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Electrochemical Approaches to Aptamer-Based Sensing

  • Yi Xiao
  • Kevin W. Plaxco
Part of the Integrated Analytical Systems book series (ANASYS)

Abstract

Motivated by the potential convenience of electronic detection, a wide range of electrochemical, aptamer-based sensors have been reported since the first was described only in 2005. Although many of these are simply electrochemical, aptamer-based equivalents of traditional immunochemical approaches (e.g., sandwich and competition assays employing electroactive signaling moieties), others exploit the unusual physical properties of aptamers, properties that render them uniquely well suited for application to impedance and folding-based electrochemical sensors. In particular, the ability of electrode-bound aptamers to undergo reversible, binding-induced folding provides a robust, reagentless means of transducing target binding into an electronic signal that is largely impervious to nonspecific signals arising from contaminants. This capability enables the direct detection of specific proteins at physiologically relevant, picomolar concentrations in blood serum and other complex, contaminant-ridden sample matrices.

Keywords

Methylene Blue Redox Mediator Nonspecific Adsorption Sandwich Assay Electrochemical Aptasensors 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Notes

Acknowledgments

This work was supported in part by NIH EB002046, by NSF DMR 0099843, by Lawrence Livermore National Laboratory (URP-06–019), and by the Institute for Collaborative Biotechnologies through grant DAAD19-03-D-0004 from the US Army Research Office.

References

  1. 1.
    Potyrailo, R.A., Conrad, R.C., Ellington, A.D. and Hieftje, G.M. (1998) Adapting selected nucleic acid ligands (aptamers) to biosensors. Anal. Chem. 70:3419–3425.CrossRefGoogle Scholar
  2. 2.
    Tombelli, S., Minunni, M., Luzi, E. and Mascini, M. (2004) New trends in nucleic acids based biosensors. Anal. Lett. 37:1037–1052.CrossRefGoogle Scholar
  3. 3.
    Dittmer, W.U., Reuter, A. and Simmel, F.C. (2004) A DNA-based machine that can cyclically bind and release thrombin. Angew. Chem. Int. Ed. 43:3550–3553.CrossRefGoogle Scholar
  4. 4.
    Zhang, Z.R., Blank, M. and Schluesener, H.J. (2004) Nucleic acid aptamers in human viral disease. Arch. Immunol. Ther. Exp. 52:307–315.Google Scholar
  5. 5.
    Proske, D., Blank, M., Buhmann, R. and Resch, A. (2005) Aptamers: basic research, drug development, and clinical applications. Appl. Microbiol. Biotechnol. 69:367–374.CrossRefGoogle Scholar
  6. 6.
    Liao, W., Guo, S. and Zhao, X.S. (2006) Novel probes for protein chip applications. Front. Biosci. 11:186–197.CrossRefGoogle Scholar
  7. 7.
    Bakker, E. and Qin, Y. (2006) Electrochemical sensors. Anal. Chem. 78:3965–3983.CrossRefGoogle Scholar
  8. 8.
    Kuhr, W.G. (2000) Electrochemical DNA analysis comes of age. Nat. Biotechnol. 18:1042–1043.CrossRefGoogle Scholar
  9. 9.
    Willner, I. (2002) Biomaterials for sensors, fuel cells, and circuitry. Science 298:2407–2408.CrossRefGoogle Scholar
  10. 10.
    Fritz, J., Cooper, E.B., Gaudet, S., Sorger, P.K. and Manalis, S.R. (2002) Electronic detection of DNA by its intrinsic molecular charge. Proc. Natl. Acad. Sci. USA 99:14142–14146.CrossRefGoogle Scholar
  11. 11.
    Bard, A.J. and Faulkner, L.R. (2001) Electrochemical methods. Wiley, New York.Google Scholar
  12. 12.
    Gooding, J.J. (2005) Nanostructuring electrodes with carbon nanotubes: a review on electrochemistry and applications for sensing. Electrochim. Acta 50:3049–3060.CrossRefGoogle Scholar
  13. 13.
