Rapid colorimetric detection of proteins and bacteria using silver reduction/precipitation catalyzed by gold nanoparticles

Abstract

A colorimetric immunoassay has been developed based on the reduction and precipitation of silver ions catalyzed by colloidal gold. This method was evaluated for a noncompetitive heterogeneous immunoassay to detect ovalbumin as a model protein and Escherichia coli as model bacterium. The influence of relevant experimental variables, including the reaction time of antigen with antibody, the dilution ratio of the colloidal gold-labeled protein, time allowed for silver reduction/precipitation reaction and other parameters were examined and optimized. This colorimetric method of detection is convenient, easy to use and economic. The presence of the target molecules or antigens can be visually inferred based on the color change that occurs in a short time without using major instrumentation. This method is widely amenable for detection of proteins, viruses and bacteria.

Development of nanoparticle-based optical sensors for pathogenic bacterial detection

“…In another study, pathogenic bacteria were detected using antibody-conjugated magnetic nanoparticles [ 87 ]. Following synthesis, nanoparticles were magnetically separated from the analyte and used to detect Salmonella in milk.…”

Specific Colorimetric Detection of Proteins Using Bidentate Aptamer‐Conjugated Polydiacetylene (PDA) Liposomes

“…Point‐of‐care (POC) diagnostics hold the promise to play a pivotal role in public health by significantly decreasing the time between diagnosis and treatment 1. Among the many approaches that have been developed, colorimetric biosensors possess an inherent advantage in that they do not require any instrumentation or power supply, making them ideal for low‐resource settings 2–12. Previously, colorimetric protein detection has been achieved by methods such as the enzyme‐linked immunosorbent assay (ELISA),2 colorimetric metal nanoparticles (e.g., silver3 and gold4), bio‐barcode amplification (BCA),5 and the colorimetric immuno‐protein phosphatase inhibition assay (CIPPIA) 6.…”

“…Among the many approaches that have been developed, colorimetric biosensors possess an inherent advantage in that they do not require any instrumentation or power supply, making them ideal for low‐resource settings 2–12. Previously, colorimetric protein detection has been achieved by methods such as the enzyme‐linked immunosorbent assay (ELISA),2 colorimetric metal nanoparticles (e.g., silver3 and gold4), bio‐barcode amplification (BCA),5 and the colorimetric immuno‐protein phosphatase inhibition assay (CIPPIA) 6. Recently, there has been significant interest in using conjugated polymers as biosensors,7–12 because the polymer backbones in such systems can directly function as optical reporters for molecular binding interactions and interfacial biological processes.…”