RESUMO
Disposable syringes were used in a novel point-of-care visual test for detecting pathogenic bacteria (Escherichia coli O157:H7 and Salmonella typhimurium). Hybrid nanoflowers composed of platinum nanoparticles and concanavalin A (Pt-nanoflowers) were prepared through a one-pot reaction and were found to be viable catalase mimics. They catalyze the decomposition of hydrogen peroxide (H2O2) to generate O2. When used as labels in immunoassays, they integrate both the functions of biological recognition and signal amplification. The disposable syringe pressure readout was combined with Pt-nanoflower signal conversion and successfully applied to a visual bacteria detection scheme. Both Escherichia coli O157:H7 and Salmonella typhimurium can be quantified with detection limits of as low as 15 and 7 CFU·mL-1, respectively. Graphical abstract One-pot synthetic platinum nanoparticle (PtNP)-concanavalin A hybrid nanoflowers (Pt-nanoflowers), have been used as ideal signal labels for immunoassays and integrating both essential functions of biological recognition and signal amplification. Disposable syringes were used as a readout to detect pathogenic bacteria.
Assuntos
Escherichia coli O157/isolamento & purificação , Peróxido de Hidrogênio/química , Imunoensaio/métodos , Nanopartículas Metálicas/química , Salmonella typhimurium/isolamento & purificação , Seringas , Animais , Anticorpos/imunologia , Concanavalina A/química , Escherichia coli O157/química , Escherichia coli O157/imunologia , Microbiologia de Alimentos/instrumentação , Microbiologia de Alimentos/métodos , Imunoensaio/instrumentação , Limite de Detecção , Leite/microbiologia , Platina/química , Pressão , Salmonella typhimurium/química , Salmonella typhimurium/imunologiaRESUMO
Rapid, sensitive and point-of-care detection of foodborne pathogenic bacteria is essential for food safety. In this study, we found that hemin-concanavalin A hybrid nanoflowers (HCH nanoflowers), as solid mimic peroxidase, could catalyze oxidation of 2,2'-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) diammonium salt (ABTS) in the presence of H2O2 to a green-colored product. HCH nanoflowers, integrating the essential functions of both biological recognition and signal amplification, meet the requirements of signal labels for colorimetric immunoassay of bacteria. In view of the excellent peroxidase mimetic catalytic activity of HCH nanoflowers, a colorimetric biosensing platform was newly constructed and applied for sensitive detection of foodborne Escherichia coli O157:H7 (E. coli O157:H7). The corresponding detection limits was as low as 4.1â¯CFU/mL with wide linear ranges (101-106â¯CFU/mL).