Deficiency of Fam20b-Catalyzed Glycosaminoglycan Chain Synthesis in Neural Crest Leads to Cleft Palate.

Cleft palate is one of the most common birth defects. Previous studies revealed that multiple factors, including impaired intracellular or intercellular signals, and incoordination of oral organs led to cleft palate, but were little concerned about the contribution of the extracellular matrix (ECM) during palatogenesis. Proteoglycans (PGs) are one of the important macromolecules in the ECM. They exert biological functions through one or more glycosaminoglycan (GAG) chains attached to core proteins. The family with sequence similarity 20 member b (Fam20b) are newly identified kinase-phosphorylating xylose residues that promote the correct assembly of the tetrasaccharide linkage region by creating a premise for GAG chain elongation. In this study, we explored the function of GAG chains in palate development through Wnt1-Cre; Fam20bf/f mice, which exhibited complete cleft palate, malformed tongue, and micrognathia. In contrast, Osr2-Cre; Fam20bf/f mice, in which Fam20b was deleted only in palatal mesenchyme, showed no abnormality, suggesting that failed palatal elevation in Wnt1-Cre; Fam20bf/f mice was secondary to micrognathia. In addition, the reduced GAG chains promoted the apoptosis of palatal cells, primarily resulting in reduced cell density and decreased palatal volume. The suppressed BMP signaling and reduced mineralization indicated an impaired osteogenesis of palatine, which could be rescued partially by constitutively active Bmpr1a. Together, our study highlighted the key role of GAG chains in palate morphogenesis.

Discovery of myricetin as an inhibitor against Streptococcus mutans and an anti-adhesion approach to biofilm formation.

Streptococcus mutans (S. mutans) are cariogenic microorganisms. Sortase A (SrtA) is a transpeptidase that attaches Pac to the cell surface. The biofilm formation of S. mutans is promoted by SrtA regulated Pac. Myricetin (Myr) has a variety of pharmacological properties, including inhibiting SrtA activity of Staphylococcus aureus. The purpose of this research was to investigate the inhibitory effect of Myr on SrtA of S. mutans and its subsequent influence on the biofilm formation. Here, Myr was discovered as a potent inhibitor of S. mutans SrtA, with an IC50 of 48.66 ± 1.48 µM, which was lower than the minimum inhibitory concentration (MIC) of 512 ug/mL. Additionally, immunoblot and biofilm assays demonstrated that Myr at a sub-MIC level could reduce adhesion and biofilm formation of S. mutans. The reduction of biofilm was possibly caused by the decreased amount of Pac on the cells' surface by releasing Pac into the medium via inhibiting SrtA activity. Molecular dynamics simulations and mutagenesis assays suggested that Met123, Ile191, and Arg213 of SrtA were pivotal for the interaction of SrtA and Myr. Our findings indicate that Myr is a promising candidate for the control of dental caries by modulating Pac-involved adhesive mechanisms without developing drug resistance to S.mutans.

Tissue interactions are indispensable for cavity formation and disc separation in the temporomandibular joint.

Purpose: Our previous study found that in the temporomandibular joint (TMJ) of the K14-cre; Ctnnb1ex3f mouse embryo, the morphogenesis of glenoid fossa was interrupted by the dislocated condyle. This observation suggested that the formation of the glenoid fossa required tissue interactions with condylar mesenchyme. The purpose of this study was to clarify if the interactions between other components are essential for TMJ morphogenesis.Materials and methods: We examined the gross morphology, histology, cell proliferation, and gene expression in the developing TMJ of K14-cre; Ctnnb1ex3f mice by whole-mount bone and cartilage staining, Azon staining, BrdU labeling, and in situ hybridization, respectively.Results: In K14-cre; Ctnnb1ex3f mice, the zygomatic arch was misconnected to the mandibular bone by ectopic bone formation, which disrupted the attachment of temporalis to the mandibular bone and joint capsule formation. Although the initiation and differentiation of the condylar cartilage were slightly impacted, the K14-cre; Ctnnb1ex3f TMJ lacked joint cavities and separated disc, suggesting that the tissue interactions between the joint capsule and the TMJ were indispensable for the cavity formation and disc separation. The ectopic activation of Gli2 in the cells occupying the cavities, and the enhanced PTHrP transcription in the condylar perichondrium of the K14-cre; Ctnnb1ex3f TMJ suggested that the disrupted interactions between the joint capsule and the TMJ impaired cavity formation and disc separation by altering Hh signaling.Conclusion: Joint capsule formation was essential for cavity formation and disc separation during TMJ development.

