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1.
Sensors (Basel) ; 21(12)2021 Jun 17.
Artigo em Inglês | MEDLINE | ID: mdl-34204556

RESUMO

Monolithic quartz crystal microbalance (MQCM) has recently emerged as a very promising technology suitable for biosensing applications. These devices consist of an array of miniaturized QCM sensors integrated within the same quartz substrate capable of detecting multiple target analytes simultaneously. Their relevant benefits include high throughput, low cost per sensor unit, low sample/reagent consumption and fast sensing response. Despite the great potential of MQCM, unwanted environmental factors (e.g., temperature, humidity, vibrations, or pressure) and perturbations intrinsic to the sensor setup (e.g., mechanical stress exerted by the measurement cell or electronic noise of the characterization system) can affect sensor stability, masking the signal of interest and degrading the limit of detection (LoD). Here, we present a method based on the discrete wavelet transform (DWT) to improve the stability of the resonance frequency and dissipation signals in real time. The method takes advantage of the similarity among the noise patterns of the resonators integrated in an MQCM device to mitigate disturbing factors that impact on sensor response. Performance of the method is validated by studying the adsorption of proteins (neutravidin and biotinylated albumin) under external controlled factors (temperature and pressure/flow rate) that simulate unwanted disturbances.


Assuntos
Técnicas Biossensoriais , Técnicas de Microbalança de Cristal de Quartzo , Adsorção , Quartzo
2.
Artigo em Inglês | MEDLINE | ID: mdl-34066515

RESUMO

Adsorption kinetics of myoglobin on silica was investigated using the quartz crystal microbalance (QCM) and the optical waveguide light-mode spectroscopy (OWLS). Measurements were carried out for the NaCl concentration of 0.01 M and 0.15 M. A quantitative analysis of the kinetic adsorption and desorption runs acquired from QCM allowed to determine the maximum coverage of irreversibly bound myoglobin molecules. At a pH of 3.5-4 this was equal to 0.60 mg m-2 and 1.3 mg m-2 for a NaCl concentration of 0.01 M and 0.15 M, respectively, which agrees with the OWLS measurements. The latter value corresponds to the closely packed monolayer of molecules predicted from the random sequential adsorption approach. The fraction of reversibly bound protein molecules and their biding energy were also determined. It is observed that at larger pHs, the myoglobin adsorption kinetics was much slower. This behavior was attributed to the vanishing net charge that decreased the binding energy of molecules with the substrate. These results can be exploited to develop procedures for preparing myoglobin layers at silica substrates of well-controlled coverage useful for biosensing purposes.


Assuntos
Técnicas de Microbalança de Cristal de Quartzo , Dióxido de Silício , Adsorção , Concentração de Íons de Hidrogênio , Mioglobina , Análise Espectral , Propriedades de Superfície
3.
J Hazard Mater ; 413: 125467, 2021 07 05.
Artigo em Inglês | MEDLINE | ID: mdl-33930975

RESUMO

Developments of enantioselective devices for discriminating bio-enantiomers is of significant importance. Due to the vital role of Cysteine (Cys) in biological processes and the hazardous effect of its D-enantiomer, discriminating Cys enantiomers without auxiliary enzyme is highly wanted. In this work, a pair of UiO-MOF enantiomers (UiO-tart) have been fabricated through post-modification, which could be further fabricated into enantiomeric sensing devices (UiO-tart@Au). By employing the Quartz Crystal Microbalance (QCM) technology, gravimetric discrimination of Cys enantiomers could be achieved. UiO-tart@Au is highly enantioselective, and the afforded enantioselective factor (5.97 ± 0.54) represents the best performance reported ever. In the fabricated device, MOF layer acts as the chiral selector for specific Cys enantiomer, and the reaction between the captured Cys enantiomer and Au results in the mass growth of the system. Solid-phase extraction (SPE) gives an e.e. value of 71.6 ± 3.8%, substantially confirming the chiral-selector role of UiO-tart. DFT calculations indicate that enantiomeric H-bonding effect and greater reaction enthalpy should be the reason. To the best of our knowledge, this work represents the first example of chiral tartaric acid derived MOF sensors for enantioselective discrimination of Cys, suggesting a promising potential of developing chiral MOFs based devices for enhanced enantioselective application.


