A rapid colorimetric sensing methodology for urinary tract bacterial pathogens as a point-of-care approach using natural anthocyanin loaded nanosilver

Various commercial diagnostic kits have been used to detect uropathogens. However, non-intensive, sensitive, and instantaneous detection of bacteria in urine is still at its infancy. Herein, a facile attempt was carried out to detect the most common uropathogens using anthocyanin-loaded silver nanoparticles as the indicator. The significance of the current research was to apply the crucial sensing ability of eggplant peel anthocyanin to detect each pathogen by exhibiting discrete colors, based on pH of the urine sample. The novelty of this study was the ability of a single indicator compound to distinctively differentiate multiple uropathogens, as monocultures or consortia, with accurate chromacity, simultaneously and instantaneously. Anthocyanin (AC) from eggplant (Solanum melongena) peels acted as a pH responsive sensor in the prepared indicator solution. The solution was used to sense three each of Gram-positive and Gram-negative uropathogens, as both monoculture and consortium. AC was loaded onto silver nanoparticles (AgNP) to stabilize the pigment. An evident color change due to the function of AC was considered as the end-point of detection. The optimized conditions for the study were obtained as: 50 mu L indicator solution, 10(5) CFU.mL(-1) inoculum, and instantaneous sensing time. Deprotonation and protonation of AC due to ammonia and acids, evolved from the microbes, subsequently varied the pH level in the medium. These resulted in the generation of colors as hues of yellow, orange, green and blue and semi-quantitatively represented using average RGB values and delta E analysis obtained after the indicator solution was added to 24 h bacterial growth. In conclusion, the proposed solution can be a potential alternative to the conventional diagnostic tools as a specific, sensitive, rapid, precise and affordable indicator for point-of-care diagnosis of urinary tract infection.