    Kissinger, P.T. (2005) Biosensors: a perspective. Biosens. Bioelectron. 20:2512–2516.CrossRefGoogle Scholar
  14. 14.
    Crouch, S.R. (2005) Kinetic aspects of analytical chemistry: progress and emerging trends. Anal. Bioanal. Chem. 381:1323–1327.CrossRefGoogle Scholar
  15. 15.
    Willner, I. and Zayats, M. (2007) Electronic aptamer-based sensors. Angew. Chem. Int. Ed. 46:6408–6418.CrossRefGoogle Scholar
  16. 16.
    Shipway, A.N., Katz, E. and Willner, I. (2000) Nanoparticle arrays on surfaces for electronic, optical, and sensor applications. Chem. Phys. Chem. 1:18–52.Google Scholar
  17. 17.
    Savran, C.A., Knudsen, S.M., Ellington, A.D. and Manalis, S.R. (2004) Micromechanical detection of proteins using aptamer-based receptor molecules. Anal. Chem. 76:3194–3198.CrossRefGoogle Scholar
  18. 18.
    Staples, M., Daniel, K., Cima, M.J. and Langer, R. (2006) Application of micro- and nano-electromechanical devices to drug delivery. Pharm. Res. 23:847–863.CrossRefGoogle Scholar
  19. 19.
    Dukhin, A.S. and Goetz, P.J. (2001) Acoustic and electroacoustic spectroscopy characterizing concentrated dispersions emulsions. Adv. Colloid Interface Sci. 92:73–132.CrossRefGoogle Scholar
  20. 20.
    Baldrich, E., Acero, J.L., Reekmans, G., Laureyn, W. and O'Sullivan, C.K. (2005) Displacement enzyme linked aptamer assay. Anal. Chem. 77:4774–4784.CrossRefGoogle Scholar
  21. 21.
    Martin, R., Wardale, R.J., Jones, S.J., Hernandez, P.E. and Patterson, R.L.S. (1991) Monoclonal-antibody sandwich ELISA for the potential detection of chicken meat in mixtures of raw beef and pork. Meat Sci. 30:23–31.CrossRefGoogle Scholar
  22. 22.
    Garcia, T., Martin, R., Rodrigueze, E., Azcona, J.I., Sanz, B. and Hernandez, P.E. (1991) Detection of bovine-milk in ovine milk by a sandwich enzyme-linked immunosorbent-assay (ELISA). J. Food Prot. 54:366–369.Google Scholar
  23. 23.
    Honda, M., Yamamoto, S., Cheng, M., Yasukawa, K., Suzuki, H., Saito, T., Osugi, Y., Tokunaga, T. and Kishimoto, T. (1992) Human soluble IL-6 receptor: its detection and enhanced release by HIV-infection. J. Immunol. 148:2175–2180.Google Scholar
  24. 24.
    Kitamura, K., Matsuda, K., Ide, M., Tokunaga, T. and Honda, M. (1989) A fluorescence sandwich ELISA for detecting soluble and cell-associated human interleukin-2. J. Immunol. Methods 121:281–288.CrossRefGoogle Scholar
  25. 25.
    Krishnan, R., Ghindilis, A.L., Atanasov, P. and Wilkins, E. (1995) Fast amperometric immuno-assay utilizing highly dispersed electrode material. Anal. Lett. 28:2459–2474.Google Scholar
  26. 26.
    Campbell, C.N., de Lumley-Woodyear, T. and Heller, A. (1999) Towards immunoassay in whole blood: separationless sandwich-type electrochemical immunoassay based on in-situ generation of the substrate of the labeling enzyme. Fresenius J. Anal. Chem. 364:165–169.CrossRefGoogle Scholar
  27. 27.
    Eteshola, E. and Leckband, D. (2001) Development and characterization of an ELISA assay in PDMS microfluidic channels. Sens. Actuators B 72:129–133.CrossRefGoogle Scholar
  28. 28.
