Construction of smart inorganic nanoparticle-based ultrasound contrast agents and their biomedical applications

Ultrasound(US) imaging in combination with US contrast agents(UCAs) is a powerful tool in the modern biomedical field because of its high spatial resolution, easy access to patients and minimum invasiveness.The microbubble-based UCAs have been widely used in clinical diagnosis; however, they are only limited to the blood pool imaging and not applicable to the tissue-penetrated imaging due to their large particle size and structural instability. Inorganic nanoparticles(NPs), such as silica,gold and Fe x O y, featured with both satisfactory echogenic properties and structural stability have the potential to be used as a new generation of UCAs. In this review, we present the most recent progresses in the tailored construction of inorganic UCAs and their biomedical applications in the US imaging-involved fields. Firstly, the typical inorganic NPs with different structures including solid, hollow and multiple-layer forms will be comprehensively introduced in terms of their structure design,physicochemical property, US imaging mechanism and diverse applications; secondly, the recent progress in exploring the gas-generating inorganic NP system for US imaging purpose will be reviewed, and these intelligent UCAs are multifunctional for simultaneous US imaging and disease therapy; thirdly, several nanocomposite platforms newly constructed by combining inorganic UCAs with other functional components will be presented anddiscussed. These multifunctional NPs are capable of further enhancing the imaging resolution by providing more comprehensive anatomical information simultaneously.Last but not the least, the design criteria for developing promising UCAs to satisfy both clinical demands and optimized US imaging capability will be discussed and summarized in this review.

Nanoparticles:Untying the Gordian Knot in Conventional Computed Tomography Imaging

X-ray computed tomography(CT)imaging plays an essential role in disease diagnosis due to its noninvasive,painless mode and superior penetration depth.However,the resolution of the soft tissue and minor lesions remains limited.And the disadvantages of conventional contrast agents,such as their inefficient targeting capability,poor biocompatibility,and short circulation times,are considered intractable in clinical use.To overcome these“Gordian knots,”nanoparticles(NPs)for CT imaging have been developed.The advantages of NPs are their exceptionally high sensitivity to X-ray,better imaging performance in vivos and even therapeutic effects.In particular,based on various designs,NP contrast agents composed of different materials integrate multiple imaging modalities,make up for the inadequacy of a single imaging type,and thus provide more accurate information for diagnosis.This review focuses on NPs for X-ray CT imaging and their multifunctional designs.Some perspectives of crucial problems and prospective challenges are also discussed.

Advanced Nanomaterials for Multimodal Molecular Imaging

The development of multimodal molecular imaging contrast agents based on versatile nanomaterials has recently attracted much attention in disease diagnosis and therapeutic delivery.Contrast agents made from nanoparticles and used for multimodal imaging in vivo provide a multidimensional pathophysiological overview of diseases.This review summarizes recently developed advanced nanomaterials for multimodal molecular imaging.We comprehensively discuss these nanoparticle contrast agents in terms of their targeting modalities,limitations in clinical translation and future directions.