Patent Abstract:
The present invention relates to solid supports that are used for the storage and further processing of biological materials. The invention is particularly concerned with solid supports which have at least one surface coated with a chemical mixture that enhances the recovery of the biological material from the support. Methods of preparing and using the solid supports are also described.

Full Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to solid supports and is particularly concerned with solid supports which can be used in the storage, recovery and further processing of biological materials such as biopharmaceutical drugs. 
       BACKGROUND TO THE INVENTION 
       [0002]    The use of solid supports such as filter paper for the collection and analysis of human blood dates back to the early 1960s, when Dr. Robert Guthrie used dried blood spot (DBS) specimens to measure phenylalanine in newborns for the detection of phenylketonuria (Mei, J., et al., 2001; Journal of Nutrition, 131:1631S-1636S). This novel application for collecting blood led to the population screening of newborns for the detection of treatable, inherited metabolic diseases. DBS have now been used for over 40 years to screen for a large range of neonatal metabolic disorders. 
         [0003]    DBS specimens are collected by spotting whole blood onto a solid support, such as a membrane, glass fiber or paper, either from venous blood or directly from a finger or heel prick, making this method particularly suitable for the shipment of specimens from peripheral clinics to central laboratories. Furthermore, DBS packed in zip-lock plastic bags with desiccant can be stored and shipped at ambient temperature, thus avoiding the need for i) cold chain storage and ii) fast specialized transportation. DBS collected by applying a drop of blood onto an absorbent material such as Whatman 903 Neonatal STD paper are not subject to the IATA Dangerous Goods Regulations (Addendum II, March 2005). 
         [0004]    Additional solid paper supports that are used for collecting, transportation and storing DBS and other bodily fluids for newborn and neonatal screening purposes include— 
       1. Ahlstrom 226 
       [0005]    2. Munktell TFN(CE marked)
 
