A novel bifunctional molecularly imprinted polymer-based SERS/RRS dimode nanosensor for ultratrace acetamiprid.

A new acetamiprid (AP) molecularly imprinted polymer (MIP) nanosol was synthesized with α-methacrylic acid as functional monomer, ethylene glycol dimethacrylate as crosslinker and 2,2'-azobisisobutyronitrile as initiator, under the microwave irradiation. It was characterized by transmission electron microscopy, specific surface area and pore size analysis, and molecular spectroscopy. The bifunctional MIP nanomaterial not only had the recognition of AP but also had a strong catalysis of the nanogold dimode indicator reaction of chloroauric acid-dopamine. The generated gold nanoparticles (AuNPs) had strong surface-enhanced Raman scattering (SERS) and resonance Rayleigh scattering (RRS) effects, and the two kinds of signals enhanced linearly with imprinted molecule AP increasing. Accordingly, a novel SERS/RRS nanosensor platform was constructed to detect 0.25-20 pmol/L and 0.5-50 pmol/L AP by SERS and RRS monitoring respectively. Moreover, a reliable nanocatalytic mechanism was proposed.

MXene nanosheet loaded gold nanocluster catalytic amplification-aptamer SERS quantitative assay platform for isocarbophos.

The traditional preparation of MXeneTi3C2 is complicated. Two-dimensional MXeneTi3C2 nanosheets were prepared via in-situ generation of HF etching Ti3AlC2 under the microwave irradiation. Gold nanocluster doped nanosheets sol (MXene@Au) with excellent stability and strong catalysis was synthesized with no product residue reducer CO. MXene@Au nanosol can catalyze mandelic acid-HAuCl4 to produce gold nanoparticles, which can be traced via resonance Rayleigh scattering (RRS) and surface-enhanced Raman scattering (SERS). Coupled the dual-mode nanocatalytic indicator reaction with aptamer reaction, a high sensitivity, selectivity, facile SERS/RRS dual-mode biosensnoring assay platform has been constructed for isocarbophos (ICP). The linear range of SERS was 1.0 × 10-3-2.5 × 10-2 nmol/L, with a detection of limit 4.5 × 10-5 nmol/L (S/N = 3). It has been used to detect ICP in water samples, with a good recovery (95.5-104%) and a good relative standard deviation (5.2-9.6%). This new nanocatalytic amplification biosensoring strategy can also assay other organic pesticides including malathion, glyphosate, profenofos and carbendazim. In addition, the nanocatalytic mechanism was investigated.

A facile COF loaded-molybdate resonance Rayleigh scattering and fluorescence dimode probe for determination of trace PO43.

A new covalent organic framework loaded-molybdate (COFMo) nanomaterial was prepared simply by solvothermal procedure and characterized by electron microscopy and molecular spectral techniques. The COFMo had a strong resonance Rayleigh scattering (RRS) signal at 465 nm and a fluorescence peak at 345 nm. When the PO43- was added in the system, it reacted with the molybdate, which loaded on the surface of COF particles, to form stable phosphomolybdic acid occurring RRS/fluorescence-energy transfer, the RRS and fluorescence signals were decreased. The decreased RRS/fluorescence intensities were linear to the PO43- concentration in the range of 0.053-3.2 nmol/L and 0.10-3.2 nmol/L, with a detection limit of 0.050 nmol/L and 0.090 nmol/L respectively. Accordingly, a new and facile RRS/fluorescence dimode method for detection of trace PO43- was established, only one fluorometer was used.

Highly catalysis amplification of MOFNd-loaded nanogold combined with specific aptamer SERS/RRS assay of trace glyphosate.

