Poly(lactic-co-glycolic acid) nanoparticles for sustained release of allyl isothiocyanate: characterization, in vitro release and biological activity.

The objective of this study is to establish the ability of entrap allyl isothiocyanate (AITC) into polymeric nanoparticles to extend its shelf life and enhance its antiproliferative properties. Natural compounds, such as AITC, have showed multi-targeting activity resulting in a wide-range spectrum of therapeutic properties in chronic and degenerative diseases, conversely with most current pharmaceutical drugs showing single targeting activity and often result in drug resistance after extended administration periods. Apparently, AITC-loaded poly(lactic-co-glycolic acid) nanoparticles (PLGA NPs) reduced AITC degradation and volatility and were able to extend AITC shelf life compared with free AITC (65% vs. 20% in 24 h, respectively). Cell viability and uptake of AITC-loaded nanoparticles were studied in vitro, showing that the protection and sustained release of AITC from polymeric NPs involved a larger toxicity of tumoral cells. These nanoparticles could be used as protective systems for enhancing a biological activity.

Targeted Drug Delivery Via Human Epidermal Growth Factor Receptor for Sustained Release of Allyl Isothiocyanate.

In this study, allyl-isothiocyanate (AITC)-loaded Polylactic-Co-Glycolic Acid (PLGA) Nanoparticles (NPs) were prepared for targeting epithelial squamous carcinoma cells using a specific antibody targeting the Epidermal Growth Factor (EGF) receptor overexpressed on the cell membranes. AITC-loaded PLGA NPs showed more effective anticancer properties compared with free AITC, and their cytotoxicity was even more pronounced when the anti-EGFR antibody was covalently attached to the NPs surface. This targeting ability was additionally tested by co-culturing cervical HeLa cells, with very few EGFR on the membranes, and epithelial squamous carcinoma A431 cells, which largely overexpressed EFGR, being observed the specific localization of the antibody-functionalized AITC-loaded PLGA NPs solely in the latter types of cells, whereas non-functionalized NPs were distributed randomly in both cell types in much lesser extents. Thus, our findings support the development of drug delivery strategies that enhances the delivery of anti-cancer natural compounds to tumor tissue, in this case, by targeting specific tumor cell receptors with cell-specific ligands followed by tumor sensitization.

Oligomers, protofibrils and amyloid fibrils from recombinant human lysozyme (rHL): fibrillation process and cytotoxicity evaluation for ARPE-19 cell line.

Amyloid-associated diseases, such Alzheimer's, Huntington's, Parkinson's, and type II diabetes, are related to protein misfolding and aggregation. Herein, the time evolution of scattered light intensity, hydrophobic properties, and conformational changes during fibrillation processes of rHL solutions at 55 °C and pH 2.0 were used to monitor the aggregation process of recombinant human lysozyme (rHL). Dynamic light scattering (DLS), thioflavin T (ThT) fluorescence, and surface tension (ST) at the air-water interface were used to analyze the hydrophobic properties of pre-amyloid aggregates involved in the fibrillation process of rHL to find a correlation between the hydrophobic character of oligomers, protofibrils and amyloid aggregates with the gain in cross-ß-sheet structure, depending on the increase in the incubation periods. The ability of the different aggregates of rHL isolated during the fibrillation process to be adsorbed at the air-water interface can provide important information about the hydrophobic properties of the protein, which can be related to changes in the secondary structure of rHL, resulting in cytotoxic or non-cytotoxic species. Thus, we evaluated the cytotoxic effect of oligomers, protofibrils and amyloid fibrils on the cell line ARPE-19 using the MTT reduction test. The more cytotoxic protein species arose after a 600-min incubation time, suggesting that the hydrophobic character of pre-amyloid fibrils, in addition to the high prevalence of the cross-ß-sheet conformation, can become toxic for the cell line ARPE-19.

Interaction and cytotoxic effects of hydrophobized chitosan nanoparticles on MDA-MB-231, HeLa and Arpe-19 cell lines.