3. Toyo Roshi grade 545 Advantec Toyo, Tokyo (see Elvers L et al 2007; J. Inherit Medtab Dis 30, 4, 609).
 
         [0006]    All of these papers like the Whatman 903 Neonatal STD paper consist of cotton linters. The Whatman 903 Neonatal STD and Ahlstrom 226 papers are classified as Class II Medical devices. Solid paper supports that have the potential to be developed into devices for newborn and neonatal screening purposes include those manufactured by Macherey Nagel (e.g. MN818), Reeve Angel (e.g. Double ring) and Hahnemuhle Grade 2292. 
         [0007]    The consumable costs for DBS are less than US$1 per test, and transport costs are markedly reduced compared with plasma, which requires a liquid format and specialized transportation conditions (Johannessen, A., et al., 2009; J Antimicrobial Chemotherapy, 64, 1126-1129). Although the actual assay costs remain unchanged, and the extraction of analytes from DBS involves some extra hands-on time at a centralised laboratory, the use of DBS and specifically solid paper supports is increasingly used in the storage and/or analysis of biological materials such as nucleic acids, proteins etc. In addition, DBS have also been utilised during the drug discovery process in which candidate low molecular weight drug compounds have been introduced into test animals and concentration levels in the blood monitored. 
         [0008]    In recent years, biotechnologically-derived recombinant proteins, peptides and antibody-based drugs, as well as antisense oligonucleotides and DNA for gene therapy, have developed into mainstream therapeutic agents and now constitute a substantial portion of the compounds under clinical development. These agents are commonly termed “biotech-drugs” or “biopharmaceutical drugs” to differentiate them from low molecular weight drug compounds. 
         [0009]    Drug Metabolism and Pharmacokinetic (DMPK) analysis of Biotech-drugs and low molecular weight drug compounds is important as DMPK analysis is vital to drug discovery as it provides insight into how drug candidates may be absorbed, metabolised and excreted by the body. Analyses are routinely performed at the drug discovery stage and involve dosing animals with the compound of interest, and measuring the drug (or metabolite) concentration in biological fluids as a function of time. This generates valuable information such as drug clearance, bioavailability etc, but demands a significant amount of time and resource (Beaudette, P., et al., 2004; J. of Chromatography B 809, 153-158). 
         [0010]    Major problems associated with the DMPK analysis, typically conducted in drug screening programmes, are the apparent lack of a suitable storage media for maintaining stability and integrity in blood samples prior to analysis. Current methodologies use plasma or whole blood collected from the dosed animals at designated times. However, this method has a number of drawbacks including the involvement of time-consuming procedures which create a bottleneck in the analysis process. In addition, the multiple bleeding of individual animals for time-course experiments is restrictive. This puts a limitation on throughput and increases the use of animals, which has the result that fewer lead compounds can be advanced. 
         [0011]    The small blood volume needed for DBS enables serial blood sampling from one animal rather than composite bleeds from several animals which significantly improves the quality of DMPK and toxicokinetic data and assessments. The ethical benefits of the reduced blood volume (typically 15-20 μl per spot) needed for DBS with regard to the “3Rs” (reduction, refinement, and replacement) are obvious in preclinical drug development. The numbers of test animals can be significantly reduced. In addition, non-terminal blood sampling is possible in juvenile toxicity studies which are increasingly required by authorities as part of the safety evaluation of drugs for paediatric use. Another advantage for regulatory animal toxicology studies is the increase in data quality. 
         [0012]    Therefore due to the growing need for rapid analysis of large quantities of blood samples in pharmacokinetic research, DBS have become an attractive option. For paper to perform as a solid support for DBS it is desirable that the paper combines satisfactory mechanical properties with an ability to hold the biological material of interest in a stable condition in such a way that it can be subjected to further processing and/or analysis post-storage. Examples of such papers used for DMPK analyses are those known as 903 Neonatal specimen collection papers and also papers known as FTA and FTA Elute described, for example, in U.S. Pat. Nos. 5,75,126 and 5,939,259. 
         [0013]    Additional solid paper supports used for DMPK analyses include the following— 
         [0000]    1. Ahlstrom grade 226 paper:
 
Use of Dried Plasma Spots in the Determination of Pharmacokinetics in Clinical Studies: Validation of a Quantitative Bioanalytical Method. Barfield, M., et al., (2011), Anal., Chem., 83, 118-124.
 
2. Standardized Filter paper:
 
Drug monitoring of lamotrigine and oxcarbazepine combination during pregnancy Wegner, I., et al., (2010), Epilepsia, 51, 2500-2502.
 
3. Whatman 903, FTA (DMPK-A) and FTA Elute (DMPK-B) substrates:
 
Effect of storage conditions on the weight and appearance of dried blood spot samples on various cellulose-based substrates.
 
       Denniff, P., et al., (2010), Bioanalysis, 2, 11, 1817-22. 
     4. Whatman DMPK-A, -B, -C: 
       [0014]    Application of DBS for quantitative assessment of the peptide Exendin-4; comparison of plasma and DBS method by UHPLC-MS/MS. 
       Kehler, R., et al., (2010), Bioanalysis, 2, 8, 1461-1468. 
       [0015]    5. Ahlstrom grade 237 paper: 
       Application of a Liquid Extraction Based Sealing Surface Sampling Probe for Mass Spectrometric Analysis of DBS &amp; Mouse Whole-Body Thin Tissue Sections Van Berkel, G., et al., (2009), Anal., Chem., 2009, 81, 21, 9146-9152. 
       [0016]    6. Whatman FTA blood spot cards:
 
Dried blood spots as a sample collection technique for the determination of pharmacokinetics in clinical studies: considerations for the validation of a quantitative bioanalytical method.
 
       Spooner, N., et al., (2009), Anal Chem. 81, 1557-63. 
       [0017]    7. Whatman FTA Elute Micro card:
 
Study of dried blood spots technique for the determination of dextromethorphan and its metabolite dextrorphan in human whole blood by LC-MS/MS.
 
