Abstract

In this work, a quantitative paper-based sensor integrated with smartphone-application was developed using poly(sodium 4-styrenesulfonate) stabilized copper nanoclusters (PSS-CuNCs) as a fluorescence probe to detect creatinine (CRN). The surface morphology and optical properties of PSS-CuNCs were verified using UV-vis absorption, zeta-potential, photoluminescence, high resolution transmission electron microscopy (HR-TEM) and Fourier-transform infrared (FI-IR) and X-ray photoelectron (XPS) spectroscopy. PSS-CuNCs exhibited strong red fluorescence with the emission peak centered at 654 nm upon excitation at 390 nm. PSS-CuNCs was also used to determine CRN because of their excellent fluorescence properties. The fluorescence of PSS-CuNCs was quenched significantly by adding different concentrations of CRN, which mainly originated from the formation of ground state complexation. The PSS-CuNCs probe showed high sensitivity with a low limit of detection (LOD) of 2.48 nM and high selectivity even in the presence of other interfering analytes. This assay was also used to measure CRN in real samples. Additionally, test paper-based assay has been developed to detect CRN using smartphones. The developed assay provides a reliable, cost-effective, sensitive and portable on-site method to measure CRN levels by utilizing fluorescence color changes. Incorporation of PSS-CuNCs into poly(vinyl alcohol) resulted in the formation of fluorescent transparent polymer thin films with high photostability.