Of mice and molecules: In vivo photoacoustic imaging using semiconducting polymer nanoparticles
(Phys.org) —Photoacoustic imaging is a hybrid biomedical imaging modality, based on the photoacoustic effect, in which non-ionizing laser pulses are delivered into biological tissues. (More specifically, in the photoacoustic effect sound waves form due to pressure changes when a material absorbs varying-intensity modulated or pulsed light. These waves are then detected by, for example, microphones or piezoelectric sensors. The resulting photoacoustic signal is the current or voltage that provides the value indicating how the sound waves vary in time.) Recently, scientists at Stanford University developed a new class of contrast agents for photoacoustic molecular imaging – namely, near-infrared (NIR) light absorbing semiconducting polymer nanoparticles (SPNs) that produce a stronger signal than single-walled carbon nanotubes and gold nanorods – properties that allowed the researchers to perform whole-body lymph-node photoacoustic mapping on living laboratory mice. In addition, these semiconducting polymer nanoparticles possess high structural flexibility, narrow photoacoustic spectral profiles and strong resistance...