Table 1.

Comparison of the artificial blood and tissue used in different in vitro studies.

Artificial Blood	Advantages/Dis-Advantages	Advantages/Dis-Advantages	Advantages/Dis-Advantages
phosphate buffered saline (PBS) [46,47]	pH constant 7.4, the proximity of its ions to the ions of the body (%)	calcium alginate hydrogel [58]	stability at 37 °C, the feasibility to adapt gel strength and elasticity, mild gelling conditions, feasibility of incorporation the diverse substances such as proteins or living cells
9:1 (v/v) of normal saline and isopropanol [53]	suitable medium for in vitro release of sirolimus	3 wt.% alginate; 2 wt.% agar; 2 wt.% agarose; 10 wt.% PAA; 15 wt.% PVA [59]	agarose: long-term dissolution
deionized water, PBS, phosphate-buffer (PB) [34]	deionized water increased the release compared to PBS and PB	calcium alginate; polyacrylamide (PAAm); poly(vinylethy limidazolium bromide [61]	disadvantages of calcium alginate: dissolution of the network by monovalent cations (like Na+) and its susceptibility to microbial contamination
surfactant 0.1% P123 (kind of PEO–PPO–PEO block copolymers) in phosphate buffer pH 4.0 [54]	suitable for in vitro release of sirolimus	alginate-based gel containing microparticles LiChroprep® RP-18 or mediumchain triglycerides [64]	additives improved the transfer of hydrophobic drugs into the hydrogel but had no significant effect on the hydrophilic drugs
glycerol-water (40/60 vol%, 0.01% surfactant) [41,43]		deionized water, PBS, and PB as the base for preparing hydrogel [34]	more drug transfer to deionized waterbased hydrogels than PBS and PB-based hydrogels
2% ultra-pure sodium dodecyl sulfate (SDS), in high purity water with 10% gradient-grade acetonitrile (ACN), and buffered to pH 4.5 with phosphate+ 55:45:0.02 water/tetrahydrofuran (THF)/formic acid (v/v) [56]	good correlate between in vitro release profile with in vivo from porcine
87% of glycerol and 13% of water [45]	approaching to the viscosity of blood