    Ikebukuro, K., Kiyohara, C. and Sode, K. (2005) Novel electrochemical sensor system for protein using the aptamers in sandwich manner. Biosens. Bioelectron. 20:2168–2172.CrossRefGoogle Scholar
  29. 29.
    Bock, L.C., Griffin, L.C., Latham, J.A., Vermaas, E.H. and Toole, J.J. (1992) Selection of single-stranded-DNA molecules that bind and inhibit human thrombin. Nature (Lond.) 355:564–566.CrossRefGoogle Scholar
  30. 30.
    Mir, M., Vreeke, M. and Katakis, I. (2006) Different strategies to develop an electrochemical thrombin aptasensor. Electrochem. Commun. 8:505–511.CrossRefGoogle Scholar
  31. 31.
    Polsky, R., Gill, R., Kaganovsky, L. and Willner, I. (2006) Nucleic acid-functionalized Pt nanoparticles: catalytic labels for the amplified electrochemical detection of biomolecules. Anal. Chem. 78:2268–2271.CrossRefGoogle Scholar
  32. 32.
    Greer, R.W., Hatipoglu, M. and Glancy, D.L. (1975) Normal ranges and diagnostic value of serum albumin and leucine aminopeptidase activity in Egyptian children. Environ. Child Health December: 301–306.Google Scholar
  33. 33.
    Carvounis, C.P. and Feinfeld, D.A. (2000) A simple estimate of the effect of the serum albumin level on the anion gap. Am. J. Nephrol. 20:369–372.CrossRefGoogle Scholar
  34. 34.
    Hianik, T., Ostatna, V., Zajacova, Z., Stoikova, E. and Evtugyn, G. (2005) Detection of aptamer–protein interactions using QCM and electrochemical indicator methods. Bioinorg. Med. Chem. Lett. 15:291–295.CrossRefGoogle Scholar
  35. 35.
    Hansen, J.A., Wang, J., Kawde, A.N., Xiang, Y., Gothelf, K.V. and Collins, G. (2006) Quantum-dot/aptamer-based ultrasensitive multi-analyte electrochemical biosensor. J. Am. Chem. Soc. 128:2228–2229.CrossRefGoogle Scholar
  36. 36.
    Katz, E. and Willner, I. (2003) Probing biomolecular interactions at conductive and semicon-ductive surfaces by impedance spectroscopy: routes to impedimetric immunosensors, DNA-sensors, and enzyme biosensors. Electroanalysis 15:913–947.CrossRefGoogle Scholar
  37. 37.
    Pejcic, B. and De Marco, R. (2006) Impedance spectroscopy: over 35 years of electrochemical sensor optimization. Electrochim. Acta 51:6217–6229.CrossRefGoogle Scholar
  38. 38.
    Diaz-Gonzalez, M., Gonzalez-Garcia, M.B. and Costa-Garcia, A. (2005) Recent advances in electrochemical enzyme immunoassays. Electroanalysis 17:1901–1918.CrossRefGoogle Scholar
  39. 39.
    Guan, J.G., Miao, Y.Q. and Zhang, Q.J. (2004) Impedimetric biosensors. J. Biosci. Bioeng. 97:219–226.Google Scholar
  40. 40.
    Lillie, G., Payne, P. and Vadgama, P. (2001) Electrochemical impedance spectroscopy as a platform for reagentless bioaffinity sensing. Sens. Actuators B 78:249–256.CrossRefGoogle Scholar
  41. 41.
    Taira, H., Nakano, K., Maeda, M. and Takagi, M. (1993) Electrode modification by long-chain, dialkyl disulfide reagent having terminal dinitrophenyl group and its application to impedimetric immunosensors. Anal. Sci. 9:199–206.CrossRefGoogle Scholar
  42. 42.
    Xu, D.K., Xu, D.W., Yu, X.B., Liu, Z.H., He, W. and Ma, Z.Q. (2005) Label-free electrochemical detection for aptamer-based array electrodes. Anal. Chem. 77:5107–5113.CrossRefGoogle Scholar
  43. 43.
