Anti-Bacteria and Microecosystem-Regulating Effects of Dental Implant Coated with Dimethylaminododecyl Methacrylate.

The effects of dimethylaminododecyl methacrylate (DMADDM) modified titanium implants on bacterial activity and microbial ecosystem of saliva-derived biofilm were investigated for the first time. Titanium discs were coated with DMADDM solutions at mass fractions of 0 mg/mL (control), 1, 5 and 10 mg/mL, respectively. Biomass accumulation and metabolic activity of biofilms were tested using crystal violet assay and MTT (3-(4,5-Dimethyl-thiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. 16S rRNA gene sequencing was performed to measure the microbial community. Live/dead staining and scanning electron microscopy (SEM) were used to value the structure of biofilm. The results showed that the higher mass fraction of DMADDM the coating solution had, the significantly lower the values of metabolic activity and accumulated biofilms got, as well as fewer live cells and less extracellular matrix. Moreover, 5 mg/mL of DMADDM was the most effective concentration, as well as 10 mg/mL. In microecosystem-regulation, the DMADDM modified titanium implant decreased the relative abundance of Neisseria and Actinomyces and increased the relative abundance of Lactobacillus, a probiotic for peri-implant diseases. In conclusion, via inhibiting growth and regulating microecosystem of biofilm, this novel titanium implant coating with DMADDM was promising in preventing peri-implant disease in an 'ecological manner'.

Antibacterial effect of dental adhesive containing dimethylaminododecyl methacrylate on the development of Streptococcus mutans biofilm.

Antibacterial bonding agents and composites containing dimethylaminododecyl methacrylate (DMADDM) have been recently developed. The objectives of this study were to investigate the antibacterial effect of novel adhesives containing different mass fractions of DMADDM on Streptococcus mutans (S. mutans) biofilm at different developmental stages. Different mass fractions of DMADDM were incorporated into adhesives and S. mutans biofilm at different developmetal stages were analyzed by MTT assays, lactic acid measurement, confocal laser scanning microscopy and scanning electron microscopy observations. Exopolysaccharides (EPS) staining was used to analyze the inhibitory effect of DMADDM on the biofilm extracellular matrix. Dentin microtensile strengths were also measured. Cured adhesives containing DMADDM could greatly reduce metabolic activity and lactic acid production during the development of S. mutans biofilms (p < 0.05). In earlier stages of biofilm development, there were no significant differences of inhibitory effects between the 2.5% DMADDM and 5% DMADDM group. However, after 72 h, the anti-biofilm effects of adhesives containing 5% DMADDM were significantly stronger than any other group. Incorporation of DMADDM into adhesive did not adversely affect dentin bond strength. In conclusion, adhesives containing DMADDM inhibited the growth, lactic acid production and EPS metabolism of S. mutans biofilm at different stages, with no adverse effect on its dentin adhesive bond strength. The bonding agents have the potential to control dental biofilms and combat tooth decay, and DMADDM is promising for use in a wide range of dental adhesive systems and restoratives.

Novel flexible magnetoelastic biosensor based on PDMS/FeSiB/QD composite film for the detection of African swine fever virus P72 protein.

African swine fever (ASF) is a highly contagious and severe hemorrhagic disease caused by the African swine fever virus (ASFV). The continuous spread of ASFV affects the safety of the global meat supply; therefore, the establishment of sensitive and specific detection methods for ASFV has become an important hot spot in food safety. Herein, we developed a flexible magnetoelastic (ME) biosensor based on PDMS/FeSiB/QDs composite films for the detection of ASFV P72 protein. Based on the high luminescence performance of CsPbBr3 quantum dots and the excellent magnetoelastic effect of FeSiB, flexible ME biosensors convert stress signals generated by antibody-antigen-specific binding into optical and electromagnetic signals. The nanostructures covalently linked by quantum dots and PDMS provide biomodification sites for ASFV P72 antibodies, simplifying the functionalization modification process compared to the case of conventional biosensors. The deformation of the PDMS film is amplified, and the conversion of surface stress signals to electrical signals is enhanced by exposing the biosensor to a uniform magnetic field. The experimental results proved that the flexible ME biosensor has a wide linear range of 10 ng mL-1-100 µg mL-1, and the detection limit is as low as 0.079 ng mL-1. Moreover, the flexible ME biosensor also shows good stability, sensitivity and specificity, confirming the potential for early disease screening.

External Electrons Directly Stimulate Escherichia coli for Enhancing Biological Hydrogen Production.

