Hemant P. Soni

Inducing chirality on ZnS nanoparticles for asymmetric aldol condensation reactions

L-Proline immobilized ZnS nanoparticles (NPs) were synthesized by a simple wet chemical method and characterized by XRD. The as-synthesized NPs were used as a catalyst for the direct asymmetric aldol reaction of several aldehydes with acetone to achieve chiral β-hydroxy carbonyl compounds in good yields and enantioselectivity at room temperature. The peculiarity of our strategy is that the reaction is carried out at room temperature and does not involve any co-solvent for solubility purposes. The selectivity of the developed heterogeneous catalyst leads to only (R)-β-hydroxy carbonyl compounds and restricts the reaction at the aldolization stage only, without any formation of dehydrated α,β-unsaturated product. The modified reaction mechanism, showing the involvement of surface Zn+2 ions, is proposed. The catalyst was recovered and reused several times without any significant lost in activity. This opens new avenues for surface engineering leading to green catalytic processes.

Immobilization of Thermomyces lanuginosus lipase on ZnO nanoparticles: mimicking the interfacial environment

Thermomyces lanuginosus lipase (TL lipase) was immobilized covalently on ZnO nanoparticles (NPs) functionalized with small amino acid molecules, like glycine. Glutaraldehyde was used as a spacer between the ZnO/glycine Nps and the enzyme. This study is based on the observation that the favorable conformation of an enzyme (in which the catalytic lid is exposed to reactant molecules) can be obtained at the lipid/water interface and such an interfacial environment can be mimicked by properly designing the carrier used as the support for its immobilization. Glycine functionalized ZnO NPs were covalently bonded with glutaraldehyde and consequently TL lipase enzyme immobilization was carried out by a simple wet chemical method. The resulting assemblies were characterized by using techniques like XRD, UV absorption and photoluminescence spectroscopy. The particle size was determined by using Transmission Electron Microscopy (TEM). The immobilized TL lipase enzyme showed high activity for esterification of oleic acid (C-18) with methanol in an organic medium. The catalyst was recovered and reused several times without any significant loss of activity.

EDTA capped iron oxide nanoparticles magnetic micelles: drug delivery vehicle for treatment of chronic myeloid leukemia and T1–T2 dual contrast agent for magnetic resonance imaging

Ethylene diamine tetra acetate (EDTA) capped Fe3O4 nanoparticles (NPs) have been synthesized and encapsulated using polymeric micelles. The synthesized Fe3O4/EDTA/P magnetic micelles are used as a vehicle to load the hydrophobic drug imatinib and transfect it in a bone marrow cell-line (K562) in vitro for the treatment of chronic myeloid leukemia. From FTIR spectroscopy it is established that EDTA coordinates bidentately with the surface Fe ions. From the vibrating sample magnetometry (VSM) study, the shape of the magnetization curve indicates superparamagnetic behavior in the presence of a magnetic field. The hydrodynamic diameter measured by dynamic light scattering (DLS) is found to be 440 nm within the upper limit (500 nm) required to transfect into the cell. An in vitro drug release kinetics study reveals that approximately 60% of the drug is released at the end of 196 h. Notably, the drug-loaded magnetic micelles display much lower liver accumulation compared to the bare drug, indicating prolonged circulation time and maximum availability at the bone marrow. In vivo magnetic resonance (MR) imaging conducted on nude mice bearing the synthesized magnetic micelle after i.v. administration reveals excellent imaging capabilities, in dual mode, especially 24 h post-injection. We propose that the longitudinal relaxation (T1) of water protons can be induced by mimicking Gd-DTPA chelate chemistry while transverse relaxation (T2) can be achieved by controlling the particle size.

Transfecting pDNA to E. coli DH5α using bovine serum albumin nanoparticles as a delivery vehicle

We describe the formulation of bovine serum albumin nanoparticles (BSA-NPs) by the coacervation method using surfactants. Plasmids (pUC18, pUC18egfp and pBBR1MCS-2) isolated from E. coli were incorporated into the BSA matrix by incubating in albumin solution prior to formulation of NPs. Plasmid incorporation was calculated by % yield, entrapment efficiency, DNA loading capacity and release of entrapped DNA by comparing with blank NPs. BSA-DNA binding studies were carried out by using fluorescence spectroscopy and Fourier Transform Infra Red Spectroscopy (FT-IR). The surface charge distribution of the NPs loaded with plasmid was calculated using zeta potential. The photoluminescence of BSA-NPs was quenched when loaded with pDNA, confirming the interaction of DNA with BSA. Altogether, these results provide evidences for the excellent DNA carrying efficiency of BSA-NPs without loss of plasmids integrity. The NPs were used to transfect E. coli DH5α strain lacking ampicillin resistance. They, however, showed ampicillin resistance subsequent to transfection with plasmid encoding ampicillin resistance gene. Effect of transfection was confirmed by confocal microscopy and by the isolation of the plasmid by agarose gel electrophoresis from the transfected bacterial culture. This study clearly demonstrates the efficacy of BSA-NPs as delivery vehicle for pDNA transfection.