Abstract:
Methods and systems for detecting chemical and biological agents using oligonucleotide aptamers. A sensor includes a detection aptamer that has a binding domain for the chemical or biological agent, and is bound to fibers of a textile such as a patch or article of clothing. The detection aptamer can be stabilized and enhanced through a stabilization agent such as trehalose or through binding to a nanoparticle which is then bound to the fiber. Binding of the chemical and biological agent of interest to the detection aptamer can be reported to the user or wearer of the textile in a variety of ways, including visually and electrically.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to detection of chemical and biological agents and, more specifically, to detection of chemical and biological agents using textile-based sensors. 
         [0003]    2. Description of the Related Art 
         [0004]    There is an increasing demand for assays for the detection and quantitative identification of chemical and biological hazards across a broad range of disciplines, including food safety, homeland security, and medical diagnostics. While there is existing technology for the detection and quantitative identification of chemical and biological hazards, these sensors are generally large, bulky, and/or slow sensor systems that require considerable time and effort to utilize or to move from one location to another. Accordingly, there is a continued need for fast, efficient, and portable sensor systems for chemical and biological hazard detection. 
         [0005]    Aptamers are single-stranded oligonucleic acid or peptide molecules that bind to a specific target molecule. The target molecule can be, for example, a protein, nucleic acid, cell, or tissue, among many others. While some aptamers are naturally occurring, most are designed for a specific target. Due to the high affinity and specificity for their target(s) of interest, aptamers are increasingly used as diagnostic reagents. Accordingly, aptamers are a potential component of sensors for the detection and quantitative identification of chemical and biological hazards. 
       BRIEF SUMMARY OF THE INVENTION 
       [0006]    It is therefore a principal object and advantage of the present invention to provide a method, device, and/or system for the detection of chemical and biological hazards. 
         [0007]    It is another object and advantage of the present invention to provide a method, device, and/or system that utilizes aptamer technology to detect chemical and biological hazards. 
         [0008]    It is yet another object and advantage of the present invention to provide a wearable, aptamer-based sensor for the detection of chemical and biological hazards. 
         [0009]    Other objects and advantages of the present invention will in part be obvious, and in part appear hereinafter. 
         [0010]    Embodiments include systems and methods for detecting chemical and biological agents using oligonucleotide aptamers. A textile-based sensor for detecting the presence of a biological or chemical target comprises: (i) a plurality of textile fibers; and (ii) a plurality of aptamer molecules each comprising a target binding domain and immobilized to the plurality of textile fibers, wherein, in the presence of the target, the target binds to the target binding domain of one or more of the plurality of aptamer molecules and a reporter signal is generated by the sensor. The sensor can further comprise a stabilizing agent such a trehalose, and a first and/or second plurality of nanoparticles for stabilization and/or detection. 
         [0011]    A further embodiment comprises a textile-based sensor for detecting the presence of a biological or chemical target comprising: (i) a plurality of textile fibers; (ii) a plurality of aptamer molecules, each comprising a target binding domain, immobilized to the plurality of textile fibers; (iii) a plurality of nanoparticles immobilized to a terminal end of the aptamer molecules; and (iv) a stabilizing agent adapted to stabilize the plurality of aptamer molecules; wherein, in the presence of the target, the target binds to the target binding domain of one or more of the plurality of aptamer molecules and one or more of the plurality of nanoparticles are released. 
         [0012]    Another embodiment comprises a textile-based sensor for detecting the presence of a biological or chemical target comprising: (i) a plurality of textile fibers; (ii) a plurality of metal nanoparticles immobilized to the plurality of textile fibers; (iii) a plurality of aptamer molecules, each comprising a target binding domain, immobilized to the plurality of metal nanoparticles; (iv) a plurality of insulating nanoparticles immobilized to a terminal end of the aptamer molecules; and (v) a stabilizing agent adapted to stabilize the plurality of aptamer molecules, wherein, in the presence of the target, the target binds to the target binding domain of one or more of the plurality of aptamer molecules and one or more of the plurality of insulating nanoparticles are released, resulting in a change in an electrical characteristic of the sensor. 
