Objective: Photoacoustic(PA) tomography(PAT) has attracted extensive interest because of its optical absorption contrast and ultrasonic detection. This study aims to develop a biocompatible and biodegradable PA contrast agent particularly promising for clinical applications in human body.Methods: In this study, we presented a PA contrast agent: 1, 2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethylene glycol)](DSPE-PEG)-coated superparamagnetic iron oxide(SPIO) nanoparticles(NPs) loaded with indocyanine green(ICG). We used ICG and SPIO NPs because both drugs are approved by the U.S. Food and Drug Administration. Given the strong absorption of near-infrared laser pulses, SPIO@DSPE-PEG/ICG NPs with a uniform diameter of ~28 nm could significantly enhance PA signals.Results: We demonstrated the contrast enhancement of these NPs in phantom and animal experiments, in which the in vivo circulation time of SPIO@DSPE-PEG/ICG NPs was considerably longer than that of free ICG. These novel NPs also displayed a high efficiency of tumor targeting.Conclusions: SPIO@DSPE-PEG/ICG NPs are promising PAT contrast agents for clinical applications.
Key advances in multifunctional magnetic nanoparticles （MNPs） for magnetic resonance （MR） image-guided pho- tothermal therapy of cancer are reviewed. We briefly outline the design and fabrication of such multifunctional MNPs. Bimodal image-guided photothermal therapies （MR/fluorescence and MR/ultrasound） are also discussed.
By adsorbing chitosan(CS)-functionalized Prussian blue(PB) nanoparticles(CS/PB NPs) complexing DNA onto the surface of gas encapsulated microbubbles(MBs), a multifunctional gene delivery system of MBs@CS/PB/DNA was fabricated for photothermally enhanced gene transfection through ultrasound-targeted microbubble destruction. CS/PB NPs of(2.69 ± 0.49) nm could complex DNA effectively when the mass ratio was2:1. It was found that MBs@CS/PB/DNA could enhance ultrasound imaging greatly both in vitro and in vivo. In addition, MBs@CS/PB/DNA could be disrupted by applying a higher-intensity ultrasound irradiation to release CS/PB/DNA, which could effectively transform the nearinfrared(NIR) light into heat to assist the uptake of CS/PB/DNA by cells. With the aid of ultrasound irradiation and NIR light irradiation, the gene transfection efficiency was significantly enhanced to(43.08 ± 1.13) %, much higher than polyethylenimine. Moreover, MBs@CS/PB/DNA showed excellent biocompatibility, encouraging the further exploration of MBs@CS/PB/DNA to be a platform for combined ultrasound image, photothermal therapy, drug delivery, and gene therapy.
