High sensitivity miniaturized immunoassay sensor based on biomolecules concentration phenomena at nanoscale

Nowadays a rapid diseases diagnosis and timely appropriate and personalized treatments are critical determinants to favor optimal clinical outcomes. Recent biosensors exploiting micro- and nano-fabrication technologies have the potential to deliver point-of-care diagnostics that match or surpass conventional standards in regards to accuracy, time and costs[1].  Nanofluidic devices seem to be one of the best candidates in fact, both the nanometric dimensions of the structures and the size of biomolecules (i.e. DNA or proteins) make them useful in many applications such as separation, detection and manipulation of biomolecules[2]. Here, we used a funnel-shaped nanochannel, directly created on the surface of a micro-machined silicon mould by using a Focus Ion Beam (FIB) and then replicated, using Poly(DiMethylSiloxane) (PDMS), with REplica Moulding (REM) techniques, reducing the fabrication costs and allowing high-throughput production of sophisticated nanofluidic devices[3]. In this work, we firstly analyzed the electro-hydrokinetic transport properties of PDMS nanostructures by comparing electrooptical measures and simulations. In particular, we showed how to concentrate different charged molecules inside nanochannel while constant voltages are applied to the device. Then, combining biomolecules concentration phenomena and an appropriate functionalization of the nanochannel’s polymeric surface with antibodies, linked by using APTES (3-Aminopropyl)triethoxysilane and GA (Glutaraldheyde)[4], we were able to decrease biomolecules’ sensing limit for the detection of one or several targeted antigens. Especially, we identified through fluorescence microscopy and electric measurements, the uptake of Inteleukin-10 (IL10), very diluted in solution (from 12.5pg/ml to 1.25pg/ml), by the nanochannel surface functionalized with anti-IL 10.