Assuntos
Cisteína , Técnicas de Microbalança de Cristal de Quartzo , Extração em Fase Sólida , Estereoisomerismo
4.
Food Chem ; 358: 129853, 2021 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-33933970

RESUMO

The interaction between chitooligosaccharides (COS2-6) and bovine serum albumin (BSA) is worthy of investigation, which provides support for improving the physical properties (gelling, foaming, and emulsifying) of food proteins via COS addition and in vivo research on COS bioactivity. Component analysis indicated that COS2 and COS3 were enriched in the COS2-6-BSA precipitate. The fluorescence binding constant (1.73 × 103 M-1), ΔG of isothermal titration calorimetry (-6.7 kJ/mol), and the predicted ΔG of molecular docking (-10 to -5 kJ/mol) confirmed the weak interaction of COS2-6-BSA. Quartz crystal microbalance dissipation and molecular docking indicated that electrostatic and hydrophobic interactions were the main stabilization forces. Molecular docking showed that the predicted ΔG of COS2-6 to BSA decreased with the increasing degree of polymerization. This work clarified the weak and selective interaction between COS2-6 and BSA via various methods, which is useful for the food application of COS.


Assuntos
Quitina/análogos & derivados , Soroalbumina Bovina/química , Calorimetria , Quitina/química , Quitina/metabolismo , Fluorescência , Interações Hidrofóbicas e Hidrofílicas , Simulação de Acoplamento Molecular , Polimerização , Ligação Proteica , Técnicas de Microbalança de Cristal de Quartzo , Soroalbumina Bovina/metabolismo , Espectrofotometria Ultravioleta , Eletricidade Estática
5.
Langmuir ; 37(15): 4562-4570, 2021 04 20.
Artigo em Inglês | MEDLINE | ID: mdl-33834785

RESUMO

The irreversible formation of cholesterol monohydrate crystals within biological membranes is the leading cause of various diseases, including atherosclerosis. Understanding the process of cholesterol crystallization is fundamentally important and could also lead to the development of improved therapeutic strategies. This has driven several studies investigating the effect of the environmental parameters on the induction of cholesterol crystallite growth and the structure of the cholesterol crystallites, while the kinetics and mechanistic aspects of the crystallite formation process within lipid membranes remain poorly understood. Herein, we fabricated cholesterol crystallites within a supported lipid bilayer (SLB) by adsorbing a cholesterol-rich bicellar mixture onto a glass and silica surface and investigated the real-time kinetics of cholesterol crystallite nucleation and growth using epifluorescence microscopy and quartz crystal microbalance with dissipation (QCM-D) monitoring. Microscopic imaging showed the evolution of the morphology of cholesterol crystallites from nanorod- and plate-shaped habits during the initial stage to mostly large, micron-sized three-dimensional (3D) plate-shaped crystallites in the end, which was likened to Ostwald ripening. QCM-D kinetics revealed unique signal responses during the later stage of the growth process, characterized by simultaneous positive frequency shifts, nonmonotonous energy dissipation shifts, and significant overtone dependence. Based on the optically observed changes in crystallite morphology, we discussed the physical background of these unique QCM-D signal responses and the mechanistic aspects of Ostwald ripening in this system. Together, our findings revealed mechanistic details of the cholesterol crystallite growth kinetics, which may be useful in biointerfacial sensing and bioanalytical applications.