    Schlecht, U., Malave, A., Gronewold, T., Tewes, M. and Lohndorf, M. (2006) Comparison of antibody and aptamer receptors for the specific detection of thrombin with a nanometer gap-sized impedance biosensor. Anal. Chim. Acta 573:65–68.CrossRefGoogle Scholar
  44. 44.
    Radi, A.E., Sanchez, J.L.A., Baldrich, E. and O'Sullivan, C.K. (2005) Reusable impedimetric aptasensor. Anal. Chem. 77:6320–6323.CrossRefGoogle Scholar
  45. 45.
    Cai, H., Lee, T.M.-H. and Hzing, I.-M. (2006) Label-free protein recognition using an aptamer-based impedance measurement assay. Sens. Actuators B 114:433–437.CrossRefGoogle Scholar
  46. 46.
    Le Floch, F., Ho, H.A. and Leclerc, M. (2006) Label-free electrochemical detection of protein based on a ferrocene-bearing cationic polythiophene and aptamers. Anal. Chem. 78:4727–4731.CrossRefGoogle Scholar
  47. 47.
    Rodriquez, M.C., Kawde, A.-N. and Wang, J. (2005) Aptamer biosensor for label-free impedance spectroscopy detection of proteins based on recognition-induced switching of the surface charge. Chem. Commun. 34:4267–4269.CrossRefGoogle Scholar
  48. 48.
    Xu, Y., Yang, L., Ye, X., He, P. and Fang, Y. (2006) An aptamer-based protein biosensor by detecting the amplified impedance signal. Electroanalysis 18:1449–1456.CrossRefGoogle Scholar
  49. 49.
    Radi, A.E. and O'Sullivan, C.K. (2006) Aptamer conformational switch as sensitive electrochemical biosensor for potassium ion recognition. Chem. Commun. 32:3432–3434.CrossRefGoogle Scholar
  50. 50.
    Zayats, M., Huang, Y., Gill, R., Ma, C. and Willner, I. (2006) Label-free and reagentless aptamer-based sensors for small molecules. J. Am. Chem. Soc. 128:13666–13667.CrossRefGoogle Scholar
  51. 51.
    Homola, J., Yeea, S.S. and Gauglitzb, G. (1999) Surface plasmon resonance sensors: review. Sens. Actuators B 54:3–15.CrossRefGoogle Scholar
  52. 52.
    Rahman, M.A., Won, M.S. and Shim, Y.B. (2005) The potential use of hydrazine as an alternative to peroxidase in a biosensor: comparison between hydrazine and HRP-based glucose sensors. Biosens. Bioelectron. 21:257–265.CrossRefGoogle Scholar
  53. 53.
    Homola, J. (2003) Present and future of surface plasmon resonance biosensors. Anal. Bioanal. Chem. 377:528–539.CrossRefGoogle Scholar
  54. 54.
    Andersson, J., Larsson, R., Richter, R., Ekdahl, K.N. and Nilsson, B. (2001) Binding of a model regulator of complement activation (RCA) to a biomaterial surface: surface-bound factor H inhibits complement activation. Biomaterials 22:2435–2443.CrossRefGoogle Scholar
  55. 55.
    Janshoff, A., Galla, H.J. and Steinem, C. (2000) Piezoelectric mass-sensing devices as biosensors: an alternative to optical biosensors? Angew. Chem. Int. Ed. 39:4004–4032.Google Scholar
  56. 56.
    Raiteri, R., Grattarola, M., Butt, H.J. and Skladal, P. (2001) Micromechanical cantilever-based biosensors. Sens. Actuators B 79:115–126.CrossRefGoogle Scholar
  57. 57.
    Zurn, A., Rabolt, B., Grafe, M. and Muller, H. (1994) Advances in photolithographically fabricated ENFET membranes. Fresenius J. Anal. Chem. 349:666–669.CrossRefGoogle Scholar
  58. 58.
