# State-of-All-the-Art and Prospective Hydrogel-Based Transdermal Drug Delivery Systems
## 6 Some Important Applications of Hydrogels in Transdermal Drug Delivery Systems
### Wound Management  
A wound is any disturbance or breakage in the skin that arises from a medical condition, physiological issue, or trauma. When injured or wounded tissue returns to its pre-injury or normal anatomical appearance, structure, and function within an acceptable time frame, the wound is considered totally healed [6]. The process of wound healing is continuous and comprises four distinct, automatic phases. Every phase needs to be controlled precisely and in a certain way. Any disruption or extension of these stages could result in a longer healing period for the wound and increase the chance that it will become a chronic wound. Hydrogels are best suited for burn patients since they possess most of the ideal characteristics anticipated for wound healing. Healthcare professionals and biomaterial scientists acknowledge hydrogels as the preferred choice for wound dressing due to their numerous advantages. These include maintaining optimal moisture levels at the wound site, facilitating proper exchange of oxygen and moisture between the wound and its surroundings, biocompatibility, possessing a structure resembling tissue, ease of application owing to softness, elasticity, and flexibility, offering a cooling sensation for patient comfort, absorbing serous discharges from lesions, and minimizing interference with the wound healing process [77]. Various hydrogels used in wound dressing and healing include composite formulations like gelatin-grafted dopamine/chitosan/carbon nanotubes, lignin-chitosan-PVA, and nano curcumin-loaded N, O-carboxymethyl chitosan/oxidized alginate hydrogel [77]. Calcium alginate hydrogel dressings derived from a foundation are another potential form of wound dressing used for treating highly exudative wounds, as they promote the growth of granulation tissue. The interaction between salt from wounds and alginate, forming a gel structure, establishes an optimal moist healing environment. Calcium further facilitatescell migration, remodeling, and wound homeostasis [77]. In the literature, there are several types of hydrogels used for wound management. (Tables 5 and 6). \begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline
**Gel Type** & **Therapeutic/Drug** & **Application** & **Results** & **Reference** \\ \hline Hydrogel Forming & Ibuprofen Sodium & Clinically relevant non-potent drug delivery &  
\begin{table}
\begin{tabular}{l l l l l} \hline
**Gel Type** & **Therapeutic/Drug** & **Application** & **Results** & **Reference** \\ \hline \multirow{9}{*}{Hydrogel Micronneedle Patch} & \multirow{3}{*}{Doxorubicinchloride (Dox)} & \multirow{3}{*}{Controlled drug release} & \multirow{3}{*}{*} & The first methacylated hyaluronic acid (MeHA) on M.N. patches is & \\  & & & & showcased as a drug carrier for & \\  & & & & diverse therapeutics. & \\  & & & & \(\bullet\) & Exhibit high swelling in aqueous & \\  & & & & solutions, enabling the efficient and & \\  & & & & effective loading of molecules of & \\  & & & & diverse sizes. & \\  & & & & \(\bullet\) & Loaded drugs exhibited & \\  & & & & mechanical robustness to penetrate & \\  & & & & the stratum corneum. & \\  & & & & \(\bullet\) & High adhesion strength. \\ \hline \multirow{9}{*}{Adhesive Composite Hydrogel} & \multirow{3}{*}{Dexamethasone (DEX)} & \multirow{3}{*}{Atopic dermatitis (A.D.)} & \multirow{3}{*}{It exhibits a high water content and strong adhesion to porcine skin. A sustained release of drug when loaded within the pores of XL-MSNs in PAM/PDA hydrogels. Application of DEX-loaded hydrogels on an A.D. mouse model led to the significant suppression of A.D. symptoms.} & \multirow{3}{*}{Developed hydrogel possesses outstanding autonomous healing capabilities and the ability to dissolve or remove on-demand. Demonstrates injectable, favorable biocompatibility, antibacterial activity, multifunctional adhesiveness, hemostatic properties, and responsiveness to near-infrared (NIR). In vivo assessment showed significant effectiveness in wound closure, with successful post-wound closure outcomes.}