Assuntos
Bicamadas Lipídicas , Técnicas de Microbalança de Cristal de Quartzo , Membrana Celular , Colesterol , Cristalização , Quartzo
6.
J Colloid Interface Sci ; 597: 370-382, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33894545

RESUMO

The proton pump transmembrane protein bacteriorhodopsin was successfully incorporated into planar floating lipid bilayers in gel and fluid phases, by applying a detergent-mediated incorporation method. The method was optimized on single supported bilayers by using quartz crystal microbalance, atomic force and fluorescence microscopy techniques. Neutron and X-ray reflectometry were used on both single and floating bilayers with the aim of determining the structure and composition of this membrane-protein system before and after protein reconstitution at sub-nanometer resolution. Lipid bilayer integrity and protein activity were preserved upon the reconstitution process. Reversible structural modifications of the membrane, induced by the bacteriorhodopsin functional activity triggered by visible light, were observed and characterized at the nanoscale.


Assuntos
Bacteriorodopsinas , Bicamadas Lipídicas , Nêutrons , Técnicas de Microbalança de Cristal de Quartzo
7.
Biosensors (Basel) ; 11(5)2021 Apr 27.
Artigo em Inglês | MEDLINE | ID: mdl-33925584

RESUMO

The plant cell mechanics, including turgor pressure and wall mechanical properties, not only determine the growth of plant cells, but also reflect the functional and structural changes of plant cells under biotic and abiotic stresses. However, there are currently no appropriate techniques allowing to monitor the complex mechanical properties of living plant cells non-invasively and continuously. In this work, quartz crystal microbalance with dissipation (QCM-D) monitoring technique with overtones (3-9) was used for the dynamic monitoring of adhesions of living tobacco BY-2 cells onto positively charged N,N-dimethyl-N-propenyl-2-propen-1-aminiumchloride homopolymer (PDADMAC)/SiO2 QCM crystals under different concentrations of mannitol (CM) and the subsequent effects of osmotic stresses. The cell viscoelastic index (CVIn) (CVIn = ΔD⋅n/ΔF) was used to characterize the viscoelastic properties of BY-2 cells under different osmotic conditions. Our results indicated that lower overtones of QCM could detect both the cell wall and cytoskeleton structures allowing the detection of plasmolysis phenomena; whereas higher overtones could only detect the cell wall's mechanical properties. The QCM results were further discussed with the morphological changes of the BY-2 cells by an optical microscopy. The dynamic changes of cell's generated forces or cellular structures of plant cells caused by external stimuli (or stresses) can be traced by non-destructive and dynamic monitoring of cells' viscoelasticity, which provides a new way for the characterization and study of plant cells. QCM-D could map viscoelastic properties of different cellular structures in living cells and could be used as a new tool to test the mechanical properties of plant cells.


Assuntos
Técnicas de Microbalança de Cristal de Quartzo , Tabaco , Adesão Celular , Microscopia , Osmose/fisiologia , Dióxido de Silício , Tabaco/citologia , Viscosidade
8.
Methods Mol Biol ; 2263: 183-197, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33877598

RESUMO

Quartz crystal microbalance with dissipation monitoring (QCM-D) is one of the most widely used techniques for the deposition of lipid layers and provides a useful tool for protein-ligand analysis. By using functionalized lipids, for example, with nitrilotriacetic acid (NTA) or biotin, one can couple a molecule to the surface to investigate ligand interactions. Using lipid layers in this way allows for the analysis of complex binding events such as conformational changes, fibrillation, and hierarchical clustering on the surface, which is difficult to interpret with conventional surface sensor techniques. Deposition of lipids and subsequent molecular interactions are easily monitored using both the frequency and the dissipation, which have distinct features in bilayer formation and make QCM-D the ideal technique to use. Here we describe the formation of biotinylated lipid bilayers using two different types of lipids and the subsequent addition of avidin, which can then be used as a basis for linking biotinylated molecules to the surface. These protocols can be adapted to use other lipid moieties and linking chemistries.


