Thermocycling automated

After amplification, tlie products can be detected by various methods. Simple gel electrophoresis with ethidium bromide staining may suffice. When greater accuracy is required, one of the primers can be fluorescently labeled so that after PCR the fragments are accurately sized on a DNA sequencing device. Alternatively, some form of hybridization assay can be used to verify or analyze the amplified product. Automated methods are always attractive and closed-tube methods are particularly advantageous in the clinical laboratory. Adding a fluorescent dye or probe before amplification allows thermocyclers equipped with optical detection to analyze the reaction as it progresses (real-time PCR) or after the reaction is complete (endpoint measurement) without need to process the sample for a separate analysis step. 

The GOOD assay is a single tube procedure. The five reaction steps are done without transferring the samples to new reaction vials. Reagents are simply added to the reaction and the samples either placed in an incubator or thermocycler. This makes it amenable for automation. 

Figure 8. Reaction sequence scheme of the GOOD assay. The method consists of pipetting, incubation, and thermocycling steps and is therefore easy to automate.

The motivation for miniaturization of PCR was driven by several factors. First, PCR should be made faster in order to get results more quickly. Second, larger sets of samples should be processed. Third, DNA-based diagnostics should be evolved from a laboratory technique requiring experienced specialists to an automated on-site diagnostic method operated after brief instructions by anybody. Finally, the amplification by PCR should be integrated in a diagnostic chain (p-TAS concept) and implemented in a miniaturized transportable system. The power consumption of the thermocycling process should be as low as possible. 

Classically, the PCR is conducted in automated devices, thermocyclers, which require approximately 90 min for completion of 40 cycles. What makes... 

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