DIY instrumentation

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  • Published: Nov 1, 2008
  • Author: David Bradley
  • Channels: Infrared Spectroscopy
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Rather than designing and building new instrumentation from bespoke components, researchers in Canada have turned to the laser-based optical read-write technology of DVD and CD players to create a biomedical diagnostics system that requires no hardware modifications.

Hua-Zhong "Hogan" Yu and his colleagues Yunchao Li, Lily M. L. Ou in the Department of Chemistry, at Simon Fraser University, in Burnaby, British Columbia, Canada, are all for recycling. Previously, they hacked an inkjet printer to allow them to "print", or rather microfabricate, a lab-on-a-CD using standard inkjet technology. At the time, Yu told SpectroscopyNOW that, "Inkjet printing combined with chemical etching can make different gold microstructures, with designed pattern and dimensions these could be used for surface-plasma resonance or disk-spinning interferometry and surface-enhanced Raman spectroscopy studies."

Now, the SFU researchers have turned to another aspect of biomedical science and have reported a digital signal readout protocol for screening disc-based bioassays that uses a standard optical drive from an ordinary desktop computer.

"Microarray technology is a powerful tool for the high-throughput analysis of specific interactions between biological macromolecules (DNA, proteins, and carbohydrates)," explains Yu, "However, its applications in gene profiling, clinical diagnosis, immunoassays, and drug discovery, for instance, are currently limited to well-funded biomedical laboratories or hospital settings due to the requirement for expensive equipment (such as robotic spotters and laser fluorescence scanners). Inexpensive instrumentation could open up such studies to less well-funded laboratories, perhaps in the developing world.

Yu and others have previously shown that polycarbonate (PC) plates can be employed as alternative substrates to glass in microanalytical applications. Given that compact discs are made from polycarbonate, Yu and colleagues reasoned that they might be able to exploit these pre-manufactured substrates. Moreover, the characteristic optical phenomena that occur on the metal layer within the sandwich of materials that is a compact disc might also be exploited in the development of biosensors based on interferometry or surface plasmon resonance, the researchers explain. Their work on embedded microfluidic functions into CDs, particularly for the control of fluid transfer by disc spinning and laboratory-on-a-disk devices have already attracted widespread interest from industry.

Various teams have modified CD/DVD hardware and yet others have hacked software to exploit these characteristics, but harsh solvents and detection sensitivity have limited research somewhat.

Yu and colleagues wanted to answer a key question: Can we replace complex and expensive test equipment with ordinary computers for on-site biomedical diagnostics? And, can we really "read" biorecognition reactions on disk with standard optical drives?

They have now answered in the affirmative by describing a novel readout protocol for the multiplex screening of biomolecular binding events, which takes advantage of the reading-error correction function embedded in standard audio CDs. An "enhancement" step is required to boost the assay signals by autometallography, but they did not need to carry out any hardware mods or software hacks because a free CD quality-analysis program could be used to detect and quantitate the binding events.

"Because this technique does not require any changes to the computer hardware or software, it is readily accessible and suitable as platform technology for rapid, high-throughput, and point-of-care biomedical diagnostics," the researchers say, "In addition, the surface chemistry we have demonstrated herein, i.e., to prepare robust, multiplex bioassays (for biotin streptavidin binding, DNA hybridization, and antibody antigen interaction) on polycarbonate surfaces via covalent bonding, is potentially useful in the fabrication of other types of polymer-based microanalytical devices."

The team's novel readout protocol is an order of magnitude more sensitive than conventional fluorescence labelling and scanning, relying as it does on the high-resolution technology of the CD/DVD. It also has the capability of examining many microassays on the same disc.

Reference:

Research Blogging Yunchao Li, Lily M. L. Ou, Hua-Zhong Yu (2008). Digitized Molecular Diagnostics: Reading Disk-Based Bioassays with Standard Computer Drives Analytical Chemistry, 80 (21), 8216-8223 DOI: 10.1021/ac8012434


Hogan Yu
Yu hacking computer technology for biomedical scientists 

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