GoldMag nanocomposite-functionalized graphene sensing platform for one-step electrochemical immunoassay of alpha-fetoprotein

A new flow-through electrochemical immunosensor was designed for sensitive detection of alpha-fetoprotein (AFP) in human serum by using nanogold-functionalized magnetic graphene nanosheets as immunosensing probes. Initially, amino functionalized magnetic beads were covalently immobilized on the surface of graphene oxide nanosheets (MGPs), then nanogold particles were adsorbed on the amino groups of the MGPs to construct GoldMag nanocomposites functionalized graphene nanosheets (GMGPs), and then horseradish peroxidase-anti-AFP conjugates (HRP-anti-AFP) were assembled onto the surface of nanogold particles (bio-GMGP). With the aid of an external magnet, the formed bio-GMGPs were attached onto the base electrode in the flow system. With a non-competitive immunoassay format, the injected sample containing AFP antigens was produced transparent immunoaffinity reaction with the immobilized HRP-anti-AFP on the bio-GMGPs. The formed immunocomplex inhibited partly the active center of HRP, and decreased the labeled HRP toward the reduction of H(2)O(2). The performance and factors influencing the performance of the immunosensor were investigated in detail. Under optimal conditions, the electrochemical immunosensor displayed a wide working range of 0.01-200 ng mL(-1) with a low detection limit (LOD) of 1.0 pg mL(-1) AFP (at 3s(B)). Intra- and inter-assay coefficients of variation (CV) were below 10%. In addition, the methodology was validated with real serum samples, receiving a good correlation with the results obtained from commercially available electrochemiluminescence automated analyzer.     

A sensitive and selective immuno‐nanogold resonance‐scattering spectral method for the determination of trace penicillin G

A sensitive and selective immuno‐nanogold resonance scattering spectral assay was developed for the determination of trace hapten penicillin G, based on the resonance scattering (RS) effect of the nanogold at 560 nm, and the nanogold‐labelled immunoreaction took place in pH 5.4 phosphate citric acid buffer solutions and in the presence of polythylene glycol (PEG). The nanogold‐labelled immunocomplex formed more and more with addition of penicillin G. The enhanced RS intensity at 560 nm ΔI_RS was linear to the penicillin G concentration in the range 7.5–1700 ng/mL, with a detection limit of 0.78 ng/mL. The results indicate that the immunonanogold‐labelled RS spectral assay has a high specificity and sensitivity for quantitative determination of penicillin G in raw milk samples. Copyright © 2008 John Wiley & Sons, Ltd.     

Estradiol and testosterone concentrations increase with fasting in weaned pups of the northern elephant seal (Mirounga angustirostris)

Although neonatal development is generally associated with increased levels of circulating testosterone (T) and estradiol (E2), food deprivation may inhibit steroidogenesis. Therefore, these potentially conflicting stimuli were examined in fasting weaned northern elephant seal (Mirounga angustirostris) pups by measuring serum concentrations of T, E2, progesterone (P4), and luteinizing hormone (LH) by either radioimmunoassay (P4, LH) or enzymeimmunoassay (T, E2). Blood samples were obtained from 20 male and 20 female pups at both early (<1 wk postweaning) and late (6-8 wk postweaning) periods during their natural postweaning fast. T in males (early: 2.9 +/- 0.4 ng/mL; late: 16 +/- 2 ng/mL; P < 0.0001) and E2 in females (early: 42 +/- 6 pg/mL; late: 67 +/- 5 pg/mL; P < 0.01) increased between the two measurement periods, while P4 (early: 2.5 +/- 0.3 ng/mL; late: 2.1 +/- 0.3 ng/mL; P > 0.05) did not. LH increased (early: 46 +/- 4 pg/mL; late: 65 +/- 6 pg/mL; P < 0.05) in males but not in females (early: 69 +/- 9 pg/mL; late: 65 +/- 6 pg/mL; P > 0.05). Increases in LH and T suggest that LH may stimulate T secretion. Alternatively, relatively low concentrations of LH in both males and females may reflect negative feedback inhibition imposed by elevated T and E2 concentrations. Despite the inherent postweaning fast, concentrations of T and E2 increased, suggesting that they may be critical for the continued development of pups. Therefore, compensatory mechanisms may exist that alleviate the fasting-induced inhibition of gonadal steroidogenesis during neonatal development in elephant seal pups.     

