Patent Publication Number: US-2004043385-A1

Title: Microarray biochip

Description:
FIELD OF THE INVENTION  
       [0001] The present invention relates to a microarray biochip and particularly to a biochip for use in the detection of nucleic acids, proteins or other biological molecules.  
       BACKGROUND OF THE INVENTION  
       [0002] Biochips mainly are used based on specificity existed between biological molecules. Biological probes (mainly include nucleic acids, proteins, carbonhydrates, cells, tissues or the likes) are immobilized on a specific substrate, then biological sample solution (such as blood, urine, body fluid, or saliva) to be tested is applied and mixed on the biochip. The targets in the sample solution can react with the biological probes on the substrate to form the target-probe complex. Then a signal transducer or a detection device may be used to detect the target-probe complex and to process optical, piezoelectric or electrochemical quantitation or image analyses to obtain biological analysis information of the testing samples.  
       [0003] At present there are generally two types of substrates for the immobilization of biological probes on the biochip: (a) one adopts opaque substrates such as polymer films (such as Nylon films) or glass slides evaporating with metal films; (b) another one adopts transparent substrates such as blank glass slides. However, they still have problems when put to practical use, notably:  
       [0004] 1. in the (a) type substrates, the metal film (such as gold film) with biological compatibility can form a covalent bonding with a linker or with the probe, and opaque substrates such as Nylon film may also form a covalent bonding through chemical or physical methods (such as Ultraviolet cross-linking). However, these substrates do not allow light to pass through, transmittant scanners such as calorimetric or fluorometric types, or microscopes cannot be used for detection. Only reflective detection devices can be used. The restriction of detection device applicability limits adaptability of some low-cost detection techniques usually used in common laboratory;  
       [0005] 2. the (b) type substrates are transparent and can be used in optical detecting devices such as transmittant or reflective scanners or microscopes for doing image analysis and comparison. However, it is often restricted by immobilization method used and its lower immobilization capacity. Also, it requires pre-preparation steps and washing could cause probe leakage and result in errors in qualitative and quantitative analyses;  
       [0006] 3. the biochips made by the methods of (a) and (b) types cannot effectively hold end products that retain mark information during marking and testing operations. For instance, when applying on the ELISA testing techniques used in biochips, the chromophore or fluorescent products obtained after enzymatic catalysis are difficult to stay on the substrate when the surface of the biochip are washed or the biochip is moved for detection. As a result, the reading of test results tend to incur errors.  
       SUMMARY OF THE INVENTION  
       [0007] Therefore the primary object of the invention is to resolve aforesaid disadvantages. The invention provides a microarray biochip that can firmly and securely hold probes, and has great adaptability for detection devices, and can effectively carry and retain end products.  
       [0008] In order to achieve the foregoing objects, the microarray biochip of the invention includes a transparent substrate which has at least one indented reaction zone. In the reaction zone, there are a plurality of solid or hollow adhesive units. Each solid or hollow adhesive unit has a preset height and affinity to biological molecules, and a top surface and lateral surfaces to form respectively a first adhesive surface and second adhesive surfaces for the immobilization of probes. Thereby the reaction zone may hold sample solution and keep the end mark products. The second adhesive surfaces may provide the probes with the immobilization area for use in transmittant detection. Through the transparent substrate and the spaced adhesive units, it can be adopted for use in optical transmittant or reflective detection device and in calorimetric or fluorometric type of experiments.  
       [0009] The foregoing, as well as additional objects, features and advantages of the invention will be more readily apparent from the following detailed description, which proceeds with reference to the accompanying drawings. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0010]FIG. 1 is a plain view of the invention.  
     [0011]FIG. 2-A is a schematic view of the invention.  
     [0012]FIG. 2-B is a fragmentary enlarged view of FIG. 2-A.  
     [0013]FIG. 3 is a schematic view of the invention in use.  
     [0014]FIG. 4-A is a schematic view of another embodiment of the invention.  
     [0015]FIG. 4-B is a cross section of FIG. 4-A.  
     [0016]FIG. 4-C is a fragmentary enlarged view of FIG. 4-B.  
     [0017]FIG. 4-D is a schematic view of catalytic reaction according to FIG. 4-C.  
