Organic polymer/inorganic heterostructure coupled with efficient allosteric bicycle strand displacement for photochemical sensing.

In this work, a high-performance conjugated microporous polymer (CMP) decorated with BiOBr (Tr(PhXOD)3-CMP/BiOBr) is synthesized to application in construction of ultrasensitive photoelectrochemical (PEC) biosensor for sensing miRNA-122, by firstly coupling with efficient clip toehold-mediated allosteric bicycle strand displacement (ABSD). Notably, the Tr(PhXOD)3-CMP/BiOBr not only owns self-enhanced D-A-D structure that extremely shortens migration distance of photo-generated electron, but also forms Z-type heterostructure for accelerating electron-hole separation, thereby significantly enhancing the photocurrent with 10-fold higher than commonly used methods. Meanwhile, the clip toehold-mediated ABSD based on ternary linkage structure transformation avoids the attrition of invading strand, endowing the conservation of high concentration for undergoing rapid reaction with high-efficiency DNA amplification, which dramatically improves reaction time and superior target conversion. The experimental results indicate that proposed PEC biosensor had a high sensitivity to miRNA-122 with a detection limit of 0.49 fM, which provides a newly organic/inorganic photosensitive nanomaterials and efficient DNA strand displacement in bioanalytical and early clinical disease diagnosis.

A robust and validated LC-MS/MS method for the quantification of ramucirumab in rat and human serum using direct enzymatic digestion without immunoassay.

A new liquid chromatography tandem mass spectrometry (LC-MS/MS) method was established to quantify the anti-gastric cancer fully human monoclonal antibody (ramucirumab) in rat and human serum. The surrogate peptide (GPSVLPLAPSSK) for ramucirumab was generated by trypsin hydrolysis and quantified using the isotopically labeled peptide GPSVLPLAPSSK[13C6, 15N2]ST containing two more amino acids at the carboxyl end as an internal standard to correct for variations introduced during the enzymatic hydrolysis process and any mass spectrometry changes. Additionally, the oxidation and deamidation of unstable peptides (VVSVLTVLHQDWLNGK and NSLYLQMNSLR) were detected. The quantitative range of the proposed method was 1-1000 µg/mL, and complete methodological validation was performed. The precision, accuracy, matrix effect, sensitivity, stability, selectivity, carryover, and interference of the measurements met the required standards. The validated LC-MS/MS method was applied to pharmacokinetic studies in rats administered ramucirumab at 15 mg/kg intravenously. Overall, a robust, efficient, and cost-effective LC-MS/MS method was successfully developed for quantifying ramucirumab in rat and human serum.

Long-Wavelength Illumination-Induced Photocurrent Enhancement of a ZnPc Photocathodic Material for Bioanalytical Applications.

Herein, a novel photocathodic nanocomposite poly{4,8-bis[5-(2-ethylhexyl)-thiophen-2-yl] benzo[1,2-b:4,5-b']dithiophene-2,6-diyl-alt-3-fluoro-2-[(2-ethylhexyl)-carbonyl]thieno[3,4-b]thiophene-4,6-diyl}/phthalocyanine zinc (PTB7-Th/ZnPc) with high photoelectric conversion efficiency under long-wavelength illumination was prepared to construct an ultrasensitive biosensor for the detection of microRNA-21 (miRNA-21), accompanied by a prominent anti-interference capability toward reductive substances. Impressively, the new heterojunction PTB7-Th/ZnPc nanocomposite could not only generate a strong cathodic photocurrent to improve the detection sensitivity under long-wavelength illumination (660 nm) but also effectively avoid the high damage of biological activity caused by short-wavelength light stimulation. Accordingly, by coupling with rolling circle amplification (RCA)-triggered DNA amplification to form functional biquencher nanospheres, a PEC biosensor was fabricated to realize the ultrasensitive analysis of miRNA-21 in the concentration range of 0.1 fM to 10 nM with a detection limit as low as 32 aM. This strategy provided a novel long-wavelength illumination-induced photocurrent enhancement photoactive material for a sensitive and low-damage anti-interference bioassay and early clinical disease diagnosis.

P3HT-PbS nanocomposites with mimicking enzyme as bi-enhancer for ultrasensitive photocathodic biosensor.