A disposable bio-nano-chip using agarose beads for high performance immunoassays

This article reports on the fabrication of a disposable bio-nano-chip (BNC), a microfluidic device composed of polydimethylsiloxane (PDMS) and thiolene-based optical epoxy which is both cost-effective and suitable for high performance immunoassays. A novel room temperature (RT) bonding technique was utilized so as to achieve irreversible covalent bonding between PDMS and thiolene-based epoxy layers, while at the same time being compatible with the insertion of agarose bead sensors, selectively arranged in an array of pyramidal microcavities replicated in the thiolene thin film layer. In the sealed device, the bead-supporting epoxy film is sandwiched between two PDMS layers comprising of fluidic injection and drain channels. The agarose bead sensors used in the device are sensitized with anti-C-reactive protein (CRP) antibody, and a fluorescent sandwich-type immunoassay was run to characterize the performance of this device. Computational fluid dynamics (CFD) was used based on the device specifications to model the bead penetration. Experimental data revealed analyte penetration of the immunocomplex to 100 μm into the 280 μm diameter agarose beads, which correlated well with the simulation. A dose-response curve was obtained and the linear dynamic range of the assay was established over 1 ng/mL to 50 ng/mL with a limit of detection less than 1 ng/mL.     

Should Food Intake and Circadian Rhythm be Considered When Measuring Serum Calcitonin Level?

ObjectiveTo investigate the relationship between both food intake and circadian rhythmicity and serum calcitonin in the same individuals.MethodsEighteen healthy subjects, 10 males and 8females, aged 22 to 24 years, were recruited. Serum calcitonin level was measured three times: at 0800 after a 9-hour overnight fast, at 0900 postprandially, and at 1700 after another 9-hour fast. The same protocol was repeated once.ResultsThe mean calcitonin levels (at 0800) were 3.92 pg/mL (SD, 2.5 pg/mL) on Day 1 and 3.52 pg/mL (SD, 2.1 pg/mL) on Day 2. Mean postprandial calcitonin (at 0900) was 9.46 pg/mL (SD, 8.6 pg/mL) on Day 1 and 9.91 pg/mL (SD, 6.9 pg/mL) on Day 2. Mean fasting calcitonin in the evening (at 1700) was 6.74 pg/mL (SD, 4.73 pg/mL) on Day 1 and 6.49 pg/mL (SD, 3.57 pg/mL) on Day 2. There was no significant difference in the mean calcitonin level on days 1 and 2 for any of the three time points examined. Statistically significant differences were found between postprandial and evening calcitonin levels and the fasting levels on Day 1 (P = .018 and .015, respectively) and Day 2 (P = .001 and .0009, respectively).ConclusionThese results suggest that serum calcitonin level is significantly influenced by food intake in healthy young subjects and reveal a circadian rhythm, with increased calcitonin level during the afternoon. The timing of blood sampling relative to meals should be integrated into clinical practice and research settings involving serum calcitonin measurements. (Endocr Pract. 2013; 19:620-626)     