BpNAC012 Positively Regulates Abiotic Stress Responses and Secondary Wall Biosynthesis.

NAC (NAM, ATAF1/2, and CUC2) transcription factors play important roles in plant biological processes and stress responses. Here, we characterized the functional roles of BpNAC012 in white birch (Betula platyphylla). We found that BpNAC012 serves as a transcriptional activator. Gain- and loss-of-function analyses revealed that the transcript level of BpNAC012 was positively associated with salt and osmotic stress tolerance. BpNAC012 activated the core sequence CGT[G/A] to induce the expression of abiotic stress-responsive downstream genes, including Δ-1-pyrroline-5-carboxylate synthetase, superoxide dismutase, and peroxidase, resulting in enhanced salt and osmotic stress tolerance in BpNAC012 overexpression transgenic birch lines. We also showed that BpNAC012 is expressed predominantly in mature stems and that RNA interference-induced suppression of BpNAC012 caused a drastic reduction in the secondary wall thickening of stem fibers. Overexpression of BpNAC012 activated the expression of secondary wall-associated downstream genes by directly binding to the secondary wall NAC-binding element sites, resulting in ectopic secondary wall deposition in the stem epidermis. Moreover, salt and osmotic stresses elicited higher expression levels of lignin biosynthetic genes and elevated lignin accumulation in BpNAC012 overexpression lines. These findings provide insight into the functions of NAC transcription factors.

Nanostructure of DiR-Loaded Solid Lipid Nanoparticles with Potential Bioimaging Functions.

The fluorescence dye-loaded nanoparticles are widely used as bioimaging agents in the field of nanotheranostics. However, the nanoparticles for nanotheranostics usually consist of synthetic materials, such as metal, silica, and organic polymers, which are often biologically incompatible and may arouse toxicity issues. Herein, the potential of near-infrared probe DiR-containing solid lipid nanoparticle suspensions (DiR-SLNS) as the bioimaging agent, which was prepared by lipids and surfactants with excellent biocompatibility, was investigated in this study. The nanostructure of DIR-SLNS system and the distribution of DiR were studied by dissipative particle dynamics (DPD) simulations. The stability of physicochemical properties and fluorescence spectra of DIR-SLNS system were investigated using dynamic laser scattering (DLS), nanoparticle tracking analysis (NTA), and fluorescence spectra. The fluorescence intensity-concentration correlation of DIR-SLNS was also evaluated. As a result, DiR-SLNS demonstrated a "core-shell"-like nanostructure and DiR was mainly distributed in the cetyl palmitate (CP) core rather than the surface of SLNS, which was beneficial to its potential applications in bioimaging. DiR-SLNS exhibited remarkable physicochemical stability as the nanoparticles maintained ~ 90% fluorescence intensity during the 10-day storage time. The correlation between fluorescence intensity and concentration was established and validated using a linear regression model. This study proposed a type of promising candidates in nano-scale with higher safety and fluorescence stability for bioimaging.

Long noncoding RNA C21orf121/bone morphogenetic protein 2/microRNA-140-5p gene network promotes directed differentiation of stem cells from human exfoliated deciduous teeth to neuronal cells.

