Silva, JoãoVideira, PaulaLagoa, Ricardo2017-04-122017-04-122017J. Silva, P. Videira and R. Lagoa, "Bioactivity gradients of cytoprotective and anticancer catechins in skin: Simulation studies for the design of controlled release systems," 2017 IEEE 5th Portuguese Meeting on Bioengineering (ENBENG), Coimbra, Portugal, 2017, pp. 1-4.http://hdl.handle.net/10400.8/2554Conference paper (selected oral communication)Dermal delivery of catechins may be an effective approach for protection of skin against inflammation, aging and cancer caused by exposure to radiation and environmental toxicants. Catechins are flavonoid-type polyphenols showing capacity to attenuate UV-induced skin injury, carcinogenesis and melanoma metastasis, but the prevalence of beneficial effects depends on compound concentration. In this work, catechin penetration through the skin was simulated to predict the concentration in different layers: stratum corneum, viable epidermis and dermis. By combining these results with expected dose-effect relationships of the compounds, bioactivity profiles were calculated for relevant skin regions. Since the concentration dependences of catechin capacities to protect dermal fibroblasts and to inhibit melanoma cells (data aggregated from published literature) follow different types of dose-effect curves, bioactivity profiles in the skin can be different, even for the same delivery conditions. This method allows to estimate the delivery conditions (time and concentrations) required to achieve the desired biological/pharmacological activities at critical skin strata, namely, viable epidermis and dermis where metastatic melanoma cells and susceptible fibroblasts localize. The work suggests a framework to support the rational design of controlled release systems of topically applied bioactive compounds in therapeutic and investigative delivery.engResearch Subject Categories::TECHNOLOGY::BioengineeringBiomedical engineeringBiological system modelingMalignant tumorsDiffusion modelResearch Subject Categories::NATURAL SCIENCES::Chemistry::BiochemistryResearch Subject Categories::MEDICINE::Morphology, cell biology, pathology::Morphology::Biomaterialsjournal article10.1109/ENBENG.2017.7889467