Sequentially crosslinked collagen‐based hydrogel to form a semi‐interpenetrating network for enhanced stability to hydrolytic degradation and electrochemical properties

Biodegradable polymers are pivotal in tissue engineering, facilitating long‐term tissue reintegration and reducing the necessity for surgery. However, collagen, a crucial component of the extracellular matrix, encountered challenges due to its limited mechanical strength and rapid in‐vivo degradation. This study addresses these issues through crosslinking and functionalizing collagen with synthetic 4‐arm amine‐terminated polyethylene glycol (PEG) in a semi‐interpenetrating network (IPN) hydrogel. The first goal is to enhance resistance to hydrolysis, thus extending the biodegradation rate. Then, to explore its electrical conductivity properties for certain applications like neural tissue regeneration. The hydrogels were fabricated using sequential IPN formation synthesis where their structural stability and type of degradation by‐products were confirmed using Fourier‐transform infrared spectroscopy (FTIR), Raman spectroscopy, scanning electron microscopy (SEM), and nuclear magnetic resonance (NMR). Next, its mechanical and degradation properties investigations exhibit a 92% enhancement in hardness and a 90% retainment of its initial mass over time under physiological conditions. Additionally, the introduction of polypyrrole (PPy) via in‐situ polymerization increases its electrical conductivity, achieving a remarkable 104‐fold increase at a 0.75 M concentration, attributed to the interconnectivity of PPy chain networks within the three‐dimensional structure of IPN collagen/PEG hydrogel. The increased PPy concentration improves conductivity and reduces energy requirements for redox reactions, ensuring electrochemical stability as revealed by cyclic voltammetry analysis. The demonstrated structural and electrochemical stability of the semi‐IPN collagen/PEG/PPy hydrogel within a physiological environment through a facile sequential crosslinking method underscores its promising practical applications in enhancing clinical effectiveness.