A novel RhB@MOF-808 fluorescent probe for the rapid detection of dopamine and Fe3.

Dopamine (DA) and Fe3+ as the important bioactive ingredients, playing an indispensable role in human metabolism. Therefore, developing the accurate detection of DA and Fe3+ is of great significance for disease screening. Herein, we put forward a simple, rapid, and sensitive fluorescent detection strategy for the detection of dopamine and Fe3+ based on Rhodamine B-modified MOF-808 (RhB@MOF-808). RhB@MOF-808 produced strong fluorescence at 580 nm, and the fluorescence was significantly quenched after DA or Fe3+ was added, which was regarded as a static quenching process. Detection limits are as low as 60.25 nM and 48.34 nM, respectively. Furthermore, based on the responses of DA and Fe3+ to the probe, molecular logic gates were successfully designed. More importantly, RhB@MOF-808 had excellent cell membrane permeability and had been successfully used to label DA and Fe3+ in Hela cells, which presented a potential biological application value as a fluorescent probe for detecting DA and Fe3+.

Surface plasmon-assisted catalytic reduction of p-nitrothiophenol for the detection of Fe2+ by surface-enhanced Raman spectroscopy.

Herein, we developed a concise, time-efficient, and high selective assay for detecting Fe2+ through its triggered surface plasmon-assisted reduction reaction of p-nitrothiophenol (PNTP) to p,p'-dimercaptoazobenzene (DMAB) on the surface of gold nanoparticles (AuNPs) based on surface-enhanced Raman scattering (SERS) spectroscopy. When Fe2+ was added to the PNTP-AuNPs system, the appearance of three characteristic peaks at 1142, 1392, and 1440 cm-1 attributed to DMAB demonstrated that Fe2+ induced the catalytic coupling reaction of PNTP. The Raman intensity ratio of the peak at 1142 cm-1 to the peak at 1336 cm-1 and the concentration of Fe2+ presented a good linear response from 10 to 100 µM with a limit of detection (LOD) of 0.35 µM. More importantly, the entire detection process can be completed within 2 min and further successfully used for the detection of Fe2+ in river water.

Iridium-catalyzed diastereoselective amination of alcohols with chiral tert-butanesulfinamide by the use of a borrowing hydrogen methodology.

An iridium-catalyzed diastereoselective amination of alcohols with chiral tert-butanesulfinamide was developed under basic conditions, affording the optically active secondary sulfinamides in high yields and diastereoselectivities. The removal of the sulfinyl group from sulfonamides allowed a facile access to a wide range of α-chiral primary amines. This synthetic strategy was further applied in the synthesis of the marketed pharmaceuticals (S)-rivastigmine and NPS R-568.

Stereoconvergent, Redox-Neutral Access to Tetrahydroquinoxalines through Relay Epoxide Opening/Amination of Alcohols.

We present an economical catalytic procedure to convert readily available 1,2-diaminobenzenes and terminal epoxides into valuable 1,2,3,4-tetrahydroquinoxalines in a highly enantioselective fashion. This procedure operates through relay zinc and iridium catalysis, and achieves redox-neutral and stereoconvergent production of valuable chiral heterocycles from racemic starting materials with water as the only side product. The use of commercially available reagents and catalysts and a convenient procedure also make this catalytic method attractive for practical application.

Difunctional AuNPs@PVP with oxidase-like activity for SERRS detection of total antioxidant capacity.

Assessing the total antioxidant capacity (TAC) of foods plays a significant role in dietary guidance and disease risk reduction. Therefore, building a simple, rapid, and sensitive sensing method for detecting TAC possesses broad application prospects. Herein, we constructed a novel nanozyme catalyzed‒surface-enhanced Raman resonance scattering (SERRS) sensing strategy for analysis of TAC based on polyvinylpyrrolidone coated gold nanoparticles (AuNPs@PVP) that was synthesized by one step reduction method. AuNPs@PVP not only served as the SERRS substrate but also possessed high oxidase activity which can catalyze 3,3',5,5'-tetramethylbenzidine (TMB) oxidation by generating hydroxyl radicals (•OH) and superoxide anion free radical (•O2-). According to the inhibiting effect of antioxidants, ascorbic acid (AA) was selected as the representative for TAC detection. The linear range and limit of detection (LOD) were determined to be 10-8‒10-5 M and 0.6 nM, respectively. More importantly, the proposed nanozyme catalyzed‒SERRS strategy has been successfully applied to the detection of TAC in fruit juices, demonstrating promising potential in the field of food supervision and healthcare applications.

Dual detection and quantification of hypochlorite and sulfite ions via SERS spectroscopy by utilizing the redox reaction of tetramethylbenzidine.

