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1.
Chemosphere ; 253: 126720, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32464762

RESUMO

To understand the biofilm formation of biofilm-based processes in wastewater treatment plants (WWTPs), the interaction mechanisms between extracted extracellular polymeric substances (EPS) and three model carrier surfaces (i.e., negatively charged hydrophilic silica, positively charged hydrophilic alumina, and neutral charged hydrophobic polystyrene) were investigated employing a laboratory quartz crystal microbalance with dissipation monitoring equipment (QCM-D) and an atomic force microscope (AFM). The data suggested that surface charge and hydrophobicity of both EPS and carriers played significant roles in the interaction behaviors. Moreover, increases in ionic strength could lead to the increasing zeta potential and hydrophobicity of EPS. It is worth noting that long-range DLVO forces dominated the EPS deposition on carriers in lower ionic strength while short-range Lewis acid-base (AB) interaction controlled the adhesion behaviors in higher ionic strength. Besides, the presence of calcium ions contributed to the adhesion behaviors because of strong charge neutralization and hydrophobic effect. Bound EPS (BEPS) showed higher affinity to model carriers than dissolved EPS (DEPS), which conformed to XDLVO prediction rather than classical DLVO model. Overall, these results provide insights into the influence mechanisms of carrier characteristics, ionic strength, calcium ion and EPS components on the interaction between EPS and representative carriers, contributing to predict and regulate biofilm formation in biofilm-based processes.


Assuntos
Matriz Extracelular de Substâncias Poliméricas , Eliminação de Resíduos Líquidos , Biofilmes , Interações Hidrofóbicas e Hidrofílicas , Íons , Modelos Químicos , Concentração Osmolar , Técnicas de Microbalança de Cristal de Quartzo , Esgotos , Dióxido de Silício/química , Águas Residuárias
2.
J Vis Exp ; (158)2020 04 11.
Artigo em Inglês | MEDLINE | ID: mdl-32338648

RESUMO

Fundamentals of inorganic-organic interactions are critically important in the discovery and development of novel biointerfaces amenable for utilization in biotechnology and medicine. Recent studies indicate that proteins interact with surfaces through limited adsorption sites. Protein fragments such as amino acids and peptides can be used for interaction modeling between complex biological macromolecules and inorganic surfaces. During the last three decades, many valid and sensitive methods have been developed to measure the physical chemistry fundamentals of those interactions: isothermal titration calorimetry (ITC), surface plasmon resonance (SPR), quartz crystal microbalance (QCM), total internal reflection fluorescence (TIRF), and attenuated total reflectance spectroscopy (ATR). The simplest and most affordable technique for the measurement of adsorption is the depletion method, where the change in sorbate concentration (depletion) after contact with solution-dispersed sorbent is calculated and assumed to be adsorbed. Adsorption isotherms based on depletion data provide all basic physicochemical data. However, adsorption from solutions requires longer equilibration times due to kinetic restrictions and sorbents with a high specific surface area, making it almost inapplicable to macroscopic fixed plane surfaces. Moreover, factors such as the instability of sols, nanoparticle aggregates, sorbent crystallinity, nanoparticle size distribution, pH of the solution, and competition for adsorption, should be considered while studying adsorbing peptides. Depletion data isotherm construction provides comprehensive physical chemistry data for literally every soluble sorbate yet remains the most accessible methodology, as it does not require expensive setups. This article describes a basic protocol for the experimental study of peptide adsorption on inorganic oxide and covers all critical points that affect the process.


Assuntos
Adsorção/fisiologia , Nanopartículas/química , Peptídeos/química , Técnicas de Microbalança de Cristal de Quartzo , Propriedades de Superfície
3.
Environ Sci Technol ; 54(8): 4876-4885, 2020 04 21.
Artigo em Inglês | MEDLINE | ID: mdl-32186175

