Spectral Photon-Counting CT Imaging of Gold Nanoparticle Labelled Monocytes for Detection of Atherosclerosis: A Preclinical Study

Advances in nano-delivery systems based on diagnosis and theranostics strategy for atherosclerosis

Atherosclerosis (AS) is a chronic systemic inflammatory disease, where early diagnosis and theranostics strategy for AS are crucial for improving outcomes. However, conventional diagnostic techniques are limited in identifying early AS lesions, failing to stop the progression of AS in time. Nano-delivery systems have shown significant potential in AS diagnosis and treatment, offering distinct advantages in plaque identification and enhancing drugs concentration at lesion sites, thereby advancing new-generation theranostics strategy. This review discusses the application of nano-delivery systems based on imaging technology in AS diagnosis, and we further explore recent advancements in combining different imaging technologies with emerging theranostics strategy. In addition, we also discuss the challenges faced by nano-delivery systems for AS diagnosis and theranostics in clinical translation, such as nanoparticle targeting efficiency, cytotoxicity and long-term accumulation, immune clearance and inaccurate disease modelling. Finally, we also provide prospects on nano-delivery systems based on diagnostic and therapeutic strategies.

Multienergy cardiovascular CT imaging: current state and future

Multienergy cardiovascular CT imaging can be defined as data acquisition at 2 (dual-energy) or multiple X-ray energies. Multienergy cardiovascular CT imaging provides additional qualitative and quantitative information such as material maps or virtual monoenergetic images, which are supposed to further improve the quality and diagnostic yield of CT. Recently introduced photon-counting detector CT scanners further address some of the challenges and limitations of previous, conventional CT machines, hereby enhancing and extending the applications of CT for cardiovascular imaging. This review summarizes the technical principles of multienergy cardiovascular CT imaging and addresses the optimization of image quality and discusses the various dual-energy-based applications for coronary, valvular, and myocardial imaging. New developments in regard to k-edge imaging and new contrast media for multienergy cardiovascular CT imaging are being also discussed.

Nanoparticles with "K-edge" Metals Bring "Color" in Multiscale Spectral Photon Counting X-ray Imaging

Preclinical and clinical diagnostics depend greatly on medical imaging, which enables the identification of physiological and pathological processes in living subjects. It is often necessary to use contrast agents to complement anatomical data with functional information or to describe the disease phenotypically. Nanomaterials are used as contrast agents in many advanced bioimaging techniques and applications because of their high payload, physicochemical properties, improved sensitivity, and multimodality. Metals with k-edge energy within the X-ray bandwidth respond to photon counting and spectral X-ray imaging. This Perspective examines the progress made in the emerging area of nanoparticle-based k-edge contrast agents. These nano "k-edge" particles have been explored with spectral photon counting CT (SPCCT) for multiplexed molecular imaging, pushing the boundaries of resolution and capabilities of CT imaging. Design considerations, contrast properties, and biological behavior are discussed in detail. The key applications are highlighted by categorizing these nanomaterials based on their X-ray, k-edge energy, and biological properties, as well as their synthesis, functionalization, and characterization processes. The article delves into the transformative impact of nano "k-edge" particles on early disease detection and other biomedical applications. The review provides further insights into how the "k-edge signatures" of these nanoparticles combined with photon counting technique can be leveraged for quantitative, multicontrast imaging of diseases. We also discuss the status quo of clinically approved nanoparticles for imaging and highlight the challenges such as toxicity and clearance as well as promising clinical perspectives, providing a balanced view of the potential and limitations of these nanomaterials. Furthermore, we discuss the necessary future research efforts required to clinically translate nano "k-edge" particles as SPCCT contrast agents for early disease diagnosis and tracking.

Metallic nanoparticles unveiled: Synthesis, characterization, and their environmental, medicinal, and agricultural applications

Metallic nanoparticles (MNPs) have attracted great interest among scientists and researchers for years due to their unique optical, physiochemical, biological, and magnetic properties. As a result, MNPs have been widely utilized across a variety of scientific fields, including biomedicine, agriculture, electronics, food, cosmetics, and the environment. In this regard, the current review article offers a comprehensive overview of recent studies on the synthesis of MNPs (metal and metal oxide nanoparticles), outlining the benefits and drawbacks of chemical, physical, and biological methods. However, the biological synthesis of MNPs is of great importance considering the biocompatibility and biological activity of certain MNPs. A variety of characterization techniques, including X-ray diffraction, transmission electron microscopy, UV-visible spectroscopy, scanning electron microscopy, dynamic light scattering, atomic force microscopy, Fourier transform infrared spectroscopy, and others, have been discussed in depth to gain deeper insights into the unique structural and spectroscopic properties of MNPs. Furthermore, their unique properties and applications in the fields of medicine, agriculture, and the environment are summarized and deeply discussed. Finally, the main challenges and limitations of MNPs synthesis and applications, as well as their future prospects have also been discussed.

