Lab-on-a-chip (LOC) is a catchall term that is used to describe analysis devices that operate on a nanoscale. An LOC is a system that integrates multiple laboratory activities into the bounds of a single chip, the size of more or less a quarter.

LOC technology was built and evolved from what started off as microarrays and can now be applied to perform analyses and functions far more complex and greater in number than by conventional microarrays. One can say that LOC is the marriage of microfluidics into chip technology. LOC miniaturises bioanalytical techniques and integrates them into a microfabricated format.

Another term that is often associated with LOC is micro-total-analytical-systems (microTAS). This is an ambiguous term that cannot be confidently applied to all LOCs. Strictly regarded, LOC indicates the scaling of single or multiple lab processes, not necessarily restricted to analysis, down to chip format, whereas microTAS is dedicated to the integration of the total sequence of lab processes to perform chemical analysis.

LOC in drug making
The field of drug discovery and development has been a slowly progressing one as only a handful of several thousands of compounds discovered enter and actually pass out of the clinical trials. This makes the process of discovering and developing new drugs a time-consuming and multibillion dollar business. Here is where concepts such as microfluidics and LOC technologies are believed to contribute by way of aiding the potential synthesis of thousands of individual molecules in microchannels in minutes, instead of the hours and days needed using traditional drug discovery methods.

Traditional laboratory techniques used for drug discovery include sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE), size exclusion chromatography (SEC), reversed-phase HPLC, capillary electrophoresis (CE) combined with quadrupole or ion trap mass spectrometry (MS/MS) and matrix-assisted laser-desorption ionisation time-of-flight spectrometry (MALDI-TOF).

The critical need to reduce drug discovery and development costs and most importantly, ever growing demand for sample throughput have led to the adoption of microfluidic chip technologies by those involved in chemistry, biochemistry, pharma and analytical sciences to miniaturise the procedures and techniques presently conducted in the laboratory.

The tight regulation of new drug market entry and the finite nature of patent date expiry make it difficult to recover research and development costs while keeping the drug costs reasonable. All of these have led to a shift of technology from traditional time consuming methods toward combinatorial and high-throughput chemistry, which produce a wide range of chemically diverse sets of compounds for the lead discovery process. Automation and miniaturisation are the key concepts that have helped accomplish these developments.

Researchers expect the use of microfluidics and LOC technologies, which embrace these two enabling concepts, to offer a number of ways of meeting the current challenges faced in the drug discovery sector today, and they believe they will take the field to great heights. These technologies aid in a more efficient identification of lead compounds and a quicker screening of a large number of compounds in smaller quantities.

LOC technologies are expected to play a major role in the field of pharmaceuticals development mainly for preclinical and clinical trials. Their use would involve the evaluation of the efficacy and the toxicity of drug candidates, and in the long run, possibly the screening and selection of effective lead drug compounds. The screening process is critical for the identification of the desired molecules amongst a large variety of chemical species and those that may have the expected reaction on a biological target and the desired therapeutic effect. Such a screening process also aids in the identification of the molecule's structural features that influence its pharmacological activity and toxicity. Other major targets of application include the study of ADME characteristics of potential drugs.

(Courtesy: Technical Insight, Healthcare Practice, Frost & Sullivan)