Research from the Institute for the Study of Nanostructured Materials at the CNR, published in the journal Advanced Materials, introduces the innovative approach of using organic optoelectronic devices to make a new optical biosensor architecture for checking food safety in minutes

Contamination of food products has a nefarious impact on their quality and poses serious health risks to consumers. 

The presence of microbiological and chemical contaminants in food products can be related to multiple causes such as environmental contamination, agricultural production and raw material processing methods, subsequent storage, packaging and transportation of finished products, to fraudulent adulteration practices.

In addition, contaminated food products must be withdrawn from the market and disposed of because they do not meet European regulatory criteria or quality standards, resulting in wasted food and huge economic loss.

As a result, in recent years there has been a much intensified effort to realize new technologies for sensor technology that is not only fast, accurate, quantitative, and low-cost but also can be easily transferred from analytical laboratories to real working environments (such as farms, water purification sites, and territorial clinics just to name a few examples) to achieve point-of-need (PON) detection.  

To date, the challenge remains open to integrate the multiple technologies needed to enable selective, multiplexing, and highly sensitive sensing into a single miniaturized, robust, and user-friendly system.

"The research activity developed by CNR-ISMN in Bologna and recently published in the journal Advanced Materials," confirmed Stefano Toffanin Dirigente di Ricerca at CNR-ISMN and coordinator of the European H2020 projects MOLOKO and h-ALO, "reports the innovative approach of using organic optoelectronic devices to realize a new optical biosensor architecture precisely because of the peculiar characteristics of these devices such as OLEDs (organic light-emitting diodes) and OPDs (organic photodiodes) of being integrable modular, planar and with thickness of a few hundred nanometers showing optical performance now comparable with competitive technologies based on inorganic semiconductors. 

In the new sensor, the selective, sensitive and multiplexing molecular bio-recognition mechanism typical of nanostructured surfaces exploiting the surface plasmon resonance (SPR) phenomenon is enabled in a chip of about 1 square inch precisely because of the organic optoelectronics that replaced the usual bulky and wasteful optical components that had hitherto prevented the use of SPR technology outside specialized analytical laboratories.

"The broad applicability of the sensor in industrially relevant environments"-the comment of Margherita Bolognesi, Researcher at CNR-ISMN-has been demonstrated in the detection of both high and low molecular weight compounds of interest for safety and quality in the milk production chain: in particular, lactoferrin, which is a protein in cow's milk indicative of mastitis and udder infections in cows, and streptomycin, an antibiotic typically used on livestock farms and which can be easily transferred to meat, milk and other dairy products thus contributing to the dangerous public health problem of antibiotic resistance.

In timescales on the order of 15 minutes per measurement, it was possible to obtain dose-response curves in buffered solutions for these analytes by going on to identify a limit of detection (LOD) comparable with the SPR benchtop analytical instrumentation used as a standard in the laboratory (BIACORE 3000).

"In the future," Toffanin reveals, "the prototype sensor will allow measurements to be taken directly in the field and at all points in the milk supply chain without having to send samples to equipped laboratories: for example, in the milking parlor by direct integration into the milking plant, or at the different sites of interest in the milk supply chain (milk collection centers, dairies, etc.) and is designed to be used as a portable instrument by specialized and non-specialized operators.

Research and development activity on this topic has been supported by the European ICT projects MOLOKO (Grant Agreement No. 780839) and h-ALO (Grant Agreement No. 101016706) within the Horizon 2020 framework program of which CNR-ISMN is coordinator.

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