title: Mn-doped zinc sulphide nanocrystals for immunofluorescent labeling of epidermal growth factor receptors on cells and clinical tumor tissues.
abstract: The field of molecular detection and targeted imaging has evolved considerably with the introduction of fluorescent semiconductor nanocrystals. Manganese-doped zinc sulphide nanocrystals (ZnS:Mn NCs), which are widely used in electroluminescent displays, have been explored for the first time for direct immunofluorescent (IF) labeling of clinical tumor tissues. ZnS:Mn NCs developed through a facile wet chemistry route were capped using amino acid cysteine, conjugated to streptavidin and thereafter coupled to biotinylated epidermal growth factor receptor (EGFR) antibody utilizing the streptavidin-biotin linkage. The overall conjugation yielded stable EGFR antibody conjugated ZnS:Mn NCs (EGFR ZnS:Mn NCs) with a hydrodynamic diameter of 65 ± 15 nm, and having an intense orange-red fluorescence emission at 598 nm. Specific labeling of EGF receptors on EGFR(+ve) A431 cells in a co-culture with EGFR(-ve) NIH3T3 cells was demonstrated using these nanoprobes. The primary antibody conjugated fluorescent NCs could also clearly delineate EGFR over-expressing cells on clinical tumor tissues processed by formalin fixation as well as cryopreservation with a specificity of 86% and accuracy of 88%, in comparison to immunohistochemistry. Tumor tissues labeled with EGFR ZnS:Mn NCs showed good fluorescence emission when imaged after storage even at 15 months. Thus, ZnS nanobioconjugates with dopant-dependent and stable fluorescence emission show promise as an efficient, target-specific fluorophore that would enable long term IF labeling of any antigen of interest on clinical tissues.
authors.affiliation: Amrita Center for Nanosciences and Molecular Medicine, Amrita Vishwa Vidyapeetham University, Cochin, 682 041 Kerala, India.
authors.forename: J
authors.initials: J
authors.lastname: Aswathy
authors.forename: N V
authors.initials: NV
authors.lastname: Seethalekshmy
authors.forename: K R
authors.initials: KR
authors.lastname: Hiran
authors.forename: M R
authors.initials: MR
authors.lastname: Bindhu
authors.forename: K
authors.initials: K
authors.lastname: Manzoor
authors.forename: Shantikumar V
authors.initials: SV
authors.lastname: Nair
authors.forename: Deepthy
authors.initials: D
authors.lastname: Menon
mesh_terms: D045744:Cell Line, Tumor; D066246:ErbB Receptors / Q000032:analysis*; D005455:Fluorescent Antibody Technique / Q000379:methods*; D005910:Glioma / Q000378:metabolism*; D006801:Humans; D008345:Manganese / Q000737:chemistry; D009062:Mouth Neoplasms / Q000378:metabolism*; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D012878:Skin Neoplasms / Q000378:metabolism*; D013440:Sulfides / Q000737:chemistry; D017967:Zinc Compounds / Q000737:chemistry
chemical_list: D013440:Sulfides; D017967:Zinc Compounds; D008345:Manganese; D066246:ErbB Receptors; C031238:zinc sulfide