Characterization of Schiff base self-healing hydrogels by dynamic speckle pattern analysis

Abstract

Self-healing hydrogels are emerging materials capable of restoring functionality after damage, making them highly suitable for biomedical applications, such as tissue engineering, wound healing, and drug delivery. In this study, we synthesize and characterize a novel biodegradable, conductive, and selfhealing hydrogel. The synthesis is based on a Schiff base formed between gelatin and hyaluronic acid, and the dynamic reversible Schiff base bond provides the self-healing property. To characterize and assess the self-healing behavior of the hydrogel, dynamic speckle pattern (DSP) analysis is introduced as a non-destructive, non-contact, and easy-to-implement method. Speckle patterns are formed upon scattering of laser light from a diffusive matter and includes a huge overall information about the sample, to be extracted by statistical processing. DSP analysis is employed to monitor the self-healing process of the hydrogel at both macroscopic and microscopic scales. Experimental procedure involve in situ acquisition of speckle patterns over time under controlled environmental conditions, followed by statistical analysis to evaluate the internal dynamics of the healing process. Several statistical parameters are computed for real-time monitoring of the self-healing property of the hydrogel. The findings, on the one hand, underscore the potential of Schiff base hydrogels in advanced biomedical applications where self-healing properties are critical for sustained performance and longevity. On the other hand, the introduced analysis method shows its potential to serve as an effective approach for biomaterial characterization.Self-healing hydrogels are a class of smart and responsive materials that possess the remarkable ability to autonomously repair damage or cracks that may occur within their structure. This ability of self-healing can significantly increase the performance, life, and durability of these materials and make it a very interesting feature in various applications. Hydrogels are generally able to achieve self-healing by incorporation of reversible and dynamic crosslinking mechanisms to the hydrogel network. These dynamic crosslinks can be formed through a variety of chemical interactions, such as ionic interactions, hydrogen bonding, covalent dynamic bonds including Schiff base chemistry, host-guest interactions, disulfide linkages, and physical entanglements 1,2 . Self-healing hydrogel, based on Schiff base chemistry, is a class of responsive and dynamic polymeric material with the amazing capacity to self-repair damage or cracks in its structure. This self-healing ability is helped by the reversible nature of the Schiff base linkages, which are produced by dynamic covalent imine bond formation via the crosslinking of amine groups and aldehyde groups 3,4 . When the hydrogel experiences damage, the broken Schiff base bonds at the crack interfaces can spontaneously reform, allowing the material to heal and recover its structural integrity without the need for external intervention. Hydrogels constructed usi...