19 F MRI Probes for Multimodal Imaging*

Magnetic resonance imaging (MRI) is one of the most powerful imaging tools today, capable of displaying superior soft-tissue contrast. This review discusses developments in the field of ¹⁹ F MRI multimodal probes in combination with optical fluorescence imaging (OFI), ¹ H MRI, chemical exchange saturation transfer (CEST) MRI, ultrasonography (USG), X-ray computed tomography (CT), single photon emission tomography (SPECT), positron emission tomography (PET), and photoacoustic imaging (PAI). In each case, multimodal ¹⁹ F MRI probes compensate for the deficiency of individual techniques and offer improved sensitivity or accuracy of detection over unimodal counterparts. Strategies for designing ¹⁹ F MRI multimodal probes are described with respect to their structure, physicochemical properties, biocompatibility, and the quality of images.

Recent developments in multimodality fluorescence imaging probes

Multimodality optical imaging probes have emerged as powerful tools that improve detection sensitivity and accuracy, important in disease diagnosis and treatment. In this review, we focus on recent developments of optical fluorescence imaging (OFI) probe integration with other imaging modalities such as X-ray computed tomography (CT), magnetic resonance imaging (MRI), positron emission tomography (PET), single-photon emission computed tomography (SPECT), and photoacoustic imaging (PAI). The imaging technologies are briefly described in order to introduce the strengths and limitations of each techniques and the need for further multimodality optical imaging probe development. The emphasis of this account is placed on how design strategies are currently implemented to afford physicochemically and biologically compatible multimodality optical fluorescence imaging probes. We also present studies that overcame intrinsic disadvantages of each imaging technique by multimodality approach with improved detection sensitivity and accuracy.

A pH-responsive nanoprobe for turn-on 19F-magnetic resonance imaging

A pH-responsive MRI nanoprobe was developed by partially replacing organic linkers in ZIF-8, which displays pH-responsive in vivo¹⁹F MRI ability.

Multifunctional nanoprobes for both fluorescence and 19F magnetic resonance imaging

Fluorescence is widely used for cell imaging due to its high sensitivity and rich color choice but limited for in vivo imaging because of its low light penetration. Meanwhile, magnetic resonance imaging (MRI) is widely applied for in vivo diagnosis but not suitable for cell imaging because of its low resolution. Compared to ¹H-MRI, ¹⁹F-MRI is more suitable for clinical application due to its high sensitivity but fabricating ¹⁹F-MRI probes is a great challenge. Therefore, it is highly desirable to develop a dual-modal imaging probe for both cell fluorescence imaging and in vivo¹⁹F-MRI with high sensitivity and deep penetration. In this study, ¹⁹F moiety loaded nanocomposites with an organic fluorescent core were successfully prepared via a facile strategy by encapsulating organic dyes with oleylamine-functionalized polysuccinimide and 1H,1H,2H,2H-perfluorodecyltriethoxysilane (PDTES). The aggregation of organic fluorescent dyes in the core results in significant fluorescence for optical imaging, while the ¹⁹F moieties on PDTES allow for simultaneous ¹⁹F MRI. Moreover, the nanocomposites exhibited high water dispersibility and excellent biocompatibility. These properties make them promising for both cell imaging and in vivo imaging applications.

A Trimodal Closomer Drug-Delivery System Tailored with Tracing and Targeting Capabilities

The construction and application of a unique monodisperse closomer drug-delivery system (CDDS) integrating three different functionalities onto an icosahedral closo-dodecaborane [B12 ](2-) scaffold is described. Eleven B-OH vertices of [closo-B12 (OH)12 ](2-) were used to attach eleven copies of the anticancer drug chlorambucil and the targeting vector glucosamine through a bifurcating lysine linker. The remaining twelfth vertex was used to attach a fluorescent imaging probe. The presence of multiple glucosamine units offered a monodisperse and highly water-soluble CDDS with a high payload of therapeutic cargo. This array enhanced the penetration of the drug into cancer cells by exploiting the overexpression of GLUT-1 receptors present on cancer cells. About 15-fold enhancement in cytotoxicity was observed for CDDS-1 against Jurkat cells, compared to CDDS-2, which lacks the GLUT-1 targeting glucosamine. A cytotoxicity comparison of CDDS-1 against colorectal RKO cells and its GLUT-1 knock-out version confirmed that GLUT-1 mediates endocytosis. Using fluorescent markers both CDDS-1 and -2 were traced to the mitochondria, a novel target for alkylating agents.