Cantilever Biosensors

M. Sepaniak, P. Datskos, N. Lavrik, and C. Tipple, Microcantilever Transducers A New Approach in Sensor Technology, Anal. Chem. 2002, 74, 568A C. Ziegler, Cantilever-Based Biosensors. Anal. Bioanal. Chem. 2004, 379, 946. 

In contrast to SPFS, SPR, and SPDS are tools that can study biomolecular interactions without external labels. They share the same category of label-free biosensors with the reflectometry interference spectroscopy (RIfS) [46], waveguide spectroscopy [47], quartz crystal microbalance (QCM) [48], micro-cantilever sensors [49], etc. Although the label-free sensors cannot compete with SPFS in terms of sensitivity [11], they are however advantageous in avoiding any additional cost/time in labeling the molecules. In particular, the label-free detection concept eliminates undue detrimental effects originating from the labels that may interfere with the fundamental interaction. In this sense, it is worthwhile to develop and improve such sensors as instruments complementary to those ultra-sensitive sensors that require labels. 

There are hundreds if not thousands of miniaturized biosensors published in literature today. Thus, a selection of only a few of them for a brief description is a difficult task. While the biosensors described here are exceptional examples of miniaturized systems, there are many others that would have deserved a description as well, if the space had been available. A selection has been made to give an overview of interesting biosensors such as DNA microarrays, biosensors coupled with capillary electrophoresis (CE), cantilever-based biosensors, electrochemical systems, optical biosensors, and visions of a p.TAS. The examples are described only briefly, for a complete understanding of the work published, the reader is advised to refer to the original publication. Hopefully, this overview gives a grasp of the interesting biosensors developed in the new miniature world. 

Biosensors based on cantilever action were briefly mentioned above. Nanosized cantilevers have been first used in AFM. Here, intermolecular forces between the cantilever and a smface are detected by monitoring the motion of the cantilever tip. In the case of biosensor applications, they are... 

Low detection limits of 10/xgl were established. Similar approaches for the miniaturization of SPR can be found in literature, however, similar to the miniaturized cantilever biosensor, any surface-active interfering compound in samples will cause significant analytical challenges. Borchers and coworkers used a microchip evanescent waveguide for the detection of realtime DNA hybridization events. A lower detection limit of 0.21 nmol 1 was demonstrated. The authors also showed multi-analyte detection capabilities of their system and suggested that this strategy can be utilized in real-time DNA array format with analysis times as short as 2 min. 

Ziegler, C. (2004) Cantilever-based biosensors. Analytical and Eioanalytical Chemistry, 379, 946-959. 

The working principle of the family of biosensors based on nanomechanical transducers, and specifically on microcantilevers, involves the translation of biochemical reactions into a mechanical movement in the nanometer range. In microcantilever sensors, the biochemical receptor layer is directly in contact with one of the cantilever surface. The biomolecular recognition process between the receptor layer and its corresponding analyte induce... 

Piezoelectric-Excited Millimeter-Sized Cantilever Biosensors... 

Campbell, G. A., Uknalis, J., Tu, S.-I., Mutharasan, R. Detection of Escherichia coli 0157 H7 in ground beef samples using piezoelectric excited millimeter-sized cantilever (PEMC) sensors. Biosensors and Bioelectronics 2007,22 (7), 1296-1302... 

In Part I, we describe several mechanical detectors that modify their mechanical properties as a result of biological interactions. Such mechanical direct biosensors typically sense resonance of the mechanical element, which changes when the target molecule binds to the surface. Piezoelectric biosensors (see Chaps. 1-3) employ a technology that is widely used in a variety of applications (e.g., vapor deposition of metals) and is thus readily available and relatively inexpensive. Cantilever-based systems (see Chaps. 4 and 5) can be miniaturized to micrometer dimensions with attendant benefits for system and sample size. 

AFM biosensors Biosensors using scaiming force microscope Cantilever biosensors Force-based biosensors Force biosensors... 

Biosensors using atomic force microscopes (AFMs) are devices which employ an atomic force microscope for biological recognition events. The principle of biosensors using atomic force microscopy is mainly based on the mass-sensitive detection of binding events that change the deflection of a cantilever whose surface is modified with immobilized bioreceptors. 

Biosensors Using Atomic Force Microscopes, Fig. 1 (a) Basic components and working principle of AFM. A sharp tip fixed at the end of a fiexible cantilever is raster scanned over the surface of a sample. As the tip interacts with the surface, the cantilever deflects, and its deflections are monitored by a laser and a photodiode and then used to reconstruct the topography of the sample, (b) A schematic diagram of AFM as a biosensor in detecting... 

The FABS, whose working principle was very similar to that of the AFM biosensor, was a cantilever-based immunosensor [7]. However, its configuration was much simpler than that of the AFM. Rather than using a piezoceramic translator to pull on intermolecular bonds, it used magnetic particles, which eliminated the need to manually position a tip and sample next to each other with picometer precision and stability. The cantilever-beam force transducer was the only element of the AFM retained by the FABS. 

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