Smart Magnetic Nanocarriers for Codelivery of Nitric Oxide and Doxorubicin for Enhanced Apoptosis in Cancer Cells.

Extremely short half-life therapeutic molecule nitric oxide (NO) plays significant roles in the functioning of various physiological and pathological processes in the human body, whereas doxorubicin hydrochloride (DOX) is a clinically important anticancer drug widely used in cancer chemotherapy. Thus, the intracellular delivery of these therapeutic molecules is tremendously important to achieve their full potential. Herein, we report a novel approach for the development of highly water-dispersible magnetic nanocarriers for codelivery of NO and DOX. Primarily, bifunctional magnetic nanoparticles enriched with carboxyl and thiol groups were prepared by introducing cysteine onto the surface of citrate-functionalized Fe3O4 nanoparticles. DOX was electrostatically conjugated onto the surface of bifunctional nanoparticles via carboxyl moieties, whereas the thiol group was further nitrosated to provide NO-releasing molecules. The developed magnetic nanocarrier exhibited good aqueous colloidal stability, protein resistance behavior, and high encapsulation efficacy for NO (65.5%) and DOX (85%), as well as sustained release characteristics. Moreover, they showed superior cytotoxicity toward cancer (A549 and MCF-7) cells via apoptosis induction over normal (WI26VA4) cells. Specifically, we have developed magnetic nanocarriers having the capability of dual delivery of NO and DOX, which holds great potential for combinatorial cancer treatment.

Spontaneous Formation of Cationic Vesicles in Aqueous DDAB-Lecithin Mixtures for Efficient Plasmid DNA Complexation and Gene Transfection.

Cationic liposomes have become an attractive tool to deliver genes and interfering RNA into cells. Herein, we report the application of spontaneously formed cationic vesicles in mixtures of lecithin and cationic amphiphiles for efficient transfection of plasmid DNA and siRNA into cells. The average hydrodynamic diameter of the phospholipid vesicles was modulated by changing the ratio of dihexadecyldimethylammonium bromide (DDAB) to phospholipid in the vesicles. The vesicles were characterized by dynamic light scattering, ζ potential, and small-angle X-ray scattering. Depending on the ratio of DDAB to phospholipid, the average size of the vesicles can be varied in the range of 150-300 nm with a ζ potential of +40 mV. The ability of these cationic vesicles to form lipoplexes upon binding with pDNA is demonstrated by ζ potential, isothermal titration calorimetry, gel retardation, and DNase I digestion assay. The enthalpy of binding between pDNA and cationic liposome was found to be -5.7 (±0.8) kJ/mol. The cellular uptake studies of lipoplexes observed by fluorescence microscopy confirmed good transfection efficiency of DDAB liposomes in MCF-7 and HeLa cells. The fluorescent imaging analysis showed effective gene delivery and expression of green fluorescent protein. In addition, the formulation has demonstrated an ability to deliver small interfering RNA (siBRD4) for efficient gene silencing as seen by a significant decrease in BRD4 protein level in siBRD4-treated cells. Comparison of the transfection efficiency of different formulations suggests that DDAB-rich mixed phospholipid vesicles with size <200 nm are better than large size vesicles for improved endocytosis and gene expression.

Electrostatically bound lanreotide peptide - gold nanoparticle conjugates for enhanced uptake in SSTR2-positive cancer cells.

Lanreotide peptide (LP) has high affinity to somatostatin receptors like SSTR2 and is commonly used in the treatment of neuro-endocrine tumors. The main objective of this study is to target gold nanoparticles (AuNPs) towards SSTR2-positive cancer cells using lanreotide peptide (LP) as the targeting agent for enhanced tumor uptake and antitumor activity. pH mediated changes in the surface potential of LP and AuNP is used to prepare electrostatically bound AuNP-LP complexes. AuNP-LP complex formation was demonstrated by UV-Visible spectroscopy, surface potential, dynamic light scattering (DLS), small angle X-ray scattering and HR-TEM. Confocal microscopy and flow cytometric studies show that AuNP-LP complex has higher cellular uptake in SSTR2 expressed cancer cells (MCF-7 and AR42J) than in CHO cells. The enhanced cellular uptake of LP coated AuNPs lead to ~1.5 to 2-fold GSH depletion and enhanced ROS generation in MCF-7 cells. The preferential cytotoxicity of the AuNP-LP complex towards MCF-7 and AR42J cells, as revealed by MTT assay, is consistent with the increased cellular uptake. Our studies demonstrate that LP coated AuNP can be used as an effective platform to selectively target SSTR2 positive cancer cells for combination therapy approaches involving gold nanoparticles.

Altering the X-ray Scattering Contrast of Triton X-100 Micelles and Its Trapping in a Supercooled Solvent.

The structure of core-shell micelles formed by nonionic surfactant Triton X-100 (TX-100) in a supercooled glucose-urea melt is investigated by contrast variation small-angle X-ray scattering (SAXS), small angle neutron scattering (SANS), and HR-TEM. Cooling a molten mixture of glucose-urea (weight ratio of 3:2) to room temperature yields a supercooled solvent without crystallization that can be used for trapping micelles of TX-100. By use of a combination of water and glucose-urea mixture at different proportions as solvent for micellization, the scattering length density (SLD) of the solvent can be tuned to match the shell contrast of the micelles. A systematic analysis of SAXS and SANS data with different SLD of solvent permits a quantitative evaluation of electron density profile of micelles in different matrices. The core of TX-100 micelles shows significant swelling in glucose-urea melt, as compared to that in water. The dimension and morphology of micelles were evaluated by scattering techniques and HR-TEM. Dynamic light scattering (DLS) studies suggest that, unlike micelles in water, the diffusion of micelles in supercooled glucose-urea melt decreased by several orders of magnitude.

pH-Labile Magnetic Nanocarriers for Intracellular Drug Delivery to Tumor Cells.

We report the development of pH-labile ascorbic acid-coated magnetic nanocarriers (AMNCs) for effective delivery of the anticancer drug doxorubicin hydrochloride (DOX) to tumor cells. The uniqueness of this drug delivery system lies in the covalent conjugation of DOX through carbamate and hydrazone bonds, resulting in a slow and sustained drug release profile at different environmental acidities. X-ray diffraction and transmission electron microscopy analyses reveal the formation of crystalline single-phase Fe3O4 nanoparticles with an average size of 10 nm. The changes in the interfacial characteristics of the nanocarriers and the presence of organic coatings are probed by infrared spectroscopy, dynamic light scattering, zeta potential, and thermogravimetric measurements. AMNCs show high colloidal stability in aqueous and cell culture media and possess good magnetic field responsivity and protein resistance characteristics. The drug-loaded nanocarriers exhibited sustained pH-triggered release of drug molecules in acidic mediums, substantial cellular internalization, and significant toxicity toward the proliferation of mouse skin fibrosarcoma (WEHI-164), human breast cancer (MCF-7), and human lung cancer (A549) cells. However, it showed significantly lower toxicity in human normal lung (WI26VA) cells. Overall, these results suggest a pH-sensitive drug release of nanoformulations, which showed selective toxicity to tumor than normal cells.