Abstract
A diffractometric sensing device for analyzing molecular interactions is described, the diffractometric sensing device comprising a transparent carrier medium, the carrier medium comprising a grating structure (42.1-42.5) with a plurality of consecutive surfaces or lines and a plurality of binding sites arranged thereon, the binding sites being configured to interact with one or more target molecules, wherein the grating structure is configured to diffract a portion of coherent light propagating in the carrier medium so as to produce a constructive interference signal at a light detector (4.1-4.4), the signal being dependent on molecular interactions at or in the vicinity of the binding sites. The invention offers more sensitivity, faster response, miniaturization, easy manufacturing and more applications compared to current diffractometric sensing devices.
Claims
1. A diffractometric sensing device (10, 20, 15) for analyzing molecular interactions, comprising: a three-dimensional transparent carrier medium (11, 21), the carrier medium (11, 21) being permeable to one or more target molecules and comprising a grating structure (12, 22) with a plurality of consecutive surfaces (13, 23) and a plurality of binding sites arranged thereon, the binding sites being configured to bind the one or more target molecules, wherein the grating structure (12, 22) is configured to diffract a portion of coherent light (2) propagating through the carrier medium (11, 21) so as to produce a constructive interference signal at a light detector (4), the signal being dependent on molecular interactions at or in the vicinity of the binding sites.
2. A diffractometric sensing device (30, 30.1, 30.2, 30.3, 30.4), for analyzing molecular interactions, the device comprising: a waveguide (31, 31.1-31.6, 35) confining the light in both transverse directions, with an electromagnetic field cross-section allowing for the light to interact with a grating structure (32) in a carrier medium with a plurality of consecutive lines or surfaces (33) and a plurality of binding sites arranged thereon, the binding sites being configured to bind one or more target molecules, wherein the grating structure (32) is configured to diffract a measurable portion of coherent light (P1, P2) propagating through the waveguide the signal being dependent on molecular interactions at or in the vicinity of the binding sites.
3. A diffractometric sensing device for analyzing molecular interactions, the device comprising: a waveguide arranged on a substrate (41.1, 41.2, 41.3, 41.4, 41.5, 41.6,41.7,41.8, 41,9, 41.10, 41.11, 41.12) and further comprising a light detector (4, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8) and a coherent light source (1, 1.1-1.10) with at least one (1.1, 1.2, 1.6; 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8) of the two being integrated on the same substrate (41.1, 41.2, 41,3, 41.4, 41.5, 41.6, 41.7, 41.8, 41.9, 41.10, 41.11, 41.12), further comprising a grating structure (42.1, 42.2, 42.3, 43.4, 42.5, 52.1, 52.2, 52.3, 52.4) in a carrier medium with a plurality of consecutive lines or surfaces and a plurality of binding sites arranged thereon, the binding sites being configured to bind one or more target molecules, wherein the grating structure is configured to diffract a portion of the evanescent field of the coherent light (1.3, 1.4, 1.5) propagating through the waveguide so as to produce a constructive interference signal at the light detector (4, 4.1, 4.2, 4.3, 4.4, 4.5, 4,6, 4.7, 4.8), the signal being dependent on molecular interactions at or in the vicinity of the binding sites.
4. A diffractometric sensing device according to claim 3, wherein both the light source (1.1, 1.2, 1.6) and the sensor (4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8) are integrated on the same substrate as the waveguide.
5. A holographic method (526, 651, 652) to lithographically create a coherent grating structure (522, 523, 524, 525) in a carrier medium with a plurality of consecutive lines or surfaces and a plurality of binding sites arranged thereon, the binding sites being configured to bind one or more target molecules, wherein the grating structure is configured to diffract a measurable portion of light, with the signal being dependent on molecular interactions at or in the vicinity of the binding sites.
6. A diffractometric sensing device (300) for analyzing molecular interactions, the device comprising: a grating structure (306) in a carrier medium integrated into a microwell plate (308) with a plurality of consecutive lines or surfaces (306) and a plurality of binding sites arranged thereon, the binding sites being configured to bind one or more target molecules, wherein the grating structure under illumination is configured to diffract a portion of light (P4) so as to produce a constructive interference signal captured by a light detector (303), the signal being dependent on molecular interactions at or in the vicinity of the binding sites.
7. The diffractometric sensing device (200, 300) according to claim 6 for analyzing molecular interactions, wherein the illumination of the grating structure is performed by the evanescent field of a totally internal reflected beam.
