Detection of Lactobacillus plantarum 299V using microcantilever-based biosensor with dynamic force microscopy

The aim of this study was the detection of active L. plantarum 299v (probiotic microorganism) growth using microcantilever based biosensors in air and in dynamic mode by atomic force microscopy. Commercial cantilevers were cleaned with Piranha solution in order to eliminate contaminants and were functionalized with silylating solution; afterwards the cantilevers were coated by an agarose layer using the capillaries technique. An atomic force microscope in tapping mode was required to evaluate the resonance frequency shift of commercial cantilevers inoculated with L. plantarum 299v. Humidity and temperature were controlled inside an atmospheric hood during the biodetection. The resonance frequency curves were seen to be narrower with higher Q factor values (~219). The results showed that the resonance frequency shifted by approximately 5.2±0.8 kHz on the inoculated cantilevers throughout the growth kinetics. From the resonance frequency curves and known mechanical properties of the cantilevers, the biosensor sensitivity was determined to be 383±3 pg/Hz and the biosensor can detect ~400 bacteria. In addition, L. plantarum growth on the cantilever's surface was confirmed by scanning electron microscopy. The results showed that it is possible to construct a microbiosensor by using commercial cantilevers and atomic force microscopy. These sensors can be used as a platform for the detection of microorganisms associated with functional foods.