Abstract:
An improved forensic specimen collector includes a collection matrix coated with a dissolvable coating composition. The coating composition covers the irregular surface of the matrix, filling in the holes and openings to prevent passage of collected material specimens into the interior of the matrix. This facilitates retention of the specimens on the outer surface of the matrix and release of all of the specimens for analysis. The specimens are separated from the surface of the collection matrix by contacting the matrix with a liquid solvent selected to dissolve the coating, thereby releasing the specimen into the solvent. The solvent is selected in accordance with its solubility characteristics to form either a suspension of the specimen in the solvent, or to dissolve the specimen into the solvent to form a solution.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]    This application claims priority under 35 U.S.C. 119(e) and 37 C.F.R. 1.78(a)(4) based upon copending U.S. Provisional Application Ser. No. 60/834,874 for COATED DISSOLVABLE SPECIMEN COLLECTION ABSORBENT, filed Aug. 2, 2006 which is expressly incorporated herein by reference. 
     
     BACKGROUND OF THE INVENTION  
       [0002]    The present invention is generally concerned with the collection and release of specimens and samples for subsequent analysis. More particularly, it is concerned with forensic specimen collection devices having coatings that promote more efficient collection of specimens of interest and that are dissolvable to permit delivery of all of the captured specimens for analysis without quantitative or qualitative impairment of the analysis. 
         [0003]    When a crime has been committed, collection and forensic analysis of evidence are often crucial to determination of guilt or innocence. Trace evidence may be used to associate victims and suspects with each other and with a crime scene. For example, DNA may be recovered from biological samples, such as body fluids, stains, fragments of tissue, bone or hair. Trace evidence may also include nonbiological materials such as residues from gunshots and explosives, unknown chemicals and pharmaceuticals, inks, paints, plastics, fibers, building materials, metals, glass, wood and soil. 
         [0004]    Trace evidence is commonly collected using a collector such as a swab having an elongate shaft with a collection tip at one end. The tip is generally covered with an absorbent collection matrix pad consisting of a cellulosic or synthetic resin material such as cotton, rayon or polyester. The material of the collection matrix may be fibrous, or it may be in the form of a net or sponge. While such swabs may appear to present a fairly smooth surface when viewed with the unaided eye, they are actually covered with surface irregularities such as openings, pores and holes which aid in the absorption of liquid specimens and enhance the ability of the swab to retain collected dry specimens. 
         [0005]    Depending on the specimen of interest, the swabs may be used in a dry condition to absorb liquids or solids suspended in liquids, or to capture dry particles, or they may be moistened with a suitable liquid to assist in dissolving dried or congealed liquid specimens or in capturing dry specimens. The swabs are swiped, rubbed or dabbed against the specimen of interest to capture or absorb the specimen for collection. Where the specimen is suspended in the air, swabs may be waved through the air to contact and capture the specimens or they may be placed in a selected location to collect particles that settle out of the air. The specimens may also be collected with the assistance of a vacuum device. Once collected, the specimens are retained on or within the collection matrix of the swabs, which are generally placed in individually labeled, airtight specimen containers such as bags or specimen boxes, until they can be transferred to a laboratory for analysis. 
         [0006]    In the laboratory, the captured specimens must be separated from the collection matrix for analysis. This may be accomplished by treating the specimen-containing portion of the swab with a solvent to dissolve or elute the specimens into solution with the solvent, which may then be stored in a container such as a flask or test tube awaiting analysis. Portions of the swab not containing specimens may be similarly treated to serve as a control. Where it is not desirable to dissolve the specimens, they may be washed from the swab using a liquid to form a suspension, or they may be physically removed, as by tapping or shaking of the swab or by using mechanical means such as forceps to grasp the specimens one-by-one and remove them or by cutting up the specimen. 
         [0007]    While the irregular surface of the swab collection matrix is extremely helpful in capturing and retaining the collected specimens, it may also serve to impair removal of specimens from the swab for the necessary analysis. Where the specimens are particulates which are not to be dissolved, such as skin flakes or hair fragments they may become entrapped within the interior of the collection matrix and become extremely difficult to remove. While some portion of the specimens may be physically removed and available for analysis, the quantity of specimen recovery may be substantially reduced. Accordingly, there is a need to modify the surface of the swabs using a known composition having properties that will not impair the ability of the swabs to collect and retain specimens of interest, and that can be easily removed from the collection matrix along with the specimens, without interfering with subsequent analysis of the specimens. 
