Table 5.

Summary of example nanomaterials for osteoporosis.

Category	Nanomaterials	Active principle	Main results	Ref.
Drug carriers	Lipid nanoparticles	Hydroxyapatite, zoledronic acid	•typical biphasic release pattern [38.17 ± 2.12% (pH 7.4) and 64.2 ± 3.75% (pH 5) at 48 h] •exhibit a strong affinity towards HA	[208]
	PEGylated chitosan nanoparticles	PTH 1-34	•encapsulation efficiency of 40% •show an oral bioavailability of 100–160 pg/ml PTH 1–34 throughout 48 h	[209]
	Nanocrystalline hydroxyapatite particles	Pullulan/dextran polysaccharide	•retain subcutaneously local growth factors •induce the deposition of a biological apatite layer •favor the formation of a dense mineralized tissue subcutaneously in vivo	[210]
	Cerium nanoparticles	Cerium oxide, alendronate	•bone-targeted ability •pH-responsive activity •selectively eliminate mature osteoclasts without affecting preosteoclasts	[211]
	Nanodiamonds	Alendronate, nanodiamonds	•enhance ALP activity •effectively accumulate in bone tissues after intravenous administration	[212]
Gene therapy	Polyurethane nanomicelles	SDSSD peptide, anti-miR-214	•selectively bind to osteoblasts via periostin •enhance bone formation without overt toxicity or elicit an immune response	[213]
	Tetrahedral framework nucleic acids	miR-2861	•enable efficient miR-2861 unloading and deployment after intracellular delivery •inhibit the expression of HDAC5 and promote osteogenic differentiation	[214]
	PLGA nanoparticles	Polyethyleneimine-RANK siRNA	•significantly reduce (47%) RANK mRNA levels •suppress the differentiation of preosteoclasts to mature osteoclasts	[215]