ABSTRACT
In the last few years, there has been a growing interest in bio-and immunosensors based on functionalized micromachined cantilevers to detect the presence of specic compounds [1]. Microcantilevers (MCs) are single-side-clamped suspended beams that can operate either as surface stress sensor or as microbalance (Figure 46.1). Changes in the surface properties of the MC through binding or hybridization of analytes to the receptors on the MC will directly in•uence its surface stress, causing the MC to de•ect proportionally to the analytes concentration. Otherwise, the mass of the binding entities anchored on the MC surfaces can be detected due to the decrease in the resonant frequency. In this way, using the following well-known equation, it is possible to estimate the mass increment Δm looking at the frequency shift value Δf:
Δ Δf
f
m
1 2
= − (46.1)
where f0 is the resonant frequency m0 is the mass loading on the MC before binding
46.1 Introduction .................................................................................................................................. 803 46.2 Materials ...................................................................................................................................... 805
46.2.1 Reagents ........................................................................................................................... 805 46.3 Methods ........................................................................................................................................ 805
46.3.1 In Vitro Biochemical Assays Preparatory for MC Protein Binding Experiments .......... 805 46.3.1.1 Enzyme-Linked Immunosorbent Assay .......................................................... 805 46.3.1.2 Immunoprecipitation Assays ........................................................................... 805
46.3.2 MC Fabrication and Measurement Setup ........................................................................ 806 46.3.3 Statistical Data Analysis .................................................................................................. 807 46.3.4 Experimental Procedure .................................................................................................. 807
46.3.4.1 MC Functionalization ...................................................................................... 807 46.3.4.2 “Ab-Ag” Hybridization Experiment ............................................................... 808
46.4 Results .......................................................................................................................................... 808 46.5 Discussion .....................................................................................................................................810 46.6 Future Trends ................................................................................................................................811 Abbreviations ..........................................................................................................................................812 References ...............................................................................................................................................812
