Fen Yu

Zn or O? An Atomic Level Comparison on Antibacterial Activities of Zinc Oxides.

For the first time, the influence of different types of atoms (Zn and O) on the antibacterial activities of nanosized ZnO was quantitatively evaluated with the aid of a 3D-printing-manufactured evaluation system. Two different outermost atomic layers were manufactured separately by using an ALD (atomic layer deposition) method. Interestingly, we found that each outermost atomic layer exhibited certain differences against gram-positive or gram-negative bacterial species. Zinc atoms as outermost layer (ZnO-Zn) showed a more pronounced antibacterial effect towards gram-negative E. coli (Escherichia coli), whereas oxygen atoms (ZnO-O) showed a stronger antibacterial activity against gram-positive S. aureus (Staphylococcus aureus). A possible antibacterial mechanism has been comprehensively discussed from different perspectives, including Zn(2+) concentrations, oxygen vacancies, photocatalytic activities and the DNA structural characteristics of different bacterial species.

Full Spectrum Visible LED Light Activated Antibacterial System Realized by Optimized Cu2O Crystals

Assisted by three-dimensional printing technology, we proposed and demonstrated a full spectrum visible light activated antibacterial system by using a combination of 500 nm sized Cu2O crystals and light-emitting diode (LED) lamps. Further improved antibacterial ratios were achieved, for the first time, with pure Cu2O for both Gram-positive bacteria and Gram-negative bacteria among all of the six different color LED lamps. For practical antibacterial applications, we revealed that the nonwoven fabric could act as excellent carrier for Cu2O crystals and provide impressive antibacterial performance. Furthermore, integrated with our self-developed app, the poly(ethylene terephthalate) film loaded with Cu2O crystals also showed significant antibacterial property, thus making it possible to be applied in field of touch screen. The present research not only provided a healthier alternative to traditional ultraviolet-based sterilization but also opened an auto-response manner to decrease the rate of microbial contamination on billions of touch screen devices.

Natural extracted aerogels with inherent anisotropy and their 3D printing assisted biomedical applications

Exemplified with jackfruit and sugarcane, natural extracted aerogels with inherent structural anisotropy were investigated for the first time. With the help of nano-modification, the dual liquid/current directing capability of the Ag decorated jackfruit aerogel was discovered. This interesting material was then applied as the core component of a 3D printed wearable device for intelligent wound management. The as-prepared ultra-light (<10 g) wearable device could provide drainage diversion, wound warning and triple antibacterial treatment in a continuous and automatic manner.

“The return of ceramic implants”: Rose stem inspired dual layered modification of ceramic scaffolds with improved mechanical and anti-infective properties

Nowadays, traditional ceramics for bone implants have considerably replaced by metal based biomedical materials, attributing to the friability of ceramics. However, ceramic implants possess excellent biocompatibility and longtime abrasion resistance. They should be more desirable for long-term uses of implants in case their fragility had been overcome. In the present work, inspired from natural rose, a dual-layer-modified ceramic scaffold was constructed by coating a superplastic layer of isocyanate (ISO) resin and a nano Zinc Oxide (nano-ZnO) layer on the ceramic scaffold. The ISO resin modification layer with 1 mm thickness, improved the mechanical properties of ceramic implants 2-3 times, and protect the ceramic implants from broken even drop from 1 m high. Moreover, such dual layered modification exhibited broad spectrum antibacterial behavior. In vivo biocompatible studies demonstrated that there was no obvious noticeable tissue damage in all major organs of mice after the implant surgeries.

NaCl: for the safer in vivo use of antibacterial silver based nanoparticles

Background As antibiotics progressively cease to be effective, silver based nanoparticles (SBNs), with broad antibacterial spectrum, might be the last line of defense against malicious bacteria. Unfortunately, there are still no proper SBNs-based strategies for in vivo antibacterial therapies. In this article, new carbon membrane packaged Ag nanoparticles (Ag-C) were synthesized. We assessed the effect of Ag-C with NaCl on size, cytotoxicity, antibacterial properties, metabolism and sepsis models. Methods The size of Ag-C with NaCl was accessed with UV-vis, TEM and SEM. Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa were used to illustrate the antibacterial properties of SBNs affected by NaCl. L929 and 3T3 cell lines were cultured in vitro; CCK-8 assay was used to test cytotoxicity. Then, we explored the metabolism of Ag-C with NaCl in vivo. Finally, the effect of Ag-C with 4× NaCl on sepsis was observed. Results NaCl could regulate the size of Ag-C. Ag-C exhibited superior antibacterial properties compared to similar sized pure Ag nanoparticles. Furthermore, the addition of NaCl could not only reduce the cytotoxicity of Ag-C, but could also continue to discharge Ag-C from major organs. Based on these factors, this method was used to treat a sepsis model (induced via cecal ligation and puncture), and it achieved satisfactory survival results. Conclusion This discovery, though still in its infancy, could significantly improve the safety and feasibility of SBNs and could potentially play an important role in modern in vivo antibacterial applications. Thus, a new method to combating the growing threat from drug-resistant bacteria could be possible. NaCl is the key to excretion of SBNs after in vivo antibacterial use.

3D printed self-driven thumb-sized motors for in-situ underwater pollutant remediation

Green fuel-driven thumb sized motors (TSM) were designed and optimized by 3D printing to explore their in-situ remediation applications in rare studied underwater area. Combined with areogel processing and specialized bacteria domestication, each tiny TSM could realize large area pollutant treatment precisely in an impressive half-automatically manner.