The roles of extracellular polymeric substances of Pandoraea sp. XY-2 in the removal of tetracycline.

In this study, the roles of extracellular polymeric substances (EPSs) excreted by Pandoraea sp. XY-2 in the removal of tetracycline (TC) were investigated. In the early stage, TC in the solution was mainly removed by the adsorption of EPSs, which accounted for 20% of TC. Thereafter, large amount of TC was transported into the intracellular and biodegraded. EPSs was extracted and the contents of polyprotein and polysaccharides reached their maximum values (30.84 mg/g and 11.15 mg/g) in the first four days. Fourier transform infrared spectroscopy analysis revealed that hydroxyl, methylidyne, methylene and amide I groups in EPSs participated in the adsorption of TC. Furthermore, three-dimensional excitation-emission matrix fluorescence spectroscopy analysis revealed that TC caused the quenching of EPSs fluorescent groups. The quenching mechanism was attributed to static quenching and protein-like substances in EPSs from Pandoraea sp. XY-2 dominated the TC adsorption process. Bioinformatic analysis of Pandoraea sp. XY-2 genome identified multiple genes involved in exopolysaccharide synthesis and EPSs formation. The insights gained in this study might provide a better understanding about the adsorption process of EPSs in tetracycline-contaminated environment.

Bioinspired Photonic Microchip with Molecularly Imprinted Polymer for Single Recognition of c-Myc Protein in Predictive Medical Diagnostics.

Monitoring of trace c-Myc protein as the biomarker of ubiquitous cancers is critical in achieving predictive medical diagnostics. However, qualitative and quantitative detection of c-Myc protein with superior single selectivity and sensitivity is still challenging. Herein, a bioinspired photonic sensing microchip for single recognition of c-Myc protein is outlined with two synergistic aspects involving chemical and physical design criteria. Chemical design uses specific molecularly imprinted polymer (MIP) with exquisite complementarity in its chemical functions and spatial geometries to targeted c-Myc protein, leading to excellent sensitivity and selectivity for single identification. Physical design involves optical geometrical double-reflection polarization rotation and multilayer interference of the fabricated periodic photonic architecture inspired by Papilio palinurus butterfly wings to enhance the spectral diversity of reflectance. Therefore, a one-of-a-kind sensing platform integrates the advantages of MIP and bioinspired photonic structure is demonstrated to actualize distinctive signal conversion and amplification for qualitative and quantitative detection of trace c-Myc protein, accompanied with superior sensitivity (detection limit is 0.014 µg mL-1 ), selectivity, stability, anti-interference ability as well as rapid response/recovery time. This sensor microchip uniquely ventures into the territory of functionally combining bioinspired photonic structure with MIP absorbers, proven promising for prevention or diagnosis of cancers in medical field.

Influencing factors of psychological pain among older people in China: A cross-sectional study.

Limited research has focused on the psychological pain among older people and factors associated with psychological distress in older adults also remain to be evaluated. This study aims to examine the status and correlates of psychological pain among older people from urban and rural areas in China. This cross-sectional study analyzed data from 4312 samples which extracted from the dataset of China's Health-Related Quality of Life Survey for Older Adults 2018. Psychological pain was assessed by the Chinese version of the Psychache Scale (PAS). Multiple linear regression models were established to examine the associations between demographic characteristics and psychological pain. The average score of PAS among older people was 41.79 ± 14.52, and the average score of PAS among urban older people was higher than rural ones in this study. For rural older people, age (B ≥ 80 = 2.55), gender (B Female = 1.27), educational level (B Primary school = 1.63; B ≥ Middle school = 0.27), smoking (B yes = 0.83), number of chronic diseases (B ≥ 2 = 3.19) and personal social capital (B BRC = 0.27) were positively related to psychological pain, while family per-capita annual income (B15,000-30,000 = -2.52; B > 30,000 = -3.44), living arrangement (B With spouse = -3.40; B With children = -2.89; B Others = -3.82) and personal social capital (B BOC = -0.36) were negatively associated with psychological pain (p < 0.05). Moreover, for urban older people, gender (B Female = 0.98), current occupation (B With occupation = 1.13) and smoking (B yes = 2.14) were positively related to psychological pain, whereas age (B ≥ 80 = -1.45), family per-capita annual income (B > 30,000 = -3.63), living arrangement (B With spouse = -1.31), BMI (Bnormal = -2.62) and personal social capital (B BOC = -0.16) were negatively associated with psychological pain (p < 0.05). The present study sheds light on the worrying state of psychological pain experienced by Chinese older people. The results suggest that targeted interventions and social support, should be taken to alleviate the psychological pain among older people, especially urban older people.