Liang, X., et al., (2009), J. Chrom B, Anal. Tech Biomed &amp; Life Sci, 877, 799-806.
 
8. Whatman filter paper cards:
 
A liquid chromatography/Tandem mass spectrometry method for determination of 25-hydroxy vitamin D2 and 25-hydroxy vitamin D3 in dried blood spots: a potential adjunct to diabetes and cardiometabolic risk screening.
 
       Newman, M., et al., (2009), J Diabetes Sci and Tech. 3, 156-162. 
       [0018]    9. Toyo Roshi No. 545 filter paper (Advantec Toyo, Tokyo): Simultaneous determination of 17α-hydroxypregnenolone and 17α-hydroxyprogesterone in DBS from low birth weight infants using LC-MS/MS. Higashi, T., et al., (2008), J. Pharm and Biomedical Analysis, 48, 1, 177-182.
 
10. Whatman specimen collection paper BFC 180:
 
Determination of morphine &amp; 6-acetylmorphine in blood with use of dried blood spots.
 
       Garcia-Boy, R., et al., (2008), Therapeutic Drug Monitoring, 30, 6, 733-739. 
       [0019]    11. Whatman filter paper (catalog no. 10535097):
 
Quantification of cationic anti-malaria agent methylene blue in different human biological matrices using cation exchange chromatography coupled to tandem mass spectrometry.
 
Burhenne, J., et al., (2008), J. Chrom B, Anal. Tech Biomed &amp; Life Sci, 863, 273-282.
 
       12. Whatman 3MM: 
       [0020]    Use of filter paper for sample collection and transport in steroid pharmacology. Howe, C., et al., (1997), Clin Chem. 43, 1408-15. 
       13. Whatman FTA, FTA Elute, DMPK-A, B, C, Ahlstrom 226— 
       [0021]    Determination of Tamiflu® and active metabolite in dried blood spots using the SCAPTM DBS system and column-switching LC-MS/MS. 
       Heinig, K., et al., F. Hoffmann-La Roche, Basel, Switzerland. 
       [0022]    (see: http://www.presearch.co.uk/pages/products/applications/1725/Determination%20of%20Tamifiu%C2%AE%20and%20active%20metabolite%20in%20dried%20blood%20spots%20using%20the%20SCAPTM%20DBS%20system.pdf) 
         [0023]    Solid paper supports that have the potential to be developed into devices for DMPK purposes include Munktell TFN grade, Toyo Roshi grade 545, Macherey Nagel (e.g. MN818), Reeve Angel (e.g. Double ring) and Hahnemuhle Grade 2292). 
         [0024]    For effective downstream processing and analysis, the analyte of interest (such as endogenous proteins or Biotech drugs) must be easy to extract from the solid paper support using relatively simple techniques that are amenable to high throughput. 
         [0025]    The combination of DBS and the detection of endogenous protein has been described in the scientific literature. For example, the biomarker for cystic fibrosis (CF) immunoreactive trypsin (IT), the first reported use of endogenous IT from DBS for CF screening was published by Ryley et al., in 1981 (J. Clin. Pathol. 34, 906-910). Since then, IT has been routinely used as an indicator of CF using DBS from neonates. A number of commercial organisations supply FDA approved immunoassay kits for this application. Many simply use a “paper-in” approach, in which a paper punch containing the DBS is applied directly in to the immunoassay and the analyte of interest is extracted in situ. Recently (Lindau-Shepard &amp; Pass, 2010, Clinical Chem. 56, 445-450) demonstrated that IT exists in two different isoforms. These authors reported the development of a suspension (or paper-in) array-based immunoassay for the diagnosis of CF using the two different isoforms of IT. All these protein-based studies were carried out on uncoated Guthrie cards (Whatman 903 paper). 
         [0026]    Since the inception of anonymous human immuno-deficiency (HIV) screening, over 1.2 million DBS tests have been carried out for the serological detection of endogenous anti-HIV antibodies in the blood from expectant mothers. 
         [0027]    These studies have proved that i) concerns about long-term storage of blood and any associated proteins of interest have proved unfounded and ii) the presence of haem in the DBS does not interfere with assay performance. 
         [0028]    It is therefore desirable to produce solid supports which provide a simple, stable storage medium for biological materials, including i) endogenous moieties and ii) biopharmaceutical or biotech drugs, which give a high yield or recovery of the biological material on further processing. The present invention addresses these needs and provides methods that enhance the recovery levels of biological materials such as biopharmaceutical drugs from biological samples stored as DBS on solid supports, particularly solid paper supports. 
       DEFINITIONS 
       [0029]    The term “biological material” as used herein shall mean any “biomolecule”, “synthetically-derived biomolecule”, “biopharmaceutical drug” or “cellular component” as defined below: 
         [0000]    i) A biomolecule is any organic molecule that is produced by a living organism, including large polymeric molecules such as proteins, polysaccharides, and nucleic acids as well as small low molecular weight molecules such as primary metabolites, secondary metabolites, and natural products.
 
