A Chemiluminescence Sensor for the Detection of α-Fetoprotein and Carcinoembryonic Antigen Based on Dual-Aptamer Functionalized Magnetic Silicon Composite.

In this work, a dual-aptamer functionalized magnetic silicon composite was prepared and used to construct a chemiluminescence (CL) sensor for the detection of α-fetoprotein (AFP) and carcinoembryonic antigen (CEA). First, SiO2@Fe3O4 was prepared, and polydiallyl dimethylammonium chloride (PDDA) and AuNPs were sequentially loaded on SiO2@Fe3O4. Subsequently, the complementary strand of CEA aptamer (cDNA2) and the aptamer of AFP (Apt1) were attached to AuNPs/PDDA-SiO2@Fe3O4. Then, the aptamer of CEA (Apt2) and G quadruplex peroxide-mimicking enzyme (G-DNAzyme) were sequentially connected to cDNA2, leading to the final composite. Then, the composite was used to construct a CL sensor. When AFP is present, it will combine with Apt1 on the composite to hinder the catalytic ability of AuNPs to luminol-H2O2, achieving AFP detection. When CEA is present, it will recognize and bind with Apt2, so G-DNAzyme is released to solution and catalyzes the reaction of luminol-H2O2 to achieve CEA determination. After the application of the prepared composite, AFP and CEA were detected in the magnetic medium and supernatant, respectively, after simple magnetic separation. Therefore, the detection of multiple liver cancer markers is realized through the CL technology without additional instruments or technology, which broadens the application range of CL technology. The sensor for detecting AFP and CEA shows wide linear ranges of 1.0 × 10-4 to 1.0 ng·mL-1 and 0.0001-0.5 ng·mL-1 and low detection limits of 6.7 × 10-5 ng·mL-1 and 3.2 × 10-5 ng·mL-1, respectively. Finally, the sensor was successfully used to detect CEA and AFP in serum samples and provides great potential for detection of multiple liver cancer markers in early clinical diagnosis.

Weak electrostimulation enhanced the microbial transformation of ibuprofen and naproxen.

Ibuprofen (IBU) and naproxen (NPX) are commonly used non-steroidal anti-inflammatory drugs (NSAIDs) with high-risk quotients and are frequently detected in various aquatic environments. A weak electrostimulated biofilm not only had improved removal efficiencies to IBU and NPX, but also transformed different enantiomers with comparable efficiency and without configuration inversion. IBU was transformed mainly by oxidation (hydroxyl-IBU, carboxy-IBU), while NPX was mainly detoxified. The microbial analysis of IBU and NPX biofilm showed that the shared core consortia (> 1%) contained typical electro-active bacteria (Geobacter, Desulfovibrio), fermenters (Petrimonas, Acetobacterium) and potential degraders (Pandoraea, Nocardiaceae), which exhibited synergistic interactions by exchanging the additional electrons, H+, coenzyme NAD(H) or NAD(P) (H) and energy. The fungal community has a significant correlation to those core bacteria and they may also play transformation roles with their diverse enzymes. Plenty of nonspecific oxidoreductase, decarboxylase, hydrolase, cytochrome P450, and other enzymes relating to xenobiotic degradation were high-abundance encoded by the core consortia and could potentially participate in IBU and NPX biotransformation. This study offers new insights into the functional microbes and enzymes working on complex NSAIDs biotransformation and provided a feasible strategy for the enhanced removal of NSAIDs (especially IBU and NPX).

Enhanced simultaneous partial nitrification and denitrification performance of aerobic granular sludge via tapered aeration in sequencing batch reactor for treating low strength and low COD/TN ratio municipal wastewater.

The aerobic granular sludge simultaneous partial nitrification, denitrification and phosphorus removal (AGS-SPNDPR) process was carried out via tapered aeration in sequencing batch reactor (SBR) for treating low strength and low COD/TN ratio municipal wastewater. The results showed that aerobic granular sludge was successfully cultivated with good sedimentation performance when treating the municipal wastewater. Meanwhile, the median granule size increased to 270 (R1) and 257 (R2) µm on day 80. The excellent removal performance of COD (92%) and NH4+-N (95%) were achieved under different aeration modes, while the higher TN removal efficiency (76%) was achieved by tapered aeration. The accumulation of NO2--N in R2 indicated that the tapered aeration was beneficial to achieve simultaneously partial nitrification and denitrification. Meanwhile, the high-efficiency phosphorus (95%) removal was realized via additional carbon source, and SPNDPR process was formed under tapered aeration. The bacterial community analysis indicated denitrifying glycogen-accumulating organisms (DGAOs) Candidatus_Competibacter and ammonia-oxidizing bacteria (AOB) Nitrosomonas were more effectively enriched via tapered aeration, while phosphorus-accumulating organisms (PAOs) Candidatus_Accumulibacter were effectively enriched under additional organic carbon. AOB, denitrifying bacteria and PAOs were simultaneously enriched by tapered aeration and additional carbon source, which was beneficial to nutrients removal. This study might be conducive to the application of AGS-SPNDPR system for treating low strength and low COD/TN ratio municipal wastewater under tapered aeration.

