RaptaDiag

RaptaDiag

RaptaDiag is a small or medium-scale focused research project supported by the European Commission under the 7th Framework Programme with Grant agreement no. 304814. It contributes to the programme FP7-HEALTH-2012-INNOVATION-2, topic HEALTH.2012.2.3.0-1: Diagnostics for infectious diseases in humans

EVA-Biosensor technology

EVA-Biosensor technology

The exciting light beam is reflected under total internal reflection at the liquid-solid interface at the bottom of the well. By this optical phenomenon a 200 nm bottom layer of the adjacent liquid is selectively illuminated. Only fluorophors localised in this evanescence field will absorb and emit.

Microacustic-resonating technology

Microacustic-resonating technology

Continuous flow cell for microbial detection (top). The detector consists of a quartz microbalance (bottom left) with the associated electronic system for oscillation excitation and resonance readout (bottom right).

Liquid crystal biosensor technology

Liquid crystal biosensor technology

Example of an aligned lyotropic liquid crystal cell between crossed polarisers, appearing dark when aligned with the polarisers (left), and bright when rotated (right). Perturbations in the alignment are almost visible with the naked eye, and easily visible with a hand held 10x microscope (bottom).

Rapid aptamer based diagnosis for bacterial meningitis

The main objective of RaptaDiag is to develop a fast, easy-to-use, inexpensive diagnostic test for Neisseria meningitides and Streptococcus pneumonia. These two agents are currently considered the main bacterial agents causing bacterial meningitis, a disease which is on the World Health Organization´s Top-10 list of lethal infectious diseases. It is estimated that N. meningitides and S. pneumonia are responsible for 80% of the meningitis cases.

The aim of this project is to develop a portable biosensor device that overcomes the problems encountered with the currently available technologies, based on the detection of these agents by culture or PCR on cerebrospinal fluid, which are too expensive, take too long to give an accurate result and are too complex to be of general use outside major hospital facilities. The test will therefore address the clinical need for a rapid and cost-effective diagnosis of this disease, which shows a high degree of morbidity, reducing the possibility of misdiagnosis, and abuse of antibiotics.

Microorganism recognition is achieved by the use of novel aptamer receptors. Aptamers are short single stranded DNA/RNA molecules, which by intra-strand pairing of the nucleic bases undertake a 3-dimensional structure which is then selected based on its high affinity and specificity towards the desired antigen or target. Aptamers show a number of advantages over antibodies. Furthermore, the low unit price of aptamers allows for a high number of receptors to be deposited on the active area of the sensor –thus increasing the sensitivity without compromising the total sensor cost. New highly specific aptamers will be developed by Partner 1 (Universidad Politécnica de Madrid) during the project, targeting N. meningitides and S. pneumonia.

The impact of the project will be maximised by employing three different sensor technologies, which will employ aptamers as common receptor. The first technology is the adaptation of the commercial evanescent biosensor technology (EVA-Biosensor), core sensor technology of Partner 2 (Davos Diagnostics AG), to use aptamer receptors instead of antibodies. Two more experimental technologies, developed by Partner 1 (Universidad Politécnica de Madrid), a microacoustic-resonating biosensor (MRS) and a liquid crystal based biosensor (LCS) will be employed for developing a rapid test at significantly lower cost. Each of the three sensor approaches has their own advantages:

  • The EVA-Biosensor represents a forefront, yet commercially available multiplex sensor technology and proven for rapid (10min) and quantitative immunoassay tests.
  • The MRS will carry a high density of receptors, having the potential to detect the binding of one microorganism alone, which is the ultimate detection limit.
  • The LCS will open the way for an exceedingly simple and inexpensive qualitative detection method, with either visual (without the need for any instrumentation) or simple optoelectronic inspection with miniature readers or even mobile phone cameras.

Both MRS and LCS employ direct, label-less detection. Partner 3 (Jonsman Innovation ApS) will design the fluidic chip incorporating the LCS.

The three technologies will be developed with a single use disposable diagnostic chip and a portable detection unit. Two kinds of detection units are targeted: a laboratory version, for use in hospitals and a portable version for use in remote areas and low resource settings, and smaller independent medical care units. Emphasis is on the “simplicity and robustness of use” and fulfilling “off-grid” requirements using only a minimal amount of energy, no access to data sources (internet) available and autonomy of at least 12 hours.
Rapid aptamer based diagnosis for bacterial meningitis