Nanomotion with AFM-cantilevers: clues towards understanding life

The insurgence of newly arising, rapidly developing health threats, such as drug-resistant bacteria and cancers, is one of the most urgent public-health issues of modern times. This menace calls for the development of sensitive and reliable diagnostic tools that are capable of analyzing on a nanometer scale the responses of single cells in biological systems to chemical or pharmaceutical stimuli. Recently our team demonstrated that nanometric scale oscillations exerted by biological specimens reflect the status of the microorganism metabolic activity. Atomic force microscopes (AFM) or low-noise homemade dedicated devices can highlight these oscillations and follow their modifications upon exposure to different chemical or physical stimuli. The method consists of attaching the organism of interest onto a cantilever sensor and following its nano-scale motion as a function of time. We exploited this nanomotion sensor to monitor the activity of several types of bacteria, yeasts and mammalian cells. Here we will review this technique in details, presenting results obtained with many different microorganisms, with a view to highlighting the capabilities of this tool and the potential applications of nanomotion in fundamental research and medical microbiology.