RESUMO
Staphylococcus aureus is an important pathogen that causes nosocomial infections, resulting in unacceptable morbidity and mortality rates. In this work, we proposed the construction of a nanostructured ZnO-based electrochemical immunosensor for qualitative and semiquantitative detection of S. aureus using simple methods for growing zinc oxide nanorods (ZnO NRs) on a sensor board and immobilizing the anti-S. aureus antibody on ZnO NRs through cystamine and glutaraldehyde. The immunosensor detected S. aureus in the 103-107 colony-forming unit (CFU) mL-1 range and showed a limit of detection (LoD) around 0.792 × 103 CFU mL-1. Beyond a satisfactory LoD, the developed immunosensor presented other advantages, such as high versatility for point-of-care assays and a suitable selective factor that admits the detection of the S. aureus concentration range in human hand skin after washing. Moreover, the immunosensor showed the potential to be an excellent device to control nosocomial infection by detecting the presence of S. aureus in human hand skin.
Assuntos
Técnicas Biossensoriais , Infecção Hospitalar , Técnicas Eletroquímicas , Sistemas Automatizados de Assistência Junto ao Leito , Pele , Staphylococcus aureus , Óxido de Zinco , Humanos , Staphylococcus aureus/isolamento & purificação , Infecção Hospitalar/prevenção & controle , Pele/microbiologia , Técnicas Biossensoriais/métodos , Óxido de Zinco/química , Imunoensaio/métodos , Técnicas Eletroquímicas/métodos , Infecções Estafilocócicas/diagnóstico , Infecções Estafilocócicas/microbiologia , Mãos/microbiologia , Limite de Detecção , Nanotubos/química , Anticorpos Imobilizados/químicaRESUMO
Polypyrrole (PPy) is an interesting conducting polymer due to its good environmental stability, high conductivity, and biocompatibility. The association between PPy and metallic nanoparticles has been widely studied since it enhances electrochemical properties. In this context, gold ions are reduced to gold nanoparticles (AuNPs) directly on the polymer surface as PPy can be oxidized to an overoxidized state. This work proposes the PPy electrochemical synthesis followed by the direct reduction of gold on its surface in a fast reaction. The modified electrodes were characterized by electronic microscopic and infrared spectroscopy. The effect of reduction time on the electrochemical properties was evaluated by the electrocatalytic properties of the obtained material from the oxidation of ascorbic acid (AA) and electrochemical impedance spectroscopy studies. The presence of AuNPs improved the AA electrocatalysis by reducing oxidation potential and lowering charge transfer resistance. EIS data were fitted using a transmission line model. The results indicated an increase in the electronic transport of the polymeric film in the presence of AuNPs. However, PPy overoxidation occurs when the AuNPs' deposition is higher than 30 s. In PPy/AuNPs 15 s, smaller and less agglomerated particles were formed with fewer PPy overoxidized, confirming the observed electrocatalytic behavior.
Assuntos
Técnicas Biossensoriais , Nanopartículas Metálicas , Ácido Ascórbico , Técnicas Biossensoriais/métodos , Ouro/química , Íons , Polímeros/química , Pirróis/químicaRESUMO
An amendment to this paper has been published and can be accessed via a link at the top of the paper.
RESUMO
In this work, we report a develop of electrochemical immunosensor based on ZnO nanostructures immobilized with ZIKV-NS1 antibody on Printed Circuit Board (PCB). ZnO nanostructures were grown on PCB by chemical bath deposition (CDB) and characterized by SEM. ZIKV-NS1 antibody was immobilized on the ZnO nanostructures surface via cystamine and glutaraldehyde. The samples were characterized by Immunofluorescence Confocal Microscopy and FTIR to identify the immobilization of the antibody to the sensor board. The analytical responses of the immunosensor were evaluated by Cyclic Voltammetry (CV). The biosensor developed here allows rapid detection of Zika virus in undiluted urine, without cross reactive with DENV-NS1 antigen, with linear range 0.1â¯â¯ngâ¯mL-1 to 100â¯ngâ¯mL-1. The limit of detection is lower than 1.00â¯pg⯠mL-1. The biosensor is portable, cost-effectiveness, and simple to use, which makes it ideal for point-of-care applications.
