POS8-1421
Charge-Reversing Poly(L-alanine-co-L-choline glutamate) Thermogel for Sustained Drug Delivery
Topic
S8. Frontiers of Functional Polymers in Biology and Medicine
When and Where
Oct 1, 2026
08:30 - 09:30
Room 301 (Grand Ballroom)
Session Chairs
Jinkee HONG
Ki Su KIM
Presenter(s)
Rama Moorthy Appa (Ewha Womans University)
Co-Author(s)
Abstract
Poly(L-alanine-co-L-glutamic acid) (PAE) was synthesized by the ring-opening copolymerization of the N-carboxyanhydrides (NCAs) of L-alanine and γ-benzyl-L-glutamate. Following the removal of the benzyl protecting groups, choline was conjugated to PAE to yield the charge-reversible copolypeptide, Poly(L-alanine-co-L-choline glutamate) (PACE). Aqueous solutions of PACE exhibited thermally induced sol-to-gel transition over a polymer concentration range of 8.0–12.0 wt%, with gelation temperatures between 20 and 30 °C.
1H NMR, circular dichroism (CD), and Fourier transform infrared (FTIR) spectroscopic analyses revealed temperature-dependent changes in the secondary structure of the polypeptide and polymer–water interactions, providing molecular insight into the mechanism of thermogelation. The viscoelastic properties during the sol-to-gel transition were further investigated by dynamic rheological measurements as functions of both temperature and shear rate.
A distinctive feature of PACE is its charge-reversal behavior during hydrolytic degradation. Initially, the cationic choline moieties promote electrostatic interactions with negatively charged therapeutic agents, thereby suppressing the initial burst release commonly observed for hydrophilic charged drugs. The degradation process and accompanying charge reversal were monitored by gel permeation chromatography (GPC), 1H NMR spectroscopy, and zeta-potential measurements. The incorporation of charge-reversal functionality into thermogelling polypeptides represents a promising strategy for overcoming the long-standing challenge of burst release associated with conventional thermogelling systems for hydrophilic ionic therapeutics. This presentation will discuss the molecular mechanism of thermogelation together with the charge-reversal-mediated release behavior of a representative anionic drug.
1H NMR, circular dichroism (CD), and Fourier transform infrared (FTIR) spectroscopic analyses revealed temperature-dependent changes in the secondary structure of the polypeptide and polymer–water interactions, providing molecular insight into the mechanism of thermogelation. The viscoelastic properties during the sol-to-gel transition were further investigated by dynamic rheological measurements as functions of both temperature and shear rate.
A distinctive feature of PACE is its charge-reversal behavior during hydrolytic degradation. Initially, the cationic choline moieties promote electrostatic interactions with negatively charged therapeutic agents, thereby suppressing the initial burst release commonly observed for hydrophilic charged drugs. The degradation process and accompanying charge reversal were monitored by gel permeation chromatography (GPC), 1H NMR spectroscopy, and zeta-potential measurements. The incorporation of charge-reversal functionality into thermogelling polypeptides represents a promising strategy for overcoming the long-standing challenge of burst release associated with conventional thermogelling systems for hydrophilic ionic therapeutics. This presentation will discuss the molecular mechanism of thermogelation together with the charge-reversal-mediated release behavior of a representative anionic drug.
