Label-free biodetection by optical diffraction
Label-free biodetection techniques are the matter of intense research field in bioassays area. We have developed a label-free detection method based on optical diffraction. Probes molecules are immobilised on functionalized glass slides by soft lithography to generate molecular gratings that efficiently diffract light from a laser beam. Diffraction efficiency increases with the thickness of the molecular gratings. According to this principle, the measured diffraction intensity is found to increase when probe-target interactions take place at the surface of the molecular gratings. To collect and compare diffracted intensity before and after interaction, we have developed a dedicated scanner to measure the 1st order diffracted beam.
- Label-free biodetection
- Low-cost fabrication
- Amandine M.C. Egea, Laurent Mazenq, Emmanuelle Trévisiole, Vincent Paveau and Christophe Vieu, Optical label free biodetection based on the diffraction of light by nanoscale protein gratings, Microelectronic Engineering, 2013, V.111, p.425-427
- Patent : Jean-Christophe Cau, Helene Lalo, Jean-Pierre Peyrade, Childerick Severac and Christophe Vieu Method of seeking at least one analyte in a medium likely to contain it, 2010, WO 2010/029139
- H. Lalo, Thèse INSA, Toulouse, 2009
- J.C. Cau, Thèse INSA, Toulouse, 2009
- J. Foncy, Thèse INSA, Toulouse, 2013
Microfluidic to manage reliable molecular interactions
Low density microarrays for diagnosis require automatized and reproductible protocol interactions that ensure homogeneous repartition of the solutions over the spots of the microarray and that can be removed easily for allowing optical reading. We have developed a generic and removable microfluidic interface using magnetic field to ensure a uniform and sealed contact between the microfluidic cartridge and the microarray. This microfluidic platform was validated for automated immunodiagnosis on microarray. In addition, this approach allows a reduction of volumes provided by miniaturization.
View of the microfluidic interface reversibly sealed to a microarray.
This approach is versatile, easy to produce and provides an effective and automated platform for multiplexed immunodiagnosis.
- Label-free biodetection
- Low-cost fabrication
- A. Ali-Cherif, S. Begolo, S. Descroix, J.-L. Viovy, L. Malaquin, Programmable magnetic tweezers and droplet microfluidic device for high-throughput nanoliter multi-step assays, Angewandte Chemie International Edition, 2012, 51, 10765
- Saliba, A.E. ; Saias, L.; Psicharia, E.; Minc, N.; Simon, D.; Mathiot, C.; Bidard, F.C.; Pierga, J.Y.; Fraisier, V.; Salamero, J.; Saada, V.; Farace, F.; Vielh, P.; Malaquin, L.; Viovy, J.L. Microfluidic Sorting and High Content Multimodal Typing of Cancer Cells in Self-Assembled Magnetic Arrays, Proceedings of the National Academy of Sciences, 2010, 107(33), 14524-9
- M.L.Y. Diakité, J. Champ, S. Descroix, L. Malaquin, F. Amblard, J.-L. Viovy, A low-cost, label-free DNA detection method in lab-on-chip format based on electrohydrodynamic instabilities, with application to long-range PCR, Lab on Chip, 2012, 12, 4738
- S. Miserere, G.Mottet, V.Taniga, S.Descroix, J.-L.Viovy, L.Malaquin, Fabrication of thermoplastics chips through lamination based techniques, Lab on Chip 2012, 12, 1849
- Begolo, S.; Colas, G.; Viovy J.L.; Malaquin, L., New Family of Fluorinated Polymer Chips for Droplet and Organic Solvent Microfluidics, Lab on Chip 2011, 11, 508
- J. Autebert, B.Coudert, F.-C. Bidard, J.-Y.Pierga, S. Descroix, L.Malaquin, J.-L.Viovy, Microfluidic: an innovative tool for efficient cell sorting, Methods 2012, 57,297
- Saias, L; Autebert, J; Malaquin, L; Viovy J.-L., Design, modeling and characterization of microfluidic architectures for high flow rate, small footprint microfluidic systems, Lab on Chip 2011, 11, 82
Magnetic clamped microfluidic device for automated immunodiagnosis on microarrays, E. Crestel, J. Foncy, JP. Borges, A. Estève, JC Cau, C. Vieu, L. Malaquin, E. Trévisiol. Micro and Nano Engineering 2015.
Microfluidic interface for microarray diagnostic
Keywords : microfluidics, reversible magnetic clamp, multiplexed immunoassay, allergen microarray
Reference: Reversible magnetic clamp of a microfluidic interface for the seric detection of food allergies on allergen microarrays, J. Foncy, E. Crestel, J-P Borges, A. Estève, J-C Cau, C. Vieu, L. Malaquin and E. Trévisiol, Microelectronic Engineering (2016).
To provide a robust platform for fluid handling, most microfluidic devices usually involve irreversible bonding methods to achieve a leak free interface between the microchannels and the holding substrate. Such an approach induces a major drawback when biological interactions are performed on a microarray format as it is difficult to recover the biochip for further fluorescence scanner analysis. This work describes an automated microfluidic platform using a reversible magnetic clamp for multiplexed immunodiagnostis. The microfluidic device is composed of a magnetic PDMS layer (containing iron powder) coated by PDMS, which is reversibly clamped to an epoxysilane glass slide containing an array of various antigens. The microfluidic device was validated for in vitro diagnosis of food allergies on an allergen microarray after serum interaction. The statistical analysis of spot intensities(Signal to noise ratios) on the microarray displayed excellent reproducibility. In addition to the reduction of volumes provided by miniaturization, this approach is versatile, easy-to- produce and provide an effective platform for multiplexed immunodiagnosis based on conventional fluorescent detection schemes.
Fig 1: Schematic view of the microfluidic device. Magnetic PDMS cartridge and the microarray are hold together by magnetic force using array of magnets under the device. a) Microfluidic cartridge composed by PDMS and a magnetic PDMS layer, b) microarray composed by an epoxysilane glass slide containing an array of various antigens (85 spots), c) the microfluidic cartridge and the microarray reversibly sealed by a magnetic field to ensure a conform and hermetic contact, d) section view of the device, e) View of the microfluidic interface.
Reversible magnetic clamp of a microfluidic interface and a glass slide spotted with a microarray of allergens for serum detection of food allergies
The PDMS microfluidic cartridge is transparent above the channels allowing optical imaging in the microfluidic device while the reversibility of the magnetic clamp allows the reading of the microarray after microfluidic removal using a conventional fluorescent scanner.
No leakage was observed below 150 mBar with the magnetic clamp.
The functionality of the device was validated for in vitro diagnosis of food allergies in the serum of a patient.
Fig 2: a) Microarray fluorescence image of the interacting spots after removal of the microfluidic reversible chip, b) signal to noise ratio quantification after food allergy immunodiagnostic using the microfluidic device. The patient was allergic to cow milk, coat milk and yolk eggs.