From:  Engineering the microenvironment: advanced biomaterials for humanized in vitro immunotoxicology and carcinogenicity assessment

 Key biomaterial types and their roles in ECM mimicry.

Biomaterial categorySpecific examplesKey properties
(biocompatibility, degradability, mechanical tunability, cell adhesion motifs)
Contribution to ECM mimicry
(compositional, structural, mechanical, biochemical cues)
Advantages of in vitro modelsAssociated challenges
Natural polymersCollagen, fibrin, hyaluronic acid (HA), gelatin, alginate, chitosan, silk fibroinHigh biocompatibility [83], low immunogenicity [84], inherent cell adhesion sites (e.g., RGD) [67], enzymatic degradability [66].Compositional: mimic native ECM proteins/polysaccharides [63].
Structural: form hydrogels, fibrous networks [64].
Biochemical: present cell-binding motifs, sequester growth factors [76].
Excellent biological relevance, support cell growth/differentiation, tunable properties [66].Variable batch-to-batch consistency, potential for immunogenicity (though low) [84], limited mechanical strength for some [85].
Synthetic polymersPolyethylene glycol (PEG), polyisocyanide (PIC), polyacrylamide (PAAm), polyvinyl alcohol (PVA)High tunability in physical/chemical properties, controllable degradation, low immunogenicity, resistance to non-specific protein adsorption [68, 69].Structural: precise control over architecture, porosity.
Mechanical: tunable stiffness/elasticity [73].
Biochemical: functionalizable with specific cues [30].
Greater control over properties, reduced variability, avoids animal-derived components, can be stimuli-responsive [79].Often lack intrinsic bioactivity/cell adhesion, may require functionalization, potential cytotoxicity from residues [86].
Composite (semi-synthetic) biomaterialsGelatin methacryloyl (GelMA), HA-PEG compositesCombines bioactivity of natural polymers with tunability/stability of synthetics; photopolymerizable, customizable mechanical properties [62, 87].Comprehensive mimicry (compositional, structural, mechanical, biochemical) by integrating the best features of both categories [88].Broad range of adjustable properties, enhanced physiological relevance, improved printability for bioprinting [89].Balancing properties can be complex, potential for residual toxicity from crosslinking agents, regulatory hurdles for novel combinations [70].
Bioinks (specialized for 3D bioprinting)GelMA, HAMA, alginate, recombinant spider silk proteins, cell aggregatesTunable rheological properties (shear-thinning) [90], rapid gelation post-printing, biocompatibility, cell encapsulation capability [78].Enables precise spatial patterning of cells and ECM components, vascularized channels, biochemical gradients, tissue-mimetic stiffness [77, 91].Allows for complex, high-resolution 3D tissue constructs, high reproducibility, scalability for HTS [77].Cytotoxicity due to UV light/free radicals (for photopolymerizable), oxygen inhibition, long printing times, need for more relevant ECM mimics [78].