Multifaceted synergistic electron transfer mechanism for enhancing denitrification by clay minerals.

The performance and mechanism of denitrification enhanced by three clay minerals, montmorillonite (Mmt), illite and kaolinite, were first studied. Batch experiments indicated that clay minerals significantly enhanced denitrification at certain concentrations (0.1-1 g/L). The denitrification rate with 1 g/L Mmt was increased by 5.0-fold. The mechanism of clay minerals promoting denitrification was analyzed from three aspects: electron transfer characteristics, interfacial interaction and metabolism activity. Electrochemical tests showed that the clay minerals promoted electron transfer rate by improving current efficiency and electronic accommodation capacity. The biofilm formation on the clay minerals interface indicated that micro-domain catalytic phases were formed, which was beneficial to improve the nitrate reduction rate. In addition, nicotinamide adenine dinucleotide, nitrate reductase and nitrite reductase activities in Mmt-supplemented system were increased by 283.3%, 128.1% and 126.2%, respectively; and extracellular polymeric substance secretion was enhanced, indicating that the addition of clay minerals promoted microbial metabolic activity. Higher microbial diversity and enrichment of electroactive bacteria were observed in the Mmt-supplemented system. Based on the above exploration, the multifaceted synergistic mechanism was proposed to account for the enhanced denitrification performance on clay minerals. Overall, this study expanded understanding of the roles of clay minerals on denitrification and provided strategies for accelerating the biological transformation process.

Emodin ameliorates antioxidant capacity and exerts neuroprotective effect via PKM2-mediated Nrf2 transactivation.

Pyruvate kinase M2 (PKM2) is overexpressed in neuronal cells. However, there are few studies on the involvement of PKM2 modulators in neurodegenerative diseases. Emodin, a dominating anthraquinone derivative extracting from the rhizome of rhubarb, has received expanding consideration due to its pharmacological properties. Our data reveal that emodin could resist hydrogen peroxide- or 6-hydroxydopamine-mediated mitochondrial fission and apoptosis in PC12 cells (a neuron-like rat pheochromocytoma cell line). Notably, emodin at nontoxic concentrations significantly inhibits PKM2 activity and promotes dissociation of tetrameric PKM2 into dimers in cells. The PKM2 dimerization enhances the interaction of PKM2 and NFE2-related factor 2 (Nrf2), which further triggers the activation of the Nrf2/ARE pathway to upregulate a panel of cytoprotective genes. Modulating the PKM2/Nrf2/ARE axis by emodin unveils a novel mechanism for understanding the pharmacological functions of emodin. Our findings indicate that emodin is a potential candidate for the treatment of oxidative stress-related neurodegenerative disorders.

Oat polyphenol avenanthramide-2c confers protection from oxidative stress by regulating the Nrf2-ARE signaling pathway in PC12 cells.

Accumulating evidence has demonstrated that cellular antioxidant systems play essential roles in retarding oxidative stress-related diseases, such as Parkinson's disease. Because nuclear factor erythroid 2-related factor 2 (Nrf2) is a chief regulator of cellular antioxidant systems, small molecules with Nrf2-activating ability may be promising neuroprotective agents. Avenanthramide-2c (Aven-2c), avenanthramide-2f (Aven-2f) and avenanthramide-2p (Aven-2p) are the most abundant avenanthramides in oats, and they have been documented to possess multiple pharmacological benefits. In this work, we synthesized these three compounds and evaluated their cytoprotective effect against oxidative stress-induced PC12 cell injuries. Aven-2c displayed the best protective potency among them. Aven-2c conferred protection on PC12 cells by scavenging free radicals and activating the Nrf2-ARE signaling pathway. Pretreatment of PC12 cells with Aven-2c efficiently enhanced Nrf2 nuclear accumulation and evoked the expression of a set of cytoprotective molecules. The mechanistic study also supports that Nrf2 activation is the molecular basis for the cellular action of Aven-2c. Collectively, this study demonstrates that Aven-2c is a potent Nrf2 agonist, shedding light on the potential usage of Aven-2c in the treatment of neuroprotective diseases.

