European Project - DETECTHIV


Project full title: Sensitive nanoparticle assay for the detection of HIV

Project Acronym / Number: DETECTHIV / LSH-6-No.037118

Call: FP6-2005-LIFESCIHEALTH-6

Area: LSH-2005-1.2.2-3 Development of new diagnostics: Nanoparticles-based diagnostics

Type of Instrument: Specific Targeted Research Project (STREP)

Internet: http://www.detecthiv.eu

Partners involved:

1. Ecole Polytechnique Federale de Lausanne, Switzerland (coordinator)
2. Katholieke Universiteit Leuven, Belgium
3. Ayanda Biosystems SA, Switzerand
4. Bertin Technologies, France
5. Ecole Superieure de Physique et de Chimie Industrielles de la ville de Paris, France
6. Denmark Technical University, Denmark
7. Ademtech, France

Abstract:

We will develop a new platform and assay for the detection of HIV p24 antigen in serum or blood. The advantages of a p24 test are that it can detect HIV at an early stage of the infection, before antibodies develop, and that it is quantitative. The DETECTHIV project aims at developing an extremely simple viral load test with only one reactant (grafted colloids). In a first phase, a magnetic nanoparticles assay will be developed for use in a microtiter plate with as goal a detection limit of 1 ng/ml. In a second phase, the use of nanoparticles on a microfluidic chip will permit to detect p24 to levels as low as 0.1 picog/ml, one to two orders of magnitude more sensitive than classical Enzyme Linked Immuno-Sorbent Assay (ELISA) p24 tests. Validation of our platform will be both done with recombinant p24 samples and patient samples.

The principle of our test consists in optically detecting the formation of a colloidal gel of magnetic nanoparticles (agglutination test). The gel forms in a magnetic field under the presence of antigens that are capable of linking irreversibly two colloidal particles. Therefore the latter are grafted with antibodies that are specific to the p24 antigen. An agglutination test requires only one step with only one reactant and the detection is achieved through simple optical absorbance measurements, owing to the strong optical scattering modification when passing from nanometric colloids to the gelled state.

In the microfluidic chip test, a sample solution of serum or blood is transported through a suspension of magnetic nanoparticles that are magnetically suspended within a microfluidic channel. When brought into a magnetic field, the particles will be able to approach each other, form chains and will be irreversibly linked if the p24 antigen is present. Subsequently, on-chip light scattering techniques will be used to quantify the concentration of permanent chains or clustered beads, which is proportional to the p24 antigen concentration.





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