title: Comparative Study on the Efficiency of the Photodynamic Inactivation of Candida albicans Using CdTe Quantum Dots, Zn(II) Porphyrin and Their Conjugates as Photosensitizers.
abstract: 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.
authors.affiliation: Pharmaceutical Sciences Department, Pernambuco Federal University, Recife 50670-901, Brazil. osnirviana@yahoo.com.br.
authors.forename: Osnir S
authors.initials: OS
authors.lastname: Viana
authors.affiliation: Center for Lasers and Applications, IPEN-CNEN-SP, São Paulo 05508-000, Brazil. marthasr@usp.br.
authors.forename: Martha S
authors.initials: MS
authors.lastname: Ribeiro
authors.affiliation: Center for Lasers and Applications, IPEN-CNEN-SP, São Paulo 05508-000, Brazil. andrea.ipen@gmail.com.
authors.forename: Andréa C D
authors.initials: AC
authors.lastname: Rodas
authors.affiliation: Chemistry Department, CCEN Universidade Federal da Paraiba, João Pessoa 58051-900, Brazil. jsreboucas@quimica.ufpb.br.
authors.forename: Júlio S
authors.initials: JS
authors.lastname: Rebouças
authors.affiliation: Biophysics and Radiobiology Department, Pernambuco Federal University, Recife 50670-901, Brazil. adriana.fontes.biofisica@gmail.com.
authors.forename: Adriana
authors.initials: A
authors.lastname: Fontes
authors.affiliation: Pharmaceutical Sciences Department, Pernambuco Federal University, Recife 50670-901, Brazil. beate_santos@yahoo.com.br.
authors.forename: Beate S
authors.initials: BS
authors.lastname: Santos
mesh_terms: D019187:Cadmium Compounds / Q000737:chemistry / Q000494:pharmacology*; D002176:Candida albicans / Q000187:drug effects*; D002177:Candidiasis / Q000188:drug therapy / Q000382:microbiology; D002470:Cell Survival / Q000187:drug effects; D006801:Humans; D008027:Light; D008665:Metalloporphyrins / Q000494:pharmacology*; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000494:pharmacology*; D045663:Quantum Dots / Q000008:administration & dosage* / Q000737:chemistry; D013691:Tellurium / Q000737:chemistry / Q000494:pharmacology*
chemical_list: D019187:Cadmium Compounds; D008665:Metalloporphyrins; D017319:Photosensitizing Agents; C017802:zinc hematoporphyrin; D013691:Tellurium; C028337:cadmium telluride
keywords: Candida albicans; Zn-porphyrins; fibroblasts; photodynamic inactivation; photodynamic therapy; quantum dots