8. The diffractometric sensing device according to claim 1, wherein the surfaces or lines (13) of the grating structure are configured in a curved shape (12, 106, 206, 306, 42.1, 42.2, 42.3, 42.4, 42.5, 52.1, 52.2, 52.3, 52.4, 522, 523, 524, 525) to focus the diffracted portion of the coherent light into a diffraction limited focal spot captured by the detector (4).
9. The diffractometric sensing device according to claim 1, wherein the carrier medium (11, 21, 45) is made of a hydrogel or a mesoporous material or DNA scaffold or a 2 dimensional adlayer.
10. The diffractometric sensing device according to claim 1, wherein the diffracted light is focused by a lens (5) or observed in the farfield in terms of the Fraunhofer distance.
11. The diffractometric sensing device according to claim 1, wherein multiplexing is performed in a single compartment by having several grating structures (52.1, 52.2, 52.3, 52.4) with different binding sites immobilized on the grating structures and by configuring the different grating structures to diffract the light to a different location, which can be achieved by different spatial frequencies of the grating and/or by different locations of the gratings.
12. The diffractometric sensing device according to claim 1, with arrays of diffractive gratings consisting of binders including but not limited to peptides, DNA, RNA, lipids, antibodies, polysaccharides or protein fragments configured in such a way that the plurality of binding sites of each individual diffractive grating can be chosen to be chemically distinct from the plurality of binding sites of every other diffractive grating with the intention of optimally mapping the chemical complexity of the sample into a domain of lower complexity.
13. The diffractometric sensing device according to claim 1, wherein a coherent pattern formed by the binding sites arranged on the plurality of the consecutive surfaces of the grating structure is backfilled with another binder to tune the apparent affinity constant of the overall sensing device or normalize the appearing signal with a known concentration of analyte previously spiked into the sample to be measured.
14. The diffractometric sensing device according to claim 1, wherein an array of coherent patterns formed by the binding sites arranged on the plurality of the consecutive surfaces of the at least one grating structure is used for both real-time and endpoint molecular profiling of patient samples.
15. The diffractometric sensing device according to claim 14, wherein the obtained kinetic and end point data are compared by means of machine learning techniques to a large database of existing binding data linked to genetic and/or anatomic and/or clinical data of the corresponding patient or other patients.
Description
BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS
[0070] The herein described invention will be more fully understood from the detailed description given herein below and the accompanying drawings.
[0071] FIG. 1 shows an embodiment of a diffractometric sensing device;
[0072] FIG. 2 shows a further embodiment of a diffractometric sensing device;
[0073] FIG. 3 shows a further embodiment of a diffractometric sensing device;
[0074] FIG. 4 shows a further embodiment of a diffractometric sensing device comprising a waveguide;
[0075] FIG. 5 shows various embodiments of a waveguide usable for the diffractometric sensing device;
[0076] FIG. 6 shows various embodiments of a diffractometric sensing device with stacked waveguides;
[0077] FIG. 7 shows one embodiment of diffractometric sensing devices with arrangements wherein a waveguide and at least one of the light detector or the light source are arranged on a common substrate, wherein the grating structure comprises lines formed on a surface of the substrate;
[0078] FIG. 8 shows one embodiment of diffractometric sensing devices with arrangements wherein a waveguide and at least one of the light detector or the light source are arranged on a common substrate, wherein the grating structure comprises lines foi rued on a surface of the substrate;
[0079] FIG. 9 shows one embodiment of diffractometric sensing devices with arrangements wherein a waveguide and at least one of the light detector or the light source are arranged on a common substrate, wherein the grating structure comprises lines formed on a surface of the substrate;
[0080] FIG. 10 shows one embodiment of diffractometric sensing devices with arrangements wherein a waveguide and at least one of the light detector or the light source are arranged on a common substrate, wherein the grating structure comprises lines formed on a surface of the substrate;
[0081] FIG. 11 shows one embodiment of diffractometric sensing devices with arrangements wherein a waveguide and at least one of the light detector or the light source are arranged on a common substrate, wherein the grating structure comprises lines formed on a surface of the substrate;
[0082] FIG. 12 shows a measurement setup with a total internal reflection (TIR) arrangement comprising a diffractometric sensing device;
[0083] FIG. 13 shows an embodiment of an objective usable in a TIR configuration;
[0084] FIG. 14 shows one setup in the TIR configuration integrated into a standardized well-plate format;
[0085] FIG. 15 shows one setup in the TIR configuration integrated into a standardized well-plate format;
[0086] FIG. 16 shows principles of holographic lithography for diffractometric sensing;
[0087] FIG. 17 shows a possible application of the holographic lithography;
[0088] FIG. 18 shows components of a low noise measurement method as used for a coherent sensing technique;
[0089] FIG. 19 shows different arrangements of diffractometric binder arrays;
[0090] FIG. 20 shows a part of a diffractometric binder array;
[0091] FIG. 21 shows an illustration of employing a diffractometric reference pattern that uses a common element for the two binders such that the binder responsible for the signal in the case of a backfilled diffraction pattern can be determined;
[0092] FIG. 22 shows experimental real-time data obtained from a pilot study employing a set of 5 different binders profiling unmodified human serum;
[0093] FIG. 23 shows endpoints of the diffractometric molecular profiling approach. The endpoint responses are markedly different from traditional immunosignaturing since not only the immunome is profiled but the entire serum interactome; and
[0094] FIG. 24 shows comparative endpoint data obtained by traditional immunosignaturing approaches for the same set of binders.