Circulating angiogenic cytokines in multiple myeloma and related disorders

We investigated the serum concentrations of selected angiogenic cytokines including: vascular endothelial growth factor (VEGF), hepatocyte growth factor (HGF), transforming growth factor beta 1 (TGF-beta1) and basic fibroblast growth factor (bFGF) in 162 patients with multiple myeloma (MM), 5 patients with Waldenstr m's macroglobulinaemia (WM), and 31 healthy controls. Among the MM patients there were 2 cases of primary plasma cell leukemia (PCL) and one case of extramedullary plasmacytoma. The levels of measured cytokines were correlated with the phase and stage of the disease as well as the most important clinical and laboratory parameters associated with disease activity (haemoglobin, creatinine, albumins, calcium, M-component, CRP,beta2m, LDH and bone involvement). We have found correlations between serum levels of angiogenic cytokines and some parameters depicting the disease activity and advancement. The serum level of VEGF in MM patients (median 244.5 pg/mL) correlated with serum concentrations of beta-2-microglobulin (beta2m) greater than 2.5 mg/L (p = 0.0005) and abnormal values of lactate dehydrogenase (> 425 U/L, median 329.0 pg/mL and < 210 U/L, median 426.6 pg/mL, p = 0.004 and p = 0.04 respectively). MM patients in stage III had higher serum levels of HGF (median 1 411.3 pg/mL) than those in stage I (median 1 219 pg/mL) (p = 0.01) according to Durie and Salmon staging, and those in phase I (at diagnosis) (median 1 555.6 pg/mL) and phase III (in progression) (median 1 309.7 pg/mL) had higher levels than those in phase II (plateau phase) (median 1 047.9 pg/mL) (p = 0.002 and p = 0.02 respectively). Significantly elevated values of HGF were found in MM patients with anaemia (median 1 962.0 pg/mL) and hypercalcaemia (median 2 085.6 pg/mL) (p = 0.00001 and 0.04 respectively). TGF-beta1 (median 33.9 ng/mL) correlated positively with highbeta2m values (> 2.5 mg/L) (p = 0.04) and was significantly higher in phase I (median 40.1 ng/mL) than in phase II (median 30.9 ng/mL) (p = 0.03) of the disease. The concentration of bFGF was significantly higher in stage III of MM (median 3.1 pg/mL) than in stage I (median 1.2 pg/mL) (p = 0.04). We found that the survival probability was statistically higher for newly diagnosed MM patients with a concentration of VEGF lower than the median value for this cytokine. The concentrations of the cytokines analyzed in patients with Waldenstr m's macroglobulinaemia (WM), primary plasma cell leukaemia (PCL) and non-secretory (NS) myeloma were not distinguishable from those found in MM patients. We also studied the relationship between the levels of cytokines analyzed and found positive correlations between bFGF and TGF-beta1 (rh? = 0.183, p < 0.02), as well as VEGF and TGF-beta 1 (rh? = 0.537, p < 0.001) and VEGF and bFGF (rh? = 0.197, p < 0.02). In conclusion, our data indicate a strong relationship between angiogenic cytokine serum levels and clinical course as well as selected laboratory parameters of patients with MM.     

Microchip fluorescence-enhanced immunoaasay for simultaneous quantification of multiple tumor markers

A microchip fluorescence-enhanced immunoassay method was developed for simultaneous detection of carcinoma antigen 125 (CA125) and carbohydrate antigen 15-3 (CA15-3). In this method, CA125 and CA15-3 react with excess amount of fluorescein isothiocyanate (FITC)-labeled monoclonal antibodies (Ab(*)) of CA125 and CA15-3 to form CA125-Ab(125)(*) and CA15-3-Ab(15-3)(*) complexes. Microchip electrophoresis (MCE) separation of free Ab(125)(*), Ab(15-3)(*), and CA125-Ab(125)(*), CA15-3-Ab(15-3)(*) complexes were then performed. The separated species were sensitively detected by laser-induced fluorescence detection (LIF). CA125 and CA15-3 were quantified simultaneously by measuring the fluorescence intensity of CA125-Ab(125)(*) and CA15-3-Ab(15-3)(*) complexes, respectively. Under the optimum conditions, the limits of detection were 0.23 U/mL for CA125 and 0.09 U/mL for CA15-3. The present MCE-LIF method was applied to the determination of CA125 and CA15-3 in serum from healthy subjects and cancer patients. The levels of CA125 and CA15-3 in these sera samples were found to be in the ranges of 15.6-36.1 U/mL and 13.8-28.4 U/mL for healthy subjects, and 192.5-368.3 U/mL and 63.3-198.4 U/mL for cancer patients.     

