Anal. Chem. 2007, 79, 1855-1864
Label-Free DNA Biosensor Based on Localized Surface Plasmon Resonance Coupled with Interferometry Do-Kyun Kim,† Kagan Kerman,† Masato Saito,† Ramachandra Rao Sathuluri,† Tatsuro Endo,‡ Shohei Yamamura,† Young-Soo Kwon,§ and Eiichi Tamiya*,†
School of Materials Science, Japan Advanced Institute of Science & Technology, 1-1 Asahidai, Nomi City, Ishikawa 923-1292, Japan, Department of Mechano-Micro Engineering, Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8502, Japan, and Department of Electrical Engineering, Dong-A University, 840 Hadan-2dong, Saha-gu, Busan 604-714, Korea
In this report, we developed a new optical biosensor in connection with a gold-deposited porous anodic alumina (PAA) layer chip. In our sensor, we observed that the gold deposition onto the chip surface formed a “caplike” layer on the top of the oxide nanostructures in an orderly fashion, so we called this new surface formation a “goldcapped oxide nanostructure”. As a result of its interferometric and localized surface plasmon resonance properties, the relative reflected intensity (RRI) at surface of the chip resulted in an optical pattern that was highly sensitive to the changes in the effective thickness of the biomolecular layer. We demonstrated the method on the detection of picomolar quantities of untagged oligonucleotides and the hybridization with synthetic and PCR-amplified DNA samples. The detection limit of our PAA layer chip was determined as 10 pM synthetic target DNA. The capability of observing both RRI increment and wavelength shift upon biomolecular interactions promises to make our chip widely applicable in various analytical tests. In life sciences, there is a continuously growing interest to find new methods and devices that would provide easy, highly reproducible, and sensitive sensing assays for biomolecular reactions. Surface plasmon resonance (SPR) has been the leading method in the label-free format. SPR relies on the changes in the refractive index (RI) induced by the biomolecular recognition events confined to the interface. The contributions on SPR have caused significant advances in label-free biosensor technology,1-4 and the portable SPR devices have become attractive devices for * To whom correspondence should be addressed: Tel: +81-761-51-1660. Fax: +81-761-51-1665. E-mail:
[email protected]. † Japan Advanced Institute of Science & Technology. ‡ Tokyo Institute of Technology. § Dong-A University. (1) Pattnaik, P. Appl. Biochem. Biotechnol. 2005, 126, 79-92. (2) Lahiri, J.; Isaacs, L.; Tien, J.; Whitesides, G. M. Anal. Chem. 1999, 71, 777-790. (3) Nakamura, R.; Muguruma, H.; Ikebukuro, K.; Sasaki, S.; Nagata, R.; Karube, I.; Pedersen, H. Anal. Chem. 1997, 69, 4649-4652. (4) Kai, E.; Sawata, S.; Ikebukuro, K.; Iida, T.; Honda, T.; Karube, I. Anal. Chem. 1999, 71, 796-800. 10.1021/ac061909o CCC: $37.00 Published on Web 01/30/2007
© 2007 American Chemical Society
on-field applications. Imaging SPR has allowed the implementation of an array format and significantly improved the utility of the SPR technique;5-9 however, its instrumental setup is complicated for the development of handheld devices. In efforts to overcome the problems associated with the conventional SPR-based systems, optical interferometric transducers provided a strong alternative.10-16 A sensor based on inexpensive optically flat thin films of porous silicon was described by Sailor and co-workers.17-19 By illuminating the sensor from the top, Sailor and co-workers,17-19 found an easy solution to an important drawback of SPR, the limited penetration depth,20,21 and detected the biomolecules on the sensor surface. Moreover, Rothberg and co-workers22 reported an interferometric method based on the changes in the reflectivity from specially fabricated substrates that are capable of detecting the binding of as little as an average of 0.2 nm of biomelecules. Pan and Rothberg23 reported the optical detection of biomolecular reactions on nanoporous (5) Jordan, C. E.; Frutos, A. G.; Thiel, A. G.; Corn, R. M. Anal. Chem. 1997, 69, 4939-4947. (6) Goodrich, T. T.; Lee, H. J.; Corn, R. M. J. Am. Chem. Soc. 2004, 126, 40864087. (7) Goodrich, T. T.; Lee, H. J.; Corn, R. M. Anal. Chem. 2004, 76, 6173-6178. (8) Wark, A. W.; Lee, H. J.; Corn, R. M. Anal. Chem. 2005, 77, 3904-3907. (9) Lee, H. J.; Li, Y.; Wark, A. W.; Corn, R. M. Anal. Chem. 2005, 77, 50965100. (10) Woodruff, S. D.; Yeung, E. S. Anal. Chem. 1982, 54, 1174-1178. (11) Tarigan, H. J.; Neill, P.; Kenmore, C. K.; Bornhop, D. J. Anal. Chem. 1996, 68, 1762-1770. (12) Swinney, K.; Markov, D.; Bornhop, D. J. Anal. Chem. 2000, 72, 26902695. (13) Wang, Z.; Bornhop, D. J. Anal. Chem. 2005, 77, 7872-7877. (14) Markov, D. A.; Swinney, K.; Bornhop, D. J. J. Am. Chem. Soc. 2004, 126, 16659-16664. (15) Dancil, K.-P. S.; Greiner, D. P.; Sailor, M. J. J. Am. Chem. Soc. 1999, 121, 7925-7930. (16) Butler, M. A. Appl. Phys. Lett. 1984, 45, 1007. (17) Balconi, L.; Martinelli, M.; Sigon, F.; Vegetti, G. Proc. Control Qual. 1992, 107. (18) Lin, V. S.-Y.; Motesharei, K.; Dancil, K.-P. S.; Sailor, M. J.; Ghadiri, M. R. Science 1997, 278, 840-843. (19) Doan, V. V.; Sailor, M. J. Science 1992, 256, 1791-1792. (20) Boussaad, S.; Pean, J.; Tao, N. J. Anal. Chem. 2000, 72, 222-226. (21) Sota, H.; Hasegawa, Y.; Iwakura, M. Anal. Chem. 1998, 70, 2019-2024. (22) Lu, J.; Strohsahl, C. M.; Miller, B. L.; Rothberg, L. J. Anal. Chem. 2004, 76, 4416-4420. (23) Pan, S.; Rothberg, L. J. Nano Lett. 2003, 3, 811-814.
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aluminum oxide templates. Rothberg and co-workers24 have also recently reported the application of near-null, single-wavelength arrayed imaging reflectometry for biomolecular sensing. The same group has also developed a proteomic biosensor for the detection of enteropathogenic Escherichia coli.25 Nikitin et al.26 developed an interferometric method that detected the phase of a beam reflected under SPR for biosensing and chemical applications. Wu et al.27 developed a high-sensitivity sensor that combined SPR with heterodyne interferometry. Alieva and Konopsky28 prepared a biosensor based on surface plasmon interferometry, which was independent of the variations of liquid’s refraction index. Recently, Ince and Narayanaswamy29 reviewed the performance of interferometry, SPR, and luminescence as biosensors and chemosensors. The research toward miniaturization has led to the discovery of the unique optical characteristics of noble metals at nanoscale sizes, such as Au and Ag nanoparticles.30,31 The intense colors exhibited by the colloidal solutions of noble metal nanoparticles are due to the colloidal SPR phenomenon. The properties of colloidal SPR are strongly dependent on the size, shape, and local environment of the nanoparticles, as described by Mie theory.32 Mie theory describes that there is a restriction for the movement of electrons through the internal metal framework, when the size of the metal particle is scaled down to nanolevel (