       SUMMARY OF THE INVENTION  
       [0008]    The present invention provides a greatly improved specimen collector having a dissolvable surface coating. The specimen collector includes a collection matrix presenting an outer surface and an interior portion. The outer surface includes irregularities such as holes and openings into the interior portion. When material specimens are collected, some of the smaller specimens pass through the holes and openings into the interior of the matrix, where they become entrapped in the material of the matrix and are difficult to remove. The irregular surface of the collection matrix is modified by application of a dissolvable coating composition. 
         [0009]    The coating composition covers the irregular surface of the matrix, filling in the pours or holes and openings. This facilitates retention of the specimens on the outer surface of the matrix and prevents collected specimens from passing through the openings and into the interior portion of the matrix. The specimens may be separated from the surface of the collection matrix by contacting the coating of the matrix with a liquid solvent selected for its ability to dissolve the coating, as well as the specimen, and thereby release the specimen into the solvent or elution buffer. An elution buffer is a predetermined solution of selected compounds designed to provide an optimal environment for the analytes of interest prior to and during analysis. A typical elution buffer is a phosphate buffered solution used for biological samples. The solvent or elution buffer may be selected in accordance with its solubility characteristics to form either a suspension of the specimen in the solvent, or to dissolve the specimen into the solvent to form a solution. 
         [0010]    Various objects and advantages of this invention will become apparent from the following description taken in conjunction with the accompanying drawings wherein are set forth, by way of illustration and example, certain embodiments of this invention. 
         [0011]    The drawings, including  FIGS. 1-10 , constitute a part of this specification, include exemplary embodiments of the present invention, and illustrate various objects and features thereof. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0012]      FIG. 1  is a diagrammatic perspective view of a swab showing a prior art collection tip having no specimen collection matrix surface coating. 
           [0013]      FIG. 2  is a diagrammatic perspective view of a test tube containing a prior art swab as shown in  FIG. 1  showing specimens captured on the matrix surface. 
           [0014]      FIG. 3  is a diagrammatic perspective view showing the collection tip of the prior art swab of  FIG. 2  immersed in a solvent liquid, with part of the collected specimens dissolved in the solvent liquid and part of the collected specimens retained by the collection matrix surface. 
           [0015]      FIG. 4  is a diagrammatic perspective view of a swab showing a collection tip and specimen collection matrix having a surface coating. 
           [0016]      FIG. 5  is a diagrammatic perspective view of a test tube containing a swab as shown in  FIG. 4  showing specimens captured on the modified surface. 
           [0017]      FIG. 6  is a diagrammatic perspective view showing the collection tip of the swab of  FIG. 5  immersed in a solvent liquid, with the surface coating and collected specimens in the process of dissolving in the solvent liquid. 
           [0018]      FIG. 7  is a diagrammatic perspective view showing the tube of  FIG. 6  with the swab removed and the surface coating and specimen fully dissolved in the solvent. 
           [0019]      FIG. 8  is a diagrammatic perspective view of the swab shown in  FIG. 4  after the surface coating and specimens have been dissolved off. 
           [0020]      FIG. 9  is a greatly enlarged diagrammatic cross-section view taken along line  9 - 9  of  FIG. 8  of a collection matrix showing openings in the outer surface coated by a coating composition. 
           [0021]      FIG. 10  is a flow diagram showing the steps in a method of use of a coated specimen collector. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0022]    As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure. 
