Food safety is a major factor affecting public health and the well-being of society. A possible solution to control food-borne illnesses is through real-time monitoring of the food quality throughout the food supply chain. The development of emerging technologies, such as active and intelligent packaging, has been greatly accelerated in recent years, with a focus on informing consumers about food quality. Advances in the fields of sensors and biosensors has enabled the development of new materials, devices, and multifunctional sensing systems to monitor the quality of food. In this Review, we place the focus on an in-depth summary of the recent technological advances that hold the potential for being incorporated into food packaging to ensure food quality, safety, or monitoring of spoilage. These advanced sensing systems usually target monitoring gas production, humidity, temperature, and microorganisms' growth within packaged food. The implementation of portable and simple-to-use hand-held devices is also discussed in this Review. We highlight the mechanical and optical properties of current materials and systems, along with various limitations associated with each device. The technologies discussed here hold great potential for applications in food packaging and bring us one step closer to enable real-time monitoring of food throughout the supply chain.

Here, we report the development of a transparent, durable, and flexible sensing surface that generates a fluorescence signal in the presence of a specific target bacterium. This material can be used in packaging, and it is capable of monitoring microbial contamination in various types of food products in real time without having to remove the sample or the sensor from the package. The sensor was fabricated by covalently attaching picoliter-sized microarrays of an E. coli-specific RNA-cleaving fluorogenic DNAzyme probe (RFD-EC1) to a thin, flexible, and transparent cyclo-olefin polymer (COP) film. Our experimental results demonstrate that the developed (RFD-EC1)-COP surface is specific, stable for at least 14 days under various pH conditions (pH 3-9), and can detect E. coli in meat and apple juice at concentrations as low as 10 CFU/mL. Furthermore, we demonstrate that our sensor is capable of detecting bacteria while still attached to the food package, which eliminates the need to manipulate the sample. The developed biosensors are stable for at least the shelf life of perishable packaged food products and provide a packaging solution for real-time monitoring of pathogens. These sensors hold the potential to make a significant contribution to the ongoing efforts to mitigate the negative public-health-related impacts of food-borne illnesses.

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Oligonucleotide‐based microarrays are ideal tools for genetic testing and diagnostics due to their stability, ease of synthesis, and high specificity for the target of interest. This study reports on the effectiveness of several coupling strategies to covalently attach single‐stranded nucleic acids to surfaces, focusing on the robustness of the attachment in various environmental conditions, such as pH and temperature. Various characteristics of DNA microarrays produced using amine‐conjugated DNA probes on five different functional surfaces, commonly used for immobilization of biomolecules, namely, epoxy, carboxyl, amine, aldehyde, and N‐hydroxysuccinimide‐coated substrates, are investigated. Immobilization efficiency, changes in surface energy, as well as the stability of the conjugated DNA upon exposure to various environmental conditions are measured. Finally, in order to study the postimmobilization viability of the developed biosensors, microarrays of synthetic RNA cleaving probes (DNAzyme) are immobilized onto these surfaces and their functionality is evaluated through their ability to detect Escherichia coli at various temperatures. Results show that epoxy‐coated plastic surfaces are most ideal for the creation of DNA‐based biosensing chips. This study provides a guideline for producing oligonucleotide‐based microarrays on glass and plastic substrates and can be used for developing microarray‐based biosensors, suitable for long‐term storage.

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