A short review on chitosan and gelatin-based hydrogel composite polymers for wound healing.

This review focuses on the modification of chitosan and gelatin-based hydrogel composite polymers for wound healing. First, the mechanical properties of several nanocomposite polymer hydrogels are compared based on water content, tensile strength, toughness and tensile strain. Furthermore, key findings on several modification techniques of the mechanical properties of chitosan are summarized. For example, we show that complexation of iron ions improves mechanical properties better than most other metal ions. Subsequently, gelatin - based hydrogel polymeric systems are compared on the basis of their preparative techniques, time to hemostasis, in vivo model and wound type, blood loss in treatment groups, biocompatibility and adhesive strength. Next, major outcomes on several techniques for improving the mechanical properties of gelatin biopolymer for wound healing are discussed. Then, effects of crosslinking on mechanical properties and hydrogel biocompatibility, in particular, the relationship between DHT crosslinking and gelation concentration are presented. Finally, research on adhesive anti-biofilm hydrogels are summarized, with focus on bacterial cellulosic, and chitosan - based hydrogels. Though similar reviews have been presented, the role of specific biological macromolecule-based composites such as chitosan and gelatin, have not been reviewed for some time despite the abundance of primary research findings. Knowledge gap and a list of unaddressed research questions are presented to aid further work in the field.

Microneedle-Based Natural Polysaccharide for Drug Delivery Systems (DDS): Progress and Challenges.

In this focused progress review, the most widely accepted methods of transdermal drug delivery are hypodermic needles, transdermal patches and topical creams. However, microneedles (MNs) (or microneedle arrays) are low-invasive 3D biomedical constructs that bypass the skin barrier and produce systemic and localized pharmacological effects. In the past, biomaterials such as carbohydrates, due to their physicochemical properties, have been extensively used to manufacture microneedles (MNs). Due to their wide range of functional groups, carbohydrates enable the design and development of tunable properties and functionalities. In recent years, numerous microneedle products have emerged on the market, although much research needs to be undertaken to overcome the various challenges before the successful introduction of microneedles into the market. As a result, carbohydrate-based microarrays have a high potential to achieve a future step in sensing, drug delivery, and biologics restitution. In this review, a comprehensive overview of carbohydrates such as hyaluronic acid, chitin, chitosan, chondroitin sulfate, cellulose and starch is discussed systematically. It also discusses the various drug delivery strategies and mechanical properties of biomaterial-based MNs, the progress made so far in the clinical translation of carbohydrate-based MNs, and the promotional opportunities for their commercialization. In conclusion, the article summarizes the future perspectives of carbohydrate-based MNs, which are considered as the new class of topical drug delivery systems.

Natural Polymeric Scaffolds for Tissue Engineering Applications.

Natural polymeric scaffolds can be used for tissue engineering applications such as cell delivery and cell-free supporting of native tissues. This is because of their desirable properties such as; high biocompatibility, tunable mechanical strength and conductivity, large surface area, porous- and extracellular matrix (ECM)-mimicked structures. Specifically, their less toxicity and biocompatibility makes them suitable for several tissue engineering applications. For these reasons, several biopolymeric scaffolds are currently being explored for numerous tissue engineering applications. To date, research on the nature, chemistry, and properties of nanocomposite biopolymers are been reported, while the need for a comprehensive research note on more tissue engineering application of these biopolymers remains. As a result, this present study comprehensively reviews the development of common natural biopolymers as scaffolds for tissue engineering applications such as cartilage tissue engineering, cornea repairs, osteochondral defect repairs, and nerve regeneration. More so, the implications of research findings for further studies are presented, while the impact of research advances on future research and other specific recommendations are added as well.