Effect of CdS QDs linked functional groups on interaction between CdS QDs and EcoRI

In this study, we investigated the interaction between EcoRI and CdS QDs modified with different functional groups as well as the conformational changes of EcoRI in the process. MUD capped (CdS-OH QDs) and UDT capped (CdS-CH3 QDs) CdS QDs were separately prepared and used to react with EcoRI, respectively. The interaction was characterized by various spectroscopic techniques including UV-vis absorption, fluorescence and Fourier transform infrared (FTIR) spectroscopy, together with electrophoresis methods. The strength of interaction for EcoRI with CdS-OH QDs and CdS-CH3 QDs was evaluated and analysed. Relevant thermodynamic parameters such as Delta H, Delta G and Delta S were calculated and a static quenching interaction process was proposed. The conformational change of EcoRI interacted with CdS-OH QDs or CdS-CH3 QDs was also measured and compared. Finally agarose electrophoresis assay was performed and revealed that the enzyme activity of EcoRI was somewhat conserved after interaction with CdS QDs. This study contributed to a better understanding of protein-NPs interaction and created a framework for applications of nanomaterial-biomolecule conjugation in some fields such as nanobiology and nanomedicine. (C) 2014 Elsevier B.V. All rights reserved.