17)EO(65) and EO(67)SO(15)EO(67) with those previously derived by rheology is made. Finally, changes in the autocorrelation function of the solutions at the boundary obtained from dynamic light scattering are also analyzed.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/jp7112895DOI Listing
May 2008

Chitosan-cholesterol and chitosan-stearic acid interactions at the air-water interface.

Biomacromolecules 2005 Sep-Oct;6(5):2416-26

Departamento de Investigación en Materiales, Universidad de Sonora, Rosales y transversal, C. P. 83000 Hermosillo, Sonora, México.

We report in this work the isotherms of cholesterol and stearic acid at the air-water interface modified by different chitosans (chitosan chloride, hydrophobic modified chitosan, and medium and high molecular weight chitosans) in the aqueous subphase. The Langmuir-Blodgett films of the complexes cholesterol-chitosan and stearic acid-chitosan are analyzed by atomic force microscopy (AFM), and a molecular simulation was performed to visualize the chitosan-lipid interactions. Strong modifications are obtained in the isotherms as a result of the chitosan interactions with cholesterol and stearic acid at the air-water interface. These modifications were dependent on the type and concentration of chitosan. Severe modifications of all phases were noticed with larger molecular areas, and the observed changes in the compressional modulus were dependent on the type of chitosan used. The complexes of chitosan-stearic acid were more flexible than the ones of chitosan-cholesterol. The AFM images demonstrated that chitosan was disaggregated by the cholesterol and stearic acid interactions producing more homogeneous surfaces in some cases. The hydrophobic chitosan showed more affinity with stearic acid, while both medium and high molecular weight chitosans produced homogeneous surfaces with cholesterol. The simulated chitosan chains interacting with cholesterol and stearic acid demonstrated the possibility of specific sites of electrostatic bonds between these molecules. Adsorption of cholesterol on the different powdered chitosans, performed by HPLC, showed that the medium and high molecular weight chitosans could retain higher proportions of cholesterol compared with the other analyzed samples.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/bm050106sDOI Listing
December 2005