Raman Thermometry Nanopipettes in Cancer Photothermal Therapy

Abstract

Raman thermometry based on surface-enhanced Raman scattering has been developed using nanopipettes in cancer cell photothermal therapy (PTT). Gold nanorods (AuNRs) are robustly epoxied on glass pipettes with a high surface coverage of ∼95% and less than 10 nm-wide nanogaps for intracellular thermometry and photothermal cancer therapy. The temperature changes could be estimated from the NC band shifts of 4-fluorophenyl isocyanide (FPNC)-adsorbed AuNRs on the Raman thermometry nanopipette (RTN) surfaces. An intracellular temperature change of ∼2.7 °C produced by altering the [Ca2+] in A431 cells was detected using the RTN in vitro, as checked from fura-2 acetoxymethyl ester (fura-2 AM) fluorescence images. For in vivo experiments, local temperature rises of ∼19.2 °C were observed in the mouse skin, whereas infrared camera images could not tract due to spatial resolution. In addition, a tumor growth suppression was observed in the PTT processes after an administration of the three AuNR-coated nanopipettes combined with a 671 nm laser irradiation for 5 min in 30 days. These results demonstrate not only the localized temperature sensing ability of FPNC-tagged AuNR nanopipettes in cell biology but also anti-cancer effects in photothermal cancer therapy.

The Modification and Applications of Nanopipettes in Electrochemical Analysis

“…As shown in Figure 2d, the nanopipette was coated with gold nanorods (AuNRs) to form a SERS reactive substrate. [30] By collecting SERS signals from molecules adsorbed on the AuNR-coated nanopipette, the surface temperature can be evaluated. And the nanopipette can prevent the nanoparticles from being accumulated in the body for safety therapy.…”

“…SERS, which found in 1974 by Fleischmann, [29] refers to the phenomenon that the Raman scattering signals of adsorbed is greatly enhanced than that of ordinary Raman scattering signal in the excitation region of good metal conductor surfaces or solutions. As shown in Figure 2d, the nanopipette was coated with gold nanorods (AuNRs) to form a SERS reactive substrate [30] . By collecting SERS signals from molecules adsorbed on the AuNR‐coated nanopipette, the surface temperature can be evaluated.…”

“…(d) Nanopipette modified with gold nanorods for the cancer cell photothermal therapy based on surface-enhanced Raman scattering. Reproduced from Ref [30]. with the permission of American Chemical Society.…”

Photothermal plasmonic microballs for non-contact single-cell calcium ionophore delivery in heterogeneous cells

“…We prepared AuNRs as in our previous work. 13 UV-Vis absorption spectroscopy showed a longitudinal mode between 600 nm and 700 nm, suggesting strong resonance integrated with either a 633 nm or a 671 nm laser. The size and shape of the AuNRs were homogeneous with a mean length and an average diameter of ∼65 nm and ∼33 nm, respectively.…”

“…The AuNR surfaces were PEGylated through ligand exchange using thiol-PEG-amine (HS-PEG-NH 2 ) to avoid hexadecyltrimethylammonium bromide (CTAB)-induced cytotoxicity. 13 The -S-PEG-NH 2 chains are known to replace CTAB on the surface of AuNRs by forming a stronger Au–S covalent bond. 14 The production of uniform gold microspheres optimized at pH 12 had been shown to form a self-assembled, negatively-charged, and spherically symmetric shape.…”