title: Indicator-Impregnated Agarose Films for Colorimetric Measurement of pH.
abstract: In this article, we report on the development of indicator-impregnated agarose sensor films for colorimetric estimation of the pH of different standard buffer solutions and urine samples. In contrast to the conventional paper-based dipstick method, the presented method employs dried agarose that was infused with a chemical indicator, which when exposed to the test sample results in an appropriate chromogenic outcome. The color change was then quantified by the smart camera system. The divulged instrument has been calibrated with standard buffers and also tested with clinical urine samples. The systematic study was conducted to characterize the performance of the presented technique, such as interplate variations, time variations, volume variations, and shelf life study of agarose sensor films for the commercial viability of such a technique. The employed method is competent enough to bring a change in the paradigm of dipstick method from being qualitative estimation to quantitative, manual detection to automated, and a subjective approach of diagnosis to an objective one. The technique presented here has potential application in the field of point-of-care diagnostics with high fidelity, multiplexing, and robust quantitative estimation.
authors.affiliation: 1 Department of Instrumentation and Applied Physics, Indian Institute of Science, Bangalore, Karnataka, India.
authors.forename: Abhishek
authors.initials: A
authors.lastname: Pathak
authors.affiliation: 1 Department of Instrumentation and Applied Physics, Indian Institute of Science, Bangalore, Karnataka, India.
authors.forename: Jayant
authors.initials: J
authors.lastname: Borana
authors.affiliation: 1 Department of Instrumentation and Applied Physics, Indian Institute of Science, Bangalore, Karnataka, India.
authors.forename: Jayesh Vasudeva
authors.initials: JV
authors.lastname: Adhikari
authors.affiliation: 1 Department of Instrumentation and Applied Physics, Indian Institute of Science, Bangalore, Karnataka, India.
authors.forename: Sai Siva
authors.initials: SS
authors.lastname: Gorthi
mesh_terms: D003124:Colorimetry / Q000295:instrumentation / Q000379:methods*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007202:Indicators and Reagents / Q000737:chemistry*; D012685:Sepharose / Q000737:chemistry*; D012996:Solutions / Q000737:chemistry; D014556:Urine / Q000737:chemistry
chemical_list: D007202:Indicators and Reagents; D012996:Solutions; D012685:Sepharose
keywords: agarose; chemical indicator; colorimetric assay; pH measurement; point-of-care diagnostics; shelf life