**7. Engineered scaffolds and nanocomposites for wound healing**

One most important feature of the modern dressings used for the therapeutic purpose for skin tissue repair involves the designing of engineered biocompatible nanoscaffolds to mimic the structure of ECM (**Figures 2** and **3**). Such nanoscaffolds should possess the properties such as porous nature, biocompatibility, tendency to incorporate and release various growth factors/antibiotics in a controlled manner, and support for the attachment of cells and their proliferation [158]. Scaffold-based tissueengineered nanocomposites have been known to accelerate chronic wound healing by improvement in angiogenesis [159]. Various nanotechnology-based methods such as electrospinning, phase separation, and self-assembly have been devised for the formation of such scaffolds [65]. Electrospinning is the most favored method among all these methods for the preparation of nanofibrous scaffolds for skin tissue engineering [160]. For promoting diabetic wound healing and increasing collagen content, nanofibrous glucophage-loaded collagen/PLGA scaffolds were fabricated by electrospinning [161]. In another study, electrospun PCL scaffolds resulted in fibroblast attachment and proliferation. Full-thickness skin wounds of guinea pigs healed within 35 days after treatment with these membranes [162]. Similarly, electrospun membrane of PCL/chitosan nanofibers/aloe vera was fabricated to mimic both the

#### *Nanotechnological Interventions and Mechanistic Insights into Wound-Healing Events DOI: http://dx.doi.org/10.5772/intechopen.106481*

layers of skin. Top dense layer was composed of PCL to provide mechanical strength to the wounded site, and bottom layer of the dressing consisted of chitosan nanofibers and aloe vera to provide bactericidal activity for promoting skin wound healing [163]. Electrospun chitosan-poly(ethylene oxide) (PEO) nanofibrous scaffold-incorporated PLGA NPs were studied for *in vivo* wound healing [164]. In another report, chitosan NPs and TiO2 NPs were incorporated in polyurethane nanocomposites membranes, which showed 71.5% improvement in swelling when compared to neat polyurethane membrane and resulted in increase in tensile strength and antibacterial activity suitable for wound healing [165]. Multilayer wound dressing prepared by electrospun polyurethane nanofibers loaded with Semellil extract and other layer chitosan nanofiber resulted in 94% wound closure after 14 days [166].

Another material, that is, nanocomposites have also been proved beneficial for wound healing due to the properties possessed by its dispersed phase and reinforcing fillers. The nanocomposites serve as optimum wound dressing materials as they provide better mechanical strength due to the synergistic action of both the components. In a study, nanocomposites of collagen sponges and AuNPs showed greater tensile strength and indicated a faster wound healing [167]. In a different report, cerium nanocrystals were immobilized onto mesoporous silica NPs to develop ROS scavenging nanocomposites for wound healing. Ceria nanocrystals are known to reduce ROS and to protect the cell from oxidative damage. Silica NPs act as nanobridge between nanomaterial and tissue matrix for rapid wound closure. The nanocomposite prepared from both the components resulted in accelerated wound healing due to their synergistic action [168]. Another type of nanocomposites was prepared by using bacterial cellulose and hyaluronic acid. Bacterial cellulose has high-water-absorbing capacity and porous nature responsible for enhancing the wound-healing rate, whereas hyaluronic acid is biocompatible and possesses gel-forming capacity. The developed nanocomposites facilitated the growth of fibroblast cells and promoted the tissue repair [169]. Nanocomposites wound dressing for chronic wounds prepared from halloysite and chitosan oligosaccharides showed better skin re-epithelization and reorganization as compared to halloysite or chitosan alone [170].
