Effects and formulation of silver nanoscaffolds on cytotoxicity dependent ion release kinetics towards enhanced excision wound healing patterns in Wistar albino rats

Abstract

Wound tissue regeneration and angiogenesis are dynamic processes that send physiological signals to the body. Thus, designing novel nanoscaffolds by understanding their surface modifications and toxicological response in a biological system with a potent anti-inflammatory response is a viable solution. In this respect, inspired by the surface chemistry, in the present work we focus on the chemical optimization of silver nanoscaffolds using surface cappings in order to understand their kinetic release behaviour in simulated wound fluids (SWF), to analyze their blood compatibility in human lymphocytes and erythrocytes and then embed them in a chitosan-agarose matrix (CAM) as a productive drug delivery system to evaluate in vivo excision wound tissue regeneration efficiency in Wistar rats. In this regard, polyvinyl alcohol capped silver nanocomposites (PVA-AgNPs) exhibit a dominant antibacterial efficacy with the sustained and controlled release of silver ions and percentage cell mortality and percentage hemolysis of only 10% and 16% compared with uncapped-AgNPs or silver bandaids (SBDs). Also, PVA-AgNP impregnated CAM (PVA-CAM) shows positive effects through their anti-inflammatory and angiogenic properties, with a nearly 95% healing effect within 9 days. The complete development of collagen and fibroblast constituents was also monitored in PVA-CAM by hematoxylin & eosin (H & E) and Masson trichrome (MT) staining. These results provide a clear insight into the development of a potent therapeutic formulation using CAM as a scaffold incorporated with surface functionalized PVA-AgNPs as a bioeffective and biocompatible polymer for the fabrication of efficacious silver wound dressing scaffolds in clinical practice.

Fig. 1. Characterization of chemically synthesized AgNPs using various capping agents. (1a–1e) Determination of particle core size using transmission electron microscopy (TEM) for the AgNPs. (2a–2e) Surface morphological features of AgNPs impregnated onto cotton fabrics using scanning electron microscopy (SEM). (3a–3e) Presence of elemental silver detected by energy dispersive X-ray spectroscopy (EDS) for the AgNPs. (4a–4e) Determination of functional groups using Fourier transform infrared (FTIR) spectroscopy for the AgNPs. Uncapped-AgNPs (1a, 2a, 3a and 4a), TSC-AgNPs (1b, 2b, 3b and 4b), PVP-AgNPs (1c, 2c, 3c and 4c), PVA-AgNPs (1d, 2d, 3d and 4d), SBD-suspension (1e, 2e, 3e and 4e). * represents the presence of capping agents on the surface of nanoparticles, + represents the presence of AgNPs and to denote where the EDS was taken.

Fig. 2. Silver ion release kinetics of AgNPs using different capping agents.

Fig. 3. Cell mortality rate of WBCs interacted with different AgNP formulations.

Fig. 4. Hemolytic activity of AgNPs using different capping agents.

Fig. 5. Wound healing efficiency of different CAM associated AgNP formulations during the 3^rd day, 9^th day, 14^th day and 20^th days. Healing period with respect to number of days: (1a–1e) control group, (2a–2e) CAM, (3a–3e) uncapped-CAM, (4a–4e) TSC-CAM, (5a–5e) PVP-CAM, (6a–6e) PVA-CAM, (7a–7e) SBD-CAM.

Fig. 6. Percentage of wound contraction of CAM associated AgNP formulations.

Fig. 7. Histopathological observations of wounds after treatment with CAM associated AgNP formulations. Red arrows represent the development of collagen and fibroblast regeneration tissues stained using hematoxylin & eosin (H & E). Control group (1a and 2a), CAM (1b and 2b), uncapped-CAM (1c and 2c), TSC-CAM (1d and 2d), PVP-CAM (1e and 2e), PVA-CAM (1f and 2f), SBD-CAM (1g and 2g). (1 represents 9^th day, 2 represents 14^th day).

Fig. 8. Histopathological observations of CAM associated AgNP treated wounds using Masson trichrome (MT) staining. Red arrows represent the maximum growth of collagen fibers and fibrin regenerative tissues. Control group (1a and 2a), CAM (1b and 2b), uncapped-CAM (1c and 2c), TSC-CAM (1d and 2d), PVP-CAM (1e and 2e), PVA-CAM (1f and 2f), SBD-CAM (1g and 2g) (1 represents 9^th day, 2 represents 14^th day).