WO2012156432A1

WO2012156432A1 - Device and probe for detection of infection

Info

Publication number: WO2012156432A1
Application number: PCT/EP2012/059083
Authority: WO
Inventors: Hong Zhang; Maurice Aalders; Tom VAN GOOL
Original assignee: Academisch Medisch Centrum Bij De Universiteit Van Amsterdam; Universiteit Van Amsterdam
Priority date: 2011-05-17
Filing date: 2012-05-16
Publication date: 2012-11-22

Abstract

An activatable device (15) is provided which comprises a device (13) and an activatable imaging probe (1) attached to it. The probe comprises a chromophore (3) and an interaction moiety (5) attached to the chromophore. By interaction of a target (23) with the interaction moiety the optical properties of the probe are altered. An activatable imaging probe for attachment to such activatable device is also provided.

Description

Device and probe for detection of infection TECHNICAL FIELD

The present disclosure relates to the field of methods to detect, prevent and/or reduce colonization of pathogens or microbial contaminations on the surface of a device, and devices for such methods, in particular devices for insertion into a human or animal body, in particular a mammalian body.

BACKGROUND

Several devices are regularly inserted in the human (or animal) body in the course of medical treatments and/or testing, such as various implants, and many of the inserted devices penetrate the skin and have a connection with the outside world of the body, for instance a stoma, a drain in a wound, a deep line in an artery or a vein, a catheter, an insulin tube, etcetera. They need to be changed regularly to prevent them from becoming infected. However, the changing procedure itself poses a risk of (further) infection. At the site where such devices enter the body also a constant danger of infection exists.

Such devices may get colonised by pathogenic microorganisms, especially at their outer ends. As a preventive action, penetrating devices are changed on a regular basis, generally every three or four days. Replacement of such device is a burden to the patient, is costly, and in itself poses a risk of infection.

A goal of the present disclosure is to provide a functionalized device, which is able to in-situ detect and indicate infections, early bacterial, bacilli and/or fungal colonization, microbial contamination and/or other (potential) pathological conditions. Prevention and reduction of

colonization of pathogens on the surface of the device is a further advantage.

Devices for in-situ detection of (pathogenic) targets are known. E.g., WO 2009/074890 discloses methods and devices for continuous in vivo monitoring of a potential infection site. The methods utilize implantable devices for location at an in vivo site. The implantable device is held in conjunction with an optical fiber that detects and transmits an optically detectable signal generated in the presence of a pathogen.

These methods rely on autofluorescence of the target pathogen, possibly in response to an excitation signal. This may result in a relatively poor signal-to-noise ratio and thus make it difficult to assess correctly the amount or concentration of pathogens .

US 2009/0304551 discloses a biconically tapered optical fiber which serves as a biosensor at all optical wavelengths of interest ranging from UV to far IR at subfemtogram per mL sensitivity. The biconically tapered sensor detects biomaterials such as pathogenic species, proteins and DNA and others

biological analytes. Although it uses the principles of

evanescent fields, absorption, adsorption, fluorescence capture and retransmission through the fiber, the detection at the sub- nanogram per mL level is achieved primarily by adsorption or a surface activity due to a refractive index change. The geometry of the biconically tapered optical sensor affects its

performance. The sensing modality is achieved in situ with a source connected at one end of a tapered fiber and a suitable detector at the other end. The tapered region is optionally immobilized with a recognition molecule such as an antibody to the target antigen or a complementary DNA strand. The sample is brought in contact with the tapered region either in batch mode or in a flow mode.

Such device relies on natural fluorescence and therefore exhibits low signal-to-noise ratio. The device can only detect at the location of the tapered portion. Further, optical access to opposite ends of the fiber must be available complicating or even preventing use for detection in vivo.

Y. Zhang et al, "Multi-targeting single fiber-optic biosensor based on evanescent wave and quantum dots", Biosensors & Bioelectronics 26 (2010): 149-154, discloses a fiber-optic evanescent wave biosensor coated with antigens and using

CdSe/ZnS core/shell quantum dots attached to antibodies as labels. Multiplexed immunoassay was demonstrated in a single fiber fiber-optic evanescent wave biosensor constructed with four differently sized quantum dots.

The detection signal is a clearly detectable change in relative intensities of luminescent light with evanescent field coupling to the fiber. However, the method requires attachment of the quantum dots to the targets, which may be unsuitable for use in vivo, in particular for prolonged testing.

