The present invention relates to a probe-type SQUID system. More particularly, the present invention relates to using the probe-type SQUID system to detect magnetic particles stored in living organism or magnetic-labeling indicators for immunoassays and tumor or other application.
Magnetic nanoparticles within bodies are the metal and metallic oxide particles with bio-function coating, which are manufactured from either a physiology reaction in living beings or an artificial synthesis. The natural organic ones within bodies include copper group, like ceruplasmin and hCtr human copper transport protein, iron type, such as transferrin and hemosiderin, etc. Because they are the indicators related to Wilson disease, diseases of iron deficiency anemia, and hemochromatosis, their amount are usually examined by blood tests, invasive biopsy examines, and some noninvasive methods, such as magnetic resonance image (MRI) and SQUID-Biosusceptometry. Between them, blood tests are the cheapest but low sensed and specific; invasive biopsy examines are dangerous especially for the old, pregnant, etc. even though it owns the advantages of high sensitivity and specificity. Similarly, although MRI and SQUID-biosusceptometry with the high sensitivity and specificity are noninvasive, the drawbacks of high-cost/maintenance and complicate operating are difficult for wide publication. Further, the SQUID-biosusceptometry using SQUID to detect the signal directly, which has the drawbacks that has big interference and noise, and the detecting signal would be low.
For artificial synthesis, those are usually specific for the biomagnetism applications, classified into two kinds, i.e. the type of dynamics controlling, like cell separation, tumor treatment, drug deliver, and the type of detection, such as tumor diagnosis, immunoassay, etc. The last kind, in other words, is that these particles as a magnetic labeling are bound to the target proteins or molecules, and then results in the variation of the specific magnetic susceptibility for the determination of the position or the amount of target ones.
In the detection of magnetic nanoparticles, the requirement of high sensitivity is important because it relates to the successful possibility of curing disease in the early stage disease. For example, in tumor diagnosis, the tumor size of 1 mm generally indicates that the tumor cells are as more as one millions. In this stage of the tumor growth, the tumor transferring to other locations in the torso are usually happened. So the tumor even is found and then removed away by the surge, but sometimes another tumor in other positions of the torso grows up in few days later. The commercial ultrasonography and MRI (magnetic resonance image) technology are limited to the spatial resolutions around several millimeters. However, by SQUID detector detecting the tumor labeled with magnetic nanoparticles, the sensitivity could be improved to micrometer scale. There have been some inventions about the SQUID which connects with a probe to detect magnetic materials. For example, U.S. Pat. No. 5,293,119 discloses an electromagnetic microscope for evaluation of electrically conductive and magnetic materials, which combines SQUID with a probe for use in nondestructive evaluation to evaluate many metal high-technology products or in public infrastructure. However, there has no invention or concept about the probe type SQUID for detecting magnetic particles within living beings.
The present invention relates to a probe-type superconducting quantum interference device (SQUID) system for detecting magnetic particles within a living oragnism, comprising: (a) a probe union, which has a double D-shape pickup coil inserted in the center of a excitation coil, for closing to the living organism, wherein the probe union is coupled with a cooling module such as TE cooler module to avoid power heating, (b) a SQUID union comprising a SQUID surrounded by a input coil is inserted in a Dewar and within a shielding can, and (c) a connecting electrically conducting wire sych as copper wire for transferring the signal from the pickup coil of the probe to the input coil.
The present invention further relates to a non-invasive method for detecting magnetic particles within a living organism by a probe-type SQUID comprising (a) a probe union, which has a double D-shape pickup coil inserted in the center of a excitation coil, for approaching to a sample, wherein the probe union is coupled with a cooling module such as TE cooler module to avoid power heating, (b) a SQUID union comprising a SQUID surrounded by a input coil is inserted in a Dewar and within a shielding can, and (c) a connecting electrically conducting wire such as copper wire for transferring the signal from the pickup coil of the probe to the input coil, the method comprises (1) approaching the living organism with the probe to magnetize and sense signal from the living organism, (2) the connecting electrically conducting wires transfer the signal from the pickup coils of the probe to the input coil surrounding SQUID sensor, and (3) generating magnetic signal intensity to evaluate the magnetic particles in the living organism.
In the present invention, the framework of the probe-type SQUID system is utilized to magnetize and sense the sample efficiently by the probe composed of the pickup coil and excitation coil for closing to the sample. Then the connecting electrically conducting wires such as copper wires transfer the signal from the pickup coil of the probe to the input coil surrounding SQUID sensor. It is noticed that the signal transferring means the level of magnetic signal intensity could be amplified from the pickup coil to the input coil by adequate designs of those, rather than only the signal propagation.
