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Rangées de graines.. © INRA, Elena Schweitzer © Fotolia

Our results

  1. Introduction
  2. Human milk digestion in the preterm infant: impact of technological treatments
  3. Research & Innovation 2017 - For Food and Biobased Products
  4. The way in which proteins aggregate when heated may change their sensitising potency
  5. Enhancing the viability of spray-dried probiotic bacteria by stimulating their stress tolerance
  6. To stick or not to stick? Pulling pili sheds new light on biofilm formation
  7. When biopolymers selfassemble: a balance between energy and entropy.
  8. Mimicking the gastrointestinal digestion in a lab-on-a-chip:the microdigester
  9. How a milk droplet becomes a powder grain
  10. Research & Innovation 2016 - For Food and Bioproducts
  11. A new process for the biorefining of plants
  12. Under the UV light : the bacterial membrane
  13. Reverse engineering or how to rebuild ... bread!
  14. Green Chemistry: a step towards lipid production in yeast
  15. Individually designed neo-enzymes for antibacterial vaccines
  16. Multi-scale mechanical modelling: from the nanometric scale to the macroscopic properties of bread crumb
  17. Minimill: 500 g to assess the milling value of soft wheats
  18. Microbial production of lipids for energy or chemical purposes
  19. The discrete role of ferulic acid in the assembly of lignified cell wall
  20. Eco-design of composites made from wood co-products
  21. Analysis of volatile compounds enables the authentication of a poultry production system
  22. Nanoparticles as capping agents for biopolymers microscopy
  23. Pasteurisation, UHT, microfiltration...All the processes don't affect the nutritional quality of milk in the same way
  24. Integration of expert knowledge applied to cheese ripening
  25. Controlling cheese mass loss during ripening
  26. The shape memory of starch
  27. Research & Innovation 2015 - For Food & Biobased Products
  28. Behaviour of casein micelles during milk filtering operations
  29. Overaccumulation of lipids by the yeast S. cerevisiae for the production of biokerosine
  30. Sequential ventilation in cheese ripening rooms: 50% electrical energy savings
  31. An innovative process to extract bioactive compounds from wheat
  32. Diffusion weighted MRI: a generic tool for the microimaging of lipids in food matrices
  33. Characterization of a major gene of anthocyanin biosynthesis in grape berry
  34. New enzyme activity detectors made from semi-reflective biopolymer nanolayers
  35. Improving our knowledge about the structure of the casein micelle
  36. Heating milk seems to favour the development of allergy in infants
  37. Fun with Shape
  38. Using volatile metabolites in meat products to detect livestock contamination by environmental micropollutants
  39. SensinMouth, when taste makes sense
  40. A decision support system for the fresh fruit and vegetable chain based on a knowledge engineering approach
  41. SOLEIL casts light on the 3D structure of proteins responsible for the stabilisation of storage lipids in oilseed plants
  42. A close-up view of the multi-scale protein assembly process
  43. Controlling the drying of infant dairy products by taking water-constituent interactions into account
  44. Polysccharide nanocrystals to stabilise pickering emulsions
  45. Discovery of new degradative enzymes of plant polysaccharides in the human intestinal microbiome
  46. A durum wheat flour adapted for the production of traditional baguettes
  47. Virtual modelling to guide the construction of « tailored-made » enzymes
  48. How far can we reduce the salt content of cooked meat products?
  49. Diffusion of organic substances in polymer materials: beyond existing scaling laws
  50. Smart Foams : various ways to destroy foams on demand !
  51. Dates, rich in tannins and yet neither bitter nor astringent
  52. Sodium content reduction in food
  53. Research & Innovation 2014

New enzyme activity detectors made from semi-reflective biopolymer nanolayers

The aim of the nanosciences and nanotechnologies is to control the architecture of objects whose size ranges from the nanometer to several hundred nanometers in order to discover new intrinsic functionalities linked to these scales. Our recent research has focused on the production of fine films with nanometric dimensions made from biopolymers deposited on a reflective substrate. The fineness of these layers leads to the appearance of colours as a result of interference phenomena. The action of an enzyme (a hydrolysis, for example) can modify the thickness of the layer and, therefore, the colour of the device, thus making it possible to rapidly detect enzyme activity with the naked eye. Because of the thinness of the layers and, as a result, the small quantities of biopolymers used, the extreme sensitivity of the device is improved by a factor of 200 in some cases, compared to classical colorimetric methods used to detect enzyme activity.