Chemiluminescence sandwich enzyme immunoassay for determination of human granulocyte colony stimulating factor (G-CSF)

A chemiluminescence sandwich enzyme immunoassay, using a glucose oxidase (GO) label, was developed for detecting attomole amounts of human granulocyte colony stimulating factor (G-CSF). Purified goat F(ab′)₂ immobilized on a bead and purified goat Fab′ labelled with GO were selected in combination with a chemiluminescent detection system comprising luminol and ferricyanide. The detection limits for G-CSF were 4amol/assay (1 pg/mL) in buffer solution and 10 amol/assay (2.5 pg/mL) in human serum. Coefficients of variation within assay and between assay ranged from 5.5% to 7.8% and from 3.4% to 16.0%, respectively. The G-CSF content of serum from normal healthy individuals was measurable using this method. G-CSF in 24 normal human sera showed a mean value of 19.3 pg/mL and ranged from 3.6 to 83.0 pg/mL.     

血必净干预对慢性阻塞性肺疾病大鼠体内炎症因子的影响

目的：通过观察血必净干预对慢性阻塞性肺疾病（COPD）大鼠体内炎症因子的影响,探讨血必净治疗COPD的机制。方法：36只Wistar雄性大鼠随机分为对照组、COPD模型组（简称模型组）、血必净干预组（简称干预组）,每组12只。采用香烟烟雾暴露加气管内滴注脂多糖法建立COPD大鼠模型。造模时间共30天,其中干预组在后15天给予血必净4ml／Kg体重尾静脉注射。分别测定各组肺功能,肺组织病理学变化,血清及肺泡灌洗液中肿瘤坏死因子（TNF-α）、白介素-6（IL-6）、白介素-8（IL-8）浓度。结果：模型组大鼠FEV0．3／FVC[（57．8±5．6）％]和动态肺顺应性（Cydn）[（0．098＋0．006）cmH20·mL^-1·s^-1,lcmH20=0．098kPa]均明显低于对照组[（81．4±3．1）％和（0．195±0．012）cmH20·mL^-1·S^-1],而干预组大鼠[（67．2±3．2）％和（0．142±0．024）cmH20·mL‘S‘。]则较模型组有显著提高,差异均具有统计学意义（t值分别为-13．940、-15．165、-5．552、-6．927,均P〈0．01）;模型组大鼠平均气道阻力（RI）[（0．802±0．070）mL／cmH20]明显高于对照组[（0．224±0．069）mL／cmH20],而干预组[（0．475±0．050）mL／cmH20]则较模型组有明显下降,差异均具有统计学意义（t值分别为-22．389、-12．658,均P〈0．01）;模型组大鼠血清和肺泡灌洗液中TNF-α、IL-6、IL-8浓度[（27．8±7．4）pg／mL和（340．0±79．6）pg／mL、（209．9±82．1）pg／mL和（337．3±96．4）pg／mL、（37．7±11．4）pg／mL和（69．6±18．9）pg／mL]均显著高于对照组,差异均具有统计学意义（t值分别为-12．466、-19．648、-11．749、-16．364、12．550、14．834,均P〈0．01）,而干预组大鼠[（9．6±5．6）pg／mL和（45．6±22．9）pg／mL、（36．3±17．9）pg／mL和（42．9±20．5）pg／mL、（10．3±5．6）pg／mL和（15．7±8．0）pg／mN．~4较模型组有显著降低,差异均具有统计学意义（t值分别为-9．367、-17．390、-10．106、-14．631、10．475、12．772,均P〈0．01）。结论：COPD大鼠血清及肺泡灌洗液中炎症因子TNF-α、IL-6、IL-8的浓度均显著增高,血必净干预能显著下调上述关键致炎因子的表达,并与其临床症状、肺功能、病理学改变相印证。因此,我们推测：血必净可能通过下调COPD炎症时TNF-α、IL-6、IL-8等关键致炎因子的表达,进一步抑制气道炎症的级联效应来发挥其强大的抗炎作用。     

[AuCl4]− and Fe3+/[Fe(CN)6]3− ions-derivated immunosensing interface for electrochemical immunoassay of carcinoembryonic antigen in human serum

[AuCl₄]⁻ was initially deposited by electrochemical reduction on a glassy carbon electrode (GCE) to form porous nanogold layer, then prussian blue (PB) was electrodeposited onto the as-prepared nanogold layer, and then secondary nanogold particles were fabricated again on the PB surface by electrochemical reduction for the immobilization of anti-CEA antibodies. The presence of double-layer porous gold nanoparticles enhanced the immobilized amount of biomolecules, and improved the sensitivity of the immunoassay. PB, as a good redox probe, was facile to electrochemical analysis and measurement. Under optimal conditions, the developed immunoassay exhibited dynamic range from 3.0 to 80.0 ng/mL with a detection limit of 0.9 ng/mL CEA (S/N = 3). Moreover, the selectivity, reproducibility and stability of the immunosensor were acceptable.     

