Revealing Metabolic Dysregulation Induced by Polypropylene Nano- and Microplastics in Nile Tilapia via Noninvasive Probing Epidermal Mucus.

A noninvasive sampling technology was conceived, employing a disposable acupuncture needle in conjunction with high-resolution mass spectrometry (termed as noninvasive direct sampling extractive electrospray ionization mass spectrometry, NIDS-EESI-MS) to scrutinize the epidermal mucus of Nile tilapia for insights into the metabolic dysregulation induced by polypropylene nano- and microplastics. This analytical method initiates with the dispensing of an extraction solvent onto the needles coated with the mucus sample, almost simultaneously applying a high voltage to generate analyte ions. This innovative strategy obliterates the necessitation for laborious sample preparation, thereby simplifying the sampling process. Employing this technique facilitated the delineation of a plethora of metabolites, encompassing, but not confined to, amino acids, peptides, carbohydrates, ketones, fatty acids, and their derivatives. Follow-up pathway enrichment analysis exposed notable alterations within key metabolic pathways, including the biosynthesis of phenylalanine, tyrosine, and tryptophan, lysine degradation, as well as the biosynthesis and metabolism of valine, leucine, and isoleucine pathways in Nile tilapia, consequent to increased concentrations of polypropylene nanoplastics. These metabolic alterations portend potential implications such as immune suppression, among other deleterious outcomes. This trailblazing application of this methodology not only spares aquatic life from sacrifice but also inaugurates an ethical paradigm for conducting longitudinal studies on the same organisms, facilitating detailed investigations into the long-term effects of environmental pollutants. This technique enhances the ability to observe and understand the subtle yet significant impacts of such contaminants over time.

Computational analysis of curcumin-mediated alleviation of inflammation in periodontitis patients with experimental validation in mice.

AIM: Using network pharmacology and experimental validation to explore the therapeutic efficacy and mechanism of curcumin (Cur) in periodontitis treatment. MATERIALS AND METHODS: Network pharmacology was utilized to predict target gene interactions of Cur-Periodontitis. Molecular docking was used to investigate the binding affinity of Cur for the predicted targets. A mouse model with ligature-induced periodontitis (LIP) was used to verify the therapeutic effect of Cur. Microcomputed tomography (micro-CT) was used to evaluate alveolar bone resorption, while western blotting, haematoxylin-eosin staining and immunohistochemistry were used to analyse the change in immunopathology. SYTOX Green staining was used to assess the in vitro effect of Cur in a mouse bone marrow-isolated neutrophil model exposed to lipopolysaccharide. RESULTS: Network pharmacology identified 114 potential target genes. Enrichment analysis showed that Cur can modulate the production of neutrophil extracellular traps (NETs). Molecular docking experiments suggested that Cur effectively binds to neutrophil elastase (ELANE), peptidylarginine deiminase 4 (PAD4) and cathepsin G, three enzymes involved in NETs. In LIP mice, Cur alleviated alveolar bone resorption and reduced the expression of ELANE and PAD4 in a time-dependent but dose-independent manner. Cur can directly inhibit NET formation in the cell model. CONCLUSIONS: Our research suggested that Cur may alleviate experimental periodontitis by inhibiting NET formation.

Quercetin promotes autophagy to alleviate cigarette smoke-related periodontitis.