Photocathodic biosensor has great capability in anti-interference from reductive substances, however, the low signal intensity of photoactive species with inferior detection sensitivity restricts its wide application. In this work, the P3HT-PbS nanocomposites were synthesized as signal tags, by integrating with target-trigger generated hemin/G-quadruplex nanotail as bi-enhancer to significantly apmplify the photocurrent, an ultrasensitive photocathodic biosensor was proposed for detection of ß2-microglobulin (ß2-MG). Impressively, P3HT with cathode signal is an attractive polymer consisted of substantial thiophene groups with high absorption coefficient and mobility of photo-generated holes, which could anchor with the PbS dots as sensitizer, providing a high charge mobility and strong photosensitivity. More importantly, target-trigger generated hemin/G-quadruplexes could accept the electron from illuminated photoactive species through the conversion of Fe(III)/Fe(II) in hemin, effectively reducing charge recombination rate as well as accelerating the generation of electron acceptor O2 in the assistant of H2O2. Moreover, hemin/G-quadruplexes inherited the HRP mimicking catalytic capability that further improved the produce of plentiful O2. As a result, PEC cathode signal was significantly enhanced for sensitive analysis of ß2-MG protein with a good detection range of 0.1 pg/mL to 100 ng/mL. It would provide a path for establishing PEC platform with excellent anti-interference ability and extend the application of photoelectrochemical (PEC) biosensor in bioanalysis and early disease diagnosis.

Study on the clinical mechanism of Tong-Xie-An-Chang Decoction in the treatment of diarrheal irritable bowel syndrome based on single-cell sequencing technology.

BACKGROUND: Diarrhea-predominant irritable bowel syndrome (IBS-D) is a kind of functional gastrointestinal disorder with obscure pathogenesis, and exploration about differential gene expression and cell heterogeneity of T lymphocytes in peripheral blood in IBS-D patients still remains unknown. Clinicians tend to use symptomatic treatment, but the efficacy is unstable and symptoms are prone to relapse. Traditional Chinese Medicine (TCM) is used frequently in IBS-D with stable and lower adverse effects. Tong-Xie-An-Chang Decoction (TXACD) has been proven to be effective in the treatment of IBS-D. However, the underlying therapeutic mechanism remains unclear. This trial aims to evaluate the clinical efficacy and safety of TXACD in IBS-D and elucidate the gene-level mechanism of IBS-D and therapeutic targets of TXACD based on single-cell sequencing technology. METHODS/DESIGN: This is a randomized controlled, double-blind, double-simulation clinical trial in which 72 eligible participants with IBS-D and TCM syndrome of liver depression and spleen deficiency will be randomly allocated in the ratio of 1:1 to two groups: the experimental group and the control group. The experimental group receives Tong-Xie-An-Chang Decoction (TXACD) and Pinaverium bromide tablets placebo; the control group receives pinaverium bromide tablets and TXACD placebo. Each group will be treated for 4 weeks. The primary outcome: the rate of IBS-Symptom Severity Score (IBS-SSS). The secondary outcomes: TCM syndrome score, adequate relief and IBS-Quality of Life Questionnaire (IBS-QOL). Mechanistic outcome is the single-cell sequencing profiling of the T lymphocytes in peripheral blood from IBS-D participants before and after the treatment and healthy individuals. DISCUSSION: This trial will prove the efficacy and safety of TXACD with high-quality evidence and provide a comprehensive perspective on the molecular mechanism of IBS-D by single-cell sequencing profiling, which makes us pinpoint specific biomarkers of IBS-D and therapeutic targets of TXACD.

A DNA nanopillar as a scaffold to regulate the ratio and distance of mimic enzymes for an efficient cascade catalytic platform.

Herein, a rigid 3D DNA nanopillar was used to investigate the influence of spatial organization on the cascade activity in multienzyme systems, realizing controllable regulation of the mimic enzyme ratio and spacing for acquiring a high-efficiency enzyme cascade catalytic platform. Initially, the ratio of mimic enzyme AuNPs (glucose oxidase-like activity) and hemin/G-quadruplex DNAzyme (peroxidase-like activity) fixed at the designed position was adjusted by changing the number of edges in a DNA polyhedron, resulting in an optimal mimic enzyme ratio of 1 : 4 with a quadrangular prism as the scaffold. Notably, the DNA nanopillar formed by quadrangular prism layer-by-layer assembly acted as a track for directional and controllable movement of a bipedal DNA walker based on the toehold mediated strand displacement reaction (TSDR), which endowed the assay system with continuous enzyme spacing regulation compared with previous enzyme cascade systems that induced inflexible operation. Furthermore, enzyme mimetics in this work circumvented the drawbacks of natural enzymes, such as time-consuming purification processes and poor thermal stability. As a proof of concept, the proposed dual regulation strategy of cascade enzymes was applied in the ultrasensitive electrochemical detection of Pb2+, which provided a new route to fabrication of high-performance artificial enzyme cascade platforms for ultimate application in bioanalysis and biodiagnostics.

