Highly sensitive molecular detection using FRET-based semiconductor nanowire lasers

Owing to the stimulated emission, microlasers can amplify subtle FRET signals arising from molecular interactions, enabling them to serve as ultrasensitive optical sensors for detecting target molecules. However, most FRET-based microlasers use organic fluorophores as donors or acceptors, which face challenges in long-term stability and repeatability due to photobleaching. Here, we develop a FRET-based semiconductor nanowire laser as a highly sensitive nanoscale probe for detecting low-concentration molecules. Mediated by the amplified FRET signals on the nanowire surface by evanescent field coupling, both the lasing intensity and wavelength of the probe exhibit stable linear correlations over a wide dynamic range of the logarithmic molecular concentrations (100 pM to 10 μM), with a detection limit as low as 4 pM. Its superior photostability overcomes the limitations of organic dyes, offering a robust platform for miniaturized, high-performance biosensors.