Previous studies have revealed that long noncoding RNA (lncRNA) and microRNA play a crucial role in autism, which is a childhood neurodevelopmental disorder with complicated genetic origins. Hence, the study concerns whether lncRNA C21orf121/bone morphogenetic proteins 2 (BMP2)/miR-140-5p gene network affects directed differentiation of stem cells from human exfoliated deciduous teeth (SHED) to neuronal cells in rats with autism. Autism models were successfully established. The neuron cells that differentiated from SHED cell were identified. The expression of lncRNA C21orf121, miR-140-5p, BMP2, Nestin, ßIII-tubulin, and microtubule-associated protein 2 (MAP2) and the expression of neuron-specific enolase (NSE) were examined. Besides, the gap junction (GJ) function of SHED, the intracellular free Ca 2+ concentration, and the social behavior and repetitive stereotyped movements of rats in autism were detected. The target relationship between lncRNA C21orf121 and miR-140-5p and that between miR-140-5p and BMP2 were also verified. Firstly, we successfully isolated SHED and identified the differentiated neurons of SHED. Besides, the expression of BMP2, MAP2, Nestin, ßIII-tubulin, NSE positive rate, GJ function, and intracellular free Ca 2+ concentration were increased with the upregulation of C21orf121 and downregulation of miR-140-5p, and accumulated time of repetitive stereotyped movements decreased and the frequency of social behavior increased. The results indicate that lncRNA C21orf121 as a competing endogenous RNA competes with BMP2 binding to miR-140-5p, thereby promoting SHED to differentiate into neuronal cells via upregulating BMP2 expression.

Prediction Model of Cardiac Risk for Dental Extraction in Elderly Patients with Cardiovascular Diseases.

BACKGROUND: With the rapidly increasing population of elderly people, dental extraction in elderly individuals with cardiovascular diseases (CVDs) has become quite common. The issue of how to assure the safety of elderly patients with CVDs undergoing dental extraction has perplexed dentists and internists for many years. And it is important to derive an appropriate risk prediction tool for this population. OBJECTIVES: The aim of this retrospective, observational study was to establish and validate a prediction model based on the random forest (RF) algorithm for the risk of cardiac complications of dental extraction in elderly patients with CVDs. METHODS: Between August 2017 and May 2018, a total of 603 patients who fulfilled the inclusion criteria were used to create a training set. An independent test set contained 230 patients between June 2018 and July 2018. Data regarding clinical parameters, laboratory tests, clinical examinations before dental extraction, and 1-week follow-up were retrieved. Predictors were identified by using logistic regression (LR) with penalized LASSO (least absolute shrinkage and selection operator) variable selection. Then, a prediction model was constructed based on the RF algorithm by using a 5-fold cross-validation method. RESULTS: The training set, based on 603 participants, including 282 men and 321 women, had an average participant age of 72.38 ± 8.31 years. Using feature selection methods, 11 predictors for risk of cardiac complications were screened out. When the RF model was constructed, its overall classification accuracy was 0.82 at the optimal cutoff value of 18.5%. In comparison to the LR model, the RF model showed a superior predictive performance. The AUROC (area under the receiver operating characteristic curve) scores of the RF and LR models were 0.83 and 0.80, respectively, in the independent test set. The AUPRC (area under the precision-recall curve) scores of the RF and LR models were 0.56 and 0.35, respectively, in the independent test set. CONCLUSION: The RF-based prediction model is expected to be applicable for preoperative clinical assessment for preventing cardiac complications in elderly patients with CVDs undergoing dental extraction. The findings may aid physicians and dentists in making more informed recommendations to prevent cardiac complications in this patient population.

An NIR-Guided Aggregative and Self-Immolative Nanosystem for Efficient Cancer Targeting and Combination Anticancer Therapy.

