Abstract:
Provided are a biomolecule detection device, a mobile phone for biomolecule detection, and a biomolecule detection method. The biomolecule detection device includes an electrophoresis unit comprising an electrophoretic gel filtering erythrocytes and leukocytes in blood and transferring proteins and DNAs in the blood, and at least one type of a probe biomolecule, immobilized in the electrophoretic gel, reacting with a target biomolecule; a conversion unit converting a result of a reaction between the target biomolecule and the probe biomolecule to an electrical signal; and a lead-out unit receiving, converting, and transmitting the electrical signal.

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATION 
     This application claims priority from Korean Patent Application No. 10-2005-0120115, filed on Dec. 8, 2005, and No. 10-2006-0056531, filed on Jun. 22, 2006, in the Korean Intellectual Property Office, the disclosures of which are incorporated herein in their entireties by reference. 
     FIELD OF INVENTION 
     The present invention relates to a biomolecule detection device, a mobile phone for biomolecule detection, and a biomolecule detection method. 
     DESCRIPTION OF THE RELATED ART 
     Electrophoresis is a molecular biological assay that separates molecules in a sample based on molecular size and conformation and an isoelectric point by placing a matrix material with a microstructure, such as an agarose or polyacrylamide gel, in an electrolyte buffer solution and generating an electric field between opposite electrodes. Target molecules may be single-molecules such as DNAs, RNAs, or proteins, or if desired, may also be complex molecules such as DNA-protein complexes or DNA-RNA complexes. 
     Generally, a voltage of fifty to several hundreds or thousands of volts may be applied across opposite ends of an electrophoretic system. However, if an area under the influence of an electric field, i.e., an area of a space where an electrolyte is filled is small, electrophoresis can occur even at a voltage of several volts. 
     During electrophoresis, a molecular mixture in a sample is separated into its components according to a frictional force between the components and pores of a matrix structure while it migrates toward the bottom of a gel by the flow of an electrolyte solvent and the attraction and repulsion between two opposite electrodes. For example, electrophoretic separation can be performed on the basis of the molecular size or conformation of DNA, the molecular weight or three-dimensional structure of protein, etc. 
     Recently, two-dimensional (2D) electrophoresis is used to achieve more precise separation of a protein mixture into individual proteins. In 2D electrophoresis, proteins are separated according to their molecular weights (primary separation) followed by their isoelectric points (secondary separation), and thus, it is possible to distribute the proteins in a 2D plane according to each kind of protein. In particular, the 2D electrophoresis is very useful in the identification of disease-associated protein markers and physiological research. 
     Most protein analyses for diagnostics such as blood typing, pregnancy testing, detection of hepatitis, and immunodetection are based on antigen-antibody interactions. Antigen-antibody interaction-based assays have been widely used in diagnostics due to high specificity, high stability upon lyophilization, application of well-known immobilization techniques, etc. 
     In antigen-antibody interaction-based assays, a capturing antibody is immobilized on a solid phase, and a fluorescence- or enzyme-linked primary antibody is incubated with a sample. When the sample moves by transfer of a mobile phase, an antigen in the sample is bound to the capturing antibody and concentrated, thereby resulting in color development by a fluorophore or chromophore reagent. 
     Hitherto, there is no report about a mobile phone that can be used for the diagnostic detection of disease regardless of time and place and for remote medical consultation. 
     SUMMARY OF THE INVENTION 
     The present invention provides a biomolecule detection device that can be used for biomolecule detection (e.g., self-diagnosis of disease) regardless of time and place. 
     The present invention also provides a mobile phone for biomolecule detection that can be used for biomolecule detection (e.g., self-diagnosis of disease) regardless of time and place, and at the same time, can transmit the detection results to a medically trained person (e.g., a doctor) and receive the medical consultation wirelessly. 
     The present invention also provides a biomolecule detection method capable of performing biomolecule detection (e.g., self-diagnosis of disease) regardless of time and place, and transmitting the detection results to a medically trained person (e.g., a doctor) and receiving the medical consultation wirelessly. 
