Method for high-resolution detection of nanoparticles on two-dimensional detector surfaces
View Patent ↗The invention relates to a surface plasmon resonance spectrometer comprising a radiation source that emits substantially monochromatic radiation, a sensor surface, an optical arrangement for lighting the sensor surface by the radiation emitted from the radiation source such that surface plasmons can be created in the sensor surface, a detector having a plurality of image elements and observation optics for depicting the radiation reflected by the sensor surface on the detector, characterized in that the resolution capability of the observation optics and of the detector is larger than the resolution that can be obtained by the deflection-limited radiation source.
1. A surface plasmon resonance microscope, comprising
a radiation source emitting essentially monochromatic radiation,
a sensor surface reflecting said essentially monochromatic radiation with a reflectivity to obtain a reflected radiation with an intensity,
an optical assembly for illuminating said sensor surface with said radiation emitted by said radiation source in such a way that surface plasmons are generated in said sensor surface,
a detector with a plurality of detector elements detecting said intensity of said reflected radiation, and
an optical assembly for imaging said radiation reflected by said sensor surface on said detector
wherein
said resolution of said observing optical assembly and of said detector are higher than the diffraction-limited resolution which can be obtained with the radiation source achievable under classical conditions,
a change of said reflectivity caused by a particle at said sensor surface is observed,
the time dependency of said intensity in the range of the image of the particle is measured to quantify the signal of a particle, wherein the bonding of the particle at the sensor surface causes a saltatory intensity change at the corresponding image points, and
the signal is normalized with respect to a reference image which is obtained by calculating the average image over a period of time before the particle is bound.
2. A surface plasmon resonance microscope according to claim 1 , and further comprising a sensor surface in Kretschmann-arrangement.
3. A surface plasmon resonance microscope, comprising
a super luminescence diode forming a radiation source emitting essentially monochromatic radiation,
a sensor surface reflecting said essentially monochromatic radiation with a reflectivity to obtain a reflected radiation with an intensity,
an optical assembly for illuminating said sensor surface with said radiation emitted by said radiation source in such a way that surface plasmons are generated in said sensor surface,
a detector with a plurality of detector elements detecting said intensity of said reflected radiation, and
an optical assembly for imaging said radiation reflected by said sensor surface on said detector
wherein
said resolution of said observing optical assembly and of said detector are higher than the diffraction-limited resolution which can be obtained with the radiation source achievable under classical conditions,
a change of said reflectivity caused by a particle at said sensor surface is observed,
the time dependency of said intensity in the range of the image of the particle is measured to quantify the signal of a particle, wherein the bonding of the particle at the sensor surface causes a saltatory intensity change at the corresponding image points, and
the signal is normalized with respect to a reference image which is obtained by calculating the average image over a period of time before the particle is bound.
4. A surface plasmon resonance microscope according to claim 1 , wherein said sensor surface is coated with a gold layer.
5. A surface plasmon resonance microscope according to claim 1 , and further comprising means for establishing a contact between observed particles and the sensor surface.
6. A surface plasmon resonance microscope according to claim 1 , wherein said sensor surface is a surface with a strong change of said reflectivity generated by periodic structures enabling plasmon excitation.
7. A surface plasmon resonance microscope according to claim 1 , wherein said sensor surface is an antireflection coated glass or crystal surface with a strong change of said reflectivity upon binding particles.
8. A surface plasmon resonance microscope according to claim 1 , wherein said sensor surface is a surface with metallic nanoparticles with a strong change of said reflectivity upon binding particles enabling an excitation of localized plasmon resonance at the wavelength of said radiation source.
9. A surface plasmon resonance microscope according to claim 1 , wherein said sensor surface is an optical multi-layer structure where surface plasmon resonance can be excited.
10. A surface plasmon resonance microscope, comprising
a radiation source emitting essentially monochromatic radiation,
a sensor surface reflecting said essentially monochromatic radiation with a reflectivity to obtain a reflected radiation with an intensity,
an optical assembly for illuminating said sensor surface with said radiation emitted by said radiation source in such a way that surface plasmons are generated in said sensor surface,
a detector with a plurality of detector elements detecting said intensity of said reflected radiation, and
an optical assembly for imaging said radiation reflected by said sensor surface on said detector
wherein
said resolution of said observing optical assembly and of said detector are higher than the diffraction-limited resolution which can be obtained with the radiation source achievable under classical conditions,
a change of said reflectivity caused by a particle at said sensor surface is observed,
the time dependency of said intensity in the range of the image of the particle is measured to quantify the signal of a particle, wherein the bonding of the particle at the sensor surface causes a saltatory intensity change at the corresponding image points,
the signal is normalized with respect to a reference image which is obtained by calculating the average image over a period of time before the particle is bound
said detector is a Charge Coupled Device for detection of a plurality of time subsequent intensity signals for each pixel, and
processing means are provided adapted to generate time average values for the reduction of shot noise.
11. A surface plasmon resonance spectroscope according to claim 1 , wherein said bound particle causes a saltatory local change of the reflectivity in the vicinity of the binding point providing the measuring signal, whereby the position, as well as point in time of the signal appearing are not previously known and are to be found during the detection procedure.
12. Use of a surface plasmon resonance microscope according to claim 1 in virologic research, with the detection of viruses in public areas or in highly sensitive clinical diagnostics.
13. Method for the optical detection of individual nano particles on two-dimensional sensor surfaces by means of surface plasmon resonance spectroscopy, comprising the steps of:
(a) illuminating said sensor surface with radiation from a monochromatic radiation source in such a way that surface plasmons are generated in said sensor surface,
(b) introducing particles for observation on said sensor surface or in an immediate near range of said sensor surface, and
(c) detecting said radiation from said sensor surface with a detector with a plurality of detector elements,
wherein
(d) said particles are observed with a resolution which is higher than the diffraction- limited resolution obtainable by optical microscopy with said radiation source,
(e) said change of said reflectivity which is caused by a particle can be observed at said sensor surface,
(f) the time dependency of said intensity in the range of said image of said particle is measured to quantify said signal of a particle, wherein the bonding of said particle at said sensor surface has a saltatory intensity change at the corresponding image points, and
(i) said signal is normalized with respect to a reference image which is obtained by calculating the average over a period of time before said particle is bound.