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Background Achieving rapid and secure hemostasis of the vascular access point is important for patients undergoing maintenance hemodialysis (HD). We developed a polyacrylic acid-polyvinylpyrrolidone (PAA-PVP) complex that absorbs moisture such as blood or sterilizing solution, forms a hydrogel, and adheres to the body’s surface, thereby exerting a powerful hemostatic effect. This study aims to compare the effect of PAA-PVP complex versus a conventional non-woven fabric pad on hemostasis at the needle puncture vascular access site in patients on HD. Methods This open-label crossover randomized controlled trial will include 50 participants who undergo thrice-weekly HD. Participants in whom hemostasis requires more than 10 min by compression using a conventional pad or who have a severe skin problem at the needle puncture vascular access site will be excluded from the study. Participants will be randomized in a 1:1 ratio to receive either the PAA-PVP complex or conventional pads. Three consecutive weekly hemostatic tests will be performed at 11, 9, 7, 5, 3, and 1 min. The study will employ an individual 3+3 design in which participants in whom hemostasis is achieved in all three sessions in a week will be challenged to a shorter time in the three sessions of the next week. Those in whom hemostasis is achieved in two of three sessions will be tested at the same time point in the three sessions of the next week. The study treatment will be terminated if hemostasis is achieved in only one or none of the sessions, and the minimum time with three consecutive successes will be recorded as the hemostasis time. The primary endpoint, the hemostasis time on the arterial side of the vascular access, will be analyzed using mixed-effect models for repeated measures and include the hemostatic technique and group, period, and individual effects as covariates. Discussion The study will provide evidence on whether the PAA-PVP complex reduces hemostasis time of the vascular access compared to conventional pad in patients on HD. Trial registration jRCTs032220597 (Japan Registry of Clinical Trials; registered on January 30, 2023, https://jrct.niph.go.jp/latest-detail/jRCTs032220597 ).

To investigate how substrate properties influence stem-cell fate, we cultured single human epidermal stem cells on polydimethylsiloxane (PDMS) and polyacrylamide (PAAm) hydrogel surfaces, 0.1 kPa–2.3 MPa in stiffness, with a covalently attached collagen coating. Cell spreading and differentiation were unaffected by polydimethylsiloxane stiffness. However, cells on polyacrylamide of low elastic modulus (0.5 kPa) could not form stable focal adhesions and differentiated as a result of decreased activation of the extracellular-signal-related kinase (ERK)/mitogen-activated protein kinase (MAPK) signalling pathway. The differentiation of human mesenchymal stem cells was also unaffected by PDMS stiffness but regulated by the elastic modulus of PAAm. Dextran penetration measurements indicated that polyacrylamide substrates of low elastic modulus were more porous than stiff substrates, suggesting that the collagen anchoring points would be further apart. We then changed collagen crosslink concentration and used hydrogel–nanoparticle substrates to vary anchoring distance at constant substrate stiffness. Lower collagen anchoring density resulted in increased differentiation. We conclude that stem cells exert a mechanical force on collagen fibres and gauge the feedback to make cell-fate decisions. The spreading and differentiation of stem cells is influenced by the mechanical properties—in particular by the stiffness—of the extracellular matrix. Now, experiments on epidermal stem cells cultured on substrates with a covalently attached collagen coating show that stem cells sense the stiffness of the substrate through the anchoring density of collagen fibres.

To evaluate the effect of antiseptic soap on single and dual-species biofilms of Candida albicans and Streptococcus mutans on denture base and reline resins. Samples of the resins were distributed into groups (n = 9) according to the prevention or disinfection protocols. In the prevention protocol, samples were immersed in the solutions (Lifebuoy, 0.5% sodium hypochlorite solution and PBS) for 7, 14 and 28 days before the single and dual-species biofilms formation. Overnight denture disinfection was simulated. In the disinfection protocol, samples were immersed in the same solutions during 8 hours after the single and dual-species biofilms formation. Antimicrobial activity was analyzed by counting colony-forming units (CFU/mL) and evaluating cell metabolism. Cell viability and protein components of the biofilm matrix were evaluated using confocal laser scanning microscopy (CLSM). Data were submitted to ANOVA, followed by Tukey’s post-test (α = 0.05) or Dunnett’s T3 multiple comparisons test. In the prevention protocol, Lifebuoy solution effectively reduced the number of CFU/mL of both species. In addition, the solution decreased the cell metabolism of the microorganisms. Regarding disinfection protocol, the Lifebuoy solution was able of reduce approximately of 2–3 logs for all the biofilms on the denture base and reline resin. Cellular metabolism was also reduced. The images obtained with CLSM corroborate these results. Lifebuoy solution was effective in reducing single and dual-species biofilms on denture base and reline resins.

