Antimicrobial loading into and release from poly(ethylene glycol)/poly(acrylic acid) semi‐interpenetrating hydrogels. Issue 1 (28th September 2015) - Wu, Yong
ABSTRACT: Electrostatic interactions within a semi‐interpenetrating network (semi‐IPN) gel can control the postsynthesis loading, long‐term retention, and subsequent release of small‐molecule cationic antibiotics. Here, electrostatic charge is introduced into an otherwise neutral gel [poly(ethylene glycol) (PEG)] by physically entrapping high‐molecular‐weight poly(acrylic acid) (PAA). The network structure is characterized by small‐angle neutron scattering. PEG/PAA semi‐IPN gels absorb over 40 times more antibiotic than PAA‐free PEG gels. Subsequent soaking in physiological buffer (pH 7.4; 0.15 M NaCl) releases the loaded antibiotics for periods as long as 30 days. The loaded gels elute antibiotics with diffusivities of 4.46 × 10 −8 cm 2 /s (amikacin) and 2.08 × 10 −8 cm 2 /s (colistin), which are two orders of magnitude less than those in pure PEG gels where diffusion is controlled purely by gel tortuosity. The release and hindered diffusion can be understood based on the partial shielding of the charged groups within the loaded gel, and they have a significant effect on the antimicrobial properties of these gels. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys.2016, 54, 64–72 Abstract : Hydrogels have been extensively used for drug delivery. Typically, drugs are loaded during gel synthesis, and their release is controlled by diffusion out of the gel network. Electrostatic charge introduces a strong thermodynamic component to control loading and release. It enables PEG‐based gels to absorb high antibiotic concentrations after gel synthesis. Furthermore, electrostatic interactions slow antibiotic out‐diffusion during delivery. Even under pH and physiological salt conditions, antibiotic diffusivity is 100 times less than that in uncharged gels.