title: CdTe quantum dots conjugated to concanavalin A as potential fluorescent molecular probes for saccharides detection in Candida albicans.
abstract: Semiconductor colloidal quantum dots (QDs) have been applied in biological analysis due to their unique optical properties and their versatility to be conjugated to biomolecules, such as lectins and antibodies, acquiring specificity to label a variety of targets. Concanavalin A (Con A) lectin binds specifically to α-d-mannose and α-d-glucose regions of saccharides that are usually expressed on membranes of mammalian cells and on cell walls of microbials. Candida albicans is the most common fungal opportunistic pathogen present in humans. Therefore, in this work, this fungus was chosen as a model for understanding cells and biofilm-forming organisms. Here, we report an efficient bioconjugation process to bind CdTe (Cadmium Telluride) QDs to Con A, and applied the bioconjugates to label saccharide structures on the cellular surface of C. albicans suspensions and biofilms. By accomplishing hemagglutination experiments and circular dichroism, we observed that the Con A structure and biochemical properties were preserved after the bioconjugation. Fluorescence microscopy images of yeasts and hyphae cells, as well as biofilms, incubated with QDs-(Con A) showed a bright orange fluorescence profile, indicating that the cell walls were specifically labeled. Furthermore, flow cytometry measurements confirmed that over 93% of the yeast cells were successfully labeled by QD-(Con A) complex. In contrast, non-conjugated QDs or QDs-(inhibited Con A) do not label any kind of biological system tested, indicating that the bioconjugation was specific and efficient. The staining pattern of the cells and biofilms demonstrate that QDs were effectively bioconjugated to Con A with specific labeling of saccharide-rich structures on C. albicans. Consequently, this work opens new possibilities to monitor glucose and mannose molecules through fluorescence techniques, which can help to optimize phototherapy protocols for this kind of fungus.
authors.affiliation: Departamento de Ciências Farmacêuticas, Universidade Federal de Pernambuco, Recife, PE, Brazil.
authors.forename: Denise P L A
authors.initials: DP
authors.lastname: Tenório
authors.affiliation: Laboratório de Imunopatologia Keizo Asami, Universidade Federal de Pernambuco, Recife, PE, Brazil.
authors.forename: Camila G
authors.initials: CG
authors.lastname: Andrade
authors.affiliation: Departamento de Biofísica e Radiobiologia, Universidade Federal de Pernambuco, Recife, PE, Brazil.
authors.forename: Paulo E
authors.initials: PE
authors.lastname: Cabral Filho
authors.affiliation: Centro de Lasers e Aplicações, IPEN-CNEN/SP, São Paulo, SP, Brazil.
authors.forename: Caetano P
authors.initials: CP
authors.lastname: Sabino
authors.affiliation: Centro de Lasers e Aplicações, IPEN-CNEN/SP, São Paulo, SP, Brazil.
authors.forename: Ilka T
authors.initials: IT
authors.lastname: Kato
authors.affiliation: Laboratório de Imunopatologia Keizo Asami, Universidade Federal de Pernambuco, Recife, PE, Brazil.
authors.forename: Luiz B
authors.initials: LB
authors.lastname: Carvalho
authors.affiliation: Departamento de Química Fundamental, Universidade Federal de Pernambuco, Recife, PE, Brazil.
authors.forename: Severino
authors.initials: S
authors.lastname: Alves
authors.affiliation: Centro de Lasers e Aplicações, IPEN-CNEN/SP, São Paulo, SP, Brazil.
authors.forename: Martha S
authors.initials: MS
authors.lastname: Ribeiro
authors.affiliation: Departamento de Biofísica e Radiobiologia, Universidade Federal de Pernambuco, Recife, PE, Brazil. Electronic address: adriana.fontes.biofisica@gmail.com.
authors.forename: Adriana
authors.initials: A
authors.lastname: Fontes
authors.affiliation: Departamento de Ciências Farmacêuticas, Universidade Federal de Pernambuco, Recife, PE, Brazil. Electronic address: beate_santos@yahoo.com.br.
authors.forename: Beate S
authors.initials: BS
authors.lastname: Santos
mesh_terms: D019187:Cadmium Compounds / Q000737:chemistry; D002176:Candida albicans / Q000378:metabolism*; D003208:Concanavalin A / Q000737:chemistry* / Q000378:metabolism; D005456:Fluorescent Dyes / Q000737:chemistry*; D005947:Glucose / Q000032:analysis*; D008358:Mannose / Q000032:analysis*; D008856:Microscopy, Fluorescence; D045663:Quantum Dots / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D013691:Tellurium / Q000737:chemistry; D013870:Thiomalates / Q000737:chemistry
chemical_list: D019187:Cadmium Compounds; D005456:Fluorescent Dyes; D013870:Thiomalates; D003208:Concanavalin A; C046062:2-thiomalic acid; D005947:Glucose; D013691:Tellurium; D008358:Mannose; C028337:cadmium telluride