镍（Ⅱ）—p—MPAQ络合物极谱吸附波研究

5-[(对-甲基苯基)偶氮]-8-氨基喹啉(p-MPAQ)的合成及其在光度和荧光分析中的应用已有报道,但对其电化学性质未作研究,本文研究了p-MPAQ的极谱行为,在pH6.8的醋酸铵缓冲溶液中,p-MPAQ在-0.55 V呈现一示波极谱波(P_1),当有Ni~(2+)存在时,在-0.93V处出现一新峰(P_2),加0.0011％Triton X-100后,P_2波高明显增加实验证实该波为络合物     

Detection of single nucleotide polymorphisms using electrospray ionization mass spectrometry: validation of a one-well assay and quantitative pooling studies

Single nucleotide polymorphisms (SNPs) are currently being mapped and databased at a remarkable pace, providing a viable means for understanding disease susceptibility, differential drug response and human evolution. Consequently, there is an increasing demand for SNP genotyping technologies that are simple, rapid, cost effective and readily amenable to automation for high-throughput analyses. In this study, we improved the Survivor Assay, a SNP detection method based on electrospray ionization mass spectrometry (ESI-MS), with several developments. One improvement is the development of a one-well assay, requiring no off-line purification of the polymerase chain reaction product, achieved by simple addition of reagent solution into a single well. Another is the on-line separation of magnesium and dideoxynucleotides using an in-house made monolithic metal chelating column, eliminating any off-line sample preparation prior to mass spectrometric analysis. Here the Survivor Assay is extended from a proof-of-principle concept to a validated method by genotyping six SNPs from five different regions of human genomic DNA in 55 individual samples with 100% accuracy. This improved Survivor Assay eliminates the tedious and time-consuming steps of sample preparation, minimizes sample handing and offers a high-throughput analysis of SNPs by ESI-MS. The current combined preparation and analysis time is 2 min per sample. The simplicity of this method has potential for full automation and parallel chromatography and, thus, reduced analysis time. In addition, we have adapted the Survivor Assay for quantitative SNP analysis in pooled DNA samples. The capabilities and sensitivity of this approach were evaluated. We demonstrate that an allele occurring at a frequency of 2% can consistently be quantitated.     

端基含葡氨糖衍生物的聚乳酸的合成与表征

端基含葡氨糖衍生物的聚乳酸的合成与表征张国栋冯新德（北京大学高分子科学与工程系北京１００８７１）顾忠伟（国家计生委科研所药化室北京１０００８１）关键词壳多糖，聚乳酸，生物医用材料，化学修饰自从发现高分子量聚乳酸在人体内能够降解，并把这类材料引入...     

Development of a competitive liposome-based lateral flow assay for the rapid detection of the allergenic peanut protein Ara h1

A competitive lateral flow assay for detecting the major peanut allergen, Ara h1, has been developed. The detector reagents are Ara h1-tagged liposomes, and the capture reagents are anti-Ara h1 polyclonal antibodies. Two types of rabbit polyclonal antibodies were raised either against the entire Ara h1 molecules (anti-Ara h1 Ab) or against an immunodominant epitope on Ara h1 (anti-peptide Ab). All of them reacted specifically with Ara h1 in Western Blot against crude peanut proteins. Moreover, the anti-Ara h1 Ab was chosen for this assay development because of its highest immunoactivity to Ara h1-tagged liposomes in the lateral flow assay. The calculated limit of detection (LOD) of this assay is 0.45 g mL^–1 of Ara h1 with a dynamic range between 0.1 and 10 g mL^–1 of Ara h1 in buffer. Additionally, the visually determined detection range is from 1 to 10 g mL^–1 of Ara h1 in buffer. Results using this assay can be obtained within 30 min without the need of sophisticated equipment or techniques; therefore, this lateral flow assay has the potential to be a cost-effective, fast, simple, and sensitive method for on-site screening of peanut allergens.     

Fast and highly selective determination of cyanide with 2,2-dihydroxy-1,3-indanedione

A very simple, accurate, fast, selective and sensitive assay of cyanide based on its reaction with 2,2-dihydroxy-l,3-indanedione at basic pH is proposed. As little as 0.01 μg ml⁻¹ of cyanide can be determined. The molar absorptivity may reach 5.1–8.0×10⁴ l mol⁻¹ cm⁻¹ depending on the reaction conditions. Thus, 1 ml of sample solution is mixed with 500 μl of 5 mg ml⁻¹ solution of 2,2-dihydroxy-1,3-indanedione monohydrate in 2% sodium carbonate. The absorbance of the purple color is measured at 510 nm in 1-cm glass cuvettes, 10–15 min after mixing the reagents. The procedure could also be used to identify free CN⁻ in natural waters and hydrocyanic acid in the environment.     

Determination of Human Alpha-Fetoprotein (AFP) by Solid Substrate Room Temperature Phosphorescence Enzyme-Linked Immune Response Using Luminescent Nanoparticles

