Chitosan-based Dy2O3/CuFe3O4 bio-nanocomposite development, characterization, and drug release kinetics

Chitosan (CS)/metal oxide (MO) nano-carriers have recently attracted attention due to their great integration into several biomedical applications. Herein, CS and dysprosium oxide based bio-nanocomposites (Dy₂O₃/CuFe₃O₄/CS) were prepared using a citrate sol-gel route for biomedical settings at large and drug delivery, in particular. The chemical structure, average crystallite size, and surface morphology of Dy₂O₃/CuFe₃O₄/CS bio-nanocomposites were characterized using spectroscopic techniques, including FT-IR, PXRD, and SEM. The prepared nano composite's drug loading or release kinetics were investigated by FT-IR, zeta potential (ZP), and ultraviolet-visible spectroscopy (UV-Vis). In the FT-IR spectrum, the peaks in the range of 800-400 cm^-1 confirmed the formation of meta-oxides, while amide bands at 1661 and 1638 cm^-1 revealed the existence of CS in the bio-nanocomposite. The peaks at 2θ = 35.46 and 28.5, 39.4 indicated the presence and chemical interaction of Dy₂O₃ and CuFe₃O_4, respectively. The crystallite size was <20 nm. The model drug used in the loading and in vitro release assays was ciprofloxacin hydrochloride. Ciprofloxacin's CF stretch caused a modest peak to be seen at 1082 cm^-1 and changed in zeta potential value from 7.90 mV to 8.88 mV endorsing that the drug had been loaded onto the nanomaterial. The loading efficiency (%) of CIP onto the composite was from 25 to 30 %, calculated from optical density measurements. Different kinetic models, such as zero-order, first-order, Higuchi, Hixon-Crowell, and Korsmeyer-Peppas, were determined to confirm the drug release mechanism. The percent (%) of drug release from the surface of Dy₂O₃/CuFe₃O₄/CS in PBS (pH 7.4), acidic (pH 2.2) and basic (pH 9.4) dissolution media were found to be 70, 28 and 20 %, respectively. Drug kinetics showed that mainly the release is fickian type followed "Fick's law of diffusion", slightly deviated from fickian release (dissolution-dependent system). Korsmeyer-Peppas (R² 0.9773, n < 0.4) and Higuchi's (R² 0.9846) models were the best for fitting controlled drug release data. The results revealed that the Dy₂O₃/CuFe₃O₄/CS bio-nanocomposite has good potential for a controlled drug delivery system.

Investigation of the Antioxidant Properties of the Quaternized Chitosan Modified with a Gallic Acid Residue Using Peroxidase that Produces Reactive Oxygen Species

Chitosan modified with a (2-hydroxy-3-trimethylammonium) propyl group and gallic acid residue, or quaternized chitosan with gallic acid (QCG), was synthesized. Antioxidant properties of the produced QCG have been investigated. Peroxidase in combination with NADH and salicyl hydroxamate (SHAM) caused consumption of oxygen and production of H2O2 in aqueous solution as a result of O2 reduction in the peroxidase-oxidase reactions. The rates of O2 consumption and H2O2 generation were reduced in the presence of QCG. The antioxidant propyl gallate (PG) and superoxide dismutase (SOD) had the same effect, but not the quaternized chitosan (QC) without gallic acid. The effect of chitosan derivatives on the production of reactive oxygen species (ROS) in the cells of pea leaf epidermis and on the cell death detected by the destruction of cell nuclei, was investigated. QCG, QC, and SOD had no effect, while PG decreased the rate of ROS generation in the cells of the epidermis, which was induced by NADH with SHAM or by menadione. QCG and QC prevented destruction of the guard cell nuclei in the pea leaf epidermis that was caused by NADH with SHAM or by KCN. SOD had no effect on the destruction of nuclei, while the effect of PG depended on the inducer of the cell death. Suppression of the destruction of guard cell nuclei by chitosan derivatives was associated not with their antioxidant effect, but with the disruption of the plasma membrane of the cells. The results obtained have shown that QCG exhibits antioxidant properties in solutions, but does not prevent generation of ROS in the plant cells. The mechanism of antioxidant effect of QCG is similar to that of PG and SOD.

Liposomes-in-chitosan hydrogel boosts potential of chlorhexidine in biofilm eradication in vitro

Successful treatment of skin infections requires eradication of biofilms found in up to 90 % of all chronic wounds, causing delayed healing and increased morbidity. We hypothesized that chitosan hydrogel boosts the activity of liposomally-associated membrane active antimicrobials (MAA) and could potentially improve bacterial and biofilm eradication. Therefore, liposomes (∼300 nm) bearing chlorhexidine (CHX; ∼50 μg/mg lipid) as a model MAA were incorporated into chitosan hydrogel. The novel CHX-liposomes-in-hydrogel formulation was optimized for skin therapy. It significantly inhibited the production of nitric oxide (NO) in lipopolysaccharide (LPS)-induced macrophage and almost completely reduced biofilm formation. Moreover, it reduced Staphylococcus aureus and Pseudomonas aeruginosa adherent bacterial cells in biofilm by 64.2-98.1 %. Chitosan hydrogel boosted the anti-inflammatory and antimicrobial properties of CHX.