Noncontact Metal–Spiropyran–Metal Nanostructured Substrates with Ag and Au@SiO2 Nanoparticles Deposited in Nanohole Arrays for Surface-Enhanced Fluorescence and Trace Detection of Metal Ions

The fluorescence intensity of the ring-opened merocyanine (MC) form of spiropyran can be enhanced by metal nanostructures. However, direct contact between spiropyran and the metal results in fluore...