Nanosized drug delivery systems based on polymeric structures have been proven to be promising approaches for cancer treatments. However, few have been effective at selectively targeting cancer cells and releasing drug at desired tumor sites. Here, we report a "smart" polymeric nanoplatform, which could actively accumulate at tumor sites and dissociate to release encapsulated cargos upon the irradiation of a near-infrared (NIR) laser. This nanoplatform composed of a novel amphiphilic block copolymer poly(propylene sulfide)-poly( N-isopropylacrylamide- co- N, N-dimethylacrylamide) (PPS-P(NIPAM- co-DMAA)) formed spherical structures in aqueous solution and responded to both oxidants and elevated temperature. Upon laser irradiation at 808 nm, the NIR light was efficiently converted to local heat by the doxorubicin (DOX) and indocyanine green (ICG) co-loaded micelles for enhanced cell uptake and therapeutic efficacy. It showed that the micelles effectively accumulated at the tumor sites guided by the application of an NIR laser in in vivo studies, exhibiting a 6-time greater and much faster targeting effect compared to the nonirradiation group. The effective tumor growth inhibition by the drug-loaded micelles upon laser irradiation demonstrated significant tumor inhibition without regrowth in 16 days. This micellar nanoplatform for precise NIR-guided cancer targeting and combination therapy provides a novel and robust strategy for cancer therapy.

Tilianin-loaded Reactive Oxygen Species-Scavenging Nano-Micelles Protect H9c2 Cardiomyocyte Against Hypoxia/Reoxygenation-Induced Injury.

Previous studies have shown that tilianin alleviates ischemia-reperfusion-induced cardiomyocyte injury. However, its clinical translation has been hampered because of its insolubility in water. Tilianin-based nano-micelles that may overcome this critical issue are presented. A polyethylene glycol compound was covalently attached to propylene sulfide-formed amphiphilic diblock polymers. In the aqueous solution, tilianin is encapsulated in a hydrophobic shell to form nano-micelles. The Ph-PPS-PEG self-assembled into nanoscale micelles with a size of approximately 70 nm, termed "tilianin-loaded micelles" (TLMs). TLMs are highly efficient hydrogen peroxide scavengers and the activity of caspase-3 inhibition, thereby protecting cells from H/R-induced cytotoxicity. In addition, TLMs decreased levels of MDA, IL-1 and tumor necrosis factor (TNF-α), inhibited apoptosis, TLR4 and nuclear transcription factor (NF-κB p65) protein expression in hypoxia-reoxygenation (H/R) model. Taken together, the study suggests that TLMs may be of clinical value for the protective effects of cardiomyocytes by inhibiting Inflammation and oxidative stress during myocardial ischemia-reperfusion injury.

Clinical effects of stannous fluoride dentifrice in reducing plaque microbial virulence III: Lipopolysaccharide and TLR2 reporter cell gene activation.

PURPOSE: This study expanded the analysis of subgingival dental plaques from previous research to include the evaluation of cohort, site and treatment effects on chemically measured endotoxin and activation of Toll-like receptor (TLR) based gene expression in two additional reporter cell lines: a TLR2 specific cell line and a THP-1 (multi TLR reporter) cell line. METHODS: Participants from high and low bleeding cohorts were sampled at baseline for both supra and subgingival dental plaque at both healthy as well as clinically diseased sites and then provided with intervention hygiene products including a stabilized SnF2 dentifrice and a new soft bristle manual toothbrush. Following 2 and 4 weeks of assigned dentifrice use, participants returned for a re-evaluation of gingival inflammation and bleeding and repeat samplings of dental plaque. Subgingival sampled plaques were chemically analyzed for endotoxin concentration using a Thermo Scientific Pierce LAL chromogenic endotoxin quantitation kit. Samples were also used for inoculation of two reporter cell assays (an HEK293 TLR2 reporter cell line and a THP-1 monocyte cell line). Reporter cell activation was analyzed via luminescence changes of secreted embryonic alkaline phosphatase. RESULTS: The endotoxin content of subgingival plaque could be measured directly with dye assays and plaque isolates activated gene expression in both TLR reporter cell lines. Higher disease cohorts and sites with gingival inflammation generally showed more endotoxins and higher levels of plaque virulence as compared to low disease cohorts or plaque sampled from clinically healthy sites. SnF2 dentifrice treatment was associated with broad scale reductions in endotoxin content and virulence potentiation properties of dental plaque samples collected subgingivally from patients. CLINICAL SIGNIFICANCE: These results collectively support the use of dye or various reporter cell lines in the characterization of plaque virulence in diseased populations and as a potential route for analysis in clinical evaluations of treatment interventions. Subgingival plaque 'detoxification' including effects on microbial pathogenicity as well as metabolic activity may be considered important mechanisms contributing to clinical benefits of SnF2 dentifrice.

