PEGylated green halloysite/spinel ferrite nanocomposites for pH sensitive delivery of dexamethasone: A potential pulmonary drug delivery treatment option for COVID-19

Dexamethasone (Dex) is used in drug regimen for treatment of Coronavirus disease (COVID-19). Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) fusion and entry into the cell occurs at pH 5.5. In our present study, we have identified a green, cheap clay based halloysite (Hal) nanoformulation with release capability of Dex at such interactive pH condition. 30%ZnFe₂O₄/Hal and 30%NiFe₂O₄/Hal were prepared by one-pot synthesis technique. Dex (5% wt/wt) was functionalized over both nanocomposites. Finally, polyethylene glycol (PEG) was coated over ZnFe₂O₄/Hal/Dex and NiFe₂O₄/Hal/Dex nanocomposite using lyophilization technique (0.08 μl/mg of nanocarrier). The release ability of Dex was studied under pulmonary infection and normal pH conditions (pH = 5.6 and 7.4). The characterization study using X-ray diffraction (XRD) and UV-visible diffuse reflectance (DRS) spectra confirmed the presence of spinel ferrites over Hal. Nitrogen adsorption isotherm showed the surface area of ZnFe₂O₄/Hal (75 m²/g), pore volume (0.27 cm³/g) with average pore size (14.5 nm). Scanning electron microscope/Energy dispersive spectroscopy (SEM-EDS) and Transmission electron microscopy analysis revealed a textural change in halloysite tubular type indicating drug adsorption and PEG adhesion. DRS spectra indicated an intergrowth of zinc ferrite nanoparticles on the halloysite nanotubes. Interestingly, ZnFe₂O₄/Hal/Dex/PEG exhibited a high Dex release ability (17.5%, 168 h) at pH = 5.6 relevant to SARS-CoV-2 fusion entry into the cell pH condition of 5.5. Comparatively, the nanocomposite showed a less Dex release (<5%) release for 168 h at neutral pH = 7.4. The drug release kinetics were studied and the obtained data were fitted for the release constant and release exponent, using the Korsmeyer-Peppas model. To test the compatibility of our nanocomposites, we performed the cell viability assay (MTT) using HEK293 cells. Our results showed that at 0.3 mg/ml, Dex-loaded nanocomposite had a statistically significant improvement in cell viability compared to Dex alone. These results suggest that our nanocomposite has prevented the toxic effect of Dex and has huge potential to act as pulmonary drug delivery system for targeted lung infection therapeutics.

Synergistic action of curcumin and cisplatin on spinel ferrite/hierarchical MCM-41 nanocomposite against MCF-7, HeLa and HCT 116 cancer cell line

Background

Platinum-based drugs are widely used in cancer therapy, but are known for toxic side effects and resistance. Combinational drug delivery represents an effective chemotherapeutic strategy, but often leads to an increased toxicity. Aim of this study is to test the co-delivery of cisplatin with natural antioxidants on hierarchial porous large surface area hexagonal nanocarriers for synergistic action.

Results

A series of structured mesoporous materials were impregnated with magnetic spinel ferrite (30% CuFe2O4) and then coated with curcumin (25% wt/wt). Mesosilicalite and MCM-41 with high curcumin release abilities were functionalized with cisplatin (5% wt/wt) for synergistic effect of combinational drugs. The cytotoxic efficiency of our nanocomposites was tested on cell viability of MCF7 (human breast cancer), human cervical cancer (HeLa), colorectal cancer (HCT116), and HFF (human foreskin fibroblasts) cell lines using the MTT cell viability assay. At a concentration of 0.1 mg/ml, CuFe2O4/mesosilicalite/curcumin/cisplatin resulted in 89.53% reduction in viability in MCF7, 94.03% in HeLa, 64% in HCT116 and 87% in HFF; whereas, CuFe2O4/MCM-41/curcumin/cisplatin resulted in 76% reduction in viability in MCF7, 64.46% in HeLa, 64% in HCT116 and 24% in HFF. The EC50 for CuFe2O4/mesosilicalite/curcumin/cisplatin was 81.23 µg/ml in MCF7, 47.55 µg/ml in HeLa, 48.96 µg/ml in HCT116 and 76.83 µg/ml in HFF. The EC50 for CuFe2O4/MCM-41/curcumin/cisplatin was 72.51 µg/ml in MCF7, 58.6 µg/ml in HeLa, 62.58 µg/ml in HCT116 and 154.2 µg/ml in HFF. Furthermore, cells treated with both nanocomposites had a high number of cleaved Caspase 3-positive cells suggesting that the reduction in cell viability was triggered by activating the apoptotic signaling pathway.

Conclusion

Our results show that CuFe2O4/MCM-41/curcumin/cisplatin is a better candidate for combinational drug therapy due to its lowest EC50 value and the wider difference in EC50 (a fold change) between cancerous and non-cancerous cell line.