Assuntos
Heparina/metabolismo , Bicamadas Lipídicas/metabolismo , Técnicas de Microbalança de Cristal de Quartzo/métodos , Avidina/química , Fenômenos Biofísicos , Técnicas Biossensoriais , Biotina/química , Bicamadas Lipídicas/química , Ligação Proteica , Ressonância de Plasmônio de Superfície
9.
Biosensors (Basel) ; 11(2)2021 Feb 19.
Artigo em Inglês | MEDLINE | ID: mdl-33669533

RESUMO

This research reports a portable immunochip, based on quartz crystal microbalance (QCM) for label-free, low-cost qualitative detection of zearalenone (ZEN) in food samples. The experimental parameters in the functionalization and working process were evaluated in detail, in order to achieve a high accuracy and sensitivity. Under optimal conditions, the ZEN concentration at an inhibition ratio of 50% and 15% of the proposed QCM immunochip achieved 3.41 µg L-1 and 0.37 µg L-1, respectively. This portable QCM immunochip also exhibited high specificity, no obvious cross-reaction to five structural analogs of ZEN, and showed other mycotoxins. It could finish the whole qualitative measurement within 30 min, showed good stability during the processes of preparation (SD < 5%, n = 9), storage (frequency response >90%, in PBS at 4 °C for 15 days), and application (frequency response >90% after being reused 6 times). The developed QCM immunochip obtained accurate and repeatable recovery results in ZEN analysis in the chosen food samples (corn, wheat flour, soy sauce, and milk), which had a high correlation (R2 = 0.9844) with that achieved by the HPLC-MS/MS method. In short, this work developed a portable, stable, and reproducible QCM immunochip that could be used for rapid, low-cost, and sensitively measurement of ZEN content in real food samples.


Assuntos
Análise de Alimentos , Técnicas de Microbalança de Cristal de Quartzo/métodos , Zearalenona/análise , Técnicas Biossensoriais , Farinha/análise , Imunoensaio , Micotoxinas/análise
10.
Biosensors (Basel) ; 11(3)2021 Feb 26.
Artigo em Inglês | MEDLINE | ID: mdl-33652946

RESUMO

Chymotrypsin is an important proteolytic enzyme in the human digestive system that cleaves milk proteins through the hydrolysis reaction, making it an interesting subject to study the activity of milk proteases. In this work, we compared detection of chymotrypsin by spectrophotometric dynamic light scattering (DLS) and quartz crystal microbalance (QCM) methods and determined the limit of chymotrypsin detection (LOD), 0.15 ± 0.01 nM for spectrophotometric, 0.67 ± 0.05 nM for DLS and 1.40 ± 0.30 nM for QCM methods, respectively. The sensors are relatively cheap and are able to detect chymotrypsin in 3035 min. While the optical detection methods are simple to implement, the QCM method is more robust for sample preparation, and allows detection of chymotrypsin in non-transparent samples. We give an overview on methods and instruments for detection of chymotrypsin and other milk proteases.


Assuntos
Técnicas Biossensoriais , Quimotripsina/análise , Acústica , Humanos , Técnicas de Microbalança de Cristal de Quartzo
11.
Colloids Surf B Biointerfaces ; 202: 111685, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33721805

RESUMO

A mechanistic understanding of the interaction of graphene oxide (GO) with cell membranes is critical for predicting the biological effects of GO following accidental exposure and biomedical applications. We herein used a quartz crystal microbalance with dissipation monitoring (QCM-D) to probe the interaction of GO with model cell membranes modified with anionic lipids or cholesterol under biologically relevant conditions. The attachment efficiency of GO on supported lipid bilayers (SLBs) decreased with increasing anionic lipid content and was unchanged with varying cholesterol content. In addition, the incorporation of anionic lipids to the SLBs rendered the attachment of GO partially reversible upon a decrease in solution ionic strength. These results demonstrate the critical role of lipid bilayer surface charge in controlling GO attachment and release. We also employed the fluorescent dye leakage technique to quantify the role of anionic lipids and cholesterol in vesicle disruption caused by GO. Notably, we observed a linear correlation between the amount of dye leakage from the vesicles and the attachment efficiencies of GO on the SLBs, confirming that membrane disruption is preceded by GO attachment. This study highlights the non-negligible role of lipid bilayer composition in controlling the physicochemical interactions between cell membranes and GO.


