Bioinspired Plasmonic Glyconanosensors for Onsite Optical Detection of Uropathogenic Escherichia coli in Urine Samples

Urinary tract infections (UTIs) are known to impact the lives of 150 million people each year and largely influence the global index of infection. The high rate of incidence of UTIs results in high rates of morbidity and mortality worldwide. The limitation in currently available techniques for the early diagnosis of UTIs is the main reason behind its severity. To overcome the current limitations in detection, rapid biosensors have been developed. We propose glycan-conjugated gold nanoparticles (AuNPs) for the naked-eye detection of bacteria. Herein, we synthesized AuNPs conjugated with multivalent glycans that showed differential binding with bacteria. FimH lectin of Escherichia coli shows an affinity for mannose, while LecA lectin of Pseudomonas aeruginosa shows affinity for galactose. The affinity of all of the glycan-AuNPs has been demonstrated by using a UV–visible spectrophotometer, colorimetric shift, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM). The limit of detection (LOD) was reported to be 10³ and 10² CFU/mL for hexapod and nonapod glycans, respectively, with a detection time of 30 min. The colorimetric biosensor was further explored by red, green, and blue (RGB) color changes by a mobile-phone application for the onsite detection of uropathogenic E. coli in clinical samples. The current innovation of the study is the synthesis of multivalent carbohydrates, which significantly lowers the LOD to 10² CFU/mL and provides a low-cost sensor. Our findings enhanced mobile-phone-based point-of-care testing (POCT) diagnostics in clinical settings, enabling healthcare professionals and nonexperts to make rapid and accurate decisions.