Viana Osnir S, Ribeiro Martha S, Rodas Andréa C D, Rebouças Júlio S, Fontes Adriana, Santos Beate S
Pharmaceutical Sciences Department, Pernambuco Federal University, Recife 50670-901, Brazil.
Center for Lasers and Applications, IPEN-CNEN-SP, São Paulo 05508-000, Brazil.
Molecules. 2015 May 18;20(5):8893-912. doi: 10.3390/molecules20058893.
The application of fluorescent II-VI semiconductor quantum dots (QDs) as active photosensitizers in photodymanic inactivation (PDI) is still being evaluated. In the present study, we prepared 3 nm size CdTe QDs coated with mercaptosuccinic acid and conjugated them electrostatically with Zn(II) meso-tetrakis (N-ethyl-2-pyridinium-2-yl) porphyrin (ZnTE-2-PyP or ZnP), thus producing QDs-ZnP conjugates. We evaluated the capability of the systems, bare QDs and conjugates, to produce reactive oxygen species (ROS) and applied them in photodynamic inactivation in cultures of Candida albicans by irradiating the QDs and testing the hypothesis of a possible combined contribution of the PDI action. Tests of in vitro cytotoxicity and phototoxicity in fibroblasts were also performed in the presence and absence of light irradiation. The overall results showed an efficient ROS production for all tested systems and a low cytotoxicity (cell viability >90%) in the absence of radiation. Fibroblasts incubated with the QDs-ZnP and subjected to irradiation showed a higher cytotoxicity (cell viability <90%) depending on QD concentration compared to the bare groups. The PDI effects of bare CdTe QD on Candida albicans demonstrated a lower reduction of the cell viability (1 log10) compared to bare ZnP which showed a high microbicidal activity (3 log10) when photoactivated. The QD-ZnP conjugates also showed reduced photodynamic activity against C. albicans compared to bare ZnP and we suggest that the conjugation with QDs prevents the transmembrane cellular uptake of the ZnP molecules, reducing their photoactivity.
荧光II-VI族半导体量子点（QDs）作为光动力失活（PDI）中的活性光敏剂的应用仍在评估中。在本研究中，我们制备了包覆巯基琥珀酸的3纳米大小的碲化镉量子点，并将它们与锌（II）中-四（N-乙基-2-吡啶基）卟啉（ZnTE-2-PyP或ZnP）进行静电共轭，从而制备出量子点-锌卟啉共轭物。我们评估了量子点、共轭物以及裸露量子点体系产生活性氧（ROS）的能力，并通过照射量子点将它们应用于白色念珠菌培养物的光动力失活中，同时检验PDI作用可能存在的联合贡献这一假设。还在有光照射和无光照射的情况下对成纤维细胞进行了体外细胞毒性和光毒性测试。总体结果表明，所有测试体系都能高效产生活性氧，且在无辐射时细胞毒性较低（细胞活力>90%）。与裸露组相比，用量子点-锌卟啉共轭物处理并接受照射的成纤维细胞，根据量子点浓度不同，显示出更高的细胞毒性（细胞活力<90%）。裸露的碲化镉量子点对白色念珠菌的PDI效应表明，与裸露的锌卟啉相比，其对细胞活力的降低程度较低（约1个对数级），而裸露的锌卟啉光激活后具有较高的杀菌活性（约3个对数级）。与裸露的锌卟啉相比，量子点-锌卟啉共轭物对白色念珠菌的光动力活性也有所降低，我们认为与量子点的共轭作用会阻止锌卟啉分子跨膜进入细胞，从而降低其光活性。
