This paper describes an integrated biomechanical platform for real-time molecular or cellular assays. This platform is composed of silicon nanotweezers to manipulate the biological samples and an open microfluidic to handle solution and reactive agents. The tweezers are fabricated by standard Silicon-On-Insulator based micromachining processes (2 masks +1 additional mask for special tips) and integrate actuator, trapping tips and sensor. The microfluidic device is produced from common polydimethylsiloxane (PDMS) micromolding and integrates active valves for controlling the biological medium. Combining both technologies, a versatile experimental setup, built up in an enclosed space (< 10 cm(3)), enables direct interrogation of molecules or cells in solution. The silicon nanotweezers sense slight biological modifications of the trapped molecules or cell by monitoring the mechanical resonance response, which keeps a high Q factor (over 20) in liquid. Biomolecular assays (molecule trapping and enzymatic reaction kinetics) as well as characterizations of cells are reported here. The system provide molecular level resolution and is sensitive enough to capture cell biomechano-transduction activities. Moreover as the system is handy, it may be an easy, fast and quantitative alternative to existing methods.