Enhancement of microsphere specificity to purify human serum albumin from blood plasma

Efforts to rapidly and easily supply purified human serum albumin (HSA) in remote areas during a pandemic are challenging. Here, we developed an HSA-imprinted microsphere (HSAIM) as a matrix to purify HSA from blood plasma on a small scale. HSAIMs were generated by encapsulating silica-3-(2-imidazoline-1-yl) propyltriethoxysilane-Cu²⁺-HSA (SiO₂-IMEO-Cu²⁺-HSA) into agarose gel, and the stereospecific template for HSA was obtained by eluting the agarose gel. The physicochemical properties and performance of HSAIM were evaluated, and HSAIMs were applied to purify HSA from human blood plasma. Spherical HSAIMs had an average diameter of 51.2 ± 6.1 μm. HSAIMs had a maximum adsorption of 8.77 × 10^-2 μmol HSA g^-1 with an imprinting factor of 2.83, and the selectivity factors of BSA, thrombin and IgG were 0.96, 0.59 and 0.26, respectively. HSAIMs had a dynamic binding capacity (DBC_10%) of 5.94 × 10^-2 μmol HSA g^-1 and could be reused up to 10 cycles with an ultimate recovery of 55.92%. HSA adsorption kinetics of HSAIM fitted to a pseudo-second-order mechanism, and HSA binding characteristics fit with a Sips isotherm model. For practical purposes, an initial blood plasma sample containing 24.9 ± 2.5 mg protein was pretreated with ethanol yielding 14.5 ± 4.6 mg protein, and further purification with HSAIM yielded 3.6 ± 1.1 mg protein. Starting with a blood plasma sample containing 149 type proteins, a single protein identified as HSA was obtained after final purification step with the HSAIM column, indicating that HSAIMs stereospecifically bound HSA. Hence, HSAIM was promising for blood plasma purification on a small scale.