ii) A synthetically-derived biomolecule, is a “biomolecule” as defined in i) above that is generated using recombinant DNA technologies or chemically synthesised by other non-living in-vitro methods.
 
iii) A biopharmaceutical drug (or “biotech drug”) is a biotechnologically-derived recombinant protein, peptide or antibody-based drug, or an antisense oligonucleotide, protein nucleic acid (PNA) or deoxy ribonucleic acid (DNA) for gene therapy.
 
iv) A cellular component is a unique, highly organized substance or substances of which cells, and thus living organisms, are composed. Examples include membranes, organelles, proteins, and nucleic acids. Whilst the majority of cellular components are located within the cell itself, some may exist in extracellular areas of an organism.
 
       SUMMARY OF THE INVENTION 
       [0030]    According to a first aspect of the present invention, there is provided a solid support having at least one surface coated with a chemical mixture that enhances the recovery of a biological material from the surface, wherein the chemical mixture is a mixture selected from the group consisting of vinyl polymer and non-ionic detergent, vinyl polymer and protein, non-ionic synthetic polymer and non-ionic detergent, non-ionic synthetic polymer and protein, polyethylenemine (PEI) and non-ionic detergent, non-ionic detergent and protein, and polyethylenemine (PEI) and protein. 
         [0031]    In one aspect, the solid support is selected from the group consisting of paper, glass microfiber and membrane. 
         [0032]    Preferably the support is a paper, more preferably a cellulose paper. 
         [0033]    In a further aspect, the solid support is a membrane selected from the group consisting of polyester, polyether sulfone (PES), polyamide (Nylon), polypropylene, polytetrafluoroethylene (PTFE), polycarbonate, cellulose nitrate, cellulose acetate and aluminium oxide. 
         [0034]    In another aspect, the vinyl polymer is polyvinyl pyrrolidone (PVP). 
         [0035]    In a further aspect, the non-ionic detergent is Tween 20. 
         [0036]    In a further aspect, the protein is albumin. 
         [0037]    In one aspect, the non-ionic synthetic polymer is poly-2-ethyl-2-oxazoline (PEOX). 
         [0038]    In another aspect, the chemical mixture is polyvinyl pyrrolidone (PVP) and Tween 20. 
         [0039]    In a further aspect, the chemical mixture is polyvinyl pyrrolidone (PVP) and albumin. 
         [0040]    In one aspect, the chemical mixture is chemical mixture is Tween 20 and albumin. 
         [0041]    In another aspect, the chemical mixture is poly-2-ethyl-2-oxazoline (PEOX) and Tween 20. 
         [0042]    In a further aspect, the chemical mixture is poly-2-ethyl-2-oxazoline PEOX and albumin. 
         [0043]    In one aspect, the chemical mixture is polyethylenemine (PEI) and Tween 20. 
         [0044]    In another aspect, the chemical mixture is polyethylenemine (PEI) and albumin. 
         [0045]    In a further aspect, the support is a paper, for example a cellulose paper. Examples of a cellulose paper include a 903 Neonatal STD card. 
         [0046]    According to a second aspect of the present invention, there is provided a method of recovering a biological material from a solid support comprising the steps of
       i) contacting a surface of a solid support as hereinbefore described with a sample containing a biological material;   ii) drying the sample on the surface of the solid support;   iii) storing the solid support; and   iv) extracting the biological material from the surface.       
 
