الفهرس 
General introductionOnly 14 pages are availabe for public view
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Abstract
Gelatin has many merits that encourage its use in the pulmonary delivery of anticancer drugs. It is a biodegradable and biocompatible polyampholyte which possesses several modifiable functional groups. In addition, gelatin has balanced anionic, cationic and hydrophobic characters that facilitate loading of chemotherapeutic agents. Hence, the purpose of the study was to formulate biodegradable and low-antigenic particulate carrier as gelatin nanoparticles (GNPs) for the efficient pulmonary delivery of methotrexate (MTX) for lung cancer treatment.
GNPs were prepared implying the double desolvation method. The fabrication process was optimized using Box-Behnken design (BBD) of experiments to obtain GNPs with targeted PS. A comparative study on the uptake of GNPs by the A549 cells and macrophages was implemented using flow cytometry. Results showed a preferential uptake of the nanoparticles (NPs) by A549 cells in comparison to macrophages as suggested by cellular fluorescence and granularity increment following cells treatment with the optimized NPs.
MTX was loaded in GNPs using three different techniques: encapsulation, post loading and chemical conjugation. characterization of effect of the loading technique on the NPs in terms of particle size (PS), zeta potential (ζ) and loading efficiency was performed. Moreover, release profiles were followed and cytotoxicity assays on A549 lung cancer cells were performed for the optimized NPs. The results showed that encapsulation, post loading and chemical conjugation could load MTX in GNPs with the respective drug loadings 4.1 ± 0.39, 96 ± 3.41 and 84.6 ± 0.23 μg/mg of NPs. Post loaded NPs released 43.25 ± 3.40 % of MTX during the first 8 h and exhibited a sustained release for 36 h with MTX release of 53.35 ± 4.30%. Enhancement of drug release was obsereved upon trypsin addition where 98.60 ± 1.10 % of MTX was released over 36 h. On the other hand, 34.99±2.66% of MTX was released to the recipient compartment only following trypsin addition from chemically conjugated NPs during 48 h. Furthermore, MTX chemically conjugated NPs demonstrated up to four fold significant reduction in MTX IC50.
To allow for passive lung targeting using a dry powder inhaler, nanocomposite microparticles or nano-in-microparticles (NIMs) systems were prepared by co-spray drying the selected NPs formulation with leucine. characterization of the spray-dried NIMs was accomplished using differential scanning calorimetry (DSC), X-ray powder diffraction (XRPD) and scanning electron microscopy (SEM). Furthermore, in vitro lung deposition for spray-dried NIMs was implemented using next generation impactor. DSC thermograms and XRPD figures suggested powder amorphization upon spray drying (SD). SEM images for the prepared NIMs formulation revealed its doughnut shape with a rough outer surface. Additionally, the selected spray dried NIMs formulation demonstrated a high fine particle fraction (FPF%) of 49.53 ± 2.10% with a mass median aerodynamic diameter of 2.5 ± 0.13 μm when tested with the impactor.
As a conclusion, GNPs chemically conjugated with MTX could preferentially accumulate in lung cancer cells boosting the cytotoxic activity of the chemotherapeutic agent. The spray dried gelatin NIMs demonstrated good aerosolization properties enabling deep lung deposition providing thus a promising platform for lung cancer therapy.
Keywords:
Gelatin, Pulmonary delivery, Nanoparticles, Methotrexate, Lung cancer, Spray drying, Dry powder inhalation, Nanocomposite microcarriers .