Facile synthesis of nano-sized agarose based amino acid-Its pH-dependent protein-like behavior and interactions with bovine serum albumin.

ABSTRACT

In a facile synthesis agarose was amphoterically functionalized to afford nano-sized agarose amino acids, aminoagarose succinate half-esters (AAE) containing one pendant carboxyl group. Nano-sized AAEs (<10 nm; DLS) were characterized and they had three various degrees of substitution [overall DSs 0.88, 0.89 and 0.96], both the amino and half-ester groups were placed on C-6 positions of the 1,3 beta-d-galactopyranose moieties of agarose backbone ((13)C NMR). AAEs performed like large protein molecules exhibiting pH-responsive structural variations (optical rotatory dispersion), presenting a mixed solubility pattern like random coil (soluble) and aggregate (precipitation) formations. Circular dichroism studies showed their pH-dependent associative interactions with bovine serum albumin, which indicated complexation at acidic and basic pHs, and decomplexation at pH 6.8 with AAE (DS 0.96). Thus, these nano-sized AAE based systems may be of potential utility in the domains demanding the merits of preferential protein bindings e.g. pH-responsive cationic/anionic drug carrier, separations or chiral sensing applications.