Flower-based sustainable paper analytical sensor for the detection of copper ions and antimicrobial performance

Day-by-day monitoring of the environment is gaining attention, thereby leading to the evolution of sustainable conventional probes as a suitable sensing platform. This work deals with the development of low-cost, multifunctional colorimetric sensing of Cu²⁺ metal ions in the environment with pH monitoring, using Hibiscus rosa-sinensis extract containing anthocyanins that act as an indicator, forming a complex. The UV-visible spectrophotometer shows a reliable anthocyanin content obtained using a water extract. This is further combined with the ratiometric quantitative analysis using smartphone assistance, processed using RGB channels, which acts as a user-friendly portable analytical tool with good reliability. The LOD of detection of Cu²⁺ through the smartphone technique was found to be 1.31x10^-5 M with a feasible linearity of R² = 0.935. The same phytochemical properties were screened against various microbial organisms, such as E. coli, S. aureus, and A. Niger, for resistance. Therefore, this work provides a multifunctional, sustainable platform for point-of-care sensing of Cu²⁺ and its antimicrobial resistance.