Title
Interaction of insulin with colloidal ZnS quantum dots functionalized by various surface capping agents
Author
Ghader Hosseinzadeh, Ali Maghari, Seyed Morteza Famil Farniya, Amir Homayoun Keihan, Ali A. Moosavi-Movahedi
Year
2017
Journal
Materials Science and Engineering: C
Abstract
Interaction of quantum dots (QDs) and proteins strongly influenced by the surface characteristics of the QDs at the protein-QD interface. For a precise control of these surface-related interactions, it is necessary to improve our understanding in this field. In this regard, in the present work, the interaction between the insulin and differently functionalized ZnS quantum dots (QDs) were studied. The ZnS QDs were functionalized with various functional groups of hydroxyl (single bondOH), carboxyl (single bondCOOH), amine (single bondNH2), and amino acid (single bondCOOH and single bondNH2). The effect of surface hydrophobicity was also studied by changing the alkyl-chain lengths of mercaptocarboxylic acid capping agents. The interaction between insulin and the ZnS QDs were investigated by fluorescence quenching, synchronous fluorescence, circular dichroism (CD), and thermal aggregation techniques. The results reveal that among the studied QDs, mercaptosuccinic acid functionalized QDs has the strongest interaction (∆ G° = − 51.50 kJ/mol at 310 K) with insulin, mercaptoethanol functionalized QDs destabilize insulin by increasing the beta-sheet contents, and only cysteine functionalized QDs improves the insulin stability by increasing the alpha-helix contents of the protein, and. Our results also indicate that by increasing the alkyl-chain length of capping agents, due to an increase in hydrophobicity of the QDs surface, the beta-sheet contents of insulin increase which results in the enhancement of insulin instability.
Instrument
J-810
Keywords
Circular dichroism, Secondary structure, Chemical stability, Materials, Biochemistry