RESUMO

Plastic materials contain various additives, which can be released during the entire lifespan of plastics and pose a threat to the environment and human health. Despite our knowledge on leakage of additives from products, accurate and rapid approaches to study emission kinetics are largely lacking, in particular, methodologies that can provide in-depth understanding of polymer/additive interactions. Here, we report on a novel approach using quartz crystal microbalance (QCM) to measure emissions of additives to water from polymer films spin-coated on quartz crystals. The methodology, being accurate and reproducible with a standard error of ±2.4%, was applied to a range of organophosphate esters (OPEs) and polymers with varying physicochemical properties. The release of most OPEs reached an apparent steady-state within 10 h. The release curves for the studied OPEs could be fitted using a Weibull model, which shows that the release is a two-phase process with an initial fast phase driven by partitioning of OPEs readily available at or close to the polymer film surface, and a slower phase dominated by diffusion in the polymer. The kinetics of the first emission phase was mainly correlated with the hydrophobicity of the OPEs, whereas the diffusion phase was weakly correlated with molecular size. The developed QCM-based method for assessing and studying release of organic chemicals from a polymeric matrix is well suited for rapid screening of additives in efforts to identify more sustainable replacement polymer additives with lower emission potential.


Assuntos
Polímeros , Técnicas de Microbalança de Cristal de Quartzo , Ésteres , Humanos , Organofosfatos , Quartzo , Água
4.
J Vis Exp ; (155)2020 01 22.
Artigo em Inglês | MEDLINE | ID: mdl-32065145

RESUMO

In this study, we present various examples of how thin film preparation for quartz crystal microbalance experiments informs the appropriate modeling of the data and determines which properties of the film can be quantified. The quartz crystal microbalance offers a uniquely sensitive platform for measuring fine changes in mass and/or mechanical properties of an applied film by observing the changes in mechanical resonance of a quartz crystal oscillating at high frequency. The advantages of this approach include its experimental versatility, ability to study changes in properties over a wide range of experimental time lengths, and the use of small sample sizes. We demonstrate that, based on the thickness and shear modulus of the layer deposited on the sensor, we can acquire different information from the material. Here, this concept is specifically exploited to display experimental parameters resulting in mass and viscoelastic calculations of adsorbed collagen on gold and polyelectrolyte complexes during swelling as a function of salt concentration.


Assuntos
Proteínas/química , Técnicas de Microbalança de Cristal de Quartzo/métodos , Adsorção
5.
J Oleo Sci ; 69(3): 271-276, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-32051359

RESUMO

In this study, we investigated the direct detection of DNA, without pretreatment, using a quartz crystal microbalance (QCM) sensor. This sensor is modified by a self-assembled monolayer of a thiol derivative that has an amino group as the terminal functional group. Contact angle values and the attenuated total reflectance Fourier transform infrared (ATR/FT-IR) spectra of the QCM sensors after immersion into an ethanol solution of thiol derivatives clearly showed that self-assembled monolayers of the derivatives were formed on the QCM sensors. Although QCM measurements using unmodified and carboxylic group-modified sensors could not detect DNA-Na salt, the sensor modified with amino groups could detect the DNA. This system can be used for the analysis of the interaction between DNA and DNAbinding proteins.


Assuntos
DNA/análise , Técnicas de Microbalança de Cristal de Quartzo/métodos , Compostos de Sulfidrila/química , Etanol , Psicoterapia Breve , Espectroscopia de Infravermelho com Transformada de Fourier
6.
Chem Commun (Camb) ; 56(18): 2691-2694, 2020 Mar 04.
Artigo em Inglês | MEDLINE | ID: mdl-32051985

RESUMO

A conductive polymer thin film having choline phosphate as the side group was prepared. Quartz crystal microbalance (QCM) was employed to evaluate the adsorption of the model protein, bovine serum albumin (BSA), on the films deposited on indium tin oxide (ITO) electrodes. Cell adsorption on the film was evaluated by a fibroblast NIH3T3.


Assuntos
Fosforilcolina/química , Polímeros/química , Soroalbumina Bovina/química , Adsorção , Animais , Bovinos , Condutividade Elétrica , Eletrodos , Camundongos , Estrutura Molecular , Células NIH 3T3 , Imagem Óptica , Polímeros/síntese química , Técnicas de Microbalança de Cristal de Quartzo , Propriedades de Superfície , Compostos de Estanho/química
7.
Chemosphere ; 247: 125876, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31978652

