Chemical Engineering @ChemengFiles.Com

Investigators from the Consejo Superior de Investigaciones Científicas (CSIC) and Universidad Autónoma de Barcelona have developed a new type of biosensor for rapid detection of infection with Human Immunodeficiency Virus (HIV).

Based on a genetically modified enzyme and a small network of microelectrodes, the biosensor provides a diagnosis in less than an hour. According to the scientific team, the new method is especially useful in geographic areas with insufficient medical resources, as it represents a viable and effective alternative to conventional systems, which require more expensive and complex infrastructure.

The work, which was the subject of a patent application has been published in the journal Analytica Chimica Acta, combines the latest advances in genetics and micro-electronics and is a step in the development of methods for detection of HIV rapid, portable and low cost, according to scientists at the National Microelectronics Center (CSIC) in Barcelona and the Institute of Biotechnology and Biomedicine, Autonomous University of Barcelona.

CSIC researcher Francisco Javier del Campo explains one of the additional advantages of the biosensor: "By working with microelectrodes, the sample volume necessary to make the analysis can be reduced to a few microliters [one millionth of a liter], thereby increasing security analyst and facilitates the subsequent elimination of the remnants generated.

"The sensor is especially suitable for field tests with many samples as they can be made with a portable computer for non-specialists," says Pedro Antonio Villaverde, a researcher at the Department of Genetics and Microbiology, Autonomous University of Barcelona.

The researchers believe further that the use of allosteric enzymes [those who change their enzymatic activity in the presence of certain substances that interact with] as the one used for this biosensor, it opens new opportunities for the detection of other viral infections of veterinary and clinical, such as foot and mouth, swine fever or hepatitis B and C.

The operation of the biosensor is based on the use of a genetically modified enzyme, in combination with a network of microelectrodes that detect electrochemically the products of this enzyme. In the presence of HIV antibodies, the enzyme activity is triggered, which allows us to easily infected samples than they are in less than an hour, a time that investigators planned to shorten in the future by improving the design of microelectrodes.

For the genetically modified enzymes, researchers have used allosteric enzymes. They are inserted by genetic engineering, the areas of viral proteins of the pathogen that causes HIV and against which the immune system produces antibodies. Scientists have used the enzyme beta-galactosidase, which in combination with a substrate (chemical substance that acts on the enzyme), has yielded aminophenol, electroactiva a small molecule that can be easily detected on a network of microelectrodes to rise flow positive.

The system works by adding, simultaneously, a small amount of the allosteric enzyme, both the sample to be analyzed as another sample without the virus that serves as a negative control. After a brief period during which both samples are incubated in parallel, add a small amount of substrate to each sample and compared the evolution of enzyme activity through the production speed of aminophenol on two identical networks of microelectrodes. Samples containing anti-HIV antibodies produced signals significantly higher than the control sample, a total analysis time of less than one hour.