Penetration of an antimicrobial zinc-sugar alcohol complex into Streptococcus mutans biofilms

Study on the Synergistic Effects of Cu and Sr on Biodegradable Zn Alloys

Bone defect repair and postoperative infections are among the most challenging issues faced by orthopedic surgeons. Thus, the antibacterial agent Cu and the osteogenic promoter Sr have been widely incorporated into biodegradable alloys separately. However, to the best of our knowledge, the synergistic effects of Cu and Sr on zinc alloys have not been investigated. Therefore, we have developed a series of novel Zn-4Cu-xSr (x = 0.05, 0.1, and 0.3 wt %) alloys. Our results showed that the addition of Cu and Sr significantly increased the strength of pure zinc while maintaining a certain level of ductility. Plastic deformation further enhanced the strength and ductility of the alloys. The tensile strength of HR Zn-4Cu-xSr alloys remains between 233.34 ± 1.31 MPa and 235.81 ± 3.0 MPa, with elongation values ranging from 45.7 ± 1.56% to 49.6 ± 6.22%. The HE Zn-4Cu-0.05Sr alloy exhibits a high elongation of 95.05 ± 11.1%. Furthermore, the HE Zn-4Cu-0.1Sr alloy demonstrates the best overall mechanical performance with ultimate tensile strength (σuts), yield strength (σys), and elongation (ε) values of 252.73 ± 0.12 MPa, 181.0 ± 0.79 MPa, and 42.8 ± 1.13%, respectively. The corrosion rate of HE Zn-4Cu-xSr alloys increases with an increase in Sr content. All samples exhibit satisfactory cytocompatibility with the cells displaying a healthy spindle-like morphology. In vitro antibacterial tests show that the HE Zn-4Cu-xSr alloys exhibit significant antibacterial effects against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli), with the antibacterial properties strengthening as the Sr content increases. Therefore, this study demonstrates the tremendous potential application of Zn-4Cu-xSr alloys in biodegradable zinc alloys for bone fracture fixation and repair.

Alteration of oral microbial biofilms by sweeteners

There is a growing interest in using sweeteners for taste improvement in the food and drink industry. Sweeteners were found to regulate the formation or dispersal of structural components of microbial biofilms. Dietary sugars may enhance biofilm formation and facilitate the development of antimicrobial resistance, which has become a major health issue worldwide. In contrast, bulk and non-nutritive sweeteners are also beneficial for managing microbial infections. This review discusses the clinical significance of oral biofilms formed upon the administration of nutritive and non-nutritive sweeteners. The underlying mechanism of action of sweeteners in the regulation of mono- or poly-microbial biofilm formation and destruction is comprehensively discussed. Bulk and non-nutritive sweeteners have also been used in conjunction with antimicrobial substances to reduce microbial biofilm formation. Formulations with bulk and non-nutritive sweeteners have been demonstrated to be particularly efficient in this regard. Finally, future perspectives with respect to advancing our understanding of mechanisms underlying biofilm regulation activities of sweeteners are presented as well. Several alternative strategies for the application of bulk sweeteners and non-nutritive sweeteners have been employed to control the biofilm-forming microbial pathogens. Gaining insight into the underlying mechanisms responsible for enhancing or inhibiting biofilm formation and virulence properties by both mono- and poly-microbial species in the presence of the sweetener is crucial for developing a therapeutic agent to manage microbial infections.

Semi-solid enzymolysis enhanced the protective effects of fruiting body powders and polysaccharides of Herinaceus erinaceus on gastric mucosal injury

