Optical properties effect of cadmium sulfide quantum dots towards conjugation process

Abstract

Sphere-shaped cadmium sulfide quantum dots (CdS QDs) with well-controlled morphology and uniform size were successfully synthesized by using simple colloidal method with addition of thiolglycolic acid as stabilizer. Size and optical properties of CdS QDs could be tuned by altering the CdS QDs surface with capped ligand Polyethylenimine (PEI) while their aqueous isoelectric charge was adjusted by changing the pH solution with added sodium hydroxide (NaOH). Morphology, optical properties and surface charge of CdS QDs have been characterized by transmitted electron microscopic (TEM), absorption spectra analysis, photoluminescence spectroscopy and Nanozeta potential, respectively. Furthermore, CdS-lysozyme conjugates have been obtained by electrostatic interaction between CdS QDs and lysozyme, which is lysozyme protein with isoelectric +11.2 mV. Surface change after conjugation process was investigated. Optical absorption edge and intensity of luminescence was not affected after conjugation process. © 2011 Springer-Verlag.