Abstract:
A lateral flow immunoassay test device is provided that includes a housing with an elongated slot for holding a test sample collector; an elongated holder member for securing at least one immunoassay test strip therein; a first chamber for storing a first, pre-treatment reagent; and a second chamber for storing a second reagent. Methods of conducting lateral flow immunoassays are also provided. The device and methods of conducting lateral flow immunoassays as provided herein are advantageous in that they allow pre-treatment and pre-incubation of the test sample so that the sample flows onto the test strip more easily and provide for increases in the sensitivity of the assay.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a Divisional of U.S. application Ser. No. 10/695,145, filed on Oct. 28, 2003 now U.S. Pat. No. 7,090,803. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention is directed toward a lateral flow immunoassay device and more particularly, toward a test device that allows the sample to be treated and incubated prior to being introduced to the test strip. 
     Immunoassay devices utilizing immunochromatography are often single step devices where a test sample is analyzed for the presence of certain analytes. For example, a specified volume of the sample is contacted with one end of a test strip. The test strip contains colored particles coated with a binder dried on the strip. As the sample is wicked up the test strip, the analyte in the sample reacts with the binder coated on the particles. The test strip also contains antigens in discrete zones. As the reaction mixture flows up the strip, any reaction between the antigens and the analyte, if present, may be observed by the appearance or non-appearance of color in the zones. Often, such tests are used in drug screening. 
     There are several disadvantages to the system described above. For example, once the test sample is introduced, there is no user control over the subsequent events. That is, the fluid flow determines the speed and timing of all of the reactions. Also, if the sample requires pre-treatment with specific reagents to dilute or denature interferants, modify analyte structure, or release analyte from binders, such treatments must be performed outside of the confines of the test device. Therefore, a need exists for a self-contained and simple to use test device that allows control over the test sample so that more accurate test results may be obtained. 
     SUMMARY OF THE INVENTION 
     The present invention is designed to overcome the deficiencies of the prior art discussed above. It is an object of the present invention to provide a self-contained test device that allows the test sample to be pre-treated and pre-incubated. 
     It is another object of the present invention to provide a test device that allows the test sample to flow onto the test strip easily and increases the sensitivity of the assay. 
     In accordance with the illustrative embodiments demonstrating features and advantages of the present invention, there is provided a lateral flow immunoassay test device that includes a housing with an elongated slot for holding a test sample collector; an elongated holder member for securing at least one immunoassay test strip therein; a first chamber for storing a first, pre-treatment reagent; and a second chamber for storing a second reagent such as a binder. The pre-treatment reagent is contained within a rupturable enclosure or receptacle which may be in the form of a bladder. A piercing member is located within the housing that is used to rupture the enclosure in order to release the pre-treatment reagent so that the sample and pre-treatment reagent form a mixture. The binder may then be introduced to the mixture which is allowed to react with the binder for a period of time. The mixture and binder combination is then contacted with the immunoassay test strip. Methods of conducting lateral flow immunoassays are also provided. 
     In one embodiment a button is located in the front side of the housing. When the button is depressed, the piercing member is forced into the enclosure which releases the pre-treatment reagent contained therein. The sample collector is inserted into the housing so that the test sample is placed into contact with the pre-treatment reagent and the sample and pre-treatment reagent mix. The mixture combines with the binder in the manner described above before contacting the test strip. 
     In a second embodiment the sample collector is aligned with the piercing member within the housing. Force is applied to the sample collector which forces the piercing member into contact with the rupturable enclosure, thereby piercing the enclosure. This action, in turn, causes the enclosure to burst so that the pre-treatment reagent is released. The test sample flows through holes formed in the piercing member and mixes with the first reagent. The mixture than combines with the binder in the manner described above before contacting the test strip. 
     In a further embodiment the housing is generally L-shaped with a vertical leg and a horizontal leg extending from the bottom of the vertical leg. The immunoassay test strip is located within the vertical leg. The test sample and first reagent, being mixed as described above, is contacted with the binder in the horizontal leg. In order for the mixture and binder combination to contact the test strip, the housing must be tilted backward so that the vertical leg of the housing becomes the horizontal leg and the horizontal leg becomes the vertical leg. The mixture and binder combination may now flow onto the test strip. 
     Other objects, features, and advantages of the invention will be readily apparent from the following detailed description of preferred embodiments thereof taken in conjunction with the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For the purpose of illustrating the invention, there is shown in the accompanying drawings forms that are presently preferred; it being understood that the invention is not intended to be limited to the precise arrangements and instrumentalities shown. 