Other optical detection probes for indicating certain target cells and/or tissues are also known. E.g. US 2003/00443 discloses activatable imaging probes that include a chromophore attachment moiety and one or more, e.g., a plurality of,

chromophores , such as near-infrared chromophores , chemically linked to the chromophore attachment moiety so that upon

activation of the imaging probe the optical properties of the plurality of chromophores are altered.

Further, US 2009/270269 discloses a sensing system incorporating a nano-scale fluoro-biosensor for detection of specifically targeted bio-contaminants (targets). Select

embodiments use fluorescent nanoparticles such as quantum dots (QD) conjugated to antibody fragments to form a sensor for a specific bio-contaminant based on fluorescent resonance energy transfer (FRET) . A quenching dye may be used to label an analog, while a specific antibody is covalently bonded to a hydrophilic QD . Coupling of QD labeled antibodies and quencher labeled analogs provides enough proximity to produce appreciable FRET- based quenching. Any addition of the target displaces the dye- labeled bacteria, eliminating FRET-based quenching and results in a concentration-dependent increase in QD photoluminescence . Applications include rapid detection and identification, with a high degree of specificity and sensitivity, of a broad range of targets, including viral contaminants, e.g., in less than about three minutes. By using QDs of varying wavelengths the system may be adapted into a multiplexing immuno-assay .

US 2006/147378 discloses an intramolecularly-quenched, near-infrared fluorescence probe that emits substantial

fluorescence only after interaction with a target tissue (i.e., activation) . WO 2009/045579 discloses a nanoparticle-based technology platform for multimodal in vivo imaging and therapy. The nanoparticle-based probes detects diseased cells by MRI, PET or deep tissue Near Infrared (NIR) imaging, and are capable of detecting diseased cells with great sensitivity. The probes also target molecules that localize to normal or diseased cells, and initiates apoptosis of diseased cells.

However, such probes can indicate general information on an analyte or on tissue, but do not provide sufficiently specific data for reliably indicating the early stages of an infection .

SUMMARY

An activatable device is herewith provided, in particular an activatable device for insertion and/or implanting into a human or animal body, in particular a mammalian body, comprising a device and an activatable imaging probe attached to it. The probe comprises a chromophore and an interaction moiety and attached, in particular chemically linked, to the

chromophore. By interaction of a target with the interaction moiety, in particular binding of the target to the interaction moiety or cleaving part of the interaction moiety by the target, the optical properties of the probe, in particular the

chromophore, are altered. Thus, the probe is activated.

A target may comprise microbial cells, bacteria, yeast cells, fungi, multicellular organisms, viruses, tumor cells, antibodies, other pathogens etc.

The probe being attached to the device localises the detection, allows for providing and maintaining a particular probe concentration for extended periods and/or facilitates early and accurate detection of targets binding to the probe and thus detection of colonization and infection of the device.

Further, the chromophores can be removed from the body by removing the device, reducing or preventing remaining probes in the body after treatment or testing.

Thus, an optically activatable, or functionalized, device is provided, which may be used in situ for accurate testing, also for prolonged times and which in some embodiments may be insertable as an alien object into a body of a human or animal and information of the condition of the device may be provided that may prevent premature or overdue removal and/or exchange of the device.

The altered optical properties of the chromophores may comprise (de- ) quenching, and/or changes in wavelength, in fluorescence or phosphorescent lifetime, in spectral properties and/or in polarisation of emitted or reflected light.

E.g., the probe may comprise a quenching moiety attached, in particular chemically linked, to the chromophore, having a quenching effect on the chromophore which is configured to be altered, in particular reduced or cancelled by interaction of the target with the interaction moiety. E.g., by interaction of the target with the interaction moiety the quenching moiety may be chemically altered, physically altered e.g. by reforming part of the probe such as deformation and/or repositioning part of a protein with respect to the chromophore. Also, the

quenching moiety may be at least partly detached from the probe. Thus, the probe is dequenched and the chromophore can emit light so that an optical signal can be provided, indicative of

interaction with the target.

The quenching moiety may be attached to, in particular chemically linked to, the interaction moiety, and it may be part of the interaction moiety. Also, by the interaction of the target with the interaction moiety at least a portion of the quenching moiety may be separated from the probe. In particular in an activatable device that is insertable into a human or animal, the separated portion may preferably be biodegradable, e.g. by destruction by leucocytes, by destruction or excretion through the renal tract, the digestive tract or by some other natural process of the body. Thus, the probe may be irreversibly dequenched and, where applicable, the body may not be harmed.