DETAILED DESCRIPTION OF THE INVENTION
[0095] FIG. 1 shows an embodiment of a diffractometric sensing device 10 comprising a three-dimensional carrier medium 11 with a grating structure 12 arranged within the carrier medium 11. The grating structure 12 comprises a plurality of surfaces 13 which are consecutively arranged to each other. The surfaces 13 have a plurality of binding sites, e.g., receptors, antibodies, DNA (deoxyribonucleic acid), RNA (ribonucleic acid), peptides, aptamers, GPCRs (G protein-coupled receptors), proteins or DARPins (de-sign ankyrin repeat proteins), arranged thereon and configured to interact with tar-get molecules, such as ligands, antigens, DNA, RNA, proteins, peptides (binding sites and target molecules not being visible in FIG. 1). A light source generates coherent light 2 which propagates through the carrier medium 11. When passing the grating structure 12 with the target molecules bound to the binding sites on the sur-faces 13, a portion of the coherent light 2 is diffracted at the grating structure 12 with the target molecules and is directed to the diffraction-limited focal point 3 positioned at a light detector 4. The focal point intensity depends on the amount of tar-get molecules bound to the binding sites of the surfaces 13 and hence correlates to the binding affinities of the target. Therefore, it provides information on the binding event of the target molecules. The carrier medium 11 is transparent and permeable to the target molecules which are deposited into the carrier medium 11 before performing the diffractometric measurements. The configuration as shown in FIG. 1 allows to probe the target molecules in a dark field illumination setup. Due to the structure of the curved surfaces 13, no additional lenses are needed to focus the diffracted coherent light onto the focal point 3 at the detector 4. In the shown embodiment, the detector 4 is arranged within the carrier medium 11 which allows for a compact de-sign. The coherent light 2 is provided by a waveguide 1 butt-coupled to the carrier medium 11.
[0096] FIG. 2 shows a further embodiment of a diffractometric sensing device 20 comprising a three-dimensional carrier medium 21 with a grating structure 22 arranged within the carrier medium 21. The grating structure 22 comprises a plurality of planar surfaces 23 which are arranged parallel to each other. As for the embodiment shown in FIG. 1, the surfaces 23 have a plurality of binding sites arranged thereon and configured to bind target molecules. An external light source couples a plane wave of coherent light 2 which propagates through the carrier medium 21 and passes the grating structure 22 with the target molecules bound to the surfaces 23. A portion of the coherent light 2 is decoupled by scattering at the target molecules and gets diffracted towards an external light detector 4. Near-to-far-field transformation is performed by a lens 5 arranged between the grating structure 22 and the light detector 4. In this example the carrier is embedded in a well with two mirrors with angles of 45° to avoid background light on the detector 4.
[0097] FIG. 3 shows a further embodiment of a diffractometric sensing device 15, where the carrier medium 11 is situated on a transparent substrate 102, through which the grating structure 12 is illuminated. The coherent light 2 is focused into a diffraction-limited spot or point 3 upon binding of target molecules to the binding sites on the surfaces of the grating structure 12. In this example the diffracted light is collected with an objective 103.