     According to an aspect of the present invention, there is provided a biomolecule detection device including: an electrophoresis unit including an electrophoretic gel, and at least one type of a probe biomolecule, immobilized in the electrophoretic gel, reacting with a target biomolecule; a conversion unit converting a result of a reaction between the target biomolecule and the probe biomolecule to an electrical signal; and a lead-out unit receiving, converting, and transmitting the electrical signal. 
     The electrophoresis unit may further include a filter filtering the sample. 
     The electrophoresis unit may further include a sample inlet. 
     The electrophoresis unit may further include an electrode generating an electric field necessary for electrophoresis. 
     The electrophoresis unit may further include a polymer material which is disposed in the electrophoretic gel and immobilizes the probe biomolecule. 
     The electrophoresis unit may further include a microchannel including the electrophoretic gel and the probe biomolecule. 
     The electrophoresis unit may further include a detecting probe biomolecule conjugated with a gold colloid. 
     The electrophoretic gel may be an agarose gel or a polyacrylamide gel. 
     The target biomolecule and the probe biomolecule may be each a nucleic acid or a protein. 
     The nucleic acid may be selected from the group consisting of DNAs, RNAs, PNAs, LNAs, and hybrids thereof. 
     The protein may be selected from the group consisting of enzymes, substrates, antigens, antibodies, ligands, aptamers, and receptors. 
     The target biomolecule and the probe biomolecule may be respectively an antigen and an antibody or a target DNA and a probe DNA. 
     The electrophoresis unit may further include two substrates facing each other, and the electrophoretic gel and the probe biomolecule may be interposed between the two substrates. 
     The two substrates may be made of a transparent material. 
     The conversion unit may be a photodiode array. 
     The photodiode array may be a photodiode array capable of detecting visible light or UV light. 
     According to another aspect of the present invention, there is provided a mobile phone for biomolecule detection, including: an electrophoresis unit including an electrophoretic gel, and at least one type of a probe biomolecule, immobilized in the electrophoretic gel, reacting with a target biomolecule; a conversion unit converting a result of a reaction between the target biomolecule and the probe biomolecule to an electrical signal; a lead-out unit receiving, converting, and transmitting the electrical signal; a power supply unit supplying power to the electrophoresis unit, the conversion unit, and the lead-out unit; an optical source irradiating light to the electrophoresis unit; and a transmitter transmitting information received from the lead-out unit wirelessly. 
     The optical source may be an LCD screen of the mobile phone. 
     The optical source may further include a UV light source. 
     According to still another aspect of the present invention, there is provided a method of detecting a target biomolecule using a mobile phone for biomolecule detection, the mobile phone including an electrophoresis unit including an electrophoretic gel, and at least one type of a probe biomolecule, immobilized in the electrophoretic gel, reacting with a target biomolecule; a conversion unit converting a result of a reaction between the target biomolecule and the probe biomolecule to an electrical signal; a lead-out unit receiving, converting, and transmitting the electrical signal; a power supply unit supplying power to the electrophoresis unit, the conversion unit, and the lead-out unit; an optical source irradiating light to the electrophoresis unit; and a transmitter transmitting information received from the lead-out unit wirelessly, the method including: loading a sample on the electrophoresis unit to perform electrophoresis; irradiating light to the electrophoresis unit using the optical source; and transmitting the detection result wirelessly. 
     The method may further include mixing the sample with a solution including a molecule capable of binding with the target biomolecule and absorbing light emitted from the optical source or a molecule capable of binding with the target biomolecule, absorbing light emitted from the optical source, and emitting light with a predetermined wavelength, prior to loading the sample on the electrophoresis unit. 
