Direct immobilization of avidin protein on AFM tip functionalized by acrylic acid vapor at RF plasma

Abstract

The atomic force microscopy (AFM) has been used as a force sensor to measure unbinding forces of single bound complexes in the nanonewton and piconewton range. Force spectroscopy measurements can be applied to study both intermolecular and intramolecular interactions of complex biological and synthetic macromolecules. Although the AFM has been extensively used as a nano force sensor, the commercially available cantilever is limited to silicon and silicon nitride. Those materials reduce the adhesion sensitivity with specific surface and/or molecule. Here, we functionalized the AFM tip with carboxylic groups by applying acrylic acid (AA) vapor at radio frequency plasma treatment at 100 W for 5 min. This method provides a remarkable sensitivity enhancement on the functional group interaction specificity. The functionalized tip was characterized by scanning electron microscopy. The electron beam high resolution images have not shown significant tip sharpness modification. Silicon wafers (1 0 0)-no treated and functionalized by AA plasma treatment-were characterized by Auger electron spectroscopy to elucidate the silicon surface sputtering and demonstrate functionalization. The Fourier transform-infrared spectroscopy spectrum shows a high absorbance of avidin protein over the silicon surface functionalized by AA plasma treatment.We carried out force spectroscopy assay to measure the unbinding force between the well-established pair biotin-avidin. At pulling speed of 2 µm/s, we measured the unbinding force of 106 ± 23 pN, which is in good agreement with the literature, demonstrating the effectiveness of the tip functionalization by AA plasma treatment in biological studies.

Enhanced Immobilization of Gold Nanoclusters on Graphite

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Nanobiosensors Based on Chemically Modified AFM Probes: A Useful Tool for Metsulfuron-Methyl Detection

“…The functionalisation components (Si 3 N 4 , APTES, glutaraldehyde and ALS) were characterised by FTIR [54]. Figure 4 shows the FTIR spectra for Si 3 N 4 (Figure 4(a)), Si 3 N 4 reacted with APTES and glutaraldehyde (Figure 4(b)), and Si 3 N 4 after functionalisation with the ALS enzyme-enriched extracts (Figure 4(c)).…”

Fifteen years of Servitude et Grandeur to the application of a biophysical technique in medicine: The tale of AFMBioMed

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“…47 Ten research articles composed this special issue. [48][49][50][51][52][53][54][55][56][57] The last change that was made during the 75 Nine research articles composed this special issue. [76][77][78][79][80][81][82][83][84] At the end of the conference, it was announced that the next one will…”