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ACS Biomater Sci Eng ; 10(6): 4018-4034, 2024 06 10.
Artigo em Inglês | MEDLINE | ID: mdl-38816970

RESUMO

Fabrication of label-free immunosensors is highly necessitated due to their simplicity, cost-effectiveness, and robustness. Herein, we report the facile development of a label-free, direct, rapid, capacitive immunosensor for ultrasensitive and rapid recognition of trace levels of Escherichia coli from contaminated food samples. This was achieved using gold platinum core-shell nanoparticles loaded with graphene quantum dots (AuPt@GQDs) that were utilized as electrode modifiers. The incorporation of GQDs to the surface of AuPt core-shell nanoparticles was performed using the "greener" probe-sonication method. The electrochemical properties of AuPt@GQDs, determined using cyclic voltammetry and electrochemical impedance spectroscopy, suggested the optimized loading concentration of AuPt to be 0.05% in the core-shell nanocomposite to exhibit the highest current response. Furthermore, immobilization of anti-E. coli monoclonal antibodies (anti-E. coli mAb) onto the surface of modified electrodes was performed using amine coupling. The high specific binding of E. coli cells onto the surface of the immuno-electrode was measured as a direct function of change in transient capacitance with time that was measured at low and high frequencies. The resultant immunosensor (bovine serum albumin/anti-E. coli mAb/AuPt0.05@GQDs/FTO) demonstrated a detection range (5 to 4.5 × 103 cells/mL), with the detection limit as low as 1.5 × 102 cells/mL, and an excellent sensitivity ∼171,281.40 µF-1 mL cells-1 cm-2 without the use of any labels (R2-0.99). These findings were further verified using real sample analysis wherein the immuno-electrode demonstrated outstanding sensitivity, the highest noticed so far. More interestingly, the high resuability ∼48 weeks (RSD-5.92%) and excellent reproducibility in detection results (RSD ∼ 9.5%) testify its potential use in a clinical setting. The results reveal the usefulness of the surface-engineered AuPt@GQDs core-shell nanocomposite as an electrode modifier that can be used for the development of newer on-site monitoring devices to estimate trace levels of pathogens present as contaminants in food samples.


Assuntos
Técnicas Biossensoriais , Escherichia coli , Contaminação de Alimentos , Ouro , Grafite , Nanocompostos , Platina , Pontos Quânticos , Escherichia coli/isolamento & purificação , Escherichia coli/imunologia , Nanocompostos/química , Grafite/química , Platina/química , Técnicas Biossensoriais/métodos , Contaminação de Alimentos/análise , Pontos Quânticos/química , Ouro/química , Imunoensaio/métodos , Técnicas Eletroquímicas/métodos , Eletrodos , Limite de Detecção , Microbiologia de Alimentos/métodos , Nanopartículas Metálicas/química , Animais
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