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Posted: Mar 18, 2014

Innovative nanosensor technique to conduct faster bioassays

(Nanowerk News) This technique was developed by researchers of the Universidad Politécnica de Madrid (UPM) in collaboration with the Universidad Complutense de Madrid (UCM) and the Universidad Politécnica de Valencia (UPV). This technique is low in cost because the device used (CD or DVD) is available in shops at an affordable price. Also, these optical sensors can directly detect biomolecules without using markers ("Aluminum nanohole arrays fabricated on polycarbonate for compact disc–based label-free optical biosensing"). These advantages translate into a significant cost and time saving because of the tasks of preparing and conducting tests.
This optical nanosensors research consists of the development of optical sensors on CD surfaces with the purpose of studying biological samples using standards CD players. Its optical reader examines the biological samples placed on the disc in a similar way that the recorded pits are read. The small size of the nanosensors were designed, manufactured and featured at the Institute of Optoelectronics Systems and Microtechnology (ISOM) of UPM, led by Carlos Angulo Barrios, one of the main researchers in this project.
The optical data storage technologies based on CDs and DVDs are highly developed and its presence in consumer electronics is enormous. The digital data storage (“zeros” and “ones”) is recorded in polycarbonate compact disc through small marks or pits following a spiral path (track) over the disc surface. The CDs or DVDs reader crosses the disc surface with a laser beam that detects the presence of pits and reads them as “zeros” and “ones” thanks to the associated optoelectronics instrumentation.
Nanosensors consist of dimensional arrays of nanoholes of 250 nanometres (nm) drilled in aluminum 100 nm of thickness. These nanometrics structures transmit light facilitating the detection of the molecules found on the surface. Researchers have developed a technology that adapts the production production of polycarbonate materials, which are the ones used to make CDs and DVDs.
Also, in addition these mentioned technological processes have been optimized specially to make aluminum devices. Noble metals such as gold are usually used to make this type of sensors thanks to its strong chemical resistance. However, the high price of gold is a serious obstacle for mass production. Aluminum is 25,000 times cheaper than gold, but the problem is it cannot be used for nanosensors because it tends to corrosion in aqueous environments. The developed technology avoids the problem of corrosion and makes suitable sensors for the analysis of a great variety of biological samples.
Another significant characteristic of the sensors made on CDs surfaces is the capacity to detect directly biomolecules without using markers. This saves time and cost when preparing the samples in comparison to the common devices used for biological or clinical analysis that in addition require a marker (fluorescent or radioactive).
The developed technology by UPM allow the usage of common CDs and DVDs devices as the support to store many biological samples, just like a commercial player that has minimal modifications for chemical analysis. The usage of these consumer electronics for this purpose means a drastic cost saving comparing to the current specialized instrumentation for the analysis of many biological samples. In addition, the small size and weight of the CDs readers facilitate the equipments portability to access rapidly in different locations.
Source: Universidad Politécnica de Madrid
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