This study demonstrated the effects of semi-solid enzymolysis on physicochemical properties of fruiting body powders and polysaccharides from Hericium erinaceus and protective effects on gastric mucosal injury. Semi-solid enzymolysis could reduce the particle size, change the microstructure of fruiting body powders, increase the contents of soluble polysaccharide (26.26-67.04 %) and uronic acid (16.97-31.12 %) and reduce the molecular weight of polysaccharides. The digestibility of fruiting body powder of H. erinaceus after semi-solid enzymolysis was increased by 31.4 %, compared with that of the fruiting body powder of H. erinaceus without enzymolysis. Semi-solid enzymolysis could enhance the protective effects of the fruiting body powders and polysaccharides on ethanol-induced human gastric mucosal epithelial cells (GES-1) cells, increase the production of superoxide dismutase (SOD, 0-37.33 %) and catalase (CAT, 2.47-18.46 %), and inhibit the production of malonaldehyde (MDA, 2.45-19.62 %), myeloperoxidase (MPO, 0-13.54 %), interleukin (IL-6, 4.39-24.62 %) and tumor necrosis factor-α (TNF-α, 5.97-12.25 %). Semi-solid enzymolysis could improve the inhibition rate of the fruiting body powder on gastric ulcer (32.70-46.26 %), inhibit oxidative stress and inflammation, and protect rats with acute gastric mucosal injury against the stimulation of ethanol on gastric mucosa. In conclusion, semi-solid enzymolysis may enhance the protective effects of the fruiting body powders and polysaccharides on gastric mucosal injury.

High-strength biodegradable zinc alloy implants with antibacterial and osteogenic properties for the treatment of MRSA-induced rat osteomyelitis

Implant-related infections caused by drug-resistant bacteria remain a major challenge faced by orthopedic surgeons. Furthermore, ideal prevention and treatment methods are lacking in clinical practice. Here, based on the antibacterial and osteogenic properties of Zn alloys, Ag and Li were selected as alloying elements to prepare biodegradable Zn-Li-Ag ternary alloys. Li and Ag addition improved the mechanical properties of Zn-Li-Ag alloys. The Zn-0.8Li-0.5Ag alloy exhibited the highest ultimate tensile strength (>530 MPa). Zn-Li-Ag alloys showed strong bactericidal effects on methicillin-resistant Staphylococcus aureus (MRSA) in vitro. RNA sequencing revealed two MRSA-killing mechanisms exhibited by the Zn-0.8Li-0.5Ag alloy: cellular metabolism disturbance and induction of reactive oxygen species production. To verify that the therapeutic potential of the Zn-0.8Li-0.5Ag alloy is greater than that of Ti intramedullary nails, X-ray, micro-computed tomography, microbiological, and histological analyses were conducted in a rat femoral model of MRSA-induced osteomyelitis. Treatment with Zn-0.8Li-0.5Ag alloy implants resulted in remarkable infection control and favorable bone retention. The in vivo safety of this ternary alloy was confirmed by evaluating vital organ functions and pathological morphologies. We suggest that, with its good antibacterial and osteogenic properties, Zn-0.8Li-0.5Ag alloy can serve as an orthopedic implant material to prevent and treat orthopedic implant-related infections.

The Influence of Preventive Regimens Containing Different Toothpastes on Caries Risk of High-Risk Patients: A Randomized Clinical Trial

BACKGROUND: The main objective of conservative dentistry is maintaining the health of the dentition and restored teeth free from dental caries. The prevention of dental caries can be achieved by personal prevention programs at home, dental health care professional, and public health application programs. Based on knowledge related to the etiology and pathogenesis of dental caries, this provides a chance for application of effective prevention program for the prevention of dental caries. AIM: This study aimed to evaluate the effect of different preventive regimens using different toothpastes on caries risk using cariogram and decayed, missing, and filled (DMF) scores of high caries risk patients. MATERIALS AND METHODS: The study was conducted on 66 participants with high caries risk. Participants were divided into three groups, 22 participant each. According to the test regimen, where (A1) participants were exposed to a regimen including dual zinc plus arginine-based toothpaste (Colgate total), (A2) participants were exposed to a regimen including zinc-based toothpaste (Crest complete), and (A3) control group was participants that were exposed to a regimen including fluoride-based toothpaste (Signal). The study was carried for 1 year, assessment of cariogram and DMF scores was done in four intervals: T0: baseline, T3: after 3 months, T6: after 6 months, and T12: after 12 months. RESULTS: According to cariogram, there was a statistically significant difference between Groups A1, A2, and A3, where p < 0.001. However, DMF scores of all groups showed no statistically significant difference between the three groups. CONCLUSIONS: Dual zinc plus arginine-based toothpaste is a superior caries preventive regimen in high caries risk patients. CLINICAL SIGNIFICANCE: The benefits of preventive regimen to the practitioner will be providing a non-invasive, and cost-efficient method to prevent dental caries. Benefits to the patient will be an improvement of oral hygiene, prevention of dental caries, and maintain healthy dental supporting structures.