Luminescent nanoparticles of silicon dioxide (SiO₂) containing fluorescein isothiocyanate (FITC) with a particle size of 20 nm were synthesized using the Sol–Gel method (abbreviated FITC–SiO₂). FITC–SiO₂ nanoparticles whose surfaces are modified (FITC–SiO₂–S–CH₂COOH) can emit strong and stable solid substrate room temperature phosphorescence (SS-RTP) on acetyl cellulose membranes. When the original color-producing agent (R) in the enzyme-linked immunosorbent assay (ELISA) kits for determination of alpha-fetoprotein (AFP) was substituted with (FITC–SiO₂–S–CH₂COOH), the system maintained good FITC–SiO₂ phosphorescence properties. Furthermore, the phosphorescence intensity enhanced markedly after the ELISA reaction. The relationship between the phosphorescence intensity and the content of AFP obeyed Beer’s law. Based on the facts stated above, a new method for the determination of human AFP by SS-RTP-ELISA (using the luminescent nanoparticle as marker) was established. The linear range of this method is 0.040–16.0 pg of human AFP per spot (sample volume: 0.40 μL spot⁻¹, corresponding concentration: 0.10–40.0 ng mL⁻¹). The regression equation of the working curve is ΔIp = −6.289+18.075 m_AFP (pg spot⁻¹) (r = 0.9960, n = 6). The detection limit (LD) of this method calculated by 3 S_b/k is 6.7 fg spot⁻¹ (corresponding concentration: 17 ng L⁻¹). Compared to the ELISA method using a traditional color-producing agent, the new method exhibited a 34.8 times higher sensitivity and a wider linear range. The method has been successfully applied to the determination of human AFP in serum.     

Novel functional activities of anti-dna autoantibodies from sera of patients with lymphoproliferative and autoimmune diseases

DNA-hydrolyzing activity of IgG autoantibodies from sera of patients with various types of lymphoproliferative diseases was investigated. The association of DNA-hydrolyzing activity with the antibody (Ab) fraction has been proved by newly developed affinity-capture assay. Study of abzyme incidence in blood tumors and systemic lupus erythematosis (SLE) revealed linkage of anti-DNA Ab catalysts to mature B-cell tumors, and increased probability of DNA-abzymes formation on the background of autoimmune manifestations. These data suggest possible similarity between mechanisms of abzyme formation in SLE and B-cell lymphomas. A new mechanism of formation of DNA-specific catalytic Abs has been proposed based on the increased crossreactivity of polyclonal DNA-abzymes to DNA-depleted nuclear matrix proteins. The possibility of the abzyme production as Ab to the energetically destabilized ground state of the antigen has been discussed. Preliminary results were obtained that indicate the complement-independent cytotoxicity of anti-DNA autoantibodies isolated from blood of patients with SLE and chronic lymphocytic leukemia.     

KINETICS OF IRREVERSIBLE MODIFICATION OF ENZYME ACTIVITY IN A SYSTEM OF COUPLED ENZYME ASSAY (Ⅱ)——BOTH PRIMARY AND AUXILIARY ENZYMES MODIFIED BY REAGENT Y

Following the previous paperr, we examined the kinetics of the irreversible modification of enzyme activity in coupled assay when the modifier reacted with both primary and auxiliary enzymes. It was shown that Tsou's kinetic method can also be used in the present situation in some conditions.     

Oral malodor,assessed by closed-loop,gas chromatography,and ion-trap technology

A method is described for the analysis of volatile organic compounds in saliva and tongue coating samples. The techniue is based on an off-line preconcentration step by means of a closed-loop trapping system followed by gas chromatography-ion trap detection. With the closed-loop technique, the volatile organic compounds(VOCs) are released from the matrix and trapped on an adsorbent without interference of water. The VOCs are released from the adsorbent into the gas chromatograph by thermdesorption. After separation, identification of the compounds is performed by ion trap technology. By this technique 82 compounds could be demonstrated in saliva and tongue coating samples. The technique is also used to demonstrate the formation of volatile bacterial fermentation compounds when a protein substrate is added to tongue coating samples. It is considered a very promising tool in further research on oral malodor.     

Comparative evaluation of Fe(III) reducing power-based antioxidant capacity assays in the presence of phenanthroline, batho-phenanthroline, tripyridyltriazine (FRAP), and ferricyanide reagents

The chemical diversity of antioxidants in complex matrices such as plant extracts makes it difficult to separate and quantify antioxidants from these solutions. Therefore it is desirable to establish methods that can measure the total antioxidant capacity (TAC) levels directly from plant extracts. Iron(III)-based TAC assays, especially the most widely used FRAP (ferric-reducing antioxidant power), play an important role in this regard. However, many problems have been reported in the application of the FRAP assay, the most serious one being the incomplete oxidation of a number of antioxidants during the time protocol of the assay. Thus, six different ferric ion-based total antioxidant capacity (TAC) assays have been comparatively tested, modified, and improved so as to obtain more sensitive and precise results for complex mixtures, namely: 1,10-phenanthroline (o-phen) method (with incubation), batho-phenanthroline method (with incubation), original FRAP method, modified FRAP method (with incubation), original ferricyanide method, and modified ferricyanide method (with incubation). Two new assays in this regard (i.e., o-phen and batho-phen) have been established, and the existing assays (FRAP and ferricyanide) have been modified so as to let the oxidation reactions of antioxidants reach completion. The molar absorptivity for a variety of antioxidants was highest for modified FRAP, batho-phen, and original FRAP methods. The absorption maximum wavelength shifted batochromically to a higher extent for modified ferricyanide, FRAP, and batho-phen procedures, decreasing the possibility of interferences due to organics absorbing in the near-UV range of the visible spectrum where most antioxidant assays are performed. The linear concentration ranges were shown to be further extended and linear correlation coefficients improved with respect to the most widely used ferric-based assay, FRAP. Of the six assays tested and developed, only the modified ferricyanide procedure gave high intercept values and low addivitity of TAC values of constituents in complex mixtures, requiring further attention of method optimization. Thus, it was shown that the most widely used FRAP could be effectively modified, and o-phen, batho-phen, and ferricyanide methods constitute cheaper alternatives to FRAP under certain conditions, with partly improved molar absorptivity (and thus sensitivity) for antioxidants, lower intercept values (and higher precision), broader linear range (and higher flexibility), and better additivity of TAC values of antioxidant constituents in mixtures.