Dual "on-off" signal conversion strategy based on surface plasmon coupling and resonance energy transfer for visual electrochemiluminescence ratiometric analysis of MiRNA-141.

An electrochemiluminescence (ECL) biosensor with a pair of new ECL emitters and a novel sensing mechanism was designed for the high-sensitivity detection of microRNA-141 (miRNA-141). Sulfur-doped boron nitrogen quantum dots (S-BN QDs) were initially employed to modify the cathode of the bipolar electrode (BPE), while the anode reservoir was [Ir(dfppy)2(bpy)]PF6/TPrA system. The next step involved attaching H1-bound ultra-small WO3-x nanodots (WO3-x NDs) to the S-BN QDs-modified BPE cathode via DNA hybridization. A strong surface plasmon coupling (SPC) effect was observed between S-BN QDs and WO3-x NDs, which allowed for the enhancement of the red and visible ECL emission from S-BN QDs. After target-induced cyclic amplification to produce abundant Zn2+ and Au NPs-DNA3-Au NPs (Au NPs-S3-Au NPs), Zn2+ could cleave DNA at a nucleotide sequence-specific recognition site to release the WO3-x NDs, resulting in the first diminution of cathode ECL signal and the first enhancement of anode ECL signal. Moreover, the ECL signal at cathode decreased for the second time and the emission of [Ir(dfppy)2(bpy)]PF6 was continuously enhanced after the introduction of Au nanoparticles-S3-Au nanoparticles on the cathode surface. Our sensing mode with a dual "on-off" signal conversion strategy shows a good detection capability for miRNAs ranging from 10-17 to 10-10 M, with a limit of detection (LOD) as low as 10-17 M, which has great application potential in biomedical research and clinical diagnosis.

Ultrasensitive and Visual Electrochemiluminescence Ratiometry Based on a Constant Resistor-Integrated Bipolar Electrode for MicroRNA Detection.

In this work, a new electrochemiluminescence (ECL) platform was constructed for detecting the prostate cancer marker microRNA-141 (miRNA-141) on a constant resistor-integrated closed bipolar electrode (BPE). It consisted of two reservoirs and a constant resistor, and both ends were connected to the anode of the driving electrode and the cathode of BPE. The cathode of BPE was modified with boron nitride quantum dots (BNQDs), and the anode reservoir was the [Ru(bpy)3](PF6)2/TPrA system. After introducing a certain amount of hairpin DNA 3 (H3) and ferrocene-labeled single-stranded DNA (Fc-ssDNA) on the surface of the BNQDs, the ECL emission signal of the BNQDs was difficult to be observed by the naked eye, while [Ru(bpy)3](PF6)2 emitted a strong and visible ECL signal. In the presence of the target, bipedal DNA assembled by catalytic hairpin assembly (CHA) took away the Fc-ssDNA and the ECL intensity of the BNQDs was enlarged, and as the concentration of miRNA-141 increased to the cutoff value, yellow-green light was visible by the naked eye. Meanwhile, the red emission signal of [Ru(bpy)3](PF6)2/TPrA became weakened. Thus, an ultrasensitive "color switch" ECL biosensor for detection of miRNA-141 was constructed and endowed with a wide linear range from 10-17 to 10-7 M and a detection limit of 10-17 M (S/N = 3). This study provides the potential for investigating portable devices in the detection of low-concentration nucleic acids.

Bipolar electrode ratiometric electrochemiluminescence biosensing analysis based on boron nitride quantum dots and biological release system.

In this article, we developed a novel ECL ratiometry on a closed bipolar electrode (BPE) for the sensitively and accurately detection of miRNA-21. High quantum yield and low toxicity BNQDs was synthesized and coated at BPE cathode as an ECL emitter, while the anode of BPE was calibrated via another ECL material, Ir(df-ppy)2(pic) (Firpic). The electron neutrality at both ends of the BPE electrically coupled the reactions on each pole of the BPE. Therefore, one electrochemical sensing reaction could be quantified at one end of the BPE. By the hybridization of target miRNA-21 and hairpin, the glucose blocked in MSNs by the hairpin was released and reacted with glucose oxidase (GOD) to generate H2O2, thereby reducing the ECL signal of the cathode BNQDs/K2S2O8 system and promoting ECL signal of anode Firpic/TPrA. Further, the G-quadruplex formed by unreacted hairpin bases consumed H2O2, which not only recovered the ECL of BNQDs, but also further improved the ECL emission of Firpic. Therefore, the concentration of miRNA-21 could be measured by the ECL ratio of BNQDs and Firpic. The data showed that the detection limit was 10-15 M (S/N = 3) with the linear range of 10-15 M to 10-9 M. The strategy of the BPE-ECL ratio method based on BNQDs showed a good prospect in clinical application.

Transcriptomic Changes of Astrocytes in the Brain of Rats with Subacute METH Exposure.

OBJECTIVES: To study the transcriptomic changes of astrocytes in the brain of rats exposed to methamphetamine (METH) and its possible mechanism in neurotoxicity. METHODS: The rats were intraperitoneally injected with METH (15 mg/kg) every 12 h for 8 times in total to establish the subacute rat model of METH. After the model was successfully established, the striatum was extracted, and astrocytes were separated by the magnetic bead method. Transcriptome sequencing was performed on selected astrocytes, and the differentially expressed genes were analyzed by gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis. RESULTS: A total of 876 differentially expressed genes were obtained by transcriptome sequencing, including 321 up-regulated genes and 555 down-regulated genes. GO analysis revealed that differentially expressed genes were mainly concentrated in cell structure, biological process regulation, extracellular matrix and organelle functions. KEGG pathway enrichment analysis showed that steroids biosynthesis, fatty acid biosynthesis, peroxisome proliferators-activated receptor (PPAR), adenosine 5'-monophosphate-activated protein kinase (AMPK) and other signaling pathways were significantly changed. CONCLUSIONS: METH can cause structural changes of astrocytes through multiple targets, among which cellular structure, steroids biosynthesis and fatty acid biosynthesis may play an important role in nerve injury, providing a new idea for forensic identification of METH related death.