Investigating Structural Property Relationships to Enable Repurposing of Pharmaceuticals as Zinc Ionophores

The importance of zinc in biology has gained greater recognition in recent years due to its essential contributions to the function of many endogenous enzymes. Disruption of zinc homeostasis may be useful in treating pathological conditions, such as Alzheimer's, and for antiviral purposes. Despite the growth of knowledge and increased interest in zinc, little is known about the structure and function of zinc ionophores. In this study we analyse the Cambridge Structural Database and solution complexation studies found in the literature to identify key functional groups which may confer zinc ionophorism. Pharmaceuticals, nutraceuticals and amino acids with these functionalities were selected to enable us to explore the translatability of ionophoric activity from in vitro assays to cellular systems. We find that although certain species may complex to zinc in the solid and solution states, and may carry ions across simple membrane systems, this does not necessarily translate into ionophoric activity. We propose that the CSD can help refine key functionalities but that ionophoric activity must be confirmed in cellular systems.

Xylitol and erythritol inhibit real-time biofilm formation of Streptococcus mutans

Background

Regular consumption of xylitol decreases the number of cariogenic streptococci in dental plaque. In vitro biofilm models to study the mechanism of xylitol action have been set-up, but the obtained results are contradictory. Biofilm growth is a dynamic process with time-specific characteristics that may remain undetected in conventional end-point biofilm tests. In this study we used an impedance spectroscopy instrument, xCELLigence Real Time Cell Analyzer (RTCA), that allows label-free, non-invasive real-time monitoring of biofilm formation, to explore effects of xylitol on biofilm formation by Streptococcus mutans. Based on the obtained information of biofilm dynamics, we assessed the number of viable bacteria, the polysaccharide content, and the expression levels of selected genes involved in glucan-mediated biofilm formation in different biofilm stages. Xylitol inhibition was compared with that of erythritol; another polyol suggested to have a positive impact on oral health.

Results

Our results showed that real-time monitoring provided new information of polyol-induced changes in S. mutans biofilm formation dynamics. The inhibitory effect of polyols was more pronounced in the early stages of biofilm formation but affected also the measured total amount of formed biofilm. Effects seen in the real-time biofilm assay were only partially explained by changes in CFU values and polysaccharide amounts in the biofilms. Both xylitol and erythritol inhibited real-time biofilm formation by all the nine tested S. mutans strains. Sensitivity of the strains to inhibition varied: some were more sensitive to xylitol and some to erythritol. Xylitol also modified the expression levels of gbpB, gtfB, gtfC and gtfD genes that are important in polysaccharide-mediated adherence of S. mutans.

Conclusion

The erythritol- and xylitol- induced inhibition of biofilm formation was only partly explained by decrease in the number of viable S. mutans cells or the amount of polysaccharides in the biofilm matrix, suggesting that in addition to reduced proliferation also the matrix composition and thereby the surface attachment quality of biofilm matrix may be altered by the polyols.

Quaternary Ammonium Salt-Based Cross-Linked Micelles to Combat Biofilm

Due to self-produced extracellular polymeric substances (EPS), biofilms are hard to eradicate by common antimicrobials. Herein, a new quaternary ammonium salt based cross-linked micelle (QAS@CM) was created to combat biofilms. The QAS@CM adsorbed first onto the biofilm surface through multicharged interaction, then penetrated the EPS in the form of nanoparticles and diffused throughout the films. By responding to the biofilm acid/lipase microenvironment, these nanoparticles would further break into quaternary ammonium oligomers and act as the polyvalent inhibitors to effectively destroy the established biofilm and kill the corresponding bacteria within it.