Ginsenoside Rg3 determination using an electro-synthesized molecularly imprinted polymer on MWCNT-Ti3C2Tx nanocomposite modified electrode.

Rare ginsenoside Rg3 is a main active ingredient in ginseng, which is more easily absorbed by human body and plays its role. Determination of Rg3 in edible and medicinal samples is a key factor for quality evaluation and effective monitoring of adulteration. In this study, an electrochemical sensor was developed based on molecularly imprinted polymer (MIP) and nanomaterial amplification. MIP was achieved by electro-polymerization with Rg3 as the template molecule and the functional monomer was o-phenylenediamine. Multi-walled carbon nanotubes (MWCNT) and titanium carbide (Ti3C2Tx) nanocomposites formed an excellent porous structure, which exhibited the advantages of increasing the specific surface area and electrical conductivity. The prepared sensor presented a great linear relation of Rg3 in the range of 10-2000 µg mL-1 with a limit of detection (LOD) of 0.34 µg mL-1. Importantly, the sensor was successfully utilized to detect ginsenoside Rg3 in different real samples.

SaliVISION: a rapid saliva-based COVID-19 screening and diagnostic test with high sensitivity and specificity.

The Coronavirus disease 2019 (COVID-19) pandemic-caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)- has posed a global threat and presented with it a multitude of economic and public-health challenges. Establishing a reliable means of readily available, rapid diagnostic testing is of paramount importance in halting the spread of COVID-19, as governments continue to ease lockdown restrictions. The current standard for laboratory testing utilizes reverse transcription quantitative polymerase chain reaction (RT-qPCR); however, this method presents clear limitations in requiring a longer run-time as well as reduced on-site testing capability. Therefore, we investigated the feasibility of a reverse transcription looped-mediated isothermal amplification (RT-LAMP)-based model of rapid COVID-19 diagnostic testing which allows for less invasive sample collection, named SaliVISION. This novel, two-step, RT-LAMP assay utilizes a customized multiplex primer set specifically targeting SARS-CoV-2 and a visual report system that is ready to interpret within 40 min from the start of sample processing and does not require a BSL-2 level testing environment or special laboratory equipment. When compared to the SalivaDirect and Thermo Fisher Scientific TaqPath RT-qPCR testing platforms, the respective sensitivities of the SaliVISION assay are 94.29% and 98.28% while assay specificity was 100% when compared to either testing platform. Our data illustrate a robust, rapid diagnostic assay in our novel RT-LAMP test design, with potential for greater testing throughput than is currently available through laboratory testing and increased on-site testing capability.

Rapid initiation of a single-stage partial nitritation-anammox process treating low-strength ammonia wastewater: Novel insights into biofilm development on porous polyurethane hydrogel carrier.

Media-supported biofilm is a powerful strategy for growth and enrichment of slow-growing microorganisms. In this study, a single-stage nitritation-anammox process treating low-strength wastewater was successfully started to investigate the biofilm development on porous polyurethane hydrogel carrier. Suspended biomass migration into the carrier and being entrapment by its internal interconnected micropores dominated the fast initial colonization stage. Both surface-attached growth and embedded growth of microbes occurred during the following accumulation stage. Fluorescence in situ hybridization analysis of mature biofilm indicated that ammonium-oxidizing bacteria located at the outer layers featured a surface-attached growth, while anammox microcolonies housed in the inner layers proliferated as an embedded-like growth. In this way, the growth rate of anammox bacteria (predominated by Candidatus Kuenenia) could be 0.079 d-1. The anammox potential of the biofilm reactor reached 1.65 ± 0.3 kg/m3/d within two months. This study provides novel insights into nitritation-anammox biofilm formation on the porous polyurethane hydrogel carrier.