     [0018]FIG. 5 is a schematic view of an embodiment of the invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
     [0019] Referring to FIGS.  1 ,  2 -A and  2 -B, the microarray biochip of the invention aims at employing specificity between biological molecules to immobilize selected biological molecules on a substrate  10  to form biological probes  50  to interact with corresponding target molecules  61  in test sample solution  60  to generate signals to facilitate readings and analysis for detection device. The microarray biochip of the invention includes a transparent substrate  10  which contains at least one reaction zone  20 . In the reaction zone  20 , there are a plurality of solid or hollow adhesive units  30 . Each solid or hollow adhesive units  30  has a preset height, and a top surface and lateral side surfaces to form respectively a first adhesive surface  31  and second adhesive surfaces  32 . The second adhesive surfaces  32  may provide the probes  51  with the immobilization area for use in optical transmittant detection. The gaps between the adhesive units  30  can effectively retain end label products  72  after enzyme  70 -catalyted reaction, and through the transparent substrate  10  the biochip allow transmittant type or reflective type of detection device to process reading and analysis of signals.  
     [0020] The substrate  10  is made from glass or other transparent materials. The reaction zone  20  may be formed on the substrate  10  in a matrix configuration, and may be formed in circular, rectangular, or other geometric shapes. Moreover, the adhesive units  30  are made of materials with a great biological compatibility, such as gold, silver, nickel, silicon or copper, preferably gold. The adhesive units  30  may be solid and have a cross section in a shape of a circular, a rectangular or a selected geometric shape. The adhesive units  30  may be hollow and have a cross section with an outer shape of a circular, a rectangular or a selected geometric shape, and with an inner shape of a circular, a rectangular or a selected geometric shape.  
     [0021] During manufacturing, the adhesive unit  30  and an interface layer  40  between the adhesive unit  30  and the substrate  10  may be formed by employing Micro Electro Mechanical System (MEMS) or nanolithography techniques. The adhesive units  30  are laid and distributed in a spaced and matrix fashion with a selected interval formed therebetween on the reaction zone  20 . The spaced interval may be 0.1, 1, 10 or 100 ì m, preferably the smaller ones for increasing the area of the first and the second adhesive surfaces. The adhesive units  30  has a preset height of at least 10 nm to allow the lateral second adhesive surfaces  32  having sufficient immobilization surface for biological molecules. The height may be 10, 50, 100, 500 or 1000 nm, preferably smaller than to the interval of the adhesive units  30 .  
     [0022] Referring to FIG. 3, when the invention is in use, apply sample solution  60  on the reaction zone  20 . The sample solution  60  contains target molecules  61  which conjugates with molecular label  62  (such as fluorescent material fluororecine). The target molecules  61  then start interaction with biological probes  50  which are immobilized to the first and second adhering surfaces  31  and  32 . And the molecular label  62  conjugated to the target  61  can generate signal information. The signal information on the first adhesive surface  31  and the second adhesive  32  may be respectively fed to the optical reflective and transmittant type of detection devices to process reading and analysis operations.  
     [0023] Refer to FIGS.  4 -A,  4 -B,  4 -C and  4 -D for another embodiment of the invention, with FIG. 4-A showing a schematic view, FIG. 4-B showing a cross section, FIG. 4-C showing a fragmentary enlarged view, and FIG. 4-D showing a catalytic reaction. The reaction zone  20  is an indented recess formed on the substrate  10 ′ with a fall distance  11  for holding sample solution  60 . The fall distance  11  may prevent the biological probes  50  from damaging when the sample solution  60  is withdrawn. In addition, when applying Enzyme-linked Immunosorbent Assay (ELISA) techniques, substrate  71  that has been catalyzed by enzyme  70  may generate end product  72  with colorimetric or fluorescent property, and the end product  72  may be retained in the fall distance  11 . Thereby the end product  72  may be retained without losing when the biochip is moved for detection, and test results can be properly obtained without being affected.  
     [0024] Refer to FIG. 5 for an embodiment of the invention. The reaction zones  20  on the substrate  10  may be configured in a matrix fashion by 2×2, 3×3, 4×4, or 5×5 patterns. The intervals between the reaction zones  20  may be designed and set to match existing arrayer or sample-loading apparatus.