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. 2023 Dec 31;11(27):2306716. doi: 10.1002/advs.202306716

Figure 2.

Figure 2

Comparison between the HDT SAM‐based and the SpyDirect‐based nanobody (VHH72) surface. A) QCM‐D profile of the coupling of (1) the spyTag‐peptide (maleimide‐modified peptide versus cysteine‐terminated peptide), (2) VHH72‐spyCatcher fusion protein, (3) bovine serum albumin (BSA), and binding of (4) non‐target GFP and (5) SARS‐CoV‐2 spike protein. HDT SAM‐based nanobody experiment uses an HDT‐coated gold QCM‐D sensor, while SpyDirect uses a bare gold QCM‐D sensor. All the mass was calculated in PBS (10 mm, pH 7.4). Atomic force microscopy (AFM) characterization of B) HDT SAM‐ and C) SpyDirect‐based biofunctional electrode surface in PBS (10 mm, pH 7.4). No BSA was added. A computational rule‐based model generated from the QCM‐D results depicting the D) HDT SAM‐ and E) SpyDirect‐based biofunctional electrode surfaces (to scale).