Self-assembled polymer vesicles in deciding action of Zn-sulfanilamide allergenicity

Allergic reactions to sulfonamide-based drugs are quite common; hence, medications containing sulfonamides are prescribed carefully. Metal ion complexation may block the nitrogen binding site of sulfonamide by complexation and reduce such responses. In this study, trace concentrations of Zn were found to bind with sulfanilamide at pH ∼ 1. The complexation was studied in water as well as in vesicular medium of polyethylene glycol (PEG) and a block copolymer, PPG-PEG-PPG. The binding constants (k) of Zn-sulfanilamide complex were determined in water, PEG, and PPG-PEG-PPG block copolymer media. The values suggest that complexation occurs best in water followed by PPG-PEG-PPG, PEG #4000, and PEG #12000. Though the binding constants are high in water and block copolymer media, the complex is not very stable as the absorbance value for the complex was found to decline with time. The same complex when prepared in polymer matrix shows higher stability. The results prompted us to explore the extraction possibilities of the Zn-sulfanilamide complex by using aqueous biphasic extraction systems comprising the polymers against sodium sulfate solution. The complex was analyzed for its allergenic response in different media by competitive enzyme-linked immunosorbent assay (ELISA) technique. The allergic response of the compounds in the respective media is the resultant of the binding constant and the stability of the complex in that particular medium.