Physicochemical Characterization of the Shell Composition of PBCA-Based Polymeric Microbubbles.

Microbubbles (MB) are routinely used as contrast agents for ultrasound (US) imaging. In recent years, MB have also attracted interest as drug delivery systems. Soft-shelled lipidic MB tend to be more advantageous for US imaging, while hard-shelled polymeric MB appear to be more suitable for drug delivery purposes because of their thicker shell and the resulting higher drug loading capacity. The physicochemical composition of the shell of polymeric MB, however, remains largely unknown. This study sets out to evaluate the molecular weight and polydispersity of the building blocks constituting the shell of poly(butyl cyanoacrylate) (PBCA) MB. Several different PBCA MB were synthesized, varying preparation parameters such as pH, surfactant, stirring speed, and stirring time. Using gel permeation chromatography, it is found that the number average molecular weight (M n ) of the polymer chains in the shell of PBCA MB is 4 kDa, and that >99% of the polymer chains are below 40 kDa. This demonstrates that virtually all polymeric building blocks in the shell of PBCA MB have a size which allows for renal excretion, thereby supporting their use for drug delivery applications.

Enhanced antitumoral activity of doxorubicin against lung cancer cells using biodegradable poly(butylcyanoacrylate) nanoparticles.

Doxorubicin (Dox) is widely used for the combined chemotherapy of solid tumors. However, the use of these drug associations in lung cancer has low antitumor efficacy. To improve its efficacious delivery and activity in lung adenocarcinoma cells, we developed a biodegradable and noncytotoxic nanoplatform based on biodegradable poly(butylcyanoacrylate) (PBCA). The reproducible formulation method was based on an anionic polymerization process of the PBCA monomer, with the antitumor drug being entrapped within the nanoparticle (NP) matrix during its formation. Improved drug-entrapment efficiencies and sustained (biphasic) drug-release properties were made possible by taking advantage of the synthesis conditions (drug, monomer, and surfactant-agent concentrations). Dox-loaded NPs significantly enhanced cellular uptake of the drug in the A549 and LL/2 lung cancer cell lines, leading to a significant improvement of the drug's antitumoral activity. In vivo studies demonstrated that Dox-loaded NPs clearly reduced tumor volumes and increased mouse-survival rates compared to the free drug. These results demonstrated that PBCA NPs may be used to optimize the antitumor activity of Dox, thus exhibiting a potential application in chemotherapy against lung adenocarcinoma.

Polybutylcyanoacrylate nanocarriers as promising targeted drug delivery systems.

Among the materials for preparing the polymeric nanocarriers, poly(n-butylcyanoacrylate) (PBCA), a polymer with medium length alkyl side chain, is of lower toxicity and proper degradation time. Therefore, PBCA has recently been regarded as a kind of widely used, biocompatible, biodegradable, low-toxic drug carrier. This review highlights the use of PBCA-based nanocarriers (PBCA-NCs) as targeting drug delivery systems and presents the methods of preparation, the surface modification and the advantages and limitations of PBCA-NCs. The drugs loaded in PBCA-NCs are summarized according to the treatment of diseases, and the different therapeutic applications and the most recent developments of PBCA-NCs are also discussed, which provides useful guidance on the targeting research of PBCA-NCs.

n-Butyl cyanoacrylate synthesis. A new quality step using microwaves.

Alkyl cyanoacrylates are interesting products for use in industry because of their properties enabling them to stick together a wide range of substrates. n-Butyl cyanoacrylate is one of the most successfully used tissue adhesives in the field of medicine because it exhibits bacteriostatic and haemostatic characteristics, in addition to its adhesive properties. At present, its synthesis is performed with good yields via Knoevenagel condensation using conventional sources of heating, but this requires a long processing time. The aim of this work was to look for a new way of synthesising n-butyl cyanoacrylate using microwave irradiation as the source of heating. This non-conventional source of heating most likely reduces the process time of the synthesis. In comparison with a conventional heating source, such as an oil bath, the results showed the advantages of this method whereby the n-butyl cyanoacrylate gave the same yield and quality with a reduction in the reaction time by a factor of 3-5-fold.

DNA amplification via polymerase chain reaction inside miniemulsion droplets with subsequent poly(n-butylcyanoacrylate) shell formation and delivery of polymeric capsules into mammalian cells.