The present invention relates to a probe-type superconducting quantum interference device (SQUID) system for detecting magnetic particles within a living organism, comprising: (a) a probe union, which has a double D-shape pickup coil inserted in the center of a excitation coil, for closing to the living organism, wherein the probe union is coupled with a cooling module such as TE cooler module to avoid power heating, (b) a SQUID union comprising a SQUID surrounded by a input coil is inserted in a Dewar and within a shielding can, and (c) a connecting electrically conducting wire such as copper wire for transferring the signal from the pickup coil of the probe to the input coil.
The term “SQUID” used herein refers to superconducting quantum interference device (SQUID), is a sensitive detector which is used to measure extremely weak signals, such as subtle changes in the human body's electromagnetic energy field based on the quantum mechanical Josephon effect. A Josephson junction is made up of two superconductors, separated by an insulating layer so thin that electrons can tunnel through. A SQUID consists of tiny loops of superconductors employing Josephson junctions to achieve superposition: each electron moves simultaneously in both directions. Because the current is moving in two opposite directions, the electrons have the ability to perform as qubits (that theoretically could be used to enable quantum computing).
The term “TE cooler module” used herein refers to use the Peltier effect to create a heat flux between the junction of two different types of materials. A Peltier cooler, heater, or thermoelectric heat pump is a solid-state active heat pump which transfers heat from one side of the device to the other side against the temperature gradient (from cold to hot), with consumption of electrical energy. Such an instrument is also called a Peltier device, Peltier diode, cooling diode, Peltier heat pump, solid state refrigerator, or thermoelectric cooler (TEC). Because heating can be achieved more easily and economically by many other methods, Peltier devices are mostly used for cooling. However, when a single device is to be used for both heating and cooling, a Peltier device may be desirable. Simply connecting it to a DC voltage will cause one side to cool, while the other side warms. The effectiveness of the pump at moving the heat away from the cold side is totally dependent upon the amount of current provided and how well the heat from the hot side can be removed.
In SQUID union, an rf high-Tc SQUID surrounded by the input coil was inserted in the deware filled with liquid nitrogen and within the electromagnetically shielding can (MAS-C105, MagQu Co. Ltd.). The shielding can is composed of five sub-cylindrical cans by different materials and structures, and results in the satisfying shielding factor from 80˜100 dB ranged from DC to 1 kHz.
Based on the design of double D-shape pick-up coils, the surrounding noise and excitation field could be suppressed effectively. The connecting wire between the pickup coil of the probe and the input coil of the SQUID union is twisted and shielded by some shielding materials for anti-coupling the surrounding noise. Besides, some electronics like the power supply for excitation filed, etc. are also shielded by adequate metal plates. The most important of all, not only the intrinsic thermal noise of metallic pickup coil is controlled by the optimum design, but also that influenced by the heat from the excitation coil of 60 W is suppressed by the cooling mechanism, as shown in the
The present invention further relates to a noninvasive method for detecting magnetic particles within a living organism by a probe-type SQUID comprising (a) a probe union, which has a double D-shape pickup coil inserted in the center of a excitation coil, for apprpaching to a sample, wherein the probe union is coupled with a cooling module such as TE cooler module to avoid power heating, (b) a SQUID union comprising a SQUID surrounded by a input coil is inserted in a Dewar and within a shielding can, and (c) a connecting electrically conducting wire such as copper wire for transferring the signal from the pickup coil of the probe to the input coil, the method comprises (1) approaching the living organism with the probe to magnetize and sense signal from the living organism, (2) the connecting electrically conducting wires such as copper wires transfer the signal from the pickup coils of the probe to the input coil surrounding SQUID sensor, and (3) generating magnetic signal intensity to evaluate the magnetic particles in the living organism.
The method can be applied to detect magnetic particles within a living organism, which are indicators related to Wilson disease, diseases of iron deficiency anemia, or hemochromatosis without biopsy or MRI method. Also, the other applications like detecting magnetic labeling bound to target proteins, moleculars, tumor treatment, drug deliver, tumor diagnosis or immunoassays, can all use the method of the present invention to detect the magnetic particles with high sensitivity. The magnetic labeling can be ferri- or ferromagnetic particles themselves may be of any material which, although preferably non-radioactive (unless the particles are also intended to be detected by their radioactive decay emissions), exhibits ferri- or ferromagnetism in domain and sub-domain sized crystals. Conveniently the particles will be of a magnetic metal or alloy, e.g. of pure iron, but more preferably they will be of a magnetic iron oxide, e.g. magnetite, or a ferrite such as cobalt, nickel or manganese ferrites.
The examples below are non-limiting and are merely representative of various aspects and features of the present invention.