         [0023]      FIG. 1  shows a prior art collection device A comprising a shaft B having a collection matrix C mounted thereon. The collection matrix C is generally rough surfaced in nature and contains various interstitial areas D which can trap a specimen E collected thereon and inhibit elution or removal of the specimen E from the matrix C. Typically, as shown in  FIG. 2 , specimen collection device A will be inserted into a standard test tube F and an elution buffer or other solution G for dissolving or separating specimen E from collection matrix C is added to tube F. As shown in  FIG. 3 , such elution of a specimen E is only partially successful with some of specimen E being eluted or dissolved into solution such as shown in  FIG. 3  by eluted specimen H which is in solvent or elution buffer G and removed from matrix C. However, a certain amount of specimen E continues to be retained on matrix C as it is bound to collection matrix C by being trapped within interstitial spaces D of matrix C. The present invention, as described hereinafter, overcomes this debility of the prior art by avoiding entrapment of specimen particles within the interstitial spaces of a collection matrix. 
         [0024]    Referring now to drawing  FIGS. 4-9 , the reference numeral  1  refers to a coated specimen collector  1 , which is depicted in  FIGS. 4-6  in association with a quantity of material samples or specimens  2 . The collector  1  is depicted in the form of a swab, having an elongate shaft  3 , with a pair of ends. The shaft  3  may be constructed of wood, paper, resin, glass or metal, and it may be flat, tubular, cylindrical, tab-shaped or it may be of any other suitable material and configuration. 
         [0025]    One end of the shaft  3  is connected to a head or tip portion  5 . As shown in  FIGS. 4 and 5 , the tip  5  is covered with a collection matrix  6 . The collection matrix  6  is generally formed from an absorbent cellulosic or synthetic resinous material such as, for example, cotton, rayon or polyester. The matrix  6  may also be selected from any other suitable material that will not interfere with collection of a specimen of interest and retention of the collected specimen on the collector head  5 , that is compatible with the specimen of interest and the coating, and that will not interfere with release of the specimen or dissolution of the matrix coating. The material may be in the form of a fibrous wadding that is wrapped around the end of the shaft  3 , or it may be in the form of a small pad, sponge or net that is attached to the shaft  3 . An inert adhesive composition may also be employed to retain the material in place on the shaft  3 . It is foreseen that the collector  1  may be constructed without a shaft  3 , so that it consists of only the collection matrix  6  in the form of a ball, pad, wipe, stick or net. 
         [0026]    Regardless of the overall configuration of the collector  1 , the collection matrix  6  ( FIG. 9 ) presents an irregular outer surface  11  having a plurality of holes, pores or openings  12  in communication with an interior portion  13  of the matrix. The matrix  6  is generally covered with a quantity of a dissolvable coating composition  14 , ( FIG. 9 ) which blocks or fills some or all of the openings  12 , thereby preventing passage of at least some of the specimens  2  into the matrix interior  13 . 
         [0027]    The coating composition  14  is selected for solubility characteristics that enable it to dissolve in a preselected extraction or elution solvent. As used herein, the term “dissolve” means the chemical process of solvation (including hydration), in which a solute is dissolved in a solvent, creating a solution. The solute coating composition  14  herein is dissolved in an extraction or elution solvent to create a solution containing solubilized coating composition and solvent. The coating composition  14  and the solvent may be selected for solvation under ambient conditions. It is also foreseen that the coating composition and/or the solvent may be preselected for solvation under conditions that require the temperature and/or pressure to be manipulated, i.e., by raising and/or lowering in order to control the induction or rate of solvation. 
         [0028]    The coating composition  14  is also selected based on consideration of additional factors such as the composition of the collection matrix, the surface irregularities thereon, the specimen of interest  2  to be collected, the conditions under which the specimen is to be collected, and the potential interactions between such factors. Some exemplary coating compositions are proteins such as albumin, salt solutions, carboxymethyulcellulose, polysaccharides, glucose, phosphate buffer solution, gelatin and mixtures thereof. Where the coated specimen collector  1  may be used to collect cells, for example from the mouth of a live subject, the coating composition is selected from materials generally regarded as safe for human contact or ingestion. 
         [0029]    The concentration of the coating composition  14  is also preselected based on the foregoing considerations and the ability of the composition  14  to modify the outer surface  11  of the collection matrix  6  to promote more efficient collection of the analytes of interest, such as, for example, DNA or other trace evidence, and of the surface coating  14  to dissolve into solution with the solvent and bring along all of the captured specimens  2  into an elution vessel or container such as a test tube  15  ( FIGS. 5-7 ). 