A neodymium metal-organic framework (MOFNd) was prepared using 1H-pyrazole-3,5-dicarboxylic acid (H3pdc) and 2-pyrazinecarboxylic acid as ligands. Through the addition of HAuCl4 as a precursor and NaBH4 as a reducing agent, a new MOFNd-loaded nanogold (AuNPs) (Au@MOFNd) nanosol with good stability and high catalytic activity was conveniently prepared via a solvothermal-reduction method and characterized. It was found that the indicator reaction of reducing HAuCl4 by Na2SO3 to generate AuNPs was slow. Au@MOFNd strongly catalyzes this nanoreaction, and the produced AuNPs exhibit a strong resonance Rayleigh scattering (RRS) peak at 370 nm, and a strong surface-enhanced Raman scattering (SERS) peak at 1617 cm-1 with the addition of the molecular probe Victoria blue 4R (VB4r). A novel SERS/RRS di-mode quantitative analysis method for glyphosate (GLY) was established by coupling this new Au@MOFNd catalytic indicator reaction with the aptamer (Apt) reaction of GLY, with SERS and RRS detection limits of 0.02 nM and 0.3 nM, respectively. It has been applied to the analysis of soil samples with a recovery rate of 93.0%-106.5% and precision of 2.2%-4.1%, and the results were satisfactory.

Highly catalysis MOFCe supported Ag nanoclusters coupled with specific aptamer for SERS quantitative assay of trace dopamine.

A cerium metal organic framework-loaded silver nanocluster (MOFCeAgNC) is synthesized by a facile stirring procedure with trimesic acid, cerium nitrate, silver nitrate and NaBH4, which exhibites strong catalytic activity in the indicated reaction of HAuCl4-sodium lactate (SL). MOFCeAgNC can sensitively detect dopamine (DA) by surface-enhanced Raman scattering (SERS) and resonance Rayleigh scattering (RRS) techniques with a detection concentration range of 0.01-0.25 nmol/L and a detection limit of 0.008 nmol/L. Based on the specific binding of aptamer (Apt)-DA and the catalytic amplification strategy of MOFCeAgNC on HAuCl4-SL, a sensitive and convenient DA platform for dual-mode detection of SERS and RRS is constructed. In addition, the platform is successfully applied to detect DA in human serum with satisfactory recoveries (95.7-102%).

A novel aptamer RRS assay platform for ultratrace melamine based on COF-loaded Pd nanocluster catalytic amplification.

Two COFs of BzBD and BzBD loaded Pd nanoclusters (BzBDPd) were prepared using 1,3,5-benzenetricarboxaldehyde (Bz), benzidine (BD) and CO reducing agent, and were characterized by transmission electron microscopy (TEM), X-ray powder diffraction (XRD), infrared spectroscopy (IR) and other techniques. BzBDPd can strongly catalyze the new and stable Au@NiP nanoreaction that exhibit a strong resonance Rayleigh scattering (RRS) peak at 538 nm and a surface plasmon resonance (SPR) absorption peak at 395 nm, and the sensitive and facile RRS technique was used to study the indicator reaction. Combining the nanocatalytic amplification reaction with specific aptamer (Apt) of some target molecules such as melamine (ML), urea (UR) and bisphenol A (BPA), a simple, sensitive and selective Apt RRS assay platform was established. The linear range of the RRS detection platform for melamine is 0.0025-0.04 nmol/L, and the detection limit (DL) is 1.96 × 10-4 nmol/L. In addition, ML in real sample was analyzed, the stability of BzBD, BzBDPd, PdNPs and the catalytic mechanism of COFPd were also considered.

A new gold nanoflower sol SERS method for trace iodine ion based on catalytic amplification.

As one of the essential trace elements in metabolism, iodine is crucial to maintain the normal physiological functions. Therefore, based on health and environmental protection, it is very important to realize sensitive detection of iodide ion. Herein, we developed a simple, rapid and sensitive method for the determination of iodide ion. Trypsin was used as an ideal template for the synthesis of gold nanoflower sol (AuNFs) with anisotropic surface structure and good stability. It exhibits highly active surface enhanced Raman scattering (SERS) effect and can be used as facile SERS sol substrate. The TMBox generated by the catalytic oxidation reaction of TMB-chloramine T-iodide ion is used as the SERS probe. The enhanced SERS signal intensity is linearly related to the iodide ion with high sensitivity. In addition, TMB has fluorescence effect, and the colored TMBox can produce RRS signal due to polymerization. Based on this, a quad-mode detection method of SERS, RRS, fluorescence and colorimetry for quantitative detection of trace iodide ions was established, and this method can be applied to the detection of iodide ions in natural water and drinking water.

Performance of modified carbapenem inactivation method and inhibitor-based combined disk test in the detection and distinguishing of carbapenemase producing Enterobacteriaceae.