This study aims to investigate the bacterial adhesion effect of heat-curing acrylic resins modified with zirconia nanoparticles when interacting with vegan beverages using SEM and FTIR analyses. The bacterial adhesion of heat-cured acrylic resins from Imicryl and Procryla was investigated. The focus was on modified versions of Procryla containing 1 wt% and 3 wt% zirconia nanoparticles. A total of 192 specimens ( n  = 48 per group) were soaked in four different solutions: distilled water, mineral water, almond milk, and water kefir. Repeated measures ANOVA revealed statistically significant differences ( P  < .05) in bacterial adhesion among resin groups, beverage types, and immersion times. Specifically, the addition of 1% by weight zirconia to the specimens reduced bacterial adhesion in groups immersed in distilled water ( P  < .001). Similarly, 3 wt% zirconia reduced adhesion in mineral water ( P  < .001). However, in groups exposed to other beverages, including mineral water, almond milk, and water kefir, the incorporation of either 1 wt% or 3 wt% zirconia increased bacterial adhesion significantly ( P  < .001). SEM images corroborated these findings, showing varying patterns of bacterial adhesion on the surfaces of different resin groups under different environmental conditions. The findings indicate the importance of resin composition and beverage type in dictating bacterial interactions on acrylic surfaces. Notably, the addition of zirconia nanoparticles, particularly in Procryla 1Z, demonstrated a significant reduction in bacterial adhesion, highlighting its potential to enhance the antimicrobial properties of acrylic materials. Key points • Zirconia reduces bacterial adhesion in water. • Higher zirconia increases adhesion in vegan beverages. Graphical Abstract

Understanding the spatiotemporal effects of surface topographies and modulated stiffness and anisotropic stresses of hydrogels on cell growth remains a biophysical challenge. Here we introduce the photolithographic patterning or two-photon laser scanning confocal microscopy patterning of a series of o-nitrobenzylphosphate ester nucleic acid-based polyacrylamide hydrogel films generating periodically-spaced circular patterned domains surrounded by continuous hydrogel matrices. The patterning processes lead to guided modulated stiffness differences between the patterned domains and the surrounding hydrogel matrices, and to the selective functionalization of sub-regions of the films with nucleic acid anchoring tethers. HeLa cells are deposited on the circularly-shaped domains functionalized with the MUC-1 aptamers. Initiation of the hybridization chain reaction by nucleic acid tethers associated with the continuous hydrogel matrix results in stress-induced ordered orthogonal shape-changes on the patterned domains, leading to ordered shapes of cell aggregates bound to the patterns. Spatiotemporal patterning of hydrogel matrices has been used to control cell behavior. Here the authors present photoresponsive DNA-based hydrogels and demonstrate patterning of physical and biochemical properties to tune local cell responses.

This research aimed to create bifunctional acrylic waterborne coatings capable of absorbing UV radiation and resisting microbial growth. The compound 4-[2(3-acetylphenyl) diazenyl]-3,5-dimethylphenol (ADD) was incorporated into the waterborne acrylic resin at concentrations of 0.1%, 0.25%, and 0.5%. The coatings underwent characterization through scanning electron microscopy (SEM), mechanical property testing, and the CIELab color method after 500 h of UV exposure to assess their UV shielding effectiveness. Furthermore, the antimicrobial properties of both ADD powder and the coatings were evaluated against Gram-negative bacteria ( Helicobacter pylori ), Gram-positive bacteria ( Staphylococcus aureus ), and pathogenic fungi ( Candida albicans ) using the disc diffusion method. Results indicated that the coatings with 0.25% and 0.5% ADD retained their integrity, showing no cracks or color and texture changes after UV exposure. In contrast, the 0.1% ADD coating exhibited significant alterations in the a* value, revealing its susceptibility to UV damage and limited UV absorption. Positive a* values confirmed the red tint of the films. Antimicrobial activity was notable, with inhibition zones measuring 14 to 26 mm against Staphylococcus aureus , 11 to 21 mm against Helicobacter pylori , and 12 to 20 mm against Candida albicans . Overall, this study demonstrated that the developed coatings with ADD significantly enhance UV absorption and exhibit promising antimicrobial properties, effectively overcoming the limitations of existing commercial coatings and offering a viable solution for protecting surfaces from UV radiation and microbial contamination.

