No abstract

In this study, nanocomposite collagen scaffolds incorporating gold nanoparticles (AuNPs) were prepared for wound healing applications. Initially, dose (<20 ppm) and size (>20 nm) of AuNPs that were not cytotoxic on HaCat keratinocytes and 3T3 fibroblasts were determined. Both collagen sponges and AuNP-incorporated nanocomposites (CS-Au) were cross-linked with glutaraldehyde (CS-X and CS-AuX). Incorporation of AuNPs into cross-linked scaffolds enhanced their stability against enzymatic degradation and increased the tensile strength. Hydrolytic degradation of CS-Au group was also less than CS after seven days. Upon confirming in vitro biocompatibility of the scaffolds with cytotoxicity assays, cell attachment and proliferation tests and the in vivo efficacy for healing of full-thickness skin wounds were investigated by applying CS-X, CS-AuX or a commercial product (Matriderm®) onto defect sites and covering with Ioban® drapes. Defects were covered only with drapes for untreated control group. The wound areas were examined with histopathological and biomechanical tests after 14 days of operation. CS-AuX group was superior to untreated control and Matriderm®; it suppressed the inflammation while significantly promoting granulation tissue formation. Inflammatory reaction against CS-AuX was milder than CS-X. Neovascularization was also higher in CS-AuX than other groups, though the result was not significant. Wound closure in CS-X (76%), CS-AuX (69%), and Matriderm® (65%) were better than untreated control (45%). CS-AuX group had the highest tensile strength (significantly higher than Matriderm®) and modulus (significantly higher than Matriderm® and CS-X), indicating a faster course of dermal healing. Further studies are also needed to investigate whether higher loading of AuNPs affects these results positively in a statistically meaningful manner. Overall, their contribution to the enhancement of degradation profiles and mechanical properties, their excellent in vitro biocompatibility, and tendency to accelerate wound healing are encouraging the use of AuNPs in collagen sponges as potent skin substitutes in the future.

The effectiveness of a silk fibroin/gold nanoparticle 3D nanofibrous matrix on a rat model of full-thickness dermal wound healing was investigated.

As a novel approach in skin tissue engineering, gold nanoparticles (AuNPs) were synthesized and incorporated at different concentrations into collagen/PEO nanofibrous matrices in this study. The group containing 14.27 ppm AuNPs (CM-Au) had the best nanofibrous morphology. CM-Au was cross-linked with glutaraldehyde vapor (CM-AuX). All groups were disrupted in collagenase in 2 h, but cross-linked groups and Matriderm® resisted hydrolytic degradation for 7 and 14 days, respectively. Due to its small pores and dense structure, lower water swelling results (7.26 ± 2.62 g/g) were obtained for CM-AuX than Matriderm (17.51 ± 1.97 g/g). CM-Au and Matriderm had statistically similar tensile strength and elastic modulus, but elongation at break of CM-Au (over 100%) was significantly better than that of Matriderm. After cross-linking, tensile strength and elastic modulus of collagen matrix was further improved. AuNPs (37 and 42 nm) seemed to be nontoxic on 3T3 fibroblasts and keratinocytes for different time periods. CM-AuX scaffold extracts were also nontoxic for 3T3 fibroblasts and keratinocytes. The L929 cell attachment and proliferation on CM-AuX were comparable with Matriderm, indicating good in vitro biocompatibility. As a whole, collagen matrices incorporated with AuNPs are potential biomaterial candidates for skin tissue engineering.

Herein, an easy one‐pot synthesis method for gold nanoparticles (AuNPs), involving only gold salt and sericin extracted from silkworm cocoon in the presence of ultraviolet C (UVC) radiation, was developed. Nanoparticle formation was confirmed by characteristic surface plasmon resonance peaks at 520–540 nm wavelengths, and the influence of silk sericin on enhancing the colloidal stability of AuNPs was confirmed. Transmission electron microscopy examination showed the average size (<10 nm) and size distribution decreased significantly with higher sericin concentration. No antibacterial activity was observed on Gram‐positive Bacillus subtilis or Gram‐negative Escherichia coli for sole AuNPs (0.065–0.26 mg/ml), but the conjugation of AuNPs with streptomycin antibiotic decreased significantly the required minimum inhibitory concentration doses, as also confirmed with agar plating, Scanning Electron Microscopy and Atomic Force Microscopy analyses. Furthermore, sericin‐capped AuNPs showed high cell viabilities (>100%) and no sign of any detectable apoptosis or necrosis in 1‐day incubation. Also, high real‐time cell proliferation results of AuNPs competitive with positive control groups implied excellent in vitro biocompatibility. These results evidenced that sericin enhanced the colloidal stability of AuNPs and the biological activities of sericin‐capped AuNPs reported here could render them suitable nanoscale vehicles for biomedical applications.