Introduction

The present invention relates to nanosensors, in particular nanosensors for biological, medical and environmental applications, and more specifically a three-dimensional nanoresonator structure dispersible in a liquid. The invention also relates to a specific process for manufacturing three-dimensional nanoresonators dispersible in a liquid, for example water, by means of lithographic techniques. The nanoresonators, also known by the name of nanoantennas, are resonant devices having nanometric dimensions which, exposed to a broad spectrum of electromagnetic excitation radiation, exhibit an increased absorption at their own resonance frequency, This absorption results determined by the characteristics of the resonator structure and/or by interactions with the environment in which they are immersed, in a THz and near infrared wavelength range. The present invention has the aim of realizing free three-dimensional nanoresonators, i.e. free from any substrate and dispersible in a fluid medium, which have resonance properties that can be granted in a wide spectrum of wavelengths by a tailored design of the resonant structure, and sensitive to the chemical-physical characteristics of the environment in which they are dispersed or to the presence of specific molecular species.

Technical features

The invention is based on a lithographic three-dimensional nano-resonator fabrication technique in which an array of nano-resonators is designed and transferred on a substrate by lithographic techniques. The individual nano-resonators are subsequently released from the substrate and possibly subjected to chemical modifications for the functionalization of at least one of their accessible surfaces exposed to the environmental interactions. The nanoresonators object of the invention have a three-dimensional layered overall structure, with layers composed by different materials, whose shape and dimensions can be controlled by design. Their functionalizations can be such as allowing a free dispersion of the nanoresonators in water or other fluid media, in order to create probes sensitive to predetermined molecular interactions or to generate affinity towards specific tissues, cells or materials being analyzed. The nanoresonators obtained according to the present invention have characteristics that significantly extend the range of applications, combining the design flexibility properties of the resonance frequency in a wide electromagnetic spectrum (typical of the two-dimensional nanoresonators of the prior art) with the dispersibility properties of the resonant nanoparticles.

Possible Applications

• study of transparent materials in THz;
• in vivo analysis as a diagnostic tool or to detect physiological or biochemical events
• the use in fluidic or microfluidic assays in which the immersion fluid medium influences the overall dielectric constant of the resonant circuit
• impregnate porous materials, such as marbles or stone-made artworks for the study and diagnostics of cultural heritage
• analysis of specific tissues or cells, using them conjugated with appropriate functional groups
• monitor gene expression, reveal proteins or enzymes in tissues and cells, or for toxicological purposes;
• environmental applications, for example in the detection of chemical pollutants even in a liquid environment.

Advantages

• plurality of areas exposed to the environment, for layers of different materials, and a multiple functionalization of the nanoresonator (for so-called multi-sensing uses)
• greater sensitivity respect to the nanoparticle-based approaches of the prior art
• Ease of nanofabrication process at the chosen resonance frequency;