Drug detection via surface enhanced Raman spectroscopy

Abstract

The present invention relates to a method for determining an analyte using surface enhanced RAMAN spectroscopy and to a device which is suitable for this purpose.

Claims

1. A kit for determining an analyte in a sample comprising: (a) a sampling device configured for taking up a sample containing an analyte, wherein the sampling device comprises a sample matrix; and (b) an analysis device, comprising: a first region which is configured for introducing the sampling device; and a second region which is configured for detecting the presence and/or amount of the analyte in said sample via surface enhanced Raman spectroscopy, wherein said regions are interconnected by at least one processing stage which is located downstream from the sample matrix with respect to an intended flow direction of a fluid and which processing stage makes it possible to process the fluid which contains an analyte eluted from the sample matrix while the fluid and the analyte contained by the fluid are passed from the first region to the second region within the analysis device.

2. The kit of claim 1, wherein the sampling device comprises a volume indicator.

3. The kit of claim 2, wherein the sample matrix of the sampling device comprises an absorptive material configured to absorb the analyte-containing sample and to release it upon contact with an eluent and/or mechanical compression.

4. The kit of claim 1, wherein the sampling device comprises at least two separate parts, wherein the first part comprises the sample matrix and the second part comprises an eluent for eluting the analyte from the sample matrix.

5. The kit of claim 1, wherein the analysis device comprises a microfluidic structure.

6. The kit of claim 1, wherein the second region comprises a hollow-core optical fiber.

7. The kit of claim 6, wherein the hollow-core optical fiber is coated on its inside surface with a SERS-active coating, the coating comprising SERS-active nanoparticles.

8. The kit of claim 6, wherein the hollow-core optical fiber is coated on its inside surfaces, and wherein the second region is configured to receive the analyte-containing sample in a hollow core of the hollow-core optical fiber.

9. The kit of claim 1, further comprising: a radiation source for generating monochromatic light; a detector for detecting inelastically scattered radiation; and optics for directing the radiation.

10. The kit of claim 9, wherein the radiation source includes laser radiation.

11. The kit of claim 1, wherein the analysis device further comprises a housing, wherein at least one of the sampling device and the analysis device comprises an eluent and at least one of the sampling device and the analysis device comprises SERS-active particles.

12. The kit of claim 11, wherein the eluent present in the sampling device and/or in the analysis device comprises SERS-active nanoparticles dispersed therein.

13. The kit of claim 11, wherein the second region comprises SERS-active nanoparticles, including dry SERS-active nanoparticles or a dispersion of SERS-active nanoparticles.

14. A method for detecting an analyte in a sample, comprising: (a) receiving a sample containing an analyte via a sampling device comprising a sample matrix and an eluent for eluting the analyte from the sample matrix; (b) introducing the sampling device into an analysis device, comprising at least a first and a second region, wherein the first region is configured for introducing the sampling device and the second region is configured for detecting the analyte in said solution; (c) transferring the analyte in a fluid from the first region via at least one processing stage which processing stage is located downstream from the sample matrix with respect to a flow direction of the fluid and in which processing stage the fluid and/or the analyte transferred in the fluid are processed while the fluid and the analyte transferred in the fluid are passed to the second region of the analysis device; and (d) determining the presence or/and amount of the analyte in the second region via surface enhanced Raman spectroscopy (SERS).

15. The method of claim 14, wherein the sample matrix of the sampling device comprises an absorptive material configured to absorb the analyte-containing sample and to release it upon contact with an eluent and the analysis device comprises a microfluidic structure.

16. The method of claim 14, wherein the analyte comprises one or more of cannabis, synthetic cannabinoids, ketamines, cocaine, heroin, methadone, methamphetamines, and a prescriptive drug.

17. The method of claim 14, wherein the sample comprises sweat, saliva, urine, or blood.

18. The method of claim 14, wherein the sample volume is between 30 μl to 150 μl.

19. The method of claim 14, wherein the eluent present in the sampling device and/or in the analysis device comprises SERS-active nanoparticles dispersed therein.

20. The method of claim 14, wherein the second region of the analysis comprises a hollow-core optical fiber coated on its inside surfaces with a SERS-active coating, and that is configured to receive the analyte-containing sample in its hollow core.