Sudden infant death from neonate carnitine palmitoyl transferase II deficiency.

A full-term female baby born to parents who gave birth three years prior to a girl who survived only 31h postpartum died 36h after birth. An autopsy showed that the heart was markedly hypertrophic (32g). Microscopically, the myocardium, liver and kidney cells exhibited extensive vacuolar degeneration. Sudan III staining was positive in cardiac muscle, liver and kidney tissue. Tandem mass spectrometry analysis revealed that the deceased patient had a carnitine palmitoyl transferase II (CPT2) deficiency or a carnitine-acylcarnitine translocase deficiency. Genetic testing of the parents revealed heterozygous CPT2 mutations, indicating that their offspring would have a 25% chance of having a CPT2 deficiency. Therefore, we speculated that CPT2 deficiency might be the cause of death based on the results of staining, tandem mass spectrometry analysis and parental genetic testing.

Toll-Like Receptor 4 Mediates Methamphetamine-Induced Neuroinflammation through Caspase-11 Signaling Pathway in Astrocytes.

Methamphetamine (METH) is an amphetamine-typed stimulant drug that is increasingly being abused worldwide. Previous studies have shown that METH toxicity is systemic, especially targeting dopaminergic neurons in the central nervous system (CNS). However, the role of neuroinflammation in METH neurotoxicity remains unclear. We hypothesized that Toll-like receptor 4 (TLR4) and Caspase-11 are involved in METH-induced astrocyte-related neuroinflammation. We tested our hypothesis by examining the changes of TLR4 and Caspase-11 protein expression in primary cultured C57BL/6 mouse astrocytes and in the midbrain and striatum of mice exposed to METH with western blot and double immunofluorescence labeling. We also determined the effects of blocking Caspase-11 expression with wedelolactone (a specific inhibitor of Caspase-11) or siRNA on METH-induced neuroinflammation in astrocytes. Furthermore, we determined the effects of blocking TLR4 expression with TAK-242 (a specific inhibitor of TLR4) or siRNA on METH-induced neuroinflammation in astrocytes. METH exposure increased Caspase-11 and TLR4 expression both in vitro and in vivo, with the effects in vitro being dose-dependent. Inhibition of Caspase-11 expression with either wedelolactone or siRNAs reduced the expression of inflammasome NLRP3 and pro-inflammatory cytokines. In addition, blocking TLR4 expression inhibited METH-induced activation of NF-κB and Caspase-11 in vitro and in vivo, suggesting that TLR4-Caspase-11 pathway is involved in METH-induced neuroinflammation. These results indicate that Caspase-11 and TLR4 play an important role in METH-induced neuroinflammation and may be potential gene targets for therapeutics in METH-caused neurotoxicity.

S-Nitrosylating protein disulphide isomerase mediates α-synuclein aggregation caused by methamphetamine exposure in PC12 cells.

Methamphetamine (METH) belongs to Amphetamine-type stimulants, METH abusers are at high risk of neurodegenerative disorders, including Parkinson's disease (PD). However, there are still no effective treatments to METH-induced neurodegeneration because its mechanism remains unknown. In order to investigate METH's neurotoxic mechanism, we established an in vitro PD pathology model by exposing PC12 cells to METH. We found the expression of nitric oxide synthase (NOS), nitric oxide (NO) and α-synuclein (α-syn) was significantly increased after METH treatment for 24h, in addition, the aggregattion of α-syn and the S-nitrosylation of protein disulphideisomerase(PDI) were also obviously enhanced. When we exposed PC12 cells to the NOS inhibitor N-nitro-L-arginine(L-NNA) with METH together, the L-NNA obviously inhibited these changes induced by METH. While when we exposed PC12 cells to the precursor of NO L-Arginine together with METH, the L-Arginine resulted in the opposite effect compared to L-NNA. And when we knocked down the PDI gene, the L-NNA did not have this effect. Therefore, PDI plays a significant role in neurological disorders related to α-syn aggregation, and it suggests that PDI could be as a potential target to prevent METH-induced neurodegeneration.

Effect of copper on the degradation of pesticides cypermethrin and cyhalothrin.

The influence of coexisting copper (Cu) ion on the degradation of pesticides pyrethroid cypermethrin and cyhalothrin in soil and photodegradation in water system were studied. Serial concentrations of the pesticides with the addition of copper ion were spiked in the soil and incubated for a regular period of time, the analysis of the extracts from the soil was carried out using gas chromatography (GC). The photodegradation of pyrethroids in water system was conducted under UV irradiation. The effect of Cu2+ on the pesticides degradation was measured with half life (t0.5) of degradation. It was found that a negative correlation between the degradation of the pyrethroid pesticides in soil and Cu addition was observed. But Cu2+ could accelerate photodegradation of the pyrethroids in water. The t0.5 for cyhalothrin extended from 6.7 to 6.8 d while for cypermethrin extended from 8.1 to 10.9 d with the presence of copper ion in soil. As for photodegradation, t0.5 for cyhalothrin reduced from 173.3 to 115.5 min and for cypermethrin from 115.5 to 99.0 min. The results suggested that copper influenced the degradation of the pesticides in soil by affecting the activity of microorganisms. However, it had catalyst tendency for photodegradation in water system. The difference for the degradation efficiency of pyrethroid isomers in soil was also observed. Copper could obviously accelerate the degradation of some special isomers.