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Glucose-Sensitive Drug Delivery Systems Based on Phenylboronic Acid for Diabetes Treatment
Published in Peter Grunwald, Pharmaceutical Biocatalysis, 2019
Li Zhao, Bozhong Lin, Liyan Wang, Guangqing Gai, Jianxun Ding
The formation of hydrogels was the cooperative interaction of the inclusion complexation between PEG and α-CD, and the dynamic covalent bond between PBA and PVA. The content of α-CD played an important role in the property of hydrogels. The gelation time could be shorted by increasing the content of α-CD with enhanced structural recovery ability. Hydrogels based on PBA-diol cross-linked binding were also obtained by block glycopolymer, which was fabricated by the copolymerization of AAPBA and 2-lactobionamidoethyl methacrylate (LAMA) conducted by RAFT method (Cai et al., 2017). Another block glycopolymer, (3-propionamidophenyl)boronic acid (N-(3-((2,3,4,5,6-pentahyd roxyhexyl)amino)propyl)propionamide), formed injectable self-healing hydrogels through PBA–glucose complexation within the glycopolymer (Dong et al., 2016). The injectable self-healing hydrogels controlled the payload release triggered by glucose. Glycopolymer hydrogels provide an alternative design of glucose-sensitive drug delivery systems.
Recent development and biomedical applications of self-healing hydrogels
Published in Expert Opinion on Drug Delivery, 2018
Yinan Wang, Christian K. Adokoh, Ravin Narain
Self-healing hydrogels that are associated with better resemblance to soft tissues have become the preferred biomaterials for various applications. They are generally designed and fabricated with biocompatible materials that provide specific and distinct responses to various physiological or externally applied stimuli. Healing at a damage site of hydrogel could be initialized by several driving forces such as reconstructive covalent dangling side chain or non-covalent hydrogen bonding, thermally reversible reactions, ionomeric arrangements, or molecular interactions and entanglement. Two kinds of cross-linking approaches such as physical interaction and chemical covalent approaches are generally utilized for the construction of hydrogel networks. There are still challenges with these two approaches; for example, intrinsic irreversibility of covalent bonding still remains the main setback of chemical cross-linking hydrogels. Non-covalently bonded system, which is cross-linked by physical interactions, has been exploited to avoid the issue. Physically cross-linked hydrogels are transient and can temporally be stressed by various stimuli (such as temperature, shear force, pH, etc.) and recover immediately after the removal of external stimuli. This approach has led to the development of excellent injectable and self-healing properties that can satisfy the urgency of minimally invasive surgery. Ideally, self-healing hydrogels should be produced from inexpensive to nontoxic/non-hazardous materials and techniques, and should not degrade prematurely. As demonstrated by a growing number of investigators, self-healing hydrogels are endowed with tunable, high storage modulus, shear thinning properties, controllable and even biomimetic behavior well-suited for cell culture, drug delivery and tissue engineering or regenerative growth applications. Besides self-healing, this type of hydrogel can be made injectable and pH sensitive, and may hold promise for better applications in cancer therapy. As a new type of biomaterial, self-healing hydrogels have been considered as an alternative to traditional injectable hydrogels. It is now clear from several researches reported approach that self-healing hydrogels could homogeneously encapsulate pharmaceutical drugs/cells ex vivo under physiology conditions, resulting in better repeatable experimental results and higher therapeutic activities of drugs and cells. However, it is not surprising that self-healing hydrogels have been considered as an alternative to traditional injectable hydrogels. In this review, recent developments and challenges regarding self-healing hydrogels have been widely covered. We first investigated the strategies of making self-healing hydrogels and their healing mechanisms. This is followed by the self-healing hydrogels’ applications in biomedical fields such as 3D/4D printing, cell/drug delivery, as well as soft actuators.