         FIG. 1  is a front perspective view of a first embodiment of the present invention; 
         FIG. 2  is a rear perspective view of the first embodiment of the present invention; 
         FIG. 3  is a cross-sectional view of the first embodiment of the present invention; 
         FIG. 4  is a rear perspective view of the interior of the housing of the first embodiment of the present invention; 
         FIG. 5  is a front perspective view of the interior of the housing of the first embodiment of the present invention; 
         FIG. 6  is a front perspective view of a second embodiment of the present invention; 
         FIG. 7  is a cross-sectional view of the second embodiment of the present invention; 
         FIG. 8  is a front perspective view of a third embodiment of the present invention; 
         FIG. 9  is a cross-sectional view of the third embodiment of the present invention; 
         FIG. 10  is front perspective view of a fourth embodiment of the present invention; 
         FIG. 11  is a rear perspective view of the fourth embodiment of the present invention; 
         FIG. 12  is a partial cross-sectional view of the fourth embodiment; and 
         FIG. 13  is an exploded view of the fourth embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to the drawings in detail wherein like reference numerals have been used throughout the various figures to designate like elements, there is shown in  FIG. 1  a lateral flow immunoassay device constructed in accordance with the principles of the present invention and designated generally as  10 . 
     A first embodiment of the present invention is shown in  FIG. 1 . The lateral flow immunoassay device essentially includes a housing  12  with a front side  14 , a rear side  16 , a bottom  18 , and a top  20 . The housing  12  also includes a first chamber  22  for storing a first, pre-treatment reagent  24  and a second chamber  26  for storing a second reagent  28   a  and  28   b . (See  FIGS. 3 and 4 .) Located within the front side  14  of the housing  12  is at least one opening  30  through which a test sample collector  32  may be slidably mounted. The opening  30  leads into an elongated slot  34  with a substantially closed bottom end  36 . However, formed within the closed bottom end  36  is an opening  38  that allows for fluid communication with the second chamber  26 . 
     Also located in the front side  14  of the housing  12  is means  40  for activating the pre-treatment reagent  24 . The activating means  40  fits within the first chamber  22  and may be in the form of a button. Located at the bottom of the first chamber  22  is at least one aperture  44  which enables the first chamber  22  to be in fluid communication with the second chamber  26 . The operation of this button will be discussed in greater detail below. Located in the top  20  of the housing  12  is an elongated slit  46  through which an elongated holder member  48  for securing immunoassay test strips  50   a  and  50   b  may be slidably mounted. The rear side  16  of the housing  12  has a plurality of widows  52  and  54  through which it may be observed whether there is a sufficient amount of the sample mixed with the first reagent and second reagent to be wicked up the test strips. (See  FIG. 2 .) The sample collector  32  may include an elongated member  56  with a swab or sponge  58  located at one end and a handle  60  located at the opposite end. The pre-treatment reagent may be a standard buffer and is contained within a rupturable enclosure in the form of a bladder  62 . The second reagent may be an antigen or a binder such as a colloidal gold-antibody complex, for example. 
     In order to use the device, a test sample is collected on the sponge  58 . The collector  32  is then inserted through the opening  30  and into the slot  34 . As the sponge  58  is forced through the slot  34 , it contacts the opening  38  located at the bottom end  36  of the slot  34 . The test sample is forced through the opening  38  and into the second chamber  26 . Pressure is then applied to the button  40 . Alternatively, the button may be depressed simultaneously with, or before, the sponge is inserted through the slot. Attached to the button  40  is a piercing member  42  that, as force is continued to be placed on the button  40 , comes into contact with the rupturable enclosure  62  and ruptures it. The buffer flows through the aperture  44  located at the bottom of the first chamber  22 . Sample flows through the opening  38  and mixes with the buffer  24 . By adding the buffer to the sample, the buffer allows the sample to flow more easily, thereby increasing the accuracy of the test results. 
     The sample and buffer then flow into the second chamber  26  which is located adjacent the bottom  18  of the housing  12 . The second chamber  26  may have a partition  64  so that two separate compartments  66  and  68  are formed therein with a second reagent  28   a  and  28   b  located in a respective compartment  66  and  68 . (See  FIGS. 4 and 5 .) The partition  64  is formed in such a manner so that the sample and buffer mixture is split into the two compartments  66  and  68 . The second reagent is introduced to the mixture and is allowed to react for a period of time. That is, the reagent and mixture combination is incubated for a period of time. 