[0098] FIG. 4 shows a further embodiment of a diffractometric sensing device 30 comprising a waveguide 31 confining the light in both transverse directions. The waveguide 31 comprises a sensing area with a grating structure 32 having a plurality of surfaces or lines 33 arranged within the waveguide 31 and forming a distributed Bragg reflector with periodicity or grating period Λ≈λ/(2N), with λ=light wavelength and N=effective refractive index of the grating in the waveguide. Binding sites are arranged on the surfaces or lines 33 and target molecules may interact with the target molecules such that light propagating through the waveguide 31 is reflected at the grating structure 32 with the signal intensity depending on the molecular interactions. After the sensing area, the waveguide 31 comprises an optical out-coupler 34 abut-ting the grating structure 32 and being in the shape of a tapered part 34 to avoid reflections. A light source 1 is arranged at one end of the waveguide 31. The diffractometric sensing device 30 further comprises a circulator 6 being arranged between the light source 1 and the grating structure 32 and configured to separate incoming coherent light (indicated by the arrow P1) from the portion of the incoming coherent light diffracted at the grating structure 32 (indicated by the arrow P2). The diffracted portion of the coherent light propagates through a waveguide 35 and is detected at a light detector 4.
[0099] FIG. 5 shows various embodiments of a waveguide confining the light in both transverse directions usable for the diffractometric sensing device, such as a tapered optical nanofiber 31.1, microstructure hollow fiber with a glass hanging core 31.2, a nanobore fiber 31.3, a fiber 31.4 with multiple nanobores, an on-chip ridge waveguide 31.5 and a slot waveguide 31.6
[0100] FIG. 6 shows various embodiments of a diffractometric sensing device with stacked waveguides, such as an embodiment of a diffractometric sensing device 30.1 with tapered optical fibers which are stacked in parallel, an embodiment of a diffractometric sensing device 30.2 with nanobore fibers which are stacked in parallel, an embodiment of a diffractometric sensing device 30.3 with tapered optical fibers which are stacked perpendicular to each other in two perpendicular directions, and an embodiment of a diffractometric sensing device 30.4 with tapered optical fibers which are stacked perpendicular to each other in three perpendicular directions. The high density of the fibers allows an effective sensing in the sample volume.
[0101] FIG. 7-11 show embodiments of diffractometric sensing devices with arrangements where the dark field illumination is provided by a planar waveguide. The surfaces or lines on which binding sites are arranged are designed to focus the light to a diffraction limited spot within the waveguide. The detector and/or the light source is or are integrated to the same substrate at the location of the diffraction-limited focal spot.
[0102] FIG. 7(a) shows an embodiment where the incoming coherent light is coming from a guided point source 1.1. The guided point source 1.1 may be a light scatterer which is illuminated by another light source. The light passes a grating structure 42.1 with target molecules. A portion of the light is diffracted at the grating structure 42.1 with the target molecules and directed towards a light detector 4.1. The light detector comprises an aperture 7.1 with an opening preferentially matching the spot size of the diffracted portion of the coherent light and the numerical aperture of the grating structure 42.1. The guided point source 1.1, the grating structure 42.1 and the light detector 4.1 are arranged on a common substrate 41.1, such that an integrated on-chip diffractometric sensing device is provided.
[0103] FIG. 7(b) shows a further embodiment where a grating structure 42.2 and a light detector 4.2 with an aperture 7.2 similar to the one as shown in FIG. 7(a) are arranged on a common substrate 41.2. The light source is a free space point source 1.2 arranged below the common substrate 41.2.
[0104] FIG. 7(c) shows a further embodiment where a grating structure 42.3 and a light detector 4.3 with an aperture 7.3 are arranged on a common substrate 41.3. A guided plane wave 1.3 being launched and propagating towards the grating structure 42.3 is diffracted at the grating structure 42.3 by being scattered at the target molecules arranged at the grating structure 42.3.
[0105] FIG. 7(d) shows a further embodiment where a grating structure 42.4 and a light detector 4.4 with an aperture 7.4 similar to the previous FIGS. 7(a)-(c) are arranged on a common substrate 41.4. A light source generates a free space plane wave 1.4 from below the common substrate 41.4.
