Abstract: The present invention is directed to a nanoparticle loaded with a light sensitive molecule and a method of preparing the nanoparticle, wherein the nanoparticle is a colloidal gold nanoparticle and the light sensitive molecule is non-covalently adsorbed to the surface of the nanoparticle. The present invention is also directed to a nanoprobe comprising the nanoparticle and further comprising a targeting moiety covalently coupled to the surface of the nanoparticle. Additionally, the present invention is directed to an imaging method comprising administering the nanoprobe to a subject and collecting imaging data of the subject or part of the subject with optical multimodality imaging. A method of treating cancer in a subject comprising administering the nanoprobe and performing photodynamic therapy on the subject is further disclosed.

Abstract: Various embodiments relate to a substrate for optical sensing by Surface Enhanced Raman Spectroscopy (SERS). The substrate comprises a support, a first layer consisting of a plurality of metal nanoparticles attached to the surface of the support, and a second layer consisting of a plurality of metal nanoparticles attached to the surface of the metal nanoparticles of the first layer, wherein the mean diameter of the metal nanoparticles of the first layer is greater than the mean diameter of the metal nanoparticles of the second layer. Various embodiments also refer to methods for forming the substrate. In a further aspect, various embodiments refer to a biosensor comprising the inventive substrate for the detection of an analyte in a sample by SERS, a method for the detection of an analyte in a sample by SERS using the biosensor, and use of the biosensor in SERS detection methods.