Molecular imaging of cancer cells using plasmon-resonant-enhanced third-harmonic-generation in silver nanoparticles

Molecular imaging of cancer cells with the extensive use of plasmon-resonant-enhanced third-harmonic-generation (THG) in silver nanoparticles is demonstrated. This demonstration was performed in cultured mouse bladder carcinoma cells (MBT2) and the matched cell line with knocked-down Her2/neu expression by RNAi. Strong contrast can be provided by the silver nanoparticles under a THG microscope, through matching surface plasmon wavelength to THG wavelength. The laser wavelength is located in the biological penetration window and laser absorption in nanoparticles is also strongly reduced due to the huge spectral difference between the laser excitation wavelength and the plasmon resonance wavelength. Her2/neu in the cancerous cell membranes also was successfully imaged with THG microscopy by successfully conjugating anti-her2 antibodies with the citrated silver nanoparticles.