         [0051]    In one aspect, step iii) comprises storing the paper support at a temperature in the range of 15 to 40° C. Preferably, the temperature is in the range of 20 to 30° C. In another aspect, the paper support is stored at a lower temperature depending on the thermal stability of the biological material. 
         [0052]    The nature of the sample will depend upon the source of the biological material. For example, the source may be from a range of biological organisms including, but not limited to, virus, bacterium, plant and animal. Preferably, the source will be a mammalian or a human subject. For mammalian and human sources, the sample may be selected from the group consisting of tissue, cell, blood, plasma, saliva and urine. 
         [0053]    In another aspect, the biological material is selected from the group consisting of biomolecule, synthetically-derived biomolecule, cellular component and biopharmaceutical drug. 
         [0054]    According to a third aspect of the present invention, there is provided a method of making a solid support as hereinbefore described, comprising coating at least one surface of the support with a solution of a chemical mixture that enhances the recovery of a biological material from the surface, wherein the chemical mixture is a mixture selected from the group consisting of polyvinyl pyrrolidone (PVP) and Tween 20, polyvinyl pyrrolidone (PVP) and albumin, Tween 20 and albumin, poly-2-ethyl-2-oxazoline (PEOX) and Tween 20, poly-2-ethyl-2-oxazoline PEOX and albumin, polyethylenemine (PEI) and Tween 20, and polyethylenemine (PEI) and albumin. 
         [0055]    In one aspect, the solid support is a paper, preferably a cellulose paper such as 903 Neonatal STD paper. 
         [0056]    According to a third aspect of the present invention, there is provided a use of a solid support as hereinbefore described for enhancing the recovery of a biological material from a surface thereof. 
         [0057]    In one aspect, the biological material is a biopharmaceutical drug. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0058]      FIG. 1  presents the recovery of exogenously-added IL-2 from dried blood spots applied to various paper matrices. 
           [0059]      FIG. 2  presents the recovery of exogenously-added IL-2 from dried blood spots applied to 903 Neonatal STD papers coated with various chemicals. 
           [0060]      FIG. 3  presents the recovery of exogenously-added IL-2 from dried blood spots applied to 903 Neonatal STD papers coated with paired combinations of chemicals. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0061]    Recombinant IL-2±carrier (R &amp; D Systems; Cat. 202-IL-CF-10 μg; lot AE4309112 and Cat. 202-IL-10 μg; lot AE4309081 respectively) was dissolved in either Dulbecco&#39;s PBS without calcium and magnesium (PAA; Cat. H15-002, lot H00208-0673), EDTA-anti-coagulated human, rabbit or horse blood (TCS Biosciences) at 50 μg or 100 μg/μl. 
         [0062]    Aliquots (1 μl containing 0, 50 or 100 μg of IL-2) were applied to the following GE Healthcare filter papers; 903 Neonatal STD card, Cat. 10538069, lot 6833909 WO82; DMPK-A card, Cat. WB129241, lot FT6847509; DMPK-B card, Cat. WB129242, Lot FE6847609 and DMPK-C card, Cat. WB129243, Lot FE6847009. Samples were allowed to dry overnight at ambient temperature and humidity. 
         [0063]    Punches (3 mm diameter) were extracted from each paper type using the appropriately sized Harris Uni-core punch (Sigma, Cat.Z708860-25ea, lot 3110). Single punches were placed into individual wells of the IL-2 microplate derived from the Human IL-2 Quantikine ELISA (R &amp; D Systems, Cat. D0250, lot 273275). These plates are coated with a mouse monoclonal antibody against IL-2. The IL-2 protein was eluted from the paper punch using the assay buffer (100 μl) supplied with the Quantikine kit. All subsequent steps were performed according to the instructions supplied with the Quantikine kit using a “paper in” method (paper punches are placed directly into the assay buffer and the analyte eluted directly in situ). On completion of the assay the optical density of the microplate was monitored at 450 nm using a Thermo Electron Corporation, Multiskan Ascent. The recovery of IL-2 was determined by comparing values to a standard curve of known IL-2 concentrations. A fresh IL-2 standard curve was prepared for each individual experiment. 
         [0064]    Additional experiments involved the addition of IL-2-spiked blood to 903 Neonatal STD cards after the cards had been saturation dipped in several chemical solutions (as described below). In certain instances the paper was also saturation dipped in a mixed solution containing several of these chemicals to determine if the chemicals exhibited any additive or synergistic effect on the recovery of IL-2 from the dried blood spots. 
       Chemicals Used 
       [0065]    A list of the chemicals and their sources is given below. 
         [0000]    Poly-vinyl-alcohol (Sigma; Cat. P8136, lot 039k0147).
 
