Nanophotothermolysis of multiple scattered cancer cells with carbon nanotubes guided by time-resolved infrared thermal imaging

Abstract

Nanophotothermolysis with long laser pulses for treatment of scattered cancer cells and their clusters is introduced with the main focus on real-time monitoring of temperature dynamics inside and around individual cancer cells labeled with carbon nanotubes. This technique utilizes advanced time- and spatially-resolved thermal radiometry imaging for the visualization of laser-induced temperature distribution in multiple-point absorbing targets. The capability of this approach was demonstrated for monitoring of thermal effects under long laser exposure (from millisecond to seconds, wavelength 1,064 nm, maximum power 1 W) of cervical cancer HeLa cells labeled with carbon nanotubes in vitro. The applications are discussed with a focus on the nanophotothermolysis of small tumors, tumor margins, or micrometastases under the guidance of near-IR and microwave radiometry.

Fig. 1

(a) Schematic of PT radiometry for monitoring temperature distribution during PT cancer therapy in vitro and (b) the HeLa cells after the incubation for 48 h with CNTs.

Fig. 2

High-resolution TEM image of multiwall CNTs (MWCNTs) grown over the Fe-Co/CaCO₃ catalyst, (b) Raman scattering spectra of the MWCNTs produced on the Fe-Co/CaCO₃ catalyst with acetylene as carbon source, and (c) cytotoxicity studies of the MWCNTs in the cervical cancer HeLa cells (48 h).

Fig. 3

Time-resolved PT radiometry imaging of temperature dynamic around cancer cells at various periods of time (“2-D temporal temperature mapping”) during the cw laser exposure (wavelength, 1064 nm; power, 1 W; beam diameter, 2 mm at aperture): (a) optical image (image height, approx. 4.3 mm), and at various time (t) intervals during laser treatment; (b) t=0; (c) t=0.2 s; (d) t=0.6 s; (e) t=1.2 s; (f) t=2.2 s; and (g) t =3.4 s.

Fig. 4

Relationship between the temperature inside and outside the cells at various distances as a function of the irradiation time. The curves from top to bottom represent the temperature inside the laser beam (filled circles), at the outer edge of the beam (hollow circles), 1 (filled triangles), and 2 mm away from the beam (hollow triangles). (b) Completely disintegration of single cell with CNTs (48-h incubation) due to the heating process induced by laser exposure (1064 nm, ~31 W/cm₂, 1 W, 4 s). The measurements were performed in identical conditions. (c) Percentage of HeLa cells (with and without CNTs) that died under laser irradiation (4 s).