Expression of the MYB transcription factor gene BplMYB46 affects abiotic stress tolerance and secondary cell wall deposition in Betula platyphylla.

Plant MYB transcription factors control diverse biological processes, such as differentiation, development and abiotic stress responses. In this study, we characterized BplMYB46, an MYB gene from Betula platyphylla (birch) that is involved in both abiotic stress tolerance and secondary wall biosynthesis. BplMYB46 can act as a transcriptional activator in yeast and tobacco. We generated transgenic birch plants with overexpressing or silencing of BplMYB46 and subjected them to gain- or loss-of-function analysis. The results suggest that BplMYB46 improves salt and osmotic tolerance by affecting the expression of genes including SOD, POD and P5CS to increase both reactive oxygen species scavenging and proline levels. In addition, BplMYB46 appears to be involved in controlling stomatal aperture to reduce water loss. Overexpression of BplMYB46 increases lignin deposition, secondary cell wall thickness and the expression of genes in secondary cell wall formation. Further analysis indicated that BplMYB46 binds to MYBCORE and AC-box motifs and may directly activate the expression of genes involved in abiotic stress responses and secondary cell wall biosynthesis whose promoters contain these motifs. The transgenic BplMYB46-overexpressing birch plants, which have improved salt and osmotic stress tolerance, higher lignin and cellulose content and lower hemicellulose content than the control, have potential applications in the forestry industry.

Polymeric micelles with dual thermal and reactive oxygen species (ROS)-responsiveness for inflammatory cancer cell delivery.

BACKGROUND: The object of this study was to develop a thermally and reactive oxygen species-responsive nanocarrier system for cancer therapy. RESULTS: PPS-PNIPAm block copolymer was designed and synthesised using a combination of living anionic ring-opening polymerization and atom transfer radical polymerization. The synthesized polymer formed micellar aggregates in water and demonstrated dual responsiveness towards temperature and oxidants. Using doxorubicin (DOX) as a model drug, encapsulation and in vitro release of the drug molecules in PPS-PNIPAm nanocarriers confirmed the responsive release properties of such system. Cell uptake of the DOX loaded micelles was investigated with human breast cancer cell line (MCF-7). The results showed Dox-loaded micelles were able to be taken by the cells and mainly reside in the cytoplasma. In the stimulated cells with an elevated level of ROS, more released DOX was observed around the nuclei. In the cytotoxicity experiments, the Dox-loaded micelles demonstrated comparable efficacy to free DOX at higher concentrations, especially on ROS stimulated cells. CONCLUSIONS: These results demonstrated that PPS-PNIPAm nanocarriers possess the capability to respond two typical stimuli in inflammatory cells: temperature and oxidants and can be used in anticancer drug delivery.

Dissecting a complex chemical stress: chemogenomic profiling of plant hydrolysates.

The efficient production of biofuels from cellulosic feedstocks will require the efficient fermentation of the sugars in hydrolyzed plant material. Unfortunately, plant hydrolysates also contain many compounds that inhibit microbial growth and fermentation. We used DNA-barcoded mutant libraries to identify genes that are important for hydrolysate tolerance in both Zymomonas mobilis (44 genes) and Saccharomyces cerevisiae (99 genes). Overexpression of a Z. mobilis tolerance gene of unknown function (ZMO1875) improved its specific ethanol productivity 2.4-fold in the presence of miscanthus hydrolysate. However, a mixture of 37 hydrolysate-derived inhibitors was not sufficient to explain the fitness profile of plant hydrolysate. To deconstruct the fitness profile of hydrolysate, we profiled the 37 inhibitors against a library of Z. mobilis mutants and we modeled fitness in hydrolysate as a mixture of fitness in its components. By examining outliers in this model, we identified methylglyoxal as a previously unknown component of hydrolysate. Our work provides a general strategy to dissect how microbes respond to a complex chemical stress and should enable further engineering of hydrolysate tolerance.