Description

(1) The invention will be described in greater detail by way of the following drawings and examples.

(2) In the figures it is shown:

(3) FIG. 1 a schematic basic structure of an example device according to the present invention for the determination of an analyte using SERS;

(4) FIG. 2A a combination of a sampling device and a microfluidic analysis device before contacting with an eluent;

(5) FIG. 2B a combination of a sampling device and a microfluidic analysis device after contacting with the eluent;

(6) FIG. 3A a microfluidic device comprising a hollow core optical fiber before contacting with an eluent according to a further embodiment of the present invention;

(7) FIG. 3B the microfluidic analysis device according to FIG. 3A after contacting with an eluent;

(8) FIG. 4A, B, C a two-part sampling device with a part for taking up the sample including a sample matrix and SERS particles in a mixing container;

(9) FIG. 5 introduction of a sampling device into an elution container with SERS reservoir serving as an analysis device;

(10) FIG. 6 a schematic direct reading of the sampling device according to FIG. 4;

(11) FIG. 7A, B, C a reading of the analysis device of FIG. 5;

(12) FIG. 8A insertion of a two-part sampling device including a sample matrix and an elution container into a microfluidic analysis device;

(13) FIG. 8B a filling of the microfluidic analysis device according to FIG. 8A;

(14) FIG. 8C a microfluidic analysis device including a hollow core optical fiber;

(15) FIG. 9A, B functionalization of the SERS-particles with anti-bodies; and

(16) FIG. 10 further details in connection with an example embodiment comprising a hollow core optical fiber.

FIGURES

FIG. 1

(17) Basic structure of a device according to the invention for the determination of an analyte using SERS comprises:

(18) a housing of the analysis device 1,

(19) a sampling device 2,

(20) a microfluidic analysis device 3,

(21) a reservoir containing an eluent (separate region of the analysis device) 4,

(22) a laser 5,

(23) an optical fiber 5a, 5b (or any other optical guidance means or optical waveguide)

(24) a filter 6,

(25) a filter 7,

(26) a CCD device 8,

(27) a control computer 9, and

(28) a display/operating unit 10.

(29) The housing of the analysis device 1 is connected with the sampling device 2 and they also cover the microfluidic analyses device 3.

(30) Moreover, the reservoir 4 is attached to the housing of the analysis device 1.

(31) The laser 5 is optically connectable or connected (as shown in FIG. 1) with a specific optical coupling of the analysis device 1 and the laser beam excited by the laser 5 passes a filter 6 before entering the optical coupling of the analysis device 1.

(32) The laser 5 is guided by means of optical waveguides 5a, 5b, wherein one optical waveguide 5a is provided for sending from the laser 5 to the microfluidic analysis device 3 and from the microfluidic analysis device 3 to the filter 7 by means of another optical waveguide 5b.

(33) The control computer 9 is connected with the laser 5 and also connected with the display and operating unit 10. By means of the display and the operating unit 10 specific results are operating options may be displayed and also an user input can be done via the display or specific button, with which the control computer 9 can be operated.

(34) By means of the CCD camera 8 the outcoming optical signal out of the analysis device 1 is routed via the filter 7 to the CCD camera 8.

(35) The optical analysis of the CCD signal 8 is done via the control computer 9.

(36) As a suitable laser module with a fiber coupled semi-conductor laser (continuous wave (CW) with a wavelength of 785 nm (NIR) and a controllable laser power of up to 200 mW may be used. Such a laser is beneficial as it enables on the one hand a good fluorescence avoidance and a spectral sensitivity of the detector on the other hand.

(37) Also, in a further embodiment a semi conductor laser in the UV-range may be used. As long as the wavelength is significantly below 300 nm, noise may be avoided by auto fluorescence radiation of the sample. Furthermore, the signal intensity of the Raman radiation is increased with reduced wavelength. Both effects lead to a better signal-to-noise ratio.

(38) The wave guiding within the device is realized with multi model-optical waveguides.

(39) Such an optical waveguide may have a quartz glass core and sheath and may be coated with a polymer protection sheath.

