Nanolithography techniques enable the fabrication of complex nanodevices that can be used for biosensing purposes. However, these devices are normally supported by a substrate and their use is limited to in vitro applications. Following a top-down procedure, we designed and fabricated composite inductance-capacitance (LC) nanoresonators that can be detached from their substrate and dispersed in water. The multimaterial composition of these resonators makes it possible to differentially functionalize different parts of the device to obtain stable aqueous suspensions and multi-sensing capabilities. For the first time, we demonstrate detection of these devices in an aqueous environment, and we show that they can be sensitized to their local environment and to chemical binding of specific molecular moieties. The possibility to optically probe the nanoresonator resonance in liquid dispersions paves the way to a variety of new applications, including injection into living organisms for in vivo sensing and imaging.