The device may comprise plural probes, comprising different interaction moieties for interaction with different targets and providing different alterations in the optical properties of their respective chromophores. Also, or alternatively, the probe may comprise plural different interaction moieties for interaction with different corresponding targets and/or may comprise different quenching moieties, and the probe may be arranged to provide different alterations in the optical properties of the chromophore upon interaction of a particular target with an interaction moiety.

Thus, different targets may be reliably identified, e.g. different interaction moieties may be specific for

particular (strains of) bacteria. Upon detection of infection by such (strain of) bacteria, specific antibiotic medicaments may be used for treatment, instead of commonly employed broad-range antibiotics, and development of resistance against the broad- range antibiotics may be reduced or prevented. Different

quenching moieties may be affected by different targets

interacting with an interacting moiety. Thus, one probe can signal interaction with a particular target due to dequenching of a particular emission and/or absorption wavelength of the chromophore quenched by the respective quenching moiety.

Suitable interaction moieties may comprise, e.g. to signal different pathogens and/or their products, an antibody, an antigen, a receptor, or an aptamer, or at least a functional part thereof. A functional part here meaning a part sufficient for interacting with the target like binding to or cleavage by the target. In an aptamer, which is a DNA fragment with double strand and single strand parts, single strands may provide binding capacity for binding to the chromophore, for binding the quenching moiety, and for binding of a target to the probe attached to the aptamer. In the latter case the aptamer serves also as an attachment moiety. Aptamers may be custom designed to serve particular desires, e.g. see C. Tuerk, L. Gold,

"Systematic evolution of ligands by exponential enrichment: RNA ligands to bacteriophase T4 DNA polymerase" Science 249 (1990) : 505-510, or (2) A.D. Ellington, J.W. Szostak, "In vitro

selection of RNA molecules that bind specific ligands", Nature 346 (1990) : 818-822.

The probe may comprise a chromophore arranged for emitting phototherapeutic light, e.g. light of a wavelength which is noxious for a pathogen or rather curative or beneficial to a particular process. This allows disinfection of the device in situ. This chromophore may be the same chromophore for detection or may be a further chromophore, possibly of a

different nature. Absorption and/or emission of such further chromophore may be quenched by a quenching moiety, which may be identical or a different quenching moiety, affected by the target interacting with the interaction moiety. The probe may also comprise a photosensitizer moiety which may be activated by the emission of a chromophore of the activated probe, e.g. for in situ therapy.

In the probe, a chromophore may comprise an inorganic chromophore, which may have increased resistance to

biodegradation inside a human or animal body compared to organic chromophores .

In the probe, a chromophore may comprise a

nanoparticle, e.g. a quantum dot. An inorganic nanoparticle, e.g. a nanocrystal, is preferred. An inorganic chromophore may comprise a rare-earth nanoparticle, e.g. a probe may comprise a lanthanide-based optical imaging probe, which may comprise a crystal comprising one or more lanthanide ions as an emitter. Suitable lanthanides may comprise Europium, Samarium, Terbium, in particular Erbium and/or Ytterbium. A nanoparticle may comprise a plurality of portions with different compositions, e.g. a core/shell or multishell-ob ect wherein one portion is surrounded by a shell comprising a different composition E.g., an inorganic nanoparticle comprising alternating shells with different amounts of doping. CdSe/ZnS core/shell quantum dots may be provided, which exhibit a high resistance to

photodegradation and size-dependent, tunable and high-yield photoluminescence .

A chromophore may be arranged to absorb light at a first wavelength and to emit light at a second wavelength, different from the first wavelength, once activated. This way, the second, emission, wavelength may be separated from the first, excitation, wavelength, improving the signal-to-noise ratio. The chromophore may exhibit fluorescence and/or phosphorescence .

The emitted second wavelength may be shorter than the absorbed first wavelength. This further improves signal-to-noise ratio since luminescence of biological material will generally have a wavelength longer than the first wavelength.

A shorter second wavelength may be achieved by 2-photon absorption and frequency doubling, or other similar techniques, but preferred is frequency upconversion via electron shelving or other similar relatively slow techniques that do not rely on (near-) simultaneous multiphoton absorption, since these

generally require less intensity for excitation and thus may assist sparing surrounding tissues of the body.

