Study of the scavenger and vector roles of microplastics for polyhalocarbazoles under simulated gastric fluid conditions.

Microplastics entering the digestive system of living organisms can serve as a carrier of hydrophobic organic pollutants (HOPs), increasing their exposure levels and the health risks they pose to both humans and animals. The desorption kinetics of six polyhalocarbazoles (PHCZs) from 5 mm and 0.15 mm polypropylene (PP) and polyvinyl chloride (PVC) microplastic particles were assessed using a combined microplastics and food system, representing the gastric system of vertebrates and invertebrates. Results showed that the chemical transfer of PHCZs is biphasic and reversible, with rapid exchange occurring within 2-48 h, followed by a period of slow transfer, which continues for weeks to months. The desorption capacity of PHCZs loaded on 0.15 mm microplastic particles was greater than that of 5 mm particles. The bioavailability percentage of PHCZ congeners for PP (24.2%-65.3%) and PVC (43.5%-57.2%) in the vertebrate fluid system were all lower than those in the invertebrate system (34.2%-70.7% for PP and 56.3%-72.7% for PVC, respectively). These findings indicate that physiological conditions, such as polarity, ingestion fluid, and microplastic affect the desorption of PHCZs from microplastics. In addition, desorption from PP was inhibited by the presence of foodstuff loaded with PHCZs due to competition, while desorption from PVC was not significantly affected by the presence of PHCZs contaminant food. Microplastics could provide a cleaning function in gastric fluid systems containing contaminated foodstuff, especially PP, which was capable of competitive adsorption of PHCZs from food. Few investigations have focused on the adverse effects of microplastic ingestion on human health, particularly in their role as vectors for HOPs, compared to other routes of exposure and transport. Therefore, these findings provide valuable insight into the health risks associated with dietary intake of microplastics and HOPs.

A comparative study on root canal repair materials: a cytocompatibility assessment in L929 and MG63 cells.

Cytocompatibility of repair materials plays a significant role in the success of root canal repair. We conducted a comparative study on the cytocompatibility among iRoot BP Plus, iRoot FS, ProRoot MTA, and Super-EBA in L929 cells and MG63 cells. The results revealed that iRoot FS was able to completely solidify within 1 hour. iRoot BP Plus required 7-day incubation, which was much longer than expected (2 hours), to completely set. ProRoot MTA and Super-EBA exhibited a similar setting duration of 12 hours. All the materials except Super-EBA possessed negligible in vitro cytotoxicity. iRoot FS had the best cell adhesion capacity in both L929 and MG63 cells. With rapid setting, negligible cytotoxicity, and enhanced cell adhesion capacity, iRoot FS demonstrated great potential in clinical applications. Future work should focus on longer-term in vitro cytocompatibility and an in vivo assessment.

Coaxial Electrospun Polycaprolactone/Gelatin Nanofiber Membrane Loaded with Salidroside and Cryptotanshinone Synergistically Promotes Vascularization and Osteogenesis.

Background: Salidroside (SAL) is the most effective component of Rhodiola rosea, a traditional Chinese medicine. Cryptotanshinone (CT) is the main fat-soluble extract of Salvia miltiorrhiza, exhibiting considerable potential for application in osteogenesis. Herein, a polycaprolactone/gelatin nanofiber membrane loaded with CT and SAL (PSGC membrane) was successfully fabricated via coaxial electrospinning and characterized. Methods and Results: This membrane capable of sustained and controlled drug release was employed in this study. Co-culturing the membrane with bone marrow mesenchymal stem cells and human umbilical vein endothelial cells revealed excellent biocompatibility and demonstrated osteogenic and angiogenic capabilities. Furthermore, drug release from the PSGC membrane activated the Wnt/ß-catenin signaling pathway and promoted osteogenic differentiation and vascularization. Evaluation of the membrane's vascularization and osteogenic capacities involved transplantation onto a rat's subcutaneous area and assessing rat cranium defects for bone regeneration, respectively. Microcomputed tomography, histological tests, immunohistochemistry, and immunofluorescence staining confirmed the membrane's outstanding angiogenic capacity two weeks post-operation, with a higher incidence of osteogenesis observed in rat cranial defects eight weeks post-surgery. Conclusion: Overall, the SAL- and CT-loaded coaxial electrospun nanofiber membrane synergistically enhances bone repair and regeneration.

Activity enhancement and the anammox mechanism under low temperature via PVA-SA and nano Fe2O3-PVA-SA entrapped beads.