BACKGROUND AND OBJECTIVES: Cigarette smoking has been reported as an independent risk factor for periodontitis. Tobacco toxins affect periodontal tissue not only locally but also systemically, leading to the deterioration and recurrence of periodontitis. However, the mechanism of cigarette smoke-related periodontitis (CSRP) is unclear and thus lacks targeted treatment strategies. Quercetin, a plant-derived polyphenolic flavonoid, has been reported to have therapeutic effects on periodontitis due to its documented antioxidant activity. This study aimed to evaluate the effects of quercetin on CSRP and elucidated the underlying mechanism. METHODS: The cigarette smoke-related ligature-induced periodontitis mouse model was established by intraperitoneal injection of cigarette smoke extract (CSE) and silk ligation of bilateral maxillary second molars. Quercetin was adopted by gavage as a therapeutic strategy. Micro-computed tomography was used to evaluate the alveolar bone resorption. Immunohistochemistry detected the oxidative stress and autophagy markers in vivo. Cell viability was determined by Cell Counting Kit-8, and oxidative stress levels were tested by 2,7-dichlorodihydrofluorescein diacetate probe and lipid peroxidation malondialdehyde assay kit. Alkaline phosphatase and alizarin red staining were used to determine osteogenic differentiation. Network pharmacology analysis, molecular docking, and western blot were utilized to elucidate the underlying molecular mechanism. RESULTS: Alveolar bone resorption was exacerbated and oxidative stress products were accumulated during CSE exposure in vivo. Oxidative stress damage induced by CSE caused inhibition of osteogenic differentiation in vitro. Quercetin effectively protected the osteogenic differentiation of human periodontal ligament cells (hPDLCs) and periodontal tissue by upregulating the expression of Beclin-1 thus to promote autophagy and reduce oxidative stress damage. CONCLUSION: Our results established a role of oxidative stress damage and autophagy dysfunction in the mechanism of CSE-induced destruction of periodontal tissue and hPDLCs, and provided a potential application value of quercetin to ameliorate CSRP.

Electroacupuncture regulates macrophage, neutrophil, and oral microbiota to alleviate alveolar bone loss and inflammation in experimental ligature-induced periodontitis.

AIM: Electroacupuncture (EA) regulates distant body physiology through somatic sensory autonomic reflexes, balances the microbiome, and can promote the release of immune cells into bloodstream, thereby inhibiting severe systemic inflammation. This makes it possible to use EA as an integrated treatment for periodontitis. MATERIALS AND METHODS: In this study, EA was applied to the ST36 acupoints in a ligature-induced periodontitis (LIP) mouse model. Then the effects of EA on periodontal myeloid cells, cytokines, and the microbiome were comprehensively analysed using flow cytometry, quantitative Polymerase Chain Reaction (PCR), and 16 S sequencing. RESULTS: Results demonstrated that EA could significantly relieve periodontal bone resorption. EA also suppressed the infiltration of macrophages and neutrophils, reduced gene expression of the pro-inflammatory cytokines IL-1ß, IL-6, IL-17 and TNF-α, and increased expression of the anti-inflammatory factors IL-4 and IL-10 in periodontal tissues. Moreover, composition of the periodontal microbiome was regulated by EA, finding that complex of microbiota, including supragingival Veillonella, subgingival Streptococcus, and subgingival Erysipelatoclostridium, were significantly reduced. Meanwhile, nitrate and nitrate-related activities of subgingival microbiota were reversed. Network analysis revealed close relationships among Veillonella, Streptococcus, and Bacteroides. CONCLUSIONS: Our study indicates that EA can effectively alleviate inflammation and bone resorption in LIP mice, potentially via the regulation of myeloid cells, cytokines, and periodontal microbiome.

Multi-dimensional evaluation of cardiotoxicity in mice following respiratory exposure to polystyrene nanoplastics.