The chromophore may be arranged for absorbing light with a near-infrared wavelength in a wavelength range of about

800-2100 nm, preferably in a range of about 800-1500 nm, e.g. in a range of about 900-1200 nm such as about 1000 nm, and emitting (near- ) visible light in a wavelength range of about 400-800 nm, preferably in a range of about 500-700 nm, e.g. about 550 nm and/or 650 nm. The near-infrared (NIR) wavelength for absorption and excitation has a relatively large penetration depth in mammalian tissue and induces little to no (auto-) luminescence of the tissue, improving the signal-to-noise ratio. It further allows transdermal excitation of an intradermal or subdermal probe by a NIR-light source outside the body. A (near-) visible wavelength in the range 400-800 nm facilitates detection due to a large number of available optical conductors (e.g. optical fibers) and/or detectors for such wavelengths. Further, light with a wavelength of about 600-700, e.g. about 650 nm also has a relatively large penetration depth in mammalian tissue and such light emitted by an intradermal or subdermal probe may be detectable outside the body. An emission wavelength of about 550 nm or less may be noxious, preferably inactivating or lethal, for a pathogen.

Any device to be inserted for longer or shorter time into an analyte and/or into the body may be provided as a claimed device, including surgical tools such as endoscopes, forceps, suction devices and/or suturing materials such as needles, clamps and/or staples. In particular, the device may comprise an implant, e.g. a pacemaker, a joint implant such as an artificial hip or knee joint portion, a breast implant, etc. Also, or alternatively, the device may comprise a portion for penetrating skin of the body, in particular mammalian skin, and it may be arranged partly within and partly outside the body, e.g. a catheter, an infusion drip line, a bone support, a stoma, a Kirchner wire, etc, which are particularly prone to infection and generally are removed and/or replaced according to

established protocols.

The device may comprise a translucent body and/or a light guide, e.g. a translucent wall portion and/or an optical fiber to facilitate providing excitation light to the probe and/or capture and detect of emitted luminescence. In

particular, a device comprising a translucent body and/or a light guide protruding from the body facilitates optical access to the probe.

The device need not be fully coated with the probe, but for localised detection may comprise one or more separate surface portions coated with a material comprising the

activatable imaging probe and/or surface portions coated with materials comprising the activatable imaging probe in different concentrations, and/or, in case of a device of claim 3 or claim 4, surface portions coated with different probes.

The device may be designed for testing other analytes in laboratoria, in industrial processes or in the field, e.g. an optical fiber probe for testing swimming pools or drinking water for bacteria like E. coli, V. cholerae etc. The latter may be particularly helpful to prevent (spreading) disease in disaster areas. To increase detection surface a probe may comprise plural light guides which merge to a single light guide, e.g. a fibre bundle. A testing kit may comprise one or more activatable devices and a detector for detecting activation of the probe and/or a light source providing a wavelength for exciting a chromophore. The device and the detector and/or light source may comprise mated connectors. The light source and the detector may be integrated in a single apparatus. At least the device and/or the entire kit may be sterilizable and/or be packed sterile. An activatable and/or a device comprising activated probe may be disposable .

The activatable device may be provided by attaching an activatable probe to the device, e.g. via coating techniques, such as by coating the device with a coating composition

comprising a suitable probe concentration, e.g., a dispersion of the probe in a suitable solvent. To facilitate attachment of the probe to a device, the probe may be provided with an attachment moiety .

For (use in a method of) providing an activated device as herein described, an activatable imaging probe is herewith provided. The activatable imaging probe comprises a chromophore and an interaction moiety attached, in particular chemically linked, to the chromophore so that upon activation of the imaging probe, the optical properties of the chromophore are altered, wherein the probe is activated by interaction of a target with the interaction moiety, in particular binding of the target to the interaction moiety or cleaving part of the

interaction moiety by the target. The probe further comprises an attachment moiety for attaching the probe to a device, in particular to a device for insertion and/or implanting into a human or animal body. In line with the above, the device and/or the probe may be used for detecting interaction with the probe by a target and in particular binding to and/or colonisation of the device by a target. The device may be inserted in an analyte or in a subjects' body and interaction and/or colonisation may be monitored by monitoring optical alterations of the probe in situ. E.g., a device such as an optical fiber may be placed in a blood vessel for an extended period during which period the fiber may "capture" targets out of the blood flowing past it. Analysis of the activatable imaging probe may take place at certain intervals, or may take place continuously during this period. This allows sampling of significantly larger volumes of blood than the customary single or a few test tubes, which may significantly reduce the detection limit for certain targets and/or conditions. In addition, the device may be removed from the body after some time and detection and/or immunoassays may be carried out in vitro, facilitating analysis of the device in a controlled environment. Similarly, other body portions like lymph vessels, the ventral cavity etc. may be probed for

extended time.

