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Photoluminescent (PL) semiconductor nanocrystals are under high scrutiny owing to their potential for numerous applications. Principally this arises from their excellent optical properties, including narrow and tunable emission bands based on quantum confinement effects. Their bright luminescence and exceptional photostability make these light-emitting materials particularly appealing for biological and material applications such as bio-imaging [1] and photovoltaics. [2] As the number of reports on the preparation and characterization of these nanoparticles (NPs) steadily increases, [3] it is surprising that there have been almost no studies focused on incorporating quantum dots (QDs) into soft supramolecular materials.[4]Here, we report the facile preparation of QD-gel nanocomposites by means of ultrasound. Inorganic semiconductor gels and aerogels, combining porosity and luminescence, have recently appeared as promising new materials.[5] However, their inherent inorganic composition may limit structural variations or functionalization, and applications are still to be demonstrated for these hard materials. On the other hand, supramolecular gels are increasingly interesting due to the tunability of the structure of the gelators responsible for properties that are unprecedented as compared with macromolecular gels. Although the design of a proper chemical structure that will produce a gel still remains as a great challenge, this direction has already met with some success [6] as has the diversification of stimuli that can control such gelation.[7]Our recent discovery of a new dipeptide gelator that can be activated by ultrasound in alkanes and polar solvents [8] allows one to envision several unusual and unexpected applications. A striking feature of this dipeptide is the readily ultrasound-induced gelation in hexane containing CdSe/ZnS core/shell QDs. In this case, ultrasound allows a blurring of the frontier between ''soft'' multi-responsive supramolecular gels and ''hard'' light-emitting semiconductor NPs, affording new materials displaying properties from each component. Here, we describe the preparation of QD-dipeptide nanocomposite gels which show bright luminescence under UV light and which can be switched from liquid to solid by ultrasound and back to liquid when heated. Applications using the gel and the dry material (xerogel) are also demonstrated regarding chemical sensing.Hexane suspensions of CdSe/ZnS QDs [9] covered with trioctylphosphine oxide (TOPO) as surface ligands (Fig. S1 of the Supporting Information) are observed to gel on the minute timescale under ultrasound when dipeptide 1 is present (Fig. 1). The QD-imparted PL is largely retained in the gel state. Furthermore, the previously reported properties of the gel are not significantly affected by the presence of the QDs, [10] with a similar phase transition to a solution after heating to around 75-80 8C (that is here luminescent) followed by cooling to room temperature. The fluorescent gel state can then be recovered when immersing the sa...