There is a growing interest in the development of stable nanocapsules that could deliver the bioactive compounds within the living organism, and to release them without causing any toxic effects. Here the miniemulsion droplets were first used as "nanoreactors" for the amplification of single-molecule dsDNA template (476 and 790 base pairs) through PCR. Afterwards, each droplet was surrounded with a biodegradable PBCA shell by interfacial anionic polymerization, enabling therefore to deliver the PCR products into the cells. The size of the initial miniemulsion droplets and the final polymeric capsules was in the range of 250 and 320 nm, mainly depending on the type of the continuous phase and presence of dsDNA template molecules. The formation of PCR products was resolved with gel electrophoresis and detected with fluorescence spectroscopy in the presence of DNA specific dye (SYBRGreen). TEM studies were performed to prove the formation of the polymeric shell. The shell thickness was measured to be within 5-15 nm and the average molecular weight of the formed PBCA polymer was around 75000 g · mol(-1) . For the cell uptake experiments, the obtained nanocapsules were transferred from the organic phase into aqueous medium containing a water-soluble surfactant. The effect of the surfactant type (anionic, cationic or non-ionic) on the HeLa cell viability and nanocapsule uptake behavior was studied by CLSM and FACS. Confocal analysis demonstrated that nanocapsules stabilized with cationic (CTMA-Cl) and non-ionic (Lutensol AT50) surfactants show almost the same uptake, whereas capsules redispersed in anionic (SDS) surfactant possess a 30% higher uptake. The release of the encapsulated material within the cell was studied on the example of Cy5-labeled oligonucleotides showing the colocalization with mitochondria of MSCs cells.

Design, synthesis, and biological activities of novel 2-cyanoacrylates containing oxazole, oxadiazole, or quinoline moieties.

A series of novel 2-cyanoacrylates containing an oxazole, oxadiazole, or quinoline moiety were designed and synthesized, and their structures were characterized by (1)H NMR and elemental analysis (or high-resolution mass spectrometry). Their herbicidal activities against four weeds were evaluated, and the result indicated that some of the title compounds showed excellent herbicidal activities against rape and amaranth pigweed in postemergence treatment at a dose of 375 g/ha. Furthermore, most of these cyanoacrylates exhibited interesting plant growth regulatory activities.

Poly(alkylcyanoacrylate) colloidal particles as vehicles for antitumour drug delivery: a comparative study.

Because of the fundamental importance of new therapeutic routes for cancer treatment, a number of systems based on colloidal particles as vehicles for the delivery of chemotherapeutic agents have been devised. The target is always to provide the proper dose of the antitumour agent only at the desired locus of action, thus reducing the unwanted side effects. The systems studied in this work are nanospheres of the biodegradable polymers poly(ethyl-2-cyanoacrylate), poly(butylcyanoacrylate), poly(hexylcyanoacrylate) and poly(octylcyanoacrylate), all suitable for parenteral administration, as vehicles for 5-fluorouracil, a well studied drug used for the treatment of solid tumours. Two loading methods have been analyzed: the first one is based on drug addition during the process of generation of the particles, by an anionic emulsion/polymerization procedure, and the subsequent drug trapping in the polymeric network. The second method is based on surface adsorption in already formed nanoparticles, after incubation in the drug solution. A detailed investigation of the capabilities of the polymer particles to load this drug is described. The main factors determining the drug incorporation to the polymer network were the type of monomer, the pH and the drug concentration. The release kinetics of 5-fluorouracil is found to be controlled by the pH of the release medium, the type of drug incorporation and the type of polymer.

[Preparation of gemcitabine polybutylcyanoacrylate nanoparticles].

OBJECTIVE: To optimize the preparation process of gemcitabine polybutylcyanoacrylate nanoparticles (GCTB- PBCA-NP). METHODS: According to the particle size, the entrapment efficiency and the loading quantity of GCTB-PBCA-NP, single factor analysis was carried out to optimize the component composition and preparation process based on an orthogonal design. RESULTS: The mean particle size of the NP was (112-/+9) nm with an entrapment efficiency of (54.12-/+2.43)% and drug loading of (11.08-/+0.89)%. CONCLUSION: An optimized nanoparticular drug delivery system is obtained by emulsion polymerization.

Synthesis, antiviral and antifungal bioactivity of 2-cyano-acrylate derivatives containing phosphonyl moieties.

Alkyl 2-cyano-3-methylthio-3-phosphonylacrylates were synthesized by the reaction of alkyl 2-cyano-3,3-dimethylthioacrylates with dialkyl phosphites. The structures of the new compounds were characterized by elemental analyses, IR, 1H-, 13C- and 31P-NMR spectral data. These compounds were tested in vitro against pathogenic fungi, namely, Fusarium graminearum, Cytospora mandshurica and Fusarium oxysporum. Amongst all compounds, 2d and 2t were found to be effective against the tested fungi at 50 microg/mL. A half-leaf method was used to determine the in vivo protective, inactivation and curative efficacies of the title products against tobacco mosaic virus (TMV). Title compounds 2a and 2b were found to possess good in vivo curative, protection and inactivation effects against TMV with inhibitory rates at 500 mg/L of 60.0, 89.4 and 56.5 and 64.2, 84.2 and 61.2 %, respectively. To the best of our knowledge, this is the first report on the antiviral and antifungal activity of alkyl 2-cyano-3-methylthio-3-phosphonylacrylates.

Cellular uptake behavior of unfunctionalized and functionalized PBCA particles prepared in a miniemulsion.