BACKGROUND: This study aimed to evaluate the performance of modified carbapenem inactivation method (mCIM) combined EDTA-carbapenem inactivation method (eCIM), and inhibitor-based combined disk test (CDT) in the detection and distinguishing of carbapenemase production in Enterobacteriaceae. METHODS: A total of 101 nonrepetitive carbapenem insensitive Enterobacteriaceae [minimal inhibitory concentration (MIC) ≥2 µg/mL] were tested by mCIM, eCIM and CDT respectively, and the major carbapenemase genes including blaKPC, blaNDM, blaIMP, blaVIM and blaOXA-48-like genes were detected by polymerase chain reaction (PCR) as control. RESULTS: Seventy-nine (78.2%) of isolates were found to harbour one or more carbapenemase genes by PCR, with blaKPC and blaNDM being the most common genes. OXA-48-like genes were undetectable. The coincidence rate of mCIM combined eCIM and CDT was 97.5% (77/79) and 96.2% (76/79) respectively, compared with gene detection. Both assays had a misclassification in two blaKPC+NDM-producing isolates of Klebsiella oxytoca. The sensitivity and specificity of two assays above were 100.0% vs. 95.0% and 98.4% vs. 98.4%, respectively in distinguishing serine-carbapenemase, while they were 95.1% vs. 97.6% and 100% vs. 100.0%, respectively in distinguishing metallo-carbapenemase. CONCLUSIONS: mCIM combined eCIM and the CDT are both useful tools for the reliable detection and distinguishing single serine-carbapenemase or metallo-carbapenemase, but not for mixed types.

Necrostatin-1 Improves Long-term Functional Recovery Through Protecting Oligodendrocyte Precursor Cells After Transient Focal Cerebral Ischemia in Mice.

Ischemic stroke often results in severe injury to white matter structures including the axons, oligodendroglia, and other glial cells. Immature stages of oligodendroglia, such as oligodendrocyte precursor cells (OPCs) and premature oligodendroglia, are more vulnerable to ischemia than mature oligodendroglia. Extensive studies have been performed on the necroptosis of neurons following cerebral ischemia. The present study aimed to investigate the effect of necrostatin-1 (Nec-1), a necroptosis inhibitor, on the survival of OPCs and long-term functional recovery following transient cerebral ischemia. Male adult ICR mice (25-30 g) were subjected to 60-min middle cerebral artery occlusion (MCAO) and 24 h of reperfusion. Nec-1 (0.04 mg/kg) was injected intracerebroventricularly 1 h before the onset of MCAO. Cognitive functions were evaluated ≤30 days after MCAO. Necroptosis-related proteins, receptor-interacting protein kinase 1 (RIPK1), RIPK3, MLKL, and P-MLKL, were assessed by western blot analyses. The cultured primary mouse OPCs were used to confirm the effects of Nec-1 on the viability of OPCs following oxygen-glucose deprivation (OGD). This study demonstrated that pretreatment with Nec-1 significantly promoted OPCs survival, alleviated white matter injury, and improved cognitive function after transient cerebral ischemia. Nec-1 also inhibited the activation of RIPK1, RIPK3, MLKL, and P-MLKL in the subventricular zone (SVZ) and corpus callosum regions after MCAO. OPCs' culture experiments confirmed that Nec-1 significantly reduced the necroptosis of OPCs, perhaps by inhibiting the expression of RIPK1, RIPK3, MLKL, and P-MLKL. Nec-1, an inhibitor of RIPK1, may reduce ischemic white matter damage and improve recovery of long-term neurological function following cerebral ischemia.

Lead induces apoptosis in mouse TM3 Leydig cells through the Fas/FasL death receptor pathway.

The study was aimed to investigate the effect of Pb toxicity on mouse Leydig cells and its molecular mechanism. The TM3 cells were cultured in vitro and exposed to Pb at different concentrations for 24h. The effects of Pb on cell proliferation and apoptosis were analyzed with MTT and Annexin V-FITC/PI via flow cytometry, respectively. Expression levels of Fas, Fas-L and caspase-8 in TM3 cells were determined by western blot. As well as the inhibitory effect of the caspase-8 inhibitor Z-IETD-FMK on cell apoptosis. We found that Pb treatment significantly decreased the cellar viability (P<0.05), increased the apoptosis (P<0.01) and the Fas, FasL, and caspase-8 expression levels in Pb-treated cells as compared to the control cells (P<0.05 or P<0.01). Furthermore, the caspase-8 inhibitor effectively block the Pb-induced cell apoptosis. Taken together, our data suggest that Pb-induced TM3 cell toxic effect may involve in the Fas/FasL death receptor signaling pathway.

