Compact optical diagnostic device for isothermal nucleic acids amplification.

We recently reported the successful use of the loop-mediated isothermal amplification (LAMP) reaction for hepatitis B virus (HBV) DNA amplification and its optimal primer design method. In this study, we report the development of an integrated isothermal device for both amplification and detection of targeted HBV DNA. It has two major components, a disposable polymethyl methacrylate (PMMA) micro-reactor and a temperature-regulated optical detection unit (base apparatus) for real-time monitoring of the turbidity changes due to the precipitation of DNA amplification by-product, magnesium pyrophosphate. We have established a correlation curve (R 2 = 0.99) between the concentration of pyrophosphate ions and the level of turbidity by using a simulated chemical reaction to evaluate the characteristics of our device. For the applications of rapid pathogens detection, we also have established a standard curve (R 2 = 0.96) by using LAMP reaction with a standard template in our device. Moreover, we also have successfully used the device on seven clinical serum specimens where HBV DNA levels have been confirmed by real-time PCR. The result indicates that different amounts of HBV DNA can be successfully detected by using this device within 1 h.

A miniaturized germanium-doped silicon dioxide-based surface plasmon resonance waveguide sensor for immunoassay detection.

A surface plasmon resonance (SPR) waveguide immunosensor fabricated by germanium-doped silicon dioxide was investigated in this study. The designed waveguide sensor consisted of a 10 microm SiO(2) substrate layer (n=1.469), a 10 microm Ge-SiO(2) channel guide (n=1.492) and a 50 nm gold film layer for immobilization of biomolecules and SPR signal detection. The resultant spectral signal was measured by a portable spectrophotometer, where the sensor was aligned by a custom-designed micro-positioner. The results of the glycerol calibration standards showed that the resonance wavelength shifted from 628 to 758 nm due to changes of refractive index from 1.36 to 1.418. Flow-through immunoassay on waveguide sensors also showed the interactions of protein A, monoclonal antibody (mAb ALV-J) and avian leucosis virus (ALVs) resulted in wavelength shifting of 4.17, 3.03 and 2.18 nm, respectively. The SPR dynamic interaction could also be demonstrated successfully in 4 min as the sensor was integrated with a lateral flow nitrocellulose strip. These results suggest that SPR detection could be carried out on designed waveguide sensor, and the integration of nitrocellulose strip for sample filtering and fluid carrier would facilitate applications in point-of-care portable system.

The design and fabrication of two-dimension multi-electrodes array chip and system.

We reported a design and fabrication by using microelectro-mechanical-systems (MEMS) processes of a planar 64-channel multielectrode-array (MEA) chip for recording and/or stimulating cells or tissue slice. The 8 multichannels recording system was designed to verify the bioelectronic signal detected from the MEA chip. The active electrode area can be 20 mumx20 mum or 40 mumx40 mum and with 200 mum or 140 mum space between electrodes, and the metal circuit layout is protected by thin silicone dioxide. Then, the DC measurement to prove this MEA chip device can detect bio-electronic signal normally and immersing the MEA chip in the physiological saline buffer solution to verify that the performance in the AC condition.

Surface plasmon resonance biochips for tuberculosis bacillus detection.

Tuberculosis is one of notifiable infectious diseases which may cause serious epidemic problems. Traditional diagnostic techniques include acid-fast stain, bacteria culture, metabolic monitoring have some disadvantages such as low sensitivity, time consumption and less specificity. In this study we proposed a new diagnostic technique based on the protein chips concept which detected by SPR phenomena. It was found that the resonance angle approximately 51.86 degrees ) shifted slightly toward right with antibody concentration of 10X, 30X, 100X, and 300X dilution under optimal concentration of immobilized TB antigen W38 (MW 41.5 kDa, 50 mug/ml). While for the W06 (MW 14 kDa, 50 mug/ml), the resonance angle was around 50.13 degrees and shifted with the same trend as W38 did.