A bioconjugated design for amino acid-modified mesoporous silicas as effective adsorbents for toxic chemicals

A general synthetic method for functionalization of mesoporous silica with amino acid has been developed. The carboxylic acid functionalized SBA-15 was conjugated with l-phenylalanine (Phe) and l-tryptophan (Trp) to obtain nontoxic amino acid-conjugated functionalized mesoporous silica materials. The materials were used as adsorbents for the removal of the herbicide Paraquat (PQ) and its analog, ethyl viologen dibromide (EVB) from aqueous solutions. In comparison to the commercially available activated carbon adsorbents, the silica-based adsorbents prepared in this study exhibited relatively higher PQ removal efficiency in aqueous solutions at room temperature and pH 7.0. The silica-based adsorbents, pendant with amino acid moieties exhibited greater adsorption capacities toward PQ and EVB than the analogs but without the amino acid moiety, suggesting that there is a benefit for the enhanced π-π interaction between the aromatic groups of the conjugated amino acid moieties and the adsorbate. This bioconjugated method developed here provides a promising new tool to synthesize new materials for detoxification of herbicides in clinical trials.