BACKGROUND: Nanoplastics (NPs) could be released into environment through the degradation of plastic products, and their content in the air cannot be ignored. To date, no studies have focused on the cardiac injury effects and underlying mechanisms induced by respiratory exposure to NPs. RESULTS: Here, we systematically investigated the cardiotoxicity of 40 nm polystyrene nanoplastics (PS-NPs) in mice exposed via inhalation. Four exposure concentrations (0 µg/day, 16 µg/day, 40 µg/day and 100 µg/day) and three exposure durations (1 week, 4 weeks, 12 weeks) were set for more comprehensive information and RNA-seq was performed to reveal the potential mechanisms of cardiotoxicity after acute, subacute and subchronic exposure. PS-NPs induced cardiac injury in a dose-dependent and time-dependent manner. Acute, subacute and subchronic exposure increased the levels of injury biomarkers and inflammation and disturbed the equilibrium between oxidase and antioxidase activity. Subacute and subchronic exposure dampened the cardiac systolic function and contributed to structural and ultrastructural damage in heart. Mechanistically, violent inflammatory and immune responses were evoked after acute exposure. Moreover, disturbed energy metabolism, especially the TCA cycle, in the myocardium caused by mitochondria damage may be the latent mechanism of PS-NPs-induced cardiac injury after subacute and subchronic exposure. CONCLUSION: The present study evaluated the cardiotoxicity induced by respiratory exposure to PS-NPs from multiple dimensions, including the accumulation of PS-NPs, cardiac functional assessment, histology observation, biomarkers detection and transcriptomic study. PS-NPs resulted in cardiac injury structurally and functionally in a dose-dependent and time-dependent manner, and mitochondria damage of myocardium induced by PS-NPs may be the potential mechanism for its cardiotoxicity.

Recent consequences of micro-nanaoplastics (MNPLs) in subcellular/molecular environmental pollution toxicity on human and animals.

Microplastics and Nanoplastics (MNPLs) pollution has been recognized as the important environmental pollution caused by human activities in addition to global warming, ozone layer depletion and ocean acidification. Most of the current studies have focused on the toxic effects caused by plastics and have not actively investigated the mechanisms causing cell death, especially at the subcellular level. The main content of this paper focuses on two aspects, one is a review of the current status of MNPLs contamination and recent advances in toxicological studies, which highlights the possible concentration levels of MNPLs in the environment and the internal exposure of humans. It is also proposed to pay attention to the compound toxicity of MNPLs as carriers of other environmental pollutants and pathogenic factors. Secondly, subcellular toxicity is discussed and the modes of entry and intracellular distribution of smaller-size MNPLs are analyzed, with particular emphasis on the importance of organelle damage to elucidate the mechanism of toxicity. Importantly, MNPLs are a new type of environmental pollutant and researchers need to focus not only on their toxicity, but also work with governments to develop measures to reduce plastic emissions, optimize degradation and control plastic aggression against organisms, especially humans, from multiple perspectives.

GSH-Activatable Aggregation-Induced Emission Cationic Lipid for Efficient Gene Delivery.

The key to gene therapy is the design of biocompatible and efficient delivery systems. In this work, a glutathione (GSH)-activated aggregation-induced-emission (AIE) cationic amphiphilic lipid, termed QM-SS-KK, was prepared for nonviral gene delivery. QM-SS-KK was composed of a hydrophilic biocompatible lysine tripeptide headgroup, a GSH-triggered disulfide linkage, and a hydrophobic AIE fluorophore QM-OH (QM: quinoline-malononitrile) tail. The peptide moiety could not only efficiently compact DNA but also well modulate the dispersion properties of QM-SS-KK, leading to the fluorescence-off state before GSH treatment. The cleavage of disulfide in QM-SS-KK by GSH generated AIE signals in situ with a tracking ability. The liposomes consisted of QM-SS-KK, and 1,2-dioleoylphosphatidylethanolamine (DOPE) (QM-SS-KK/DOPE) delivered plasmid DNAs (pDNAs) into cells with high efficiency. In particular, QM-SS-KK/DOPE had an enhanced transfection efficiency (TE) in the presence of 10% serum, which was two times higher than that of the commercial transfection agent PEI25K. These results highlighted the great potential of peptide and QM-based fluorescence AIE lipids for gene delivery applications.

Predicting the risk of dental implant loss using deep learning.