     Next, the elongated holder member  48  containing the test strips  50   a  and  50   b  is inserted through the slit  46  and slid downwardly, toward the bottom  18  of the housing  12 . The test strips  50   a  and  50   b  are typical prior art test strips where various antigens are dried thereon that compete with the analyte being tested for a binding site on the antibody. The slit  46  is in fluid communication with the second chamber  26  so that the test strips  50   a  and  50   b  are forced into contact with the mixture and second reagent combination as it is pushed toward the bottom  18  of the housing  12 . Any reactions on the test strips  50   a  and  50   b  may be observed through the window  70 . 
     A second embodiment of the present invention is shown in  FIGS. 6 and 7 . This embodiment is similar in structure and function to the embodiment described above, with the differences discussed below. The device  110  essentially includes a housing  112  with a front side  114 , a rear side  116 , a bottom  118 , and an open top. The housing  112  also includes a first chamber  122  for storing a pre-treatment reagent  124  and a second chamber  126  for storing second reagents, such as binders  128   a  and  128   b . (See  FIG. 7 .) Located within the top of the housing  112  is an opening  130  through which a test sample collector  132  may be slidably mounted and a slot opening  146  through which an elongated holder member  148  for securing immunoassay test strips  150   a  and  150   b  may be slid ably mounted. 
     The pre-treatment reagent is contained within a rupturable enclosure  162 . A piercing member  142  is located within the first chamber  122  that is used to rupture the enclosure  162  in order to release the pre-treatment reagent  124  so that the sample and pre-treatment reagent form a mixture. 
     In order to use the device, the sample is collected on the sponge  158  and the collector  132  is inserted within the slot  134 . The collector  132  is forced through the slot  134  so that is contacts the piercing member  142  which, in turn, ruptures the enclosure  162 . Holes  170  and  172  are formed within the piercing member  142  so that the sample flows therethrough and mixes with the buffer. The sample and buffer mixture then flows through the apertures  144   a  and  144   b  formed in the bottom of the first chamber  122  and contacts the binders  128   a  and  128   b . The second chamber  126  may have a partition  164  so that two separate compartments  166  and  168  are formed therein with a binder  128   a  and  128   b  located in a respective compartment  166  and  168 . The partition  164  is formed in such a manner so that the sample and buffer mixture is split into the two compartments  166  and  168 . The mixture and binder combination is incubated for a period of time. 
     Next, the elongated holder member  148  containing the test strips  150   a  and  150   b  is inserted through the opening  146  and slid downwardly, toward the bottom  118  of the housing  112 . The test strips are typical prior art test strips where various antigens are dried thereon that compete with the analyte being tested for a binding site on the antibody. The slot  146  is in fluid communication with the second chamber  126  so that the test strips  150   a  and  150   b  are forced into contact with the mixture and binder combination as it is pushed toward the bottom  118  of the housing  112 . Any reactions may be observed through the windows  152  and  154 . 
     A third embodiment of the present invention is shown in  FIGS. 8 and 9 . The device  210  is similar in structure and function to the embodiments described above, with the differences discussed below. In this embodiment the housing  212  is generally L-shaped, with a generally horizontal leg  214  and a generally vertical leg  216  with a top end  216   a  and a bottom end  216   b . The horizontal leg  214  extends outwardly from the bottom end  216   b  of the vertical leg  216 . The horizontal leg  214  has an open end  214   a  and an end  214   b  that joins with the vertical leg  216 . The opening  230  for the elongated slot  234  for the sample collector  232  is located at the open end  214   a  of the horizontal leg  214 . 
     As in the second embodiment, the piercing member  242  and first chamber  222  containing the buffer  224  are located within the slot  234 . ( FIG. 9 .) Located within the vertical leg  216  is the test strip holder member  248 . The front of the vertical leg  216  may have windows  252  and  254  formed therein. The second chamber  226  containing the second reagent  228  is in fluid communication with the first chamber  222  via apertures  244 . The second chamber  226 , however, is located adjacent the bottom of the horizontal leg  214 . 
     In order to use the device, the sample is collected on the sponge  258  and the collector  256  is inserted within the slot  234 . The collector  256  is forced through the slot  234  so that is contacts the piercing member  242  which, in turn, ruptures the bladder  262 . Holes  270  and  272  are formed within the piercing member  242  so that the sample flows therethrough and mixes with the buffer. The sample and buffer mixture then flows through the aperture  244  and contacts the second reagent  228 . The mixture and second reagent combination is incubated for a period of time. 