Morin inhibits sortase A and subsequent biofilm formation in Streptococcus mutans.

Streptococcus mutans (S. mutans) is the main etiological agent of dental caries, and adheres to the tooth surface through the sortase A (SrtA)-mediated cell wall-anchored protein Pac. Inhibition of SrtA activity results in a marked reduction in the adhesion potential of S. mutans, and the frequency of dental caries. Morin is a natural plant extract that was previously reported to inhibit Staphylococcus aureus SrtA activity. Here, we demonstrate that morin has an inhibitory effect against S. mutans UA159 SrtA, with an IC50 of 27.2 ± 2.6 µM. Western blotting demonstrated that 30 µM morin induced the partial release of the Pac protein into the supernatant. The biofilm mass of S. mutans was reduced in the presence of 30 µM morin, which was not caused by a decrease in S. mutans viability. These results indicate that morin might be important as a new agent to prevent caries.

Visualization and correlation of drug release of risperidone/clozapine microspheres in vitro and in vivo based on FRET mechanism.

This study addresses the challenging task of quantitatively investigating drug release from PLGA microspheres after in vivo administration. The objective is to employ Förster resonance energy transfer (FRET) to visualize drug-encapsulated microspheres in both in vitro and in vivo settings. The primary goal is to establish a quantitative correlation between FRET fluorescence changes and microsphere drug release. The study selects drugs with diverse structures and lipid solubility to explore release mechanisms, using PLGA as the matrix material. Clozapine and risperidone serve as model drugs. FRET molecules, Cy5 and Cy5.5, along with Cy7 derivatives, create FRET donor-acceptor pairs. In vitro results show that FRET fluorescence changes align closely with microsphere drug release, particularly for the Cy5.5-Cy7 pair. In vivo experiments involve subcutaneous administration of microspheres to rats, tracking FRET fluorescence changes while collecting blood samples. Pharmacokinetic studies on clozapine and risperidone reveal in vivo absorption fractions using the Loo-Riegelman method. Correlating FRET and in vivo absorption data establishes an in vitro-in vivo relationship (IVIVR). The study demonstrates that FRET-based fluorescence changes quantitatively link to microsphere drug release, offering an innovative method for visualizing and monitoring release in both in vitro and in vivo settings, potentially advancing clinical applications of such formulations.

Curcumin attenuates cyclooxygenase-2 expression via inhibition of the NF-κB pathway in lipopolysaccharide-stimulated human gingival fibroblasts.

Porphyromonas gingivalis lipopolysaccharide (LPS) induces the expression of the cyclooxygenase-2 (COX-2), which contributes to the process of periodontitis. Curcumin, a constituent of turmeric, exhibits anti-inflammatory properties. We have investigated the anti-inflammatory effect of curcumin in human gingival fibroblasts (HGFs) stimulated by P. gingivalis LPS and its mechanism of action. HGFs pretreated with curcumin were stimulated by P. gingivalis LPS. COX-2 mRNA and protein expressions were analysed by real-time PCR and Western blot analysis. Activation of nuclear factor kappa B (NF-κB) was analysed by the NF-κB-dependent luciferase activity and electrophoretic mobility-shift assay (EMSA). Curcumin inhibited COX-2 mRNA and protein synthesis in LPS-stimulated HGFs in a dose-dependent manner. P. gingivalis LPS activated NF-κB-dependent transcription in HGFs, which were also downregulated by pretreatment with curcumin. Therefore, curcumin can inhibit P. gingivalis LPS-induced COX-2 expression, which may be due to the inhibition of the NF-κB pathway.

Prion protein: structural features and related toxicity.