(40) The core diameter is at least 300 μm, the numerical aperture is typically NA 0.22.

(41) For coupling of the laser beam into the optical waveguide for example a spherical lens or a rod lens may be used or an arrangement of aspherical lenses.

(42) The “inlet” filter 6 is used for preparation of the laser beam before coupling and sending into the sample. Unwanted wavelengths are removed by means of a band pass filter with narrow band width (background-removal).

(43) The filtered laser signal is then focused with a lens arrangement into the measurement chamber of the test cassette as for example shown in FIG. 8B or into a further waveguide (for example FIG. 8C).

(44) Within the analysis device 1 an optimized excitation radiation may be focused with a lens arrangement directly into the measurement chamber of the test cassette as shown in for example FIG. 2B and FIG. 7. For increasing the results of the Raman-scattered radiation, the measurement chamber may be reflective on the inside and/or have a concave shape.

(45) In further embodiment, the laser radiation may be coupled by means of a optical hollow fiber. Here, coupling optics or passive reflectors and/or tilted mirrors may be used.

(46) There may be an optical filter module for the Raman scattering.

(47) Within the test cassette excited scattering may be guided by means of suitable optics to the receiving waveguide 5a of the reader. The optics may be part of the test cassette or also integrated in the analysis device or the reader.

(48) The scattering may be guided by means with the receiving waveguide to the filter 7 and by means of e.g. a notch filter, the unwanted part of the Rayleigh scattering is filtered.

(49) The detector module 8 is especially suitable for a wavelength range of 800-1100 nm.

(50) There may be a slit mask for vignetting the radiation (ca. 10-20 μm slit width), a concave collimator-mirror, an optical diffraction grating and an optical assembly for focusing on the CCD element 8.

(51) In a further embodiment the number of optical components may be reduced by using a cross-section converter instead of a slit mask and a concave blazed holographic grating.

(52) The CCD array element may have a higher sensitivity in the NIR range and for example a resolution of 2048×64 pixels (for example Hamamatsu S11510-1106).

(53) Alternatively, a so-called BT-CDD chip (back-thin) may be used to achieve a higher quantum efficiency.

(54) For improving the signal-to-noise ratio further, the CCD element may be thermo-electrically cooled with a Peltier element.

(55) The control unit 9, which is connected with the CCD element 8 digitalizes the signals from the CCD element 8 and processes an analysis result.

(56) By means of a signal comparison with available target-spectra (“fingerprints”) for the analytes of interest, a fast and specific analysis may be performed.

FIGS. 2A and B

(57) A combination of sampling device and microfluidic analysis device before (FIG. 2A) and after (FIG. 2B) contacting with eluent, comprising

(58) a sampling device 2;

(59) microfluidic analysis device 3 containing a separate region 4, which comprises an eluent with SERS active nanoparticles dispersed therein,

(60) microfluidic mixing path 12;

(61) microfluidic valve 13 for allowing a balance of pressure;

(62) detection chamber 14 (second region of the microfluidic analysis device).

(63) FIG. 2A illustrates the introduction of a sampling device into a microfluidic analysis device. The sample matrix wetted with a saliva sample is pressed into a washing chamber of the microfluidic analysis device 3 and insulated on the side 11. By means of a subsequent manual compressing of a reservoir 4, the eluent contained therein is set free and a pumping effect for transporting such eluent through the channels 12 of the microfluidic analysis device is produced. A microfluidic valve 13 allows a balance of pressure. The eluent may contain SERS active particles (*). From this pumping effect, the sample matrix is flushed with the eluent and thus the sample/analyte is dissolved in the eluent and mixed while being transported through fluidic channels 12 to the detection chamber 14, i.e. the optical interface of the spectroscopic evaluation. The detection chamber may contain SERS active particles.

(64) FIG. 2B shows the microfluidic analysis device after compression of the reservoir. The eluent now washes over the sample matrix. SERS active nanoparticles (*) are homogenously dispersed in the eluent in which the analyte is dissolved.