[0106] The grating lines (xj, yj) are parabolas and may be described in an orthogonal x-y co-ordinate system by the relation
[00004]
for a plane wave of the incoming coherent light (1.3) with k-vector along the negative y-direction, λ being the wavelength of the coherent light and N the refractive index of the carrier medium. The focal point is at the origin and the y-axis coincides with the symmetry axes of the parabolas.
[0107] For a guided point source (1.1), the grating lines (xj, yj) may be described by the relation
[00005]
[0108] with the grating lines being ellipses with the foci of the ellipses being at the point source and the focal spot of the grating structure, with d being the distance between the point source and the focal point or spot.
[0109] FIG. 8(a) shows a further embodiment of a diffractometric sensing device wherein a plane wave 1.5 is launched along the substrate 41.5 by use of an in-coupling grating 411.5.
[0110] FIG. 8(b) shows a further embodiment of a diffractometric sensing device wherein an integrated laser such as a distributed feedback laser 1.6 is integrated on the substrate 41.6 to launch a plane wave along the substrate 41.6.
[0111] FIG. 8(c) shows a further embodiment of a diffractometric sensing device with a fiber 1.7 with an optical system 11.7 comprising lenses, the fiber 1.7 butt-coupled to the substrate 41.7. The optical system 11.7 is used to launch a plane wave along the substrate 41.7.
[0112] FIG. 9(a) shows a further embodiment of a diffractometric sensing device with a fiber 1.8 butt-coupled to a substrate 41.8 to launch light from a point source into the substrate 41.8.
[0113] FIG. 9(b) shows a further embodiment of a diffractometric sensing device with a point light source 1.9 integrated on the substrate 41.9.
[0114] FIG. 9(c) shows a further embodiment of a diffractometric sensing device with a light scatterer 1.10 arranged on the substrate 41.10.
[0115] FIG. 9(d) shows a further embodiment of a diffractometric sensing device with an integrated in-coupling grating 411.11 for launching light to form a (secondary) point source on the substrate 41.11.
[0116] FIG. 10 show a further embodiment of a diffractometric sensing device having a light source 1.6 integrated on a common substrate 41.12 as the waveguide with the grating structure 42.5 in the carrier medium 45 and an out of plane detector 4.
[0117] FIG. 11(a)-(d) show different embodiments of diffractometric sensing devices with a plurality of grating structures 52.1-52.4 and a plurality of light detectors 4.5-4.8 arranged in an array on a common substrate. FIG. 11(a) shows the example of guided point sources, FIG. 11(b) the example of free space point sources, FIG. 11(c) and FIG. 11(d) examples of guided plane waves.
[0118] FIG. 12a shows a measurement setup with a coherent binding pattern for a total internal reflection (TIR) arrangement. The setup comprises a prism 101 and a substrate 102 which can be separated by an index matching oil. In some embodiments, the prism itself may serve as a substrate. The substrate and prism material is preferentially glass, but any transparent material—i.e. injection moldable polymers—is possible. In addition, it should exhibit low volume scattering, therefore a low photo-elastic coefficient, isothermal compressibility and glass transition temperature of the material is desired (S. Sakaguchi, S.-I. Todoroki, and S. Shibata, “Rayleigh Scattering in Silica Glasses”, J. Am. Ceram. Soc. 79, 2821-2824 (1996)). A focusing grating structure 106 with binding of target molecules thereon, as described throughout the present application, is located on the substrate 102. The grating structure 106 is illuminated under total internal reflection (indicated by the beam P3). The portion of the diffracted light (indicated by P4), is preferentially collected from the prism side by using an objective 103 matching the numerical aperture of the grating structure with the target molecules in combination with a camera or photodiode 104. In some embodiments, a non-transparent spatial filter could be used in conjunction with an array photodetector in place of the objective 103. A reference photodiode or camera 105 is used to reference the totally internally reflected beam, alternatively a beam splitter can be used before the beam enters the prism to reference the incident beam power. In addition, a polarizer in the beam path may be used to control the polarization of the incident beam. The prism areas not used for illumination or collection may be rendered absorptive (i.e. by carbon black paint, chromium black or similar) to reduce stray light. The setup is advantageous, since only the evanescent field is used to sample the target molecules bound to the grating structure which reduces the noise. FIG. 12b shows a possible way to optimize the prism shape to reduce straylight. In this arrangement the diffracted light is collected on the sample side. In principle, the shape of the prism 101 in FIG. 12a can be adjusted similarly to reduce the straylight due to reflected beams. In an embodiment some sidewalls of the prism 101 are designed to minimize reflections, for example, by applying a strongly absorbing coating,
[0119] FIG. 13 shows an embodiment of the objective 203 usable in a TIR configuration 200. The working principle is similar to prior art objectives used in total internal reflection fluorescence microscopy. However, the difference is that the focal plane f1 is not at the same position as the point of total internal reflection, but at a certain distance below the point of total internal reflection at the substrate 202. The focal point or spot f2 of the grating structure 206 with the target molecules is positioned at the height of the focal plane f1, as can be seen in FIG. 13. In some embodiments, deformable lenses are used in order to switch the focus between the focal plane and the substrate. The numerical aperture of the objective 203 for imaging the focal point f2 of the grating structure 206 with the target molecules matches the numerical aperture of the grating structure 206. A drop of immersion oil 29 is arranged between the objective 203 and the substrate 202.