AIM: To investigate the feasibility of predicting dental implant loss risk with deep learning (DL) based on preoperative cone-beam computed tomography. MATERIALS AND METHODS: Six hundred and three patients who underwent implant surgery (279 high-risk patients who did and 324 low-risk patients who did not experience implant loss within 5 years) between January 2012 and January 2020 were enrolled. Three models, a logistic regression clinical model (CM) based on clinical features, a DL model based on radiography features, and an integrated model (IM) developed by combining CM with DL, were developed to predict the 5-year implant loss risk. The area under the receiver operating characteristic curve (AUC) was used to evaluate the model performance. Time to implant loss was considered for both groups, and Kaplan-Meier curves were created and compared by the log-rank test. RESULTS: The IM exhibited the best performance in predicting implant loss risk (AUC = 0.90, 95% confidence interval [CI] 0.84-0.95), followed by the DL model (AUC = 0.87, 95% CI 0.80-0.92) and the CM (AUC = 0.72, 95% CI 0.63-0.79). CONCLUSIONS: Our study offers preliminary evidence that both the DL model and the IM performed well in predicting implant fate within 5 years and thus may greatly facilitate implant practitioners in assessing preoperative risks.

[Effects of Three Illuminants on the Color of High Translucent Multilayered Zirconia].

OBJECTIVE: To evaluate the effects of three common illuminants on the color of four brands of high translucent multilayered zirconia (HTMZ) ceramics so as to provide reference for clinical practice and dental restoration fabrication, and to reduce the risks for illuminant change causing color mismatch between the natural teeth and the restorations made of HTMZ. METHODS: Four brands of commonly used HTMZ were selected and ten cuboid samples ( n=10/group) of 12 mm×10 mm×0.8 mm were prepared for each type of HTMZ. The L*, a*, and b* values of the samples were measured under D65, A and F2, three standard illuminants. Then, the L*, a*, and b* values were statistically analyzed by using factors of the type of the illuminant and the brand of the zirconia. Color difference (ΔE) of samples of the same brand under exposure to changed illuminants was also calculated. RESULTS: When the same samples were exposure to different illuminants, there was no significant difference in the L* value, the a* value for the different iluminants was shown to be illuminant A>illuminant F2>illuminant D65, and the b* value was shown to be illuminant F2>illuminant D65>illuminant A. The L*, a*, and b* values of samples of different brands showed statistically significant difference when they were exposed to the same illuminant ( P<0.0001). Samples of the same brand showed ΔE when they were under the three different illuninants, and all ΔE were clinically acceptable. CONCLUSION: The types of illuminant used, to a certain degree, affected the hue and chroma of HTMZ. There were colorimetric differences between restorations made of different brands of HTMZ ceramics of the same color. The types of illuminants most common to the daily life of patients and the color characteristics of materials of different brands should be taken into consideration to facilitate the selection of restoration materials and dental restoration fabrication, and to reduce the risks for color mismatch between the restorations and the adjacent teeth caused by the change of illuminants.

A Polymeric Nanobeacon for Monitoring the Fluctuation of Hydrogen Polysulfides during Fertilization and Embryonic Development.

Fertilization and early embryonic development as the beginning of a new life are key biological events. Hydrogen polysulfide (H2 Sn ) plays important roles during physiological regulation, such as antioxidation-protection. However, no report has studied in situ H2 Sn fluctuation during early embryonic development because of the low abundance of H2 Sn and inadequate sensitivity of probes. We herein construct a polymeric nanobeacon from a H2 Sn -responsive polymer and fluorophores, which is capable of detecting H2 Sn selectively and of signal amplification. Taking the zebrafish as a model, the polymeric nanobeacon revealed that the H2 Sn level was significantly elevated after fertilization due to the activation of cell multiplication, suppressed partially during embryonic development, and finally kept steady up to zebrafish emergence. This strategy is generally accessible for biomarkers by altering the responsive unit and significant for facilitating biological analysis during life development.

Self-Immolative Dye-Doped Polymeric Probe for Precisely Imaging Hydroxyl Radicals by Avoiding Leakage.