Poly-ethyl-enemine, 50% in water (Fluka; Cat. P3143, lot 29k1492).
 
Poly-vinyl-pyrolodine, 1% in water (Sigma; Cat.PVP40-100 mg, lot 11 pk0097).
 
Inulin, 1% in water (Sigma; Cat. 12255-100 g, lot 079F7110).
 
Poly-2-ethyl-2-oxazoline, 1% in water (Aldrich Cat. 372846, lot 30498PJ).
 
Tween 20, 1% in water (Sigma, Cat. P7949-100 ml, lot. 109k01021).
 
α-β-Trehalose, 10 mg/ml (Sigma, Cat. T0299-50 mg, lot 128k1337).
 
Albumin, 1% in water (Sigma, Cat A2153-10 g, lot 049k1586).
 
Caesin from bovine milk, 1% in water (Sigma, Cat. C5890-500 g, lot 089k0179).
 
Poly-ethylene glycol 1000, 1% in water (Biochemika, Cat. 81189, lot 1198969).
 
Poly-ethylene glycol 200, 1% in water (Fluka, Cat. 81150, lot 1384550).
 
       Experimental Results 
       [0066]    When IL-2 was dissolved in EDTA-anti-coagulated blood, the 903 and DMPK-C cards facilitated the recovery of 45-55% of the cytokine, while only 2-3% was recovered from the DMPK-A and B cards (see Table 1 and  FIG. 1 ). The 903 and DMPK-C cards are the basic base papers and have not been dipped or coated with any chemical, whilst the DMPK-A and B cards are coated with a proprietary mixture of chemicals that facilitate the denaturation and inactivation of proteins, micro-organisms and cells respectively. The DMPK-A and B cards have been designed to facilitate the storage of nucleic acids. Therefore the low IL-2 recovery levels observed when using the DMPK-A and B cards may actually be a reflection of the presence of these denaturing reagents and the ELISA-based antibody detection system used. The ELISA detection system requires the eluted IL-2 to exhibit an intact native structure. 
         [0000]    
       
         
               
             
               
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 The Recovery of exogenously-added IL-2 from dried blood spots 
               
               
                 applied to various paper types. The p-value compares ±carrier 
               
               
                 for each paper type. The presence of the carrier had no significant 
               
               
                 effect on the recovery of IL-2 (p-value &gt; 0.05). 
               
