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. Author manuscript; available in PMC: 2021 Jul 21.
Published in final edited form as: Analyst. 2020 Jun 16;145(14):4852–4859. doi: 10.1039/d0an00838a

Fig. 1.

Fig. 1

(A) Optical images demonstrate the flexibility of a long-taper nanopipette tip. (B) Scheme of the procedures for surface modification of a pH-sensitive nanopipette (not to scale). (C) SEM images of the nanopipette tip with different AuNP deposition time, ranging from 0 to 120 min. The inset images are the top view of the nanopipette orifice. The scale bar is 100 nm in inset images. (D) The AuNP number density at the tip (2 μm from the apex) as a function of the AuNP deposition time. (E) Typical Raman spectra of 4-MBA from the AuNP-loaded nanopipette tip after different AuNP deposition time. (F) Normalized Raman spectra of 4-MBA after 60 min (blue line) and 120 min (red line) AuNP deposition time.