Conductometric immunoassay for interleukin-6 in human serum based on organic/inorganic hybrid membrane-functionalized interface

Various sensor-based immunoassay methods have been extensively developed for the detection of interleukin-6 (IL6), but most often exhibit low detection signals and low detection sensitivity, and are unsuitable for routine use. The aim of this work is to develop a simple and sensitive conductometric immunoassay for IL6 in human serum by using an organic/inorganic hybrid membrane-functionalized interface. Initially, thionine-bound 3,4,9,10-perylenetetracarboxylic acid was doped into colloidal alumina, then nanogold particles were immobilized onto the thionine surface, and then horseradish peroxidase-labeled anti-IL6 antibodies were conjugated on the nanogold surface. The organic/inorganic hybrid membrane provides a good microenvironment for the immobilization of biomolecules, enhanced the surface coverage of protein, and improved the sensitivity of the immunosensor. The performance and factors influencing the performance of the immunosensor were evaluated. The detection is based on the change in local conductivity before and after the antigen-antibody interaction in 0.02 M phosphate buffer solution (pH 6.8) containing 50 μM H₂O₂, 0.01 M KI and 0.15 M NaC1. Under optimal conditions, the proposed immunosensor exhibited a wide linear range from 25 to 400 pg/ml towards IL6 with a relatively low detection limit of 5 pg/ml (S/N = 3). The stability, reproducibility and precision of the immunosensor were acceptable. 37 serum specimens were assayed by the developed immunosensor and standard enzyme-linked immunosorbent assay, respectively, and the results obtained were almost consistent. More importantly, the detection methodology provides a promising approach for other proteins or biosecuritys.     

Fabrication of protein microarrays using the electrospray deposition (ESD) method: Application of microfluidic chips in immunoassay

In this study, antibody-based protein microarrays for high-throughput immunoassay were fabricated on an aldehydemodified indium-tin oxide glass plate using the electrospray deposition (ESD) method and their characteristics were evaluated immunochemically. The microarrays were also integrated into microfluidic chips with a polydimethylsiloxane (PDMS) micro-channel to detect human cytokines, which were quantitatively analyzed with a high resolution chargecoupled device. Simultaneous detection of various antigens was performed using the microarrays with considerable sensitivity (ca. 100 pg/mL). The results of this study indicate that microfluidic chip comprising a protein microarray formed by the ESD method and a PDMS micro-channel could be easy to handle, and offers high-throughput detection of molecular biomarkers.     

In vivo microdialysis sampling of cytokines produced in mice given bacterial lipopolysaccharide

Cytokines are proteins that mediate communication between cells of the immune system as well as certain other non-immune host cells. These proteins are produced by many cell types and they mediate immune and inflammatory responses. However, the direct site analysis of these critical proteins is hampered by the lack of site-specific tools available for such direct measurements. In this study, both in vitro and in vivo microdialysis sampling of different cytokines (tumor necrosis factor-alpha [TNF-alpha], interferon-gamma [IFN-gamma], interleukin-6 [IL-6], IL-12p70, and macrophage chemoattractant protein-1 [MCP-1]) was performed. A mouse model of bacterial lipopolysaccharide (LPS) administration and response pattern was used for in vivo studies. Three cytokines, TNF-alpha, IL-6, and MCP-1 were quantified in the serum from mice given LPS. In vivo studies demonstrated the ability to monitor increasing levels of these cytokines (TNF-alpha, IL-6, and MCP-1) via microdialysis probes placed in the peritoneal cavity of mice given LPS. All three cytokines were quantified simultaneously in 15 muL of dialysate using a multiplexed bead-based immunoassay for flow cytometry. The detected dialysate cytokine concentrations varied between 200 pg/mL and 1500 pg/mL for TNF-alpha, between 600 pg/mL and 3000 pg/mL for MCP-1, and between 2700 pg/mL and more than 5000 pg/mL for IL-6. The detected serum cytokine concentrations ranged from 5700 pg/mL to 35,000 pg/mL for TNF-alpha, from 40,000 pg/mL to 65,000 pg/mL for MCP-1, and greater than than 100,000 pg/mL for IL-6. This work demonstrates that microdialysis sampling can be used in vivo to collect temporal profiles of cytokine production.     