Assuntos
Células Artificiais , Nanopartículas , Membrana Celular , Colesterol , Grafite , Bicamadas Lipídicas , Membranas Artificiais , Fosfolipídeos , Técnicas de Microbalança de Cristal de Quartzo
12.
Langmuir ; 37(13): 3897-3902, 2021 04 06.
Artigo em Inglês | MEDLINE | ID: mdl-33761263

RESUMO

When multilayer heterogeneous proteins are adsorbed on substrate surfaces, the effects of the adsorption state of the initially adsorbed proteins may affect subsequent adsorption. In this study, the relationships between the adsorption state of the initially adsorbed proteins and the amount of secondary adsorbed proteins were examined. A carboxylate-terminated self-assembled monolayer was applied to bovine serum albumin (BSA) solutions of different concentrations for 180 min and subsequently applied to phosphate-buffered saline (PBS) for an additional 180 min to remove weakly adsorbed proteins. The amount of adsorbed proteins was measured using a quartz crystal microbalance with dissipation. The obtained BSA adsorption layer was then applied to mucin solution for 60 min. When a 1.7 mg/mL BSA solution was applied to the surface, the amount of adsorbed BSA after 10 min of adsorption and after washing with PBS for 167 min was >5 × 102 ng/cm2, representing the saturation amount of monolayer-adsorbed BSA in a side-on orientation. In contrast, the amount of adsorbed BSA after 10 min adsorption was <5 × 102 ng/cm2 when a BSA solution with a concentration <0.43 mg/mL was used. The velocity of BSA adsorption plateaued at approximately 0.43 mg/mL, suggesting that the orientation of the adsorbed protein was determined by protein treatment concentration immediately after the proteins were adsorbed. Furthermore, the amount of adsorbed mucin on the BSA adsorption layer decreased as initial BSA treatment concentration increased up to 0.43 mg/mL and plateaued at concentrations above 0.43 mg/mL. These results indicated that the orientation of the initially adsorbed protein was preserved for several hours and affected the subsequent adsorption of mucin.


Assuntos
Técnicas de Microbalança de Cristal de Quartzo , Soroalbumina Bovina , Adsorção , Mucinas , Propriedades de Superfície
13.
Talanta ; 228: 122233, 2021 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-33773737

RESUMO

A sensitive and highly reproducible cardiac troponin I (cTnI) immunoassay in human serum is a challenging research goal for researchers studying biosensors because cTnI can undergo proteolysis and various modifications in blood. Furthermore, the reproducible detection of cTnI at very low concentrations is also required for diagnosing acute myocardial infarction. Here, we present sensitive and highly reproducible quartz crystal microbalance (QCM) immunosensors for the detection of cTnI in human serum. The unique features of this study are the use of a pair of capture antibodies that bind to different epitopes of cTnI, and the use of a signal amplification technique that enlarged the size of the titanium dioxide nanoparticles using photocatalytic silver staining. Since QCM measures changes in the resonance frequency due to the changes in mass occurring on the sensor surface, it is possible to quantitatively analyze cTnI based on the enormous increase in mass using a sandwich immunoassay and subsequent signal amplification by silver staining. The detection limit of the cTnI immunoassay in human serum without photocatalytic silver staining was 307 pg/ml, but 18 pg/ml in photocatalytic silver staining-mediated signal amplification. Thus, amplifying the signal increased the sensitivity and reproducibility of the cTnI immunoassay in human serum.


