Over-the-Counter Biosensors: Past, Present, and Future

Abstract

The demand for specific, low cost, rapid, sensitive and easy detection of biomolecules is huge. A well-known example is the glucose meters used by diabetics to monitor their blood glucose levels. Nowadays, a vast majority of the glucose meters are based on electrochemical biosensor technology. The inherent small size and simple construction of the electrochemical transducer and instrument are ideally suited for pointof-care biosensing. Besides glucose, a wide variety of electrochemical biosensors have been developed for the measurements of some other key metabolites, proteins, and nucleic acids. Nevertheless, unlike the glucose meters, limited success has been achieved for the commercialization of the protein and nucleic acid biosensors. In this review article, key technologies on the electrochemical detection of key metabolites, proteins, and DNAs are discussed in detail, with particular emphasis on those that are compatible to home-use setting. Moreover, emerging technologies of lab-on-a-chip microdevices and nanosensors (i.e., silicon and carbon nanotube field-effect sensors) offer opportunities for the construction of new generation biosensors with much better performances. Together with the continuous innovations in the basic components of biosensors (i.e., transducers, biorecognition molecules, immobilization and signal transduction schemes), consumers could soon buy different kinds of biosensing devices in the pharmacy stores.

Keywords: DNA sensors; Home-use biosensors; glucose sensors; metabolite sensors; protein sensors.

Figure 1.

(a) Schematic diagram and (b) photographs of a microneedle-based glucose monitor. From Zimmermann et al., Transducer '03, The 12^th International Conference on Solid State Sensors, Actuators and Microsystems, pp. 99-102. Reprinted with permission from IEEE (© 2003 IEEE).

Figure 2.

A schematic representation of a gold nanoparticle-reconstituted glucose oxidase electrode. From Xiao et al. Science 2003, 299, 1877-1881. Reprinted with permission from AAAS.

Figure 3.

(a) Schematic illustration and (b) photograph of the disposable electrochemical immunosensor diagnosis device. From Liu et al., Anal. Chem. 2007, 79, 7644-7653. Reprinted with permission from ACS.

Figure 4.

A schematic of the label-free electrochemical aptamer-based protein sensor. From Yi Xiao et al., Angew. Chem. Int. Ed. 2005, 44, 5456-5459. Copyright Wiley-VCH Verlag GmbH & Co. KGaA. Reprinted with permission.

Figure 5.

Schematic of the microchip-based electrochemical enzyme immunoassay. From Wang et al., Anal. Chem. 2001, 73, 5323-5327. Reprinted with permission from ACS.

Figure 6.

Schematic of the silicon nanowire sensor for label-free and real-time protein detection. From Patolsky et al., MRS Bulletin 2007, 32, 142-148. Reprinted with permission from MRS.

Figure 7.

Schematic diagram illustrating the mechanism of the molecular beacon type electrochemical DNA sensor. From Fan et al., Proc. Natl, Acad. Sci. USA, 2003, 100, 9134-9137. Copyright (2003) National Academy of Sciences, U.S.A.

Figure 8.

Scanning electron microscope photograph of a silicon nanowire array fabricated by CMOS compatible technology. From Gao et al., Anal. Chem. 2007, 79, 3291-3297. Reprinted with permission from ACS.

Figure 9.

(a) Schematic and (b) photograph of the self-contained, fully integrated DNA biochip developed by Motorola. From Liu et al., Anal. Chem. 2004, 76, 1824-1831. Reprinted with permission from ACS.