Development and Characterization of Insulin-Loaded Collagen Hydrogels as Multifunctional Biomaterials for Advanced Biomedical Applications

Abstract

The behavior of insulin encapsulation within collagen-based hydrogels was investigated to explore their potential for biomedical applications. Incorporating insulin into the hydrogel matrix significantly influenced both structural and functional properties. Increasing the insulin content up to 60 µg per gel accelerated the gelation process and enhanced the swelling capacity, reaching values of up to 3800%. However, optimal crosslinking was observed at lower insulin content (15 µg), suggesting the formation of stabilizing urea-type interactions during simultaneous crosslinking with a bioactive polyurethane component. Morphological analysis revealed that insulin incorporation led to smoother and less porous surfaces, indicating a more compact network structure. Mechanically, insulin-loaded hydrogels exhibited improved resistance, sustaining deformation up to 18% under 3.2 million fatigue cycles, highlighting their durability under repetitive stress conditions. Higher insulin concentrations (30–60 µg) promoted a superabsorbent behavior, with swelling values ranging from 3500% to 5600%, strongly dependent on pH conditions and notably enhanced at skin-relevant pH. In addition, the presence of insulin improved resistance to both hydrolytic degradation and enzymatic biodegradation in the presence of pepsin, with the highest stability observed at 60 µg. The materials demonstrated good hemocompatibility and showed controlled surface erosion upon exposure to simulated body fluids. Interestingly, hydroxyapatite deposition was detected through Alizarin Red staining, with a qualitative increase at higher insulin contents, suggesting potential bioactivity toward mineralization processes. Overall, these findings highlight the multifunctional role of insulin beyond its therapeutic activity, acting as a structural and bioactive modulator in collagen-based hydrogels, opening new opportunities for advanced biomedical applications.