A mixture of two amphiphiles with fluorescent head groups can be used as a sensing ensemble for the pattern-based analysis of aminoglycoside antibiotics. In buffered aqueous solution, the amphiphiles form a dynamic mixture of micellar aggregates. In the presence of aminoglycosides, the relative amount and the composition of the micelles is modified. The re-equilibration of the system is analyte-specific, and characteristic fluorescence spectra are obtained for different aminoglycosides. Accurate differentiation in the low micromolar concentration range can be achieved by a principal component analysis of the spectral data.