     The sample may be selected from the group consisting of saliva, urine, blood, serum, cell culture, and drinking water. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other features and advantages of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings in which: 
         FIG. 1  is a block diagram illustrating a biomolecule detection device according to an embodiment of the present invention and a mobile phone for biomolecule detection including the device; 
         FIG. 2  is an exploded perspective view schematically illustrating a biomolecule detection device according to an embodiment of the present invention and a mobile phone for biomolecule detection including the device; 
         FIG. 3  is a schematic view illustrating the conversion of biomolecule detection results obtained using light to electrical signals and the wireless transmission of the electrical signals; 
         FIG. 4  is a schematic view illustrating a process of detecting liver cancer using a biomolecule detection device according to the present invention; 
         FIG. 5  illustrates a photodiode array-detected voltage in a case where a target biomolecule is absent in a sample; 
         FIG. 6  illustrates a photodiode array-detected voltage in a case where a target biomolecule is present in a sample; 
         FIG. 7  is a view illustrating a biomolecule detection device according to another embodiment of the present invention and a mobile phone for biomolecule detection including the device; 
         FIG. 8  is a detailed view of an electrophoresis unit of the biomolecule detection device illustrated in  FIG. 7 ; and 
         FIG. 9  is a view illustrating a biomolecule detection device according to still another embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention will now be described more fully with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. 
       FIG. 1  is a block diagram illustrating a biomolecule detection device according to an embodiment of the present invention and a mobile phone for biomolecule detection including the device. 
     Referring to  FIG. 1 , a mobile phone for biomolecule detection includes a biomolecule detection device  11 , a mobile phone body  12 , and a power supply unit  13 . 
     The biomolecule detection device  11  includes an electrophoresis unit  111 , a conversion unit  112 , and a lead-out unit  113 . The electrophoresis unit  111  includes a filter  1111  for filtering a sample  14  introduced through a sample inlet (not shown), an electrophoretic gel  1112 , and first, second, and third antibodies  1113 ,  1114 , and  1115 , immobilized on the electrophoretic gel  1112 , reacting with specific antigens. 
     The electrophoretic gel  1112  is used for two purposes: (1) for filtering blood cells (erythrocytes and leukocytes) in blood by adjusting a pore size of the gel  1112  to detect marker proteins or DNAs in the blood and (2) for use as a transfer medium of proteins or DNAs in an electric field. 
     The conversion unit  112  converts antigen-antibody interaction results to electrical signals. The conversion unit  112  may be a photodiode array, and the photodiode array may be a photodiode array capable of detecting visible/UV light. The lead-out unit  113  receives the electrical signals from the conversion unit  112  and converts and transmits the received signals. 
     The mobile phone body  12  includes an optical source  121  and a transmitter  122 . The optical source  121  irradiates light to the electrophoresis unit  111 . An LCD screen equipped in the mobile phone body  12  may be used as the optical source  121 . In addition to the LCD screen, a UV light source may be further used. The transmitter  122  receives information from the lead-out unit  113  and transmits the received information to a hospital (or a doctor)  15  wirelessly. 
     The power supply unit  13  supplies a power to the mobile phone body  12 , and the electrophoresis unit  111 , the conversion unit  112 , and the lead-out unit  113  of the biomolecule detection device  11 . A conventional battery that can be installed in the mobile phone body  12  may be used as the power supply unit  13 . 
     In the present invention, a biomolecule may be a nucleic acid or a protein. The nucleic acid may be selected from the group consisting of DNAs, RNAs, PNAs, LNAs, and hybrids thereof, and the protein may be selected from the group consisting of enzymes, substrates, antigens, antibodies, ligands, aptamers, and receptors. In the present invention, a target biomolecule and a probe biomolecule may be respectively an antigen and an antibody or a target DNA and a probe DNA. 
       FIG. 2  is an exploded perspective view schematically illustrating a biomolecule detection device according to an embodiment of the present invention and a mobile phone for biomolecule detection including the device. 
     Referring to  FIG. 2 , a mobile phone body  22  includes an LCD screen  221 , a cover  223 , and a keypad  224  equipped with a battery  23  used as a power supply source. A biomolecule detection chip  21  is attached onto the keypad  224 . 
     Since a low-voltage battery such as a mobile phone battery is used in a biomolecule detection device according to the present invention, an area of a buffer filling part which is under the influence of an electric field in the biomolecule detection device must be minimized. Thus, the buffer filling part may be in the form of a capillary microchannel or a thin plate. Although the buffer filling part can be filled with only a buffer, it may also be packed with a homogeneous gel matrix such as agarose, polyacrylamide, or silica, in order to increase a contact time of a sample with a probe biomolecule. 