Audiovisual synchrony detection for fluent speech in early childhood: An eye-tracking study.

During childhood, the ability to detect audiovisual synchrony gradually sharpens for simple stimuli such as flashbeeps and single syllables. However, little is known about how children perceive synchrony for natural and continuous speech. This study investigated young children's gaze patterns while they were watching movies of two identical speakers telling stories side by side. Only one speaker's lip movements matched the voices and the other one either led or lagged behind the soundtrack by 600 ms. Children aged 3-6 years (n = 94, 52.13% males) showed an overall preference for the synchronous speaker, with no age-related changes in synchrony-detection sensitivity as indicated by similar gaze patterns across ages. However, viewing time to the synchronous speech was significantly longer in the auditory-leading (AL) condition compared with that in the visual-leading (VL) condition, suggesting asymmetric sensitivities for AL versus VL asynchrony have already been established in early childhood. When further examining gaze patterns on dynamic faces, we found that more attention focused on the mouth region was an adaptive strategy to read visual speech signals and thus associated with increased viewing time of the synchronous videos. Attention to detail, one dimension of autistic traits featured by local processing, has been found to be correlated with worse performances in speech synchrony processing. These findings extended previous research by showing the development of speech synchrony perception in young children, and may have implications for clinical populations (e.g., autism) with impaired multisensory integration.

Nitric Oxide Induces Immunogenic Cell Death and Potentiates Cancer Immunotherapy.

Tumor cells undergoing immunogenic cell death (ICD) release immunogenic damage-associated molecular patterns (DAMPs) to trigger a long-term protective antitumor response. ICD can be induced by certain pathogens, chemotherapeutics, and physical modalities. In this work, we demonstrate that a gaseous molecule, specifically nitric oxide (NO), can induce a potent ICD effect. NO exerts cytotoxic effects that are accompanied by the emission of DAMPs based on the endoplasmic reticulum stress and mitochondrial dysfunction pathways. Released DAMPs elicit immunological protection against a subsequent rechallenge of syngeneic tumor cells in immunocompetent mice. We prepare polynitrosated polyesters with high NO storage capacity through a facile polycondensation reaction followed by a postsynthetic modification. The polynitrosated polyesters-based NO nanogenerator (NanoNO) that enables efficient NO delivery and controlled NO release in tumors induces a sufficient ICD effect. In different immune-intact models of tumors, the NanoNO exhibits significant tumor growth suppression and increases the local dose of immunogenic signals and T cell infiltrations, ultimately prolonging survival. In addition, the NanoNO synergizes with the PD-1 blockade to prevent metastasis. We conclude not only that NO is a potent ICD inducer for cancer immunotherapy but also that it expands the range of ICD inducers into the field of gaseous molecules.

Chemiluminescence sensor for sulfonylurea herbicide using molecular imprinted microspheres as recognition element.

Uniform molecular imprinting microspheres were prepared using precipitation polymerization with thifensulfuron-methyl (TFM) as template, acrylamide as functional monomer and ethylene glycol dimethacrylate as cross-linker. TFM could be selectively adsorbed on the molecularly imprinted polymers (MIPs) matrix through the hydrogen bonding interaction and the adsorbed TFM could be sensed by its strikingly enhancing effect on the weak chemiluminescence (CL) reaction between luminol and hydrogen peroxide. On this basis, a novel CL sensor for the determination of TFM using MIPs as recognition elements was established. The logarithm of net CL intensity (ΔI) is linearly proportional to the logarithm of TFM concentration (C) in the range from 1.0 × 10(-9) to 5.0 × 10(-5) mol L(-1) with a detection limit of 8.3 × 10(-10) mol L(-1) (3σ). The results demonstrated that the MIP-CL sensor was reversible and reusable and that it could strikingly improve the selectivity and sensitivity of CL analysis. Furthermore, it is suggested that the CL enhancement of luminol-H(2)O(2) by TFM might be ascribed to the enhancement effect of CO(2), which came from TFM hydrolysis in basic medium.

Structural stability of novel composite heart valve prostheses - Fatigue and wear performance.

