Synthesis, Properties, and Biocompatibility of 4-Carboxyphenyboronic Acid-Modified Gelatin-Methacryloyl: A Hydrogel for Retinal Surgeries

The current surgical adjunctive for vitreoretinal surgeries fails to provide an adequate 3D structure for cellular regeneration. A one-pot synthesis of gelatin-methacryloyl (GelMA) followed by modification with 4-carboxyphenylboronic acid (4-CPBA) was performed to fabricate 4-CPBA-modified GelMA (4CPBA@GelMA), a gelatin-based hydrogel. 4CPBA@GelMA was photo-cross-linked by 405 nm violet light and examined using nuclear magnetic resonance (NMR), Fourier-transform infrared spectrometry (FTIR), scanning electron microscopy (SEM), and rheometry. In vitro biocompatibility was examined by Müller cell proliferation assays exposed to 4CPBA@GelMA and violet light. In vivo retinal biocompatibility was evaluated by electroretinography of rat eyes that were exposed to intravitreally injected and photo-cross-linked 4CPBA@GelMA at days 3, 7, 14, and 28 post-injection. Following electroretinography, histology and immunohistochemistry were performed on the retinas. The NMR results indicated amidation of GelMA by 4-CPBA, and FTIR confirmed the presence of the CPBA ring in 4CPBA@GelMA samples. SEM revealed that 4CPBA@GelMA had significantly larger pores than GelMA (56.9 ± 9.5 vs 35.1 ± 2.8 μm;