The effect of cosolvents on the formulation of nanoparticles from low-molecular-weight poly(I)lactide

The aim of this study was to formulate nanoparticles from poly(I)lactide by a modified nanoprecipitation method. The main focus was to study the effect of cosolvent selection on the shape, size, formation efficiency, degree of crystallinity, x-ray diffraction (XRD) reflection pattern, and zeta potential value of the particles. Low-molecular-weight (2000 g/mol) poly(I)lactide was used as a polymer, and sodium cromoglycate was used as a drug. Acetone, ethanol, and methanol were selected as cosolvents. Optimal nanoparticles were achieved with ethanol as a cosolvent, and the formation efficiency of the particles was also higher with ethanol as compared with acetone or methanol. The particles formulated by ethanol and acetone appeared round and smooth, while with methanol they were slightly angular. When the volume of the inner phase was decreased during the nanoprecipitation process, the mean particle size was also decreased with all the solvents, but the particles were more prone to aggregate. The XRD reflection pattern and the degree of crystallinity were more dependent were more prone to aggregate. The XRD reflection pattern and the degree of crystallinity were more dependent on the amount of the solvents in the inner phase than on the properties of the individual cosolvents. The zeta potential values of all the particle batches were slightly negative, which partially explains the increased tendency toward particle aggregation.     

Ethanol injection method for hydrophilic and lipophilic drug-loaded liposome preparation

In this article, a hydrophobic (beclomethasone dipropionate; BDP) and a hydrophilic (cytarabine; Ara-C) drugs have been encapsulated in liposomes in order to be administered via the pulmonary route. For this aim, a liposome preparation method, which is easy to scale up, the ethanol injection method, has been selected. The effects of critical process and formulation parameters have been investigated. The drug-loaded liposomes were prepared and characterized in terms of size, zeta potential, encapsulation efficiency, release study, cell uptake, and aerodynamic behavior. Small multilamellar vesicles, with sizes ranging from about 80 to 170?nm, were successfully obtained. Results indicated a significant influence of phospholipid and cholesterol amounts on liposome size and encapsulation efficiency. The higher encapsulation efficiencies were about 100% for the hydrophobic drug (BDP) and about 16% for the hydrophilic one (Ara-C). The in vitro release study showed a prolonged release profile for BDP, in contrast with Ara-C, which was released more rapidly. The cell-uptake test revealed that fluorescent liposomes have been well internalized into the cytoplasm of SW-1573 human lung carcinoma cells, confirming the possibility to use liposomes for lung cell targeting. Nebulized Ara-C and BDP liposomes presented aerodynamic diameters compatible with deep lung deposition. In conclusion, the elaborated liposomes seem to be promising carriers for both Ara-C and BDP pulmonary delivery.     

Biodegradable delivery system containing a peptide inhibitor of polyglutamine aggregation: a step toward therapeutic development in Huntington's disease

Huntington's and eight other neurodegenerative diseases occur because of CAG repeat expansion mutation culminating into an expanded polyglutamine tract in respective protein. In Huntington's disease (HD), a number of CAG repeats beyond normal repeat length (>36) lead to the formation of mutant protein, the proteolytic cleavage of which induces aggregation in polyglutamine length‐dependent manner. The neurodegeneration in this disease is linked to aggregation, and its inhibition is a potential approach for therapeutic development. Although peptides and other molecules have been developed for inhibiting aggregation, peptides in general are susceptible to degradation in vivo conditions. To understand their clinical significance, they also need to be delivered through blood–brain barrier. Here, for the first time, we have synthesized poly‐d ,l ‐lactide‐co‐glycolide nanoparticles containing a polyglutamine aggregation inhibitor peptide PGQ₉[P²], by nanoprecipitation method. This process yielded less than 200 nm spherical nanoparticles with uniform distribution. Characterization studies by infrared spectroscopy‐based and HPLC‐based assays show the presence of PGQ₉[P²] in nanoparticles. In vitro release kinetics demonstrates that nanoparticles release PGQ₉[P²] by erosion and diffusion processes. When the PGQ₉[P²]‐loaded nanoparticles are incubated with aggregation‐prone Q₃₅P₁₀ peptide, representing N‐terminal part of Huntingtin protein, it arrests the elongation phase of Q₃₅P₁₀ aggregation. These findings propose the first step toward delivery of a peptide inhibitor against polyglutamine aggregation in HD. Copyright © 2014 European Peptide Society and John Wiley & Sons, Ltd.     

