Injectable Biodegradable Hydrogels

Abstract

Injectable biodegradable copolymer hydrogels, which exhibit a sol–gel phase transition in response to external stimuli, such as temperature changes or both pH and temperature (pH/temperature) alterations, have found a number of uses in biomedical and pharmaceutical applications, such as drug delivery, cell growth, and tissue engineering. These hydrogels can be used in simple pharmaceutical formulations that can be prepared by mixing the hydrogel with drugs, proteins, or cells. Such formulations are administered in a straightforward manner, through site‐specific control of release behavior, and the hydrogels are compatible with biological systems. This review will provide a summary of recent progress in biodegradable temperature‐sensitive polymers including polyesters, polyphosphazenes, polypeptides, and chitosan, and pH/temperature‐sensitive polymers such as sulfamethazine‐, poly(β‐amino ester)‐, poly(amino urethane)‐, and poly(amidoamine)‐based polymers. The advantages of pH/temperature‐sensitive polymers over simple temperature‐sensitive polymers are also discussed. A perspective on the future of injectable biodegradable hydrogels is offered.magnified image

Hydrogels: Methods of Preparation, Characterisation and Applications

“…sensitive polymers including polyesters, polyphosphazenes, polypeptides, and chitosan, and pH/temperature-sensitive polymers such as sulfamethazine-, poly(b-amino ester)-, poly(amino urethane)-, and poly(amidoamine)-based polymers is reviewed recently by Nguyen and Lee (2010). Recent progresses in the development and applications of smart polymeric gels have been reviewed extensively by Masteikova, Chalupova et al (2003) and Chaterji, Kwon et al (2007).…”

Study of Tissue Printing Parameters for Generating Complex Tissue Constructs

“…Hydrogels have a structure that is similar to the extracellular matrix (ECM) of many tissues, which will help with the cell integration [1,6,7]. Hydrogels also have the ability to homogenously encapsulate cells [1][2][3][4][5][6]. The natural biopolymer SeaKem agarose hydrogel was adapted as the in-situ scaffolding material.…”

“…In the United States 18 people die daily waiting for an organ and more than 117,000 men, women and children await a life-saving organ transplant. Recently, 3D printing techniques are being employed to create complex biological structures with the long term goal of organ construction [1][2][3][4][5]. In this process, cells need to be seeded and cultured on printed scaffolds to generate tissue in a subsequent step.…”

Encapsulation technologies in beta cell replacement therapies for Type 1 diabetes

“…This is because crosslinking results in the formation of elastic alginate capsules with better stability and superior mechanical strength [108,109]. Barium crosslinking has been reported to be less immunogenic [110] than APA (or other polycation-linked) capsules, while providing sufficient protection from antibody and cytokine-mediated islet-damage.…”