Rapid SPR for parallel detection of pathogens in blood
In the RaSP project, the partners will develop a fast, cheap and at the same time very sensitive method, which has the potential to detect more than 100 blood pathogens simultaneously. A new type of surface plasmon resonance (SPR) transducing principle will be exploited, which allows an essential increasing of the sensitivity compared to the state-of-the-art SPR systems. The consortium aims at the simultaneous detection of the pathogens HIV, hepatitis C, hepatitis B and syphilis to demonstrate the capabilities of the system. In parallel, a simple version of the system will be set up that will allow for the detection of the presence of any of the mentioned blood pathogens.
Biological materials like blood, tissues and organs now represent a daily routine material that our hospitals and research institutes handle for many preventive, therapeutic, and research applications. They represent hope for many medical situations, but at the same time they pose a risk of transmitting diseases via blood transfusion, tissue transplantation or organ transplantation. Thus, there is an urgent need to improve the technologies used for screening diseases such as HIV and hepatitis C. The same need exists to test donor blood in a cheap and fast way, especially in less developed countries where the rate of infected blood is high due to high prevalence of diseases.[+] Read More
The RaSP partners are proposing an immunosensing diagnostic assay, which can be used without labels and amplification. A new type of SPR transducing principle will be exploited which allows very fast and sensitive testing: the development of most transducers for chemical and biological sensors has reached the level at which they are limited by fluctuations of physical (temperature, pressure) and chemical (concentrations of reagents) parameters in the close vicinity of the sensing spots.
In the RaSP project, the partners apply a new solution providing a breakthrough for these limitations. The approach is based on the use of distributed sensing and reference spots. Instead of single macroscopic reference spots, numerous miniaturised reference spots placed between miniaturised sensing spots are used.
During the signal processing, the signals from all (or numerous selected) reference and sensor spots are taken into account. This leads to a decrease in temperature fluctuations (as well as in pressure, reagent concentrations and other parameters). The level of these fluctuations is less than that between two miniaturised sensing and reference spots, while the total surface of the spots remains macroscopic, thus suppressing shot noise and other noise sources caused by miniaturisation of the sensor surface.
The described innovations will be realised and will lead to a highly sophisticated SPR system capable of detecting numerous analytes simultaneously with a high resolution. Thus, numerous pathogens in a blood sample can be detected speedily, and in parallel. Sophisticated transducer chips with an array of capture molecules are needed in this system. The antibodies to four pathogens will be randomly distributed through the transducer chip.
The output of the system provides information on whether any of these four pathogens is present in the blood sample. This information is sufficient for many applications and will lead to the exclusion of blood, tissue or organs for transfusion or transplantation.
Fig 4: Experimental setup for testing the improved RaSP transducer chips. The setup is based on a Biosuplar 6.321 SPR Reflectometer provided by Mivitec GmbH.
The biological idea of the biosensor will depend mainly on the Antigen-Antibody reaction. In contrast to methods like the enzyme linked immunosorbent assay (ELISA), the detection will be performed without any time-consuming reaction and with minimal human error and/or risk by detection of layer growth due to coupling between the antigen and its antibody on the transducer chip. The main achievement will be the multiple specificity of the chip as it will have specificity for all the pathogens required, unlike other methods that can be used for only one pathogen at a time.
The expected outcome of RaSP is a desktop system, which is easy to use and leads to accurate results within a limited reaction time (typically 10 to 20 minutes). The system will be tested in two countries against standard testing methods like ELISA. The resulting diagnostic system will represent a revolution in the field of rapid diagnostics. Its applications in the medical sector will reduce the risk of dealing with contaminated biological materials and will help to prevent persons from becoming severely ill. The system and test will be suited for easy detection of the four most prevalent bloodborne infections that matter in the process of blood transfusion. It can be conducted in one step, on location where the blood is collected from donors, and it does not need any sophisticated laboratory preparation.
The RaSP system could become a standard system for screening donor blood. Furthermore, other bioanalytical applications are conceivable for this system, such as the detection of emergency markers, food monitoring (detection of food-related pathogens) and monitoring of environmental pathogens and biological warfare agents.