Sensors and detection systems suitable for measuring analytes, such as biomolecule, organic and inorganic species, including environmentally and medically relevant volatiles and gases, such as NO, NO2, CO2, NH3, H2, CO and the like, are provided. Certain embodiments of nanostructured sensor systems are configured for measurement of medically important gases in breath. Applications include the measurement of endogenous nitric oxide (NO) in breath, such as for the monitoring or diagnosis of asthma and other pulmonary conditions.