Ibrahima Youm

Entrapment and release kinetics of furosemide from pegylated nanocarriers.

This study was designed to test the hypothesis that furosemide (Fur) can be entrapped into surfactant free pegylated nanocarriers (NCs) for controlled drug release. To test this hypothesis, Fur-loaded NCs were prepared by emulsion solvent diffusion method. A 2(3) factorial design was used to optimize the effect of three formulation variables [amounts of Fur (X(1)), poly(lactic-co-glycolic acid) (X(2)) and poly-ε-caprolactone-polyethylene glycol (X(3))] on particle mean diameter (Y(1)), polydispersity index (PDI, Y(2)), and percent drug encapsulation efficiency (EE%, Y(3)). The NCs were characterized for morphology, thermal behavior, optical properties, crystallinity, and drug release kinetics using electron microscopy (EM), differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy, powder X-ray diffraction (PXRD), and high performance liquid chromatography, respectively. The optimum formula produced with 6 mg of Fur, 7 mg of PLGA, and 1mg of PCL-PEG corresponded to 183.26 nm, 0.26, and 88.29% as Y(1), Y(2) and Y(3) values, respectively. DSC thermograms, FTIR spectra and PXRD diffractograms indicated that Fur was encapsulated in its polymorphic crystalline form I within the NCs polymeric matrix. This was further confirmed by a comparative study between native Fur, Fur nanocrystal and Fur loaded NCs using scanning EM, PXRD and drug release kinetics. The release kinetics of the optimized formula fit the Higuchi model indicating that the drug was released by diffusion in 12h. These results indicate that pegylated Fur-loaded NCs could be successfully prepared with high EE% and sustained release profile intended for the inner ear drug delivery.

Resveratrol-loaded nanocarriers: Formulation, optimization, characterization and in vitro toxicity on cochlear cells

The present work aimed to investigate the suitability of polymeric nanoparticles (NPs) loaded with resveratrol (RES) for drug delivery to cochlear cells. RES-loaded NPs were prepared by a solvent-diffusion method without surfactant. The Box-Behnken design was used to study the effect of the formulation variables on the particle mean diameter (PMD), polydispersity index (PDI), zeta-potential (ζ), percent drug encapsulation efficiency (EE%), and ratio between NP size before and after freeze-drying (Sf/Si). The physicochemical stability of the RES-loaded NPs during freeze-drying was investigated using four well-known cryoprotectants (i.e., lactose, mannitol, sucrose, and trehalose) at different concentrations. The RES-loaded NPs were also characterized by powder X-ray diffraction (PXRD) and in vitro drug release studies. Finally, the in vitro toxicity of the synthesized NPs was evaluated on two cochlear cell lines: HEI-OC1 and SVK-1 cells. The optimal formulation (desirability: 0.86) had 135.5±37.3nm as PMD, 0.126±0.080 as PDI, -26.84±3.31mV as ζ, 99.83±17.59% as EE%, and 3.30±0.92 as Sf/Si ratio. The PMD and PDI of the RES-loaded NPs were maintained within the model space only when trehalose was used at concentrations higher than 15% (w/v). Results from the in vitro cytotoxicity studies showed that blank NPs did not alter the viability of both cells lines, except for concentrations higher than 600μg/mL. However, the cell viability was significantly decreased at high concentrations of native RES (>50μM, p<0.05) in both cell lines. Overall, the results suggested that the RES-loaded polymeric NPs could be a suitable template for cochlea antioxidant delivery and otoproctection.

