Quantitative determination of biological molecules is a medical procedure performed to detect, diagnose, and monitor diseases. One important example is quantitative estimation of protein human serum albumin (HSA) in body fluids, such as urine, saliva, and plasma. Serum albumin is the most abundant protein in blood plasma. It plays vital roles in maintaining oncotic pressure of blood and serves as a carrier for fatty acids, vitamins, hormones, drugs, etc. Amount of HSA higher than 20 mg/mL in urine is an indicator of kidney damage, which is associated with diabetes and cardiovascular disease. Hence, search for efficient HAS detection methods in body fluids has gained extreme importance among researchers and medical scientists. Several methods are currently available and routinely used in medical diagnosis of HSA. But, they are time consuming and more often require well-equipped laboratory instrumentations. Commercially available assays including urine test strip are also used. But, they may underestimate the concentration of HSA in body fluids.<br/>Recently, fluorometric methods based on fluorescence of organic compounds have gained considerable attentions. Fluorescence techniques are easy to perform, cost-effective, and for quantitative analysis only one compound is required. Along this line, this project aims to develop suitable compounds for easy, cost-effective, and selective detection of HSA in biological samples. We have developed two fluorophores in two easy steps. Comparison of their photophysical properties in different experimental conditions provided various structure-optical property relationships of the fluorophores. Fluorophore without polar functional group was non-fluorescent both in water and in presence of HSA. Whereas, initial fluorescence of the second fluorophore with polar functional group was undetectable in water, but addition of human serum albumin greatly enhanced luminescence of the fluorophore which led to detection of nano-molar amount of the protein in synthetic urine samples. Binding assay as well as displacement analysis indicate selective binding of fluorophore into the protein’s II-A subdomain.<br/>Currently, undergraduate students are developing assays to determine the selectivity and performance of the fluorophore in presence of other proteins, common ions, metabolites in urine.  <br/>

Development of near-infrared emitting fluorophores for potential biosensing application

256th National Meeting (2018)

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