TABLE 1.

Main required properties for adhesive tissue engineering scaffolds (ATESs).

Property	Characterization method	Design considerations	Approach considerations	Target value
Adhesive properties	Tensile adhesion test; shear adhesion test; wound closure test; burst pressure test; peeling test	Adhesion firmly after applying and in long term; tolerance of wet condition and stresses	Implying covalent and non-covalent interactions	Adhesion strength 1KPa–1MPa
Biocompatibility and low cell toxicity	AlamarBlue; MTT; in vivo compatibility tests	Low cell and tissue toxicity that allow cell growth and tissue regeneration	Using bio-compatible materials and adhesion mechanisms	Usually higher cell survival rates are preferred.
Biodegradation and swelling behavior	In vivo and in vitro degradation and swelling tests	Low swelling ratios that do not affect design pattern or exert pressure to tissue; proper degradation behavior that accommodates tissue regeneration rate	Choosing proper materials with intrinsic low swelling behavior and proper degradation rate; proper crosslink density; proper chain length for polymers	Low swelling ratio is preferred; 20–25% of materials is left after 4 weeks of degradation in vivo
Porosity and vasculature	SEM; microscopy	Incorporation of vasculature or choosing materials with adequate porosity	3D printed vascular system or choosing a proper base material and proper concentration and crosslink density	Optimal porosity and pore size highly depend on the tissue type and the specific application
Young’s modulus and stiffness	Mechanical tests: indentation test; compression test	Strong enough for bone and cartilage repair; soft enough for patient comfort for corneal repair; ability to withstand tensile stress for nerve repair	Choosing proper material, concentration, and crosslink density	1 KPa–100 MPa for cartilage and bone; 100 Pa – 100 KPa for corneal; and typically 100 Pa – 100 KPa for other tissues