The device and/or the probe may also be used for treatment, in particular photodynamic therapy with or without use of a photosensitizer . It is noted that in this text, "probe may refer to a single particle or to a quantity of plural probe particles, as will be apparent from the context.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-described aspects will hereafter be more explained with further details and benefits with reference to the drawings showing an embodiment of the invention by way of example .

Fig. 1 indicates an activatable imaging probe;

Fig. 2 indicates an activatable device comprising the activatable imaging probe of Fig. 1 attached to it;

Fig. 3 indicates the activatable device of Fig. 2 partly inserted into a mammalian body, excited by radiation but emission being quenched so that no signal is detected;

Fig. 4 indicates the activatable device of Fig. 2 partly inserted into a mammalian body, having been activated by binding of a target to the attached probe and detachment of a quenching moiety, the probe being excited by radiation through the device and emitting fluorescence into the device and being detected by a detector;

Fig. 5 indicates another activatable device implanted into a mammalian body, having been activated by binding of a target to the attached probe, the probe being excited by

radiation through the skin and emitting fluorescence through the skin being detected by a detector;

Figs. 6-10 are similar to Figs. 1-5, respectively, however indicating an activatable imaging probe and an activatable device comprising the probe, respectively, wherein the probe comprises a quenching moiety;

Fig. 11 indicates an inorganic chromophore;

Fig. 12 indicates photon upconversion transitions;

Fig. 13 indicates an upconversion spectrum of the chromophore of Fig. 11;

Fig. 14 indicates a downconverssion spectrum of the chromophore of Fig. 11.

DETAILED DESCRIPTION OF EMBODIMENTS

It is noted that the drawings are schematic, not necessarily to scale and that details that are not required for understanding the present invention may have been omitted. The terms "upward", "downward", "below", "above", and the like relate to the embodiments as oriented in the drawings, unless otherwise specified. Further, elements that are at least

substantially identical or that perform an at least

substantially identical function are denoted by the same

numeral, where useful individualised with an alphabetic suffix.

Figs. 1-5 show an activatable imaging probe 1 comprising a chromophore 3 to which an interaction moiety 5 and an attachment moiety 7 are attached. Figs. 6-10 show an

activatable imaging probe 1A similar to that of Fig. 1 but further comprising a quenching moiety 9. Also shown are

biocompatibility moieties 11 such as polyethylene glycol (PEG) attached to the chromophore 3. The probe 1 is further capped. Thus, except for the attachment moiety 7, the probe 1 is not bioactive. The interaction moiety 5 may comprise an antibody for selective binding to a particular target, e.g. a microbial cell or a cancer cell. E.g., specific antibodies exist for several major hospital infections.

The surface of rare-earth doped upconversion nanoparticles may be rendered biocompatible and be activated using a Si0₂ shell and an amphiphilic polymer in order to promote the association of the nanoparticle with sensitizer molecules and biomolecules/DNA.

Functionalization of the nanoparticles may be achieved by controlled polymerization of an alkoxysilane at the surface of the nanoparticles following two approaches: (i) directly polymerizing a silane at the surface of the particles that will be functionalized with a

guanidinium group and (ii) polymerizing a silane bearing a terminal epoxy group that is then opened by reacting with guanidine.

Fig. 2 further indicates a light guide 13, e.g. an optical fiber 13, or a translucent wall of a catheter as an example of a device for insertion and/or implanting into a mammalian body. A suitable fiber may comprise a silicon core and/or a silica cladding layer and may be stripped to bare a silica outer surface layer, but an activatable device as

presented herein may also be coated and/or otherwise provided with an outer surface that is biocompatible. The probe 1 is chemically attached to the fiber 13 providing an activatable device 15.

Attaching the probe 1 to the fiber 13 may e.g. be performed as described in A.K. Singh, et al . , "Development of sensors for direct detection of organophosphates . Part I:

immobilization, characterization and stabilization

ofacetylcholinesterase and organophosphate hydrolase on silica supports" Biosensors & Bioelectronics 14 (1999) 703-713.

A covalent binding between the probe 1 and the fiber 13 is in principle very stable and substantially prevents

detachment of the probe 1.