Microfluidic electrochemical immunoarray for ultrasensitive detection of two cancer biomarker proteins in serum

A microfluidic electrochemical immunoassay system for multiplexed detection of protein cancer biomarkers was fabricated using a molded polydimethylsiloxane channel and routine machined parts interfaced with a pump and sample injector. Using off-line capture of analytes by heavily-enzyme-labeled 1 μm superparamagnetic particle (MP)-antibody bioconjugates and capture antibodies attached to an 8-electrode measuring chip, simultaneous detection of cancer biomarker proteins prostate specific antigen (PSA) and interleukin-6 (IL-6) in serum was achieved at sub-pg mL?1 levels. MPs were conjugated with ～90,000 antibodies and ～200,000 horseradish peroxidase (HRP) labels to provide efficient off-line capture and high sensitivity. Measuring electrodes feature a layer of 5 nm glutathione-decorated gold nanoparticles to attach antibodies that capture MP-analyte bioconjugates. Detection limits of 0.23 pg mL?1 for PSA and 0.30 pg mL?1 for IL-6 were obtained in diluted serum mixtures. PSA and IL-6 biomarkers were measured in serum of prostate cancer patients in total assay time 1.15 h and sensor array results gave excellent correlation with standard enzyme-linked immunosorbent assays (ELISA). These microfluidic immunosensors employing nanostructured surfaces and off-line analyte capture with heavily labeled paramagnetic particles hold great promise for accurate, sensitive multiplexed detection of diagnostic cancer biomarkers.     

Relationship between peripheral blood dendritic cells and cytokines involved in the pathogenesis of systemic lupus erythematosus

Recent studies indicate that dendritic cells (DC) and several cytokines are implicated in the induction of autoimmune diseases. In this study we investigated the relationship between the total number of DC (tDC), and their plasmacytoid (pDC) and myeloid (mDC) subpopulations, with serum concentrations of interferons (IFN-alpha and IFN-gamma) and selected cytokines (TNF-alpha, IL-4, IL-6), in patients with systemic lupus erythematosus (SLE) and healthy persons. Subpopulations of DC were determined by the following antigen expression profiles: BDCA-1+\CD11c+\HLA-DR+ (for mDC) and BDCA-2 +\CD123+\HLA-DR+ (for pDC), using flow cytometry. Serum levels of interferons and cytokines were assessed by an enzyme-linked immunosorbent assay (ELISA). The study was performed in 36 SLE patients and 19 healthy volunteers. The mean number of tDC was lower in SLE patients (13.9 +/- 6.4\microL) than in healthy persons (24.1 +/- 12.6\microL) (P < 0.001). The number of pDC was also significantly lower in SLE (6.6 +/- 3.6\microL) than in the control group (12.0 +/- 8.3\microL) (P < 0.02). Moreover, the mean pDC count was lower in active than in inactive disease (5.5 +/- 3.6\microL vs 7.6 +/- 3.4\microL; P < 0.04). The mean serum levels of IFN-alpha and IFN-gamma were significantly higher in SLE patients (63.8 pg\mL and 6.6 pg\mL, respectively) than in the control group (2.7 pg\mL and 0.5 pg\mL, respectively) (P < 0.008 and P < 0.001, respectively). Serum levels of TNF-alpha and IL-6 were also higher in SLE patients (mean 7.3 pg\mL and 18.4 pg\mL, respectively) than in healthy controls (4.2 pg\mL and 0.5 pg\mL, respectively) (P < 0.02 and P < 0.001, respectively). The mean serum IL-4 concentrations were similar in SLE and healthy persons (0.2 pg\mL and 0.31 pg\mL, respectively; P -/+ 0.119). A negative correlation was found between pDC number and the serum level of IFN-alpha (rho -/+ -- 0.386, P -/+ 0.02) and between mDC and IFN-gamma (rho -/+ -- 0.377, P -/+ 0.024). In conclusion, the correlation between peripheral blood DC subsets and serum levels of IFN-alpha and IFN-gamma suggests a possible relationship between these cytokines in the pathogenesis of SLE.     