External electric field has the potential to influence metabolic processes such as biological hydrogen production in microorganisms. Based on this concept, we designed and constructed an electroactive hybrid system for microbial biohydrogen production under an electric field comprised of polydopamine (PDA)-modified Escherichia coli (E. coli) and Ni foam (NF). In this system, electrons generated from NF directly migrate into E. coli cells to promote highly efficient biocatalytic hydrogen production. Compared to that generated in the absence of electric field stimulation, biohydrogen production by the PDA-modified E. coli-based system is significantly enhanced. This investigation has demonstrated the mechanism for electron transfer in a biohybrid system and gives insight into precise basis for the enhancement of hydrogen production by using the multifield coupling technology.

Magneto-Mechanical Coupling Study of Magnetorheological Elastomer Thin Films for Sensitivity Enhancement.

Magnetorheological elastomer thin films (MREFs) exhibit remarkable deformability and an adjustable modulus under magnetic fields, rendering them promising in fields such as robotics, flexible sensors, and biomedical engineering. Here, we fabricated MREF by introducing magnetostrictive particles (MSPs) and evaluated the magneto-mechanical coupling effect on the enhancement of sensitivity. The saturation magnetization (Ms) in a parallel anisotropic TbDyFe-PDMS MREF was 5.8 emu/g, and the initial tensile modulus was 55% greater than that of an Iso MREF. We propose a nonlinear magnetorheological formula on the magnetostriction effect, incorporating magnetic dipole interactions and the nonlinear prestress of magnetic particles. This formula highlights the complex nonlinear relationship between the external magnetic field (H) and the key parameters that affect the enhanced MR effect of MSPs-MREF, such as saturation magnetization, remanence (Mr), magnetostriction constant (λs) and stress deviator in ferromagnetic particles (Sed) in the magnetic chain structure. Furthermore, we validate the influence of the key parameters of the rectified magnetorheological formula on a nonlinear magneto-mechanical behavior of MSPs-MREF in PDMS-based MSPs-MREF models by using finite-element simulations. Finally, we developed a biosensor based on MSPs-MREF to detect human serum albumin at low concentrations in human urine samples. There is a 4-fold increase in sensitivity, a lower detection of limit (0.442 µg/mL), and a faster response time (15 min) than traditional biosensors, which in the future might provide an effective way of detecting biomolecules of low concentrations.

Nanoparticles of Cerium-Doped Zeolitic Imidazolate Framework-8 Promote Soft Tissue Integration by Reprogramming the Metabolic Pathways of Macrophages.

Soft tissue integration around the abutment of implants is the basis of long-term retention of implants. Macrophages are an important component involved in the repair of soft tissue due to their crucial role in improving the biological structure of connective tissues by regulating the fiber synthesis, adhesion, and contraction of gingival fibroblasts. Recent studies have illustrated that cerium-doped zeolitic imidazolate framework-8 (Ce@ZIF-8) nanoparticles (NPs) can attenuate periodontitis via both antibacterial and anti-inflammatory effects. However, the effect of Ce@ZIF-8 NPs on soft tissue integration around the abutment is unknown. Herein, we first prepared Ce@ZIF-8 NPs by a one-pot synthesis. Then, we probed the regulatory effect of Ce@ZIF-8 NPs on macrophage polarization, and further experiments were performed to study the changes of fiber synthesis as well as adhesion and contraction of fibroblasts in the M2 macrophage environment stimulated by Ce@ZIF-8 NPs. Strikingly, Ce@ZIF-8 NPs can be internalized by M1 macrophages through macropinocytosis and caveolae-mediated endocytosis in addition to phagocytosis. By catalyzing hydrogen peroxide to produce oxygen, the mitochondrial function was remedied, while hypoxia inducible factor-1α was restrained. Then, macrophages were shifted from the M1 to M2 phenotype via this metabolic reprogramming pathway, provoking soft tissue integration. These results provide innovative insights into facilitating soft tissue integration around implants.

Novel dental implant modifications with two-staged double benefits for preventing infection and promoting osseointegration in vivo and in vitro.

