Ultrabright fluorescent nanoconstructs as universal enhancers

A fluorescent nanoconstruct comprising:

• a plasmonic nanostructure having at least one localized surface plasmon resonance wavelength (λLSPR) between 400 nm and 1000 nm;
• at least one spacer coating;
• and
• at least one fluorescent agent having a maximum excitation wavelength (λEX);
• wherein the plasmonic nanostructure is coated with the at least one spacer coating;
• wherein the at least one of the spacer coating is conjugated with the at least one fluorescent agent;
• wherein the plasmonic nanostructure comprises gold or a silver coated gold;
• wherein the spacer coating comprises a siloxane network;
• wherein the spacer coating is on the nanostructure and has a thickness of about 0.5 nm to about 20 nm;
• wherein the fluorescent nanoconstruct has a fluorescent intensity that is at least 500 times greater than a fluorescent intensity of the at least one fluorescent agent alone;
• and
• wherein a wavelength difference between the at least one λLSPR and the λEX is less than 75 nm.