RÉSUMÉ

Foodborne outbreaks due to the consumption of contaminated food products result not only in hospitalization and death, but also places a large economical burden on the food industry due to product recall and disposal. Traditional methods for detecting pathogens are relatively costly, time-consuming, and expert related. Therefore, rapid, accurate and in-situ approaches for identifying bacteria in the food industry are urgently needed to overcome the problem that can be widespread easily. Recently, smart food packaging has evolved to meet the demands of customers and the food industry, especially in early recognition techniques of pathogens or spoilage bacteria.

The first part of this work focuses on the detection of volatile organic compounds which may be produced by bacterial growth. The proposed method relied on using silver nanoparticle embedded in bacterial cellulose, allowing a colorimetric technique. The results demonstrated that the prepared plasmonic nanopaper is very sensitive to various concentrations of ammonia vapor. As ammonia is one of the primary compounds of bacterial spoilage in meat and fish, the proposed platform was assessed against the produced gases during spoilage. Thus, these results opened the window to an innovative technique for examining the spoilage in meat and fish by smart packaging.

In the second part of this research, we studied the development of a biosensor for detection of bacteria. To design a promising biosensor, a solid surface platform was considered with the appropriate features to support the biorecognition and transducer elements. Interestingly, we found that bacterial cellulose impregnated with gold nanoparticles addressed the demands for such a system, owing to the plasmonic properties of gold nanoparticles and abundant functional groups available in the bacterial cellulose. The synthesized nanopaper presented a novel solid surface with quenching ability that can be utilized in fluorescence detection approaches such as FRET (Förster resonance energy transfer).

In the third part, a biosensor for bacterial detection was assembled by using FRET and based on the obtained results from the second step of this research. The carboxylated bacterial cellulose embedded with gold nanoparticles served as the acceptor and simultaneously cross-linked to the biorecognition element as the solid platform. Quantum dot conjugated to anti-E. coli played as the donor which bonded to the protein A/G immobilized on the surface of carboxylated bacterial cellulose. The photoluminescence of the QD endured a reduction once the anti-E. coli conjugated QD interacted with the respective bacteria. So, the distance between the QD and the surface of the acceptor was reduced, as the consequence of the inherent conformational change in the antibody structure after interacting. Through this strategy, E. coli was recognized with a LOD (limit of detection) about 10 CFM.mL-1.