Peri-implantitis are a major problem causing implant failure these days. Accordingly, anti-infection during the early stage and subsequent promotion of osseointegration are two main key factors to solve this issue. Micro-arc oxidation (MAO) treatment is a way to form an oxidation film on the surface of metallic materials. The method shows good osteogenic properties but weak antibacterial effect. Therefore, we developed combined strategies to combat severe peri-implantitis, which included the use of a novel compound, PD, comprising dendrimers poly(amidoamine) (PAMAM) loading dimethylaminododecyl methacrylate (DMADDM) as well as MAO treatment. Here, we explored the chemical properties of the novel compound PD, and proved that this compound was successfully synthesized, with the loading efficiency and encapsulation efficiency of 23.91% and 31.42%, respectively. We further report the two-stage double benefits capability of PD + MAO: (1) in the first stage, PD + MAO could decrease the adherence and development of biofilms by releasing DMADDM in the highly infected first stage after implant surgery both in vitro and in vivo; (2) in the second stage, PD + MAO indicated mighty anti-infection and osteoconductive characteristics in a rat model of peri-implantitis in vivo. This study first reports the two-staged, double benefits of PD + MAO, and demonstrates its potential in clinical applications for inhibiting peri-implantitis, especially in patients with severe infection risk.

Dopamine self-polymerized along with hydroxyapatite onto the preactivated titanium percutaneous implants surface to promote human gingival fibroblast behavior and antimicrobial activity for biological sealing.

The clinical success of dental implants requires not only the optimum osseointegration but also the integration of implant surface with soft tissues to form biological sealing. In this study, alkali-heat treatment was applied to modify the pure titanium surface constructing a unique micro-and nano-structure. Then, poly(dopamine), along and with the additional incorporation of hydroxyapatite and carboxymethyl chitosan have been successfully infiltrated into the preactivated Ti surface during dopamine self-polymerization proceeding. Here, the effects of poly(dopamine)-modified surface coating on the biological behaviors of human gingival fibroblasts (HGFs) and oral pathogens have been systematically studied, which was critical for the early peri-implant soft tissue integration. The results showed that the poly(dopamine)-modified alkali-heat-titanium surface was a superior substrate for human gingival fibroblast adhesion, spread and proliferation. Moreover, further enhancements on cytoskeleton organization, collagen secretion and fibronectin adsorption were generally observed through the additional incorporation of hydroxyapatite. The addition of carboxymethyl chitosan exerted a positive modulation effect on antibacterial activity. Overall, our study demonstrated that combined superior soft tissue integration and antibacterial activity can be achieved by using poly(dopamine)-modified titanium implant, which has great potential in the optimal design of dental implant.

Novel Dental Adhesive with Biofilm-Regulating and Remineralization Capabilities.

The mechanical properties and anti-caries effect of a novel anti-caries adhesive containing poly (amidoamine) dendrimer (PAMAM) and dimethylaminododecyl methacrylate (DMADDM) were investigated for the first time. Microtensile bond strength and surface charge density were measured for the novel anti-caries adhesives. Streptococcus mutans, Streptococcus sanguinis, and Streptococcus gordonii were chosen to form three-species biofilms. Lactic acid assay, MTT (3-(4,5-Dimethyl-thiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, exopolysaccharide staining and live/dead staining were performed to study anti-biofilm effect of the adhesive. The TaqMan realtime polymerase chain reaction was used to study the proportion change in three-species biofilms of different groups. The Scanning Electron Microscope (SEM) was used to observe the remineralization effect of PAMAM and DMADDM. The results showed that incorporating PAMAM and DMADDM into adhesive had no adverse effect on the dentin bond strength. The 1% PAMAM and 5% DMADDM adhesive group showed anti-biofilm properties and developed a healthier biofilm with a lower chance of inducing dental caries. Combination of 1% PAMAM and 5% DMADDM solution maintained remineralization capability on dentin, similar to that using 1% PAMAM alone. In conclusion, the adhesive containing PAMAM and DMADDM had strong antimicrobial properties and biological remineralization capabilities, and is promising for anti-caries clinical applications.

Anti-Caries Effects of Dental Adhesives Containing Quaternary Ammonium Methacrylates with Different Chain Lengths.

The objectives of this study were to investigate the effects of dental adhesives containing quaternary ammonium methacrylates (QAMs) with different alkyl chain lengths (CL) on ecological caries prevention in vitro. Five QAMs were synthesized with a CL = 3, 6, 9, 12, and 16 and incorporated into adhesives. Micro-tensile bond strength and surface charge density were used to measure the physical properties of the adhesives. The proportion change in three-species biofilms consisting of Streptococcus mutans, Streptococcus sanguinis, and Streptococcus gordonii was tested using the TaqMan real-time polymerase chain reaction. Lactic acid assay, MTT [3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay, exopolysaccharide staining, live/dead staining, scanning electron microscopy (SEM), and transverse microradiography (TMR) were performed to study the anti-biofilm and anti-demineralization effects of the dental adhesives. The results showed that incorporating QAMs with different alkyl chain lengths into the adhesives had no obvious effect on the dentin bond strength. The adhesives containing QAMs with a longer alkyl chain developed healthier biofilms. The surface charge density, anti-biofilm, and anti-demineralization effects of the adhesives increased with a CL of the QAMs from 3 to 12, but decreased slightly with a CL from 12 to 16. In conclusion, adhesives containing QAMs with a tailored chain length are promising for preventing secondary caries in an "ecological way".

