Antimicrobial and cleaning effects of ultrasonic-mediated plasma-loaded microbubbles on Enterococcus faecalis biofilm: an in vitro study.

BACKGROUND: Enterococcus faecalis (E. faecalis) is the most frequently isolated bacteria from teeth with root canal treatment failure. This study aims to evaluate the disinfection effect of ultrasonic-mediated cold plasma-loaded microbubbles (PMBs) on 7d E. faecalis biofilm, the mechanical safety and the mechanisms. METHODS: The PMBs were fabricated by a modified emulsification process and the key reactive species, nitric oxide (NO) and hydrogen peroxide (H2O2) were evaluated. The 7d E. faecalis biofilm on human tooth disk was constructed and divided into the following groups: PBS, 2.5%NaOCl, 2%CHX, and different concentrations of PMBs (108 mL-1, 107 mL-1). The disinfection effects and elimination effects were verified with confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). Microhardness and roughness change of dentin after PMBs treatment were verified respectively. RESULTS: The concentration of NO and H2O2 in PMBs increased by 39.99% and 50.97% after ultrasound treatment (p < 0.05) respectively. The CLSM and SEM results indicate that PMBs with ultrasound treatment could remove the bacteria and biofilm components effectively, especially those living in dentin tubules. The 2.5% NaOCl presented an excellent effect against biofilm on dishes, but the elimination effect on dentin tubules is limited. The 2% CHX group exhibits significant disinfection effect. The biosafety tests indicated that there is no significant changes on microhardness and roughness after PMBs with ultrasound treatment (p > 0.05). CONCLUSION: PMBs combined with ultrasound treatment exhibited significant disinfection effect and biofilm removal effect, the mechanical safety is acceptable.

Bean Pod-Like SbSn/N-Doped Carbon Fibers toward a Binder Free, Free-Standing, and High-Performance Anode for Sodium-Ion Batteries.

Bimetallic SbSn alloy stands out among the anode materials for sodium-ion batteries (SIBs) because of its high theoretical specific capacity (752 mAh g-1 ) and good electrical conductivity. However, the major challenge is the large volume change during cycling processes, bringing about rapid capacity decay. Herein, to cope with this issue, through electrostatic spinning and high temperature calcination reduction, the unique bean pod-like free-standing membrane is designed initially, filling SbSn dots into integrated carbon matrix including hollow carbon spheres and nitrogen-doped carbon fibers (B-SbSn/NCFs). Significantly, the synergistic carbon matrix not only improves the conductivity and flexibility, but provides enough buffer space to alleviate the large volume change of metal particles. More importantly, the B-SbSn/NCFs free-standing membrane can be directly used as the anode without polymer binder and conductive agent, which improves the energy density and reaction kinetics. Satisfyingly, the free-standing BSbSn/NCFs membrane anode shows excellent electrochemical performance in SIB. The specific capacity of the membrane electrode can maintain 486.9 mAh g-1 and the coulombic efficiency is close to 100% after 400 cycles at 100 mA g-1 . Furthermore, the full cell based on B-SbSn/NCFs anode also exhibits the good electrochemical performance.

Label-free sensitive electrogenerated chemiluminescence aptasensing based on chitosan/Ru(bpy)3²âº/silica nanoparticles modified electrode.

In this work, a label-free and sensitive electrogenerated chemiluminescence (ECL) aptasensing scheme for K(+) was developed based on G-rich DNA aptamer and chitosan/Ru(bpy)3(2+)/silica (CRuS) nanoparticles (NPs)-modified glass carbon electrode. This ECL aptasensing approach has benefited from the observation that the G-rich DNA aptamer at the unfolded state showed more ECL enhancing signal at CRuS NPs-modified electrode than the binding state with K(+), which folds into G-quadruplex structure. As such, the decreasing ECL signals could be used to detect K(+). Compared to other aptasensing K(+) approaches previously reported, the proposed ECL sensing scheme is a label-free aptasensing strategy, which eliminates the labeling, separation, and immobilization steps, and behaves in a simple, low-cost way. More importantly, because the proposed ECL sensing mechanism utilizes the nanosized ECL active CRuS NPs to sense the nanoscale conformation change from the aptamer binding to target, it is specific. In addition, due to the great conformation changes of the aptamer's G-bases on CRuS NPs and the excellent ECL enhancing effect of guanine bases to the Ru(bpy)3(2+) ECL reaction, a 0.3 nM detection limit for K(+) was achieved with the proposed ECL method. On the basis of these advantages, the proposed ECL aptasensing method was also successfully used to detect K(+) in colorectal cancer cells.

