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The synthesis of light-responsive nanocarriers (LRNs) with a variety of surface functional groups and/or ligands has been intensively explored for space-temporal controlled cargo release. LRNs have been designed on demand for photodynamic-, photothermal-, chemo-, and radiotherapy, protected delivery of bioactive molecules, such as smart drug delivery systems and for theranostic duties. LRNs trigger the release of cargo by a light stimulus. The idea of modifying LRNs with different moieties and ligands search for site-specific cargo delivery imparting stealth effects and/or eliciting specific cellular interactions to improve the nanosystems’ safety and efficacy. This work reviews photoresponsive polymeric nanocarriers and photo-stimulation mechanisms, surface chemistry to link ligands and characterization of the resultant nanosystems. It summarizes the interesting biomedical applications of functionalized photo-controlled nanocarriers, highlighting the current challenges and opportunities of such high-performance photo-triggered delivery systems.

RESUMO:Veneno de cobra continua a ser um problema importante de saúde em muitos países da América Latina. Apesar dos avanços na terapia antiveneno, os efeitos locais causados por fosfolipases A 2 miotóxica (PLA 2 ) presentes no veneno, ainda persistem. Em busca de alternativas para antagonizar a atividade da PLA 2 do veneno de Bothrops asper, foram selecionados 36 extratos pertencentes a dezessete famílias de plantas vasculares e briófitas. Uma inibição significativa da atividade enzimática de PLA 2 presente no veneno de B. asper foi observada em onze extratos. Além disso, a atividade antioxidante dos extratos foi avaliada. Os resultados evidenciaram uma correlação estatisticamente significativa entre os extratos com ação inibitória contra a PLA 2 e aqueles com atividade antioxidante. Também, a quantidade de fenóis foi avaliada e foi encontrada uma relação entre a atividade biológica e a presença dessas substâncias. Nove extratos foram testados contra uma fração do veneno rico em PLA 2 básica (Fx-V B. asper), resultando em um efeito inibitório na atividade desta fração da PLA 2 na faixa de 30-80%. Esta atividade foi apoiada pela inibição que esses extratos apresentaram na citotoxicidade causada pelo Fx-V B. asper sobre mioblastos C2C12 de músculo esquelético de murino. Os resultados podem indicar a minimização dos esforços na busca de inibidores da PLA 2 , com foco nas amostras com propriedades antioxidantes conhecidas.Unitermos: fosfolipase A 2 , veneno de cobra, Bothrops asper, extratos de plantas, antioxidantes, DPPH.ABSTRACT: Snakebite continues to be a significant health problem in many countries of Latin America. Even though, there has been an improvement in the antivenom therapy, the local effects caused by myotoxic phospholipases A 2 (PLA 2 ) present in the venoms, still persist. In search for alternatives to antagonize the PLA 2 activity of Bothrops asper's venom, 36 extracts belonging to seventeen families of vascular plants and bryophytes were screened. A significant inhibition of the enzymatic activity of PLA 2 present in B. asper's whole venom was seen in eleven of these extracts. In addition, the antioxidant activity of all the extracts was evaluated. The results evidenced a significant statistical correlation between extracts with an inhibitory effect against PLA 2 and those with an antioxidant activity. Moreover, the amount of phenols was quantified finding a relationship between the bioactivity and the presence of these compounds. Nine extracts were screened against a fraction of the venom rich in basic PLA 2 (Fx-V B. asper), exhibiting an inhibitory effect on PLA 2 activity of this fraction in a range of 30-80%. This activity was supported by the inhibition that these extracts presented on the cytotoxicity caused by Fx-V B. asper on murine skeletal muscle C2C12 myoblasts. The results obtained, could point to minimize efforts in the search of PLA 2 inhibitors by focusing in samples with known antioxidant properties.

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