RESUMO

Aluminium oxide nanoparticles (Al2O3 NPs) potentially cause health hazards after their release into the environment. The crystalline phase of Al2O3 NPs determines their surface structure and the number of functional groups. The adsorption of natural organic matter (NOM) or biomolecules on the surface Al2O3 NPs also alters their surface properties and subsequent interactions with organisms. In this study, the roles of the Al2O3 crystalline phase and the surface coating of the nanoparticles on the membrane integrity and fluidity were investigated. Giant and small unilamellar vesicles (GUVs and SUVs) were prepared as model cell membranes to detect membrane disruption after exposure to Al2O3 NPs. Due to amorphous structure and high surface activity of γ-Al2O3 NPs, they had a stronger affinity with the membrane and caused more serious membrane rupture than that of α-Al2O3 NPs. The deposition of Al2O3 NPs on the membrane and the induced membrane disruption were monitored by a quartz crystal microbalance with dissipation (QCM-D) method. HA-coated Al2O3 NPs disrupted the SUV layer on the QCM-D sensor, while BSA-coated Al2O3 NPs only adhered to the membrane and induced unremarkable vesicle disruption. In addition, untreated γ-Al2O3 NPs induced remarkable gelation of a negatively charged membrane, but other types of Al2O3 NPs caused negligible membrane phase changes. The outcomes of this study demonstrate that the crystalline phase of the Al2O3 NPs affects the integrity and fluidity of cell membranes. The protein coatings on the NPs weaken the NP-membrane interaction, while HA coatings increase the damage of the NP-induced interaction.


Assuntos
Óxido de Alumínio/química , Modelos Químicos , Nanopartículas/química , Adsorção , Membrana Celular , Coloides , Excipientes , Técnicas de Microbalança de Cristal de Quartzo , Propriedades de Superfície
8.
Biophys Chem ; 258: 106329, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-31954222

RESUMO

Viscoelastic properties of molecular assemblies formed by mixing poly (l-lysine) (PLL) and poly (l-glutamic acid) (PGA) at pH = 7.5 have been studied using Quartz crystal microbalance with dissipation (QCM-D). The inter-molecular complex between PLL and PGA arising from strong electrostatic interaction, leads to local changes in secondary structure resulting in intra-molecular complexes. ATR-FTIR analysis of the Secondary structural features of PLL, suggest an abundance of anti-parallel beta sheet that causes a significant change in the morphology of the self-assembled structures. A combination of spectroscopy, Brewster angle microscopy (BAM), Transmission electron and scanning electron microscopy show that an inverse relationship exists between the elasticity of the different PLL + PGA mixed films and the % anti parallel beta sheet conformation. The elastic moduli for the mixtures change from about 0.913 ± 0.01 GPa for pure PLL to about 0.764 ± 0.01 GPa in the mixture when PGA increases. The localized breaking and reformation of the ion pairs in the complex control their sizes and show an inverse relationship with the elastic moduli. The rheological profiles of the films, elastic moduli, together with their surface morphology from microscopy (TEM) and (SEM) confirmed their increasing propensity to self-assemble in one dimension to form tapes, colloidal particles and their composite assemblies.


Assuntos
Elasticidade , Peptídeos/química , Ar , Modelos Moleculares , Tamanho da Partícula , Conformação Proteica , Técnicas de Microbalança de Cristal de Quartzo , Espectroscopia de Infravermelho com Transformada de Fourier
9.
Chem Commun (Camb) ; 56(4): 591-594, 2020 Jan 14.
Artigo em Inglês | MEDLINE | ID: mdl-31830154

RESUMO

The interaction between an aMOC and miRNA/DNA is studied and the use of a signal probe DNA (spDNA)@aMOC complex as an effective amplifier in a QCM sensor to detect miRNA is developed. The signal can be significantly enhanced, which leads to improved performance when detecting and distinguishing miRNAs.


Assuntos
Técnicas Biossensoriais , DNA/química , Estruturas Metalorgânicas/química , MicroRNAs/química , Técnicas de Microbalança de Cristal de Quartzo , Estrutura Molecular , Tamanho da Partícula , Porosidade , Propriedades de Superfície
10.
Food Chem ; 309: 125787, 2020 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-31771917

RESUMO

In this study, a novel detection method of methimazole was proposed based on the hollow molecularly imprinted quartz crystal microbalance (QCM) sensor, in which the hollow imprinted polymers (H-MIPs) were firstly prepared through the surface imprinted techniques, using hollow silica spheres as matrix supporting material and methimazole as template molecule. The characterizations of H-MIPs were carefully studied. Compared with traditional MIPs, H-MIPs exhibited faster mass transfer rate and higher adsorption capacity. After coating onto the surface of Au chip, the H-MIPs QCM sensor was fabricated. Based on the frequency shift, good linear behavior in the range of 5-70 µg L-1, limit of detection of 3 µg L-1, and good recoveries of 88.32%-107.96% in the spiked pork, beef and milk were obtained. The analysis process could complete within 8 min. The developed sensor provided an effective, fast and accurate method for the methimazole detection in food samples.