Engineering Nanoplatforms for Theranostics of Atherosclerotic Plaques

Atherosclerotic plaque formation is considered the primary pathological mechanism underlying atherosclerotic cardiovascular diseases, leading to severe cardiovascular events such as stroke, acute coronary syndromes, and even sudden cardiac death. Early detection and timely intervention of plaques are challenging due to the lack of typical symptoms in the initial stages. Therefore, precise early detection and intervention play a crucial role in risk stratification of atherosclerotic plaques and achieving favorable post-interventional outcomes. The continuously advancing nanoplatforms have demonstrated numerous advantages including high signal-to-noise ratio, enhanced bioavailability, and specific targeting capabilities for imaging agents and therapeutic drugs, enabling effective visualization and management of atherosclerotic plaques. Motivated by these superior properties, various noninvasive imaging modalities for early recognition of plaques in the preliminary stage of atherosclerosis are comprehensively summarized. Additionally, several therapeutic strategies are proposed to enhance the efficacy of treating atherosclerotic plaques. Finally, existing challenges and promising prospects for accelerating clinical translation of nanoplatform-based molecular imaging and therapy for atherosclerotic plaques are discussed. In conclusion, this review provides an insightful perspective on the diagnosis and therapy of atherosclerotic plaques.

Gold nanoparticles spectral CT imaging and limit of detectability in a new materials contrast-detail phantom

This study involves the synthesis, characterization, and spectral photon counting CT (SPCCT) imaging of gold nanoparticles tailored for enhancing the contrast of small cancer lesions. We used the modified Turkevich method to produce thiol-capped gold nanoparticles (AuNPs) at different concentrations (20, 15, 10, 5, 2.5, 1.25, 0.6 mg/ml). We thoroughly characterized the AuNPs using Transmission Electron Microscopy (TEM), X-ray diffraction spectroscopy (XRD), Dynamic Light Scattering (DLS), and UV-visible absorption spectroscopy. To assess the AuNPs contrast enhancing performance, we designed and built a new material contrast detail phantom for CT imaging and determined the minimum detectable concentrations of AuNPs in simulated lesions of small diameters (1, 2, 3, and 5 mm). The synthesized AuNPs are spherical with an average size of approximately 20 ± 4 nm, with maximum UV absorption occurring at 527 nm wavelength, and exhibit a face-centered cubic structure of gold according to XRD analysis. The synthesized gold nanoparticles demonstrated high contrast in SPCCT, suggesting their potential as contrast agents for imaging cancer tissues. The AuNPs image contrast was directly proportional to the AuNPs concentration. We are the first to determine that the lowest visually distinguishable contrast was achieved at a gold concentration of 5 mg/ml for a 2 mm simulated lesion. For 1 mm size lesion the smallest visible concentration was 10 mg/ml. This newly developed phantom can be used for determining the minimal concentration required for various high-Z nanoparticles to produce detectable contrast in X-ray imaging for small-size simulated lesions.

Effect of PVP Molecular Weights on the Synthesis of Ultrasmall Cus Nanoflakes: Synthesis, Properties, and Potential Application for Phototheranostics

Copper sulfide nanoparticles (CuS) hold tremendous potential for applications in photothermal therapy (PTT) and photoacoustic imaging (PAI). However, the conventional chemical coprecipitation method often leads to particle agglomeration issues. To overcome this challenge, we utilized polyvinylpyrrolidone (PVP) as a stabilizing agent, resulting in the synthesis of small PVP-CuS nanoparticles named PC10, PCK30, and PC40. Our study aimed to investigate how different molecular weights of PVP influence the nanoparticles' crystalline characteristics and essential properties, especially their photoacoustic and photothermal responses. While prior research on PVP-assisted CuS nanoparticles has been conducted, our study delves deeper into this area, providing insights into optical properties. Remarkably, all synthesized nanoparticles exhibited a crystalline structure, were smaller than 10 nm, and featured an absorbance peak at 1020 nm, indicating their robust photoacoustic and photothermal capabilities. Among these nanoparticles, PC10 emerged as the standout performer, displaying superior photoacoustic properties. Our photothermal experiments demonstrated significant temperature increases in all cases, with PC10 achieving an impressive efficiency of 51%. Moreover, cytotoxicity assays revealed the nanoparticles' compatibility with cells, coupled with an enhanced incidence of apoptosis compared to necrosis. These findings underscore the promising potential of PVP-stabilized CuS nanoparticles for advanced cancer theranostics.

Characteristics and evaluation of atherosclerotic plaques: an overview of state-of-the-art techniques

Atherosclerosis is an important cause of cerebrovascular and cardiovascular disease (CVD). Lipid infiltration, inflammation, and altered vascular stress are the critical mechanisms that cause atherosclerotic plaque formation. The hallmarks of the progression of atherosclerosis include plaque ulceration, rupture, neovascularization, and intraplaque hemorrhage, all of which are closely associated with the occurrence of CVD. Assessing the severity of atherosclerosis and plaque vulnerability is crucial for the prevention and treatment of CVD. Integrating imaging techniques for evaluating the characteristics of atherosclerotic plaques with computer simulations yields insights into plaque inflammation levels, spatial morphology, and intravascular stress distribution, resulting in a more realistic and accurate estimation of plaque state. Here, we review the characteristics and advancing techniques used to analyze intracranial and extracranial atherosclerotic plaques to provide a comprehensive understanding of atheroma.