While enzymatic biosensors were recognized as a leap into elevated or ultimate selectivity, the next stage in biosensor design includes gene based sensors involving DNA; as the recognition or coupling entity (via hybridization), antibody or antigen based biosensors; and whole cell sensors. Within the agri-food industry, pathogen detection trends have focused on the utilization of single sensor platform for detection of multiple pathogens/toxins. More recently, biotechnology has shifted into ever smaller systems to allow for portability, cost reduction, analysis time reduction and commercial viability.  Improvements in microfabrication systems have similarly aided in advancing biosensor technology and utility. Emerging nanomaterials, such as nanoparticles and nanofibers have featured in these, paving the way for this miniaturization trend.

Such functional nanomaterials enhance electrochemical biosensors in two ways: refining the response features of the electrode by increasing its surface area for instance and assisting in robust attachment of the bioreceptor/recognition entity.  With greater surface to area volume ratios, nanomaterials lend greater catalytic prowess, ensure biocompatibility and achieve lower mass transfer resistance. This translates to improved selectivity, sensitivity, time efficiency and cost effectiveness for the biosensor. Similarly, the increase in transducer surface area delivers greater conductivity and sensitivity, promotes greater interaction capacity and lowers detection limits. These are all ideal features of a biosensing interface.  An excellent example of a nano-biosensor, capable of pesticide residue detection in concentrations as low as 0.4 pM, has been reported in by Verma et al. Furthermore, the inclusion of other nanomaterials at the transducer level, for example carbon nanotubes, can increase electron transfer and increase the transducer activity. Evidence of these improvements is in the slow but gradual replacement of traditional enzyme-substrate biosensors by nano-biosensor technology. Nano-biosensors have been developed for the agriculture and food processing industries to identify and quantify pesticides, herbicides, pathogenic microorganisms and other microbial contamination such as viruses and bacteria, hormones, glucose, as well as the presence of insects or fungus.

Another medium of interest is microfluidics which provides throughput processing, reduces sample and reagents volume (down to the nanolitre), increases sensitivity, and employs a single platform for both sample preparation and detection. Microfluidics are portable, disposable, offer real-time detection, and simultaneous analysis of different analyzes in a single device with exceptional accuracy. For example, microfluidic nano-biosensor for the detection of pathogenic species like Salmonella have already been proposed recently.

It is envisaged that the ever improving analytical properties of electrochemical transducers will even allow for the detection of multiple analytes simultaneously. However, despite these promising advances and the potential of nanomaterial-based biosensors, realistically their application within food matrices is still in the very early stages of development. Compared with other biosensing forays, for example in medicinal biosensor technology through favored point of care and home diagnostics for pregnancy, glucose content, biosensing in food production and processing or screening has not been embraced as readily.