         [0013]    A further embodiment comprises a method for detecting the presence of a biological or chemical target using a textile-based sensor. According to one embodiment the method comprising the steps of: (i) contacting a sample with a sensor comprising a plurality of textile fibers and a plurality of aptamer molecules, each comprising a target binding domain, immobilized to the plurality of textile fibers, wherein in the presence of the target, said target binds to the target binding domain of one or more of the plurality of aptamer molecules; and (ii) detecting a reporter signal generated by the sensor in response to the target binding to the target binding domain of one or more of the plurality of aptamer molecules. The sensor can further comprise a stabilizing agent such a trehalose, and a first and/or second plurality of nanoparticles for stabilization and/or detection. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S) 
         [0014]    The present invention will be more fully understood and appreciated by reading the following Detailed Description in conjunction with the accompanying drawings, in which: 
           [0015]      FIG. 1  is a flowchart of an exemplary process for detecting the presence of a chemical or biological agent using an aptamer in accordance with an embodiment of the present invention; 
           [0016]      FIG. 2  is a schematic representation of a system for detecting the presence of a chemical or biological agent using an aptamer in accordance with an embodiment of the present invention; 
           [0017]      FIG. 3  is a schematic representation of a system for binding an aptamer to a textile in accordance with an embodiment of the present invention; 
           [0018]      FIG. 4  is a schematic representation of a system for detecting the presence of a chemical or biological agent using an aptamer in accordance with an embodiment of the present invention; and 
           [0019]      FIG. 5  is a schematic representation of a system for detecting the presence of a chemical or biological agent using an aptamer in accordance with an embodiment of the present invention; 
           [0020]      FIG. 6  is a schematic representation of an array for detecting the presence of a chemical or biological agent using an aptamer in accordance with an embodiment of the present invention; 
           [0021]      FIG. 7  is a schematic representation of an array for detecting the presence of a chemical or biological agent using an aptamer in accordance with an embodiment of the present invention; 
           [0022]      FIG. 8  is a schematic representation of an array for detecting the presence of a chemical or biological agent using an aptamer in accordance with an embodiment of the present invention; and 
           [0023]      FIG. 9  is a schematic representation of an array for detecting the presence of a chemical or biological agent using an aptamer in accordance with an embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0024]    Referring now to the drawings wherein like reference numerals designate identical or corresponding parts or steps throughout the several views, there is shown in  FIG. 1  a flowchart of an exemplary process for detecting the presence of a chemical or biological agent using aptamers. As an initial step  100 , an aptamer with high specific affinity for a chemical or biological agent of interest is isolated, identified, or created. Examples of biological agents of interest which can be used as a biological weapon include numerous bacterium, virus, prion, and fungus varieties, as well as biological toxins, cells, or tissues. Examples of chemical agents of interest include mustard gas, chloride gas, and sarin, among many other examples. Some of the prime targets for detection by the present system include microorganisms such as  Bacillus anthracis , members of the genii  Burkholderia, Rickettsia, Shingella, Vibrio , and  Yersinia pestis , viruses such as the smallpox virus, and toxic proteins such as ricin (from  Ricinus communis ) and botulinum toxin (from  Clostridum botulinum ), among many other agents. 
         [0025]    The aptamer can be any nucleic acid or peptide suitable of binding to a chemical or biological agent targeted by the system. Aptamers comprising nucleic acid, typically DNA or RNA, usually consist of a short oligonucleotide polymer, while peptide aptamers usually consist of a short peptide domain and are often attached to a protein scaffold. 
         [0026]    The aptamer can be created using any of a number of known methods in the art for isolating, identifying, or creating aptamers. While some aptamers are known to occur in nature, there are multiple methods used to selectively identify and create aptamers with high specific affinity for a target ligand such as a chemical or biological agent. The SELEX (systematic evolution of ligands by exponential enrichment) method, for example, uses multiple rounds of in vitro selection to selective—and then selectively evolve—a suitable aptamer from a large library of randomly generated oligonucleotide sequences. 
         [0027]    At step  110  of the method depicted in  FIG. 1 , the anti-biological or chemical agent aptamer is incorporated into a textile carrier for deployment within an environment where the biological or chemical target may be present. In a preferred embodiment, the anti-biological or chemical agent aptamer is covalently attached to a portion of the textile carrier. The term “textile” as used herein refers to any fiber, filament, or other structural component of fabric, cloth, or clothing worn or carried by an individual. 
         [0028]      FIG. 2  depicts a system  200  comprising a textile fiber  210 , which can be a natural fiber, a synthetic fiber, or a combination of the two, and a plurality of aptamers  220  which are bound to the fiber, optionally through use of a linker  230  which can be a portion of the aptamer or a component of the system other than the aptamer. Examples of natural fibers include cotton, wool, silk, and linen, among others. Examples of synthetic fibers include nylon, polyester, polyethylene, polypropylene, vinyl, rayon, and a wide variety of other synthetic fibers. 
         [0029]    The aptamer can be attached to textile fiber  210  through a variety of mechanisms. One such mechanism is thiolation as shown in  FIG. 3 ; the fiber and the aptamers can be thiolated using one of a number of chemical processes known in the art, and the thiolated apaters can be attached directly to the cotton through the thiol groups. Similarly the primary alcohol can be converted to a carboxy group through potassium permanganate when could then be used to add aminated oligonucleotides through EDC-NHS chemistry. Other mechanisms of attaching the aptamer to the textile fiber are possible. 