Assuntos
Metimazol/análise , Impressão Molecular , Polímeros/química , Técnicas de Microbalança de Cristal de Quartzo/métodos , Animais , Contaminação de Alimentos/análise , Ouro/química , Limite de Detecção , Carne/análise , Leite/química
11.
Anal Chim Acta ; 1095: 212-218, 2020 Jan 25.
Artigo em Inglês | MEDLINE | ID: mdl-31864625

RESUMO

Sensitive and selective detection of miRNA is of great significance for the early diagnosis of human diseases, especially for cancers. Quartz crystal microbalance (QCM) is an effective tool for detecting biological molecules; however, the application of QCM for miRNA detection is still very limited. One of the great needs for QCM detection is to further improve the QCM signal. Herein, for the first time, we promote a new signal enhancement strategy for the detection of miRNA by QCM. First, a hairpin biotin-modified DNA was used as a probe DNA, which exposes the biotin site when interacting with target miRNA. Then, a streptavidin@metal-organic framework (SA@MOF) complex formed by electrostatic attractions between SA and a MOF was introduced into the QCM detection system. The SA@MOF complexes serve as both a signal amplifier and a specific recognition element via specific biotin-SA interactions. The strategy was applied to the detection of a colorectal cancer marker, miR-221, by using a stable Zr(IV)-MOF, UiO-66-NH2. The detection linear range was 10 fM-1 nM, the detection limit was 6.9 fM, and the relative standard deviation (RSD) (n = 5) was lower than 10% in both simulated conditions and the real serum environment. Furthermore, the detection limit reached 0.79 aM when coupled with the isothermal exponential amplification reaction (EXPAR).


Assuntos
Estruturas Metalorgânicas/química , MicroRNAs/análise , Estreptavidina/química , Animais , Técnicas Biossensoriais/métodos , Biotina/química , Bovinos , DNA/química , DNA/genética , Sondas de DNA/química , Sondas de DNA/genética , Limite de Detecção , MicroRNAs/genética , Técnicas de Amplificação de Ácido Nucleico/métodos , Hibridização de Ácido Nucleico , Técnicas de Microbalança de Cristal de Quartzo/métodos
12.
Int J Nanomedicine ; 14: 9047-9061, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31819418

RESUMO

Background: Posterior capsular opacification (PCO) is the main complication after intraocular lens (IOL) implantation in cataract surgery, which is the result of lens epithelial cell (LEC) adhesion, proliferation and migration on the IOL and at the lens capsule interface. Hydrophilic surface modification, such as surface heparinization, decreases the cell adhesion, which has been commercialized and used clinically. However, clinical long-term observation results show no significant difference between the pristine and heparinized IOLs. Methods: To prevent PCO over the long time span, we modified the IOLs with an antiproliferative drug-loaded hydrophilic coating. The antiproliferative drug doxorubicin (DOX)-incorporated chitosan (CHI) nanoparticle was fabricated by sodium tripolyphosphate (TPP) gelation. Such antiproliferative drug-loaded CHI-TPP-DOX nanoparticles (CTDNP) were used as one of the building blocks to prepare polyelectrolyte multilayer with heparin (HEP) via layer-by-layer assembly, obtaining (HEP/CTDNP)n multilayers. The assembly process was characterized by quartz crystal microbalance with dissipation (QCM-D). The drug release behavior of the coating was investigated by ultra-HPLC (UPLC). In vitro cell experiments were carried out to monitor the effects of multifunctional coatings on cellular adhesion, proliferation and migration. And the intraocular implantation was performed on rabbits to evaluate the in vivo PCO inhibitory effect of such surface-functionalized IOLs. Results: The positively charged CTDNP was successfully prepared by ionic gelation. The QCM-D results indicate the successful preparation of the (HEP/CTDNP)n multilayer film. Drug release profiles showed that surface-multifunctionalized IOL had drug-sustained release properties. In vitro cell culture results showed significant inhibition of adhesion, proliferation and migration of LECs after surface modification. The in vivo results showed that the IOLs with multifunctionalized surface can effectively reduce the posterior hyperplasia and Soemmering's ring (SR) formation. Conclusion: These findings suggested that such multifunctionalized drug-eluting IOLs can effectively reduce the posterior hyperplasia and SR formation when intraocular implantation has a major impact on reducing PCO incidence. Thus they have a great potential in improving patient vision recovery and maintenance.


