Food sensing : detection of bacillus cereus spores in dairy products

Milk is a source of essential nutrients for infants and adults, and its production has increased worldwide over the past years. Despite developments in the dairy industry, premature spoilage of milk due to the contamination by Bacillus cereus continues to be a problem and causes considerable economic losses. B. cereus is ubiquitously present in nature and can contaminate milk through a variety of means from the farm to the processing plant, during transport or distribution. There is a need to detect and quantify spores directly in food samples, because B. cereus might be present in food only in the sporulated form. Traditional microbiological detection methods used in dairy industries to detect spores show limits of time (they are time consuming), efficiency and sensitivity. The low level of B. cereus spores in milk implies that highly sensitive detection methods should be applied for dairy products screening for spore contamination. This review describes the advantages and disadvantages of classical microbiological methods used to detect B. cereus spores in milk and milk products, related to novel methods based on molecular biology, biosensors and nanotechnology

Food Sensing: Detection of Bacillus cereus Spores in dairy products

Milk is a source of essential nutrients for infants and adults, whose production increases worldwide over the past years. Despite developments in the dairy industry, premature spoilage of milk due to the contamination by Bacillus cereus continues to be a problem and causes considerable economic losses. B. cereus is ubiquitously present in nature, and can contaminate milk through a variety of means from the farm to the processing plant, during transport or distribution. There is a need to detect and quantify spores directly in food samples because B. cereus might be present in food only in the sporulated form. Traditional microbiological detection methods used in dairy industries to detect spores show limits of time (they are time consuming), efficiency and sensitivity. The low level of B. cereus spores in milk implies that highly sensitive detection methods should be applied for dairy products screening for spore contamination. This review describes advantages and disadvantages of classical microbiological methods used to detect B. cereus spores in milk and milk products, related to novel methods based on molecular biology, biosensor and nanotechnology

Recent strategies of DNA probe labeling and addressing on electrodes for the development of electrochemical biosensors

International audienc

Stimuli-responsive DNA structures grafted on biosensing surfaces (keynote conference)

International audienc

Bio-fonctionnalisation de surface : application au développement de biocapteurs sensibles

National audienc

Selective functionalization of Au electrodes by electrochemical activation of the "click" reaction catalyst

International audienceThe potential-assisted copper-catalyzed alkyne-azide cycloaddition was investigated to modify a gold electrode surface. Firstly, a tetrathiol-hexynyl derivative was used to introduce alkyne functions on the surface. This anchor proved its robustness in conditions used for the "click" reaction and in wet storage. Then, the potential-assisted "click" reaction was studied with an azido ferrocene derivative. The experimental conditions were optimized according to the electrochemical response of the sensor by cyclic voltammetry and the "click" reaction yield was established. After functionalization, the presence of the 1,2,3-triazole group was confirmed by XPS. A fluorescent azido oligonucleotide was grafted onto the gold surface allowing visualization of the reaction by fluorescence microscopy

Élaboration d'un matériau hybride à base de silice et de polyoxyéthylène (support de synthèse d'oligonucléotides utilisable dans le systèm du diagnostic)

Dans le domaine du diagnostic médical, la détection et la quantification d ADN dans les milieux biologiques complexes font l objet de nombreux sujets de recherche. Les tests reposent sur la reconnaissance de la cible ADN au moyen d une sonde nucléique immobilisée sur un support solide. Ces tests souffrent d un manque de sensibilité dû en partie à la trop faible surface spécifique des supports utilisés, et à la difficulté de fonctionnaliser ces surfaces par les sondes de capture qui permettent l immobilisation de l ADN cible par réaction d hybridation. Afin d améliorer cette phase de capture du test, nous avons proposé d élaborer un support de très grande surface spécifique, et d augmenter ainsi le nombre de sondes greffées. La stratégie mise en place a été l élaboration d un support unique de grande surface spécifique utilisé à la fois pour la synthèse oligonucléotidique et pour le développement des tests diagnostiques. Pour répondre à cet objectif, nous avons élaboré un matériau formé d agrégats de taille contrôlée, constitué de nanoparticules de silice colloïdale aminée reliées entre elles par des polymères de type polyoxyéthylène. Le processus d agrégation des colloïdes a été effectué de manière contrôlée, en utilisant des polyoxyéthylènes fonctionnalisés à chaque extrémité par des groupements isocyanates pour établir des ponts covalents entre les colloïdes. Le matériau ainsi élaboré a été utilisé comme support de synthèse automatisée d oligonucléotide. L évaluation des conjugués (agrégat- oligonucléotide) lors de test d hybridation ADN sur biopuces a été effectuée. Une sensibilité de 6 pM en ADN cible a été obtenue sur le modèle de test étudié, par détection en chimiluminescence de la réaction enzymatique révélant l hybridationLYON1-BU.Sciences (692662101) / SudocSudocFranceF

Click and Bioorthogonal Chemistry: The Future of Active Targeting of Nanoparticles for Nanomedicines?

International audienceOver the years, click and bioorthogonal reactions have been the subject of considerable research efforts. These high-performance chemical reactions have been developed to meet requirements not often provided by the chemical reactions commonly used today in the biological environment, such as selectivity, rapid reaction rate and biocompatibility. Click and bioorthogonal reactions have been attracting increasing attention in the biomedical field for the engineering of nanomedicines. In this review, we study a compilation of articles from 2014 to the present, using the terms "click chemistry and nanoparticles (NPs)" to highlight the application of this type of chemistry for applications involving NPs intended for biomedical applications. This study identifies the main strategies offered by click and bioorthogonal chemistry, with respect to passive and active targeting, for NP functionalization with specific and multiple properties for imaging and cancer therapy. In the final part, a novel and promising approach for "two step" targeting of NPs, called pretargeting (PT), is also discussed; the principle of this strategy as well as all the studies listed from 2014 to the present are presented in more detail

Multi-functionalized silica nanoparticles to improve the sensitivity of diagnostic assays

Keynote invitéeInternational audienc

Nanoparticles with multiple properties for biomedical applications: A strategic guide

International audienc