             
          
           
               
                   
                   
                 IL-2 
                   
               
               
                   
                 Paper type 
                 recovery (%) 
                 p-value 
               
               
                   
                   
               
               
                   
                 903; minus carrier 
                 46.9 ± 13.3 
                 &gt;0.05 
               
               
                   
                 903; plus carrier 
                 50.7 ± 5.8  
               
               
                   
                 DMPK A; minus carrier 
                 2.0 ± 0.0 
                 &gt;0.05 
               
               
                   
                 DMPK A; plus carrier 
                 2.0 ± 0.0 
               
               
                   
                 DMPK B; minus carrier 
                 2.0 ± 0.0 
                 &gt;0.05 
               
               
                   
                 DMPK B; plus carrier 
                 2.0 ± 0.0 
               
               
                   
                 DMPK C; minus carrier 
                 53.9 ± 4.8  
                 &gt;0.05 
               
               
                   
                 DMPK C; plus carrier 
                 45.2 ± 5.4  
               
               
                   
                   
               
             
          
         
       
     
         [0067]    No IL-2 recovery was observed when the cytokine was dissolved in phosphate buffered saline (PBS) irrespective of the paper type used (data not shown). The IL-2 recovery levels observed in the absence of added IL-2 were essentially equivalent to background levels indicating that the EDTA-anti-coagulated blood contain negligible amounts of endogenous IL-2 (data not shown). 
         [0068]    Several chemicals were used to saturation dip the 903 Neonatal STD cards, some of which appeared to facilitate the recovery of elevated IL-2 levels compared to non-dipped papers (p-value&lt;0.05). For the 903 Neonatal STD cards (Table 2 and  FIG. 2 ), chemicals such as poly-vinyl-alcohol, poly-vinyl-pyrolodine, poly-2-ethyl-2-oxazoline, Tween 20, α-β-trehalose, albumin and casein facilitated an IL-2 increased mean recovery&gt;55% compared to ˜45% observed for the corresponding un-dipped paper. 
         [0000]    
       
         
               
             
               
               
               
             
           
               
                 TABLE 2 
               
             
             
               
                   
               
               
                 The Recovery of exogenously-added IL-2 from dried blood spots 
               
               
                 applied to 903 Neonatal STD papers coated with various chemicals. 
               
               
                 The table is derived from 2 independent experiments (n = 
               
               
                 6). The p-value compares the values derived from the dipped 
               
               
                 papers to those derived from the Un-dipped 903 paper. 
               
             
          
           
               
                   
                 IL-2 
                   
               
               
                 Chemical 
                 recovery (%) 
                 p-value 
               
               
                   
               
               
                 Un-dipped 
                 44.9 ± 6.5 
                 n/a 
               
               
                 Poly-vinyl-alcohol (PVA) 
                  62.6 ± 11.2 
                 &lt;0.05 
               
               
                 Poly-ethyl-enemine (PEI) 
                 41.8 ± 6.0 
                 &gt;0.05 
               
               
                 Poly-vinyl-pyrolodine (PVP) 
                  62.0 ± 10.9 
                 &lt;0.05 
               
               
                 Inulin 
                 50.4 ± 7.6 
                 &gt;0.05 
               
               
                 Poly-2-ethyl-2-oxazoline (PeOX) 
                  66.1 ± 12.6 
                 &lt;0.05 
               
               
                 Tween 20 
                 67.1 ± 9.0 
                 &lt;0.05 
               
               
                 α-β-Trehalose 
                 54.8 ± 8.6 
                 &lt;0.05 
               
               
                 Albumin 
                  73.8 ± 13.6 
                 &lt;0.05 
               
               
                 Caesin 
                 55.0 ± 7.8 
                 &lt;0.05 
               
               
                 Poly-ethylene glycol 1000 (PEG 1000) 
                 42.5 ± 9.1 
                 &gt;0.05 
               
               
                 Poly-ethylene glycol 200 (PEG 200) 
                  43.3 ± 11.0 
                 &gt;0.05 
               
               
                   
               
             
          
         
       
     
