Colorimetric point-of-care detection of cholesterol using chitosan nanofibers

Abstract

Recent developments in biosensor-related research have provided economic and highly sensitive biosensors for numerous biological analytes. Several strategies have evolved for developing a sensitive biosensor for cholesterol detection. In this study, we have developed a point-of-care, chitosan nanofiber-based cholesterol biosensor, involving colorimetric detection of the analyte. Chitosan nanofibers, fabricated using electrospinning, were utilized for immobilizing cholesterol oxidase and peroxidase enzymes. A uniform and bead-free chitosan nanofibers were obtained using chitosan and polyvinyl alcohol (Cs: PVA), at the ratio of 0.7:1 w/w, in a solvent system containing 10%v/v of methanol in 63% acetic acid. The nanofibers were characterized using scanning electron microscopy (SEM), which revealed the formation of smooth fibers, with an average diameter of 60–90 nm. The fabricated nanofibers offered a greater surface area for immobilizing high quantities of enzymes and demonstrated the potential to be developed into a strip-based intervention, based on a simple, visual detection system. A colorimetric detection method was developed using the chromogenic substrate, 3,3́,5,5́-tetramethylbenzidine hydrochloride. Analysis by UV–vis spectrophotometry demonstrated a linear increase in the absorbance, with increasing concentrations of cholesterol. The intensity of color change, as a function of cholesterol concentration was used for developing a color gradient scale for the investigated biosensor.