Assuntos
Técnicas Biossensoriais , Nanopartículas , Humanos , Imunoensaio , Técnicas de Microbalança de Cristal de Quartzo , Reprodutibilidade dos Testes , Titânio , Troponina I
14.
Anal Chim Acta ; 1156: 338329, 2021 Apr 29.
Artigo em Inglês | MEDLINE | ID: mdl-33781458

RESUMO

The interaction of biomolecules, such as proteins, with biomaterial surfaces is key to disease diagnostic and therapeutic development applications. There is a significant need for rapid, low-cost, field-serviceable instruments to monitor such interactions, where open-source tools can help to improve the accessibility to disease screening instruments especially in low- and middle-income countries. We have developed and evaluated a low-cost integrated quartz crystal microbalance (QCM) instrument for biomolecular analysis based on an open-source QCM device. The custom QCM instrument was equipped with a custom-made electronically controlled isothermal chamber with a closed-loop control routine. A thermal coefficient of 5.6 ppm/°C was obtained from a series of evaluations of the implemented control. Additionally, a custom-designed data acquisition system and a mathematical processing and analysis tool is implemented. The quartz crystal detection chips used here incorporate gold and reduced graphene oxide (rGO) coated surfaces. We demonstrate the system capability to monitor and record the biomolecular interaction between a typical protein bovine serum albumin (BSA) and these two substrates. This instrument was compared to a commercial QCM, demonstrating good correspondence between the computed mass adsorption density responses using the Sauerbrey model. For both Au and rGO surfaces, the custom QCM significantly outperforms the commercial system in limit of detection, sensitivity and linear range. The instrument presented here has the potential to serve as a ubiquitous bioelectronic tool for point-of-care disease screening and rapid therapeutics development.


Assuntos
Técnicas Biossensoriais , Grafite , Adsorção , Animais , Bovinos , Ouro , Quartzo , Técnicas de Microbalança de Cristal de Quartzo , Propriedades de Superfície
15.
Carbohydr Polym ; 260: 117818, 2021 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-33712162

RESUMO

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is a conducting polymer frequently used with cellulose, to develop advanced electronic materials. To understand the fundamental interactions between cellulose and PEDOT:PSS, a quartz crystal microbalance with dissipation (QCM-D) was used to study the adsorption of PEDOT:PSS onto model films of cellulose-nanofibrils (CNFs) and regenerated cellulose. The results show that PEDOT:PSS adsorbs spontaneously onto anionically charged cellulose wherein the adsorbed amount can be tuned by altering solution parameters such as pH, ionic strength and counterion to the charges on the CNF. Temperature-dependent QCM-D studies indicate that an entropy gain is the driving force for adsorption, as the adsorbed amount of PEDOT:PSS increased with increasing temperature. Colloidal probe AFM, in accordance with QCM-D results, also showed an increased adhesion between cellulose and PEDOT:PSS at low pH. AFM images show bead-like PEDOT:PSS particles on CNF surfaces, while no such organization was observed on the regenerated cellulose surfaces. This work provides insight into the interaction of PEDOT:PSS/cellulose that will aid in the design of sustainable electronic devices.


Assuntos
Celulose/química , Poliestirenos/química , Tiofenos/química , Adsorção , Concentração de Íons de Hidrogênio , Microscopia de Força Atômica , Nanofibras/química , Concentração Osmolar , Técnicas de Microbalança de Cristal de Quartzo , Propriedades de Superfície , Temperatura
16.
Water Res ; 197: 117066, 2021 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-33774463

