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A dual channel fluorescence system that combines the optical properties of silicon quantum dots–polysilane nanocomposites with those of 2-(4-chlorophenyl)-6-(thiophen-2-yl)pyridine, a fluorescent cytotoxic agent, is presented. The system is capable to alternatively trigger emission signals at two different wavelengths by excitation at a single wavelength. For this purpose a highly stable colloidal dispersion of silicon quantum dots–polysilane nanocomposite is prepared by a one-pot synthetic method using microwave-activated Wurtz coupling of organochlorosilanes. The size and shape of the silicon quantum dots within the polysilane thin film are studied by TEM. The colloidal dispersions are investigated by SAXS, which evidences that polysilane plays also a role as stabilizing agent to prevent aggregation. UV-vis spectrophotometry of the silicon quantum dots–polysilane nanocomposites in the presence of 2-(4-chlorophenyl)-6-(thiophen-2-yl)pyridine is used to define the active wavelength range and establish the fluorescence detection method.