Surface with 3-Mercaptopropyltriethoxysilane

APTES reacts with-OH groups and introduces-NH2 groups on the tip surface, as shown in Fig. 10. The APTES-tip can interact with negatively charged molecules and also can be used for further modification of the tip. When other groups on the tip are needed, another silanization reagent can be chosen. For example, 3-mercaptopropyltriethoxysilane (MPTS) introduces-SH groups on the tip surface. 

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