QCM Aptasensor for Rapid and Specific Detection of Avian Influenza Virus

There has been a need for rapid detection of Avian Influenza virus (AIV) H5N1 due to it being a potential pandemic threat. Most of the current methods, including culture isolation and PCR, are very sensitive and specific but require specialized laboratories and trained personnel in order to complete the tests and are time-consuming. The goal of this study was to design a biosensor that would be able to rapidly detect AIV H5N1 using aptamers as biosensing material and a quartz crystal microbalance (QCM) for transducing method. Specific DNA aptamers against AIV H5N1 were immobilized, through biotin and streptavidin conjugation, onto the gold surface of QCM sensor to capture the target virus. Magnetic nanobeads (150 nm in diameter) were then added as amplifiers considering its large surface/volume ratio which allows for faster movement and a higher target molecule binding rate. The result showed that the captured AIV caused frequency change, and more change was observed when the AIV concentration increased. The nanobead amplification was effective at the lower concentrations of AIV, however, it was not significant when the AIV concentration was 1 HA or higher. The detection limit of the aptasensor was 1 HAU with a detection time of 1 h. The capture of the target virus on to the surface of QCM sensor and the binding of magnetic nanobeads with the virus was confirmed with electron microscopy. Aptamers have unlimited shelf life and are temperature stable which allows this aptasensor to give much more consistent results specifically for in field applications.

Development of H5 subtype-specific monoclonal antibodies (MAb) and MAb-based assays for rapid detection of H5 avian influenza

Avian influenza (AI) virology surveillance is the most important method to monitor AI virus (AIV) in poultry so as to effectively prevent and control AI outbreaks. Monoclonal antibodies (MAb)-based assays are highly sensitive and specific for AIV detection, and much practical and economic for test-in-field or onsite. Many such assays have been developed and are still in developing since the H5N1 highly pathogenic AI (HPAI) outbreaks occurred in South East Asia in 2003. A MAb-based dot-enzyme-linked immunosorbent assay (ELISA) has been developed in our lab during late 1990s and early 2000s. Meanwhile, AIV H7 and H5 subtype specific-MAbs have been successfully developed in our laboratory to enhance the Dot-ELISA and other MAb-based assays for AIV detection. Production and purification of the H7 and H5 MAbs were made to provide essential reagents for Dot-ELISA and other immunoassays, and the current development of a novel Biosensor technique for rapid detection of AIV from clinical and field specimens.

量子点免疫标记法同时检测2种食源性致病菌

目的:建立快速检测金黄色葡萄球菌、福氏志贺氏菌的量子点免疫标记方法。方法:利用免疫磁珠富集,量子点标记,微型光纤光谱仪对金黄色葡萄球菌、福氏志贺氏菌进行定量检测,建立荧光强度与菌浓度的定量模型,并对捕获条件进行优化。结果:两种目标菌的最佳捕获条件为免疫捕获时间45 min、磁分离时间1.5 min、PBS浓度0.01 mol/L。目标菌浓度在10~2~10~5 CFU/m L范围,目标菌与荧光强度的线性关系为:金葡菌FI=9.2744lg N+50.14,福氏志贺氏菌FI=18.616lg N+53.784,N为目标菌细菌菌落数,CFU/m L;FI为荧光强度值。金黄色葡萄球菌决定系数R^2=0.9626,福氏志贺氏菌决定系数R^2=0.9778,说明具有很好的拟合性。重复性测试结果中相对标准偏差为2.9%,检测时间在2 h内。结论:本文建立的检测方法简单,快速,灵敏度高,特异性好,具有很好的应用前景。

A data-driven health indicator extraction method for aircraft air conditioning system health monitoring

Prognostics and Health Management(PHM) has become a very important tool in modern commercial aircraft. Considering limited built-in sensing devices on the legacy aircraft model,one of the challenges for airborne system health monitoring is to find an appropriate health indicator that is highly related to the actual degradation state of the system. This paper proposed a novel health indicator extraction method based on the available sensor parameters for the health monitoring of Air Conditioning System(ACS) of a legacy commercial aircraft model. Firstly, a specific Airplane Condition Monitoring System(ACMS) report for ACS health monitoring is defined. Then a non-parametric modeling technique is adopted to calculate the health indicator based on the raw ACMS report data. The proposed method is validated on a single-aisle commercial aircraft widely used for short and medium-haul routes, using more than 6000 ACMS reports collected from a fleet of aircraft during one year. The case study result shows that the proposed health indicator can effectively characterize the degradation state of the ACS, which can provide valuable information for proactive maintenance plan in advance.