For sensing low abundance of biomarkers, utilizing nanocarriers to load dyes is an efficient method to amplify the detected signal. However, the non-specific leak of the internal dyes in this approach is accompanied by false positive signals, resulting in inaccurate signal acquirement. To address this issue, in this work, we reported a novel signal amplification strategy with dye as a scaffold to construct a self-immolative dye-doped polymeric probe (SDPP). In our proposed approach, the dyes were covalently integrated into the main chain of a polymer, which can avoid the non-specific leak of the dye when used in a rigorous biological environment, thus evading the false positive signal. As a prototype of this concept, a SDPP, which responds to hydroxyl radicals (•OH), was rationally fabricated. Upon being activated by •OH, SDPP will liberate the dye through a self-immolative reaction to bind with protein for amplifying the fluorescence signal. Compared with a dye-loaded nanoprobe, SDPP can precisely track intracellular basal •OH levels and visualize the •OH associated with myocarditis in vivo. More importantly, the attempt in this work not only provides an effective molecular tool to investigate the role of •OH in cardiopathy, but also puts forward a new direction to current signal-amplifying strategies for precisely and reliably acquiring the intracellular molecular information.

Nanotube-decorated hierarchical tantalum scaffold promoted early osseointegration.

This study aimed to fabricate a hierarchical tantalum scaffold mimicking natural bone structure to enhance osseointegration. Porous tantalum scaffolds (p-Ta) with microgradients were fabricated by selective laser melting according to a computer-aided design model. Electrochemical anodization produced nanotubes on the p-Ta surface (p-Ta-nt). SEM verified the construction of a unique nanostructure on p-Ta-nt. Contact angle and protein adsorption measurements demonstrated that p-Ta-nt have enhanced hydrophilicity and protein absorption. MC3T3-E1 preosteoblasts showed increased filamentous pseudopods and comparable cell proliferation when cultured on p-Ta-nt. Osteogenic marker gene (Osterix, Runx2, COL-I) transcription was significantly upregulated in MC3T3-E1 cells cultured on p-Ta-nt after 7 days. After implantation into the femurs of New Zealand white rabbits for 2 weeks, histological examination found improved early osseointegration in the p-Ta-nt group. This study showed that a hierarchical tantalum structure could enhance early osteogenic effects in vitro and in vivo.

In vitro evaluation of nanoplastics using human lung epithelial cells, microarray analysis and co-culture model.

Nanoplastics, including polystyrene nanoplastics (PS-NPs), are widely existed in the atmosphere, which can be directly and continuously inhaled into the human body, posing a serious threat to the respiratory system. Therefore, it is urgent to estimate the potential pulmonary toxicity of airborne NPs and understand its underlying mechanism. In this research, we used two types of human lung epithelial cells (bronchial epithelium transformed with Ad12-SV40 2B, BEAS-2B) and (human pulmonary alveolar epithelial cells, HPAEpiC) to investigate the association between lung injury and PS-NPs. We found PS-NPs could significantly reduce cell viability in a dose-dependent manner and selected 7.5, 15 and 30 µg/cm2 PS-NPs as the exposure dosage levels. Microarray detection revealed that 770 genes in the 7.5 µg/cm2 group and 1951 genes in the 30 µg/cm2 group were distinctly altered compared to the control group. Function analysis suggested that redox imbalance might play central roles in PS-NPs induced lung injury. Further experiments verified that PS-NPs could break redox equilibrium, induce inflammatory effects, and triggered apoptotic pathways to cause cell death. Importantly, we found that PS-NPs could decrease transepithelial electrical resistance by depleting tight junctional proteins. Result also demonstrated that PS-NPs-treated cells increased matrix metallopeptidase 9 and Surfactant protein A levels, suggesting the exposure of PS-NPs might reduce the repair ability of the lung and cause tissue damage. In conclusion, nanoplastics could induce oxidative stress and inflammatory responses, followed by cell death and epithelial barrier destruction, which might result in tissue damage and lung disease after prolonged exposure.

