Figure 2
Measuring single particle heat generation using a 2D phospholipid bilayer assay.
(a) The temperature profile of an irradiated AuNS (diameter 150 nm) at the laser intensity P = 2.7 × 106 W/cm2. The temperature decays with increasing distance from the particle center. (b) The biological assay used to map out the temperature profile. The assay consists of a 2D phospholipid bilayer with a well-characterized phase transition and a fluorescent molecule that senses the phase and preferentially partitions into the fluid phase. The surface temperature of the nanoparticle can be extracted by determining one point on the temperature profile, ΔT, in this assay corresponding to half the diameter of the melted footprint, Dm. (c) Optically heating a nanoparticle embedded in the bilayer with a tightly focused laser beam induces local melting. Here is shown representative melted footprints for all three nanoparticles at the same laser intensity, P = 4.3 × 106 W/cm2. The fluorescent images are recorded by acquiring an emission bandwidth of 496 nm–587 nm and the nanoparticles are imaged by recording 594 nm laser light reflected from the nanoparticle. Scale bars are 2 μm. (d) The surface temperature as a function of laser intensity for all three nanoparticles derived from the size of the melted footprints and using equation (1). n = 12 for all datasets and error bars represent one standard deviation (SD).
