Structural and Functional Characterization of Enzyme-Quantum Dot Conjugates: Covalent Attachment of CdS Nanocrystal to r-Chymotrypsin
نویسندگان
چکیده
In this contribution, we report the synthesis of CdS nanoparticles directly conjugated to an enzyme, R-chymotrypsin (CHT) by chemical reduction in aqueous solution. Matrix-assisted laser desorption ionization (MALDI) mass spectrometry confirms the strong conjugation of CdS nanoparticles to CHT through covalent bonding in the CdS-CHT conjugates. High-resolution transmission electron microscopy (HRTEM) reveals that the CdS nanoparticles are well dispersed with an average diameter of 3 nm, and energy dispersive X-ray elemental analysis (EDAX) verifies the composition of the CdS-protein conjugates. The structural integrity of CHT before and after the conjugation of CdS nanoparticles is confirmed through circular dichroism (CD) studies. The functional integrity of CHT conjugated to CdS nanoparticles is investigated by monitoring the enzymatic activities of CHT and CHT-conjugated CdS nanoparticles by using absorption spectroscopy. The attachment of CdS nanoparticles to an enzyme with its structural and functional integrity may have impact in the future research on nanobio interface.
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