Real time (label-free) detection and sizing of single protein molecule at its natural state is “holy grail” in biosensing
field. This non-destructive technique is useful for predicting the dangerous diseases at very early-stage. Herein, we
report the synthesis and characterization of efficient nanoplasmonic antennas, which could be useful to fabricate an
ultrasensitive nanoplasmonic-whispering gallery mode hybrid microresonator for the real time detection and sizing of
single protein molecule. This hybrid microresonator could be easily converted as an ultrasensitive single molecule
biosensor by anchoring suitable anti-bodies on the surface of the plasmonic nanoantenna.