Depletion of albumin and immunoglobulin G from human serum using epitope-imprinted polymers as artificial antibodies.

Serum is a readily available source for noninvasive studies in clinical research, but it contains abundant proteins such as albumin and immunoglobulin G that can hinder the presence of low-abundant proteins as well as decrease sample loading capacity of analytical methods. Therefore, depletion of these two proteins is required to observe low-abundance serum proteins. Molecularly imprinted polymers are template-induced artificial antibodies with the ability to recognize and selectively bind the target molecule. In this study, artificial albumin and immunoglobulin G antibodies were developed by using two epitopes of human serum albumin and immunoglobulin G as templates. Acrylic acid, acrylamide, and N-acryl tyramine were the corresponding monomers; N,N'-ethylene bisacrylamide served as a cross-linker, and cellulosic fibers were used as a supporting matrix. The adsorption capacity of these artificial antibodies was 15.2 mg, 10 mg, and 15 μL per gram for human serum albumin, immunoglobulin G, and human serum, respectively. The dissociation constant (Kd ) of these artificial antibodies toward the human serum albumin and immunoglobulin G was 1 μM and 0.6 μM, respectively. The biomimetic properties of these artificial antibodies, coupled with their economical and rapid production, high specificity and their reusability, make them attractive for protein separation and analysis.