     An electrophoresis unit of the biomolecule detection chip  21  includes two substrates  2116  and  2117  facing each other. An electrophoretic gel  2112  and first, second, and third antibodies  2113 ,  2114 , and  2115  are interposed between the two substrates  2116  and  2117 . The substrates  2116  and  2117  may be made of a transparent material to allow visible/UV light to be transmitted therethrough. The number of types of antibodies is not particularly limited and may be variously determined according to the purpose of detection. 
     In order to measure the quantity of light in each antibody region, photodiodes  2121  are broadly arranged under the substrate  2117  to form a photodiode array  212 , and thus, the photodiode array  212  has an area corresponding to the total area of the electrophoretic gel  2112  including all the antibody regions. A lead-out circuit (not shown) for measuring the voltage distribution along the photodiode array  212  is disposed around the photodiode array  212 . 
       FIG. 3  is a schematic view illustrating the conversion of biomolecule detection results obtained using light to electrical signals and the wireless transmission of the electrical signals. 
     Referring to  FIG. 3 , in order to determine if a target biomolecule is present in a sample, the sample is mixed with a solution including a molecule capable of binding with the target biomolecule and absorbing light emitted from an optical source or a molecule capable of binding with the target biomolecule, absorbing light emitted from the optical source, and emitting light with a predetermined wavelength, and the resultant sample solution  34  is loaded on a filter (not shown) of an electrophoresis unit  311 . The filter may be a top portion of a gel on which the sample solution  34  is loaded, or alternatively, a device which is separately disposed on top of the gel for separating blood cells. In the present invention, it is possible to prevent blood cells from entering into a gel by adjusting the pore size of the gel. Thus, there is no need to separately perform the separation of blood cells from blood. 
     After the sample solution  34  loaded on the gel passes through the last antibody region, a cover of a mobile phone is closed, and then, light  321 , e.g., white light emitted from LCD or UV light emitted from a UV source disposed at the cover of the mobile phone is irradiated to the electrophoresis unit  311 . At this time, antigen-antibody interaction may occur in each antibody region. If a predetermined antigen is absent in a sample, antigen-antibody interaction may not occur in a predetermined antibody region. In the present invention, in order to attach a side-chain molecule capable of absorbing visible/UV light to an antigen protein in blood, a mixture of a protein dye, gold particles, or a fluorophore reagent with initial blood is loaded on a gel. 
     The quantity of light that passes through each antibody region is changed according to the degree of antigen-antibody interaction. Thus, the amount of current flowing in photodiodes  3121  of a photodiode array  312  disposed under the electrophoresis unit  311  is changed. The amount of current is read as a voltage distribution by a lead-out unit  313  disposed around the photodiode array  312 . The voltage values are transmitted to a terminal  35  of a (hospital) doctor via a transmitter  322 . The doctor can analyze the received data and then feedback the doctor&#39;s observations and diagnosis to an individual. 
       FIG. 4  is a schematic view illustrating a process of detecting liver cancer using a biomolecule detection device according to the present invention. 
     Alphafetoprotein (AFP) is a protein found in liver cancer patients. AFP is also expressed in normal persons suffering from inflammations. Meanwhile, the addition of fucose to AFT by post translational modification generates AFP-L 3 . AFP-L 3  is known as a liver cancer marker protein that is significantly detected in patients suffering from liver cancer. 
     Referring to  FIG. 4 , an electrophoresis unit  411  includes a microchannel which includes an AFP-detecting antibody region  4113  including an AFP-detecting antibody  41131 . The microchannel is branched into two sub-microchannels respectively including an anti-AFP antibody immobilization region  4114  immobilized with an AFP-binding antibody  41141  and an anti-AFP-L 3  antibody immobilization region  4115  immobilized with an AFP-L 3 -binding antibody  41151 . The AFP-detecting antibody  41131  can bind with an antigen labeled with a protein-attachable dye such as fluorophore or gold colloid. The protein-attachable dye promotes AFP detection by absorbing visible/UV light. The AFP-L 3 -binding antibody  41151  may be fucose-reactive lectin. 