         [0069]    The saturation dipping of 903 Neonatal STD papers with a combination of two different chemicals indicated an additive effect in terms of the IL-2 recovery levels. For example, Table 2 demonstrates that the recovery of 903 Neonatal STD papers coated with Tween 20 and Albumin are 67% and 74% respectively. These figures are 22% and 29% greater than the equivalent un-dipped 903 paper respectively. Table 3 shows the cytokine recovery when dried blood spots containing exogenously added IL-2 are applied to 903 Neonatal STD paper co-dipped with both chemicals. The recovery value for the Tween 20/Albumin coated paper is 92% which represents an increase of ˜40% compared to the corresponding un-dipped paper. 
         [0070]    Significantly increased IL-2 recoveries (p-value&lt;0.05) were observed when the 903 paper was co-dipped with the following chemical combinations, Poly-vinyl-pyrolodine (PVP) &amp; Tween 20; Poly-vinyl-pyrolodine (PVP) &amp; Albumin; Tween 20 &amp; Albumin; Poly-2-ethyl-2-oxazoline (PeOX) &amp; Tween 20; Poly-2-ethyl-2-oxazoline (PeOX) &amp; Albumin; Poly-ethyl-enemine (PEI) &amp; Tween 20 and Poly-ethyl-enemine (PEI) &amp; Albumin. 
         [0000]    
       
         
               
             
               
               
               
             
           
               
                 TABLE 3 
               
             
             
               
                   
               
               
                 The Recovery of exogenously added IL-2 from dried 
               
               
                 blood spots applied to 903 Neonatal STD papers coated 
               
               
                 with paired combinations of chemicals (n = 4). 
               
             
          
           
               
                   
                 IL-2 
                   
               
               
                 Chemical 
                 recovery (%) 
                 p-value 
               
               
                   
               
               
                 Un-dipped 
                 50.7 ± 4.9  
                 n/a 
               
               
                 Poly-vinyl-pyrolodine (PVP) &amp; 
                 48.1 ± 13.4 
                 &gt;0.05 
               
               
                 Poly-2-ethyl-2-oxazoline (PeOX) 
               
               
                 Poly-vinyl-pyrolodine (PVP) &amp; Tween 20 
                 79.4 ± 18.8 
                 &lt;0.05 
               
               
                 Poly-vinyl-pyrolodine (PVP) &amp; Albumin 
                 70.5 ± 13.2 
                 &lt;0.05 
               
               
                 Tween 20 &amp; Albumin 
                 92.0 ± 11.0 
                 &lt;0.05 
               
               
                 Poly-2-ethyl-2-oxazoline (PeOX) &amp; 
                 80.9 ± 21.1 
                 &lt;0.05 
               
               
                 Tween 20 
               
               
                 Poly-2-ethyl-2-oxazoline (PeOX) &amp; 
                 89.3 ± 18.9 
                 &lt;0.05 
               
               
                 Albumin 
               
               
                 Poly-2-ethyl-2-oxazoline (PeOX) &amp; 
                 61.8 ± 15.8 
                 &gt;0.05 
               
               
                 Poly-ethyl-enemine (PEI) 
               
               
                 Poly-ethyl-enemine (PEI) &amp; Tween 20 
                 66.8 ± 6.2  
                 &lt;0.05 
               
               
                 Poly-ethyl-enemine (PEI) &amp; Albumin 
                 75.8 ± 13.1 
                 &lt;0.05 
               
               
                 Poly-vinyl-pyrolodine (PVP) &amp; 
                 56.4 ± 11.0 
                 &gt;0.05 
               
               
                 Poly-ethyl-enemine (PEI) 
               
               
                   
               
             
          
         
       
     
         [0071]    While preferred illustrative embodiments of the present invention are described, one skilled in the art will appreciate that the present invention can be practised by other than the described embodiments, which are presented for the purposes of illustration only and not by way of limitation. The present invention is limited only by the claims that follow.

Technology Classification (CPC): 8