RESUMO

Interactions of nanoscale plastics with natural organic matter (NOM) and silica surfaces were investigated using a quartz crystal microbalance with dissipation monitoring (QCM-D). Polyethylene and polystyrene are the most used plastic polymers and most likely to accumulate in the environment, and thus their nano-scale interactions were investigated in this study. Deposition and release of polyethylene and polystyrene nanoscale plastics were investigated on silica and NOM-coated surfaces in the presence of different salt types (NaCl, CaCl2, MgCl2) and ionic strengths (IS). Polyethylene nanoscale plastics showed negligible deposition on silica surface, while significant deposition of polystyrene nanoscale plastics was observed on silica surface. However, both polyethylene and polystyrene nanoscale plastics showed significant deposition on NOM-coated surfaces, with polystyrene showing higher deposition. Increased IS resulted in greater deposition of both polyethylene and polystyrene nanoscale plastics on NOM-coated surfaces due to the functional groups, following DLVO theory. Deposited polyethylene nanoscale plastics on NOM-coated surfaces can be remobilized whereas deposition of polystyrene nanoscale plastics was irreversible on both silica and NOM-coated surfaces. Overall, higher deposition of nanoscale plastics on NOM-coated surfaces indicates that fate and mobility of nanoscale plastics in the environment will be significantly governed by their interactions with NOM.


Assuntos
Técnicas de Microbalança de Cristal de Quartzo , Dióxido de Silício , Concentração Osmolar , Plásticos , Quartzo , Propriedades de Superfície
17.
Anal Chem ; 93(8): 4033-4041, 2021 03 02.
Artigo em Inglês | MEDLINE | ID: mdl-33596063

RESUMO

We report artificial nanopores in the form of quartz nanopipettes with ca. 10 nm orifices functionalized with molecular recognition elements termed aptamers that reversibly recognize serotonin with high specificity and selectivity. Nanoscale confinement of ion fluxes, analyte-specific aptamer conformational changes, and related surface charge variations enable serotonin sensing. We demonstrate detection of physiologically relevant serotonin amounts in complex environments such as neurobasal media, in which neurons are cultured in vitro. In addition to sensing in physiologically relevant matrices with high sensitivity (picomolar detection limits), we interrogate the detection mechanism via complementary techniques such as quartz crystal microbalance with dissipation monitoring and electrochemical impedance spectroscopy. Moreover, we provide a novel theoretical model for structure-switching aptamer-modified nanopipette systems that supports experimental findings. Validation of specific and selective small-molecule detection, in parallel with mechanistic investigations, demonstrates the potential of conformationally changing aptamer-modified nanopipettes as rapid, label-free, and translatable nanotools for diverse biological systems.


Assuntos
Aptâmeros de Nucleotídeos , Técnicas Biossensoriais , Nanoporos , Técnicas de Microbalança de Cristal de Quartzo , Serotonina
18.
J Environ Sci Health B ; 56(4): 370-377, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33616003

RESUMO

This study aimed to develop an aptasensor for paraquat detection by gold nanoparticles. The specific aptamer for paraquat was selected by using the SELEX process via capillary electrophoresis. Sixty-three aptamer candidates were amplified by asymmetric PCR and screened for paraquat binding using gold nanoparticles (AuNPs). Aggregation of AuNPs was specifically induced by desorption of paraquat binding aptamers from the surface of AuNPs as a result of aptamer-target interaction leading to the color change from red to purple. Aptamer 77F with the following sequence: 5'-AGGCTTACACCTGAAAAGCGGCTTAATTTACACTACTGTAT-3' was selected as a highly specific aptamer for paraquat. The detection limit of paraquat was 0.267 µg/mL by colorimetry and 1.573 µg/mL by the quartz crystal microbalance (QCM) technique. This aptamer showed specificity for paraquat by colorimetry. Dimethyl phophite, diethyl phophite and O,O diethyl thiophosphate potassium salt did not react by colorimetry but, exhibited a weak nonspecific reaction by QCM. This is first time that an aptasensor was used for detection of paraquat based on QCM. However, the aptasensor based on the colorimetric method simply uses a generation of a signal that can be detected by the naked eye. This technique is rapid, low cost easy to use and suitable for on-site detection of herbicide residue.


