What is Hydrogel?

Hydrogels are a class of widely studied and applied biomaterials. Hydrogels have been widely studied as cell scaffolds and drug delivery vehicles because their chemical and physical properties are very close to the natural environment of cells. Hydrogels can encapsulate both cells and biomolecules, and many gel systems can closely control the release properties through systematic changes in the physical and chemical structure of the gel. Hydrogels can be formed from synthetic (e.g., poly(ethylene glycol), poly(hydroxyethyl methacrylate)) and naturally occurring polymers (e.g., collagen, hyaluronic acid, heparin). Due to their high water content, hydrogels are able to form in the presence of cells, proteins and DNA. Among them, the versatility and excellent biocompatibility of PEG macromolecular chemistry have facilitated the development of numerous intelligently designed hydrogel systems for regenerative medicine applications.

PEG hydrogels have been widely used for cell encapsulation and therapeutic protein delivery due to their tissue-like water content, adjustable physicochemical properties and resistance to nonspecific protein adsorption. Through copolymerization with other macromolecules, it is easy to introduce multiple functional groups into PEG hydrogels to inhibit or promote cell survival and function. Chemical or covalent crosslinking is the most commonly used hydrogel crosslinking mechanism, which leads to relatively stable hydrogel structures and tunable physicochemical properties such as permeability, molecular diffusivity, equilibrium water content, elasticity, modulus amount and degradation rate. Among them, chain-growth and step-growth polymerization cross-linking reactions can adjust the mesh size of the hydrogel to control protein release. The mesh size is usually controlled by changing the molecular weight and concentration of monomers. For example, hydrogels with mesh size smaller than the hydrodynamic radius of the encapsulated proteins will result in sustained release of proteins.

PEGylation Analysis Capabilities

l PEGylation purity and extent analysis

l Hydrodynamic diameter of PEGylated species

l Surface charge of PEGylated substances

l Speciation analysis of PEGylated substances

l Evaluation of degree of substitution with PEG