Assuntos
Catarata/patologia , Lentes Intraoculares , Cápsula Posterior do Cristalino/patologia , Adesivos/farmacologia , Animais , Adesão Celular/efeitos dos fármacos , Linhagem Celular , Movimento Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Forma Celular/efeitos dos fármacos , Quitosana/química , Doxorrubicina/farmacologia , Liberação Controlada de Fármacos , Células Epiteliais/efeitos dos fármacos , Células Epiteliais/patologia , Humanos , Interações Hidrofóbicas e Hidrofílicas , Masculino , Nanopartículas/química , Tamanho da Partícula , Cápsula Posterior do Cristalino/efeitos dos fármacos , Técnicas de Microbalança de Cristal de Quartzo , Coelhos , Eletricidade Estática , Propriedades de Superfície
13.
Int J Mol Sci ; 21(1)2019 Dec 19.
Artigo em Inglês | MEDLINE | ID: mdl-31861692

RESUMO

Heat shock proteins play roles in assisting other proteins to fold correctly and in preventing the aggregation and accumulation of proteins in misfolded conformations. However, the process of aging significantly degrades this ability to maintain protein homeostasis. Consequently, proteins with incorrect conformations are prone to aggregate and accumulate in cells, and this aberrant aggregation of misfolded proteins may trigger various neurodegenerative diseases, such as Parkinson's disease. Here, we investigated the possibilities of suppressing α-synuclein aggregation by using a mutant form of human chaperonin Hsp60, and a derivative of the isolated apical domain of Hsp60 (Hsp60 AD(Cys)). In vitro measurements were used to detect the effects of chaperonin on amyloid fibril formation, and interactions between Hsp60 proteins and α-synuclein were probed by quartz crystal microbalance analysis. The ability of Hsp60 AD(Cys) to suppress α-synuclein intracellular aggregation and cytotoxicity was also demonstrated. We show that Hsp60 mutant and Hsp60 AD(Cys) both effectively suppress α-synuclein amyloid fibril formation, and also demonstrate for the first time the ability of Hsp60 AD(Cys) to function as a mini-chaperone inside cells. These results highlight the possibility of using Hsp60 AD as a method of prevention and treatment of neurodegenerative diseases.


Assuntos
Chaperonina 60/química , Chaperonina 60/farmacologia , Proteínas Mitocondriais/química , Proteínas Mitocondriais/farmacologia , Agregados Proteicos/efeitos dos fármacos , alfa-Sinucleína/metabolismo , Sítios de Ligação , Linhagem Celular , Chaperonina 60/genética , Humanos , Proteínas Mitocondriais/genética , Modelos Moleculares , Mutação , Ligação Proteica , Domínios Proteicos , Técnicas de Microbalança de Cristal de Quartzo , alfa-Sinucleína/química , alfa-Sinucleína/efeitos dos fármacos
14.
Analyst ; 144(23): 6936-6943, 2019 Nov 18.
Artigo em Inglês | MEDLINE | ID: mdl-31617512

RESUMO

MicroRNAs (miRNAs) are small non-coding RNA molecules that serve as important biomarkers for a variety of diseases such as cancer and vascular disease. However, sensitive and accurate detection of miR-21 is very challenging in that up-regulation of miR-21 is highly associated with several types of malignant tumors. Here, quartz crystal microbalance (QCM) biosensors were developed for sensitive and specific detection of miR-21 through formation of miR-21-DNA hybrid duplexes and non-specific intercalation of surface-modified pyrene molecules. High selectivity for miR-21 over other miRNAs came from the specific hybridization between miR-21 and gold nanoparticle (AuNP)-conjugated complementary oligonucleotides of miR-21. High sensitivity was obtained through formation of intercalated complexes on the surface with subsequent gold staining signal amplification. Under optimum condition using this strategic approach, our novel QCM biosensors could detect miR-21 concentration as low as 3.6 pM in the entire linear range from 2.5 pM to 2.5 µM with a correlation coefficient of 0.989. In addition, these sensors did not work at all for other miRNAs based on their high selectivity. miR-21 in human brain total RNA and total RNA extracted from A549 cell line could also be successfully detected. Therefore, miRNA detection technology using QCM biosensors and their detection mechanisms have potential as alternatives in biological studies and clinical diagnosis.


