Nanoantenna and uses thereof for biosensing

Abstract

A metal nanoantenna for use in a biosensing device is disclosed. The metal nanoantenna is arranged to exhibit at least two particle plasmon resonances or surface plasmon resonances (SPRs). The nanoantenna is for use in a sensor and allows detection at low concentration of biological components. In one aspect, the nanoantenna can have an asymmetric structural configuration and spectrally separated resonances. In one aspect, there is a location in its structure providing local electromagnetic field enhancement at all of the SPRs. The metal nanoantenna can be used for background free measuring of a quantity of a biological component.

1 . A nanoantenna for use in a luminescent biosensing device adapted to measure a quantity of a biological component comprising a label, the nanoantenna being arranged to exhibit at least two particle plasmon resonances or surface plasmon resonances (SPRs), and at least one of the resonances being able to excite the label by a two-photon absorption process. 
     
     
         2 . The nanoantenna according to  claim 1 , further comprising a crossed dimer structure. 
     
     
         3 . The nanoantenna according to  claim 2 , wherein the dimer structure comprises two arms having respective long axis forming an angle smaller than 90° with respect to each other. 
     
     
         4 . The nanoantenna according to  claim 2 , wherein the dimer structure comprises two arms having respective long axis of different length. 
     
     
         5 . The nanoantenna according to  claim 1 , further comprising at least one ligand for binding to a part of the antenna. 
     
     
         6 . The nanoantenna according to  claim 1 , wherein the nanoantenna is made of metal, and the label is photoluminescent. 
     
     
         7 . The nanoantenna according to  claim 1 , wherein the label has a predetermined emission frequency, and at least one of the resonances is able to couple to this emission frequency. 
     
     
         8 . A luminescent biosensor comprising:
 a nanoantenna according to  claim 1 ;   an excitation radiation source configured to generate a signal at one frequency of the at least two surface or particle plasmon resonances (SPRs) of the nano-antenna; and   a detector configured to detect a signal at the other frequency among the two surface or particle plasmon resonances (SPRs) of the nano-antenna.   
     
     
         9 . A substrate comprising a detection surface at the vicinity of which a quantity of biocomponents are present, and at least one nanoantenna according to  claim 1  formed on the substrate. 
     
     
         10 . The substrate according to  claim 9 , further comprising an array of nanoantennas according to  claim 1 . 
     
     
         11 . A luminescent biosensor comprising:
 a substrate according to  claim 9 ;   an excitation radiation source configured to generate a signal at one frequency of the at least two surface or particle plasmon resonances (SPRs) of the nano-antenna; and   a detector configured to detect a signal at the other frequency among the two surface or particle plasmon resonances (SPRs) of the nano-antenna.   
     
     
         12 . A method of measuring a quantity of a biological component comprising using the nanoantenna according to  claim 1 . 
     
     
         13 . A method of determining an analyte with a label in a fluid sample using a nanoantenna according to  claim 1 , the method comprising:
 generating a radiation signal at one frequency among the two surface or particle plasmon resonances (SPRs) of the nanoantenna for pumping the label through a two-photon absorption process; and   detecting a luminescence radiation signal emitted by the label at a frequency which coincides with the other of the at least two surface or particle plasmon resonances (SPRs).   
     
     
         14 . The method of  claim 13 , wherein the label has an absorption band in the UV or visible part of the spectrum. 
     
     
         15 . The method of  claim 13 , further comprising enhancing the emission of the label by coupling this emission to a surface or particle plasmon resonance (SPR) at one of the frequencies of the at least two frequency resonances of the nanoantenna, the at least two surface or particle plasmon resonances having substantially different values. 
     
     
         16 . The method of  claim 13 , wherein the method uses a substrate structured with areas in which field enhancement is different and also uses labels with different photon absorption cross sections, the method further comprising simultaneous analysis of multiple analytes. 
     
     
         17 . A method of determining an analyte with a label in a fluid sample using a nanoantenna, the nanoantenna being configured to exhibit at least two particle plasmon resonances or surface plasmon resonances (SPRs), the method comprising:
 generating a radiation signal at one frequency among the two surface or particle plasmon resonances (SPRs) of the nanoantenna for pumping the label through a two-photon absorption process; and   detecting a luminescence radiation signal emitted by the label at a frequency which coincides with the other of the at least two surface or particle plasmon resonances (SPRs).   
     
     
         18 . An apparatus for determining an analyte with a label in a fluid sample using a nanoantenna, the nanoantenna being configured to exhibit at least two particle plasmon resonances or surface plasmon resonances (SPRs), the apparatus comprising:
 means for generating a radiation signal at one frequency among the two surface or particle plasmon resonances (SPRs) of the nanoantenna for pumping the label through a two-photon absorption process; and   means for detecting a luminescence radiation signal emitted by the label at a frequency which coincides with the other of the at least two surface or particle plasmon resonances (SPRs).   
     
     
         19 . The apparatus according to  claim 18 , wherein the nanoantenna is made of metal, and the label is photoluminescent. 
     
     
         20 . The apparatus according to  claim 18 , wherein the label has a predetermined emission frequency, and at least one of the resonances is able to couple to this emission frequency.