Georgi Yordanov

Entrapment of epirubicin in poly(butyl cyanoacrylate) colloidal nanospheres by nanoprecipitation: Formulation development and in vitro studies on cancer cell lines

This report describes the preparation of poly(butyl cyanoacrylate) nanospheres loaded with epirubicin by nanoprecipitation, their characterization and in vitro evaluation of the drug uptake and cytotoxicity on cancer cell lines. The epirubicin-loaded nanospheres were prepared by nanoprecipitation using presynthesized polymer and dextran 40 as a colloidal stabilizer at different pH and initial drug concentrations. The nanospheres were characterized for particle morphology, size distribution, zeta-potential and drug loading. Epirubicin-loaded particles with diameters around 350 nm were obtained. Drug loading depended on the pH and epirubicin concentration. Epirubicin was more cytotoxic when loaded in nanospheres. Drug release was studied by dialysis method. Cytotoxicity and drug uptake experiments were performed on HeLa and A549 cell lines. It was found that addition of polysorbate 80 could increase cytotoxicity. The cytotoxicity was found to correlate with the drug uptake by cells. The findings reported here demonstrate that epirubicin-loaded nanospheres of poly(butyl cyanoacrylate) can be successfully prepared by the nanoprecipitation approach as alternative to the well-known polymerization-based methods. It is found that the epirubicin-loaded nanospheres are more cytotoxic than the free drug to human carcinoma cell lines in vitro. The higher cytotoxicity of the obtained epirubicin formulations, compared with the free drug, is due to enhanced cellular internalization of epirubicin.

Colloidal formulations of etoposide based on poly(butyl cyanoacrylate) nanoparticles: preparation, physicochemical properties and cytotoxicity.

This article describes the preparation, physicochemical characterization and cytotoxicity assessment of novel colloidal formulations of etoposide based on poly(butyl cyanoacrylate) nanoparticles. Nanoparticles were prepared by controlled emulsion polymerization of butyl cyanoacrylate in aqueous medium using two different non-ionic colloidal stabilizers (pluronic F68 and polysorbate 80). The nanoparticles were spherical in shape, with average size ranging from 110-150 nm (empty nanoparticles) to 170-260 nm (drug-loaded nanoparticles), monomodal size distributions, and negative zeta-potentials at pH 7.4. Drug loading efficiency was around 63-68%. More than 80% of the drug was released from the formulations within 6-7h of dialysis experiments. Pluronic-coated nanoparticles possessed lower magnitude of the ζ-potentials (around -4 mV) in comparison with the polysorbate-coated ones (around -12 mV). All tested etoposide formulations induced apoptosis in adenocarcinoma human epithelial (A549) cells, as evident from condensation of chromatin and fragmentation of nuclei. It was found that etoposide formulated with poly(butyl cyanoacrylate) nanoparticles and polysorbate 80 exhibited the highest cytotoxicity toward adenocarcinoma cells.

Epirubicin loaded to pre-polymerized poly(butyl cyanoacrylate) nanoparticles: Preparation and in vitro evaluation in human lung adenocarcinoma cells

This article describes the preparation of epirubicin-loaded nanoparticles, prepared by loading of the drug in pre-polymerized poly(butyl cyanoacrylate) nanoparticles, their physicochemical characterization and in vitro evaluation on human lung adenocarcinoma (A549) cells. Nanoparticles were also coated in aqueous dispersions with two different non-ionic surfactants (Pluronic F68 and Polysorbate 80). All particles were spherical in shape, with monomodal size distributions. The zeta-potentials at pH 7.4 increased with augmentation of the particle drug content. The increased drug content was found to correlate with the initial concentration of the drug, used for the particle preparation. In vitro studies on A549 cells showed that the drug-loaded nanoparticles, as well as the combinations of free drug and empty nanoparticles, exhibited higher cytotoxicity than the free drug alone. The presence of surfactants also resulted in increased cytotoxicity. Fluorescent imaging of epirubicin internalization by the adenocarcinoma cells revealed that the free drug was predominantly localized in the cell nucleus, while a cytoplasmic localization was observed for the nanoparticle-bound drug formulations, suggesting the probability of nanoparticle endocytosis. Thus the hereby presented results could be useful for development of nanoparticle-based anthracycline formulations for treatment of lung adenocarcinoma.

Poly(ethyl cyanoacrylate) colloidal particles tagged with Rhodamine 6G: preparation and physicochemical characterization

AbstractThis paper describes the preparation and characterization of poly(ethyl cyanoacrylate) colloidal particles loaded with the organic fluorophore Rhodamine 6G. We studied the physicochemical properties of the colloidal particles: morphology, size-distribution, ζ-potential, fluorescent properties and photobleaching upon UV-light illumination. The properties of the obtained colloidal particles, as well as the dye loading efficiency, were found to depend on the concentrations of ethyl cyanoacrylate monomer and Rhodamine 6G in the polymerization medium. The fluorophore release from the colloidal particles in aqueous buffer is also studied.