Effect of calcinated pyrite on simultaneous ammonia, nitrate and phosphorus removal in the BAF system and the Fe2+ regulatory mechanisms: Electron transfer and biofilm properties.

To efficiently remove nitrogen and phosphorus from secondary effluent with low values of COD/TN, a novel biological aerated filter (BAF) utilizing calcined pyrite with a large specific surface area (SSA) and pore diameter (PD) was designed to address this challenge. From the perspective of nutrients removal performance, and the corresponding effluent total nitrogen (TN) and PO43--P in the calcined pyrite autotrophic denitrification (CPAD) process decreased from 40.21 to 1.07 mg/L to 1.22 and 0.14 mg/L, respectively. Furthermore, the nutrients removal kinetics analysis showed that the CPAD and pyrite autotrophic denitrification (PAD) processes could be fitted with Half-order and Zero-order reactions via kinetics analysis, respectively, indicating that the TN removal performance of CPAD processes was better than that of the PAD process. Moreover, CPAD combined with sulfur autotrophic denitrification (SAD) processes was fitted by First-order reaction, and the TN removal performance was further enhanced over the CPAD process. From the perspective of microregulation, Fe2+ production in the PAD and CPAD processes could accelerate the electron transfer rate by increasing electron transport system activity (ETSA) and reducing electrochemical impedance spectroscopy (EIS). Moreover, Fe2+ stimulated microbes to produce more proteins (PN) and C10-HSL, which improved biofilm stability and interspecific communication processes. Notably, nitrifiers and autotrophic denitrifiers were simultaneously enriched via detection of high-throughput sequencing of 16 S rRNA genes, which verified the feasibility of simultaneous nitrification and autotrophic denitrification. Therefore, BAF with calcined pyrite and sulfur as composite fillers have a considerable advantage in nutrients removal.

Effect of dissolved oxygen on simultaneous removal of ammonia, nitrate and phosphorus via biological aerated filter with sulfur and pyrite as composite fillers.

A biological aerated filter (BAF) with sulfur and pyrite as fillers were structured to simultaneously remove NH4+-N, NO3--N and PO43--P from secondary effluent. When dissolved oxygen (DO) was 1.2-1.5 mg/L, effluent concentration of NH4+-N, NO3--N and PO43--P were below 0.65, 0.47 and 0.18 mg/L, respectively. Meanwhile, Fe2+ production via decomposing pyrite could improve autotrophic denitrification performance. Besides, sulfur and pyrite autotrophic denitrification process (PAD and SAD) aligned with the Zero-order and First-order kinetics models, respectively, indicating that the sulfur had excellent capability of providing electron. Moreover, there was a positive correlation between the nitrogen removal performance and protein-like substances in extracellular polymeric substances. Bacterial community analysis suggested the nitrifiers and autotrophic denitrifiers were simultaneously enriched. Principal component analysis indicated that the DO concentration and type of electron donors impacted bacterial community. Consequently, BAF combined with PAD and SAD processes provides an alternative method to remove nutrients.

Enhanced denitrification performance and biocatalysis mechanisms of polyoxometalates as environmentally-friendly inorganic redox mediators.

Polyoxometalates (POMs) used in chemical catalysis field were first explored their effect on the denitrification process. Experiments demonstrated that NO3--N reduction rate with 0.05 mM phosphomolybdic acid (PMo12) was approximately 3.93-fold higher than the PMo12-free system. Simultaneously, PMo12 also had positive effect on NO2--N reduction. Compared with the PMo12-free system, the solution resistance and oxidation-reduction potential were decreased, and the activation energy (Ea) was reduced by 51.84 kJ/mol. Besides, electron conductive substances in extracellular polymeric substances were stimulated by PMo12. NADH and riboflavin were enhanced to increase denitrification electron transport system activity. Higher microbial diversity and enrichment of Salmonella were observed in the PMo12-supplemented system. Based on the above analysis, the catalyzing mechanisms of PMo12 are proposed that PMo12 made it easier for electron transferring from electron donor to electron acceptor and shifted bacterial community structure. These findings may provide a promising strategy for nitrogen wastewater treatment.

Activation of Nrf2-driven antioxidant enzymes by cardamonin confers neuroprotection of PC12 cells against oxidative damage.