     When a sample  44  containing an AFP  441  and an AFP-L 3   442  is loaded in the microchannel, the AFP  441  and the AFP-L 3   442  are bound to the AFP-detecting antibody  41131 , and two equal volumes of the sample solution containing an AFP-AFP-detecting antibody complex  443  and an AFP-L 3 -AFP-detecting antibody complex  444  are respectively allowed to pass through the two sub-microchannels. In the two sub-microchannels, the AFP-AFP-detecting antibody complex  443  and the AFP-L 3 -AFP-detecting antibody complex  444  are respectively bound to the AFP-binding antibody  41141  and the AFP-L 3 -binding antibody  41151 . The strengths of signals generated from the two sub-microchannels are analyzed for the detection of liver cancer. 
       FIG. 5  illustrates a photodiode array-detected voltage in a case where a target biomolecule is absent in a sample. 
     Referring to  FIG. 5 , an electrophoresis unit  511  includes a first antibody immobilization region  5113 , a second antibody immobilization region  5114 , and a third antibody immobilization region  5115 . The first antibody immobilization region  5113  includes a gel in which a first antibody  51132  is immobilized in a microstructural network of glass fiber or polymer  51131 . A second antibody  51142  and a third antibody  51152  are respectively immobilized in the second antibody immobilization region  5114  and the third antibody immobilization region  5115  in the same manner as above. A sample solution  55  obtained by mixing a sample with a predetermined molecule capable of binding with a predetermined antigen and absorbing visible/UV light is loaded in the electrophoresis unit  511 . 
     While the sample solution  55  passes through the electrophoresis unit  511 , macromolecules (e.g., blood cells) are filtered out through a filter (not shown). In the first antibody immobilization region  5113 , an antigen (i.e., a first antigen) capable of undergoing an antigen-antibody interaction with the first antibody  51132  is bound to the first antibody  51132 , and the remaining sample solution migrates by electrophoresis toward the second antibody region  5114 . In the second antibody region  5114 , an antigen (i.e., a second antigen) capable of undergoing an antigen-antibody interaction with the second antibody  51142  is bound to the second antibody  51142 , and the remaining sample solution migrates by electrophoresis toward the third antibody region  5115 . The same electrophoresis as above is performed in the third antibody region  5115 . 
     Meanwhile, an antigen used as a marker protein capable of binding with an antibody may be absent in an initial sample. In this case, an antigen-antibody interaction does not occur. In the present invention, a marker protein in an initial sample is linked with a molecule capable of absorbing visible/UV light. Thus, if an antigen-antibody interaction event has occurred in an antibody immobilization region, light absorption by the molecule will occur in the antibody immobilization region. 
     As shown in  FIG. 5 , if marker proteins capable of binding with antibodies are absent in an initial sample, photodiodes disposed below the antibodies will mostly absorb incident visible/UV light, except visible/UV light absorbed by glass fiber or polymer components.  FIG. 5  illustrates a voltage distribution in a case where marker proteins for the first, second, and third antibodies  51132 ,  51142 , and  51152  are absent in the sample  55 . 
       FIG. 6  illustrates a photodiode array-detected voltage in a case where a target biomolecule is present in a sample. 
     Referring to  FIG. 6 , an electrophoresis unit  611  has the same structure as the electrophoresis unit illustrated in  FIG. 5 . If a biomarker protein in a sample reacts with an antibody, absorption of visible/UV light directly proportional to the number of the biomarker protein molecules will occur. 
       FIG. 6  illustrates that no antigen-antibody interaction has occurred in a first antibody region  6113 , much interaction has occurred between antigens and antibodies in a second antibody region  6114 , and less interaction has occurred between antigens and antibodies in a third antibody region  6115 . Thus, zero voltage is measured in the first antibody region  6113 , a higher voltage is measured in the second antibody region  6114 , and a lower voltage is measured in the third antibody region  6115 . That is,  FIG. 6  illustrates that marker proteins (antigens) for second and third antibodies are present in a sample. 
     With respect to the voltage measurement principle, when a marker protein linked with a molecule capable of absorbing visible/UV light emitted from an optical source is bound to an antibody specific to the marker protein, absorption of visible/UV light directly proportional to the number of the marker protein molecules occurs, thereby reducing the number of photons reaching the underlying photodiodes. 
     If the number of photons is reduced, the amount of current flowing between two electrodes in each photodiode is reduced, thereby increasing a voltage across the two electrodes. 
