Extracellular matrix (ECM) hydrogels are biomaterials derived from native tissues after removal of cellular components through decellularization. The remaining matrix preserves key structural proteins (such as collagens, elastin, fibronectin, and laminin), proteoglycans, and glycosaminoglycans that define the biochemical and architectural identity of the source tissue. ECM is naturally produced by cells in all tissues and provides both mechanical support and biochemical signaling cues.

Superabsorbent polymer (SAP) hydrogels are three-dimensional, crosslinked polymer networks capable of absorbing and retaining extremely large amounts of water—often hundreds to thousands of times their own weight—while remaining insoluble. Their structure is based on hydrophilic polymer chains containing functional groups such as carboxylate, hydroxyl, or amide moieties, which generate strong osmotic driving forces for water uptake.

Polyacrylamide (PAM) hydrogels are synthetic, water-swollen polymer networks formed from acrylamide monomers chemically or physically crosslinked into a three-dimensional structure. Polyacrylamide itself is an organic polymer composed of repeating acrylamide subunits, and when crosslinked in aqueous environments, it forms soft, highly hydrated gels with tissue-like mechanical behavior. PAM hydrogels are entirely synthetic and industrially produced, offering high batch-to-batch reproducibility and tunable properties.

Polymethyl methacrylate (PMMA) is a synthetic, thermoplastic polymer belonging to the acrylic resin family. It is formed by the free-radical polymerization of methyl methacrylate (MMA) monomers, resulting in a linear, amorphous polymer with high optical clarity and structural rigidity. PMMA is entirely industrially produced, with MMA synthesized from petrochemical feedstocks and polymerized using controlled thermal, chemical, or photochemical initiation.

Poly(lactic-co-glycolic acid) (PLGA) is a synthetic, biodegradable aliphatic polyester obtained by the copolymerization of lactic acid and glycolic acid. It is an industrially produced polymer derived from renewable monomers that are metabolized through natural biochemical pathways. PLGA is synthesized primarily via ring-opening polymerization of lactide and glycolide, allowing precise control over molecular weight, copolymer ratio, and end-group chemistry.