Surface functionalization of quantum dots for biological applications

•This review provides a comprehensive study over methods for surface modification of quantum dots.•Need for surface modification of quantum dots with special concern with biological applications.•Functionalization chemistry for attaching biomolecules such as DNA, peptides, proteins and antibodies.•Adsorption and covalent coupling of biomolecules such as amide coupling, thiol bonding and click chemistry.•Major limitations of use of quantum dots in biomedical applications.

Quantum dots are a group of inorganic nanomaterials exhibiting exceptional optical and electronic properties which impart distinct advantages over traditional fluorescent organic dyes in terms of tunable broad excitation and narrow emission spectra, signal brightness, high quantum yield and photo-stability. Aqueous solubility and surface functionalization are the most common problems for QDs employed in biological research. This review addresses the recent research progress made to improve aqueous solubility, functionalization of biomolecules to QD surface and the poorly understood chemistry involved in the steps of bio-functionalization of such nanoparticles.

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