Structure and Property of Nano-TiO2 Doped with Ag+ Membrane Photocatalyst.

Highly transparent silver incorporated titania (Ag/TiO2) composite nanomembranes were fabricated by a simple, reproducible dip-coating process on ceramic substrates. The obtained membrane samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometer (EDX), X-ray photoelectron spectroscopy (XPS). The photocatalytic activity of the Ag/TiO2 nanomembranes was assessed by the degradation of methylene blue under visible light irradiation. Compared with pure TiO2 nanomembranes, no significant shift in the TiO2 crystal structure was detected after doping with silver ions. The results from the SEM and EDX analyses showed that homogeneous spherical silver nanoparticles were produced and scattered on the surface of the TiO2 nanomembrane that was coated on the surface of the ceramic substrates. The doping with silver ions could effectively improve the photocatalytic activity of TiO2 under visible light irradiation. The Ag/TiO2 composite nanomembrane also exhibited improved hydrophilicity compared to that of a pure TiO2 nanomembrane.

Synergistic effects of Fe-based nanomaterial catalyst on humic substances formation and microplastics mitigation during sewage sludge composting.

In this study, a novel Fe-based nanomaterial catalyst (Fe0/FeS) was synthesized via a self-heating process and employed to explore its impact on the formation of humic substances and the mitigation of microplastics. The results reveal that Fe0/FeS exhibited a significant increase in humic acid content (71.01 mg kg-1). Similarly, the formation of humic substances resulted in a higher humification index (4.91). Moreover, the addition of Fe0/FeS accelerated the degradation of microplastics (MPs), resulting in a lower concentration of MPs (9487 particles/kg) compared to the control experiments (22792 particles/kg). Fe0/FeS significantly increased the abundance of medium-sized MPs (50-200 µm) and reduced the abundance of small-sized (10-50 µm) and large-sized MPs (>1000 µm). These results can be attributed to the Fe0/FeS regulating the ▪OH production and specific microorganisms to promote humic substance formation and the degradation of MPs. This study proposes a feasible strategy to improve composting characteristics and reduce contaminants.

Recycling of waste crab shells into reinforced poly (lactic acid) biocomposites for 3D printing.

To promote natural waste resource utilization, a novel biocomposite, composed of waste crab shells and poly (lactic acid) matrix, was developed by combining chemical treatment and 3D printing. A crab shell powder (ISCSP) with an abundant porous structure and a high specific surface area was obtained by treatment with hydrochloric acid and sodium hydroxide. Importantly, under the optimal printing parameters determined by the finite element analysis, test samples, and porous bones were successfully printed using CSP/PLA composites by a commercial fused deposition modeling (FDM) 3D printer. The morphology, mechanical and thermal properties, antibacterial properties, and biocompatibility of the CSP/PLA composites were then assessed. Our results revealed that the tensile strength and flexural strength of the ISCSP/PLA composites reached 58.71 and 90.11 MPa, which were 28.6 % and 28.8 % higher than that of pure PLA, respectively. The glass transition and melting temperatures of the composites remained similar to those of pure PLA. Interestingly, the addition of CSP increased PLA crystallinity, which could be attributed to the nucleation effect of CSP in the system. The antibacterial activity of the PLA-1.5ESCSP composite samples against Escherichia coli (E. coli) was greater than 99 %. More importantly, the live/dead assay showed that the CSP/PLA composites possessed excellent biocompatibility. Therefore, the developed CSP/PLA biocomposites are potential feedstocks for 3D printing in bone tissue engineering and may be used as graft substitutes in reparative and reconstructive surgery. They are especially beneficial due to their superior mechanical and thermal properties, excellent antibacterial activities, and significant biocompatibility.

"Sandwich-like" structure electrostatic spun micro/nanofiber polylactic acid-polyvinyl alcohol-polylactic acid film dressing with metformin hydrochloride and puerarin for enhanced diabetic wound healing.

