Pyrazinamide photodegradation on NiWO4-palygorskite nanocomposites under polychromatic irradiation.

In this work, antibiotic pyrazinamide (PZA) photodegradation on palygorskite (Pal), NiWO4 crystals, and NiWO4-Pal (2, 6, and 10%) nanocomposites was evaluated under polychromatic irradiation. In the characterization of the samples, XRD patterns displayed good crystallinity for NiWO4 crystals and nanocomposites. In addition, the diffractograms were used in the Rietveld refinement for phase indexing, revealing a wolframite-type monoclinic structure with the space group P2/c. The active vibrational modes related to the characteristic groups of the samples were identified using Raman and FTIR spectroscopy. Photoluminescence (PL) spectra revealed that NiWO4 and NiWO4-Pal (2%) nanocomposite have the highest electron-hole pair recombination rate, and the contribution of the green component in the NiWO4-Pal (2%) nanocomposite indicates a greater contribution of deep energy levels to the PL profile. DRS in the UV-visible region indicated that NiWO4 crystals have indirect band-gap energy (Egap) 2.64 eV; NiWO4-Pal (2, 6, and 10%) nanocomposites have 2.62, 2.58, and 2.59 eV, respectively; and Pal has 2.83 eV. The catalytic tests showed that the NiWO4-Pal (2%) nanocomposite samples, under polychromatic radiation, exhibit greater efficiency in photodegradation at 110 min, with yield of 98.5%. The ROS tests indicated that the studied reactive species play a similar role in PZA photodegradation.

Catalyst-Free Click Chemistry for Engineering Chondroitin Sulfate-Multiarmed PEG Hydrogels for Skin Tissue Engineering.

The quest for an ideal biomaterial perfectly matching the microenvironment of the surrounding tissues and cells is an endless challenge within biomedical research, in addition to integrating this with a facile and sustainable technology for its preparation. Engineering hydrogels through click chemistry would promote the sustainable invention of tailor-made hydrogels. Herein, we disclose a versatile and facile catalyst-free click chemistry for the generation of an innovative hydrogel by combining chondroitin sulfate (CS) and polyethylene glycol (PEG). Various multi-armed PEG-Norbornene (A-PEG-N) with different molecular sizes were investigated to generate crosslinked copolymers with tunable rheological and mechanical properties. The crosslinked and mechanically stable porous hydrogels could be generated by simply mixing the two clickable Tetrazine-CS (TCS) and A-PEG-N components, generating a self-standing hydrogel within minutes. The leading candidate (TCS-8A-PEG-N (40 kD)), based on the mechanical and biocompatibility results, was further employed as a scaffold to improve wound closure and blood flow in vivo. The hydrogel demonstrated not only enhanced blood perfusion and an increased number of blood vessels, but also desirable fibrous matrix orientation and normal collagen deposition. Taken together, these results demonstrate the potential of the hydrogel to improve wound repair and hold promise for in situ skin tissue engineering applications.

In vivo evaluation of bone repair guided with biological membrane based on polyhydroxybutyrate and norbixin.

The present work aimed to synthesize and verify the effectiveness of the polyhydroxybutyrate and norbixin membrane as a scaffold in bone defects induced in the tibia of rats. Twenty-four male Rattus norvegicus rats were used, divided into control and membrane groups. After anesthesia, a bone defect was induced in the right tibia, followed by the implantation of the biomaterial at the site of the lesion only in the membrane group, with euthanasia after 15 and 30 days of the experiment. The deposition of organic and inorganic matrix, the quality of newly formed bone tissue and the morphology of the bone defect were measured. After 15 days of the experiment, the biomaterial significantly influenced the deposition of hydroxyapatite crystals, the formation of collagen I matrix and mineralization content in relation to the control group, in addition to the abbreviation of the inflammatory process and superior quality of the newly formed bone tissue. After 30 days, only the membrane group had fully completed its repair process. The biomaterial acted as a scaffold in the regeneration of the guided bone defect by accelerating the synthesis of collagen matrix, mineralization content, density, and maturity when compared to the control group.