Reduction and temperature responsive ion pair self-assembled nanoparticles composed of poly(allylamine) and α-lipoic acid

초록

Stimuli-responsive nanocarriers can reduce nonspecific drug release and instead trigger drug release selectively at specific sites or under particular conditions, thereby minimizing side effects and enhancing therapeutic efficacy. In this study, ion pair self-assembly (IPSAM) was developed using poly(allylamine) (PAA) and alpha-lipoic acid (ALA) through electrostatic interactions between the amino and carboxylic acid groups. The amphiphilic nature of the resulting PAA/ALA ion pairs enabled spontaneous micelle formation in aqueous media. IPSAM(6/4) exhibited the smallest particle size of 94.1 nm, the lowest polydispersity index of 0.155, and the highest zeta potential of 52.06 mV, indicating superior colloidal stability. FT-IR and 1H-NMR analyses confirmed ion pair formation. Temperature-dependent transmittance measurements showed that the upper critical solution temperature (UCST) of IPSAM(6/4) was approximately 30.7 degrees C. Surface tension analysis indicated that the IPSAM exhibited amphiphilic characteristics. Reductive responsiveness was verified by treatment with dithiothreitol (DTT), which cleaved the disulfide bond of ALA, converting it to dihydrolipoic acid (DHLA) and inducing structural destabilization. Release experiments showed enhanced drug release in response to both thermal and reductive stimuli, with maximal release observed at 45 degrees C in the presence of 20 mM DTT. These results suggest that PAA/ALA IPSAM functions as stimuli-responsive nanocarriers and demonstrate potential for targeted drug delivery in reductive and high-temperature environments such as the tumor microenvironment.Graphical AbstractSchematic representation of reduction and temperature responsive IPSAM formed from poly(allylamine) and alpha-lipoic acid

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