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Comprehensive study of interaction between biocompatible PEG‐InP/ZnS QDs and bovine serum albumin
Author(s) -
Sannaikar M. S.,
Inamdar Laxmi S.,
Pujar G. H.,
Wari M. N.,
Balasinor Nafisa H.,
Inamdar S. R.
Publication year - 2018
Publication title -
luminescence
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.428
H-Index - 45
eISSN - 1522-7243
pISSN - 1522-7235
DOI - 10.1002/bio.3438
Subject(s) - bovine serum albumin , quantum dot , chemistry , förster resonance energy transfer , polyethylene glycol , quenching (fluorescence) , peg ratio , fluorescence , photochemistry , photoluminescence , analytical chemistry (journal) , materials science , nanotechnology , chromatography , organic chemistry , physics , optoelectronics , finance , quantum mechanics , economics
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.