Ropeginterferon Alfa-2b administered every two weeks for patients with genotype 2 chronic hepatitis C.

BACKGROUND: Ropeginterferon alfa-2b is a novel mono-pegylated interferon that has only one major form as opposed to the 8 to 14 isomers of other on-market pegylated interferon products, allowing every-two-week injection with high tolerability. It received European Medicines Agency marketing authorization in 2019 and Taiwan Biologics License Applications Approval in 2020 for the treatment of polycythemia vera. This study aimed to evaluate the safety and efficacy of Ropeginterferon alfa-2b plus ribavirin in genotype 2 chronic hepatitis C (CHC) patients. METHODS: Eighty-six treatment naive patients with genotype 2 CHC were randomized to weekly peginterferon alfa-2a (Peg-IFN-α2a) at 180 µg (n = 22), or every-two-week Ropeginterferon alfa-2b at 270 µg (n = 23), 360 µg (n = 21), 450 µg (n = 20), plus daily oral ribavirin 1000 mg (≤75 kg) or 1200 mg (>75 kg). Patients with rapid virologic response received 16-week regimen while those without RVR received 24-week regimen. The primary endpoint was sustained virologic response at 24 weeks post-treatment (SVR24). RESULTS: SVR24 was achieved by 95.5%, 78.3%, 85.7%, and 60% of subjects in Peg-IFN-α2a 180 µg, Ropeginterferon alfa-2b 270 µg, 360 µg, and 450 µg groups, respectively. The safety profile was similar across 4 groups. The incidence rate of adverse event during the treatment period was 0.407, 0.252, 0.395, and 0.347 per patient-week, respectively. CONCLUSION: Ropeginterferon alfa-2b, although at only half the number of injections, is as safe and effective as Peg-IFN-α2a for genotype 2 CHC. A phase 3 study to confirm safety and efficacy of Ropeginterferon alfa-2b in genotype 2 CHC is ongoing.

Enhancing effect of macroporous adsorption resin on gamma-aminobutyric acid production by Enterococcus faecium in whole-cell biotransformation system.

Gamma-aminobutyric acid (GABA) biosynthesis depended to a great extent on the biotransformation characterization of glutamate decarboxylase (GAD) and process conditions. In this paper, the enhancing effect of D101 macroporous adsorption resin (MAR) on the GABA production was investigated based on the whole-cell biotransformation characterization of Enterococcus faecium and adsorption characteristics of D101 MAR. The results indicated that the optimal pH for reaction activity of whole-cell GAD and pure GAD was 4.4 and 5.0, respectively, and the pH range retained at least 50% of GAD activity was from 4.8 to 5.6 and 4.0-4.8, respectively. No substrate inhibition effect was observed on both pure GAD and whole-cell GAD, and the maximum activity could be obtained when the initial L-glutamic acid (L-Glu) concentration exceeded 57.6 mmol/L and 96.0 mmol/L, respectively. Besides, GABA could significantly inhibit the activity of whole-cell GAD rather than pure GAD. When the initial GABA concentration of the reaction solution remained 100 mmol/L, 33.51 ± 9.11% of the whole-cell GAD activity was inhibited. D101 MAR exhibited excellent properties in stabilizing the pH of the conversion reaction system, supplementing free L-Glu and removing excess GABA. Comparison of the biotransformation only in acetate buffer, the GABA production, with 50 g/100 mL of D101 MAR, was significantly increased by 138.71 ± 5.73%. D101 MAR with pre-adsorbed L-Glu could significantly enhance the production of GABA by gradual replenishment of free L-Glu, removing GABA and maintaining the pH of the reaction system, which would eventually make the GABA production more economical and eco-friendly.

Optimization of n-butanol synthesis in Lactobacillus brevis via the functional expression of thl, hbd, crt and ter.

