In this work, we investigate the influence of chitosan hydrophobization on the formation, physicochemical properties, solubilization, and release profiles of chitosan‐based nanoparticles (NPs) complexed with the protein insulin, used as a protein model. We use an alkylation procedure to insert 8, 10, and 12 carbon chains along the chitosan macromolecule with a final 5, 10, or 50% substitution degree. Nuclear magnetic resonance (NMR) and infrared spectroscopes (IR) were used to evaluate the success and extent of the hydrophobization procedure. The size, shape, and charge of bare polymer and polymer‐insulin NPs were evaluated by dynamic light scattering (DLS), transmission electron (TEM), and atomic force (AFM) microscopes, and zeta potential, respectively. DLS and zeta potential data demonstrated that polymeric NPs made with hydrophobized chitosans possess smaller sizes and higher positive charges than NPs obtained with unmodified chitosan. Also, TEM and AFM images showed that modified chitosan‐made NPs have more elongated structures. Isothermal titration calorimetry (ITC) was used to determine the type and extent of the existing interactions between the different constituting components of complexed insulin‐hydrophobized chitosan nanoparticles. The association efficiency and loading capacity of insulin into the polymeric nanoparticles were also investigated under different solution conditions. Our results showed that hydrophobized chitosan‐based NPs possess both higher association efficiencies and protein loading capacities at pH 6 in comparison with unmodified chitosan‐based ones. In vitro protein release studies at pH 5.3, 6, and 7.4 demonstrated that insulin is released more slowly from hydrophobized chitosan NPs, which would favor a more sustained protein release. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Despite the use of small interfering RNAs (siRNAs) as therapeutic agents through the knockdown expression of pathogenic proteins, transportation and delivery of such siRNAs into cells continue to be under investigation. Within nonviral vectors, cationic lipids that include amino acid residues in their structures, and that have already demonstrated their suitability as plasmid DNA nanocarriers, may be also considered as potential siRNA vehicles. A double-chain cationic lipid based on the amino acid arginine mixed with a helper lipid has been the object of this biophysical study. First, ζ-potential measurements and agarose gel electrophoresis experiments confirmed the siRNA compaction, while small-angle X-ray scattering analysis (SAXS) revealed the structural pattern of the lipoplexes. Two bicontinuous cubic phases were found to coexist: the double-gyroid phase (Q II G ) and the double-diamond phase (Q II D ), with Pn3m and Ia3d as crystallographic space groups, respectively; the siRNA is known to be located inside their bicontinuous aqueous channels. Second, in vitro studies in HeLa-green fluorescent protein (GFP) and T731-GFP cell lines (modified for GFP overexpression) showed moderate to high gene knockdown levels (determined by flow cytometry and epifluorescence microscopy) with remarkable cell viabilities (CCK-8 assay). Finally, nano-liquid chromatography/mass spectrometry (nanoLC-MS/MS) was used to identify the nature of the proteins adhered to the surface of the lipoplexes after incubation with human serum, simulating their behavior in biological fluids. The abundant presence of lipoproteins and serum albumin in such protein corona, together with the coexistence of the bicontinuous cubic phases, may be behind the remarkable silencing activity of these lipoplexes. The results reported herein show that the use of amino-acidbased cationic lipids mixed with a suitable helper lipid, which have already provided good results as DNA plasmid nanocarriers in cellular transfection processes, may also be a biocompatible option, and so far little investigated, in gene silencing in vitro strategies.

The Biodegradable nanoparticles from poly(lactic-co-glycolic acid) (PLGA) have been extensively investigated for sustained and targeted/localized delivery of different agents. Many parameters are required in the synthesis of a biodegradable polymeric nanoparticle. We report the synthesis of human serum albumin (HSA)-superparamagnetic iron oxide nanoparticles (SPIONs) loaded PLGA nanoparticles. All nanoparticles were characterized using a TEM image, UV-Vis spectroscopy measurements, Zeta Potential, and PPMS for magnetizations. This study described and investigated the interesting phenomenon in the synthesis development of HSA-SPIONs loaded PLGA nanoparticles. The result showed that the stability of HSA-SPIONs loaded PLGA nanoparticles for potential applications such as in protein delivery.

A histidine-based gemini cationic lipid, which had already demonstrated its efficiency as a plasmid DNA (pDNA) nanocarrier, has been used in this work to transfect a small interfering RNA (siRNA) into cancer cells. In combination with the helper lipid monoolein glycerol (MOG), the cationic lipid was used as an antiGFP-siRNA nanovector in a multidisciplinary study. Initially, a biophysical characterization by zeta potential (ζ) and agarose gel electrophoresis experiments was performed to determine the lipid effective charge and confirm siRNA compaction. The lipoplexes formed were arranged in Lα lamellar lyotropic liquid crystal phases with a cluster-type morphology, as cryo-transmission electron microscopy (cryo-TEM) and small-angle X-ray scattering (SAXS) studies revealed. Additionally, in vitro experiments confirmed the high gene knockdown efficiency of the lipid-based nanovehicle as detected by flow cytometry (FC) and epifluorescence microscopy, even better than that of Lipofectamine2000*, the transfecting reagent commonly used as a positive control. Cytotoxicity assays indicated that the nanovector is non-toxic to cells. Finally, using nano-liquid chromatography tandem mass spectrometry (nanoLC-MS/MS), apolipoprotein A-I and A-II followed by serum albumin were identified as the proteins with higher affinity for the surface of the lipoplexes. This fact could be beyond the remarkable silencing activity of the histidine-based lipid nanocarrier herein presented.