FIGS. 3A and B

(65) Microfluidic analysis device comprising a hollow core optical fiber 15. The optical hollow fiber comprises a hollow core 16, a glass capillary 17 and optionally a casing 18. The capillary 17 can additionally contain on its inside surface a coating with SERS active nanoparticles 19. The coupling and uncoupling of the laser and Raman radiation, respectively, as illustrated in FIG. 3B is achieved by deflection mirrors 20 or a corresponding positioning of the optical fiber.

FIGS. 4A and 4B

(66) Two-part sampling device with a part for taking up the sample including the sample matrix 401 and a mixing container 402. A saliva sample is taken up using the part including the sample matrix 401. Subsequently, the part including the sample matrix 401 is introduced into the mixing container 402 and manually compressed therein until it is in lock position R1. By this procedure, the saliva sample is sent through at least one sieve-like intermediate base and brought to a mixing zone 404 which contains dried SERS nanoparticles 405.

(67) By subsequent manual shaking, the SERS particles are dispersed in the sample.

(68) By mixing of the substances by manual shaking, a good dispersion of all substances may be achieved.

(69) The mixing of the substances may be achieved by manual shaking of the whole analysis device. It may also be achieved by shaking the cassette.

(70) The analysis device is then inserted in the receiving portion of the reading device as shown in FIG. 6 and FIG. 7.

(71) The receiving portion comprises a magnetic coil 720 as shown in FIG. 7C. It will provide a varying magnetic field, which will cause movement of the magnetic particles within the solution and thus cause a homogeneous mixing.

(72) For reliable dispersing of dried SERS-particles or a coating of dried SERS-particles with a low amount of saliva, the following structure and procedure may be provided:

(73) The extraction container may comprise a mixing zone 404, which comprises a soluble coating with SERS particles as further shown in FIG. 4B and FIG. 4C.

(74) In the mixing zone there are freely moveable, magnetic particles or miniature mixing spheres or objects 406.

(75) These mixing objects are excited by an external magnetic field 407, which can be arranged in the receiving portion of the reading device for a circular or elliptical movement within the mixing zone 404.

(76) The detection area is equipped with inlet optics 409 and outlet optics 411.

(77) A partition wall 410 is separating the mixing zone from the detection zone.

(78) The partition wall 410 may comprise a reflective coating directed to the detection zone and thus may act as a mirror.

(79) Furthermore, this partition wall 410 may be concave.

(80) The function of the procedure shown in FIG. 4B, 4C is as follows:

(81) The saliva, which has been collected with the sampling device 401 is transferred into the mixing chamber 404 by compressing it to position R1 (shown in FIG. 4C).

(82) The sampling container 402 is then inserted into the receiving portion of the reading device.

(83) Especially by means of the optical sensor 710 as shown in FIG. 7B, the correct positioning of the sampling container within the receiving portion is checked.

(84) By means of magnetic excitation, the magnetic particles 406 in the mixing chamber 404 are brought into movement, which enhances the release of the SERS coating 405 and a mixing of the SERS particles with the saliva sample 403 brought into the mixing chamber 404.

(85) By means of the laser radiation for excitation of the Raman effect by means of the optical waveguide 408 and the optical device 409, which may comprise an inlet lens, the laser radiation is led into the detection chamber 413.

(86) The so generated scattering radiation is trapped with the optic module 411, which is here comprising a spherical lens.

(87) By means of the optical module 411 the generated scattered radiation is coupled into the receiving optical waveguide 412.

FIG. 5

(88) Introduction of a sampling device 501 into an elution container with SERS reservoir serving as an analysis device. The elution container includes a separate reservoir 506 that is filled with a liquid (the eluent) comprising SERS active particles 507 dispersed therein. In the left part of the figure, the sampling device 501 including a sample matrix soaked with a liquid sample is introduced into a first region of the elution container and manually compressed until it is in lock position R1 to release the liquid sample through a sieve-like intermediate base 503 into a mixing chamber 509 of the elution container. Upon further pressing the sampling device 501, the sieve-like intermediate base 503 is placed into lock position R2 as shown in the right part of the figure. The intermediate base contains a mandrel 508, which opens the reservoir 506 when in position R2. By subsequent manual shaking, the solution (eluent) contained in the reservoir 506 is thus mixed with the sample. Additionally, the solution (eluent) rinses the sample matrix and thus flushes out any remaining analyte.