Updated on 06/17/2013
Published on 06/05/2013

Controlling the construction of biopolymer assemblies to create a new function: colours without a colouring agent, structural colours

When a fine film is deposited on the surface of a reflective substrate, a colour appears when the thickness of the layer reaches between 70 and 200 nm.  The colour is due to a light wave interference phenomenon: part of the incident ray is reflected on the air-film interface, whereas the other part passes through the layer and then reflects on the second film/substrate interface (silicon, in our case). Since the reflected rays have different optical paths, they are in phase displacement and interfere among themselves, leading to the appearance of a colour. The colour is therefore not due to the presence of a colouring agent but to the assembly architecture. This phenomenon, well known in certain insects and plants, is referred to as a structural colour1. It can also be obtained from a film formed of biopolymers.  When this film is placed in contact with a solution containing an enzyme capable of degrading the biopolymer, the alteration of the film leads to either the disappearance or the modification of the colour.
These types of detectors had never been made before and our research led to the filing of a patent application. These detectors could, for example, be used as high-throughput screening tests for enzyme activity banks (metagenomic banks, for example) or could even make it possible to easily monitor the expression of an enzyme in a growing medium. The main advantages of this method compared to existing methods are:

  • The ease of implementation because the activities are detected visually without the need for equipment or sophisticated environments
  • Detection speed (several minutes)
  • Detection sensitivity
  • The possibility of miniaturising the method, allowing it to be integrated into high-throughput screening devices

Rapid, simple and sensitive detection

The first films made consist of cellulose and xyloglucan nanocrystals obtained by sequential deposits of the two constituents (Fig.).  This method makes it possible to precisely control the thickness of the layers and, therefore, the colour and sensitivity of the device.  The films obtained were subjected to degradation by a commercial cellulase capable of hydrolysing xyloglucan and cellulose, compared to a traditional method used in cellulose activity screens.  After several minutes of application, the surfaces were washed and dried.  The modification of the colour indicates the action of the enzyme.  The technique proved to be extremely simple to use and could be rapidly implemented.
The results obtained revealed that this method is much more sensitive than the screening methods normally used to look for new enzymes.  The sensitivity observed compared to a classical colorimetric method was increased by a factor of 50.  We have since extended this method to other biopolymers (pectins, xylans, proteins, etc.), and the sensitivities determined were up to 200 times better than those found with the colorimetric detection methods used as a reference.

Nanometric films are obtained by successive deposits of cellulose and xyloglucan. The growth of the film is linear in relation to the number of deposits (n), and a colour appears after several cycles. The layers are submitted to the action of cellulose solutions with different enzymatic activities. After several minutes of incubation followed by washing and drying, the colour of the layer is modified or totally disappears.. © INRA
Nanometric films are obtained by successive deposits of cellulose and xyloglucan. The growth of the film is linear in relation to the number of deposits (n), and a colour appears after several cycles. The layers are submitted to the action of cellulose solutions with different enzymatic activities. After several minutes of incubation followed by washing and drying, the colour of the layer is modified or totally disappears. © INRA

Towards new high-throughput screening tests    

The application-oriented aim of our research is now to develop, in partnership with teams specialised in microsystems, the miniaturisation of these devices and their integration into 96-well plates, the most common format for the robotised screening of genomic banks compatible with all of the commercial automated systems. The use of this method will allow the rapid and sensitive screening of banks that are currently being developed, particularly as a result of the increased interest in metagenomics and the stakes involved in white biotechnologies.   


See also

  • Patent: Method for detecting hydrolytic enzyme activities without labelling, using reflective biopolymer layers. Carole Cerclier, Bernard Cathala. Patent N° FR 1055529 of 7 July 2010
  • Photonic structures in biology, Vukusic, P.; Sambles, J. R. Nature, (424), (6950), 852-855, 2003.
  • Elaboration of Spin-coated Cellulose-Xyloglucan Multilayered Thin Films, Carole Cerclier, Fabrice Cousin, Hervé Bizot, Céline Moreau and Bernard Cathala, Langmuir, 26 (22), pp 17248–1725, 2010.
  • Cerclier C., Lack-Guyomard A., Moreau C., Cousin F., Beury N., Bonnin E, Jean B., Cathala B. (2011) Coloured Semi-reflective Thin Films for Biomass-hydrolyzing Enzyme Detection. Advanced Materials 23: 3791–3795s