Novel D-A-D-Type Supramolecular Aggregates with High Photoelectric Activity for Construction of Ultrasensitive Photoelectrochemical Biosensor.

In this work, hydrazine-functionalized perylene diimide derivative supramolecular (HPDS), a novel self-enhanced donor-acceptor-donor (D-A-D) type aggregates with excellent photoelectric activity, was synthesized by a facile one-pot green route and further applied in construction of coreactant-free photoelectrochemical (PEC) biosensor for ultrasensitive DNA assay. Impressively, the HPDS formed by D-A-D units not only possessed effectively shorted electron-transfer path between donor and acceptor, but also presented a desiring aggregate state via the π-π stacking of perylene core and hydrogen bonding of the terminal moiety, thereby acquiring a high density electron flow for generating the extremely high PEC signal. Experimental data showed that the well film-formed HPDS aggregate could produce an exciting photocurrent intensity about 6-fold stronger than that of precursor perylene dianhydride with donor N2H4 in detection buffer and even 12-fold than that of perylene dianhydride only. In this respect, the resultant HPDS aggregate as a novel self-enhanced PEC signal tag was adopted to fabricate the coreactant-free PEC biosensor with the help of target dual-recycling-induced bipedal DNA walker cascade amplification strategy for ultrasensitive DNA (a fragment of TP53 gene) assay. The proposed biosensor showed a high sensitivity with a low detection limit down to femtomole level, providing a new avenue for sensitive bioanalysis and clinical diagnosis.

Ultrasensitive photoelectrochemical biosensor for MiRNA-21 assay based on target-catalyzed hairpin assembly coupled with distance-controllable multiple signal amplification.

Here, with the target-catalyzed hairpin assembly generated dsDNA (HP1-HP2) to synchronously control the departure of quencher ferrocene and approach of sensitizer methylene blue, a distance-controllable multiple signal amplification based photoelectrochemical biosensor was proposed for MiRNA-21 assay.

Ultrasensitive Photoelectrochemical Detection of Multiple Metal Ions Based on Wavelength-Resolved Dual-Signal Output Triggered by Click Reaction.

In this work, a click reaction-triggered wavelength-resolved dual-signal output photoelectrochemical (PEC) biosensor with DNAzymes-assisted cleavage recycling amplification was proposed for sensitive triplex metal ions assay. Substantial DNA fragments azido-S1 and azido-S2, derived from the Pb2+ (target 1) and Mg2+ (target 2) dependent cleavage cycle of DNAzymes, respectively, were grafted efficiently on the same alkynyl-DNA (capture DNA) modified electrode via the Cu2+ (target 3) and ascorbic acid (AA) cocatalyzed click reaction, which thus could be subsequently used for immobilization of two different photoactive nanomaterials labeled with single DNA to generate distinguishing dual-signal output for simultaneously sensitive detection of Pb2+ and Mg2+. Furthermore, the control variable method was used for detecting Cu2+ by altering the concentration of Cu2+ in the click reaction. Owing to the usage of the click reaction and target-converted signal amplifying strategy, the utilization rate of cycle output DNAs was largely increased, significantly improving the detection sensitivity of the proposed approach. As a result, low detection limits down to picomolar were acquired for the detection of Pb2+, Mg2+, and Cu2+, providing a versatile, efficient, and sensitive PEC method for multiple assays of various targets such as metal ions, small molecules, and tumor markers.

PtNPs as Scaffolds to Regulate Interenzyme Distance for Construction of Efficient Enzyme Cascade Amplification for Ultrasensitive Electrochemical Detection of MMP-2.

