Highly efficient dual-modal phosphorescence/computed tomography bioprobes based on an iridium complex and AuNP polyiohexol composite nanoparticles

On the basis of finite-difference time-domain simulations, a novel strategy is developed to prepare highly efficient bis(2-(2′-benzothienyl)pyridinato-N, C³′)iridium (BTP) and AuNP polyiohexol composite nanoparticles (BAPI NPs) as dual-modal phosphorescence/computed tomography (CT) bioprobes. In these bioprobes, BTP and AuNPs are both encapsulated with polyiohexol NPs. All bioprobe components perform two functions here: AuNPs could be used as both a CT contrast agent and a phosphorescence enhancement reagent of BTP with a metal-enhancement fluorescence effect. The results showed that BAPI NPs were almost spherical in shape, with an average size of 50.36 ± 3.8 nm and a higher total contrast agent loading ratio of 69.4%. Fourier transform infrared spectra confirmed that AuNPs and BTP are encapsulated in BAPI NPs. It is shown that they have lower toxicity for tissues and cells, their phosphorescence intensities are 8.27-fold that of BTP polyiohexol NPs (BPI NPs), the average phosphorescence intensity of the BAPI NPs was 1.46 times higher than that of BPI NPs and 5.85 times that of BTP alone in vivo. Improved CT imaging is obtained at a low dose of polyiohexol in vivo. These bioprobes not only have highly efficient and excellent dual-modal imaging, but they also save the use of various materials, indicating that these bioprobes are the potential dual-modal probes of the future.