Bovine serum albumin (BSA) has been recognized as a marker of the cow's health, milk quality, an allergenic protein and as a carrier. Its detection is important in the food, pharmaceutical and medical industries. However, traditional techniques used to detect BSA are often time-consuming, expensive, and show limited sensitivity. This paper describes properties of polydiacetylene-triblock copolymer (L64) nanosensors, synthesized to easily detect BSA. Sensor efficiency was studied as a function of nanosensor composition, polydiacetylene chemical structures, BSA conformation and hydrophobic domain availability, using spectroscopic, calorimetric, light scattering, and electrokinetic analyses. Nanosensors were sensitive to detect the average BSA concentration of milk and dairy products and discriminated between native and denatured protein through naked-eye detectable blue-to-red transition. The standard Gibbs free energy (-10.44<ΔG°<-49.52kJM), stoichiometry complex (1<"n"<3), and binding constant (6.7×102<Ka<4.79×108M-1) of BSA-nanosensor complex formation established a direct relationship between nanosensor response and BSA-nanosensor interaction. BSA-nanosensor interaction was entropically (without cholesterol), and enthalpically driven (with cholesterol). Eugenol-BSA complex did not induce colorimetric transition. Polydiacetylene-L64 nanosensors are potential low-cost sensors for rapid detection of BSA, discriminating between native/denatured and free/bound protein.
Keywords: Fluorescence; Microcalorimetry; Milk protein; Nanosensor; Zeta potential.
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