Rapid photothermal lysis of the pathogenic bacteria, Escherichia coli using synthesis of gold nanorods.

A photon-to-thermal conversion nanosystem has been developed to rapidly elevate temperatures in poorly thermally conducting media using irradiation of gold nanorods. We first hypothesized that nanoparticles, especially gold nanorods, are capable of generating enough heat to lyse bacteria by heating sample solutions via laser irradiation. To test this, we synthesized Au nanorods (aspect ratio 3-4) and studied optothermal properties of these nanoparticles. The short Au nanorods were more efficient at absorbing 808 nm 450 mW laser irradiations resulting in more efficient temperature increase in glass vials compared to the long rods (aspect ratio -40). In bulk media, these nanoparticles could easily raise the temperature beyond 100 degrees C under continuous wave laser irradiation, enabling immediate cell lysis. Consequently, the pathogenic bacteria, Escherichia coli, within the sample solution are lysed by irradiating of the sample using a near infrared laser.