       FIG. 7  is a view illustrating a biomolecule detection device according to another embodiment of the present invention and a mobile phone for biomolecule detection including the device. 
     Referring to  FIG. 7 , the width and thickness of a biomolecule detection device  71  are similar to those of a mobile phone body  72 . The biomolecule detection device  71  is attached to a side of the mobile phone body  72 , and includes electrodes  711  and  712 , a sample inlet  713 , a filter  714 , and a microchannel  715 . A control antibody region  716  and a capturing antibody region  717  are disposed in the microchannel  715 . The sample inlet  713  is usually plugged to prevent internal contamination of the biomolecule detection device  71 . In a case where the biomolecule detection device  71  contains a matrix such as a gel, the sample inlet  713  serves to prevent the evaporation of internal moisture. The electrodes  711  and  712  are respectively matched to electrodes  721  and  722  disposed at the side of the mobile phone body  72 . 
       FIG. 8  is a detailed view of an electrophoresis unit of the biomolecule detection device illustrated in  FIG. 7 . 
     Referring to  FIG. 8 , a detecting antibody  818  conjugated with a gold colloid is patched around a sample inlet  814 . When a sample is loaded, the detecting antibody  818  is dissolved by moisture contained in the sample and then reacts with a target biomolecule in the sample. A control antibody  8162  and a capturing antibody  8172  may be directly immobilized on the bottom of a channel. However, it is preferred that the control antibody  8162  and the capturing antibody  8172  are immobilized on polymer materials  8161  and  8171  such as glass fibers or polysaccharides. Therefore, antibody immobilization efficiency can be increased, thereby increasing detection sensitivity. 
     In the case of using a gold colloid, the presence of a target biomolecule can be visually detected by color change. In this case, there is no need to use photodiodes. 
       FIG. 9  is a view illustrating a biomolecule detection device according to still another embodiment of the present invention. 
     Referring to  FIG. 9 , a nucleic acid such as DNA or RNA is used as a biomolecule. A labeled target nucleic acid  94  is loaded into a sample inlet  914 , and probe nucleic acids  915 ,  916 , and  917  are immobilized in a biomolecule detection device  91 . The biomolecule detection device  91  can be used for genotyping, gene identification, gene expression profiling, etc. 
     Data transmission can be achieved through a photodiode array (not shown) disposed below the probe nucleic acids  915 ,  916 , and  917 . When performing single-nucleotide polymorphism (SNP) analysis for probe nucleic acids with only a 1-bp difference, non-specific DNAs or chemical materials can also be used to induce more specific hybridization. For example, salmon sperm DNA or Ficoll can be used. The number of probe nucleic acids to be used can be determined according to the purpose of detection. 
     The present invention also provides a method of detecting a target biomolecule using a mobile phone for biomolecule detection according to the present invention. The target biomolecule detection method includes: loading a sample on an electrophoresis unit to perform electrophoresis; irradiating light to the electrophoresis unit using an optical source; and transmitting the detection results wirelessly. 
     The target biomolecule detection method may further include mixing the sample with a solution including a molecule capable of binding with the target biomolecule and absorbing light emitted from the optical source or a molecule capable of binding with the target biomolecule, absorbing light emitted from the optical source, and emitting light with a predetermined wavelength, prior to loading the sample on the electrophoresis unit. 
     The type of the sample is not particularly limited. For example, the sample may be selected from the group consisting of saliva, urine, blood, serum, cell culture, and drinking water. 
     While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims. 
     As described above, a biomolecule detection device according to the present inventiona can be used for biomolecule detection (e.g., self-diagnosis of disease) regardless of time and place. A mobile phone for biomolecule detection according to the present invention can be used for biomolecule detection (e.g., self-diagnosis of disease) regardless of time and place, and at the same time, can transmit the detection results to a medically trained person (e.g., a doctor) and receive the medical consultation wirelessly. A biomolecule detection method according to the present invention can be used to perform biomolecule detection (e.g., self-diagnosis of disease) regardless of time and place, and transmit the detection results to a medically trained person (e.g., a doctor) and receive the medical consultation wirelessly.