“…Examples of bioreceptors include antibodies [ 138 ], aptamers [ 139 ], enzymatic bioreceptors, proteins, and nucleic acids. SPR fiber-based sensors have been applied for detection of pathogens, such as viruses [ 51 , 140 ], bacteria [ 141 ], biomarkers of medical conditions [ 43 , 50 , 142 , 143 ], study of DNA and DNA-protein interactions [ 144 , 145 ], and detection of bio-hazardous compounds [ 146 , 147 , 148 ]. However, even with its high sensitivity, SPR sensors cannot be successfully applied for a single molecule detection, unlike other optical resonance phenomena such as Whispering Gallery Mode [ 149 , 150 ], which typically exhibit much higher resolution.…”