We developed a highly efficient, ultra-sensitive, and selective dual detection sensor for hypochlorite (ClO-) and sulfite (SO32-) ions based on surface-enhanced Raman scattering (SERS) spectroscopy. 3,3',5,5'-Tetramethylbenzidine (TMB) is oxidized by ClO- under acidic conditions to diazotized oxTMB that, when electrostatically adsorbed onto Au nanoparticles (NPs), produces a strong Raman signal at 1605 cm-1. Meanwhile, oxTMB is reduced to TMB by SO32-, which significantly reduces the Raman signal. The linear detection range of the proposed sensor is 10-10 to 10-6 M with a detection limit of 59 pM for ClO- and 10-9 to 10-5 M with a detection limit of 5.4 nM for SO32-. In addition, the sensor was successfully applied to detect ClO- and SO32- in water samples.

Sulfite-triggered surface plasmon-catalyzed reduction of p-nitrothiophenol to p,p'-dimercaptoazobenzene.

The conversion of p-aminothiophenol (PATP) or p-nitrothiophenol (PNTP) to p,p'-dimercaptoazobenzene (DMAB) has been used as model reactions to study plasmon-catalyzed reaction on nanoparticles. Herein, we report the conversion of PNTP to DMAB which is triggered by SO32- ions on gold nanoparticles (AuNPs) for the first time. With the addition of SO32-, the Raman peaks at 1139, 1392, 1437 cm-1 appears, which indicates the formation of DMAB. The experiment results suggested that the synergistic effect of AuNPs and SO32- promoted the conversion of PNTP to DMAB. Besides, the proposed catalysis system is high selectivity to SO32- ions, which provides a new detection route to SO32- ions in the future. More importantly, the possible reaction mechanism has been put forward which is helpful to understand the surface plasmon-assisted catalytic reduction of PNTP on the surface of SERS substrate.

A sensitive surface-enhanced resonance Raman scattering sensor with bifunctional negatively charged gold nanoparticles for the determination of Cr(VI).

Hexavalent chromium (Cr(VI)) pollution in the water system has seriously endangered human health and the environment. Herein, we propose a rapid, simple and sensitive surface-enhanced resonance Raman scattering (SERRS) sensor with the bifunctional negatively charged gold nanoparticles ((-)AuNPs) which employ as not only the oxidoreductase-like nanozyme but also the substrate to determine Cr(VI). (-)AuNPs effectively promoted the conversion of 3,3',5,5'-tetramethylbenzidine (TMB) into the blue product of 3,3',5,5'-tetramethylbenzidine diamine (oxTMB) in the presence of Cr(VI) and generated a strong SERRS signal at 1611 cm-1. According to this principle, the Raman intensity difference at 1611 cm-1 exhibited a satisfactory linear relationship with the logarithm of the Cr(VI) concentration from 10-5 to 10-9 M with a low limit of detection (LOD) of 0.4 nM. In addition, the possible SERRS enhancement mechanism, selectivity and reproducibility were also investigated. What's more, the SERRS platform was successfully applied in the complicated water samples, which was anticipated to become a promising analytical method for monitoring of Cr(VI) in the environment.

An ultrasensitive surface-enhanced Raman scattering sensor for the detection of hydrazine via the Schiff base reaction.

The development of convenient assays for the determination of hydrazine (N2H4) has drawn significant attention due to the high toxicity of this substance. Herein, we developed a concise, rapid and ultrasensitive surface-enhanced Raman scattering (SERS) sensor for N2H4 detection based on alpha-cyclodextrin-silver nanoparticles (α-CD-AgNPs) modified by 4-mercaptobenzaldehyde (4-MBA). The 4-MBA molecules can specifically capture the N2H4 molecules and undergo a Schiff base reaction. As a result, this induces the aggregation of nanoparticles and generates a new characteristic peak at 1529 cm-1 that is attributed to CN and CC vibrations. Compared with noble metal nanoparticles, 4-MBA not only formed AgS bonds but could also be fixed in the cavity of cyclodextrin to produce a more stable and stronger SERS signal. The SERS intensity at 1529 cm-1 and the logarithm of the concentration of N2H4 presented a good linear relationship from 10-9 to 10-7 M with an unprecedented limit of detection (LOD) of 38 pM. The proposed SERS sensor exhibited satisfactory selectivity and reproducibility and was applied to detect N2H4 in real and complex water samples. We expect this assay to be a promising alternative tool for the on-site detection of N2H4.

Correlation between preoperative inflammatory markers, Ki-67 and the pathological grade of glioma.