The determination of 2beta-(3-hydroxypropoxy)-1alpha,25-dihydroxy vitamin D3 (ED-71) in human serum by high-performance liquid chromatography-electrospray tandem mass spectrometry

A liquid chromatography-electrospray ionization tandem mass spectrometric (LC/ESI-MS/MS) method for the determination of 2beta-(3-hydroxypropoxy)-1alpha,25-dihydroxy vitamin D3 (ED-71) in human serum has been developed. ED-71 in human serum was extracted using two solid-phase extraction steps on Bond Elut C18 and NH2 cartridge. The separation of ED-71 and preED-71 isomer was attained by LC using 2 mmol/L ammonium acetate-methanol (15:85, v/v) as a mobile phase on a Symmetry C18 column (5 microm, 150 mm x 2.1mm i.d.). ESI-MS/MS analysis was operated using selected reaction monitoring (SRM) in positive ion mode. The method achieved a lower limit of quantitation of 25 pg/mL. The calibration curve (25-3200 pg/mL) gave acceptable linearity (r>0.9964). Intra-assay precision ranged from 2.3 to 9.7%. Inter-assay precision ranged from 1.0 to 3.4%. The accuracy was within 90.8-107.0%. This highly sensitive and reproducible method is able to determine only biologically active ED-71 by separating it from preED-71, which is considered to be applicable for the determination of serum samples from pharmacokinetic studies in human.     

Electrochemiluminescence of CdSe quantum dots for immunosensing of human prealbumin

We describe a non-labeled electrochemiluminescence (ECL) immunosensor based on CdSe quantum dots (QDs) for the detection of human prealbumin (PAB, antigen). The immunosensor was fabricated by layer by layer coupled with nanoparticle-amplification techniques. After two gold nanoparticle layers were self-assembled onto the gold electrode surface through cysteamine, anti-PAB (antibody) were conjugated with -COOH groups of both the CdSe QDs and cysteine, which were linked to the gold nanoparticle-modified electrode. The principle of ECL detection was that the immunocomplex inhibited the ECL reaction between CdSe QDs and K(2)S(2)O(8), which resulted in the decrease of ECL intensity. On the one hand, the immunocomplex increased the steric hindrance. On the other hand, the immunocomplex maybe inhibit the transfer of K(2)S(2)O(8) to the surface of the CdSe QD-electrode. The PAB concentration was determined in the range of 5.0 x 10(-10) to 1.0 x 10(-6) g mL(-1), and the detection limit was 1.0 x 10(-11) g mL(-1). The developed CdSe QD-based ECL immunosensor provides a rapid, simple, and sensitive immunoassay protocol for protein detection, which could be applied in more bioanalytical systems.     

Development of a Surface Plasmon Resonance Biosensing Approach for the Rapid Detection of Porcine Circovirus Type2 in Sample Solutions

