Natural polysaccharide-based molecularly imprinted polymers as sorbents for selective removal of amino acids as a potential approach for management of aminoacidopathies: Template and monomer selection study.

Phenylketonuria and histidinemia are metabolic conditions characterized by the buildup of certain amino acids resulting from enzymatic deficiencies. Approaches that diminish the intestinal uptake of these amino acids may assist in regulating their systemic concentrations. Molecularly imprinted polymers provide specialized recognition sites that facilitate the precise binding of particular molecules. Natural polymers like chitosan and alginate offer biocompatible frameworks that could improve the efficacy of these systems. Four molecularly imprinted polymers were created utilizing l-phenylalanine as the template and l-phenyllactic acid as a dummy template within chitosan and chitosan/alginate matrices. Characterization employing Fourier-transform infrared spectroscopy and scanning electron microscopy validated the successful imprinting and exhibited clearly defined microcavities, especially with the use of l-phenylalanine and chitosan/alginate polymer. This polymer exhibited an imprinting factor of 2.5 and a substantial binding capacity (15.1 mg/g), nearly double that of the chitosan-only variant (7.6 mg/g), underscoring the notable role of alginate. The polymer adhered to second-order adsorption kinetics, indicating chemical sorption, and Langmuir isotherms, supporting the formation of imprinted cavities. In terms of monomer selection, employing l-phenylalanine as a template demonstrated enhanced selectivity, evidenced by a specificity factor of <1 for alternative amino acids. Nonetheless, the l-phenyllactic acid-imprinted polymer exhibited a strong affinity for certain amino acids such as histidine, threonine, and tryptophan, compromising its selectivity. The evaluation of cytotoxicity validated positive biocompatibility. The results underscore the significant role of ALG in enhancing binding capacity, thereby augmenting the potential of MIPs as selective sorbents for amino acid-related metabolic disorders. This research lays the groundwork for the implementation of therapeutic MIP-based sorbents to enhance the well-being of individuals suffering from aminoacidopathies and other diet-related disorders.