         [0030]    It may also be beneficial to stabilize the aptamers and/or the fibers to promote a more stable system  400 , and to enable the aptamers to function when out of solution. For example, system  400  could be stabilized with trehalose molecules  410 , a naturally-occurring disaccharide formed from two α-glucose units. As another example, the system could be stabilized with a hydrogel or other polymer (natural or synthetic). 
         [0031]    The aptamers could be further stabilized through use of nanoparticles, as shown in system  500  in  FIG. 4 . The aptamers  220  are bound to the nanoparticle  510  using one of a number of chemical processes known in the art. Nanoparticles  510  can be formed from any suitable molecules, including but not limited to metals such as gold, silver, and platinum, and plastics. The nanoparticles can be bound to the textile fiber  210 , and can be optionally combined with the stabilizer, such as trehalose molecules  410 . Alternatively, nanoparticles could be deposited onto the textile fiber then the aptamers could be sandwiched between the first nanoparticle and a second, colored, nanoparticle. 
         [0032]    At step  120  of the method depicted in  FIG. 1 , the textile comprising the anti-biological or chemical agent aptamer is exposed to an environment potentially comprising the target agent. For example, the textile can be clothing as small as a patch or button to as large as a full suit worn by anyone who might be exposed to harmful agents. This could include military personnel, emergency responders, haz-mat teams, firemen, policemen, and a wide variety of other individuals. At step  130  of the method the target agent binds to the aptamer. 
         [0033]    At steps  140  and  150  of the method depicted in  FIG. 1 , the system detects and then reports the presence of the target agent. Accordingly, the textile/aptamer system also comprises a mechanism for notifying a user if a target chemical or biological agent is detected (i.e, bound by the aptamer). For example, the system can include a nanoparticle  610  bound to a terminal end of the aptamer  220 , as shown in system  600  in  FIG. 6 , using any one of a number of chemical processes known in the art. Further, system  600  can be combined with any of the other elements described herein, including a stabilizer such as trehalose and a nanoparticle to bind the aptamer to the textile. According to one embodiment, nanoparticle  610  is a colored nanoparticle. There are a number of colored nanoparticles known in the art, including but not limited to nanoparticles used for electronic inks. 
         [0034]    In yet another embodiment, a porous nanoparticles could also be used where the target chemical or biological agent must diffuse into the nanoparticle for the cleavage reaction to occur, again changing the color of the fiber and releasing a second colored nanoparticle attached through the oligonucleotide. 
         [0035]    For detection of the target chemical or biological agent  710 , nanoparticle  610  would be released from the system as shown in  FIG. 7 , including being released from aptamer  220  as a consequence of target binding to the aptamer, or the terminal portion of aptamer  220  being cleaved from the system by binding of the target. This would result in a color change to the system. As perceived by the wearer or user, the textile would appear to change color in the presence of the target chemical or biological agent  710 . In an alternative embodiment, detection mechanism  610  is a dye or color imparting agent that is activated, including by adding or imparting color to the textile fiber itself, upon release from the aptamer. For example, the dye or color imparting agent may react with the textile or components embedded within the textile to yield a color only when the agent is released from the aptamer or the system via binding of the chemical or biological agent of interest. In yet another embodiment, the detection mechanism  610  is a color quencher that quenches a color upon binding of the chemical or biological agent of interest. For example, the color quencher may react with the textile or components embedded within the textile to quench a color only when the agent is released from the aptamer or the system via binding of the chemical or biological agent of interest. 
         [0036]    Detection could also be achieved electrically, as shown in system  800  in  FIG. 8 . Nanoparticle  510  is a conductive metal nanoparticle such as gold, silver, platinum, or any one of a wide variety of conductive nanoparticles, and is attached to the textile fiber  210  using any one of a number of chemical processes known in the art. An insulating nanoparticle  810  is attached to the terminal end of aptamer  220  using any one of a number of chemical processes known in the art, increasing the resistance of the system. Upon binding of the chemical or biological target of interest  710 , as shown in  FIG. 9 , insulating nanoparticle  810  leaves the system and the resistance of the overall system decreases, which could be measured by a monitoring circuit. When that decrease in resistance is detected by the monitoring circuit, a signal could be given to the user directly or could be sent wirelessly to a different location. System  800  could further be combined with any of the other elements described herein, including a stabilizer such as trehalose and a nanoparticle to bind the aptamer to the textile. 
         [0037]    Although the present invention has been described in connection with a preferred embodiment, it should be understood that modifications, alterations, and additions can be made to the invention without departing from the scope of the invention as defined by the claims.