Figure 3.

Characterization of the surface chemistry of the samples such as AuNP-S_Aand AuNP-S_D. (a, b) SEM images of the microcantilever functionalized with DOPA molecules used in the cantilever bioassay. The dimensions of the microcantilever such as stylus height, cantilever length, and width are shown. (c) The magnified image of the stylus vertex shows uniformly coated AuNPs on the entire microcantilever. (d, e) SEM images of the AuNPs immobilized on the Si substrate functionalized with amino groups and DOPA molecules, respectively. (f) Plot of the average number of AuNPs from the SEM images (n = 5). (g, h) Resonant frequency shift of the microcantilever in every step of the fabrication procedure is measured in air (see Table 1). (i) Plot of the total mass of AuNPs bound to the chemically modified surface measured from the frequency shift of a cantilever due to AuNP binding (n = 3).