     The horizontal leg  214  is then raised upwardly so that the vertical leg  216  is titled backward. The positions of the horizontal and vertical legs are actually reversed so that the vertical leg is now horizontal and may rest on a flat surface. This action causes the mixture and binder combination to flow through the gap  238  between the second chamber  226  and the slot of the vertical leg  216  within which the test strip is contained. The combination contacts the test strip. Any reactions may be observed through the windows  252  and  254 . 
     A fourth embodiment is shown in  FIGS. 10-13 . The device  310  is similar in structure and function to the embodiments described above, with the differences discussed below. The lateral flow immunoassay device essentially includes a housing  312  with a front side  314 , a rear side  316 , a bottom  318 , and a top  320 . The housing  312  also includes a first chamber  322  for storing a first, pre-treatment reagent  324  and a second chamber  326  for storing a second reagent  328   a  and  328   b . (See  FIGS. 12 and 13 .) Located within the top  320  of the housing  312  is an opening  330  through which a test sample collector  332  may be slidably mounted. The opening  330  leads into an elongated slot  334  with a substantially closed bottom end  336 . However, formed within the closed bottom end  336  is at least one opening  338  that allows for fluid communication with the second chamber  326 . The housing  312  also includes a third chamber  327  which functions in the same manner as chamber  322  and will be described in greater detail below. 
     Also located in the front side  314  of the housing  312  is means  340  for activating the pre-treatment reagent  324 . The activating means  340  fits within the first chamber  322  and may be in the form of a button. While the button  340  is shown protruding from the chamber  322 , it may very well be recessed within the chamber in order to avoid inadvertent activation. Located at the bottom of the first chamber  322  is at least one aperture which enables the first chamber  322  to be in fluid communication with the second chamber  326 . The operation of this button will be discussed in greater detail below. Located in the top  320  of the housing  312  is an elongated slit  346  through which an elongated holder member  348  for securing immunoassay test strips  350   a  and  350   b , for example, may be slidably mounted. (See  FIGS. 11 and 13 .) The rear side  316  of the housing  312  has at least one widow  352  through which any reaction on the test strip may be observed. (See  FIG. 11 .) The sample collector  332  may include an elongated member  356  with a swab or sponge  358  located at one end and a handle  360  located at the opposite end. (See  FIG. 13 .) The pre-treatment reagent may be a standard buffer and is contained within a rupturable enclosure or receptacle  362  which is located within the activating means  340 . The receptacle  362  may be sealed with a rupturable seal  362   a . The second reagent may be an antigen or a binder such as a colloidal gold-antibody complex, for example. 
     In order to use the device, a test sample is collected on the sponge  358 . The collector  332  is then inserted through the opening  330  and into the slot  334 . As the sponge  358  is forced through the slot  334 , it contacts the opening  338  located at the bottom end  336  of the slot  334 . The test sample is forced through the opening  338  and into the second chamber  326 . Pressure is then applied to the button  340  using a tool which may be in the form of an elongated, generally cylindrical handle, such as the collector  332  in an inverted position. Alternatively, the button may be depressed simultaneously with, or before, the sponge is inserted through the slot. Located within the chamber  322  is a piercing member  342  that, as force is continued to be placed on the button  340 , comes into contact with the rupturable seal  362   a  and ruptures it. The buffer flows through an aperture located in the first chamber  322 . Sample flows through the opening  338  and mixes with the buffer  324 . 
     The sample and buffer then flow into the second chamber  326  which is located adjacent the bottom  318  of the housing  312 . The second chamber  326  may have a partition  364  so that two separate compartments  366  and  368  are formed therein with a second reagent  328   a  and  328   b  located in a respective compartment  366  and  368 . The partition  364  is formed in such a manner so that the sample is split into the two compartments  366  and  368 . The second reagent is introduced to the mixture and is 12 allowed to react for a period of time. That is, the reagent and mixture combination is incubated for a period of time. 
     Next, the elongated holder member  348  containing the test strips  350   a  and  350   b  is inserted through the slit  346  and slid downwardly, toward the bottom  318  of the housing  312 . The test strips  350   a  and  350   b  are typical prior art test strips where various antigens are dried thereon that compete with the analyte being tested for a binding site on the antibody. The slit  346  is in fluid communication with the second chamber  326  so that the test strips  350   a  and  350   b  are forced into contact with the mixture and second reagent combination as it is pushed toward the bottom  318  of the housing  312 . Any reactions on the test strips  350   a  and  350   b  may be observed through the window  352 . 
     The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereto and accordingly, reference should be made to the appended claims rather than to the foregoing specification as indicating the scope of the invention.