Assuntos
DNA/química , Substâncias Intercalantes/química , MicroRNAs/análise , Pirenos/química , Células A549 , Técnicas Biossensoriais/métodos , Química Encefálica , DNA/genética , Ouro/química , Humanos , Limite de Detecção , Nanopartículas Metálicas/química , MicroRNAs/genética , Hibridização de Ácido Nucleico , Oligodesoxirribonucleotídeos/química , Oligodesoxirribonucleotídeos/genética , Técnicas de Microbalança de Cristal de Quartzo/métodos
15.
ACS Sens ; 4(11): 3023-3033, 2019 11 22.
Artigo em Inglês | MEDLINE | ID: mdl-31631654

RESUMO

The extensive use of gold in sensing, diagnostics, and electronics has led to major concerns in solid waste management since gold and other heavy metals are nonbiodegradable and can easily accumulate in the environment. Moreover, gold ions are extremely reactive and potentially harmful for humans. Thus, there is an urgent need to develop reliable methodologies to detect and possibly neutralize ionic gold in aqueous solutions and industrial wastes. In this work, by using complementary measurement techniques such as quartz crystal microbalance (QCM), atomic force microscopy, crystal violet staining, and optical microscopy, we investigate a promising biologically induced gold biomineralization process accomplished by biofilms of bacterium Delftia acidovorans. When stressed by Au3+ ions, D. acidovorans is able to neutralize toxic soluble gold by excreting a nonribosomal peptide, which forms extracellular gold nanonuggets via complexation with metal ions. Specifically, QCM, a surface-sensitive transducer, is employed to quantify the production of these gold complexes directly on the D. acidovorans biofilm in real time. Detailed kinetics obtained by QCM captures the condition for maximized biomineralization yield and offers new insights underlying the biomineralization process. To the best of our knowledge, this is the first study providing an extensive characterization of the gold biomineralization process by a model bacterial biofilm. We also demonstrate QCM as a cheap, user-friendly sensing platform and alternative to standard analytical techniques for studies requiring high-resolution quantitative details, which offers promising opportunities in heavy-metal sensing, gold recovery, and industrial waste treatment.


Assuntos
Biofilmes , Biomineralização/fisiologia , Delftia acidovorans/metabolismo , Ouro/análise , Nanopartículas Metálicas/análise , Benzidinas/química , Corantes/química , Delftia acidovorans/fisiologia , Violeta Genciana/química , Ouro/química , Ouro/metabolismo , Cinética , Nanopartículas Metálicas/química , Oxirredução , Técnicas de Microbalança de Cristal de Quartzo , Coloração e Rotulagem
16.
ACS Appl Mater Interfaces ; 11(44): 41750-41757, 2019 Nov 06.
Artigo em Inglês | MEDLINE | ID: mdl-31603306

RESUMO

Regeneration of antifouling polymer surfaces after contamination or damage is an important issue, especially in complex marine environments. Here, inspired by the self-renewal of silyl acrylate polymers and the protein resistance of zwitterionic polymers, we prepared a novel hydrolysis-induced zwitterionic monomer, tertiary carboxybetaine triisopropylsilyl ester ethyl acrylate (TCBSA), and copolymerized it with methyl methacrylate (MMA). Such a copolymer rapidly self-generates a zwitterionic surface and provides fouling resistance in marine environments. Furthermore, TCBSA was copolymerized with MMA and 2-methylene-1,3-dioxepane (MDO), where MDO causes degradation of the polymers. Our study demonstrates that the degradation of the polymer is controlled, and the degradation rate increases with the external enzyme concentration in the seawater, leading to a self-renewing dynamic surface. Quartz crystal microbalance with dissipation measurements show that the polymeric coating with self-generating zwitterions has excellent protein resistance in seawater. Bioassays demonstrate that the coating can effectively inhibit the adhesion of marine bacteria (Pseudomonas sp.) and diatoms (Navicula incerta). The coating with a self-generating and self-renewing zwitterionic surface is potential to find applications in marine anti-biofouling.