The high catalytic efficiency of enzyme cascade reaction mainly depends on optimal interenzyme distance regulated by the special scaffolds. In this work, the rigid PtNPs with different sizes were employed as scaffolds to regulate interenzyme distance for efficient enzyme cascade amplification to construct electrochemical biosensor for sensitive detection of matrix metalloproteinases-2 (MMP-2), which overcame the drawbacks of instable construction and sophisticated preparation induced by conventional scaffolds such as metal-organic frameworks (MOFs), DNA nanostructures. Here, cucurbit[7]uril functionalized PtNPs (CB[7]@PtNPs) was utilized to load ferrocene (Fc)-labeled horseradish peroxidase (HRP) and glucose oxidase (GOx) via host-guest interaction between Fc and CB[7], respectively, resulting in the formation of a stable three-dimensional netlike structure containing amounts of enzymes. Interestingly, the enzyme cascade reaction regulated by 10 nm PtNPs as scaffold showed highly catalytic efficiency. Meanwhile, the PtNPs could also serve as catalyst to accelerate the enzyme cascade reaction with further enhanced catalytic efficiency. As a result, the proposed biosensor exhibited excellent sensitivity with a wide linear range of 0.1 pg·mL-1 to 20 ng·mL-1 and a detection limit of 0.03 pg·mL-1 for MMP-2. Such a strategy opened a new avenue for adopting metal nanoparticles to regulate interenzyme distance for efficient enzyme cascade amplification, thus providing a universal and easy operating method for sensitively detecting various targets such as DNA, metal ion, and protein.

Self-Enhanced Ultrasensitive Photoelectrochemical Biosensor Based on Nanocapsule Packaging Both Donor-Acceptor-Type Photoactive Material and Its Sensitizer.

In this work, a self-enhanced ultrasensitive photoelectrochemical (PEC) biosensor was established based on a functionalized nanocapsule packaging both donor-acceptor-type photoactive material and its sensitizer. The functionalized nanocapsule with self-enhanced PEC responses was achieved first by packaging both the donor-acceptor-type photoactive material (poly{4,8-bis[5-(2-ethylhexyl)thiophen-2-yl]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl-alt-3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophene-4,6-diyl}, PTB7-Th) and its sensitizer (nano-C60, fullerene) in poly(ethylene glycol) (PEG) to form a nanocapsule, which significantly enhanced PEC signal and stability of the PEC biosensor. Moreover, a quadratic enzymes-assisted target recycling amplification strategy was introduced to the system for ultrasensitive determination. Compared with other established PEC biosensors, our proposed self-enhanced approach showed higher effectivity, accuracy, sensitivity, and convenience without any addition of coreactant or sensitizers into the testing electrolyte for photocurrent amplification and performed excellent analytical properties for microRNA estimation down to femtomole level with microRNA-141 as a model. Additionally, the proposed PEC biosensor was employed for estimation of microRNA in different cancer cells and pharmacodynamic evaluation in cancer cells. This self-enhanced PEC strategy has laid the foundation for fabrication of simple, effective, and ultrasensitive PEC diagnostic devices, leading to the possibility for early diagnosis, timely stage estimation, and accurate prognosis judgment of disease.

DNA Enzyme-Decorated DNA Nanoladders as Enhancer for Peptide Cleavage-Based Electrochemical Biosensor.

Herein, we developed a label-free electrochemical biosensor for sensitive detection of matrix metalloproteinase-7 (MMP-7) based on DNA enzyme-decorated DNA nanoladders as enhancer. A peptide and single-stranded DNA S1-modified platinum nanoparticles (P1-PtNPs-S1), which served as recognition nanoprobes, were first immobilized on electrode. When target MMP-7 specifically recognized and cleaved the peptide, the PtNPs-S1 bioconjugates were successfully released from electrode. The remaining S1 on electrode then hybridized with ssDNA1 (I1) and ssDNA2 (I2), which could synchronously trigger two hybridization chain reactions (HCRs), resulting in the in situ formation of DNA nanoladders. The desired DNA nanoladders not only were employed as ideal nanocarriers for enzyme loading, but also maintained its catalytic activity. With the help of hydrogen peroxide (H2O2), manganese porphyrin (MnPP) with peroxidase-like activity accelerated the 4-chloro-1-naphthol (4-CN) oxidation with generation of insoluble precipitation on electrode, causing a very low differential pulse voltammetry (DPV) signal for quantitative determination of MMP-7. Under optimal conditions, the developed biosensor exhibited a wide linear ranging from 0.2 pg/mL to 20 ng/mL, and the detection limit was 0.05 pg/mL. This work successfully realized the combination of DNA signal amplification technique with artificial mimetic enzyme-catalyzed precipitation reaction in peptide cleavage-based protein detection, offering a promising avenue for the detection of other proteases.

Luminescence-Functionalized Metal-Organic Frameworks Based on a Ruthenium(II) Complex: A Signal Amplification Strategy for Electrogenerated Chemiluminescence Immunosensors.

