Table 6.

Highlights of reviewed studies related to NPs application in hydrogels for wound healing.

Biomaterials	NP & size	Function	Mechanism of action	Concentration	In vivo	Main result	Ref
Acrylic acid	AgNP 39 nm Graphene N/A	Antibacterial	Damage to cell membrane and inhibition of DNA replication	AgNP 12.5 mg/mL Graphene 2.5 mg/mL	+	The highest antibacterial activity for hydrogel with the highest Ag to graphene mass ratio (5:1) (Ag5G1) against E. coli and S. aureus. Ag5G1 decreased inflammatory cells and enhanced fibroblast migration, collagen deposition, and microlevel formation in vivo.	[171]
Carboxymethyl cellulose (CMC)	ZnONPs N/A	Antibacterial and keratinocyte migration	Infiltrating into the bacteria membrane and damaging lipids and proteins [243]	Weight ratio of 10% to CMC	–	ZnONPs promoted loading efficiency of TC within the system and enhanced TC sustained release from the hydrogel.	[172]
Poly- (PEG citrate-co-N-isopropylacrylamide) (PPCN)	Cu framework NPs 285.6 ± 2.7 nm	Angiogenic and ECM protein expression	VEGF triggering and expression and collagen	100 mg/mL	+	Improved migration of HEKa cells, wound closure, angiogenesis, and collagen deposition, compared to PPCN.	[175]
3-(trimethoxysilyl) propyl methacrylate (MPS)MPS	CuNPs 10 nm	Antibacterial and angiogenic	Damaging the bacteria membrane and crosslinking proteins. VEGF triggering	0.5, 1, and 1.5 mg/mL	+	When exposed to near-infrared (NIR) light irradiation, the composite hydrogel showed an antibacterial effect against S. aureus and E. coli. In vivo angiogenesis and wound healing are supported by CuNPs-containing hydrogels compared to the hydrogel control.	[177]
Glycidyl methacrylate functionalized quaternized chitosan (QCSG)	CNT Diameter of 10–20 nm and length of 10–30 μm	Conductivity (1.2 × 10−1 S/m) Hemostatic capability	Transferring electrical signals to activate platelets and growth factors controlling wound healing	2, 4, and 6 mg/mL	+	CNT containing cryogels showed better hemostatic capability response compared with gauze and gelatin hemostatic sponge in different mouse and rabbit injury models, and better wound healing ability and less inflammatory response compared to pristine cryogel and Tegaderm™ dressing.	[181]
Hyaluronic acid-graft-dopamine	rGO N/A	Conductivity (2.5 × 10−4 S/m)	Electrical signals transfer and stimulating excitable skin cells	0.2%, 0.6%, and 1% w/v	+	Photo-thermal antibacterial activity against both E. coli and S. aureus. Enhanced vascularization, granulation tissue thickness, and collagen deposition in vivo.	[186]
Chitosan	Carbon dots (CDs) 4 ± 1 nm	Antibacterial pH-sensitivity	Destroying cell membranes, inducing free radicals [244]	0.25%, 0.5%, 1%, and 2%	+	Antibacterial activity is enhanced with an increase in CD concentration within hydrogels against S. aureus. CDs containing hydrogels promoted wound closure.	[188]