In this work, we investigate the effect of chitosan hydrophobization on the internalization and cytotoxic effect of chitosan-based nanoparticles (NPs) on breast cancer cells (MDA-MB-231), cervical cancer cells (HeLa) and noncancer cells (Arpe-19). We also analyzed the interaction of NPs with a phospholipid (DPPC) membrane model at the airwater interface. An alkylation procedure to insert 8 carbon chains along the chitosan macromolecule with final 10 and 30 % substitution degrees was used. Nuclear magnetic resonance (NMR) and infrared spectroscopes (IR) were used to evaluate the success and extent of the hydrophobization procedure. Size, shape, and charge of NPs were evaluated by dynamic light scattering (DLS), atomic force microscope (AFM), and zeta potential, respectively. The effect of hydrophobicity on NPs was the reduction of the NPs average size, the formation of slightly elongated structures and the enhancing of the interaction of NPs with a DPPC monolayer at the air-water interface. By using fluorescence images on fluorescein-chitosan NPs, we observed a higher internalization of hydrophobic chitosan NPs in cancer cells in comparison with a low internalization of these NPs in normal cells. Even when non modified chitosan NPs were highly internalized in all cell lines, hydrophobized chitosan NPs showed a significantly higher cytotoxic effect on cancer cells in comparison with a lower effect showed by non-modified chitosan NPs on these cells. The cytotoxic effect on the normal cell line used was low for native chitosan NPs and negligible for hydrophobized chitosan NPs.

Interaction of the cationic peptide bactenecin with mixed phospholipid monolayers at the air-water interface.

The initial mechanism by which antimicrobial peptides target microbes occurs via electrostatic interactions; however, the mechanism is not well understood. We investigate the interaction of the antimicrobial peptide bactenecin with a 50:50 w:w% 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and 1,2-dimyristoyl-sn-glycero-3-phospho-(1'-rac-glycerol) (DMPG) phospholipid mixture at the air-water interface with different NaCl concentrations (0.01, 0.05, 0.1, 0.5 M) in the subphase. A larger shift of DPPC:DMPG isotherms was obtained for 0.1 M salt concentration at lower and higher pressures, demonstrating the influence of the negative charge of DMPG molecules and the screening of the electrostatic interaction by the salt concentration. Raman spectroscopy of monolayers demonstrated the presence of cysteine-cysteine bridges in bactenecin loops. The peptide adsorption in DPPC:DMPG monolayers observed by AFM images suggests a self-assembled aggregation process, starting with filament-like networks. Domains similar to carpets were formed and pore structures were obtained after a critical peptide concentration, according to the carpet model.

Chitosan-cholesterol and chitosan-stearic acid interactions at the air-water interface.

We report in this work the isotherms of cholesterol and stearic acid at the air-water interface modified by different chitosans (chitosan chloride, hydrophobic modified chitosan, and medium and high molecular weight chitosans) in the aqueous subphase. The Langmuir-Blodgett films of the complexes cholesterol-chitosan and stearic acid-chitosan are analyzed by atomic force microscopy (AFM), and a molecular simulation was performed to visualize the chitosan-lipid interactions. Strong modifications are obtained in the isotherms as a result of the chitosan interactions with cholesterol and stearic acid at the air-water interface. These modifications were dependent on the type and concentration of chitosan. Severe modifications of all phases were noticed with larger molecular areas, and the observed changes in the compressional modulus were dependent on the type of chitosan used. The complexes of chitosan-stearic acid were more flexible than the ones of chitosan-cholesterol. The AFM images demonstrated that chitosan was disaggregated by the cholesterol and stearic acid interactions producing more homogeneous surfaces in some cases. The hydrophobic chitosan showed more affinity with stearic acid, while both medium and high molecular weight chitosans produced homogeneous surfaces with cholesterol. The simulated chitosan chains interacting with cholesterol and stearic acid demonstrated the possibility of specific sites of electrostatic bonds between these molecules. Adsorption of cholesterol on the different powdered chitosans, performed by HPLC, showed that the medium and high molecular weight chitosans could retain higher proportions of cholesterol compared with the other analyzed samples.