Fluorescent dye labeled unfunctionalized and functionalized poly(n-butylcyanoacrylate) nanoparticles were prepared using a miniemulsion technique. Amino acid and methoxyPEG functionalization could be introduced by using aqueous solutions as an initiator for the anionic polymerization in the heterophase. All the particles prepared had sizes smaller than 250 nm and negative zeta-potentials. The molar mass distribution of the polymer was dependent on the acid used as the continuous phase and the initiator solution applied. Cells of three lines (HeLa, Jurkat and mesenchymal stem cells) were incubated with the particles. The molar mass of the polymer determined the onset and extent of apoptosis, and the total uptake was determined by the size and functionalization of the particles. Different uptake kinetics were obtained with HeLa and Jurkat cells after incubation with the same particle batch. The intracellular particle distribution, visualized by confocal laser scanning microscopy, did not show significant differences for either of the cell lines or particle batches.

Synthesis of high loading and encapsulation efficient paclitaxel-loaded poly(n-butyl cyanoacrylate) nanoparticles via miniemulsion.

The manufacture of stable paclitaxel-loaded poly(n-butyl cyanoacrylate) (PBCA) nanoparticles containing high loading and encapsulation efficiency simultaneously were achieved in the presence of pluronic F127 via miniemulsion. It was found that both drug loading and encapsulation efficiencies of PBCA nanoparticles prepared by miniemulsion were higher (approximately three times) than those obtained by emulsion with similar paclitaxel content in the feed monomer (1%, w/w). Furthermore, the loading and encapsulation efficiencies increased concurrently (to a maximum of 4 and 80%, respectively) with increasing paclitaxel content and these nanoparticles were spherical in shape and with size near 100 nm. XRD patterns revealed that paclitaxel in particles was distributed in the molecular or amorphous state or in the form of small crystals. The in vitro drug release profile of drug-loaded PBCA nanoparticles prepared from miniemulsion exhibited a gradual release; more than 80% (w/w) of the paclitaxel was released after 96 h.

Electron microscopic analysis of nanoparticles delivering thioflavin-T after intrahippocampal injection in mouse: implications for targeting beta-amyloid in Alzheimer's disease.

Prevention of beta-amyloid (Abeta) production, aggregation and formation of Abeta deposits is a key pharmacological target in Alzheimer's disease. The passage of Abeta-binding compounds through the blood-brain barrier is often hampered for free ligands, whereas it is enhanced by drug encapsulation in nanoparticles. Here, we describe the preparation and characterization of polymeric carriers containing thioflavin-T as a marker for fibrillar Abeta. This study is then focused on electron microscopic analyses of thioflavin-T after injection of thioflavin-T-containing nanoparticles into the mouse hippocampus. Therefore, the photoconversion of fluorescent thioflavin-T as model drug was performed in tissues fixed 3 days post-injection. Thioflavin-T delivered from nanospheres was predominantly found in neurons and microglia. Our data suggest that drugs delivered by nanoparticles might target Abeta in the brain.

Improved preparation and physical studies of polybutylcyanoacrylate nanocapsules.

An improved method for the preparation of alkylcyanoacrylate nanocapsules is proposed that involves the intermediate synthesis of a well defined adduct of a single monomer unit to an ethanol molecule. It leads to thinner capsule walls and, generally, to a more reproducible capsule structure. The chemical composition of the intermediate organic phase has been studied by nuclear magnetic resonance spectroscopy. The morphology and size of resulting structures is analysed, applying analytical ultracentrifugation and light microscopic particle tracking. The sizes of capsules prepared in the described manner depend on the concentrations of the oil and the monomer components, as is shown by the results of a set of experiments following a simple factorial design.

Study of the effect of polybutylcyanoacrylate nanoparticles and their metabolites on the primary immune response in mice to sheep red blood cells.

Polybutylcyanoacrylate nanoparticles (PBCN) and their metabolites (polycyanoacrylic acid--PCAA, and n-butanol) were compared with respect to their effects on the primary immune response of mice to sheep red blood cells (SRBC). PCAA was synthetized via a Knoevenagel reaction. Antibody production (hemagglutinins) and E-rosette-forming cells (E-RFC) were used to document the induction of antigen-specific immune response to SRBC in all immunized mice. PBCN showed a time- and dose-dependent effect on the immune response, both humoral and cellular. The inductive phase of immune response was affected preferably. The high dose of PBCN (200 mg kg(-1)) tended to suppress the immune response. This was expressed more in mice treated before antigenic stimulation. Lower dose (10 mgkg(-1)) stimulated the immune response. A significant difference was found in the effects of PBCN and their metabolites on the immune response. PCAA and n-butanol administered at doses equivalent (after lysosomal hydrolysis) to the doses applied of intact PBCN did not impair significantly the immune response. A clear time dependence and dose dependence were not observed. The study led to the hypothesis that the greater suppressive effect of PBCN, relative to either PCAA or n-butanol, or a mixture of them, is probably due to the blocking of the immunopresenting function of macrophages instead of some toxicity towards the immunocompetent cells.