Functionalized graphene oxide-zinc oxide hybrid material and its deployment for adsorptive removal of levofloxacin from aqueous media.

This work reports on the synthesis of aspartic acid-functionalized graphene oxide-zinc oxide, as a functional porous material, and its potential to mitigate levofloxacin (LFXN). The adsorbent was characterized by various techniques, including ultraviolet-visible (UV-Vis), Fourier transform infrared (FT-IR) spectroscopy, powder X-ray diffraction (PXRD), and scanning electron microscopy (SEM). The average crystallite size of the prepared composite was about 17.30 nm. Batch adsorption studies were carried out to elucidate the adsorption process for LFXN. Different parameters, including contact time, LFXN initial concentration, adsorbent concentration, pH, temperature, and ionic strength were studied. The mechanism and kinetics were studied by fitting the data to Freundlich and Langmuir isotherms, pseudo-first-order and pseudo-second-order kinetic models, respectively. The isotherm data was better fitted to Langmuir isotherm (R2 = 0.999) as compared to the Freundlich model. The maximum adsorption capacity obtained at equilibrium was 73.15 mg/g. For kinetic studies, Pseudo first order was better fitted with R2 = 0.87797, confirming the physisorption process. Thermodynamics parameters revealed that the process was exothermic and spontaneous at low temperatures. The adsorption mechanism was studied and the impregnation of LFXN in the adsorbent was confirmed by FTIR studies. This research proved that the designed GO/Asp-ZnO was a novel and promising adsorbent for the removal of LFXN with an efficiency of 95.12% at 30 mg/L LFXN by 0.6 g/L adsorbent in 24 h at pH = 7 and T = 25 °C.

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 CuFe3O4, 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.