Effect of anti-biofilm glass-ionomer cement on Streptococcus mutans biofilms.

Dental restorative materials with antimicrobial properties can inhibit bacterial colonization, which may result in a reduction of caries at tooth-filling interaction zones. This study aimed to develop antibacterial glass-ionomer cements (GIC) containing a quaternary ammonium monomer (dimethylaminododecyl methacrylate, DMADDM), and to investigate their effect on material performance and antibacterial properties. Different mass fractions (0, 1.1% and 2.2%) of DMADDM were incorporated into the GIC. The flexure strength, surface charge density, surface roughness and fluoride release were tested. A Streptococcus mutans biofilm model was used. Exopolysaccharides (EPS) staining was used to analyze the inhibitory effect of DMADDM on the biofilm matrix. In addition, biofilm metabolic activity, lactic acid metabolism and the expression of glucosyltransferase genes gtfB, gtfC and gtfD were measured. GIC containing 1.1% and 2.2% DMADDM had flexural strengths matching those of the commercial control (P>0.1). DMADDM was able to increase the surface charge density but reduced surface roughness (P<0.05). The incorporation of 1.1% and 2.2% DMADDM elevated the release of fluoride by the GIC in the first 2 days (P<0.05). The novel DMADDM-modified GIC significantly reduced biofilm metabolic activity (P<0.05) and decreased lactic acid production (P<0.05). The quantitative polymerase chain reaction (qPCR) results showed that the expression of gtfB, gtfC and gtfD decreased when mass fractions of DMADDM increased (P<0.05). EPS staining showed that both the bacteria and EPS in biofilm decreased in the DMADDM groups. The incorporation of DMADDM could modify the properties of GIC to influence the development of S. mutans biofilms. In this study, we investigated the interface properties of antibacterial materials for the first time. GIC containing DMADDM can improve material performance and antibacterial properties and may contribute to the better management of secondary caries.

The Use of Quaternary Ammonium to Combat Dental Caries.

Resin composites and adhesives are increasingly popular in dental restorations, but secondary caries is one of the main reasons for restoration failure. Quaternary ammonium monomers (QAMs) have an anti-microbial effect and are widely used in many fields. Since the concept of the immobilized antibacterial effect was put forward, dental restorations containing QAMs have been studied to reduce secondary caries. Previous studies have been struggling to develop novel anti-caries materials which might have triple benefits: good mechanical properties, antibacterial effects and remineralization potentials. Different kinds of QAMs have been proven to be effective in inhibiting the growth and metabolism of biofilms. Combination of QAMs and other nanoparticles in resin composites and adhesives could enhance their anti-caries capability. Therefore, QAMs are promising to show significant impact on the future of restorative and preventive dentistry.

Electrospun gelatin/polycaprolactone nanofibrous membranes combined with a coculture of bone marrow stromal cells and chondrocytes for cartilage engineering.

Electrospinning has recently received considerable attention, showing notable potential as a novel method of scaffold fabrication for cartilage engineering. The aim of this study was to use a coculture strategy of chondrocytes combined with electrospun gelatin/polycaprolactone (GT/PCL) membranes, instead of pure chondrocytes, to evaluate the formation of cartilaginous tissue. We prepared the GT/PCL membranes, seeded bone marrow stromal cell (BMSC)/chondrocyte cocultures (75% BMSCs and 25% chondrocytes) in a sandwich model in vitro, and then implanted the constructs subcutaneously into nude mice for 12 weeks. Gross observation, histological and immunohistological evaluation, glycosaminoglycan analyses, Young's modulus measurement, and immunofluorescence staining were performed postimplantation. We found that the coculture group formed mature cartilage-like tissue, with no statistically significant difference from the chondrocyte group, and labeled BMSCs could differentiate into chondrocyte-like cells under the chondrogenic niche of chondrocytes. This entire strategy indicates that GT/PCL membranes are also a suitable scaffold for stem cell-based cartilage engineering and may provide a potentially clinically feasible approach for cartilage repairs.