The fiber 13 may be monomode, multimode, step-index but preferably comprises a graded index fiber, to increase

efficiency for transmitting plural wavelengths and/or coupling light into and out of the fiber 13.

Fig. 3 indicates the activatable optical fiber 15 of Fig. 2 having a distal portion penetrating the skin 17 of a mammal, e.g. being inserted into a human organ. A proximal portion of the fiber 15 protrudes from the skin 17. A light source 19 is optically coupled to the fiber 13 so that light of a suitable wavelength for exciting the chromophore 3 may be inserted into the fiber 13 (see the white arrows) . The

excitation light can then be transmitted through the fiber 13 and couple to (the chromophore 3 of) the probe 1. The light source may emit white light, which may be filtered, or one or more spectral bands or lines, e.g. originating from one or more light emitting diodes and/or lasers.

Any luminescence from the probe 1 (dotted wavy arrows) may be detected by a detector 21 optically coupled with the fiber 13 to provide a signal. In the case of Fig. 3, the

resultant signal may be used as a reference signal, since (the interaction moiety 5 of) the probe 1 has not (yet) interacted with a target. For (spectral) analysis of detected optical signals, any (automated) detection may be used.

Fig. 4 indicates the same set-up as Fig. 3. However, here a microbial cell 23 is bound as a suitable target 23 to the interaction moiety 5. Because of this binding the energy levels and thus the optical properties of the probe 1, in particular the chromophore 3, are altered. Such alteration may be detected by the detector 21 as a change in signal strength, but

preferably, the probe 1 is configured to provide a spectral change, i.e. emission of another wavelength upon activation.

Since the probe 1 is attached to the fiber 13, the chromophore 3 will remain in a substantially constant close contact with the surface of the fiber, and thus there will be close coupling with an evanescent field of a light wave in the fiber. Thus, the probe may be efficiently excited by light from the fiber 13, and luminescence light emitted by the chromophore 3 on a distal end of the fiber 13 will be readily detected by the detector 21 at the proximal end of the fiber 13. Such high coupling efficiency may also be employed with other devices, enabling optical detection with devices and/or analytes

previously unsuitable, e.g. due to relatively low

transmissibility for the used wavelengths.

Fig. 5 indicates an activatable device 15B comprising the probe 1 of Fig. 1. Here, the device 15B is completely implanted under the skin 17 into a mammalian body. As in Fig. 4, the probe 1 has been activated by binding of a target 23. Here, however, the probe 1 is excited by NIR radiation through the skin 17 from a light source 19. Light emitted by the activated excited probe 1 is detected outside the skin 17 by the detector 21.

As another option indicated in Fig. 5, a separate imaging fiber 25 or other light guide may be inserted into the body close to the device 15B for providing excitation light and/or capturing and detecting emitted light from the activated device 15B with a detector 27. Thus, a condition of an

activatable implant 13B may be tested with an endoscope via an artificial or natural orifice of the body, such as a checking a pacemaker via a port-a-cath, a stomach reduction band via esophagal/stomach endoscopy, and/or a cardial by-pass via a gastroscope. It is further possible to use a fluid column, e.g. a translucent or clear infusion fluid, through an otherwise opaque conduit as the light guide.

Upon detection of a predetermined signal (strength), the device 15 may be removed from the body, or a suitable therapy may be started. A therapy may comprise optical therapy, e.g. UV irradiation through the fiber 13 for disinfecting it.

Figs. 6-10 are substantially similar to Figs. 1-5, showing an activatable probe 1A comprising a quenching moiety 9 and (Figs. 7-10) an activatable device 15A comprising such activatable probe 1A. Without interaction of a target 23 with the interaction moiety 5, the quenching moiety 9 interferes with the energy spectrum of the chromophore 3 and reduces or prevents absorption of the excitation light and/or emission of

luminescence light by (the chromophore 3) of the probe 1A. A detector 21 optically coupled with the fiber 13 therefore will not detect a luminescence signal (in Fig. 8) .

