Figure 2. Spaser as multimodal contrast agent.

(a,b) Fluorescence image of breast cancer cells (MDA-MB-231) with a single spaser (a) and multiple spasers (b). Pump parameters: wavelength 488 nm; pump pulse width 10 ns; beam diameter 20 μm; energy fluence 80 mJ cm⁻² (a) 150 mJ cm⁻² (b). Incubation time: 10 min (a) and 60 min (b). (c) TEM image of single and clustered spasers on a breast cancer cell (MDA-MB-231) membrane after 30 min cell incubation at 37 °C; (d) PT image of cancer cell labelled with spasers (false colours). Labelling parameters: incubation time, 1 h; temperature, 37 °C; spaser concentration, ∼10¹² cm⁻³. Laser parameters; wavelength, 532 nm; pulse width, 5 ns; pulse rate, 100 Hz; energy fluence, 20 mJ cm⁻². (e) Absorption spectra of uranine (green) and gold NPs (yellow) and normalized PA spectra of spasers in linear (blue) and nonlinear (red) modes at energy fluences of 50 and 110 mJ cm⁻², respectively.