[0120] FIG. 14 shows a setup 300 in the TIR configuration integrated into a standardized wellplate format. An optical prism 301 is connected to an optically clear bottom 307 of an incubation chamber 308 of a standard format wellplate. The prism 301 and the bottom 307 may be monolithic or made of two individual parts fixed to each other. A grating structure 306 with target molecules bound to it is formed on the bottom of the wellplate 307. The diffracted light P4 is collected by an optical system 303 with an aperture matched to the aperture of the grating structure arranged below the standard format wellplate. The optical system 303 either consists of a spatial filter in combination with an arrayed photodetector or an objective. Preferentially, the aperture of the grating structure 306 is smaller than 0.1 to increase the size of the focal spot and hence to increase the mechanical tolerances for an accurate measurement.
[0121] FIG. 15 show an embodiment of the combination of a total internal reflection arrangement and the wellplate format. The grating structure 606 is situated on the transparent bottom 307 of a well 308 in a microtiter plate 603. It is illuminated by a collimated beam (e.g. by collimating lens 602) coming from a fiber 601 at an angle greater than total internal reflection. The light is diffracted into a diffraction limited spot and measured with a detector 4. The illumination of all wells 308 can be performed with one or few laser sources 605 being directed to the fibers for each well 308 by beam splitters or optical switches 604.
[0122] The grating structure can in general be manufactured by different means, such as photolithography or microcontact printing. In an embodiment of the TIR arrangement with microtiter plates, these processes can be conducted on a substrate and bonding to the wells can be performed after creating the structures. Alternatively, the structuring is performed in each individual well.
[0123] FIG. 16 shows four illustrations of the fabrication 526 of the grating structure in the carrier medium by holographic lithography in three dimensions by creating an interference pattern. Then the interference pattern is used to immobilize binding sites in the shape of the interference pattern and thus create a diffraction pattern. Then the diffraction pattern can be read out in specific ways 527. FIG. 16 shows four exemplary specific ways of read-out 527 of the diffraction patterns. The diffracted power can be used to analyze molecular interactions at the binding sites.
[0124] 528 shows how a diverging wave 511 and a converging light path 512 are interfered to create an interference structure 513. When the resulting grating structure 522 is illuminated by the diverging beam 511, the structure causes focusing into a diffraction limited spot or focal point 514.
[0125] 529 shows, how two plane waves 515, 516 are interfered to cause an interference pattern of parallel planes 517. The resulting grating structure 523 causes light to be redirected into a diffracted beam or wave 518 when illuminated by a plane wave 515.
[0126] 530 shows how a diverging wave 511 and a plane wave 515 interfere to cause an interference pattern 519. When the resulting grating structure 524 is illuminated with a plane wave 520 of reverse wavevector k compared to plane wave 515, light is focused into a spot 514.
[0127] 531 shows how a converging wave 512 and a plane wave 515 are interfered. When the resulting grating structure 525 is illuminated with a plane wave 515, light is focused into a spot 514.
[0128] This method can be used in two or three dimensions. Therefore, an integrated fabrication and read-out of the diffractometric sensing device can be achieved. Alternatively, two photon 3D patterning may be used for patterning. A preferable candidate for a suitable matrix material is a hydrogel. Possible alternatives are a mesoporous material or DNA origami.