         [0030]    A known quantity of the coating composition  14  may be applied to the irregular surface  11  of the collection matrix  6  by passive absorption in the form of a liquid, or deposition of a vapor or gas which is allowed to dry prior to use. The coating  14  may also be applied by electrochemical assisted deposition or any other suitable method. In certain embodiments, the coating  14  may be formulated to retain a tacky surface after drying to facilitate collection of specimens of interest  2 . It is also foreseen that the coating composition  14  may be applied to specimen collector heads  5  that are not porous or irregular, in order to facilitate release of captured specimens  2 . The quantity of coating composition  14  applied to the collection matrix  6  is known and may be varied in accordance with the concentration of the coating  14 , the composition of the collection matrix  6  and the solvent, the specimen  2  to be collected, or any combination of the foregoing. 
         [0031]    The solvent  16 , shown in  FIG. 6  dissolving the coating  14  to form a solution, is also selected for solubility characteristics that permit solvation of the coating composition  14  so that it will elute the coating from the collection matrix  6 . It may also be preselected to dissolve the specimens  2  as well. The solvent may be in the form of a liquid, or it may be in the form of a vapor or a gas. The solvent may be organic, such as an aqueous solvent, or it may be organic and it may be in the form of a solution or mixture of suitable solvent compositions. 
         [0032]    In the steps of a method of use ( FIG. 10 ), a first step  21  is providing a specimen collector  1 . In a next step  22 , a known quantity of a coating composition  14  is provided  22 . In a next step  23 , the head  5  of the specimen collector  1  is contacted with a quantity of a coating composition  14  in the form of a liquid, vapor or gas to cause the coating  14  to deposit itself on the outer surface  11  of the collection matrix  6  in covering relation to at least some of the irregularities or openings  12  in the matrix surface  11  ( FIGS. 8 and 9 ). As an example, if the specimen collector  1  comprises a cotton swab, the swab head  5  including the cotton collection matrix  6  may be coated with a gelatin solution, a solution of carboxymethylcellulose, a glucose solution, a phosphate buffer solution or a polysaccharide solution. In the next step  24 , the coating composition  14  is permitted to dry on the matrix outer surface  11  for a period of time. It is foreseen that the collector  1  may also be used in a wet or tacky condition. If the specimen collector  1  comprises a rayon swab, the swab head  5 , including the rayon collection matrix  6  may be coated with a gelatin solution, albumin solution or a carboxymethylcellulose solution compatible with the solvent  16 . 
         [0033]    In a next step  25 , the coated collector matrix  6  is next used to contact a specimen of interest  2 , which is collected and retained on the coated surface of the collector  1  ( FIG. 4 ). A quantity of a preselected solvent is next provided  31 . In the next step  32 , the coated collection matrix outer surface  11  and collected specimens  2  are contacted with a quantity of the selected solvent  16 . This may be accomplished by introducing the collector  1  with collected specimens  2  into a container or vessel  15  such as a test tube ( FIG. 5 ). A quantity of a solvent  16  may be present in the tube  15  when the collector  1  is introduced, or the solvent  16  may be added to the tube  15  subsequently. In the next step  33 , the solvent  16  is permitted to dissolve the coating  14  and thereby release the specimens  2  from the outer surface  11  of the collection matrix  6  and into the solvent  16  ( FIG. 6 ). The collector  1  is next removed  34  from the vessel  15  ( FIG. 7 ), leaving a solution formed by the coating composition  14  and the solvent  16 . The specimens  2  may be dissolved in the solvent solution as shown in  FIG. 4 , or they may be suspended in the solution in an undissolved state. The specimen collector  1  with its collection matrix  6  with coating composition  14  and specimens  2  now fully eluted ( FIG. 7 ) may be discarded  34  or retained  35 . In the next step  41 , an analytical procedure is performed on the released specimens  2 . This step may be repeated using different reagents and procedures until the specimens  2  have been identified and characterized to the fullest possible extent. 
         [0034]    It is to be understood that while certain forms of the present invention have been illustrated and described herein, it is not to be limited to the specific forms or arrangement of parts described and shown.