Antibacterial and antibiofilm activities of Chinese propolis essential oil microemulsion against Streptococcus mutans.

AIMS: To solve the shortcomings of poor solubility, easy volatilization, and decomposition, propolis essential oil microemulsion (PEOME) was prepared. The antibacterial, antibiofilm activities, and action mechanism of PEOME against Streptococcus mutans was analyzed. METHODS: PEOME was prepared using anhydrous ethanol and Tween-80 as the cosurfactant and surfactant, respectively. The antibacterial activity of PEOME against S. mutans was evaluated using the agar disk diffusion method and broth microdilution method. The effects of PEOME on S. mutans biofilm was detected through the assays of crystal violet (CV), XTT reduction, lactic dehydrogenase (LDH) and calcium ions leaking, live/dead staining and scanning electron microscopy (SEM). And the antibiofilm mechanism of PEOME was elaborated by the assays of extracellular polysaccharide (EPS) production and glucosyltransferase (GTF) activity. RESULTS: The inhibition zone diameter (DIZ) of PEOME against S. mutans was 31 mm, while the minimal inhibitory concentration (MIC) was 2.5 µL mL-1. CV and XTT assays showed that PEOME could prevent fresh biofilm formation and disrupt preformed biofilm through decreasing the activities and biomass of biofilm. The leaking assays for LDH and calcium ions, as well as the live/dead staining assay, indicated that PEOME was able to damage the integrity of bacterial cell membranes within the biofilm. SEM revealed that PEOME had a noticeable inhibitory effect on bacterial adhesion and aggregation through observing the overall structure of biofilm. The assays of EPS production and GTF activity suggested that PEOME could reduce EPS production by inhibiting the activity of GTFs, thus showing an antibiofilm effect. CONCLUSIONS: The significant antibacterial and antibiofilm activities against S. mutans of PEOME meant that PEOME has great potential to be developed as a drug to prevent and cure dental caries caused by S. mutans.

Integrated tea polyphenols and polydopamine functionalized graphene anode for improved bioelectricity generation and Cr(VI) reduction in microbial fuel cells.

Microbial fuel cells (MFCs) have the dual advantage of mitigating Cr(Ⅵ) wastewater ecological threats while generating electricity. However, the low electron transfer efficiency and the limited enrichment of active electrogens are barriers to MFCs advancement. This study describes the synthesis of the TP-PDA-RGO@CC negative electrode using tea polyphenol as a reducing agent and polydopamine-doped graphene, significantly enhances the roughness and hydrophilicity of the anode. The charge transfer resistance was reduced by 94%, and the peak MFC power was 1375.80 mW m-2. Under acidic conditions, the Cr(Ⅵ) reduction rate reached 92% within 24 h, with a 52% increase in coulombic efficiency. Biodiversity analysis shows that the TP-PDA-RGO@CC anode could enrich electrogens, thereby boosting the electron generation mechanism at the anode and enhancing the reduction efficiency of Cr(Ⅵ) in the cathode chamber. This work emphasizes high-performance anode materials for efficient pollutant removal, energy conversion, and biomass reuse.

Utilization of composite particles with customizable cross-linked lignin patches for dental cleansing.

Lignin, a natural polyphenol polymer, is a biocompatible, cost-effective and accessible material. To fully utilize the benefits of lignin, it is crucial to transform its complex macromolecules into nanoscale particles in a single solvent. In this research, an assembly-mediated internal cross-linking method in single solvent was proposed to manufacture cross-linked lignin colloidal particles with nanoscale particle size controlled to be around 50 nm. Then, cross-linked lignin composite particles with a unique "patchy" structure for dental cleansing were obtained by rapidly grafting the cross-linked lignin colloidal particles onto the surface of silica microspheres through the bridging effect of silane coupling agent. The resulting composite particles have rivets with adjustable hardness, significantly lower than traditional abrasives like silica in both hardness and modulus. Through the group cleansing behavior of soft interlocking, a breakthrough has been achieved in the high solid content agglomeration friction mode of traditional abrasives, which effectively reduces tooth wear and exhibits an excellent plaque removal effect.

Evaluation of the self-assembled functional PPFS-P-AM composite for treating oilfield sewage.

