Table 3.

Synthetic biomaterial candidates for retinal ECM modelling in vitro.

Material	Origin	Advantages	Disadvantages	Neuronal support	References
Polyacrylamide	Mixture of acrylamide and bis-acrylamide	High reproducibility Strong mechanical homogeneity Citocompatibility Independent tunable stiffness	Bioinert, needs to be functionalized with ECM components	Soft hydrogels promote neural extension	(40, 219, 222, 226, 227)
PDMS	Mixture of an elastomer base (PDMS oligomers, a platinum catalyst and silica) and a curing agent	Biocompatibility High oxygen permeability Thermal stability High protein binding capability Tunable mechanical properties	Bioinert, needs to be functionalized with ECM components	CNS compliant Promotes the differentiation of different retinal cells, including RGCs, in retinal organoids	(11, 230, 231, 236, 238, 239, 241)
PEG	Polymer of ethylene oxide that display a variety of crosslinked end groups	Biocompatibility Low citotoxicity Hydrophilic; good metabolite diffussion	Bioinert, requires functionalization by ECM protein Limited amount of protein that can be coupled to the gel substrate that can lead to weak adhesions Stiffness cannot be independently tuned	Expansion of neural progenitor cell cultures and differentiation to glial cells Retinal organoid culturing	(238, 242, 243, 246, 248, 250)