Table 3.

Summary of wound healing studies evaluating the effects of CS-based NPs, CMCSNPs, CNPs, and CS-modified metal NPs on collagen deposition.

NP formulation	Active ingredient	Encapsulation efficiency	Diameter	Surface charge	Wound model (Animal)	Key findings	Ref.
Therapeutic compound loaded CS-based NPs
CSNPa	GA	73.20% ± 2.10%	252.90 ± 3.09 nm†	+33.50 ± 0.30 mV	Excision wound (Male Wistar rat)	• Collagen and hexosamine content were the highest in the collagen-fibrin scaffold containing GA-loaded CSNP treatment group (≈0.4 mg/100 mg dry weight) as compared to the control group (≈0.25 mg/100 mg dry weight) and unloaded collagen-fibrin scaffold treatment group (≈0.3 mg/100 mg dry weight).	[143]
CSNPa	CUR	93.00% ± 5.00%	359 ± 65 nm†	−10.70 ± 0.10 mV	Full-thickness wound (Male Wistar rat)	• Highest collagen density was obtained in the PCL-gelatin containing CUR-loaded CSNP group (49.6% ± 5.6%) • Control group and PCL-gelatin group had collagen densities of 7.6% ± 3.0% and 12.1% ± 3.2%, respectively.	[156]
Lecithin/CSNPg	MEL	27%	160.43 ± 4.45 nm†	+25.00 ± 0.57 mV	Diabetic full-thickness wound (Wistar rat)	• No significant difference in collagen content was observed between MEL-loaded lecithin/CSNP (≈50.7), MEL alone (≈63.0), blank lecithin/CSNPs alone (≈44.8), and the vehicle control group (≈43.5).	[166]
CMCSNPs
CMCS-OH30 NPd	OH30	82.46% ± 1.11%	258.70 ± 13.30 nm†	+30.20 ± 5.10 mV	Full-thickness wound (Female Kunming mice)	• Wounds treated with OH30-loaded CMCSNPs had a collagen I/collagen III ratio of 1.875 while control wounds had a collagen I/collagen III ratio of 12.22. • Highest total collagen content was observed in the control group, followed by the blank CMCSNP group, OH30 group, and the OH30-loaded CMCSNP group.	[120]
ChitinNPs
CNPg	–	–	14 ± 3 nm§	–	Full-thickness wound (Male Sprague-Dawley rat)	• CNP-based aerogel group (collagen density ≈ 40%) had the highest average collagen density. • CNP-based cryogel group (collagen density ≈ 35%) had similar levels of collagen density as the positive control (DuoDERMⓇ) (collagen density ≈ 35%). • The control group only had a collagen density of approximately 20%	[158]
CS-modified metal NPs
PVA/CS-AgNP#	Ag	–	190 – 200 nm†,§	–	Full-thickness wound (Male Wistar rat)	• PVA/CS-AgNPs produced a hydroxyproline content of 27.53 ± 0.47 mg/g which was close to the amount present in the original tissue and was about 1.6 times higher than the control group.	[134]
PVA/COS-AgNP#	Ag	–	–	–	Full-thickness wound (Male Sprague-Dawley rat)	• The relative hydroxyproline content in the PVA/COS-AgNP group (≈0.5 by day 3) was significantly higher than the control group (≈0.3 by day 3). • PVA/COS-AgNP group had more rapid collagen I and III formation than the control group.	[159]
CS-AgNP#	Ag	–	15 nm§	–	Burn wound (Male Sprague-Dawley rat)	• Significantly higher hydroxyproline content was observed in the CS-AgNP group (4.90 ± 0.05 mg/g) as compared to the control (4.59 ± 0.20 mg/g) and SSD (4.57 ± 0.20 mg/g) groups.	[141]
PVA/COS-AgNP#	Ag	–	15.31± 4.00 nm§	–	–	• HSF cells treated with PVA/COS-AgNP nanofibres (hydroxyproline content = 0.1092) produced significantly higher hydroxyproline than the untreated group (hydroxyproline content = 0.0896).	[167]

^aPrepared using ionic gelation method with TPP as a cross-linker.

^dPrepared using ionic gelation method with a mixture of CMCS and OH30.

^gPrepared using self-assembly.

^#Prepared using chemical reduction method.

^†Size measured using DLS.

^§Size measured using TEM.