FIG. 6: Direct Reading of the Sampling Device of FIG. 4

(89) For the analysis, the sampling device of FIG. 4 is placed in a holder 601 of the reading device. Coupling and uncoupling of laser and Raman radiation are achieved by optical fibers 602.

FIG. 7: Reading of the Analysis Device of FIG. 5

(90) The elution container of FIG. 5, serving as an analysis device, is placed in a holder 701 of the reading device. The reservoir includes a defined volume of eluate comprising the analyte-containing sample dissolved in the eluent with SERS active particles dispersed therein. Coupling and uncoupling of laser and Raman radiation are achieved by optical fibers.

(91) FIG. 7B shows the reading of the analysis device as shown in FIG. 7, with an additional, optional detail.

(92) While placing the elution container, serving as analysis device in the holder 701 of the reading device, this placement may be assisted by the analysis device and the respective geometries.

(93) The container may be in the shape of a cassette, especially a disposable cassette.

(94) There may be a guiding structure, which my allow insertion only in one possible way to create a so-called “fool-proof” solution.

(95) The opening of the receiving portion of the analysis device may be protected by means of an optical lid (not shown). By means of this optical lid, unwanted optical influence from the outside may be prevented.

(96) To ensure a correct coupling an additional sensor 710 may be provided.

(97) By means of the sensor 710 the correct positioning of the cassette within the holder 1 may be checked.

(98) For a correct coupling of the laser beam it is important that the cassette has reached a defined end-position within the holder 1.

(99) In the shown embodiment, this is realized by means of an optical sensor 710.

(100) However, any other sensor like an electrical switch, a magnetic sensor, an electrical sensor or the like may be used.

(101) In a possible further embodiment of the test cassette as shown in FIG. 4 and FIG. 5 the mixing of the minimal volumes of for example saliva with a SERS solution may be enhanced.

(102) A mixing of saliva with the SERS solution is beneficial for the detection of the analytes.

(103) For this reason, the receiving portion may be equipped with a magnetic coil 720 (cf. FIG. 7C).

(104) By using magnetic microparticles or nanoparticles in the SERS-solution and a magnetic induced movement, a mixing effect may be achieved. Furthermore, by using the magnetic particles and the coil, information about the viscosity of the fluid can be obtained by the inverse effect: The particles still in movement will induce a voltage in the coil 720, wherein depending on the viscosity of the fluid, a voltage proportional to the residual movement of the magnetic particles can be measured. The higher the viscosity, the lower the residual particle movement, the lower induced voltage.

(105) Furthermore, there may be optical collimators in any of the described embodiments which will allow an incoupling or outcoupling of the laser beam into the optical waveguides 5a, 5b (FIG. 1).

(106) As a further point, SERS particles with identical characteristics are hard to reproduce. Therefore, a receiving portion may be equipped with a code reader to read out production-lot specific parameters from the test cassette, which will be inserted into the receiving portion of the holder 1. Such code readers may be for example RFID readers, barcode readers, QR-code readers or the like.

(107) If there is no test cassette in the receiving portion then the receiving portion opening will be protected by means of a protection mechanism.

(108) Such protection mechanism may be embodied with a spring activated mechanism and a sealing.

(109) By this protection mechanism the intake of contaminations of any kind may be avoided.

FIG. 8A

(110) Insertion of a two-part sampling device including a sample matrix and an elution container into a microfluidic analysis device. The sampling device 801 containing an eluate of the analyte with SERS active particles dispersed therein is placed in a sealed fitting 803 of the microfluidic analysis device 802. By means of a mandrel 804 provided in the analysis device, the base of the elution container is then opened at a predetermined breaking point.

FIG. 8B

(111) Filling of the microfluidic analysis device: by further pressing of the sampling device 805, the eluate is transferred into the microfluidic analysis device, optimally mixed in mixing channels 806, and transported to the detection chamber 807. This chamber can be coated with SERS nanoparticles (*). A balance of pressure is achieved by a microfluidic valve 808.

