Lab-on-a-chip method

In order to apply the real-time PCR technology as a rapid, accurate, and direct detection tool for field or point-of-testing applications, it is highly desirable to miniaturize the real-time PCR instrument. To miniaturize the real-time PCR and make it a lab-on-a-chip method, one must realize the following two key functions (1) Control the on-chip thermal cycling, i.e., control the temperature of the PCR reaction wells on the chip. (2) Detect the fluorescent signals during the PCR. 

The assay itself is conducted imaginably simply by parallel funneling the sample fluid through the capillary tubes and determining the extent of conversion. The latter can be accomplished by UV spectrometry, lab-on-a-chip methods, and so on. In fact, the MER-based assay allows for replacing time-consuming photometric measurements or tedious preparations of dose-response curves (Figure 4.12b). 

Manipulation of a droplet on a solid surface is of growing interest because it is a key technology to construct lab-on-a-chip systems. The imbalance of surface tensions is known to cause spontaneous motion of a droplet on the surface, as mentioned above. The wetting gradient causing liquid motion has been prepared by chemical [32], thermal [37], electrochemical [3] and photochemical [38-40] methods. 

Sakai-Kato, K., Kato, M., Ishihara, K. and Toyo-oka, T. (2004) An enzyme immobilization method for integration of biofunctions on a microchip using a water-soluble amphiphilic phospholipid polymer having a reacting group. Lab on a Chip, 4, 4—6. 

Challenges remain in the development of lab-on-a-chip sensing systems. The overall lifetime of a sensor chip is always determined by the sensor with the shortest lifetime, which in most cases is the depletion of reference electrolytes. Measures to minimize cross-talking among sensors, especially when biosensors are integrated in the system, also should be implemented [122], The development of compatible deposition methods of various polymeric membranes on the same chip is another key step in the realization of multisensing devices. 

The analysis of biomolecules by AFM is sometimes [3] referred to as surface biology, as opposed to the so-called test-tube biology, because the immobilisation of oligonucleotides on sohd surfaces is central to the design, fabrication and operation of DNA-based microdevices, such as biosensors, DNA micro- and nanoarrays, microPCR and lab-on-a-chip devices. As the analysed biomolecules are in close contact and very often in intimate interaction with the surface, sample preparation for the AFM analysis of surface-immobihsed biomolecules is both critical and dehcate. The biomolecules need to be firmly anchored on the substrate, which has to have a sufficiently minimal or easily discriminated topography [1]. The Kleinschmidt method [6] for the DNA... 

Figure 13.1 Depiction of the glass-based lab-on-a-chip fabrication method. Shown in the figure is (a) the photoresist and chrome-coated glass substrate, (b) the coated substrate exposed to UV light through a mask (black rectangle), (c) removal of the exposed photoresist, (d) removal of the exposed chrome layer, (e) removal of glass by wet chemical etching, (f) removal of the bulk photoresist, and (g) removal of the bulk chrome layer.

Figure 13.2 Illustration of the various types of injection methods for lab-on-a-chip applications (a) floating, (b) direct, (c) pinched, and (d) gated. The labeled positions are as follows for panels (a), (b), and (c) reservoir 1 is for buffer, reservoir 2 for sample, reservoir 3 for sample waste, and reservoir 4 is for buffer waste. For panel (d), reservoir 1 is for sample and reservoir 2 is for buffer.

LAB-ON-A-CHIP EXPLOSIVES DETECTION UTILIZING OPTICAL METHODS 271... 

Of all the detection methods applied to the lab-on-a-chip, the most popular by far has been laser-induced fluorescence (LIF) detection. Direct LIF detection benefits... 

Lab-on-a-Chip Explosives Detection Utilizing Optical Methods / 271... 

First, a general method of transformation of the expression plasmid into E. coli will be described, as well as appropriate conditions for growth and induction of the expression cultures. Then, the 96-well protein purification method is detailed. Last, analysis of the purified proteins is described using both lab-on-a-chip technology and traditional sodium dodecyl sulfide (SDS)-polyacryla-mide gel electrophoresis (PAGE). 

Peterbauer T, Heitz J, Olbrich M et al (2006) Simple and versatile methods for the fabrication of arrays of live mammalian cells. Lab on a Chip 6(7) 857-863... 

There has been a trend toward electrochemical reactions in lab-on-a-chip devices in the last few years.51,52 This is mainly because miniaturized electrodes can be fabricated using microfabrication methods and solutions can be transferred by microfluidics approaches.5354 Flow injection analysis and sequential injection analysis techniques were also employed for electrochemical enantioselective high-throughput screening of drugs.55... 

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