Transferrin-Conjugated Docetaxel-PLGA Nanoparticles for Tumor Targeting: Influence on MCF-7 Cell Cycle

Targeted drug delivery systems are commonly used to improve the therapeutic index of anti-cancer drugs by increasing their selectivity and reducing systemic distribution and toxicity. Ligand-conjugated nanoparticles (NPs) can be effectively applied for active chemotherapeutic targeting to overexpressed receptors of tumor cells. In this study, transferrin (Tf) was successfully conjugated with poly-l-lactic-co-glycolic acid (PLGA) using ethylene diamine confirmed by NMR, for the loading of docetaxel trihydrate (DCT) into PLGA nanoparticles (NPs). The DCT-loaded Tf-conjugated PLGA NPs were produced by an emulsion-solvent evaporation technique, and a 3² full factorial design was used to optimize the nanoparticle formulations. The DCT-loaded Tf-conjugated PLGA NPs were characterized by FTIR spectroscopy, differential scanning calorimetry, powder X-ray diffraction (PXRD), TEM, particle size, and zeta potential analysis. In vitro release kinetics confirmed that release of DCT from the designed formulations followed a zero-order kinetics and a diffusion controlled non-Fickian release profile. The DCT-loaded Tf-conjugated PLGA NPs were evaluated in vitro in MCF-7 cells for bioactivity assessment. Cytotoxicity studies confirmed that the Tf-conjugated PLGA NPs were more active than the non-conjugated counterparts. Cell uptake studies re-confirmed the ligand-mediated active targeting of the formulated NPs. From the cell cycle analysis, the anti-cancer activity of DCT-loaded Tf-conjugated PLGA NPs was shown to occur by arresting the G₂/M phase.

Predictive modeling of insulin release profile from cross-linked chitosan microspheres

Insulin-loaded microspheres composed of chitosan 3% (w/v), and loading 120 IU insulin were produced by emulsion cross-linking method. Cross-linking time was 5 h and glutaraldehyde 3.5% (v/v) was used as cross-linker. Swelling ratio studies were evaluated to predict release of insulin from chitosan microspheres. Bacitracin and sodium taurocholate were incorporated in the formulations as proteolytic enzyme inhibitor and absorption enhancer, respectively. In vitro insulin release studies were performed in phosphate buffer pH 7.4 and also in HCl pH 2 with and without trypsin. Activity of bacitracin was also evaluated. In vitro release showed a controlled profile up to 12 h and the formulation containing 0.15% (w/v) of bacitracin revealed a maximum biological activity of about 49.1 ± 4.1%. Mathematical modeling using Higuchi and Korsmeyer-Peppas suggested a non-Fickian diffusion as the mechanism of insulin release. Insulin-loaded chitosan microspheres for oral delivery showed to be an innovative and reliable delivery system to overcome conventional insulin therapy.

Thermo-sensitive gels containing lorazepam microspheres for intranasal brain targeting

Thermo-sensitive gels containing lorazepam microspheres were developed and characterized for intranasal brain targeting. Pluronics (PF-127 and PF-68) have been selected since they are thermo-reversible polymers with the property of forming a solution at low temperatures (4-5 °C), and a gel at body temperature (37 °C). This property makes them an interesting material to work with, especially in case of controlled release formulations. The present study focuses on the development of an intranasal formulation for lorazepam, as an alternative route of drug delivery to the brain. Direct transport of drugs to the brain circumventing the brain barrier, following intranasal administration, provides a unique feature and better option to target brain. The presence of mucoadhesive microspheres in the gel vehicle via nasal route can achieve a dual purpose of prolonged drug release and enhanced bioavailability. To optimise the microsphere formulation, Box Behnken design was employed by investigating the effect of three factors, polymer concentration (chitosan), emulsifier concentration (Span 80) and cross-linking agent (glutaraldehyde) on the response variable which is the mean particle size. The concentration of 21% PF-127 and 1% PF-68 were found to be promising gel vehicles. The results showed that the release rate followed a prolonged profile dispersion of the microspheres in the viscous media, in comparison to the microspheres alone. Histopathological studies proved that the optimised formulation does not produce any toxic effect on the microscopic structure of nasal mucosa.

Cross-linked chitosan microspheres for oral delivery of insulin: Taguchi design and in vivo testing

Insulin-loaded chitosan microspheres were engineered by emulsion cross-linking method using glutaraldehyde as cross-linker. Taguchi orthogonal method was applied to optimize the production time and reduce the number of experiments required to obtain an optimized formulation. Three variables were evaluated, i.e. chitosan and glutaraldehyde concentrations, and cross-linking time at three levels. The dependent variables were the mean particle size and the encapsulation efficiency. The optimal formulation was obtained with chitosan 3% (w/v), glutaraldehyde 3.5% (v/v), and cross-linking time of 5h, characterized by microspheres with a mean particle size of 29.5 μm, and insulin encapsulation efficiency of 71.6±1.3%. In vivo studies were carried out using male Wistar albino rats, revealing a significant reduction in blood glucose level after administration of the optimized formulation, in comparison to a subcutaneous insulin injection. Chitosan microspheres were superior in terms of sustaining protein release over conventional insulin therapy.