Background Three-dimensional (3D) printing technology has revolutionized dentistry, particularly in fabricating provisional restorations. This systematic review and meta-analysis aimed to thoroughly evaluate the flexural strength of provisional restorations produced using 3D printing while considering the impact of different resin materials. Methods A systematic search was conducted across major databases (ScienceDirect, PubMed, Web of Sciences, Google Scholar, and Scopus) to identify relevant studies published to date. The inclusion criteria included studies evaluating the flexural strength of 3D-printed provisional restorations using different resins. Data extraction and quality assessment were performed using the CONSORT scale, and a meta-analysis was conducted using RevMan 5.4 to pool results. Results Of the 1914 initially identified research articles, only 13, published between January 2016 and November 2023, were included after screening. Notably, Digital Light Processing (DLP) has emerged as the predominant 3D printing technique, while stereolithography (SLA), Fused Deposition Modeling (FDM), and mono-liquid crystal displays (LCD) have also been recognized. Various printed resins have been utilized in different techniques, including acrylic, composite resins, and methacrylate oligomer-based materials. Regarding flexural strength, polymerization played a pivotal role for resins used in 3D or conventional/milled resins, revealing significant variations in the study. For instance, SLA-3D and DLP Acrylate photopolymers displayed distinct strengths, along with DLP bisacrylic, milled PMMA, and conventional PMMA. The subsequent meta-analysis indicated a significant difference in flexure strength, with a pooled Mean Difference (MD) of − 1.25 (95% CI − 16.98 - 14.47; P  < 0.00001) and a high I 2 value of 99%, highlighting substantial heterogeneity among the studies. Conclusions This study provides a comprehensive overview of the flexural strength of 3D-printed provisional restorations fabricated using different resins. However, further research is recommended to explore additional factors influencing flexural strength and refine the recommendations for enhancing the performance of 3D-printed provisional restorations in clinical applications.

Electronic skins have received increasing attention in biomedical areas. Current efforts about electronic skins are focused on the development of multifunctional materials to improve their performance. Here, the authors propose a novel natural‐synthetic polymers composite structural color hydrogel film with high stretchability, flexibility, conductivity, and superior self‐reporting ability to construct ideal multiple‐signal bionic electronic skins. The composite hydrogel film is prepared by using the mixture of polyacrylamide (PAM), silk fibroin (SF), poly(3,4‐ethylenedioxythiophene):poly (4‐styrene sulfonate) (PEDOT:PSS, PP), and graphene oxide (GO) to replicate colloidal crystal templates and construct inverse opal scaffolds, followed by subsequent acid treatment. Due to these specific structures and components, the resultant film is imparted with vivid structural color and high conductivity while retaining the composite hydrogel's original stretchability and flexibility. The authors demonstrate that the composite hydrogel film has obvious color variation and electromechanical properties during the stretching and bending process, which could thus be utilized as a multi‐signal response electronic skin to realize real‐time color sensing and electrical response during human motions. These features indicate that the proposed composite structural color hydrogel film can widen the practical value of bionic electronic skins. A stretchable and conductive composite structural color hydrogel film with superior self‐reporting ability can be utilized as an intelligent multiple‐signal bionic electronic skin. The composite hydrogel film exhibits obvious color and electrical variation during the stretching and bending process, which makes it feasible to realize real‐time color sensing and electrical response during human motions.

Dental resin composites have been widely used in a variety of direct and indirect dental restorations due to their aesthetic properties compared to amalgams and similar metals. Despite the fact that dental resin composites can contribute similar mechanical properties, they are more likely to have microbial accumulations leading to secondary caries. Therefore, the effective and long-lasting antimicrobial properties of dental resin composites are of great significance to their clinical applications. The approaches of ascribing antimicrobial properties to the resin composites may be divided into two types: The filler-type and the resin-type. In this review, the resin-type approaches were highlighted. Focusing on the antimicrobial polymers used in dental resin composites, their chemical structures, mechanical properties, antimicrobial effectiveness, releasing profile, and biocompatibility were included, and challenges, as well as future perspectives, were also discussed.

From flocking birds to swarming insects, interactions of organisms large and small lead to the emergence of collective dynamics. Here, we report striking collective swimming of bovine sperm in dynamic clusters, enabled by the viscoelasticity of the fluid. Sperm oriented in the same direction within each cluster, and cluster size and cell-cell alignment strength increased with viscoelasticity of the fluid. In contrast, sperm swam randomly and individually in Newtonian (nonelastic) fluids of low and high viscosity. Analysis of the fluid motion surrounding individual swimming sperm indicated that sperm-fluid interaction was facilitated by the elastic component of the fluid. In humans, as well as cattle, sperm are naturally deposited at the entrance to the cervix and must swim through viscoelastic cervical mucus and other mucoid secretions to reach the site of fertilization. Collective swimming induced by elasticity may thus facilitate sperm migration and contribute to successful fertilization. We note that almost all biological fluids (e.g. mucus and blood) are viscoelastic in nature, and this finding highlights the importance of fluid elasticity in biological function.