Comprehensive study of interaction between biocompatible PEG‐InP/ZnS QDs and bovine serum albumin. (28th December 2017)

• Record Type: Journal Article
• Authors: Sannaikar, M. S.; Inamdar, Laxmi S.; Pujar, G. H.; Wari, M. N.; Balasinor, Nafisa H.; Inamdar, S. R.
• Is Part Of: Luminescence. Volume 33:Number 3(2018)
• Page Start: 495
• Page End: 504
• Publication Date: 2017-12-28
• Subjects: bioconjugation -- BSA -- FRET -- Hill coefficient -- PEG‐InP/ZnS QDs; Luminescence -- Periodicals; Bioluminescence -- Periodicals; Chemiluminescence -- Periodicals; Luminescence -- Periodicals; 535.35
• DOI: 10.1002/bio.3438
• Languages: English
• ISSNs: 1522-7235

Abstract

Abstract: Polyethylene glycol (PEG) surface modified biocompatible InP/ZnS quantum dots (QDs) act as a potential alternative for conventional carcinogenic cadmium‐based quantum dots for in vivo and in vitro studies. Comprehensively, we studied the interaction between a model protein bovine serum albumin (BSA) and PEGylated toxic free InP/ZnS QDs using various spectroscopic tools such as absorption, fluorescence quenching, time resolved and synchronous fluorescence spectroscopic measurements. These studies principally show that tryptophan ( Trp ) residues of BSA have preferable binding affinity towards PEG‐InP/ZnS QDs surface and a blue shift in Trp fluorescence emission is a signature of conformational changes in its hydrophobic microenvironment. Photoluminescence (PL) intensity of Trp is quenched by ground state complex formation (static quenching) at room temperature. However, InP/ZnS@BSA conjugates become unstable with increasing temperature and PL intensity of Trp is quenched via dynamic quenching by PEG‐InP/ZnS QDs. Experimentally determined thermodynamic parameters for these conjugates have shown spontaneity, entropy driven and exothermic nature of bio‐conjugation. The calculated binding affinity ( n ≅ 1, Hill coefficient) suggest that the affinity of InP/ZnS QDs for a BSA protein is not dependent on whether or not other BSA proteins are already bound to the QD surface. Energy transfer efficiency ( E ), Trp residue to InP/ZnS QDs distances and energy transfer rate ( k T ) were all obtained from FÖrster resonance energy.