N-butanol is an important chemical and can be naturally synthesized by Clostridium species; however, the poor n-butanol tolerance of Clostridium impedes the further improvement in titer. In this study, Lactobacillus brevis, which possesses a higher butanol tolerance, was selected as host for heterologous butanol production. The Clostridium acetobutylicum genes thl, hbd, and crt which encode thiolase, ß-hydroxybutyryl-CoA dehydrogenase, and crotonase, and the Treponema denticola gene ter, which encodes trans-enoyl-CoA reductase were cloned into a single plasmid to express the butanol synthesis pathway in L. brevis. A titer of 40 mg/L n-butanol was initially achieved with plasmid pLY15-opt, in which all pathway genes are codon-optimized. A titer of 450 mg/L of n-butanol was then synthesized when ter was further overexpressed in this pathway. The role of metabolic flux was reinforced with pLY15, in which only the ter gene was codon-optimized, which greatly increased the n-butanol titer to 817 mg/L. Our strategy significantly improved n-butanol synthesis in L. brevis and the final titer is the highest achieved amongst butanol-tolerant lactic acid bacteria.

Electrochemically Exfoliated High-Quality 2H-MoS2 for Multiflake Thin Film Flexible Biosensors.

2D molybdenum disulfide (MoS2 ) gives a new inspiration for the field of nanoelectronics, photovoltaics, and sensorics. However, the most common processing technology, e.g., liquid-phase based scalable exfoliation used for device fabrication, leads to the number of shortcomings that impede their large area production and integration. Major challenges are associated with the small size and low concentration of MoS2 flakes, as well as insufficient control over their physical properties, e.g., internal heterogeneity of the metallic and semiconducting phases. Here it is demonstrated that large semiconducting MoS2 sheets (with dimensions up to 50 µm) can be obtained by a facile cathodic exfoliation approach in nonaqueous electrolyte. The synthetic process avoids surface oxidation thus preserving the MoS2 sheets with intact crystalline structure. It is further demonstrated at the proof-of-concept level, a solution-processed large area (60 × 60 µm) flexible Ebola biosensor, based on a MoS2 thin film (6 µm thickness) fabricated via restacking of the multiple flakes on the polyimide substrate. The experimental results reveal a low detection limit (in femtomolar-picomolar range) of the fabricated sensor devices. The presented exfoliation method opens up new opportunities for fabrication of large arrays of multifunctional biomedical devices based on novel 2D materials.

Improved n-Butanol Production from Clostridium cellulovorans by Integrated Metabolic and Evolutionary Engineering.

Clostridium cellulovorans DSM 743B offers potential as a chassis strain for biomass refining by consolidated bioprocessing (CBP). However, its n-butanol production from lignocellulosic biomass has yet to be demonstrated. This study demonstrates the construction of a coenzyme A (CoA)-dependent acetone-butanol-ethanol (ABE) pathway in C. cellulovorans by introducing adhE1 and ctfA-ctfB-adc genes from Clostridium acetobutylicum ATCC 824, which enabled it to produce n-butanol using the abundant and low-cost agricultural waste of alkali-extracted, deshelled corn cobs (AECC) as the sole carbon source. Then, a novel adaptive laboratory evolution (ALE) approach was adapted to strengthen the n-butanol tolerance of C. cellulovorans to fully utilize its n-butanol output potential. To further improve n-butanol production, both metabolic engineering and evolutionary engineering were combined, using the evolved strain as a host for metabolic engineering. The n-butanol production from AECC of the engineered C. cellulovorans was increased 138-fold, from less than 0.025 g/liter to 3.47 g/liter. This method represents a milestone toward n-butanol production by CBP, using a single recombinant clostridium strain. The engineered strain offers a promising CBP-enabling microbial chassis for n-butanol fermentation from lignocellulose.IMPORTANCE Due to a lack of genetic tools, Clostridium cellulovorans DSM 743B has not been comprehensively explored as a putative strain platform for n-butanol production by consolidated bioprocessing (CBP). Based on the previous study of genetic tools, strain engineering of C. cellulovorans for the development of a CBP-enabling microbial chassis was demonstrated in this study. Metabolic engineering and evolutionary engineering were integrated to improve the n-butanol production of C. cellulovorans from the low-cost renewable agricultural waste of alkali-extracted, deshelled corn cobs (AECC). The n-butanol production from AECC was increased 138-fold, from less than 0.025 g/liter to 3.47 g/liter, which represents the highest titer of n-butanol produced using a single recombinant clostridium strain by CBP reported to date. This engineered strain serves as a promising chassis for n-butanol production from lignocellulose by CBP.