Synthesis and ITC characterization of novel nanoparticles constituted by poly(gamma-benzyl L-glutamate)-beta-cyclodextrin

Imparting desired technological characteristics to polymeric nanoparticles requires the development of original polymers. In the present work, the synthesis and characterization of a novel PBLG-derivative, the poly(gamma-benzyl L-glutamate)-beta-cyclodextrin (PBLG-beta-CD-50), have been carried out. Nanoparticles from either PBLG-beta-CD-50 polymer or from mixtures with PBLG have been prepared using a modified nanoprecipitation method. Spherically shaped nanoparticles with diameter in the range of 50-70 nm were obtained, as determined by dynamic laser light scattering and transmission electron microscopy. The presence of a surfactant in the suspension medium had almost no influence on these parameters and was not necessary to the shelf-stability of the suspension. Further, isothermal titration microcalorimetry (ITC) experiments have been used to show unambiguously that about 20% of the cyclodextrins remain functional within the particles. Consequently, this system may be of interest when association of large amounts of hydrophobic drugs to nanoparticles is required.     

Nanoprecipitation versus emulsion-based techniques for the encapsulation of proteins into biodegradable nanoparticles and process-related stability issues

The goal of this study was to investigate the entrapment of 3 different model proteins (tetanus toxoid, lysozyme, and insulin) into poly(D,L-lactic acid) and poly(D,L-lactic-co-glycolic acid) nanoparticles and to address process-related stability issues. For that purpose, a modified nanoprecipitation method as well as 2 emulsion-based encapsulation techniques (ie, a solid-in oil-in water (s/o/w) and a double emulsion (w₁/o/w₂) method) were used. The main modification of nanoprecipitation involved the use of a wide range of miscible organic solvents such as dimethylsulfoxide and ethanol instead of the common acetone and water. The results obtained showed that tetanus toxoid and lysozyme were efficiently incorporated by the double emulsion procedure when ethyl acetate was used as solvent (>80% entrapment efficiency), whereas it was necessary to use methylene chloride to achieve high insulin entrapment efficiencies. The use of the s/o/w method or the formation of a more hydrophobic protein-surfactant ion pair did not improve protein loading. The nanoprecipitation method led to a homogenous population of small nanoparticles (with size ranging from ≈130 to 560 nm) and in some cases also improved experimental drug loadings, especially for lysozyme (entrapment efficiency >90%). With respect to drug content determination, a simple and quick matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) method provided results very close to those obtained by reverse phase-high-performance liquid chromatography. With respect to protein stability, the duration and intensity of sonication were not a concern for tetanus toxoid, which retained more than 95% of its antigenicity after treatment for 1 minute. Only a high methylene chloride:water ratio was shown to slightly decrease toxoid antigenicity. Finally, no more than 3.3% of A21 desamido insulin and only traces of covalent insulin dimer were detected in nanoparticles. In conclusion, both the double emulsion and nanoprecipitation methods allowed efficient protein encapsulation. MALDI-TOF MS allowed accurate drug content determination. The manufacturing processes evaluated did not damage the primary structure of insulin. Published: December 1, 2005     

Insecticidal activity of polycaprolactone nanocapsules loaded with Rosmarinus officinalis essential oil in Tribolium castaneum (Herbst)

In this study, the opportunity to enhance the insecticidal activity of Rosmarinus officinalis essential oil was studied for effective management of the red flour beetle, Tribolium castaneum , as a stored product pest beetle. Nanoprecipitation method was used to prepare rosemary oil‐loaded nanocapsules. Bioassays were conducted at 27–30°C temperature and 70–75 % relative humidity in the dark. Fumigant toxicity of the non‐formulated oil and nanocapsules of R. officinalis were investigated at 13.20, 15.92, 19.12, 23.04, and 27.76 μL/L air after 24 and 72 h exposure and the contact toxicity of the non‐formulated oil and nanocapsules were investigated at 4.28, 3.55, 2.95, 2.45 and 2.36 μL/cm² after 24 h exposure. The major constituents of the essential oil of rosemary were α‐Pinene, 1,8‐cineol, camphor, and cis‐verbenone. Nanocapsules presented an average size (145 ± 15 nm) (± standard error [SE]) with a polydispersity index below 0.3, a negative zeta potential (?11.0 ± 0.5 mV), and a high encapsulation efficiency (78.20 ± 0.93 %). Scanning electron microscope photomicrograph of rosemary oil‐loaded nanocapsules showed the presence of spherical nanocapsules with regular and homogeneous surfaces. In fumigant and contact toxicity, there were significant differences between non‐formulated and rosemary oil‐loaded nanocapsules in all the concentrations and times. The results suggested that nanoencapsulated essential oils from R. officinalis can be used for effective control in T. castaneum . When this technique is used, it can produce pesticides that have controlled‐release properties and reduce the concentration of the applied doses and number of applications.