Table 2.

Summary of nanofibers (NFs) and microspheres

Vectors	Delivery mode	Advantages	Drawbacks	Examples	Mechanism	Effects
Nanofibers (NFs)	Surface adsorption or nanofiber encapsulation	Excellent ability to capture drugs; high specific surface area and porosity; ability to promote osteogenic differentiation and adhesion of BMSCs together with drug delivery	Lack of tissue-specific delivery, resulting in off-target effects and cytotoxicity; weak intracellular uptake	Gelatin nanofibers/miR-29 inhibitors (James et al., 2014)	Upregulate the mRNA levels of both IGF-1 and TGF-β1	Increase the synthesis of osteonectin and type I collagen
				Polycaprolactone (PCL) nanofibers/siRNA-MSN@PEI (Pinese et al., 2018)	Silence the expression of COLL1A1	Inhibit fibrous capsule formation to promote host-implant integration
Microspheres	Surface adsorption or encapsulation inside the microsphere	Sustained drug release; targeted drug delivery; biocompatibility and biodegradability; improved drug efficacy and patient compliance; prevention of nuclease degradation	Sudden release phenomenon in clinical applications; difficulty in large-scale preparation; biocompatibility issues of modified microspheres	Degradable polymer microspheres/miR-26a (Zhang et al., 2016)	Inhibit the expression of Gsk-3β	Promote bone regeneration