[0129] FIG. 17 illustrates how the concept of holographic lithography can be implemented in an example of total internal reflection in a wellplate 308. Coherent light is split up by a beam splitter 605 and the wellplate bottom 307 is illuminated by a diverging beam 653 and a plane wave 654 (e.g. collimated by lens 602) through a prism 101. The plane wave 654 is illuminated under an angle that suits the desired readout. Index matching to avoid reflections can be applied. The diverging beam 653 can come in at normal angle of incidence (see left-hand figure referenced as 651) for easier arrangement. Alternatively, not normal illumination can be performed (see central figure referenced as 652). This illumination can be performed such that the signal in the readout scheme is scattered in backward direction. This backward direction can be beneficial in terms of signal to background illumination, because non-coherent background illumination is usually stronger in forward direction. Instead of using fibers 601 free space beam path with lenses for achieving a diverging beam is also an option. It is possible to illuminate entire wellplates 655 with only one light source 605 with the use of optical switches 604 or micro mirrors. The readout of such devices can be performed according to FIG. 15 this corresponds to the scheme 530 illustrated in FIG. 16.
[0130] In the following, a method to probe target molecules using the diffractometric sensing device according to the present invention is described.
[0131] The grating structure can be manufactured by different means, such as e.g. photolithography or microcontact printing. In an embodiment of total internal reflection with microtiter plates, these processes can be conducted on a substrate, and bonding to the wells can be performed after creating the structures. Alternatively, the structuring is performed in each individual well.
[0132] Pulsed source for readout in integrated or fiber based devices:
[0133] By using an ultrafast laser pulse and time resolved measurement of the pulse, the exact location of scatterings can be determined in time domain. This can be used to separate the background light scattered from regions before and after the sensing area. This could also be applied for multiplexing on the same waveguide and assigning the different scatterings to different grating structures with target molecules. The pulse length should be designed to match the grating length.
[0134] Source properties for overall reduction of noise:
[0135] The limiting noise in a coherent sensing technique may arise from interferences of the incident beam with randomly scattered light that is not stable over time. These random interferences cause a temporally changing speckle pattern in the beam envelope of the incident beam, which translates into a temporally changing speckle pattern in the focal plane of the coherent assembly. Any refractive index change within the coherence length of the laser can influence the speckle pattern of the beam envelope of the incident beam. It is therefore desired to limit the coherence length of the laser to the size of the coherent assembly. Other ways to reduce the coherence length is to use a pulsed laser with a pulse duration such that the pulse length matches or slightly exceeds the size of the grating structure. In addition, in order to temporally average the speckle pattern of the incident beam, the laser beam may be shifted laterally with a frequency higher than the acquisition time of the optical sys-tem and an amplitude several times larger than the speckle size but only a fraction of the size of the coherent assembly.
[0136] FIG. 18 shows components of the measurement as used for the method described in the foregoing paragraphs. Graph A shows the spectral width of a laser 401 (intensity as a function of wavelength λ) with a stabilized center wavelength chosen such that the coherence length matches or slightly exceeds the length L of the coherent assembly 406, which is arranged on a substrate 402. λ is the wavelength. Graph B shows the operation of a laser in pulsed mode (intensity as a function of time) with a pulse duration such that the corresponding pulse length matches or slightly exceeds the size of the coherent assembly 406.
[0137] In the lower part of FIG. 18, there is shown a shaking device 409 configured to laterally deflect (indicated by vertical double arrow) the incoming laser beam (indicated by horizontal arrow) by a fraction of the size of the coherent assembly 406 to temporally average the speckles of the incident beam.
[0138] The described method and setup has the advantage that the negative effects arising from a too large coherence length can be reduced by using an appropriate spectral width of the laser and/or an appropriate pulsing of the laser and/or an appropriate deflection of the laser beam.
[0139] In the following, an application of the diffractometric sensing device according to the present invention is described.
[0140] Real time molecular profiling of the human interactome using any coherent binding site arrangement
[0141] The human interactome is the set of protein-protein interactions that occur in human cells. An important advantage of any coherent sensing device is that it enables real-time measurement of binding events in complex samples such as blood and other body fluids, cell cultures or environmental samples. This provides a possibility for classifying such samples based on a large number of binding curves that serve as fingerprints for the specific sample.
