Activated fluorescence was achieved for nanoparticle based systems. One particulate system consisting of a poly(propargyl acrylate) (PA) core with covalently attached derivatized fluorescein and modified bovine serum albumin covalently conjugated to a cyanine 3 derivative was initially nonfluorescent. Upon trypsin addition and subsequent proteolytic digestion, Förster resonance energy transfer (FRET) was induced. The other particulate system consisted of a PA core with covalently attached azide modified BSA, which was covalently attached to a silicon phthalocyanine derivative (PA/BSA/akSiPc600). Both systems were biocompatible. To investigate activated fluorescence with the PA/BSA/akSiPc600 system in cancer cells, human non-small cell lung cancer cells (A549 cell line) were used as a model system. The PA/BSA/akSiPc600 system was incubated with the cells at varying time points in an effort to see a fluorescence increase over time as the cells uptake the particles and as they digest the BSA, most probably, via endocytosis. It was seen, through live cell scanning confocal microscopy, that the fluorescence was activated in the cell.
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