Anaerobic ammonia-oxidizing bacteria (AAOB) have a long growth time and low activity at low temperatures. In suspended systems, sludge is easily lost, which limits the mainstream application of anaerobic ammonia oxidation (anammox).Entrapment provides effective ideas for solving these problems. In this study, polyvinyl­sodium alginate (PVA-SA) and nano Fe2O3-PVA-SA entrapment beads were prepared to discuss the effectiveness of entrapment enhanced anammox sludge at low temperatures. The differences in the entrapped beads and granules were compared to analyze the strengthening mechanism. The results show that the nitrogen removal performance of granules, PVA-SA and nano Fe2O3-PVA-SA entrapped beads, first decreased and then increased during the cooling and low-temperature operation. Nano Fe2O3-PVA-SA entrapped beads showed the smallest decline and the highest degree of recovery. Reaction metering ratio (△NO2--N/△NH4+-N and △NO3--N/△NH4+-N) showed that entrapment could realize Nitrite oxidizing bacteria (NOB) inhibition and improve the activity of denitrifying bacteria (DNB) to promote the removal of total nitrogen by providing a strict anaerobic environment. The results demonstrate that entrapment is beneficial for maintaining the content of heme c, specifically, nano Fe2O3 can stimulate its production, and is beneficial for alleviating the reduction of hydrazine dehydrogenase (HDH) enzyme activity. The extracellular polymeric substances (EPS) content and analysis showed that entrapment does not change the composition of EPS, and can maintain the EPS content. Nano Fe2O3 can stimulate AAOB to secrete more EPS to maintain sludge stability. From a molecular perspective, entrapment can maintain the expression of functional genes, promote the enrichment of AAOB, thus improving the nitrogen removal performance from the dual perspectives of "quality" and "quantity".

A high-strength biodegradable thermoset polymer for internal fixation bone screws: Preparation, in vitro and in vivo evaluation.

Thermoset polymers synthesized from the polycondensation of glycerol with biocompatible diacids represent a promising class of absorbable materials for biomedical applications. However, the utility of these polymers for bone fixation devices is hampered due to the lack of mechanical strength. Herein we synthesized a high-strength thermoset polymer, poly(glycerol-succinate) (PGS), via a catalyst-free and solvent-free reaction. The bending strength of PGS reaches 122.01 ±â€¯8.82 MPa, signifying its great potential for fixation devices. The degradation property of the polymer can be tuned by adjusting the monomer ratio and reaction time. Bone screws based on the PGS polymer were successfully manufactured using a lathe. In vitro evaluation showed the PGS polymer was able to well support cell adhesion and proliferation. In vivo evaluation using a rat subcutaneous implantation model showed that the inflammatory response to the polymer was mild. After the PGS screws were implanted in the rabbit femoral condyle for 12 weeks, micro-computed tomography (micro-CT) and histological analysis revealed that the screws achieved good osseointegration. Consequently, the polymer developed in current study can serve as internal fixation devices due to the proper mechanical strength, excellent biocompatibility, and feasibility of manufacturing screws.

[The antibacterial efficacy of KaVo KEY laser on Enterococcus faecalis within infected root canals and roots surface in vitro].

OBJECTIVE: To evaluate the antibacterial efficacy of KaVo KEY laser on Enterococcus faecalis (E. faecalis) within infected root canals and roots surface in vitro. METHODS: Fifty single-rooted teeth were selected, and infected root canals and roots surface vitro models were prepared. Then, these specimens were divided into three groups. First group were untreated as blank control. The other two groups were the laser groups: Irradiated 15 s and 30 s respectively with 80 mJ and 140 mJ in root canals and on roots surface. Microbiological samples were collected from root canals and roots surface at two time points (before irrigation and immediately after irrigation). The dentin chips from three different zone of part of root canals in each group were immediately collected and were cultured for 24 h in brain heart infusion (BHI). RESULTS: The number of E. faecalis in root canal and root surface in each of the groups were effectively reduced (P < 0.05), and there was no significant difference between each two groups (P > 0.05). Compared with the blank control, the bacterial number in 100 microm of dental tubules decreased after specimens treated with 80 mJ, and the experimental group irradiated 15 s was a significant decease (P < 0.05). The other groups were no changed in different zone of dental tubules. CONCLUSION: KaVo KEY laser is effective on sterilizing infected root canals and roots surface. It has also significant effect on bacterial in superficial dental tubules with low energy and short time.