Allylamine-Conjugated Polyacrylic Acid and Gold Nanoparticles for Colorimetric Detection of Bacteria

Abstract

The increasing resistance of pathogenic bacteria to the pharmaceutical compound could be a very important issue for public health. A sensitive, fast and accurate approaches for bacteria detection are going to be needed to enhance the effectiveness of treatment. This study aimed to develop a colorimetric sensor based on allylamine-conjugated polyacrylic acid and gold nanoparticles (AuNPs- AAm-PAA) for bacteria detection. Allylamine was conjugated to the polyacrylic acid and mixed with the gold colloid to form a self-assembled AuNPs-AAm-PAA. The polymer-modified gold nanoparticles were characterized for the particle size, zeta potential, reversibility using TEM, particle size analyzer, and UV-Vis spectrophotometer, respectively. The system was observed to detect bacteria and observed by the naked eye, UV-Vis spectrophotometer, and TEM. The results showed that AuNPs-PAA-AAm solution showed an absorbance peak at 530 nm, AuNPs particle size of 25.67 nm ± 2.68, and zeta potential -31.4 ± 4.5 mV. Introduction of bacteria into the Au-AAm-PAA solution resulted in a color change from red to purple at concentrations of 6x108 CFU/mL of Staphylococcus aureus and Escherichia coli. TEM analysis revealed the binding of aggregated gold nanoparticles around the outer membrane of bacteria. The sensor system based on conjugated polymer and gold nanoparticles demonstrated a promising way for bacteria detection.