A diabetic wound is a typical chronic wound with a long repair process and poor healing effects. It is an effective way to promote diabetic wound healing to design electrospinning nanofiber films with drug-assisted therapy, good air permeability and, a multilayer functional structure. In this paper, a diabetic wound dressing with a "sandwich-like" structure was designed. Metformin hydrochloride, loaded in the hydrophilic PVA inner layer, could effectively promote diabetic wound healing. The drug release was slowed down by osmosis. The laminate film dressing had good mechanical properties, with tensile strength and elongation at break reaching 5.91 MPa and 90.47 %, respectively, which was close to human skin. The laminate film loaded with erythromycin and puerarin in the hydrophobic PLA outer layer had good antibacterial properties. In addition, due to the high specific surface of the electrostatic spun film, it exhibited high water vapor permeability. It facilitates the gas exchange between the wound and the outside world. The cell experiments proved that the laminate film dressing had good biocompatibility. There was no toxic side effect on cell proliferation. In the diabetic animal wound model, it was shown that the closure rate of diabetic wound repair by laminate film reached 91.11 % in the second week. Our results suggest that the "sandwich-like" nanofiber film dressing could effectively promote the healing process and meet the various requirements of diabetic wound dressing as a promising candidate for future clinical application of chronic wound dressings.

Electrospun polylactic acid nanofiber film modified by silver oxide deposited on hemp fibers for antibacterial fruit packaging.

Bacterial and fungal contamination have become major factors in fruit spoilage and damage, posing a potential risk to human health. In this work, polylactic acid (PLA) nanofibers combined with Ag2O-hemp fibers for a good antimicrobial effect were developed and applied to antimicrobial fruit fresh-keeping packages. The results of molecular simulation calculations showed that the strength of hydrogen bonds between Ag2O and hemp fibers reached 45.522 kJ·mol-1, which proved that Ag2O and with hemp fibers formed a stable deposition. The Ag2O-hemp fibers modified electrospun polylactic acid nanofibrous composite film exhibited favorable mechanical properties. The tensile strength reached 5.23 ± 0.05 MPa and the elongation at break reached 105.56 ± 3.95 %. The obtained nanofibrous composite film has good antibacterial activity against E. coli, S. aureus, A. niger, and Penicillium, which indicated that they could effectively inhibit the growth of bacteria and fungi. The cell experiments proved that the nanofibrous composite film had good biocompatibility with a cell survival rate of 100 %. The experimental results on the fresh-keeping of red grapes showed that the PLA nanofibrous composite film modified by the Ag2O-hemp fibers could effectively prolong the spoilage time of red grapes at room temperature. Compared with the blank group, the freshness period of PLA nanofiber film modified by Ag2O-hemp fibers could be extended for more than 5 days. The hardness of 15 days (1.94 ± 0.19 × 105 Pa) was basically the same as that of 1 day (2.05 ± 0.06 × 105 Pa). The results were superior to commercially available PE preservation films. The above research results indicated that the Ag2O-hemp fibers modified PLA nanofibrous composite film had potential application prospects in the field of fruit fresh-keeping package.

Zirconia toughened hydroxyapatite biocomposite formed by a DLP 3D printing process for potential bone tissue engineering.

The construction of ceramic components with UV curing is a developing trend by an additive manufacturing (AM) technology, due to the excellent advantages of high precision selective fixation and rapid prototyping, the application of this technology to bone defect repair had become one of the hotspots of research. Hydroxyapatite (HAP) is one of the most popular calcium phosphate biomaterials, which is very close to the main ingredient of human bones. Thus, hydroxyapatite biomaterials are popular as bone graft materials. In summary, the preparation of HAP bioceramics by a 3D printing of digital light processing (DLP) is a promising work. However, the preparation of HAP hybrid suspensions with high solid loading and good fluidity that can be printed by DLP encountered some challenges. Therefore, the purpose of this work is to improve and develop a novel UV-curing suspension with a high solids loading, which the suspension with the hydrodynamic properties and stability are suitable for DLP printer, in order to compensate for the brittleness of HAP ceramics itself to a certain extent, a low amount of zirconia was added in the suspension as an additive to fabricate a zirconia toughened HAP bioceramic composite by a DLP of 3D printing. In this work, the HAP powder was pre-modified by two organic modifiers to improve the compatibility in the acrylic resin system, and the addition of the castor oil phosphate further reduced the shear stress of the suspension to ensure strong liquidity. The UV suspension with 60 wt% powder particle loading had a minimum viscosity of 7495 mPa·s at 30 rpm, which was vacuum sintered at 1100 °C, 1200 °C, and 1250 °C, respectively. The composite ceramics (with 6 wt% ZrO2) at 1200 °C had a relative density of 90.7%, while the sintered samples at 1250 °C had stronger tensile strength and bending strength. The toughening effect of zirconia incorporation on HAP ceramics was also confirmed by the change of tensile modulus and bending modulus, whereas the corresponding mechanical properties were also significantly enhanced.