    Barbaro, M., Bonfiglio, A., Raffo, L., Alessandrini, A., Facci, P. and Barak, I. (2006) Fully electronic DNA hybridization detection by a standard CMOS biochip. Sens. Actuators B 118:41–46.CrossRefGoogle Scholar
  59. 59.
    Shin, J.K., Kim, D.S., Park, H.J. and Lim, G. (2004) Detection of DNA and protein molecules using an FET-type biosensor with gold as a gate metal. Electroanalysis 16:1912–1918.CrossRefGoogle Scholar
  60. 60.
    Xu, J.J., Luo, X.L. and Chen, H.Y. (2005) Analytical aspects of FET-based biosensors. Front. Biosci. 10:420–430.CrossRefGoogle Scholar
  61. 61.
    Barbaro, M., Bonfiglio, A., Raffo, L., Alessandrini, A., Facci, P. and Barak, I. (2006) A CMOS, fully integrated sensor for electronic detection of DNA hybridization. IEEE Electron. Device Lett. 27:595–597.CrossRefGoogle Scholar
  62. 62.
    Yamamoto, R. and Kumar, P.K.R. (2000) Molecular beacon aptamer fluoresces in the presence of Tat protein of HIV-1. Genes Cells 5:389–396.CrossRefGoogle Scholar
  63. 63.
    Li, J.W.J., Fang, X.H. and Tan, W.H. (2002) Molecular aptamer beacons for real-time protein recognition. Biochem. Biophys. Res. Commun. 292:31–40.CrossRefGoogle Scholar
  64. 64.
    Rajendran, M. and Ellington, A.D. (2003) In vitro selection of molecular beacons. Nucleic Acids Res. 31:5700–5713.CrossRefGoogle Scholar
  65. 65.
    Tan, W.H., Wang, K.M. and Drake, T.J. (2004) Molecular beacons. Curr. Opin. Chem. Biol. 8:547–553.CrossRefGoogle Scholar
  66. 66.
    Lin, C.H. and Patel, D.J. (1997) Structural basis of DNA folding and recognition in an AMP–DNA aptamer complex: distinct architectures but common recognition motifs for DNA and RNA aptamers complexed to AMP. Chem. Biol. 4:817–832.CrossRefGoogle Scholar
  67. 67.
    Baldrich, E., Restrepo, A. and O'Sullivan, C.K. (2004) Aptasensor development: elucidation of critical parameters for optimal aptamer performance. Anal. Chem. 76:7053–7063.CrossRefGoogle Scholar
  68. 68.
    Famulok, M. (1999) Oligonucleotide aptamers that recognize small molecules. Curr. Opin. Struct. Biol. 9:324–329.CrossRefGoogle Scholar
  69. 69.
    Perrin, D.M. (2000) Nucleic acids for recognition and catalysis: landmarks, limitations, and looking to the future. Comb. Chem. High Throughput Screen. 3:243–269.Google Scholar
  70. 70.
    Jhaveri, S.D., Kirby, R., Conrad, R., Maglott, E.J., Bowser, M., Kennedy, R.T., Glick, G. and Ellington, A.D. (2000) Designed signaling aptamers that transduce molecular recognition to changes in fluorescence intensity. J. Am. Chem. Soc. 122:2469–2473.CrossRefGoogle Scholar
  71. 71.
    Tang, J. and Breaker, R.R. (1997) Examination of the catalytic fitness of the hammerhead ribozyme by in vitro selection. RNA 3:914–925.Google Scholar
  72. 72.
    Stojanovic, M.N., de Prada, P. and Landry, D.W. (2001) Aptamer-based folding fluorescent sensor for cocaine. J. Am. Chem. Soc. 123:4928–4931.CrossRefGoogle Scholar
  73. 73.
    Hamaguchi, N., Ellington, A. and Stanton, M. (2001) Aptamer beacons for the direct detection of proteins. Anal. Biochem. 294:126–131.CrossRefGoogle Scholar
  74. 74.
    Hesselberth, J.R., Robertson, M.P., Knudsen, S.M. and Ellington, A.D. (2003) Simultaneous detection of diverse analytes with an aptazyme ligase array. Anal. Biochem. 312:106–112.CrossRefGoogle Scholar
  75. 75.
