Photo Relaxation Change and Emission Quenching in Different Sizes of PbS‐Nanoparticles‐Protein Corona

Abstract

AbstractIn this study, energy transfer from BSA to different size semiconductor nanoparticles PbS was analyzed by using photo Relaxation change and emission quenching analysis. Structures of thePbS NPs are studied by XRD, TEM, and FT‐IR measurements. The band gap and crystal size of PbS suggest the quantum confinement effect. Photo current of the BSA‐PbS NPs bioconjugate system increased compared to bare PbS nanoparticles from nA to μA. Change in photo relaxation life time of the bare PbS NP and PbS NPs‐BSA bioconjugate system is particle size dependent and interaction dependent. PbS NPs‐BSA bioconjugate were characterized by steady‐state fluorescence spectroscopy to determine the magnitude and mechanism of the energy transfer. It was found that the BSA fluorescence was quenched after the addition of PbS nanoparticles. Quenching of protein is large for larger size PbS nanoparticles. DLS study confirmed that BSA was adsorbed onto the surface of nanoparticles, creating a favourable geometry for quenching. Aggregation of BSA around a single PbS nanoparticle is size dependent. Larger nanoparticles are responsible for hard as well as soft corona due to interaction.Our results, which include photo relaxation times, energy transfer efficiencies showed that energy transferred take place via the Fluorescence Resonance Energy Transfer (FRET) mechanism. These energy transfer processes between protein molecules and PbS nanoparticles, will depend on the size of the particles involved.