Analysis and prediction of single-stranded and double-stranded DNA binding proteins based on protein sequences.

BACKGROUND: DNA-binding proteins perform important functions in a great number of biological activities. DNA-binding proteins can interact with ssDNA (single-stranded DNA) or dsDNA (double-stranded DNA), and DNA-binding proteins can be categorized as single-stranded DNA-binding proteins (SSBs) and double-stranded DNA-binding proteins (DSBs). The identification of DNA-binding proteins from amino acid sequences can help to annotate protein functions and understand the binding specificity. In this study, we systematically consider a variety of schemes to represent protein sequences: OAAC (overall amino acid composition) features, dipeptide compositions, PSSM (position-specific scoring matrix profiles) and split amino acid composition (SAA), and then we adopt SVM (support vector machine) and RF (random forest) classification model to distinguish SSBs from DSBs. RESULTS: Our results suggest that some sequence features can significantly differentiate DSBs and SSBs. Evaluated by 10 fold cross-validation on the benchmark datasets, our prediction method can achieve the accuracy of 88.7% and AUC (area under the curve) of 0.919. Moreover, our method has good performance in independent testing. CONCLUSIONS: Using various sequence-derived features, a novel method is proposed to distinguish DSBs and SSBs accurately. The method also explores novel features, which could be helpful to discover the binding specificity of DNA-binding proteins.

Proprotein convertase subtilisin/kexin type 9 (PCSK9) in lipid metabolism, atherosclerosis and ischemic stroke.

Proprotein convertase subtilisin/kexin 9 (PCSK9) is the ninth member of the proprotein convertase family. It is an important regulator of cholesterol metabolism. PCSK9 can bind to low-density lipoprotein receptors (LDLRs) and induce the degradation of these receptors through the endosome/lysosome pathway, thus decreasing the LDLR levels on the cell surface of hepatocytes, resulting in increased serum low-density lipoprotein cholesterol (LDL-C) concentrations. Recent studies have found that gene polymorphisms of PCSK9 are associated with hypercholesterolemia, risk of atherosclerosis, and ischemic stroke. Furthermore, monoclonal antibodies, peptide mimetics, small molecule inhibitors and gene silencing agents that are associated with PCSK9 are some of the newer pharmaceutical therapeutic strategies and approaches for lowering serum LDL-C levels. In this review, we will discuss recent advances in PCSK9 research, which show that PCSK9 is correlated with lipid metabolism, atherosclerosis, and, in particular, ischemic stroke. We will also discuss the current state of PCSK9 therapeutics and their potential in modulating these diseases.

[Drug resistance and genotyping of Klebsiella pneumoniae in lower respiratory tract infection].

OBJECTIVE: To understand the current drug resistance of Klebsiella pneumoniae in lower respiratory tract infection and the prevalence trend of extended spectrum beta-lactamase (ESBLs)-producing Klebsiella pneumoniae. METHODS: Drug resistance in 86 strains of Klebsiella pneumoniae and ESBLs-producing strains were genotyped by randomly amplified DNA polymorphisms (RAPD). RESULTS: ESBLs-producing strains accounted for 20.9% of the 86 strains, and 83.3% of the ESBLs-producing strains were from respiratory ICU. The drug resistance rate of ESBLs positive bacteria was much higher than that of ESBLs negative bacteria. ESBLs positive bacteria were resistant to both the quinolones and a minoglylosides. Eighteen ESBLs-producing strains were divided into 12 types. 3 strains had the same profile (genotype A), and 5 strains had an identical profile (genotype B), but other strains had different profiles. CONCLUSIONS: Chromosomal DNA analysis proved that certain types of ESBLs-producing Klebsiella pneumoniae were epidemic in respiratory ICU. RAPD was an economic, simple but reliable method in epidemic study.