β-Cyclodextrin Stabilized Nanoceria for Hydrolytic Cleavage of Paraoxon in Aqueous and Cationic Micellar Media

Beta-cyclodextrin (β-CD) stabilized cerium oxide nanoparticles (β-CD@CeO₂ NPs) were synthesized through a hydrothermal route. The electronic properties, surface functional group, surface composition, size, and morphologies of the as-synthesized β-CD@CeO₂ NPs were characterized using UV-visible spectroscopy, FTIR analysis, high resolution X-ray photoelectron spectroscopy (HRXPS), high resolution transmission electron microscopy (HRTEM), and field emission scanning electron microscopy (FESEM). The pH-dependent variation of the ζ-potential of β-CD@CeO₂ NPs and the catalytic activity of the NPs for the hydrolysis of paraoxon were investigated. The observed pseudo-first-order rate constant (k_obs) for the hydrolysis of paraoxon is increased with increasing pH and the ζ-potential of β-CD@CeO₂ NPs. The kinetics and mechanism of hydrolysis of paraoxon in the aqueous and cationic micellar media have been discussed.

Cyclodextrin-Modified CeO2 Nanoparticles as a Multifunctional Nanozyme for Combinational Therapy of Psoriasis

Purpose

Reactive oxygen species (ROS)-induced oxidative stress plays a key role in the pathogenesis and progression of psoriasis by causing inflammation. Antioxidative strategies eradicating ROS may serve as effective and easy treatment options for psoriasis, while nanozymes with intrinsic antioxidant enzyme-like activity have not been explored for psoriasis treatment. The aim of this study is to fabricate β-cyclodextrins (β-CDs)-modified ceria nanoparticles (β-CDs/CeO₂ NPs) with drug-loaded and multimimic-enzyme activities for combinational psoriasis therapy.

Methods

The β-CDs/CeO₂ NPs were synthesized by a hydrothermal method using unmodified β-CDs as a protecting agent. The structure, size and morphology were analyzed by dynamic light scattering, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy. Considering the superoxide dismutase (SOD)- and catalase-mimetic activities, the in vitro antioxidant activity of the β-CDs/CeO2 NPs was investigated. After dithranol (DIT) was loaded, the drug-loading capacity and release profile were determined by UV-visible light spectrophotometer and high-performance liquid chromatography. The anti-psoriatic efficacy was studied in the imiquimod (IMQ)-induced mouse model on the basis of morphological evaluation, psoriasis area and severity index calculation (PASI), and inflammatory cytokine expression.

Results

The average particle size of the blank β-CDs/CeO₂ NPs was 60.89±0.32 nm with a polydispersity index (PDI) of 0.12, whereas that of the DIT-loaded NPs was 79.38±1.06 nm with a PDI of 0.27. TEM results showed the as-prepared NPs formed a uniform quasi-spherical shape with low polydispersity. XPS indicates synthesized NPs have a mixed Ce³⁺/Ce⁴⁺ valence state. FTIR spectroscopy confirmed the presence of β-CDs and DIT in the NPs. Inhibition of superoxide anion rate by NPs could be reached to 79.4% in the presence of 200 µg/mL, and elimination of H₂O₂ efficiency reached about 50% in the presence of 40 µg/mL, demonstrating excellent superoxide dismutase- and catalase-mimicking activities, thereby providing remarkable cryoprotection against ROS-mediated damage. Furthermore, β-CDs on the surface endowed the NPs with drug-loading function via host–guest interactions. The entrapment efficiency and drug loading of DIT are 94.7% and 3.48%, respectively. The in vitro drug release curves revealed a suitable release capability of DIT@β-CDs/CeO₂ NPs under physiological conditions. In IMQ-induced psoriatic model, the DIT@β-CDs/CeO₂ NPs exhibited excellent therapeutic effect.

Conclusion

This study may pave the way for the application of nanozyme β-CDs/CeO₂ NPs as a powerful tool for psoriasis therapy.