FIG. 8C

(112) Microfluidic analysis device including a hollow core optical fiber 810. The optical fiber can contain on its inside surface a SERS active coating, preferably with SERS active nanoparticles, whereby the Raman effect is additionally enhanced.

(113) In any of the above described devices a kit may be used, wherein the eluent present and the sampling device and/or in the analysis device comprises SERS-active nanoparticles dispersion therein.

(114) Especially, reference is made to the embodiments shown in FIG. 2A and FIG. 4.

(115) The saliva sample, which shall be analyzed, is collected with an absorbent sampling device, especially a cotton bud, cotton swab or a Q-Tip or the like.

(116) The extraction of the saliva from the sampling device may be enhanced and supported by means of elution.

(117) The elution means or eluent is provided therefore in a reservoir of the sampling device or in the analysis device.

(118) For freeing the eluent preferably a manual action is necessary, for example pressing on the reservoir and thereby braking a seal.

(119) The movement of the eluent is shown in FIGS. 1, 2A, 4, 5 and 6.

(120) The eluent may comprise substances for treating the saliva sample.

(121) Moreover, the eluent may also comprise so-called SERS-nanoparticles.

(122) In connection and depending on the analyses to be detected, the particles may be made out of specific metals, sizes and characteristics and may be also chosen depending on the kind of analysis and also combined together with each other.

(123) Preferably, SERS-nanoparticles comprising gold or silver or being gold or silver may be used.

(124) This kind of SERS-particles has been reported to provide a very good enhancement in connection with the technology of the present invention.

(125) The particles may be spherical, which is however not mandatory.

(126) If the diameter of the particle chosen below, the wavelength of the excitation radiation. Typically, then the diameter then is chosen within a range of 50 to 200 nm.

(127) Moreover, the nanoparticles may be bound with linking molecules to specific antibodies. With this mechanism, specific target antigens (analytes) may be specifically trapped and detected.

(128) For characterization of the SERS-activity of the solution, the solution may also comprise control analytes.

(129) The eluent may also comprise magnetic particles.

(130) By means of the control analytes the shelf-live of the SERS-particles and whether or not the particles are still working can be detected.

(131) For example, the shelf-live of SERS-particles or SERS-substrates may be relatively short, for example it is reported that some SERS-particles only have a shelf-life of 60 days.

(132) By using magnetic particles and by using these particles for a mixing of the all components of the eluent and the solution, agglomeration of the nanoparticles may be avoided and a good dispersion of all components of the eluent can be achieved this way.

(133) As a general remark it shall be mentioned that the use of metallic SERS-nanoparticles may enhance the relatively weak Raman signals by the factor of 10.sup.4 up to 10.sup.6. This effect is primarily achieved by means of the excitation of the metallic surface plasmons, which are excited by the laser radiation.

(134) Thus, an electromagnetic interaction with the analyte molecules is achieved and an enhancement is provided.

(135) The molecules may be bound to the metal or in the close vicinity of the electromagnetic field of the nanoparticles.

(136) A clustering of nanoparticles may also provide better signals by creating so-called “hot-spots”.

(137) At 780 nm excitation radiation especially dimers with a size of around 80 nm are of interest.

(138) For the Raman signal enhancement especially size, shape and surface of the SERS-particles is important.

(139) The reproducibility of these parameters, however, may be difficult, especially from production lot to production lot.

(140) Consequently, it is therefore proposed in connection with this disclosure that a characterization of the SERS-activity by means of a control substance is done. Prior to the analyte detection itself, the Raman spectrum of the known reference substance is analyzed and detected and a self calibration is performed. By this, a good reproducibility of the detection may be guaranteed. Also, the accuracy of the overall system and process is significantly enhanced.

(141) Also, by a possible functionalization of the SERS-particles with anti-bodies selective target analytes may be bound.

(142) This is shown in FIGS. 9A and 9B.

(143) In FIG. 9A a silver SERS-particle 900 is shown. Bound to the particle 900 a linker 910 and a anti-body 920 is bound to the linker 910.

(144) An excitation with the laser L leads to a Raman signal or Raman response RA1.

(145) When adding an antigen 930, which is then bound to the anti-body 920 as shown in FIG. 9B, the laser excitation leads to a Raman response RA2.