Assuntos
Incrustação Biológica/prevenção & controle , Polímeros/química , Aderência Bacteriana/efeitos dos fármacos , Materiais Revestidos Biocompatíveis/química , Materiais Revestidos Biocompatíveis/farmacologia , Diatomáceas/fisiologia , Metilmetacrilato/química , Polímeros/farmacologia , Pseudomonas/fisiologia , Técnicas de Microbalança de Cristal de Quartzo , Propriedades de Superfície
17.
Int J Nanomedicine ; 14: 7399-7417, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31571858

RESUMO

Purpose: We studied the effects of silver nanoparticles (AgNPs) on human blood platelet function. We hypothesized that AgNPs, a known antimicrobial agent, can be used as blood-compatible, "ideal material'' in medical devices or as a drug delivery system. Therefore, the aim of the current study was to investigate if functionalized AgNPs affect platelet function and platelets as well as endothelial cell viability in vitro. Methods: AgNPs, functionalized with reduced glutathione (GSH), polyethylene glycol (PEG) and lipoic acid (LA) were synthesized. Quartz crystal microbalance with dissipation was used to measure the effect of AgNPs on platelet aggregation. Platelet aggregation was measured by changes in frequency and dissipation, and the presence of platelets on the sensor surface was confirmed and imaged by phase contrast microscopy. Flow cytometry was used to detect surface abundance of platelet receptors. Lactate dehydrogenase test was used to assess the potential cytotoxicity of AgNPs on human blood platelets, endothelial cells, and fibroblasts. Commercially available ELISA tests were used to measure the levels of thromboxane B2 and metalloproteinases (MMP-1, MMP-2) released by platelets as markers of platelet activation. Results: 2 nm AgNPs-GSH, 3.7 nm AgNPs-PEG both at 50 and 100 µg/mL, and 2.5 nm AgNPs-LA at 100 µg/mL reduced platelet aggregation, inhibited collagen-mediated increase in total P-selectin and GPIIb/IIIa, TXB2 formation, MMP-1, and MMP-2 release. The tested AgNPs concentrations were not cytotoxic as they did not affect, platelet, endothelial cell, or fibroblast viability. Conclusion: All tested functionalized AgNPs inhibited platelet aggregation at nontoxic concentrations. Therefore, functionalized AgNPs can be used as an antiplatelet agent or in design and manufacturing of blood-facing medical devices, such as vascular grafts, stents, heart valves, and catheters.


Assuntos
Plaquetas/efeitos dos fármacos , Nanopartículas Metálicas/química , Agregação Plaquetária/efeitos dos fármacos , Prata/farmacologia , Colágeno/metabolismo , Fibroblastos/efeitos dos fármacos , Citometria de Fluxo , Células Endoteliais da Veia Umbilical Humana/efeitos dos fármacos , Células Endoteliais da Veia Umbilical Humana/metabolismo , Humanos , L-Lactato Desidrogenase/metabolismo , Ligantes , Metaloproteinases da Matriz/metabolismo , Nanopartículas Metálicas/ultraestrutura , Selectina-P/metabolismo , Tamanho da Partícula , Complexo Glicoproteico GPIIb-IIIa de Plaquetas/metabolismo , Polietilenoglicóis/química , Técnicas de Microbalança de Cristal de Quartzo , Espectroscopia de Infravermelho com Transformada de Fourier , Tromboxano B2/metabolismo
18.
Colloids Surf B Biointerfaces ; 183: 110442, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31472390

RESUMO

Gangliosides are glycolipids that are enriched on the outer surface of cell membranes. Gangliosides are receptors for a number of signaling molecules and toxins, and therefore are often incorporated into biosensors. Many of these biosensors incorporate gangliosides into supported lipid bilayers which are formed by the spontaneous rupture of unilamellar vesicles on glass or SiO2 substrates. In this work, we used quartz crystal microbalance with dissipation monitoring (QCM-D) to investigate how the presence of the four major brain gangliosides (GM1, GD1a, GD1b, and GT1b) influences the process of supported lipid bilayer formation on SiO2 surfaces. We show that the rate of supported bilayer formation is dependent on both the charge and position of sialic acid moieties on ganglioside molecules. Additionally, Ca2+ can accelerate ganglioside-rich supported bilayer formation, but the degree of acceleration differs for vesicles containing different gangliosides. Fluorescence recovery after photobleaching measurements show that the presence of all gangliosides reduces lipid diffusion coefficients in a concentration-dependent manner, and that Ca2+ slows lipid diffusion in membranes with and without gangliosides. Finally, we use ganglioside-rich supported bilayers to measure binding constants for a GD1a-binding antibody that has similar properties to antibodies present in a variant of Guillain-Barré syndrome.