Therapeutic effect of electroacupuncture,massage,and blocking therapy on external humeral epicondylitis

OBJECTIVE:To compare two therapeutic methods:electroacupuncture + massage + blocking therapy,and blocking therapy alone in the treatment of external humeral epicondylitis.METHODS:Eighty-six patients were randomized into two groups with 43 in each. The treatment group received electroacupuncture + massage +blocking therapy, while the control group received blocking therapy only. A course of electroacupuncture treatment included therapy once a day for 10days. There were 10 treatments in a massage course and massage was given once a day, with a1-week interval given before the next course. A course of blocking treatment included therapy once a week, for twototaltreatments,andgenerallyno more than three times. The therapeutic effects were evaluated with the visual analog scale(VAS),grip strength index(GSI) score, and Mayo elbow performance score(MEPS) before treatment and at0, 6, 12, and 24 months after treatment to observe thetotaleffectiverate.RESULTS: In the treatment and control groups before treatment and at 0, 6, 12, and 24 months after treatment, the VAS scores were: 6.5±1.9 and 6.4±1.6; 4.6±1.3 and 4.6±1.7; 4.8±1.3 and 4.8±1.2; 4.6±1.2 and 6.6±1.6; and 6.5±1.6 and 6.5±1.3, respectively. The GSI scores were 63±8 and 63±8; 84±6and82±7;82±7and82±6;84±6and62±8;and64±6 and 64±7, respectively.The MEPS of both groups were65±7and66±8;85±6and84±7;84±5and84±7;80±7and66±6;and65±6and65±7,respectively.The total effective rates of the treatment and control groups at 0, 6, 12, and 24 months after treatment were 87.5% and 85.0%; 85.0% and 82.5%;80.0% and 12.5%; and 2.5% and 5.0%, respectively.Compared with the treatment group, the control group had greater joint function, better the rapeutic effect, and lower pain intensity(P<0.01), indicating a high recurrence rate in the 12th month after treatment.There were no differences inVAS, GSI, or MEPS at 0, 6, and 24 months after treatment(P>0.05)betweenthetwogroups.CONCLUSION: We found that both methods were effective for external humeral epicondylitis. After 6months of treatment,the effects were good in both groups. However, in the 12th month, the control group had a relatively severe relapse. After 24months, both groups relapsed. The effect of electroacupuncture, massage, and blocking therapy used in combination lasted longer, delaying the recurrence of the disease.

Detection of Staphylococcus Aureus using quantum dots as fluorescence labels

Staphylococcus aureus(S.aureus)has been identified as one of the major foodborne pathogenic bacteria.The development of rapid detection methods for S.aureus is needed for assuring food safety.In this study,quantum dots were used as fluorescent labels in an immunoassay for quantitative detection of S.aureus.Firstly,biotin-labeled anti-S.aureus antibody was conjugated with streptavidin-coated magnetic nanobeads(180 nm diameter)and used to separate S.aureus cells.Then streptavidin coated quantum dots(QDs)were conjugated with biotin-labeled anti-S.aureus antibody and used as the fluorescence labels to mix with the separated S.aureus.Finally the fluorescence intensity of the bead-cell-QD complexes was measured at a wavelength of 620 nm.A linear relationship between S.aureus cell number(X)and fluorescence intensity(Y)was found for cell numbers ranging from 10^(3) to 10^(6) CFU(Colony Forming Unit)/mL,and the detection limit was 10^(3) CFU/mL.The regression model can be expressed as Y=7.68X+35.06 with R^(2)=0.94.The detection of S.aureus in food sample was explored initially.The fluorescence intensity of food sample was close to the background,so it was not satisfied.Further study will focus on the application of the method for detection of S.aureus in food sample.

LabVIEW-based impedance biosensing system for detection of avian influenza virus

In order to detect the multiple avian influenza viruses(AIVs)rapidly,specifically and sensitively,a LabVIEW and microelectrode array-based impedance biosensor was developed and demonstrated.A laptop with LabVIEW software was used to generate excitation signals at different frequencies with an audio card and measure the impedance of target viruses through a data acquisition card.The audio card of the laptop was used as a function generator,while a data acquisition card was used for data communication.A virtual instrument was programmed with LabVIEW to provide a platform for impedance measurement,data processing,and control.Six interdigitated microelectrodes were placed at the bottom of six wells on a microplate to form six sensors for different AIVs and controls.Then,AIV specific ligands were immobilized on the microelectrode surface to capture target viruses.To enhance the sensitivity,AIV specific aptamers conjugated gold nanoparticles and thiocyanuric acid were employed to form a network structure and used as an amplifier.Results of the measured impedance were compared with a commercial IM6 impedance analyzer,and the error was less than 5%.The developed biosensor was portable with the sensitivity and specificity for applications to on-site or in-field rapid screening of avian influenza viruses.