Table 6.

NIR light-responsive release systems for bone tissue engineering

Release systems	Photoresponsive agents	Wavelength (nm)	Power density	Osteogenic agents	Mechanisms	References
Photocaged UCNTs@mesoporous silica nanoparticles	Photocaged UCNTs	980	1 W·cm-2	Ca2+	Photocaged UCNTs regulate the intracellular calcium and stem cells differentiation by NIR light	Kang H. et al. 110
BP-SrCl2/PLGA microspheres	BP nanosheets	808	1 W·cm-2	Sr2+	NIR light triggers a local temperature rise and destroys the PLGA shells to release Sr2+	Wang X. et al. 29
Poly(ε-caprolactone) (PCL) networks	IR-26 dye	1064	50 mJ	SDF-1α	NIR light triggers the shape switch of PCL networks to release SDF-1α	Tuncaboylu D. C. et al. 111
Biomimetic anti-inflammatory nanocapsule (BANC)	Gold nanocage	808	3 W·cm-2	RvD1	NIR triggers the release of RvD1 to induce the M2 polarization of macrophage cell	Yin C. et al. 22
Heat-activated and dimerizer-dependent transgene expression system	Hollow gold nanoparticles	808	11-17 mW·mm-2	BMP-2	Hyperthermia triggered by NIR laser activates the BMP-2 expression of cell constructs	Sanchez-Casanova S. et al. 21

UCNTs: Upconversion nanotransducer, BP: Black phosphorus, PLGA: Poly(lactic-co-glycolic acid), SDF: Stromal cell-derived factor, RvD1: Resolvin D1, BMP: bone morphogenetic proteins.