Facile fabrication of poly(L-lactic acid) microsphere-incorporated calcium alginate/hydroxyapatite porous scaffolds based on Pickering emulsion templates.

In this study, we develop a facile one-pot approach to the fabrication of poly(L-lactic acid) (PLLA) microsphere-incorporated calcium alginate (ALG-Ca)/hydroxyapatite (HAp) porous scaffolds based on HAp nanoparticle-stabilized oil-in-water Pickering emulsion templates, which contain alginate in the aqueous phase and PLLA in the oil phase. The emulsion aqueous phase is solidified by in situ gelation of alginate with Ca(2+) released from HAp by decreasing pH with slow hydrolysis of D-gluconic acid δ-lactone (GDL) to produce emulsion droplet-incorporated gels, followed by freeze-drying to form porous scaffolds containing microspheres. The pore structure of porous scaffolds can be adjusted by varying the HAp or GDL concentration. The compressive tests show that the increase of HAp or GDL concentration is beneficial to improve the compressive property of porous scaffolds, while the excessive HAp can lead to the decrease in compressive property. Moreover, the swelling behavior studies display that the swelling ratios of porous scaffolds reduce with increasing HAp or GDL concentration. Furthermore, hydrophobic drug ibuprofen (IBU) and hydrophilic drug bovine serum albumin (BSA) are loaded into the microspheres and scaffold matrix, respectively. In vitro drug release results indicate that BSA has a rapid release while IBU has a sustained release in the dual drug-loaded scaffolds. In vitro cell culture experiments verify that mouse bone mesenchymal stem cells can proliferate on the porous scaffolds well, indicating the good biocompatibility of porous scaffolds. All these results demonstrate that the PLLA microsphere-incorporated ALG-Ca/HAp porous scaffolds have a promising potential for tissue engineering and drug delivery applications.

One-step synthesis of magnetic hollow mesoporous silica (MHMS) nanospheres for drug delivery nanosystems via electrostatic self-assembly templated approach.

In this work, yolk-shell structured magnetic hollow mesoporous silica (MHMS) nanospheres with controllable magnetic responsibility, high specific surface area, a huge cavity and ink-bottle type mesopores were successfully synthesized in one-step by an electrostatic self-assembly templated approach. The obtained MHMS nanospheres exhibited low cytotoxicity, excellent biocompatibility and potential application in the biomedical field.

Electrospinning polyvinylidene fluoride fibrous membranes containing anti-bacterial drugs used as wound dressing.

The aim of this study was to synthesis drug-loaded fibrous membrane scaffolds for potential applications as wound dressing. Polyvinylidene fluoride (PVDF) fibrous membranes were loaded with enrofloxacin (Enro) drugs by using an electrospinning process, and their mechanical strength, drug release profile and anti-bacterial properties were evaluated. Enro drug-loaded PVDF membranes exhibited good elasticity, flexibility and excellent mechanical strength. The electrospinning Enro/PVDF membranes showed a burst drug release in the initial 12h, followed by sustained release for the next 3 days, which was an essential property for antibiotic drugs applied for wound healing. The drug-loaded PVDF fibrous membranes displayed excellent anti-bacterial activity toward Escherichia coli and Staphylococcus aureus. The results suggest that electrospinning PVDF membrane scaffolds loaded with drugs can be used as wound dressing.