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Transdermal Drug Delivery
Published in Emmanuel Opara, Controlled Drug Delivery Systems, 2020
Brahmeshwar Mishra, Gunjan Vasant Bonde
Below the epidermis is the 3–5 mm thick dermis. It is a highly vascular structure consisting of connective tissues with collagen and elastin fibers as the extracellular matrix, lymphatic vessels, and nerve endings. It hosts various skin appendages such as sebaceous and sweats glands as well as hair follicles, etc. (Montenegro et al. 2016). Also, it is associated with homeostasis functions regulating body temperature, nutrients, and oxygen supply to the skin and excreting toxic waste. The fibroblasts and macrophages also reside in the dermis and are responsible for the synthesis as well as the renewal of extracellular matrix and immune defense against invading foreign material, respectively. The extensive blood capillary beds serve as the first site of systemic access to drug molecules (Wong 2014, Abd et al. 2016).
Fabrication and evaluation of hesperidin loaded polyacrylonitrile/polyethylene oxide nanofibers for wound dressing application
Published in Journal of Biomaterials Science, Polymer Edition, 2021
Somayeh Taymouri, Saeed Hashemi, Jaleh Varshosaz, Mohsen Minaiyan, Ardeshir Talebi
H&E staining was performed on the sectioned tissue samples of the wound site to monitor the tissue microarchitecture. The results are shown in Figure 9. Histological evaluation on day 5 showed that the wounds treated with HPN loaded nanofibers had less inflammatory cells, congestion and edema, as compared with HPN-free nanofibers and normal saline groups. On this day, re-epithelialization, angiogenesis and connective tissue formation were observable in all specimens. However, wounds treated with HPN loaded nanofibers exhibited more re-epithelialization than the other two groups. In addition, the regeneration of appendages was seen in the specimens treated with the HPN loaded nanofibers, which was not observed in the other groups at all. On the day 9 of the study, inflammation, edema and congestion were not observed in the wounds treated with nanofibers with and without HPN. However, the inflammatory cells were still found in the wounds skin section of the normal saline group. HPN loaded nanofiber facilitated more skin appendage formation and re-epithelialization when compared with other groups. Masson’s trichrome stained sections were used for the collagen formation assay (Figure 9). The results showed that on both days 5 and 9, collagen reproduced in the wounds covered with HPN loaded nanofibers was denser and more aligned than that in the wound treated with normal saline and the HPN-free nanofiber. It is noteworthy that HPN-free nanofibers increased the content of the collagen tissue, reepithelization and appendage formation when compared with the normal saline. This is because HPN-free nanofibers could create a structural support for cell attachment, growth and migration on the wound region [17,41]. Overall, HPN loaded nanofibers showed potentials for wound repair application, which could be related to the function of nanofibers as the native extracellular matrix, together with the bioactivity of HPN.