(146) By this approach it becomes possible to detect very specifically different analytes and to adjust the SERS-solution to target analytes of interest.

(147) FIG. 10 shows further details in connection with an example embodiment comprising a hollow core optical fiber 1000, having a hollow core 1005 and an wall 1020 with an coating 1010 on its inside wall.

(148) In an embodiment, where the second region of the kit comprises a hollow-core optical fiber that may optionally be coated on its inside surface and that is configured to receive the analyte-containing sample in its hollow-core, the following points have been observed:

(149) For a total reflection the refractive index of the analyte-sample-solution (aqueous solution ca. 1.33) must be bigger than the refractive index of the quartz glass wall 1020 (ca. 1.46).

(150) To solve this specific aspect, substances that increase the refractive index, like glycerin paraffine oil or formazine may be added to the solution.

(151) In such a connection, the structure may be realized as follows (but not limited to this example):

(152) The test cassette may comprise a receiving portion with a seal for a wiper (see also FIG. 2A, reference no. 11 or for the sampling device (cf. FIG. 8A, reference no. 803).

(153) The eluent solution is either in the reservoir of the test cassette likewise the embodiment shown in FIG. 2A, reference no. 4, or in the mixing chamber of the sampling device according to the embodiment shown in FIG. 8a.

(154) In both cases the eluent provided in the reservoir may contain SERS-nanoparticles or SERS-clusters.

(155) In the embodiment shown in FIG. 10 a quartz glass fiber with a hollow-core is used.

(156) This fiber serves as microfluidic analysis chamber for the analyte solution but also as an optical waveguide for the incoming excitation laser radiation and the Raman radiation.

(157) For the desired total reflection the wall must have a lower refractive index than the filled core.

(158) At a refractive index of 1.46 for quartz glass the aqueous solution in the core is brought by means of additives like glycerin or paraffin oil or formazine to a refractive index of more than 1.46. Alternatively, a polymer fiber may be used with a refractive index of lower than 1.33, for example Teflon-AF.

(159) It is also possible that a hollow-core fiber is used with a second sheath (see also FIG. 3A, number 18), which uses a refractive index that is lower than the refractive index of the first sheath 17.

(160) Alternatively, a microstructured photonic crystal fiber may be used, which guides light not on the principle of inner total refraction but on the principle of photonic crystallic fibers/band gap fibers (PCF).

(161) In a further variant, especially as shown in FIG. 10, the fiber for the laser radiation and the receiving optical fiber are arranged perpendicular to a hollow fiber filled with analytes.

(162) The sheath of the hollow fiber works as an optical resonator.

(163) The SERS-solution close to the hollow fiber walls is then excited to Raman radiation.

(164) The optical module in the test cassette serves for condensing the excitation laser in the optical waveguide.

(165) This module may comprise a focus lens, a reflection mirror and a semi-permeable mirror.

(166) The latter may also be used for reflection of the scattered radiation within the hollow fiber and thus may serve as an enhancement element.

(167) The length of the optical waveguide may be adapted to the volume of eluent and analyte, so that at a minimal allowable filling of the hollow-core, the hollow-core is completely filled. The hollow fiber may comprise on its inner walls SERS-active coatings.

(168) At the end of the hollow fiber a spill over reservoir may be provided and also a water tight but air permeable seal for pressure equalization.

(169) The function may be described as follows:

(170) After taking a sample (e.g. of saliva) the wiper or the sampling device is inserted into the test cassette.

(171) Depending on the sampling device mechanism the eluent is freed and mixed with the saliva sample.

(172) By manually activating the reservoir or the sample device the solution is fed into the hollow fiber.

(173) A potential overrun is taken up with the waste reservoir and if a pressure equalization is needed, then the semi-permeable membrane, which is water-tight but air permeable will provide the pressure equalization.

(174) The laser excitation is focused either in or directed onto the hollow fiber and will generate the specific Raman scattering.

(175) This specific Raman scattering will then be focused with the specific optic elements (cf. see above in the already described embodiments) into the receiving optical waveguide of the analysis device and will then be processed by means of e.g. the controller 9 and the CCD device 8.