Oilfield sewage has a complex composition with large amounts of emulsified oils, polymers and surfactants. Efficient coagulants are required to purify such sewage to meet emissions standards. In this study, oxidized FeSO4·7H2O and NaHCO3were condensed by basic titration and polyferric sulfate phosphate (PPFS) was prepared by the addition of NaH2PO4·2H2O to improve its charge and stability. In addition, by adding modified palygorskite and cationic amylum, a functional polyferric sulfate phosphate, palygorskite and cationic amylum copolymer (PPFS-P-AM) composite coagulant was synthesized through self-assembly, and then used to treat oilfield sewage. The characteristic functional groups and crystal forms of the coagulant were characterized by FTIR and XRD. The zeta potential and radius of gyration (Rh) indicate that the introduction of palygorskite and cationic amylum enhance the charge neutralization and bridging adsorption abilities, respectively. The optimal dosage of cationic amylum is 5% in 80 mg·L-1 PPFS-P-AM, which provides turbidity and oil removal rates of 98% and 94%, respectively. Observation by SEM shows that the micro-morphology of PPFS-P-AM flocs has adendritic distribution with a reticular macromolecular structure that provides good sweeping performance during the sedimentation process. Finally, an analysis of its properties and performance reveals the mechanism by which PPFS-P-AM coagulates oilfield sewage. PPFS-P-AM provides better coagulation than the other studied coagulants via the synergistic effects of reinforced charge neutralization, bridging adsorption and sweeping.

[Relationship between DNA repair gene XRCC1 Arg399Gln polymorphism and susceptibility to prostate cancer in the Han population in Jiangsu and Anhui].

OBJECTIVE: To investigate the association of XRCC1 Arg399Gln polymorphism, smoking and drinking with the risk of prostate cancer (PCa) in the population of Han nationality in Jiangsu and Anhui. METHODS: A case-control study including 207 PCa patients and 235 age-matched controls was conducted. The polymorphisms of XRCC1 Arg399Gln sites were analyzed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique using genomic DNA isolated from peripheral blood lymphocytes. We compared the correlations between the susceptibility to PCa and different genotypes, and investigated the effect of smoking and drinking. RESULTS: The heterozygous Arg/Gln genotype was associated with statistically significantly increased risk of PCa (OR = 1.55, 95% CI: 1.01-2.39) compared with those with Arg/Arg wild-type homozygote. An increased susceptibility to PCa was shown to be associated with the 399Gln allele (either the heterozygous Arg/Gln or the homozygous Gin/Gln genotypes, OR = 1.61, 95% CI: 1.07-2.44) , and heavy smokers (smoking index; > or =20) (OR = 1.94, 95% CI: 1.02-3.71) and superficial smokers (taking smoke into the mouth only) (OR = 2.44, 95% CI: 1.02-5.80) with 399Gln allele demonstrated a significantly increased risk in comparison with those carrying wild genotype. CONCLUSION: XRCC1 Arg399Gln polymorphism might contribute to the susceptibility to PCa. The Arg/Gln and Gln/Gln genotypes might increase the risk of PCa and have synergistic effect with smoking.

Titanium dioxide nanoparticles alter cellular morphology via disturbing the microtubule dynamics.

Titanium dioxide (TiO2) nanoparticles (NPs) have been widely used in our daily lives, for example, in the areas of sunscreens, cosmetics, toothpastes, food products, and nanomedical reagents. Recently, increasing concern has been raised about their neurotoxicity, but the mechanisms underlying such toxic effects are still unknown. In this work, we employed a human neuroblastoma cell line (SH-SY5Y) to study the effects of TiO2 NPs on neurological systems. Our results showed that TiO2 NPs did not affect cell viability but induced noticeable morphological changes until 100 µg ml(-1). Immunofluorescence detection showed disorder, disruption, retraction, and decreased intensity of the microtubules after TiO2 NPs treatment. Both α and ß tubule expressions did not change in the TiO2 NP-treated group, but the percentage of soluble tubules was increased. A microtubule dynamic study in living cells indicated that TiO2 NPs caused a lower growth rate and a higher shortening rate of microtubules as well as shortened lifetimes of de novo microtubules. TiO2 NPs did not cause changes in the expression and phosphorylation state of tau proteins, but a tau-TiO2 NP interaction was observed. TiO2 NPs could interact with tubule heterodimers, microtubules and tau proteins, which led to the instability of microtubules, thus contributing to the neurotoxicity of TiO2 NPs.