Assuntos
Encéfalo/metabolismo , Gangliosídeos/metabolismo , Glicolipídeos/metabolismo , Bicamadas Lipídicas/metabolismo , Dióxido de Silício/metabolismo , Lipossomas Unilamelares/metabolismo , Animais , Gangliosídeos/química , Glicolipídeos/química , Bicamadas Lipídicas/química , Lipídeos de Membrana/química , Lipídeos de Membrana/metabolismo , Ácido N-Acetilneuramínico/química , Ácido N-Acetilneuramínico/metabolismo , Técnicas de Microbalança de Cristal de Quartzo/métodos , Ovinos , Dióxido de Silício/química , Lipossomas Unilamelares/química
19.
Biosens Bioelectron ; 145: 111698, 2019 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-31539652

RESUMO

Mycobacterium leprae causes endemic disease leprosy which becomes chronic if not treated timely. To expedite this 'timely diagnosis', and that also at an early stage, here an attempt is made to fabricate an epitope-imprinted sensor. A molecularly imprinted polymer nanoparticles modified electrochemical quartz crystal microbalance sensor was developed for sensing of Mycobacterium leprae bacteria through its epitope sequence. Multiple monomers, 3-sulphopropyl methacrylate potassium salt, benzyl methacrylate and 4-aminothiophenol were utilized to imprint this bacterial epitope. Imprinted nanoparticles were electropolymerized on gold coated quartz electrode. The sensor was able to show specific binding towards the blood samples of infected patients, even in the presence of 'matrix' and other plasma proteins such as albumin and globulin. Even other peptide sequences, similar to epitope sequences only with two amino acid mismatches were also unable to show any binding. Sensor withstood analytical tests viz. selectivity, specificity, matrix effect, detection limit (0.161 nM), quantification limit (and 0.536 nM), reproducibility (RSD 2.01%). Hence a diagnostic tool for bacterium causing leprosy is successfully fabricated in a facile manner which will broaden the clinical access and efficient population screening can be made feasible.


Assuntos
Técnicas Biossensoriais , Hanseníase/diagnóstico , Mycobacterium leprae/isolamento & purificação , Técnicas de Microbalança de Cristal de Quartzo , Epitopos/química , Epitopos/imunologia , Ouro/química , Humanos , Hanseníase/microbiologia , Impressão Molecular , Mycobacterium leprae/imunologia , Mycobacterium leprae/patogenicidade , Nanopartículas/química , Polímeros/química
20.
Colloids Surf B Biointerfaces ; 183: 110447, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31505390

RESUMO

Conventional cell culture surfaces typically consist of polystyrene, with or without surface modifications created through plasma treatment or protein/peptide coating strategies. Other polymers such as fluorinated ethylene propylene are increasingly being implemented in the design of closed cell culture vessels, for example to facilitate the production of cells for cancer immunotherapy. Cultured cells are sensitive to culture vessel material changes through different mechanisms including cell-surface interactions, which are in turn dependent on the amount, type, and conformation of proteins adsorbed on the surface. Here, we investigate the protein deposition from cell culture medium onto untreated polystyrene and fluoropolymer surfaces using quartz crystal microbalance with dissipation monitoring and atomic force microscopy. Both of these non-polar surfaces showed comparable protein deposition kinetics and resulted in similar mechanical and topographical film properties. At protein concentrations found in typical serum-free media used to culture dendritic cells, two deposition phases can be observed. The protein layers form within the first few minutes of contact with the cell culture medium and likely consist almost exclusively of albumin. It is indicated that initial protein film formation will be completed prior to cell settling and initial cell contact will be established with the secondary protein layer. The structural properties of the protein film surface will strongly depend on the albumin concentration in the medium and presumably be less affected by the chemical composition of the cell culture surface.


Assuntos
Microscopia de Força Atômica/métodos , Poliestirenos/química , Proteínas/química , Técnicas de Microbalança de Cristal de Quartzo/métodos , Adsorção , Animais , Técnicas de Cultura de Células/instrumentação , Técnicas de Cultura de Células/métodos , Células Cultivadas , Polímeros/química , Proteínas/metabolismo , Soroalbumina Bovina/química , Propriedades de Superfície
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