Assuntos
Aptâmeros de Nucleotídeos/química , Colorimetria/métodos , Paraquat/análise , Aptâmeros de Nucleotídeos/genética , Aptâmeros de Nucleotídeos/metabolismo , Técnicas Biossensoriais/métodos , Colorimetria/instrumentação , Eletroforese Capilar , Ouro/química , Herbicidas/análise , Limite de Detecção , Nanopartículas Metálicas/química , Paraquat/metabolismo , Reação em Cadeia da Polimerase , Técnicas de Microbalança de Cristal de Quartzo/métodos , Sensibilidade e Especificidade
19.
Langmuir ; 37(7): 2256-2267, 2021 02 23.
Artigo em Inglês | MEDLINE | ID: mdl-33560854

RESUMO

Supported lipid bilayers (SLBs) have proven to be valuable model systems for studying the interactions of proteins, peptides, and nanoparticles with biological membranes. The physicochemical properties (e.g., topography, coating) of the solid substrate may affect the formation and properties of supported phospholipid bilayers, and thus, subsequent interactions with biomolecules or nanoparticles. Here, we examine the influence of support coating (SiO2 vs Si3N4) and topography [sensors with embedded vs protruding gold nanodisks for nanoplasmonic sensing (NPS)] on the formation and subsequent interactions of supported phospholipid bilayers with the model protein cytochrome c and with cationic polymer-wrapped quantum dots using quartz crystal microbalance with dissipation monitoring and NPS techniques. The specific protein and nanoparticle were chosen because they differ in the degree to which they penetrate the bilayer. We find that bilayer formation and subsequent non-penetrative association with cytochrome c were not significantly influenced by substrate composition or topography. In contrast, the interactions of nanoparticles with SLBs depended on the substrate composition. The substrate-dependence of nanoparticle adsorption is attributed to the more negative zeta-potential of the bilayers supported by the silica vs the silicon nitride substrate and to the penetration of the cationic polymer wrapping the nanoparticles into the bilayer. Our results indicate that the degree to which nanoscale analytes interact with SLBs may be influenced by the underlying substrate material.


Assuntos
Bicamadas Lipídicas , Nanopartículas , Membrana Celular , Técnicas de Microbalança de Cristal de Quartzo , Dióxido de Silício
20.
Mater Sci Eng C Mater Biol Appl ; 121: 111813, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33579457

RESUMO

Extracellular vesicles (EVs) are particles originating from the exfoliation of the cellular membrane. They are involved in cell-to-cell and cell-to-matrix signaling, exchange of bioactive molecules, tumorigenesis and metastasis, among others. To mitigate the limited understanding of EVs transfer phenomena, we developed a simplistic model that mimics EVs and their interactions with cells and the extracellular matrix. The proposed model is a layer by layer (LbL) film built from the polycationic poly-l-lysine (PLL) and the glycosaminoglycan hyaluronic acid (HA) to provide ECM mimicry. Positively charged 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and N1,N1,N14,N14-tetramethyl-N1,N14-ditetradecyltetradecane-1,14-diaminium dibromide (GS14) liposomes were embedded in this construct to act as EVs analogs. To simulate EVs carrying substances, Nile Red was loaded as a model of lipophilic cargo molecules. The integration of each component was followed by quartz crystal microbalance measurements, which confirmed the immobilization of intact liposomes on the underlying (PLL/HA)3 soft film. The release of Nile Red from liposomes either embedded in the LbL construct or exposed at its surface revealed a fast first order release. This system was validated as a model for EV/cell interactions by incubation with breast cancer cells MDA-MB-231. We observed higher internalization for embedded liposomes when compared with surface-exposed ones, showcasing that the ECM mimic layers do not constitute a barrier to liposome/cell interactions but favor them.


Assuntos
Vesículas Extracelulares , Lipossomos , Ácido Hialurônico , Técnicas de Microbalança de Cristal de Quartzo
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