Magnetic nanoparticles for drug deliver or magnetic labeling of tumors always flow inside the vessel. In order to simulate this bio-condition, the capillary of 0.9 mm in inner diameter similar with the vessel size of human beings and 2 cm in length was used to fill the magnetic fluids, and then placed in the polystyrene cavity and covered by the pig skin of 2 mm thickness, as shown in
In another consideration, the measured magnetic signal always is necessarily mapped onto the torso for the surgery information. For example, the research on integrated MEG/MRI emerges recently (Zotev V S, et al., “Microtesla MRI of the human brain combined with MEG,” J. Magn. Reson. 194 115, 2008). Therefore the aluminum foil as the reference is pasted on the polystyrene plate in 3 cm distance from the capillary. It simulated the future clinic examination way that the probe scans around the contours of the torso with some pasted aluminum foils on the skin to find out the relative position of injected bio-function magnetic nanoparticles bound to the bio-target within the torso.
After controlling the distance between the probe and the pig skin, the probe scanned the pig skin in the speed of 2 mm/s in x direction for one round trip by X-Y stepper motor. And the step in y direction was 1.5 cm due to the spatial resolution around 1.1 cm.
The typical scanning pattern, i.e. the variation of B0° and B90° with the scanning path, is as shown in
By constructing the scanning pattern of B0° and B90°, magnetic images are presented as
In magnetic labeling application, the bio-function magnetic nanoparticles, flowing in the blood vessel or injected in the well plate, are bound to the tumor or bio-targets if those touch the targets. After binding to the bio-targets, the magnetic nanoparticles could not rotate free and results in the reduction of AC susceptibility. The larger the tumor size or the more bio-target proteins, the more the bound nanoparticles. Magneto reduction assay is based on the way to determine the biotarget amount by the reduction percentage (J. J. Chieh et al., “Hyper-high-sensitivity wash-free magnetoreduction assay on biomolecules using high-Tc superconducting quantum interference devices”, J. Appl. Phys., 03, 014703-1˜6, 2008). Beyond tracking these particles, in order to valid the feasibility of monitoring the dynamic of those particles like a bio junction process by this instrument, the ex-vivo immunoassay was performed, too. A hole of 1 cm in diameter drilled in the acrylic plate of 2 cm thick was filled with anti-CRP coating magnetic fluids with the concentration of 0.1 emu/g and 0.8 c.c. and CRP solution of 0.1 mg/L and 0.1 c.c. initially and sealed by transparent thin-film. At first, the distance between the probe and the hole is controlled at 2 mm apart. By scanning across the filled hole, the best position for the largest amplitude of B0° and B90° was found to position the probe for the static measurement in long-term period.
Following the measurement of the tiny field variation of bio junction process, the sensitivity of the instrument is necessarily quantified. The cylindrical holes with the diameters from 0.5 mm to 1 mm and the depth of 2 mm are filled with magnetic fluids with different concentrations. The minimum amount of the detectable magnetic nanoparticles, determined from the product of the magnetic-fluid concentration and the hole volume, at different distances is used as an indicator. Here, the detectable signal is defined as SNR larger than 2.
If all theses magnetic particles could be bound to prostate tumor or breast tumor, the minimum detected sizes of the prostate tumor or breast tumor is 0.38 mm and 0.17 mm in diameter in depth of 1 cm, separately, by the information of 33000 and 330000 magnetic particles for each prostate and breast tumor cell. In other words, the high sensitivity for the breast tumor of 1.16 mm in size and 3 cm in depth is feasible and better than the current clinic examination (Mital M. and Pidaparti M. R., “Breast Tumor Simulation and Parameters Estimation Using Evolutionary Algorithms,” Journal of Modelling and Simulation in Engineering 2008, 756436, 2008). Besides, based on the sensitivity of this depth and the volume, the skin tumor is also undoubtedly examined well because the skin tumor in early stage is as large as 0.76 mm in diameter and located in the depth deeper than 1.4 mm (Marks R, “An overview of skin cancers,” Cancer, 75, 607, 1995 and Lavker M. R., et al., “Hair follicle stem cells: Their location, role, in hair cycle, and involvement in skin tumor formation,” J. Invest. Dermatol. 101 16S, 1993).
In order to demonstrate no influence of the susceptibility of bloods, tissues, etc. on the measurement of magnetic nanoparticles within the torso, the in-vivo test of injecting magnetic fluids was executed by the probe over the studying organs of individual rat. So the position of studying organs was necessarily pointed out onto the rat torso at first by some steps. The xiphoid, representative of the boundary between the thoracic cavity and abdominal cavity, was marked onto the anesthetized rat, as shown in
By scanning across the specific organ along the relative coordinate line in advance, the scanning pattern of the specific organ could be found as shown in