However, when a target 23, e.g. a microbial cell 23 is bound as a suitable target 17 to the interaction moiety 5, the energy levels of the probe 1 are altered and a portion 9' of the quenching moiety 9 of the probe 1A may be detached from (the chromophore 3 of) the probe 1A. Thus, the probe 1A, and

therewith the device 15A, have become activated and may emit detectable light, after excitation by light transmitted through the device 13 (Fig. 9) or where applicable by light transmitted through the skin 17 of the subjects body (Fig. 10) . As an example of a suitable chromophore 3, Fig. 11 shows an inorganic core-shell nanoparticle . The core 29

comprises a NaYF₄ nanocrystal doped with Erbium and Ytterbium forming Er³⁺ and Yb³⁺ ions in the nanocrystal. The shell 31 comprises silica and may comprise polyethyleneimine (PEI) to promote attachment of functional groups to the nanocrystal to form an activatable probe.

An Yb/Er-doped NaYF₄ nanocrystal chromophore suitable for the present activatable probe may be provided along the lines of Q.Chen, et al, "Functionalization of upconverted

luminescent NaYF₄:Yb/Er nanocrystals by folic acid-chitosan conjugates for targeted lung cancer cell imaging", J. Mater.

Chem. (2011), (Advance article online DOI : 10.1039/COJM04468G) .

As indicated in Fig. 12, upon irradiation the nanoparticle with light having a wavelength of about 980 nm, the Yb- and Er-ions in such nanoparticle may be excited to different levels. The excitation energy is redistributed to Er-ion levels which show radiative decay with weak emission in green

wavelengths around 520 nm and 540 nm ("G" in Fig. 12) and strong red emission in wavelengths around 650 nm ("R" in Fig. 12), cf .

Fig. 13, showing intensity in arbitrary units versus wavelength λ in nanometer. Excitation may also be performed with a wavelength of about 810 nm. Further, downconversion processes result in radiative emission around 1520 nm, cf . Fig. 14, showing

intensity in arbitrary units versus wavelength λ in nanometer, which has a long penetration depth through mammalian, in

particular human, tissue.

Relatively short emission wavelengths of around 520 nm and 540 nm and/or shorter may be particularly useful for

exciting a photosensitizer , e.g. Rose Bengal, while longer wavelengths may be used with mTHPC (650 nm) or photofrin (630 nm) . Various suitable photosensitizers are e.g. listed on the website http : / /www . photobiology .info/Berg. html .

Emission wavelengths of around 650 nm are particularly useful for imaging. Emission wavelengths of around 1520 nm are particularly useful for diagnosis. (Chromophores with) particular wavelengths may be selected for use with different analytes.

Emission of a chromophore, in particular a

nanoparticle, may be tunable by selection of the excitation wavelength. The emitted light can be used for selective

detection of cell type, e.g. tumor cell or HIV cell, and/or selective determination of microbial infection, e.g. bacteria or virus, possibly allowing detection of the specific kind or strain. While some wavelengths will be useful in detection, other wavelengths can e.g. be used to excite a photosensitizer for photodynamic therapy. The relative intensity of the emission wavelengths may depend on the excitation wavelength. Therefore, using the right combination of illumination wavelengths in succession may give a switchable system: detection followed by destruction.

Thus, a functionalized device is provided which is able to in-situ detect and indicate early bacterial and fungal colonization. In an embodiment of a device, a catheter can perform photodynamic therapy for the destruction of the targets to avoid the stage where the patient will start to suffer from catheter related complications. In an embodiment, the

functionalization of the device utilizes (i) luminescence up- conversion nanocrystals (multicolour visible emission under near-IR excitation) whose emission of light is quenched until bound to a specific strain or type of microorganism; and (ii) photosensitizing molecules for photodynamic therapy (PDT) .

Thus, immobilizing targeting and therapy functions may be integrated with upconversion nanocon ugates at the surface of a device, in particular an optical fibre. The picked-up targets can then be subject to photodynamic therapy at the surface of the fibre. By using different nanoparticles with different emission wavelengths for the different strains detection of colonisation is enabled which may comprise determination of the responsible strain.

Particular advantages of the presented approach

comprise (i) The detection may be in vivo and the catheter can remain in the blood vessel until the amount of colonization reaches a critical threshold, (ii) The NIR light excitation and visible light detection configuration can significantly increase the detection sensitivity by minimizing the autofluorescence of the surrounding material, (iii) Destruction of specific targets based on PDT can be carried out after their detection.

Besides a functionalized catheter, this approach has many other potential applications in the biomedical field for which this technique can be valuable, e.g. the detection of minimal amounts of circulating cancer cells and/or the specific detection of different strains of bacteria in the blood stream.

The present activatable devices, probes and their uses conform to the demand for increasing speed of recovery of patients, reducing the residence time in hospitals and reducing costs .