Advances in Targeted Drug Delivery Approaches for the Central Nervous System Tumors: The Inspiration of Nanobiotechnology

At present, brain tumor is among the most challenging diseases to treat and the therapy is limited by the lack of effective methods to deliver anticancer agents across the blood-brain barrier (BBB). BBB is a selective barrier that separates the circulating blood from the brain extracellular fluid. In its neuroprotective function, BBB prevents the entry of toxins, as well as most of anticancer agents and is the main impediment for brain targeted drug delivery approaches. Nanotechnology-based delivery systems provide an attractive strategy to cross the BBB and reach the central nervous system (CNS). The incorporation of anticancer agents in various nanovehicles facilitates their delivery across the BBB. Moreover, a more powerful tool in brain tumor therapy has relied surface modifications of nanovehicles with specific ligands that can promote their passage through the BBB and favor the accumulation of the drug in CNS tumors. This review describes the physiological and anatomical features of the brain tumor and the BBB, and summarizes the recent advanced approaches to deliver anticancer drugs into brain tumor using nanobiotechnology-based drug carrier systems. The role of specific ligands in the design of functionalized nanovehicles for targeted delivery to brain tumor is reviewed. The current trends and future approaches in the CNS delivery of therapeutic molecules to tumors are also discussed.

Optimal Concentration of 2,2,2-Trichloroacetic Acid for Protein Precipitation Based on Response Surface Methodology.

For low protein concentrations containing biological samples (in proteomics) and for non proteinaceous compound assays (in bioanalysis), there is a critical need for a simple, fast, and cost-effective protein enrichment or precipitation method. However, 2,2,2-trichloroacetic acid (TCA) is traditionally used for protein precipitation at ineffective concentrations for very low protein containing samples. It is hypothesized that response surface methodology, can be used to systematically identify the optimal TCA concentration for protein precipitation in a wider concentration range. To test this hypothesis, a central composite design is used to assess the effects of two factors (X1 = volume of aqueous solution of protein, and X2 = volume of TCA solution 6.1N) on the optical absorbance of the supernatant (Y1), and the percentage of protein precipitated (Y2). Using either bovine serum albumin (BSA) as a model protein or human urine (with 20 ppm protein content), 4% w/v (a saddle point) is the optimal concentration of the TCA solution for protein precipitation that is visualized by SDS-PAGE analysis. At this optimal concentration, the Y2-values range from 76.26 to 92.67% w/w for 0.016 to 2 mg/mL of BSA solution. It is also useful for protein enrichment and xenobiotic analysis in protein-free supernatant as applied to tenofovir (a model HIV microbicide). In these conditions, the limit of detection and limit of quantitation of tenofovir are respectively 0.0014 mg/mL and 0.0042 mg/mL. This optimal concentration of TCA provides optimal condition for protein purification and analysis of any xenobiotic compound like tenofovir.

Validated Reverse-Phase High-Performance Liquid Chromatography for Quantification of Furosemide in Tablets and Nanoparticles

A simple, sensitive, and specific method for furosemide (FUR) analysis by reverse-phase-HPLC was developed using a Spherisorb C18 ODS 2 column. A chromatographic analysis was carried out using a mobile phase consisting of acetonitrile and 10 mM potassium phosphate buffer solution: 70 : 30 (v/v) at pH 3.85, at a flow rate of 1 mL·min−1. The UV-detection method was carried out at 233 nm at room temperature. Validation parameters including limit of detection (LOD), limit of quantitation (LOQ), linearity range, precision, accuracy, robustness, and specificity were investigated. Results indicated that the calibration curve was linear (r 2 = 0.9997) in the range of 5.2 to 25,000 ng·mL−1, with ε value equal to 3.74 × 104 L·M−1 ·cm−1. The LOD and LOQ were found to be 5.2 and 15.8 ng·mL−1, respectively. The developed method was found to be accurate (RSD less than 2%), precise, and specific with an intraday and interday RSD range of 1.233–1.509 and 1.615 to 1.963%. The stability of native FUR has also been performed in simulated perilymph and endolymph media (with respective potency in each medium of 99.8 ± 2.3% and 96.68 ± 0.7%, n = 3) after 6 hours. This method may be routinely used for the quantitative analysis of FUR from nanocarriers, USP tablets and release media related to hearing research