DEVELOPMENT AND PERFORMANCE EVALUATION OF TUMOR TARGETING POTENTIAL OF FOLATE SPACER FUNCTIONALIZED SOLID LIPID NANOPARTICLES

Purpose: The objective of the present investigation was to assess the tumor-targeting potential of ligand-spacer engineered solid lipid nanoparticles (SLN) as nanoscale drug delivery units for site-specific delivery of a model anticancer agent, paclitaxel (PTX). SLNs were engineered by direct and indirect conjugation of folic acid (FA) through different types of polyethylene glycols (PEGs) (MW: 1000, 4000) as spacers. Methods: The synthesized nanoconjugates (SLNFA, SLN1FA, and SLN4FA) were characterized by Fourier transform infrared spectroscopy, nuclear magnetic resonance, and transmission electron microscopic studies. Nanoconjugates were evaluated for entrapment, in vitro drug release (under various pH conditions) and hemolytic studies. Cell uptake and cytotoxicity studies were performed on human malignant cell lines (MCF-7) using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Results: This study explored the effect of PEG spacer length on the targeting potential of folate-conjugated SLN. PTX entrapment and in vitro drug release from nanoconjugates augmented, and hemolytic toxicity of nanoconjugates slashed with the molecular weight of PEGs. Further, nanoconjugates with PEG 4000 displayed highest tumor-targeting potential as compared to other spacer conjugated nanoconjugates due to optimized steric hindrance and receptor mediated endocytosis among other PEGs. Conclusion: Engineering of the dendritic surface with targeting ligand such as FA can enhance the site-specific anticancer drug delivery. PEGylation of SLN can improve the circulation time of SLN in the body. This is a debut study reporting FA conjugation to the surface through four PEGs as spacer and optimized the spacer chain length for effective cancer targeting through SLN. This report as a whole is believed to shed new light on the role of spacer chain length in targeting potential of folate-anchored SLN.

Can the Isothermal Calorimetric Curve Shapes Suggest the Structural Changes in Micellar Aggregates?

Inspired by the unusual shapes of the titration curve observed for many surfactants and mixed colloidal systems, we decided to extend the analysis to isothermal titration calorimetric curves (ITC) by paying special attention to potential structural changes in micellar aggregates. In this paper, we used isothermal titration calorimetry in conjunction with Scanning Transmission Electron Microscopy (STEM), Small-Angle Neutron Scattering (SANS) and X-ray Scattering (SAXS) methods support by Monte Carlo and semiempirical quantum chemistry simulations to confirm if the isothermal calorimetric curve shape can reflect micelle transition phenomena. For that purpose, we analysed, from the thermodynamic point of view, a group of cationic gemini surfactants, alkanediyl-α,ω-bis(dimethylalkylammonium) bromides. We proposed the shape of aggregates created by surfactant molecules in aqueous solutions and changes thereof within a wide temperature range. The results provide evidence for the reorganization processes and the relationship (dependence) between the morphology of the created aggregates and the conditions such as temperature, surfactant concentration and spacer chain length which affect the processes.

Synthetic Variation and Structural Trends in Layered Two-Dimensional Alkylammonium Lead Halide Perovskites

We report the cooling-induced crystallization of layered two-dimensional lead halide perovskites with controllable inorganic quantum-well thickness (<i>n</i> = 1, 2, 3, 4)<i>,</i> organic spacer chain length (butyl-, pentyl-, hexylammonium), A-site cation (methylammonium, formamidinium), and halide anion (iodide, bromide). We report crystal structures for the iodide family as a function of these compositional parameters, and across their temperature dependent phase transitions. In general, lower symmetry crystal structures, increasing extents of organic-spacer interdigitation, and increasing organic-spacer corrugation tilts are observed at low temperature. In addition, greater structural distortions are seen in lead halide octahedra closest to the organic spacer layer, and larger-<i>n­ </i>structures exhibit periodic variation in Pb-I bond lengths. We also provide detailed guidance regarding the combination of synthetic parameters needed to achieve phase-pure crystals of each composition, and discuss difficulties encountered when trying to synthesize particular members of the 2D perovskite family containing formamidinium or cesium as the A-site cation. These results provide a foundation for understanding structural trends in 2D lead halide perovskites and the effect these trends have on their thermal, electrical, and optical properties.

Synthetic Variation and Structural Trends in Layered Two-Dimensional Alkylammonium Lead Halide Perovskites

We report the cooling-induced crystallization of layered two-dimensional lead halide perovskites with controllable inorganic quantum-well thickness (<i>n</i> = 1, 2, 3, 4)<i>,</i> organic spacer chain length (butyl-, pentyl-, hexylammonium), A-site cation (methylammonium, formamidinium), and halide anion (iodide, bromide). We report crystal structures for the iodide family as a function of these compositional parameters, and across their temperature dependent phase transitions. In general, lower symmetry crystal structures, increasing extents of organic-spacer interdigitation, and increasing organic-spacer corrugation tilts are observed at low temperature. In addition, greater structural distortions are seen in lead halide octahedra closest to the organic spacer layer, and larger-<i>n­ </i>structures exhibit periodic variation in Pb-I bond lengths. We also provide detailed guidance regarding the combination of synthetic parameters needed to achieve phase-pure crystals of each composition, and discuss difficulties encountered when trying to synthesize particular members of the 2D perovskite family containing formamidinium or cesium as the A-site cation. These results provide a foundation for understanding structural trends in 2D lead halide perovskites and the effect these trends have on their thermal, electrical, and optical properties.

Solvation dynamics and rotational relaxation of coumarin 153 in mixed micelles of Triton X-100 and cationic gemini surfactants: effect of composition and spacer chain length of gemini surfactants

To demonstrate simultaneously how the solvation dynamics and rotational relaxation in nonionic micelles change with the composition of a gemini surfactant and how this change depends on spacer chain length of gemini surfactants.

Effect of spacer chain length on the liquid structure of aqueous dicationic ionic liquid solutions: molecular dynamics studies

Cations in an aqueous [C16(MIm)2][2Br] solution aggregate spontaneously to form micelles, with a hydrophobic core composed of spacer alkyl chains and a hydrophilic surface composed of imidazolium head groups.