Transmissible spongiform encephalopathies, or prion diseases, is a group of infectious neurodegenerative disorders. The conformational conversion from cellular form (PrP(C)) to disease-causing isoform (PrP(Sc)) is considered to be the most important and remarkable event in these diseases, while accumulation of PrP(Sc) is thought to be the main reason for cell death, inflammation and spongiform degeneration observed in infected individuals. Although these rare but unique neurodegenerative disorders have attracted much attention, there are still many questions that remain to be answered. Knowledge of the scrapie agent structures and the toxic species may have significance for understanding the causes of the diseases, and could be helpful for rational design of novel therapeutic and diagnostic methods. In this review, we summarized the available experimental evidence concerning the relationship among the structural features, aggregation status of misfolded PrP and related neurotoxicity in the course of prion diseases development. In particular, most data supports the idea that the smaller oligomeric PrP(Sc) aggregates, rather than the mature amyloid fibers, exhibit the highest toxicity to the host.

Comparative study of three types of polymer materials co-cultured with bone marrow mesenchymal stem cells for use as a myocardial patch in cardiomyocyte regeneration.

The purpose of this study was to investigate the most suitable polymer material for supporting stem cell growth as a myocardial patch. After cell isolation and expansion of mouse bone marrow mesenchymal stem cells (BMSC), the cells were induced to differentiate into cardiomyocytes with 5-azacytidine to determine their differentiation potential. BMSCs were also seeded onto three types of polymer material film, including polyurethane (PU), 3-hydroxybutyrate-co-4-hydroxybutyrate [P(3HB-co-4HB)], and polypropylene carbonate (PPC). The results revealed that cell numbers were more abundant on both the PU and P(3HB-co-4HB) material surfaces. Conversely, the surface of PPC was smooth with only cell lysate debris observed. The average cell counts were as follows: 143.78 ± 38.38 (PU group), 159.50 ± 33.07 [P(3HB-co-4HB) group], and 1.40 ± 0.70 (PPC group). There was no statistically significant difference in cell numbers between the PU and P(3HB-co-4HB) groups. A statistically significant difference was identified between the PPC group and both the PU (P1) and P(3HB-co-4HB) groups (P2). Polymer biomaterial patches composed of PU and P(3HB-co-4HB) permit good stem cell growth. P(3HB-co-4HB) has the potential for development as a clinical alternative to current treatment methods for the regeneration of cardiomyocytes in patients with myocardial infarction.

Mode-converted diffuse ultrasonic backscatter.

Diffuse ultrasonic backscatter describes the scattering of elastic waves from interfaces within heterogeneous materials. Previously, theoretical models have been developed for the diffuse backscatter of longitudinal-to-longitudinal (L-L) wave scattering within polycrystalline materials. Following a similar formalism, a mode-conversion scattering model is presented here to quantify the component of an incident longitudinal wave that scatters and is converted to a transverse (shear) wave within a polycrystalline sample. The model is then used to fit experimental measurements associated with a pitch-catch transducer configuration performed using a sample of 1040 steel. From these measurements, an average material correlation length is determined. This value is found to be in agreement with results from L-L scattering measurements and is on the order of the grain size as determined from optical micrographs. Mode-converted ultrasonic backscatter is influenced much less by the front-wall reflection than an L-L measurement and it provides additional microstructural information that is not accessible in any other manner.

Anti-freezing dual-network hydrogels with high-strength, self-adhesive and strain-sensitive for flexible sensors.

Hydrogels as flexible sensor have attracted significant attention due to its conductivity, stretchability and flexibility. However, it is still a great challenge to prepare hydrogels that simultaneously possess high strength, anti-fatigue, self-adhesion, and anti-freezing. Herein, a multifunctional dual-network hydrogel was prepared by in situ polymerization of acrylic monomer in chitosan chains, and coordinated with aluminum chloride and glycerol. Based on chain entanglement, hydrogen bonding and coordination interactions, this dual-network hydrogel exhibited excellent mechanical properties, good fatigue resistance, and excellent adhesion performance. It can be used as a strain sensor for its stable conductivity and high sensitivity, which could monitor both large human motions and subtle motions. Due to the presence of glycerol, the hydrogel showed outstanding freezing resistance and still kept flexible and conductive even at low temperatures (-20 °C). This hydrogel can be applied as a flexible wearable sensor for monitoring human motion in extreme low-temperature condition.