Methods, compositions and articles of manufacture for assaying a sample for a target polynucleotide are provided. A sample suspected of containing the target polynucleotide is contacted with a single-stranded sensor polynucleotide complementary to the target polynucleotide and an agent that allows the sensor polynucleotide itself, when present in single-stranded form, to fluoresce upon excitation. The sensor polynucleotide is optionally conjugated to a substrate, which may be an optoelectronic sensing device, and can be micro- or nanoaddressable. A chromophore may be used to adsorb energy from the excited sensor polynucleotide and emit light. The methods can be used in multiplex form. Sensing devices incorporating the sensor polynucleotide and optionally the chromophore are also provided. Kits comprising reagents for performing such methods are also provided.