Novel luminescence-functionalized metal-organic frameworks (MOFs) with superior electrogenerated chemiluminescence (ECL) properties were synthesized based on zinc ions as the central ions and tris(4,4'-dicarboxylicacid-2,2'-bipyridyl)ruthenium(II) dichloride ([Ru(dcbpy)3](2+)) as the ligands. For potential applications, the synthesized MOFs were used to fabricate a "signal-on" ECL immunosensor for the detection of N-terminal pro-B-type natriuretic peptide (NT-proBNP). As expected, enhanced ECL signals were obtained through a simple fabrication strategy because luminescence-functionalized MOFs not only effectively increased the loading of [Ru(dcbpy)3](2+), but also served as a loading platform in the ECL immunosensor. Furthermore, the proposed ECL immunosensor had a wide linear range from 5 pg mL(-1) to 25 ng mL(-1) and a relatively low detection limit of 1.67 pg mL(-1) (signal/noise=3). The results indicated that luminescence-functionalized MOFs provided a novel amplification strategy in the construction of ECL immunosensors and might have great prospects for application in bioanalysis.

Novel electrochemical catalysis as signal amplified strategy for label-free detection of neuron-specific enolase.

A label-free electrochemical immunoassay for neuron-specific enolase (NSE), a kind of lung cancer marker, was developed in this work via novel electrochemical catalysis for signal amplification. The new amplified strategy was based on the electrochemical catalysis of nickel hexacyanoferrates nanoparticles (NiHCFNPs) in the presence of dopamine (DA). NiHCFNPs, which were assembled on the porous gold nanocrystals (AuNCs) modified glassy carbon electrode (GCE), could exhibit a distinct pair of redox peaks corresponding to anodic and cathodic reactions of hexacyanoferrate (II/III). Subsequently, gold nanoparticles functionalized graphene nanosheets (Au-Gra) were coated on the surface of NiHCFNPs/AuNCs film. Then an enhanced amount of neuron-specific enolase antibody (anti-NSE) could be loaded to obtain a sensitive immunosensor of anti-NSE/Au-Gra/NiHCFNPs/AuNCs/GCE due to the strong adsorption capacity and large specific surface area of Au-Gra. More importantly, the oxidation peak current can be enormously enhanced towards the electrocatalytic oxidation of DA based on NiHCFNPs, resulting in the further improvement of the immunosensor sensitivity. Under optimal conditions, the electrochemical immunosensor exhibited a linear range of 0.001-100 ng/mL with a detection limit of 0.3 pg/mL (S/N=3). Thus, the proposed immunosensor provides a rapid, simple, and sensitive immunoassay protocol for NSE detection, which may hold a promise for clinical diagnosis.

Highly conducting gold nanoparticles-graphene nanohybrid films for ultrasensitive detection of carcinoembryonic antigen.

A new label-free amperometric immunosensor was developed for detection of carcinoembryonic antigen (CEA) based on chitosan-ferrocene (CS-Fc) and nano-TiO(2) (CS-Fc+TiO(2)) complex film and gold nanoparticles-graphene (Au-Gra) nanohybrid. CS-Fc+TiO(2) composite membrane was first modified on a bare glass carbon electrode. Then Au-Gra nanohybrid was formed on the CS-Fc+TiO(2) membrane by self-assembly strategy. Next, further immobilization of anti-CEA was constructed according to the strong interaction between Au-Gra and the amido groups of anti-CEA. Since Au-Gra nanohybrid films provided a congenial microenvironment for the immobilization of biomolecules, the surface coverage of antibody protein could be enhanced and the sensitivity of the immunosensor has been improved. The good electronic conductive characteristic might be attributed to the synergistic effect of graphene nanosheets and Au NPs. The modified process was characterized by scanning electron microscope (SEM) and cyclic voltammetry (CV). Under optimized conditions, the resulting biosensor displayed good amperometric response to CEA with linear range from 0.01 to 80 ng/mL and a detection limit of 3.4 pg/mL (signal/noise=3). The results demonstrated that the immunosensor has advantages of high conduction, sensitivity, and long life time. This assay approach showed a great potential in clinical applications and detection of low level proteins.

Glucose oxidase and ferrocene labels immobilized at Au/TiO2 nanocomposites with high load amount and activity for sensitive immunoelectrochemical measurement of ProGRP biomarker.