    Rupcich, N., Chiuman, W., Nutiu, R., Mei, S., Flora, K.K., Li, Y.F. and Brennan, J.D. (2006) Quenching of fluorophore-labeled DNA oligonucleotides by divalent metal ions: implications for selection, design, and applications of signaling aptamers and signaling deoxyribozymes. J. Am. Chem. Soc. 128:780–790.CrossRefGoogle Scholar
  76. 76.
    Oh, K.J., Cash, K.J. and Plaxco, K.W. (2006) Excimer-based peptide beacons: a convenient experimental approach for monitoring polypeptide—protein and polypeptide—oligonucleotide interactions. J. Am. Chem. Soc. 128:14018–14019.CrossRefGoogle Scholar
  77. 77.
    Kohn, J.E. and Plaxco, K.W. (2005) Engineering a signal transduction mechanism for protein-based biosensors. Proc. Natl. Acad. Sci. USA 102:10841–10845.CrossRefGoogle Scholar
  78. 78.
    Bang, G.S., Cho, S. and Kim, B.G. (2005) A novel electrochemical detection method for aptamer biosensors. Biosens. Bioelectron. 21:863–870.CrossRefGoogle Scholar
  79. 79.
    Hamaguchi, N., Ellington, A. and Stanton, M. (2001) Aptamer beacons for the direct detection of proteins. Anal. Biochem. 294:126–131.CrossRefGoogle Scholar
  80. 80.
    Ricci, F., Lai, R.Y., Heeger, A.J. and Plaxco, K.W. (2007) Effect of molecular crowding on the response of an electrochemical DNA sensor. Langmuir 23:6827.CrossRefGoogle Scholar
  81. 81.
    Xiao, Y., Lubin, A.A., Heeger, A.J. and Plaxco, K.W. (2005) Label-free electronic detection of thrombin in blood serum using an aptamer based sensor. Angew. Chem. Int. Ed. 44:5456–5459.CrossRefGoogle Scholar
  82. 82.
    Xiao, Y., Piorek, B.D., Plaxco, K.W. and Heeger, A.J. (2005) A reagentless, signal-on design for electronic aptamer-based sensors via target-induced strand displacement. J. Am. Chem. Soc. 127:17990–17991.CrossRefGoogle Scholar
  83. 83.
    Radi, A.E., Sanchez, J.L.A., Baldrich, E. and O'Sullivan, C.K. (2006) Reagentless, reusable, ultrasensitive electrochemical molecular beacon aptasensor. J. Am. Chem. Soc. 128:117–124.CrossRefGoogle Scholar
  84. 84.
    Sanchez, J.L.A., Baldrich, E., Radi, A.E.G., Dondapati, S., Sanchez, P.L., Katakis, I. and O'Sullivan, C.K. (2006) Electronic “off-on” molecular switch for rapid detection of thrombin. Electroanalysis 18:1957–1962.CrossRefGoogle Scholar
  85. 85.
    Lai, R.Y., Plaxco, K.W. and Heeger, A.J. (2006) Rapid, aptamer-based electrochemical detection of platelet-derived growth factor at picomolar concentrations directly in blood serum. Anal. Chem. 79:229–233.CrossRefGoogle Scholar
  86. 86.
    Baker, B.R., Lai, R.Y., Wood, M.S., Doctor, E.H., Heeger, A.J. and Plaxco, K.W. (2006) An electronic, aptamer-based small molecule sensor for the rapid, reagentless detection of cocaine in adulterated samples and biological fluids. J. Am. Chem. Soc. 128:3138–3139.CrossRefGoogle Scholar
  87. 87.
    Zuo, X., Song, S., Zhang, J., Pan, D., Wang, L. and Fan, C. (2007) A target-responsive electro chemical aptamer switch (TREAS) for reagentless detection of nanomolar ATP. J. Am. Chem. Soc. 129:1042–1043.CrossRefGoogle Scholar
  88. 88.