Heart valve replacement is a very effective method to treat severe valvular stenosis or valvular insufficiency. The valve can be divided into the mechanical valve and biological valve according to the main materials of the valve leaflets. The former has good durability, but the patients need to take anticoagulants all their lives, otherwise, thrombosis will occur; the latter has good blood compatibility, and only 3-6 months of postoperative anticoagulation is required, but its durability is lower than the former. Compared with a traditional valve used materials, the fabric composite valve leaflets have both mechanical valve and biological valve advantages, i.e. it can have both good blood compatibility and excellent fatigue resistance. This material is comprised of the internal fabric layer and bilateral external polyurethane layers jointed with adhesive, and it can adjust the flexibility, wear-resistance and fatigue resistance of the valve leaflet through adjusting the thickness of the outer polyurethane protective layer, the weaving method, the fiber diameter and the surface density of the inner ultra-high molecular weight polyethylene (UHMWPE) fabric. In this article, we tested the long-term durability of a fabric composite with its property close to the valve leaflet made of bovine pericardium, to evaluate the material performance loss under long-term fatigue and the wear degree of this material with different polyurethane layer thicknesses. As many as two hundred million cycles of fatigue test and the hydrodynamic performance test before and after the fatigue test proved that the material could withstand a service life of at least five years without structural failure or functional degradation. According to the SEM images after the experiment, it can be predicted that this material can achieve a longer fatigue life.

Dental remineralization via poly(amido amine) and restorative materials containing calcium phosphate nanoparticles.

Tooth decay is prevalent, and secondary caries causes restoration failures, both of which are related to demineralization. There is an urgent need to develop new therapeutic materials with remineralization functions. This article represents the first review on the cutting edge research of poly(amido amine) (PAMAM) in combination with nanoparticles of amorphous calcium phosphate (NACP). PAMAM was excellent nucleation template, and could absorb calcium (Ca) and phosphate (P) ions via its functional groups to activate remineralization. NACP composite and adhesive showed acid-neutralization and Ca and P ion release capabilities. PAMAM+NACP together showed synergistic effects and produced triple benefits: excellent nucleation templates, superior acid-neutralization, and ions release. Therefore, the PAMAM+NACP strategy possessed much greater remineralization capacity than using PAMAM or NACP alone. PAMAM+NACP achieved dentin remineralization even in an acidic solution without any initial Ca and P ions. Besides, the long-term remineralization capability of PAMAM+NACP was established. After prolonged fluid challenge, the immersed PAMAM with the recharged NACP still induced effective dentin mineral regeneration. Furthermore, the hardness of pre-demineralized dentin was increased back to that of healthy dentin, indicating a complete remineralization. Therefore, the novel PAMAM+NACP approach is promising to provide long-term therapeutic effects including tooth remineralization, hardness increase, and caries-inhibition capabilities.

Drug resistance of oral bacteria to new antibacterial dental monomer dimethylaminohexadecyl methacrylate.

Only two reports exist on drug-resistance of quaternary ammonium monomers against oral bacteria; both studies tested planktonic bacteria for 10 passages, and neither study tested biofilms or resins. The objectives of this study were to investigate the drug-resistance of Streptococcus mutans, Streptococcus sanguinis and Streptococcus gordonii against dimethylaminohexadecyl methacrylate (DMAHDM), and to evaluate biofilms on resins with repeated exposures for 20 passages for the first time. DMAHDM, dimethylaminododecyl methacrylate (DMADDM) and chlorhexidine (CHX) were tested with planktonic bacteria. Biofilms were grown on a resin containing 3% DMAHDM. Minimum-inhibitory concentrations were measured. To detect drug-resistance, the survived bacteria from the previous passage were used as inoculum for the next passage for repeated exposures. S. gordonii developed drug-resistance against DMADDM and CHX, but not against DMAHDM. Biofilm colony-forming units (CFU) on DMAHDM-resin was reduced by 3-4 log; there was no difference from passages 1 to 20 (p > 0.1). No drug-resistance to DMAHDM was detected for all three bacterial species. In conclusion, this study showed that DMAHDM induced no drug-resistance, and DMAHDM-resin reduced biofilm CFU by 3-4 log, with no significant change from 1 to 20 passages. DMAHDM with potent antibacterial activities and no drug-resistance is promising for dental applications.