ABSTRACT: To investigate the correlation between preoperative inflammatory markers, Ki-67 expression and the pathological grade of glioma, and to provide a reference for clinical prediction of glioma prognosis.A total of 45 glioma patients who underwent surgery with complete clinical and pathological data were in our hospital from January 2012 to December 2018 were enrolled. Glioma was divided into WHO grade I to IV. Forty-five healthy health examiners with matched clinical characteristics were included to the control group. Blood routine tests were recorded at admission in both the glioma and control group. The ratio of neutrophil to lymphocyte cytometry (NLR), derived neutrophil to lymphocyte ratio (dNLR) (white blood cell count - neutrophil count to neutrophil count), platelet to lymphocyte ratio (PLR) and prognostic nutritional index (PNI, serum albumin content + 5 × lymphocyte count) were calculated. The expression of Ki-67 in glioma was detected by immunohistochemistry. The relationship between the above markers, Ki-67 expression and pathological grade of glioma was evaluated with receiver operating characteristics curve analysis and Spearman correlation test. The correlation between the markers and Ki-67 were also determined.NLR, dNLR, PLR were increased in the glioma group (P < .001, <.001, .002), whereas red blood cell distribution width (RDW) was decreased (P = .009). All the glioma samples expressed Ki-67 with varying degree. Receiver operating characteristics curve analysis reveals NLR, dNLR, PLR, and RDW have significant discriminating ability in differentiating the glioma and control sample. NLR, PLR, PNI, and Ki-67 were significantly correlated with glioma pathology grade (P = .023, .006, .019, <.05), while dNLR and RDW were not associated with glioma grade. Finally, NLR and PLR were related to Ki-67 expression in glioma patients (P = .002, .022), while dNLR and RDW were not related to Ki-67 expression.Preoperative inflammatory markers NLR, PLR, PNI, and postoperative Ki-67 expression are associated with pathological grade of glioma. Detection of these markers may aid in better prediction of glioma prognosis.

In-Situ Synthesis of Methyl Cellulose Film Decorated with Silver Nanoparticles as a Flexible Surface-Enhanced Raman Substrate for the Rapid Detection of Pesticide Residues in Fruits and Vegetables.

The purpose of this study was to develop a flexible substrate methylcellulose-decorated silver nanoparticles (MC/Ag NPs) film and explore its application in fruits and vegetables by surface enhanced Raman spectroscopy (SERS) technology for rapid detection of pesticides. The performance of the MC/Ag NPs film substrate was characterized by Nile blue A (NBA), and the detection limit was as low as 10-8 M. The substrate also exhibited satisfactory Raman signal strength after two months of storage. The impressive sensitivity and stability were due to the excellent homogeneity of the silver nanoparticles that were grown in situ in the methylcellulose matrix, which generated "hot spots" between the silver nanoparticles without a large amount of aggregation, and resulted in the ultra-high sensitivity and excellent stability of the MC/Ag NPs film substrate. The MC/Ag NPs film substrate was used to detect thiram pesticides on tomato and cucumber peels, and the minimum detectable level of thiram was 2.4 ng/cm2, which was much lower than the maximum residue level. These results indicate that the MC/Ag NPs film is sensitive to rapid detection of multiple pesticides in food.

Standardized Ginkgo biloba extract EGb 761® attenuates early brain injury following subarachnoid hemorrhage via suppressing neuronal apoptosis through the activation of Akt signaling.

BACKGROUND: Early brain injury (EBI) plays a critical role in determining the outcome of subarachnoid hemorrhage (SAH). The present study was designed to investigate the role of EGb 761, a standardized extract of Ginkgo biloba, in SAH-induced EBI and to explore its potential mechanism of action. METHOD: A rat SAH model was established by the endovascular perforation process. Doses of 10, 50 and 100 mg/kg EGb 761 were injected intraperitoneally 2 h after SAH was induced. Mortality, SAH grade, neurological score and brain water content were measured 24 h after SAH was induced. A Western blot assay was performed to assess the expression of the apoptosis-related proteins Bax, Bcl-2, cleaved caspase-3, Akt and phosphorylated Akt (p-Akt). Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) and neuronal nuclei (NeuN) double immunofluorescence staining were used to detect apoptotic neurons. RESULTS: Animals suffered from serious neurological deficits and increased brain water content after induction of SAH. Rats treated with EGb 761 experienced dose-dependent attenuation of neurological dysfunction and decreased brain water content. In addition, EGb 761 significantly activated Akt signaling accompanied by increased Bcl-2 levels and decreased expression of Bax and cleaved caspase-3. Moreover, EGb 761 decreased the number of TUNEL/NeuN-positive cells in a dose-dependent manner. However, all the beneficial effects of EGb 761 for SAH were abolished by the Akt inhibitor MK2206. CONCLUSION: Our results indicated that EGb 761 could ameliorate SAH-induced EBI and that the neuroprotective effects of EGb 761 against SAH were exerted via suppression of neuronal apoptosis through activation of the Akt pathway.