Poly(n-butylcyanoacrylate) Submicron Particles Loaded with Ciprofloxacin for Potential Treatment of Bacterial Infections

Poly(n-butylcyanoacrylate) submicron colloidal particles loaded with the antibiotic ciprofloxacin are prepared by emulsion polymerization and characterized by scanning electron microscopy, dynamic light scattering, nuclear magnetic resonance and gel-permeation chromatography. The entrapment efficiency for ciprofloxacin in the polymer particles is investigated as a function of the monomer and drug concentrations in the polymerization medium. The kinetics of ciprofloxacin release from the polymer particles is found to depend on the pH of the release medium. Studies by gel-permeation chromatography indicate for a possible drug-polymer association. The antibacterial activity of the obtained formulation is tested on a clinical isolate of Escherichia coli bacterium and is found to be similar to that of the free drug.

Epirubicin loading in poly(butyl cyanoacrylate) nanoparticles manifests via altered intracellular localization and cellular response in cervical carcinoma (HeLa) cells

Abstract Objective: Drug loading into nanocarriers is used to facilitate drug delivery to target cells and organs. We have previously reported a change in cellular localization of epirubicin after loading to poly(butyl cyanoacrylate) (PBCA) nanoparticles. We aimed to further investigate the altered cellular localization and cellular responses to the described drug formulation. Materials and methods: HeLa cells were treated with epirubicin-loaded PBCA nanoparticles prepared by the pre-polymerization method. A systematic study was performed to evaluate the formulation cytotoxicity. Cellular localization and uptake of the formulation as well as cellular response to the treatment were evaluated. Results: Our studies revealed decreased cytotoxicity of the nanoparticle-formulated epirubicin compared to the free drug as well as a noticeable change in the drug’s intracellular localization. Epirubicin-loaded nanoparticles were internalized via endocytosis, accumulated inside endosomal vesicles and induced a two-fold stronger pro-apoptotic signal when compared to the free drug. The level of the tumor suppressor protein p53 in HeLa cells increased significantly upon treatment with free epirubicin, but remained relatively unchanged when cells were treated with equivalent dose of nanoparticle-loaded drug, suggesting a possible shift from p53-dependent DNA/RNA intercalation-based induction of cytotoxicity by free epirubicin to a caspase 3-induced cell death by the epirubicin-loaded PBCA formulation.

Development of cephalexin-loaded poly(ethyl cyanoacrylate) colloidal nanospheres

AbstractThis article considers the preparation and physicochemical characterization of a novel colloidal formulation of the β-lactam antibiotic cephalexin, loaded in poly(ethyl cyanoacrylate) colloidal nanospheres. The drug was loaded by means of drug incorporation in the interior of poly(ethyl cyanoacrylate) particles during the polymerization of the respective monomer in aqueous medium. The obtained colloids were characterized by scanning electron microscopy, dynamic and electrophoretic light scattering, Fourier transform infrared and nuclear magnetic resonance spectroscopy. It was found that the drug loading efficiency depends on the initial concentration of monomer and cephalexin in the polymerization medium. The average size of cephalexin-loaded particles was around 400 nm and did not depend significantly on the concentrations of drug and monomer. Drug-loaded particles with drug content as high as 21% (w/w) were prepared. The drug release kinetics was studied in physiological phosphate-buffered saline. It was found that a biexponential model could describe well the experimental release kinetics.

Poly(butyl cyanoacrylate) nanoparticles stabilised with poloxamer 188: particle size control and cytotoxic effects in cervical carcinoma (HeLa) cells

In this study, the preparation of poloxamer 188-coated poly(butyl cyanoacrylate) colloidal nanospheres of controlled size distribution and their physicochemical characterisation were investigated and their cytotoxic effects in cervical carcinoma (HeLa) cells evaluated. The nanoparticles were prepared by controlled emulsion polymerisation of butyl cyanoacrylate in an aqueous medium containing poloxamer 188 as an amphiphilic non-ionic colloidal stabiliser. The colloids thus obtained were characterised by scanning electron microscopy, dynamic and electrophoretic light-scattering, Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR) spectroscopy. The average size of the particles could be finely controlled within an interval between 220 nm and 290 nm by varying the concentration of the precursor and citric acid in the polymerisation medium. The particle zeta-potentials in phosphate-buffered saline were approximately −4.5 mV. FTIR and NMR data confirmed the expected composition of nanoparticles and the complete precursor polymerisation. In-vitro studies with cervical carcinoma (HeLa) cells demonstrated the dose-dependent cytotoxicity of nanoparticles (IC50 ≈ 30 εg mL−1). Observations by phase contrast and fluorescence microscopy revealed that at cytotoxic concentrations (40 εg mL−1) nanoparticles induced changes in cell morphology and chromatin fragmentation. The colloidal stabiliser (poloxamer 188) alone was not cytotoxic at the applied concentrations.