Progastrin releasing-peptide (ProGRP) is a sensitive, specific, and reliable tumor marker with small cell lung cancer (SCLC), which may indicate an early tendency of cancer metastasis, causing high mortality rate. Thus, aiming for a more convenient assay system of SCLC, a novel immunoelectrochemical measurement for sensitive detection of ProGRP was developed in this work via Au nanoparticle/graphene modified immunosensor with ferrocene and glucose oxidase-multifunctionalized Au/TiO2 nanocomposites as a trace label. At first, Au nanoparticles (nano-Au) were attached on the TiO2 nanoparticles surface by using 3-aminopropyltriethoxy silane (APTES) as linkage reagent to obtain Au/TiO2 nanocomposites (nano-Au/TiO2). Next, glucose oxidase (GOD) and ferrocene labeled secondary antibodies (Fc-Ab2) were used to bind Au/TiO2 nanocomposites with high load amount and good biological activity, and because the increased surface area and biocompatibility of nano-Au/TiO2, the electrode can provide amplified signals. On the other hand, the nano-Au functionalized graphene sheets (GS) were used for the biosensor platform for increasing the surface area as well as improving the electronic transmission rate to capture a large amount of primary antibodies (Ab1). Then in presence of glucose, amplified signals can be obtained by an electrochemical sandwich immunoassay protocol. Based on the proposed immunosensor, the current is linear with the concentration of ProGRP being within a concentration range from 10.0 to 500 pg/mL with a limit of detection down to 3.0 pg/mL (S/N=3).

[Comparative study on GOD-trinder method for measuring glucose in serum with different benzene-original phenols].

Comparative studies were carried out on GOD-trinder method for measuring glucose in serum with four different kinds of benzene-original phenols-phenyl hydroxide, 2,4-dichlorophenol, 2,6-dichlorophenol and resorcinol. It is shown that when the three coloring systems-phenyl hydroxide, 2,4-dichlorophenol or resorcinol coupling with glucose oxidase-peroxidase-4-a minoantipyrine-hydrogen peroxide (GOD-POD-4-AA-H2O2) respectively were used for clinical assay of glucose in serum, the determination results showed no significant differences (P > 0.05). Compared with phenyl hydroxide, the coloring system of 2,4-dichlorophenol is better in the aspects of sensitivity, precision and accuracy; the resorcinol system has lower sensitivity with the advantage of faster detecting velocity, and larger linear range, and can be used for on-line rapid analysis of samples with more concentrated glucose in industry.

[Direct determination of ammonia in plasma with indophenol method].

A new method for direct determination of ammonia in plasmas with indophenol reagent is described. It is shown that using sodium citrate as anticoagulant in phosphate buffer within pH 10.5-11.2, indophenol reagent reacts sensitively with ammonia in the plasmas to form a stable blue compound with a maximum absorption at 630 nm with low interference. The apparent molor absorptivity is 2.48 x 10(4) L x mol(-1) cm(-1) , and the linear range 0-1500 micromol x L(-1) (r = 0.9999) with a detection limit of 1.7 micromol x L(-1). The relative standard deviation is 1.13% (n=11) and the recoveries are in the range of 93.6%-101.6% with an average recovery of 97. 0%. The proposed method has been applied to detect ammonia in the plasmas from 43 healthy persons and 97 patients who suffered from liver diseases with satisfactory results.

[The analysis of Gynostemma pentaphyllum (Thunb) Makino for Chinese crude drug by FTIR and FT-Raman].

The Gynostemma pentaphyllum is an important plant for Chinese crude drug. To qualitatively analyse the Gynostemma pentaphyllum (Thunb) Makino, FTIR and FT-Raman were used to identify the contents of it. The results show, that the trough of each absorption in the picture of FTIR spectrum and the characteristic wave crest of each dispersion in the picture of FT-Raman spectrum had parallelism at their position, their relation pairs with each other. This is useful for the further on-line quantitative analysis and quality control of the Gynostemma pentaphyllum (Thunb) Makino. This approach provide a quickly and accurately determination method of crude drug without extraction and separation.

[Determination of nitrotyrosine with catalytic spectrophotometry combining the substitution of nitroxyl by iodide].

The nitroxyl of nitrotyrosine can be substituted quantitatively by iodide when the nitroxyl is reduced to amino and then diazotized to diazonium. The iodide can be determined by catalytic spectrophotometric method with iodide-nitrous acid-arsenious acid system. Thus, a new catalytic spectrophotometric method combining the substitution of nitroxyl by iodide for the determination of nitrotyrosine has been established. The limit of detection is 0.002 mumol.L-1 and the linear range is 0.005-0.25 mumol.L-1. The method has been used for the determination of nitrotyrosine in the products of the reaction of tyrosine with peroxynitrite and the results are satisfactory.