Silver nanoparticle/chitosan oligosaccharide/poly(vinyl alcohol) nanofibers as wound dressings: a preclinical study

Figures & data

Table 1 Conductivity of the PVA/COS solutions

Components	Conductivity (mS cm^−1)
PVA:COS = 2:1	2.43 ± 0.04
PVA:COS = 3:1	1.89 ± 0.03
PVA:COS = 4:1	1.79 ± 0.04
PVA:COS = 5:1	1.45 ± 0.08
PVA:COS:1% AgNO3	2.73 ± 0.09
PVA:COS:2% AgNO3	2.76 ± 0.02
PVA:COS:3% AgNO3	2.80 ± 0.06
PVA:COS:4% AgNO3	2.72 ± 0.03
PVA:COS:5% AgNO3	2.71 ± 0.08
PVA:COS-AgNPs	3.21 ± 0.14

Abbreviations: AgNPs, silver nanoparticles; COS, chitosan oligosaccharide; PVA, poly(vinyl alcohol).

Figure 1 (A) Scanning electron micrographs of (a1) the neat PVA/COS nanofiber, (a2) the PVA/COS/3% AgNO₃ nanofiber, and (a3) the PVA/COS-AgNP nanofiber. (B) Diameter distribution of (b1) the neat PVA/COS nanofiber, (b2) the PVA/COS/3% AgNO₃ nanofiber and (b3) the PVA/COS-AgNPs nanofiber. (C) Field emission transmission electron micrographs of (c1) the non-UV-treated PVA/COS/3% AgNO₃ nanofiber (c2) the post-UV-treated PVA/COS/3% AgNO₃ nanofiber, and (c3) the PVA/COS-AgNP nanofiber.

Abbreviations: AgNP, silver nanoparticle; COS, chitosan oligosaccharide; PVA, poly(vinyl alcohol); UV, ultraviolet; Std dev, standard deviation.

Figure 2 Ultraviolet-visible spectra for the nanofiber aqueous solutions. (A) The neat PVA/COS nanofiber, (B) the non-ultraviolet-treated PVA/COS/AgNO₃ nanofiber, (C) the PVA/COS/AgNO₃ nanofiber, (D) the PVA/COS-AgNP nanofiber, and (E) COS-AgNPs.

Abbreviations: AgNP, silver nanoparticle; COS, chitosan oligosaccharide; PVA, poly(vinyl alcohol); AU, absorbance units.

Figure 3 X-ray diffraction curves for (A) the PVA/COS/AgNO₃ nanofiber and (B) the PVA/COS-AgNP nanofiber.

Abbreviations: AgNP, silver nanoparticle; COS, chitosan oligosaccharide; PVA, poly(vinyl alcohol).

Figure 4 Fourier transform infrared spectra of (A) the neat PVA/COS nanofiber, (B) the PVA/COS/AgNO₃ nanofiber, and (C) the PVA/COS-AgNP nanofiber.

Abbreviations: AgNP, silver nanoparticle; COS, chitosan oligosaccharide; PVA, poly(vinyl alcohol).

Figure 5 Differential scanning calorimetric thermograms for the (A) PVA nanofiber, (B) the neat PVA/COS nanofiber, (C) the PVA/COS/AgNO₃ nanofiber, and (D) the PVA/COS-AgNP nanofiber.

Abbreviations: AgNP, silver nanoparticle; COS, chitosan oligosaccharide; PVA, poly(vinyl alcohol); au, arbitrary units.

Figure 6 Water vapor permeability of (A) the PVA/COS nanofibers with a volume ratio of 2:1 cross-linked by glutaraldehyde vapor at various intervals and (B) the neat and drug-loaded nanofibers.

Abbreviations: AgNP, silver nanoparticle; COS, chitosan oligosaccharide; PVA, poly(vinyl alcohol).

Figure 7 Degree of swelling and weight loss from (A) the PVA/COS nanofibers with a volume ratio of 2:1 cross-linked with glutaraldehyde vapor at various intervals and (B) the neat and drug-loaded nanofibers.