Adsorptive decontamination of Cu2+-contaminated water and soil by carboxylated graphene oxide/chitosan/cellulose composite beads.

Graphene adsorbents have been applied to remove diverse pollutants from aqueous systems. However, the mechanical strength of most graphene adsorbents is low and the fragile graphene sheets are released into the environment. In this study, we prepared carboxylated graphene oxide/chitosan/cellulose (GCCSC) composite beads with good mechanical strength for the immobilization of Cu2+ from both water and soil. The proportional limit of GCCSC beads was 3.2 N, a much larger value than graphene oxide beads (0.2 N). The largest pressure for GCCSC beads recorded before brittle failure was 26 N. The Cu2+ adsorption capacity of GCCSC beads was 22.4 mg/g in aqueous systems at initial Cu2+ concentration of 40 µg/mL, which is competitive with many efficient adsorbents. The partition coefficient (PC) for the Cu2+ adsorption onto GCCSC beads was 1.12 mg/g/µM at Ce of 0.83 mg/L and qe of 14.3 mg/g. The PC decreased to 0.055 mg/g/µM at Ce of 26.0 mg/L and qe of 22.4 mg/g. The adsorption kinetics of Cu2+ on GCCSC beads were moderately fast and required approximately 3 h to reach equilibrium with a k2 of 0.0021 g/(mg·min). A lower temperature and higher pH slightly increased the adsorption capacity of GCCSC beads. The ionic strength did not influence the adsorption. The porous structure of GCCSC beads blocked the direct contact between soil and the graphene surface; thus, a high Cu2+ immobilization efficiency was achieved by GCCSC beads applied to soil. The implications for the design of high-performance graphene adsorbents for water and soil remediation are discussed.

Nd-induced honeycomb structure of intermetallic phase enhances the corrosion resistance of Mg alloys for bone implants.

Mg-5.6Zn-0.5Zr alloy (ZK60) tends to degrade too rapid for orthopedic application, in spite of its natural degradation, suitable strength and good biocompatibility. In this study, Nd was alloyed with ZK60 via laser melting method to enhance its corrosion resistance. The microstructure features, mechanical properties and corrosion behaviors of ZK60-xNd (x = 0, 1.8, 3.6, 5.4 wt.%) were investigated. Results showed that laser melted ZK60-xNd were composed of fine ɑ-Mg grains and intermetallic phases along grain boundaries. And the precipitated intermetallic phases experienced successive changes: divorced island-like MgZn phase → honeycomb-like T phase → coarsened and agglomerated W phase with Nd increasing. It was worth noting that ZK60-3.6Nd with honeycomb-like T phase exhibited an optimal corrosion behavior with a corrosion rate of 1.56 mm year-1. The improved corrosion behavior was ascribed to: (I) dense surface film caused by the formation of Nd2O3 hindered the invasion of immersion solution; (II) the three-dimensional honeycomb structure of intermetallic phases formed a tight barrier to restrain the propagation of corrosion. Moreover, ZK60-3.6Nd exhibited good biocompatibility. It was suggested that ZK60-3.6Nd was a preferable candidate for biodegradable bone implant.