    Xiao, Y., Rowe, A.A. and Plaxco, K.W. (2006) Electrochemical detection of parts per billion lead via an electrode-bound DNAzyme assembly. J. Am. Chem. Soc. 129:262–263.CrossRefGoogle Scholar
  89. 89.
    Breaker, R.R. and Joyce, G.F. (1994) A DNA enzyme that cleaves RNA. Chem. Biol. 1:223–229.CrossRefGoogle Scholar
  90. 90.
    Breaker, R.R. (2000) Molecular biology: making catalytic DNAs. Science 290:2095–2096.CrossRefGoogle Scholar
  91. 91.
    Faulhammer, D. and Famulok, M. (1996) The Ca2+ ion as a cofactor for a novel RNA-cleaving deoxyribozyme. Angew. Chem. Int. Ed. 35:2837–2841.CrossRefGoogle Scholar
  92. 92.
    Lu, Y. (2002) New transition-metal-dependent DNAzymes as efficient endonucleases and as selective metal biosensors. Chem. Eur. J. 8:4588–4596.CrossRefGoogle Scholar
  93. 93.
    Lu, Y., Liu, J.W., Li, J., Bruesehoff, P.J., Pavot, C.M.B. and Brown, A.K. (2003) New highly sensitive and selective catalytic DNA biosensors for metal ions. Biosens. Bioelectron. 18:529–540.CrossRefGoogle Scholar
  94. 94.
    Li, J. and Lu, Y. (2000) A highly sensitive and selective catalytic DNA biosensor for lead ions. J. Am. Chem. Soc. 122:10466–10467.CrossRefGoogle Scholar
  95. 95.
    Liu, J. and Lu, Y. (2003) Improving fluorescent DNAzyme biosensors by combining inter-and intramolecular quenchers. Anal. Chem. 75:6666–6672.CrossRefGoogle Scholar
  96. 96.
    Swearingen, C.B., Wernette, D.P., Cropek, D.M., Lu, Y. Sweedler, J.V. and Bohn, P.W. (2005) Immobilization of a catalytic DNA molecular beacon on Au for Pb(II) detection. Anal. Chem. 77:442–448.CrossRefGoogle Scholar
  97. 97.
    He, Q., Miller, E.W., Wong, A.P. and Chang, C.J. (2006) A selective fluorescent sensor for detecting lead in living cells. J. Am. Chem. Soc. 128:9316–9317.CrossRefGoogle Scholar
  98. 98.
    Huang, C.C., Huang, Y.F., Cao, Z., Tan, W. and Chang, H.T. (2005) Aptamer-modified gold nanoparticles for colorimetric determination of platelet-derived growth factors and their receptors. Anal. Chem. 77:5735–5741.CrossRefGoogle Scholar
  99. 99.
    Fang, X., Cao, Z., Beck, T. and Tan, W. (2001) Molecular aptamer for real-time oncopro-tein platelet-derived growth factor monitoring by fluorescence anisotropy. Anal. Chem. 73:5752–5757.CrossRefGoogle Scholar
  100. 100.
    Fang, X., Sen, A., Vicens, M. and Tan, W. (2003) Synthetic DNA aptamers to detect protein molecular variants in a high-throughput fluorescence quenching assay. ChemBioChem 4:829–834.CrossRefGoogle Scholar
  101. 101.
    Yang, C.J., Jockusch, S., Vicens, M., Turro, N.J. and Tan, W. (2005) Light-switching exci-mer probes for rapid protein monitoring in complex biological fluids. Proc. Natl. Acad. Sci. USA 102:17278–17283.CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media, LLC 2009

Authors and Affiliations

  • Yi Xiao
    • 1
  • Kevin W. Plaxco
    • 2
  1. 1.Department of Physics, Materials Department, Department of Chemistry and BiochemistryUniversity of CaliforniaSanta Barbara
  2. 2.Department of Chemistry and Biochemistry, Interdepartmental program in Biomolecular Science and EngineeringUniversity of CaliforniaSanta Barbara

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