Novel rechargeable calcium phosphate nanoparticle-containing orthodontic cement.

White spot lesions (WSLs), due to enamel demineralization, occur frequently in orthodontic treatment. We recently developed a novel rechargeable dental composite containing nanoparticles of amorphous calcium phosphate (NACP) with long-term calcium (Ca) and phosphate (P) ion release and caries-inhibiting capability. The objectives of this study were to develop the first NACP-rechargeable orthodontic cement and investigate the effects of recharge duration and frequency on the efficacy of ion re-release. The rechargeable cement consisted of pyromellitic glycerol dimethacrylate (PMGDM) and ethoxylated bisphenol A dimethacrylate (EBPADMA). NACP was mixed into the resin at 40% by mass. Specimens were tested for orthodontic bracket shear bond strength (SBS) to enamel, Ca and P ion initial release, recharge and re-release. The new orthodontic cement exhibited an SBS similar to commercial orthodontic cement without CaP release (P>0.1). Specimens after one recharge treatment (e.g., 1 min immersion in recharge solution repeating three times in one day, referred to as "1 min 3 times") exhibited a substantial and continuous re-release of Ca and P ions for 14 days without further recharge. The ion re-release did not decrease with increasing the number of recharge/re-release cycles (P>0.1). The ion re-release concentrations at 14 days versus various recharge treatments were as follows: 1 min 3 times>3 min 2 times>1 min 2 times>6 min 1 time>3 min 1 time>1 min 1 time. In conclusion, although previous studies have shown that NACP nanocomposite remineralized tooth lesions and inhibited caries, the present study developed the first orthodontic cement with Ca and P ion recharge and long-term release capability. This NACP-rechargeable orthodontic cement is a promising therapy to inhibit enamel demineralization and WSLs around orthodontic brackets.

Poly(amido amine) and calcium phosphate nanocomposite remineralization of dentin in acidic solution without calcium phosphate ions.

OBJECTIVE: Patients with dry mouth often have an acidic oral environment lacking saliva that provides calcium (Ca) and phosphate (P) ions. However, there has been no study on dentin remineralization by placing samples in an acidic solution without Ca and P ions. Previous studies used saliva-like solutions with neutral pH and Ca and P ions. Therefore, the objective of this study was to investigate a novel method of combining poly(amido amine) (PAMAM) with a composite of nanoparticles of amorphous calcium phosphate (NACP) on dentin remineralization in an acidic solution without Ca and P ions for the first time. METHODS: Demineralized dentin specimens were tested into four groups: (1) dentin control, (2) dentin coated with PAMAM, (3) dentin with NACP nanocomposite, (4) dentin with PAMAM plus NACP composite. Specimens were treated with lactic acid at pH 4 without initial Ca and P ions for 21 days. Acid neutralization and Ca and P ion concentrations were measured. Dentin specimens were examined by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and hardness testing vs. remineralization efficacy. RESULTS: NACP composite had mechanical properties similar to commercial control composites (p>0.1). NACP composite neutralized acid and released Ca and P ions. PAMAM alone failed to induce dentin remineralization. NACP alone achieved mild remineralization and slightly increased dentin hardness at 21days (p>0.1). In contrast, the PAMAM+NACP nanocomposite method in acid solution without initial Ca and P ions greatly remineralized the pre-demineralized dentin, restoring its hardness to approach that of healthy dentin (p>0.1). SIGNIFICANCE: Dentin remineralization via PAMAM+NACP in pH 4 acid without initial Ca and P ions was demonstrated for the first time, when conventional methods such as PAMAM did not work. The novel PAMAM+NACP nanocomposite method is promising to protect tooth structures, especially for patients with reduced saliva to inhibit caries.

Three-dimensional biofilm properties on dental bonding agent with varying quaternary ammonium charge densities.