A sensitive and label-free analytical approach for the detection of porcine circovirus type 2 (PCV2) instead of PCV2 antibody in serum sample was systematically investigated in this research based on surface plasmon resonance (SPR) with an establishment of special molecular identification membrane. The experimental device for constructing the biosensing analyzer is composed of an integrated biosensor, a home-made microfluidic module, and an electrical control circuit incorporated with a photoelectric converter. In order to detect the PCV2 using the surface plasmon resonance immunoassay, the mercaptopropionic acid has been used to bind the Au film in advance through the known form of the strong S-Au covalent bonds formed by the chemical radical of the mercaptopropionic acid and the Au film. PCV2 antibodies were bonded with the mercaptopropionic acid by covalent -CO-NH- amide bonding. For the purpose of evaluating the performance of this approach, the known concentrations of PCV2 Cap protein of 10 µg/mL, 7.5 µg/mL, 5 µg/mL, 2.5 µg/mL, 1 µg/mL, and 0.5 µg/mL were prepared by diluting with PBS successively and then the delta response units (ΔRUs) were measured individually. Using the data collected from the linear CCD array, the ΔRUs gave a linear response over a wide concentration range of standard known concentrations of PCV2 Cap protein with the R-Squared value of 0.99625. The theoretical limit of detection was calculated to be 0.04 µg/mL for the surface plasmon resonance biosensing approach. Correspondingly, the recovery rate ranged from 81.0% to 89.3% was obtained. In contrast to the PCV2 detection kits, this surface plasmon resonance biosensing system was validated through linearity, precision and recovery, which demonstrated that the surface plasmon resonance immunoassay is reliable and robust. It was concluded that the detection method which is associated with biomembrane properties is expected to contribute much to determine the PCV2 in sample solutions instead of PCV2 antibody in serum samples quantitatively.     

血浆(1-3)-β-D-葡聚糖诊断深部真菌感染的临床研究

目的探讨血浆(1-3)-β-D-葡聚糖对早期诊断深部真菌感染的临床价值。方法收集2009年3月～11月间在北京友谊医院感染科住院患者174例,根据侵袭性真菌感染诊断标准,将患者分为排除深部真菌组、确诊组、临床诊断组、拟诊组。应用MB-80微生物动态快速检测系统,检测各组患者血浆(1-3)-β-D-葡聚糖水平,分析比较深部真菌感染组和非深部真菌感染组血浆(1-3)-β-D-葡聚糖的水平。结果深部真菌感染组血清(1-3)-β-D-葡聚糖含量为(153.4±37.0)pg/mL,排除深部真菌感染组血清(1-3)-β-D-葡聚糖含量为(54.6±8.6)pg/mL,两组间有统计学差异(t=3.4,P<0.01);分析血浆(1-3)-β-D-葡聚糖诊断深部真菌感染,以20 pg/mL为诊断阈值,其准确率、敏感性、特异性、阳性预测值、阴性预测值分别为70.1%、87.5%、61.9%、52.1%、91.2%。确诊病例、临床诊断病例、拟诊病例,3组间血清(1-3)-β-D-葡聚糖含量无统计学差异(P>0.05)。结论深部真菌感染组的葡聚糖水平明显高于排除深部真菌感染组的葡聚糖水平,具有统计学意义。以20 pg/mL为诊断阈值,其准确率、敏感性、特异性、阳性预测值、阴性预测值分别为70.1%、87.5%、61.9%、52.1%、91.2%,可作为深部真菌感染的最佳诊断阈值。     

Validation of a liquid chromatography-mass spectrometry method to assess the metabolism of dextromethorphan in rat everted gut sacs

A rapid, sensitive and selective liquid chromatography-mass spectrometry (LC-MS) method was developed for the simultaneous assay of dextromethorphan and its metabolites in tissue culture medium and its intestinal metabolism studied with the rat everted gut sac model. The method was validated in the concentration range of 0.1-2.5 microM (27.1 ng/mL-0.677 microg/mL) for dextromethorphan and 0.005-0.5 microM for dextrorphan and 3-methoxymorphinan (1.28 ng/mL-0.128 microg/mL) and 3-hydroxymorphinan (1.22 ng/mL-0.122 microg/mL). The limits of quantification (LOQ) were 0.0025 microM (12.5 fmoles, 3.4 pg, 5 microL injected) for dextromethorphan; 0.0025 microM for dextrorphan, 3-methoxymorphinan (24.9 fmoles, 6.4 pg injected), and 3-hydroxymorphinan (25.1 fmoles, 6.1 pg injected) with 10 microL injected. The detection of dextrorphan and 3-methoxymorphinan showed that both the P450 isoforms CYP3A and 2D were active in the intestinal mucosa and metabolised dextromethorphan during its passage across the mucosa.