Abbreviations: AgNP, silver nanoparticle; COS, chitosan oligosaccharide; PVA, poly(vinyl alcohol).

Figure 8 In vitro Ag release profiles from the PVA/COS-AgNP nanofiber and the PVA/COS/AgNO₃ nanofiber.

Abbreviations: AgNP, silver nanoparticle; COS, chitosan oligosaccharide; PVA, poly(vinyl alcohol).

Figure 9 Cytotoxicity tests from the MTT assays of cell viability. Absorbance was normalized to that of the negative control at each time interval, and was considered 100%.

Notes: *P<0.05 compared with the negative control. The data are presented as the mean ± standard deviation (n=5).

Abbreviations: AgNP, silver nanoparticle; COS, chitosan oligosaccharide; PVA, poly(vinyl alcohol).

Table 2 Average primary skin irritation index values for single application (n=4)

Samples	Average score
	1 hour	24 hours	48 hours	72 hours
PVA/COS/AgNO3 nanofiber mat	0.05 ± 0.10	0.00 ± 0.00	0 ± 0.00	0 ± 0.00
PVA/COS-AgNP nanofiber mat	0.28 ± 0.19	0.18 ± 0.13	0.05 ± 0.10	0 ± 0.00
Gauze	0.16 ± 0.21	0.10 ± 0.20	0 ± 0.00	0 ± 0.00

Abbreviations: AgNP, silver nanoparticle; COS, chitosan oligosaccharide; PVA, poly(vinyl alcohol).

Table 3 Average primary skin irritation index values for multiple applications (n=4)

Samples	Average score
	1 hour	24 hours	48 hours	72 hours
PVA/COS/AgNO3 nanofiber mat	0.10 ± 0.12	0.13 ± 0.15	0.08 ± 0.15	0.05 ± 0.10
PVA/COS-AgNP nanofiber mat	0.03 ± 0.05	0.05 ± 0.10	0.05 ± 0.10*	0.03 ± 0.05
Gauze	0.10 ± 0.14	0.18 ± 0.13	0.23 ± 0.05	0.10 ± 0.08

Note:

* P<0.05 compared with gauze.

Abbreviations: AgNP, silver nanoparticle; COS, chitosan oligosaccharide; PVA, poly(vinyl alcohol).

Figure 10 Zone of inhibition test for (A and D) the neat PVA/COS nanofiber (B and E) the PVA/COS/AgNO₃ nanofiber, and (C and F) the PVA/COS-AgNP nanofiber. Also shown are photographs of the disk sensitivity test for Staphylococcus aureus (A–C) and Escherichia coli (D–F).

Abbreviations: AgNP, silver nanoparticle; COS, chitosan oligosaccharide; PVA, poly(vinyl alcohol).

Figure 11 Bactericidal kinetic study against Staphylococcus aureus (A) and Escherichia coli (B) for the different nanofibers.

Abbreviations: AgNP, silver nanoparticle; COS, chitosan oligosaccharide; PVA, poly(vinyl alcohol); UV, ultraviolet.

Figure 12 Wound appearance at 1, 7 and 14 days after grafting with (A) gauze, (B) the PVA/COS/AgNO₃ nanofiber, (C) the PVA/COS-AgNP nanofiber, and (D) the commercial woundplast.

Abbreviations: AgNP, silver nanoparticle; COS, chitosan oligosaccharide; PVA, poly(vinyl alcohol).

Figure 13 Wound healing with the PVA/COS/AgNO₃ nanofiber, the PVA/COS-AgNP nanofiber, commercial woundplast, and gauze.

Notes: *P<0.05 compared with the gauze. The data are presented as the mean ± standard deviation (n=6).

Abbreviations: AgNP, silver nanoparticle; COS, chitosan oligosaccharide; PVA, poly(vinyl alcohol).

Figure 14 Histological examination after wounds had been covered for 7 and 14 days with (A) gauze, (B) the PVA/COS/AgNO₃ nanofiber, (C) the PVA/COS-AgNP nanofiber, and (D) the commercial woundplast.

Abbreviations: AgNP, silver nanoparticle; COS, chitosan oligosaccharide; PVA, poly(vinyl alcohol).