OBJECTIVES: Tooth-restoration interfaces are the weak link with secondary caries causing restoration failure. The objectives of this study were to develop an antimicrobial bonding agent with dimethylaminododecyl methacrylate (DMAHDM), and investigate the effects of quaternary amine charge density on three-dimensional (3D) biofilms on dental resin for the first time. METHODS: DMAHDM was synthesized and incorporated into Scotchbond Multi-Purpose bonding agent at mass fractions of 0% (control), 2.5%, 5%, 7.5% and 10%. Streptococcus mutans bacteria were inoculated on the polymerized resin and cultured for two days to form biofilms. Confocal laser scanning microscopy was used to measure biofilm thickness, live and dead biofilm volumes, and live bacteria percentage in 3D biofilm vs. distance from resin surface. RESULTS: Charge density of the resin had a significant effect on the antibacterial efficacy (p<0.05). Biofilms on control resin had the greatest thicknesses. Biofilm thickness and live biofilm volume decreased with increasing surface charge density (p<0.05). There were significant variations in bacterial viability along the 3D biofilm thickness (p<0.05). At 2.5% and 5% DMAHDM, the bacterial inhibition was the greatest on or near the resin surface, and the killing effect decreased away from the resin surface. At 10% DMAHDM, the entire 3D biofilm was dead and the percentage of live bacteria was nearly 0% throughout the biofilm thickness. CONCLUSIONS: Adding new antibacterial monomer DMAHDM into dental bonding agent yielded a strong antimicrobial activity, substantially decreasing the 3D biofilm thickness, live biofilm volume, and percentage of live bacteria on cross-sections through the biofilm thickness. SIGNIFICANCE: Novel DMAHDM-containing bonding agent with capability of inhibiting 3D biofilms is promising for a wide range of dental restorative and preventive applications to inhibit biofilms at the tooth-restoration margins and prevent secondary caries.

Deferoxamine released from poly(lactic-co-glycolic acid) promotes healing of osteoporotic bone defect via enhanced angiogenesis and osteogenesis.

The regeneration capacity of osteoporotic bones is generally lower than that of normal bones. Current methods of osteoporotic bone defect treatment are not always satisfactory. Recent studies demonstrate that activation of the hypoxia inducible factor-1α (HIF-1α) pathway, by genetic methods or hypoxia-mimicking agents, could accelerate bone regeneration. However, little is known as to whether modulating the HIF-1α pathway promotes osteoporotic defect healing. To address this problem in the present study, we first demonstrated that HIF-1α and vascular endothelial growth factor expression levels are lower in osteoporotic bones than in normal bones. Second, we loaded poly(Lactic-co-glycolic acid) (PLGA) with the hypoxia-mimetic agent deferoxamine (DFO). DFO released from PLGA had no significant effect on the proliferation of mesenchymal stem cells (MSCs); however, DFO did enhance the osteogenic differentiation of MSCs. In addition, DFO upregulated the mRNA expression levels of angiogenic factors in MSCs. Endothelial tubule formation assays demonstrate that DFO promoted angiogenesis in human umbilical vein endothelial cells. Third, untreated PLGA scaffolds (PLGA group) or DFO-containing PLGA (PLGA + DFO group) were implanted into critically sized osteoporotic femur defects in ovariectomized rats. After treatment periods of 14 or 28 days, micro-CT, histological, CD31 immunohistochemical, and dynamic bone histomorphometric analyses showed that DFO dramatically stimulated bone formation and angiogenesis in a critically sized osteoporotic femur defect model. Our in vitro and in vivo results demonstrate that DFO may promote the healing of osteoporotic bone defects due to enhanced angiogenesis and osteogenesis. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2515-2527, 2016.

Effect of dimethylaminohexadecyl methacrylate mass fraction on fracture toughness and antibacterial properties of CaP nanocomposite.