[0142] The components and features of a diffractometric sensing device that can perform real time molecular profiling are as follows: [0143] A large diffractometric array of one or more binders (e.g. orthogonally arranged) is exposed to a biological sample (i.e. blood) and generates a continuous binding signal in each element. [0144] The elements of the array can be composed of high-affinity as well as low-affinity binders of any chemical or biochemical form, e.g. peptides, DNA, RNA, lipids, antibodies, polysaccharides or protein fragments. [0145] The individual elements of the diffractometric array can be backfilled with a binder similar or completely different in chemistry to tune the apparent inter-action constant. [0146] The individual elements of the diffractometric array can all be backfilled with the same binder to allow for binding signal normalization. [0147] The signal origin can be determined via a reference array that employs a common backfiller. [0148] Alternatively, or simultaneously, the sample can be spiked with a known con-centration of analyte to calibrate the system and determine the signal origin. [0149] The sample can be diluted by a known substance to a predetermined concentration. [0150] During a binding experiment using a binder array and a biological sample from e.g. a patient the output of the array can be seen as a time-dependent vector, whose trajectory in the high dimensional vector space is unique for the composition of the biological sample. Thus, the array generates a unique finger-print for the biological sample of any patient and condition and is therefore a direct measure of the current health status of the individual. [0151] The obtained trajectory may be compared to a large database of existing binding data linked to genetic, anatomic and clinical data of the corresponding patient by means of machine learning techniques.
[0152] Compared to existing molecular profiling techniques (e.g. HealthTell, Entopsis) a coherent transducer provides real-time information and does not rely on rinsing steps. This allows for the monitoring of weak binders that would otherwise be washed away and the acquisition of molecular kinetic data. For this purpose, different diffractometric binder configurations and arrays may be used, as shown in the following.
[0153] FIG. 19 shows different arrangements of diffractometric binder arrays. FIG. 19(a) shows a rectangular arrangement, FIG. 19(b) shows a staggered arrangement, FIG. 19(c) shows an overlapping arrangement, FIG. 19(d) shows a twisted arrangement, and FIG. 19(e) shows a size-varied arrangement. Thus, multiplexing can be performed in a single compartment by having several grating structures with different binding sites immobilized on the grating structures and by configuring the different grating structures to diffract the light to different locations, which can be achieved by different spatial frequencies (FIG. 19(d)) of the grating and/or by different locations of the gratings (FIGS. 19(a), 19(b), 19(c) and 19(e)).
[0154] FIG. 20 shows a part of a diffractometric binder array consisting of a binder s1 tethered to the surface in the ridge area of the grating pattern s4 with an optional invariable linker s2. The binder array is either uniformly passivated (as indicated by s3) in the grooves of the grating s5 or backfilled with a second binder s6 which is chemically assimilated or not assimilated to the first binder in the grooves of the grating.
[0155] FIG. 21 shows how a diffractometric reference pattern can be employed to determine the binder responsible for the signal in a backfilled diffractometric structure. The referencing scheme consist of the passivated region r1 and the binder r2 as shown in FIG. 21(a) as well as a passivated region r1 combined with the non-binding backfilling molecule r3 as shown in FIG. 21(b). The non-binding backfilling molecule r3 can be either on the grooves or the ridges of the diffractive grating. The final element consists of the combination of the binder r2 and non-binding backfilling molecule r3 in either ridges/grooves or grooves/ridges configuration, as shown in FIG. 21(c).
[0156] FIG. 22 shows monographic experimental data obtained from a pilot study employing a binder denoted by HA that is backfilled with a set of 5 different binders denoted by sHA1 . . . sHA5. The binders are exposed to human plasma and the diffracted signal (square root of light intensity in arbitrary units) is measured as a function of time in minutes. Distinct endpoints and kinetics can be observed for the same sample.
[0157] FIG. 23 shows endpoint data from a diffractometric molecular profiling approach employing 5 different binders denoted HA, HL1 . . . HL4. Human blood serum from 6 different donors denoted D1 . . . D6 is exposed to the binders. The blood serum is incubated and the diffractometric signal is measured at equilibrium.
[0158] FIG. 24 shows comparative endpoint data obtained by traditional immunosignaturing approaches using optical density OD measurement obtained by a fluorescence signals of anti-human Immunglobulin G (IgG) antibodies from the same donors D1 . . . D6 for the same binders denoted HA, HL1 . . . HL4. Comparing FIG. 23 and FIG. 24 reveal drastically different endpoints for the two approaches. This has to do with the fact that the novel diffractometric molecular profiling probes the entire interactome including weak binders, whereas traditional immunosignaturing relies on stringent washing of the assay surface and therefore does not take weak binders into account.