Oxidative stress represents a disorder of the redox equilibrium between the production of free radicals and the capability of cells to eliminate them. As subversion of this redox balance is thought to initiate various diseases, living cells maintain a redox equilibrium diligently. More and more pieces of evidence show that oxidative stress has already become a common risk factor in the pathogenesis of neurodegenerative disorders. So, considerable importance has been given to the prevention of oxidative stress as a potential therapeutic strategy. It is well known that the Nrf2-ARE pathway represents one of the most important cellular endogenous defense mechanisms against oxidative stress. Activation of Nrf2 signaling induces the transcriptional regulation of multiple ARE-dependent antioxidant defense genes. Here, we showed that cardamonin (CD), a chalcone isolated from Alpinia katsumadai, attenuated cell death induced by hydrogen peroxide (H2O2) and 6-hydroxydopamine (6-OHDA) in PC12 cells. Pretreatment of PC12 cells with CD dose-dependently upregulated the expression of phase II antioxidant molecules governed by Nrf2. In contrast, CD failed to provide neuroprotection after silencing Nrf2 expression, indicating that this cytoprotection may be mediated by the activation of transcription factor Nrf2. Our results demonstrate that CD is a novel small molecule activator of Nrf2 in PC12 cells, and suggest that CD may be a potential candidate for the prevention of oxidative stress-mediated neurodegenerative disorders.

Synthesis, crystal structure, photoluminescence property and photoelectronic behavior of two uranyl-organic frameworks constructed from 1, 2, 4, 5-benzenetetracarboxylic acid as ligand.

By using 1, 2, 4, 5-benzenetetracarboxylic acid as organic ligands, two uranyl coordination complexes, (UO2)2(bta)(DMA)2 (1) and [(UO2)2(bta)(µ3-OH2)]·2[HN(CH3)2]·H2O (2) (H4bta=1, 2, 4, 5-benzenetetracarboxylic acid, DMA=N,N-Dimethylacetamide) were synthesized. The X-ray single crystal analysis revealed that complex 1 exhibits a 3-demensional framework, while complex 2 exhibits a 2-demensional framework. In order to furthermore characterize the two complexes and extend their functional properties, spectroscopies of IR, UV-vis, photoluminescence and surface photovoltage were also studied primarily. In addition, thermogravimetric analyses and photocatalytic studies for complexes 1 and 2 were discussed in detail.

A20 overexpression under control of mouse osteocalcin promoter in MC3T3-E1 cells inhibited tumor necrosis factor-alpha-induced apoptosis.

AIM: To construct an A20 expression vector under the control of mouse osteocalcin promoter (OC-A20), and investigate osteoblastic MC3T3-E1 cell line, which stably overexpresses A20 protein prevented tumor necrosis factor (TNF)-alpha-induced apoptosis. METHODS: OC-A20 vector was constructed by fusing a fragment of the mouse osteocalcin gene-2 promoter with human A20 complementary DNA. Then the mouse MC3T3-E1 cell line, stably transfected by A20, was established. The expression of A20 mRNA and A20 protein in the cells were detected by reverse transcription-polymerase chain reaction (RT-PCR) and Western blot analysis, respectively. To determine the specificity of A20 expression in osteoblast, the mouse osteoblastic MC3T3-E1 cell line and mouse embryo fibroblast NIH3T3 cell line were transiently transfected with OC-A20. The anti-apoptotic role of A20 in MC3T3-E1 cells was determined by Flow cytometric analysis (FACS), terminal dUTP nick endo-labeling (TUNEL) and DNA gel electrophoresis analysis (DNA Ladder), respectively. RESULTS: Weak A20 expression was found in MC3T3-E1 cells with the primers of mouse A20. A20 mRNA and A20 protein expression were identified in MC3T3-E1 cells transfected with OC-A20 using RT-PCR and Western blot analysis. Only A20 mRNA expression was found in MC3T3-E1 cell after MC3T3-E1 cells and NIH3T3 cells were transient transfected with OC-A20. A decrease obviously occurred in the rate of apoptosis in the OC-A20 group compared with the empty vector (pcDNA3) group by FACS (P< 0.001). A significant increase in TUNEL positive staining was found in the pcDNA group compared with OC-A20 group (P< 0.001). Simultaneously, similar effects were demonstrated in DNA gel electrophoresis analysis. CONCLUSION: We constructed an osteoblast-specific expression vector that expressed A20 protein in MC3T3-E1 cells and confirmed that A20 protects osteoblast against TNF-alpha-induced apoptosis.