One or more surface portions of the device may be coated with a material comprising the activatable imaging probe, e.g. providing regions and/or bands on the device for particular monitoring of such portion. In an embodiment, different portions may be coated with different probes and/or with different densities of probe entities, further facilitating determination of targets.

The invention is not restricted to the above-described embodiments, which can be varied in a number of ways within the scope of the claims. For instance, visible luminescence light may be visually inspected, instead of with a detector.

Elements and aspects discussed for or in relation with a particular embodiment may be suitably combined with elements and aspects of other embodiments, unless explicitly stated otherwise .

Claims

1. Activatable device (15, 15A, 15B) , in particular for insertion and/or implanting into a human or animal body, comprising a device (13, 13B) and an activatable imaging probe (1, 1A) attached to it, the probe comprising a chromophore (3) and an interaction moiety (5) attached, in particular chemically linked, to the chromophore, wherein by interaction of a target (23) with the interaction moiety the optical properties of the probe are altered.

2. Activatable device (15A) of claim 1, wherein the probe (1A) comprises a quenching moiety (9) attached, in

particular chemically linked, to the chromophore (3), wherein the quenching moiety has a quenching effect on the chromophore which is configured to be altered by interaction of the target (23) with the interaction moiety (5) .

3. Activatable device (15, 15A, 15B) of any preceding claim, wherein the device comprises plural probes (1, 1A) , comprising different interaction moieties (5) for interaction with different targets (23) and providing different alterations in the optical properties of their respective chromophores (3) .

4. Activatable device (15, 15A, 15B) of any preceding claim, wherein the probe comprises plural different interaction moieties (5) for interaction with different corresponding targets (23) and/or, in the case of a device of claim 2, comprises different quenching moieties (9), and wherein the probe is arranged to provide different alterations in the optical properties of the chromophore (3) upon interaction of a particular target with an interaction moiety.

5. Activatable device (15, 15A, 15B) of any preceding claim, wherein the interaction moiety (5) comprises at least a functional part of a receptor, an antibody, an antigen or an aptamer.

6. Activatable device (15, 15A, 15B) of any preceding claim, wherein the probe (1, 1A) comprises a chromophore (3) arranged for emitting phototherapeutic light and/or comprises a photosensitizer moiety.

7. Activatable device (15, 15A, 15B) of any preceding claim, wherein a chromophore (3) comprises an inorganic

chromophore and/or a nanoparticle .

8. Activatable device (15, 15A, 15B) of any preceding claim, wherein a chromophore (3) is arranged for absorbing light at a first wavelength and emitting light at a second wavelength different from, preferably shorter than, the first wavelength.

9. Activatable device (15B) of any preceding claim, wherein the device comprises an implant.

10. Activatable device (15, 15A) of any preceding claim, wherein the device comprises a portion for penetrating skin of the body.

11. Activatable device (15, 15A, 15B) of any preceding claim, wherein the device comprises a translucent body and/or a light guide.

12. Activatable device (15, 15A, 15B) of any preceding claim, comprising one or more separate surface portions coated with a material comprising the activatable imaging probe (1, 1A) and/or surface portions coated with materials comprising the activatable imaging probe in different concentrations, and/or, in case of a device of claim 3 or claim 4, surface portions coated with different probes.

13. Activatable imaging probe (1, 1A) ) for manufacture of a device (15, 15A, 15B) of any one of claims 1-12, the probe comprising a chromophore (3) and an interaction moiety (5) attached, in particular chemically linked, to the chromophore so that upon activation of the imaging probe, the optical

properties of the chromophore are altered, wherein the probe is activated by interaction of a target (23) with the interaction moiety, wherein the probe comprises an attachment moiety (7) for attaching the probe to a device (13, 13B) for insertion and/or implanting into a human or animal body.

14. Method of manufacturing an activatable device (15, 15A, 15B) of any one of claims 1-13, comprising attaching an activatable imaging probe (1, 1A) to a device (13, 13B) , wherein the probe comprises a chromophore (3) and an interaction moiety (5) attached, in particular chemically linked, to the

chromophore so that upon activation of the imaging probe, the optical properties of the chromophore are altered, wherein the probe is activated by interaction of a target (23) with the interaction moiety.

15. Use of an activatable device (15, 15A, 15B) of any one of claims 1-12 or of an activatable imaging probe (1, 1A) of claim 13 for detecting interaction with the probe and a target (23) and in particular binding to and/or colonisation of the device by a target.