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One-step colloidal synthesis of biocompatible water-soluble ZnS quantum dot/chitosan nanoconjugates

Fábio P Ramanery, Alexandra AP Mansur and Herman S Mansur*

Author Affiliations

Center of Nanoscience, Nanotechnology and Innovation - CeNano2I, Department of Metallurgical and Materials Engineering, Escola de Engenharia, Federal University of Minas Gerais, Bloco 2, Sala 2233, Av. Antônio Carlos, 6627, Belo Horizonte, Minas Gerais 31270-901, Brazil

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Nanoscale Research Letters 2013, 8:512  doi:10.1186/1556-276X-8-512

Published: 5 December 2013

Abstract

Quantum dots (QDs) are luminescent semiconductor nanocrystals with great prospective for use in biomedical and environmental applications. Nonetheless, eliminating the potential cytotoxicity of the QDs made with heavy metals is still a challenge facing the research community. Thus, the aim of this work was to develop a novel facile route for synthesising biocompatible QDs employing carbohydrate ligands in aqueous colloidal chemistry with optical properties tuned by pH. The synthesis of ZnS QDs capped by chitosan was performed using a single-step aqueous colloidal process at room temperature. The nanobioconjugates were extensively characterised by several techniques, and the results demonstrated that the average size of ZnS nanocrystals and their fluorescent properties were influenced by the pH during the synthesis. Hence, novel 'cadmium-free’ biofunctionalised systems based on ZnS QDs capped by chitosan were successfully developed exhibiting luminescent activity that may be used in a large number of possible applications, such as probes in biology, medicine and pharmacy.

Keywords:
Nanoparticle; Quantum dot; Colloid; Biopolymer; Chitosan; Bioconjugates; Nanomaterials; 81.07.Ta; 78.67.Hc; 78.67.Sc; 82.35.Pq