Antibody-Controlled Biosensors Improved by UV Light

Quartz crystal microbalance (QCM) sensors have many uses in biotechnical applications, such as detecting pathogens in blood samples to the study of protein synthesis. With this technology, antibodies anchored to gold electrodes on a piece of quartz crystal act like the “hooks” on the sticky side of a Velcro strap, grabbing molecules of interest as they pass by. The more molecule-sensing antibodies on the surface of the sensor, the more sensitive the QCM device’s detection capabilities.

Regrettably, some of the antibodies typically anchor themselves to the gold plate hook-side-down, making them useless as bioreceptors, decreasing the sensor’s sensitivity. Now, researchers from the University of Naples-Federico II (Italy) and the Second University of Naples (Italy) have found a way to increase the number of right-side-up antibodies in this well-established molecule detection process using light.

In an article published November 2011 in the Optical Society’s open-access journal Biomedical Optics Express, the scientists irradiated antibodies with ultrashort pulses of ultraviolet (UV) light. The UV light is absorbed by the amino acid tryptophan, which breaks the disulfide bridges holding regions of the antibody together and causes a specific part of the amino acid cysteine, called a thiol group, to become exposed at the tail end of the antibody. Because thiol groups are more strongly attracted to the gold electrodes than other areas of the antibody, the bottom sides of these irradiated antibodies become much more prone to stick to the gold electrodes instead of the hook ends. Using this approach, the researchers were able to more than double the sensitivity of the QCM device, creating new avenues for research using this type of sensor.

Related Links:
University of Naples-Federico II
Second University of Naples