OBJECTIVES: Biofilm acids contribute to secondary caries which is a reason for restoration failure. Previous studies synthesized nanoparticles of amorphous calcium phosphate (NACP) and dimethylaminohexadecyl methacrylate (DMAHDM). The objectives of this study were to develop DMAHMD-NACP nanocomposite for double benefits of antibacterial and remineralization capabilities, and investigate the DMAHMD mass fraction effects on fracture toughness and biofilm response of NACP nanocomposite for the first time. METHODS: DMAHDM was incorporated into NACP nanocomposite at mass fractions of 0% (control), 0.75%, 1.5%, 2.25% and 3%. A single edge V-notched beam method was used to measure fracture toughness K(IC). A dental plaque microcosm biofilm model using human saliva as inoculum was used to measure the antibacterial properties of composites. RESULTS: K(IC) was about 1 MPa×m(1/2) for all composite (mean±sd; n=6). Adding DMAHDM from 0% to 3% did not affect K(IC) (p>0.1). Lactic acid production by biofilms on composite containing 3% DMAHDM was reduced to less than 1% of that on composite control. Metabolic activity of adherent biofilms on composite containing 3% DMAHDM was reduced to 4% of that on composite control. Biofilm colony-forming unit (CFU) counts were reduced by three orders of magnitude on NACP nanocomposite containing 3% DMAHDM. CONCLUSIONS: DMAHDM-NACP nanocomposite had good fracture resistance, strong antibacterial potency, and NACP for remineralization (shown in previous studies). The DMAHDM-NACP nanocomposite may be promising for caries-inhibiting dental restorations, and the method of using double agents (DMAHDM and NACP) may have a wide applicability to other dental materials including bonding agents and cements.

Linear polyethylenimine-plasmid DNA nanoparticles are ototoxic to the cultured sensory epithelium of neonatal mice.

Polyethylenimine (PEI) has been demonstrated to be an effective non­viral synthetic polymer for efficient gene delivery amongst various cell types in vitro and in vivo. In the present study, 25 kDa linear PEI (L­PEI) was used to transfer plasmid DNA (pDNA), encoding the enhanced green fluorescent protein reporter gene, into the cultured cochlear epithelium of neonatal mice. The 25 kDa L­PEI/pDNA nanoparticles were generated in phosphate­buffered saline prior to transfection. Sensory epithelial cells were transfected using an appropriate weight ratio of L­PEI and pDNA. However, the use of higher L­PEI/pDNA ratios, which result in the generation of a greater number of nanoparticles, induced significant damage to the sensory epithelial cells, as demonstrated by immunofluorescent and transmission electron microscopy analyses. These results indicated that precautionary measures are required with regard to the use of PEI nanoparticles in nanomedicine, and emphasized the requirement for thorough physicochemical characterization and toxicity testing for each polymer vector prior to the construction of nanotechnology systems for use in clinical applications. The development of effective management techniques for potential nano­ototoxicity risks is of considerable significance to the clinical applications of nanoparticles.

Dental plaque microcosm response to bonding agents containing quaternary ammonium methacrylates with different chain lengths and charge densities.

OBJECTIVES: Antibacterial bonding agents are promising to combat bacteria and caries at tooth-restoration margins. The objectives of this study were to incorporate new quaternary ammonium methacrylates (QAMs) to bonding agent and determine the effects of alkyl chain length (CL) and quaternary amine charge density on dental plaque microcosm bacteria response for the first time. METHODS: Six QAMs were synthesized with CL=3, 6, 9, 12, 16, 18. Each QAM was incorporated into Scotchbond multi-purpose (SBMP). To determine the charge density effect, dimethylaminododecyl methacrylate (DMAHDM, CL=16) was mixed into SBMP at mass fraction=0%, 2.5%, 5%, 7.5%, 10%. Charge density was measured using a fluorescein dye method. Dental plaque microcosm using saliva from ten donors was tested. Bacteria were inoculated on resins. Early-attachment was tested at 4h. Biofilm colony-forming units (CFU) were measured at 2 days. RESULTS: Incorporating QAMs into SBMP reduced bacteria early-attachment. Microcosm biofilm CFU for CL=16 was 4 log lower than SBMP control. Charge density of bonding agent increased with DMAHDM content. Bacteria early-attachment decreased with increasing charge density. Biofilm CFU at 10% DMAHDM was reduced by 4 log. The killing effect was similarly-strong against total microorganisms, total streptococci, and mutans streptococci. CONCLUSIONS: Increasing alkyl chain length and charge density of bonding agent was shown for the first time to decrease microcosm bacteria attachment and reduce biofilm CFU by 4 orders of magnitude. Novel antibacterial resins with tailored chain length and charge density are promising for wide applications in bonding, cements, sealants and composites to inhibit biofilms and caries.