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Enhanced angiography based on magnetic resonance imaging (MRI) has emerged as a noninvasive, robust, and high-resolution imaging technique for the clinical evaluation of vascular diseases. However, the effects of clinical Gd-chelating contrast agents are unsatisfactory for MRI contrast enhancement owing to their short blood half-life caused by rapid vascular extravasation, especially in microvessels. To address these issues, nanoprobes based on red blood cell membrane-coated ultrasmall NaGdF4nanoparticles that exhibit much higher longitudinal molar relaxivity (r1) than the clinically used contrast agent gadolinium diethylenetriaminepentaacetic acid have been developed. Furthermore, the appropriate hydrodynamic diameter and stealth nature aid the nanoprobes to reside longer within the blood vessels without extravasation, thereby increasing the contrast between the blood vessels and surrounding tissues. Through probe-enhanced three-dimensional (3D) dynamic contrast-enhanced MR angiography, the main arteries and veins of the mouse were readily discernible, and even tiny vessels with sub-millimeter diameters could be clearly depicted. With this level of outstanding MR angiography performance, the embolization and recanalization processes of the carotid artery can be serially monitored with high imaging resolution using only a single injection. Additionally, the results of clearance studies and the toxicity tests further highlight the safety features of the nanoprobe. To summarize, the nanoprobes used in this study exhibit less extravascular leakage and a longer blood half-life, thus successfully overcoming the defects of the conventional low-molecular-weight Gd-based contrast agents and demonstrating their potential usefulness in enhanced MR angiography.

Improving the effectiveness of cancer therapy will require tools that enable more specific cancer targeting and improved tumor visualization. Theranostics have the potential for improving cancer care because of their ability to serve as both diagnostics and therapeutics; however, their diagnostic potential is often limited by tissue-associated light absorption and scattering. Herein, we develop CuInSe2@ZnS:Mn quantum dots (QDs) with intrinsic multifunctionality that both enable the accurate localization of small metastases and act as potent tumor ablation agents. By leveraging the growth kinetics of a ZnS shell on a biocompatible CuInSe2core, Mn doping, and folic acid functionalization, we produce biocompatible QDs with high near-infrared (NIR)-II fluorescence efficiency up to 31.2%, high contrast on magnetic resonance imaging (MRI), and preferential distribution in 4T1 breast cancer tumors. MRI-enabled contrast of these nanoprobes is sufficient to timely identify small metastases in the lungs, which is critically important for preventing cancer spreading and recurrence. Further, exciting tumor-resident QDs with NIR light produces both fluorescence for tumor visualization through radiative recombination pathways as well as heat and radicals through nonradiative recombination pathways that kill cancer cells and initiate an anticancer immune response, which eliminates tumor and prevents tumor regrowth in 80% of mice.

Near-infrared (NIR) light-triggered shape memory polymers are expected to have a more promising prospect in biomedical applications compared with traditional heat-triggered shape memory polymers. In this work, a new kind of polyurethane with NIR light-triggered shape memory property was prepared by using polycaprolactone (PCL), polydopamine nanoparticles (PDANPs), hexamethylene diisocyanate (HDI), and 1,4-butanediol (BDO). The synthesized PCL–PDA polyurethanes, especially when the weight content of PDANPs was 0.17%, showed excellent mechanical properties because the PDANPs were well-dispersed in polyurethanes by the chain extension reaction. Moreover, it also showed an NIR light-triggered rapid shape recovery because of the photothermal effect of polydopamine. The in vitro and in vivo tests showed that the PCL–PDA polyurethane would not inhibit cell proliferation nor induce a strong host inflammatory response, revealing the non-cytotoxicity and good biocompatibility of the material. In addition, the PCL–PDA polyurethane exhibited excellent in vivo NIR light-triggered shape memory performance under an 808 nm laser with low intensity (0.33 W cm–2), which was harmless to the human skin. These results demonstrated the potential of the PCL–PDA polyurethane in biomedical implant applications.