Sundararajan Parani

Gelatin stabilization of quantum dots for improved stability and biocompatibility

We herein report an aqueous synthesis of gelatin stabilized CdTe/CdS/ZnS (CSSG) core/double shell quantum dots (QDs) with improved biocompatibility. The as-synthesized QDs were characterized by ultraviolet-visible (UV-vis) and photoluminescence (PL) spectroscopic techniques, x-ray diffraction technique (XRD), x-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The CSSG QDs revealed high photoluminescence quantum yield (PLQY) with excellent stability over a period of one year and retained 90% of its initial PLQY without any aggregation or precipitation under ambient condition. The cell viability study conducted on HeLa, cervical cancer cell lines indicated that the gelatin stabilization effectively decreased the QDs cytotoxicity by about 50%. The CSSG QDs were conjugated with transferrin (Tf) for the efficient delivery to the cancer cells followed by fluorescence imaging. The results showed that the CSSG QDs illuminates the entire cell which renders the QDs as cell labeling markers. The gelatin stabilized core/double shell QDs are potential candidates for long time fluorescent bio-imaging.

Preparation, characterization and in vitro release study of β-cyclodextrin/chitosan nanoparticles loaded Cinnamomum zeylanicum essential oil

Cinnamomum zeylanicum essential oil (CEO) is an effective antimicrobial agent. However, its high volatile nature and low stability require an efficient encapsulation system for drug delivery applications. We herein report the synthesis of β-cyclodextrin modified chitosan (β-CD/CS) nanoparticles binary system via ionic gelation method for the controlled release of CEO. The nanoparticles were characterized by optical and structural spectroscopies followed by the in-vitro released study. The results showed that the particles are spherical in shape with positively charged surface and maximum encapsulation efficiency of 58.03%. In vitro release profiles showed an overall CEO release of 71% for the binary system compared to 49% for CEO- loaded chitosan (CS) nanoparticles single system. The release mechanism followed Fickian behaviour while in vitro CEO release analysis showed a sustained and controlled release for over 120 h. The as-synthesized β-cyclodextrin/chitosan nanoparticles offer a promising system for enhancing the therapeutic effect of CEO.

Facile Size Tunable Green Synthesis of Highly Fluorescent Isotropic and Anisotropic CdSe Nanostructures via a Non-phosphine Based Route

We herein report a phosphine-free synthesis of high quality isotropic and anisotropic CdSe nanostructures (NSs) using oleic acid as capping agent and paraffin as the reaction solvent. The effect of Cd:Se ratio and concentration on the optical and structural properties were investigated by UV–Vis absorption and photoluminescence (PL) spectroscopy and high resolution transmission electron microscopy (HRTEM). The optical analysis revealed a red shift in the absorption band and decrease in the Stoke shift as the reaction time and Cd:Se mole ratio increased. The PL quantum yield of the CdSe NSs at higher cadmium precursor concentration (87%) was higher than that obtained at lower precursor concentration (55%). HRTEM analysis showed that small, spherical and mono-dispersed isotropic quantum dots were produced at lower cadmium concentration and at lower Cd:Se ratio while nanorods were produced at higher Cd:Se ratio. At higher precursor concentration and 1:1 Cd:Se ratio, spherical particles were produced at the beginning of the reaction followed by mixtures of spherical and anisotropic structures—rod, triangular, hexagonal and pentagonal nanostructures. Increasing the Cd:Se ratio to 2:1 at higher cadmium concentration resulted in the formation of spherical particles. This synthetic method is simple, rapid, reproducible, cost effective and environmentally benign.