Assuntos
Nanopartículas Metálicas/química , Proteínas não Estruturais Virais/urina , Infecção por Zika virus/diagnóstico , Óxido de Zinco/química , Anticorpos Imobilizados/imunologia , Biomarcadores/análise , Técnicas Biossensoriais/métodos , Diagnóstico Precoce , Técnicas Eletroquímicas/instrumentação , Técnicas Eletroquímicas/métodos , Eletrodos , Humanos , Imunoensaio/métodos , Limite de Detecção , Nanotubos/química , Proteínas não Estruturais Virais/imunologia , Zika virus/químicaRESUMO
This work discusses the parameters and characteristics required on the development of a scalable and reliable electrochemical sensor board for detecting 8-hydroxy-2'-deoxyguanosine (8-OHdG), an oxidative stress biomarker for diabetic nephropathy, cancer and Parkinson's disease. We used Printed Circuit Board (PCB) technology to make a precise, low-cost bare sensor board. ZnO nanorods (NRs) and ZnO NRs: reduced graphene oxide (RGO) composites were used as a pathway for antibody immobilization on the working electrode (WE). The parameters and characteristics of the WE were controlled for enhancing the quality of the electrochemical sensor board. Thickness of the gold and the presence of ZnO NRs or their composite on the WE have influence on charge transference process and reproducibility of the sensor board. The amount of the antibody, and its incubation period are crucial to avoid saturation of the sites during immobilization step and reduce the cost of the sensor. Our ZnO NRs-based electrochemical sensor board showed high sensitivity and selectivity to 8-OHdG with detection capacity in the range of 0.001-5.00 ng.mL-1. The successful application of our immunosensor to detect 8-OHdG in urine was evidenced.
Assuntos
8-Hidroxi-2'-Desoxiguanosina/urina , Técnicas Biossensoriais/métodos , Técnicas Eletroquímicas/métodos , Anticorpos Imobilizados , Biomarcadores/urina , Calibragem , Humanos , Microscopia de Fluorescência , Nanotubos/ultraestrutura , Óxido de ZincoRESUMO
In this research, ZnO nanorods - Au nanoparticles nanohybrids have been fabricated and employed to sensitive electrochemical strategy for the specific detection of the ovarian cancer antigen CA-125/MUC126. The microdevice was developed in our lab based on gold and silver electrodes sputtered on glass substrate. The ZnO nanorods arrays were grown on working electrode using assisted microwave hydrothermal synthesis than gold nanoparticles (Au NPs) were deposited by sputtering. The Au NPs onto ZnO nanorods surface provides a favorable platform for efficient loading of anti-CA-125 antibody via binding with cystamine and glutaraldehyde. The effective loading of the biological material (CA-125 antibody and antigen) on the matrix was observed by SEM images. The electrochemical immunosensor shows a sensitive response to ovarian cancer antigen recombinant human CA-125/MUC126 with detection of 2.5ng/µL, 100 times lower than immunoblot system. Due to high specificity, reproducibility and noteworthy stability, the developed sensor will provide a sensitive, selective and convenient approach to be used to detect CA-125/MUC126.
Assuntos
Nanopartículas Metálicas , Nanotubos , Técnicas Biossensoriais , Antígeno Ca-125 , Técnicas Eletroquímicas , Feminino , Ouro , Humanos , Imunoensaio , Neoplasias Ovarianas , Reprodutibilidade dos TestesRESUMO
In this report, hierarchical ZnO nano- and microstructures were directly grown for the first time on a bacterial cellulose substrate and on two additional different papers by hydrothermal synthesis without any surface modification layer. Compactness and smoothness of the substrates are two important parameters that allow the growth of oriented structures.