Bilayer wound dressing systems consisting of various biopolymers have been preferred in biomedical applications due to its enhanced advantages in comparison with conventional systems. The aim of this research was to develop a novel bilayer wound dressing based on gelatin (G) and gellan gum (GG). The bilayer was composed of an upper layer impregnated with antibiotic drug sodium ampicillin and a drug-free lower sponge layer. The bilayer hydrogels were characterized by FTIR, TGA, DSC and SEM analyses including swelling behaviors and hydrolytic degradation tests. To achieve faster healing of the wound by prevention of the bacterial infection, the bilayer hydrogels were developed as antibiotic-releasing vehicles. Herein, release study of sodium ampicillin was performed in PBS to simulate the physiological micro-environment. Additionally, cyto-compatibility tests of L929 fibroblast cells showed the high proliferation and survival through drug-loaded GG and G hydrogels (GG-G-D) after 24h, 48h and 72h incubation. This novel GG-G bilayer hydrogel could be a good candidate as wound dressing. Graphical abstract

This study aims to optimize the synthesis of semiconductor zirconia (ZrO2) nanoparticles for future photocatalytic applications in degradation of pollutants in wastewater under ultraviolet (UV) light. The synthesis procedure of ZrO2 nanoparticles was optimized by examining the effects of synthesis methods (ultrasound-assisted, hydrothermal method in an autoclave and conventional precipitation), reaction time (2, 6, 10, and 18 h), ambient pH (3, 7, 10, 13), and surfactant type (anionic, cationic, and non-ionic), on the particle size and crystal phase of the nanomaterial. The characterization of the synthesized samples was performed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy (EDS), high-contrast transmission electron microscopy (HR-TEM), and transmission electron microscope (TEM) analysis. Consequently, to synthesize ZrO2 nanoparticles with the smallest particle size and monoclinic/tetragonal phase, the experimental conditions were optimized as ultrasound-assisted synthesis method, pH 10, and 6 h reaction time without surfactant. Moreover, percentage yield, particle size, crystallinity, monoclinic and tetragonal volumes of ZrO2 nanostructures synthesized under optimized conditions were determined as 39.40%, approximately 9 nm, 46.77, 79%, and 21%, respectively. It has been determined that the particle sizes can be kept under control by controlling the phase composition of ZrO2 nanostructures by optimizing the synthesis parameters. Structural and morphological characterization results can be correlated to the photocatalytic application, showing the potential of this material for the photodegradation of organic dye pollutants.