Effects of the Biomimetic Microstructure in Electrospun Fiber Sutures and Mechanical Tension on Tissue Repair.

Electrospun microfibers, designed to emulate the extracellular matrix (ECM), play a crucial role in regulating the cellular microenvironment for tissue repair. Understanding their mechanical influence and inherent biological interactions at the ECM interface, however, remains a complex challenge. This study delves into the role of mechanical cues in tissue repair by fabricating Col/PLCL microfibers with varying chemical compositions and alignments that mimic the structure of the ECM. Furthermore, we optimized these microfibers to create the Col/PLCL@PDO aligned suture, with a specific emphasis on mechanical tension in tissue repair. The result reveals that within fibers of identical chemical composition, fibroblast proliferation is more pronounced in aligned fibers than in unaligned ones. Moreover, cells on aligned fibers exhibit an increased aspect ratio. In vivo experiments demonstrated that as the tension increased to a certain level, cell proliferation augmented, cells assumed more elongated morphologies with distinct protrusions, and there was an elevated secretion of collagen III and tension suture, facilitating soft tissue repair. This research illuminates the structural and mechanical dynamics of electrospun fiber scaffolds; it will provide crucial insights for the advancement of precise and controllable tissue engineering materials.

Ultrasound-Activated Nanodroplet Disruption of the Enterococcus faecalis Biofilm in Dental Root Canal.

Conventional methods used to control bacterial biofilm infection in root canals have poor efficacy, causing repeated and chronic infections, which pose a great challenge to clinical treatment. Microbubbles, due to their small size and ultrasound (US)-enhanced cavitation effects, have attracted considerable clinical attention. They possess the potential for therapeutic application in restricted spaces. We address the above problem with a strategy for the restricted space of root canals. Herein, phase-change nanodroplets (P-NDs) exposed to US are combined with common antibacterial drugs to disrupt a 7 day Enterococcus faecalis biofilm in an in vitro human tooth model. Specifically, the preparation of P-NDs is based on secondary cavitation. Their average particle size is ∼144 nm, and the stability is favorable. The clearance effect for the biofilm is notable (the disruption rate of P-NDs + US is 63.1%, P < 0.01), while the effect of an antibacterial in conjunction with 2% chlorhexidine (Chx) is significant (the antibiofilm rate of P-NDs@2% Chx + US is 96.2%, P < 0.001). Furthermore, biocompatibility testing on human periodontal ligament fibroblasts demonstrated that P-NDs are safe. In summary, the strategy that we have proposed is suitable for the removal of biofilms in root canals. Notably, it also has great potential for application in the treatment of bacterial infections in restricted spaces.

A Novel Antifungal Plasma-Activated Hydrogel.

Antifungal hydrogels with added antifungal drugs have received extensive attention from researchers due to their potential use in various applications, such as wound dressings and ultrasound gel pads. In this study, we proposed and designed an alternative antifungal hydrogel preparation strategy to obtain hydrogels with high antifungal abilities. We employed plasma-activated water (PAW) instead of water in the hydrogel polymerization process to prepare plasma-activated hydrogels (PAHs). Disc diffusion assay results revealed that PAH exhibits satisfactory antifungal activity. Interestingly, the oxidation-reduction potential (ORP) of the PAH was significantly lower than that of conventional polyacrylamide (PAAm) hydrogels, and we provided a possible reaction equation to explain the lower value of ORP in the PAH. Furthermore, using electron spin resonance (ESR) spectroscopy, the hydroxyl radical was detected in PAHs. Although the active ingredients in the hydrogel cannot be quantitatively measured, the hydroxyl radical and NO3- are speculated to be the main components of PAH with antifungal activity according to ESR spectroscopy and optical emission spectroscopy. Further experiments also showed that PAH has a longer antifungal lifetime than PAW. In summary, the proposed plasma-activated hydrogels can provide valuable preparation strategies for delivering antifungal capabilities and have many potential applications in biomedical fields.