Nano-sized CT contrast agents

Nanoparticulated Bimodal Contrast Agent for Ultra-High-Field Magnetic Resonance Imaging and Spectral X-ray Computed Tomography

Bimodal medical imaging based on magnetic resonance imaging (MRI) and computed tomography (CT) is a well-known strategy to increase the diagnostic accuracy. The most recent advances in MRI and CT instrumentation are related to the use of ultra-high magnetic fields (UHF-MRI) and different working voltages (spectral CT), respectively. Such advances require the parallel development of bimodal contrast agents (CAs) that are efficient under new instrumental conditions. In this work, we have synthesized, through a precipitation reaction from a glycerol solution of the precursors, uniform barium dysprosium fluoride nanospheres with a cubic fluorite structure, whose size was found to depend on the Ba/(Ba + Dy) ratio of the starting solution. Moreover, irrespective of the starting Ba/(Ba + Dy) ratio, the experimental Ba/(Ba + Dy) values were always lower than those used in the starting solutions. This result was assigned to lower precipitation kinetics of barium fluoride compared to dysprosium fluoride, as inferred from the detailed analysis of the effect of reaction time on the chemical composition of the precipitates. A sample composed of 34 nm nanospheres with a Ba0.51Dy0.49F2.49 stoichiometry showed a transversal relaxivity (r2) value of 147.11 mM-1·s-1 at 9.4 T and gave a high negative contrast in the phantom image. Likewise, it produced high X-ray attenuation in a large range of working voltages (from 80 to 140 kVp), which can be attributed to the presence of different K-edge values and high Z elements (Ba and Dy) in the nanospheres. Finally, these nanospheres showed negligible cytotoxicity for different biocompatibility tests. Taken together, these results show that the reported nanoparticles are excellent candidates for UHF-MRI/spectral CT bimodal imaging CAs.

Bismuth drug-inspired ultra-small dextran coated bismuth oxide nanoparticles for targeted computed tomography imaging of inflammatory bowel disease

Bismuth (Bi)-based computed tomography (CT) imaging contrast agents (CAs) hold significant promise for diagnosing gastrointestinal diseases due to their cost-effectiveness, heightened sensitivity, and commendable biocompatibility. Nevertheless, substantial challenges persist in achieving an easy synthesis process, remarkable water solubility, and effective targeting ability for the potential clinical transformation of Bi-based CAs. Herein, we show Bi drug-inspired ultra-small dextran coated bismuth oxide nanoparticles (Bi2O3-Dex NPs) for targeted CT imaging of inflammatory bowel disease (IBD). Bi2O3-Dex NPs are synthesized through a simple alkaline precipitation reaction using bismuth salts and dextran as the template. The Bi2O3-Dex NPs exhibit ultra-small size (3.4 nm), exceptional water solubility (over 200 mg mL-1), high Bi content (19.75 %), excellent biocompatibility and demonstrate higher X-ray attenuation capacity compared to clinical iohexol. Bi2O3-Dex NPs not only enable clear visualization of the GI tract outline and intestinal loop structures in CT imaging but also specifically target and accumulate at the inflammatory site in colitis mice after oral administration, facilitating a precise diagnosis and enabling targeted CT imaging of IBD. Our study introduces a novel and clinically promising strategy for synthesizing high-performance Bi2O3-Dex NPs for diagnosing gastrointestinal diseases.

Real-time detection of gastrointestinal leaks via bismuth chelate-enhanced X-ray gastroenterography

Anastomotic leaks are among the most dreaded complications following gastrointestinal (GI) surgery, and contrast-enhanced X-ray gastroenterography is considered the preferred initial diagnostic method for GI leaks. However, from fundamental research to clinical practice, the only oral iodinated contrast agents currently available for GI leaks detection are facing several challenges, including low sensitivity, iodine allergy, and contraindications in patients with thyroid diseases. Herein, we propose a cinematic contrast-enhanced X-ray gastroenterography for the real-time detection of GI leaks with an iodine-free bismuth chelate (Bi-DTPA) for the first time. The Bi-DTPA, synthesized through a straightforward one-pot method, offers distinct advantages such as no need for purification, a nearly 100 % yield, large-scale production capability, and good biocompatibility. The remarkable X-ray attenuation properties of Bi-DTPA enable real-time dynamic visualization of whole GI tract under both X-ray gastroenterography and computed tomography (CT) imaging. More importantly, the leaky site and severity can be both clearly displayed during Bi-DTPA-enhanced gastroenterography in a rat model with esophageal leakage. The proposed movie-like Bi-DTPA-enhanced X-ray imaging approach presents a promising alternative to traditional GI radiography based on iodinated molecules. It demonstrates significant potential in addressing concerns related to iodine-associated adverse effects and offers an alternative method for visually detecting gastrointestinal leaks.

An AIEgen and Iodine Double-Ornamented Platinum(II) Complex for Bimodal Imaging-Guided Chemo-Photodynamic Combination Therapy

Real-time biodistribution monitoring and enhancing the therapeutic efficacy of platinum(II)-based anticancer drugs are urgently required to elevate their clinical performance. Herein, a tetraphenylethene derivative (TP) with aggregation-induced emission (AIE) properties and an iodine atom are selected as ligands to endow platinum (II) complex TP-Pt-I with real-time in vivo self-tracking ability by fluorescence (FL) and computerized tomography (CT) imaging, and improved anticancer efficacy by the combination of chemotherapy and photodynamic therapy. Especially, benefiting from the formation of a donor-acceptor-donor structure between the AIE photosensitizer TP and Pt-I moiety, the heavy atom effects of Pt and I, and the presence of I, TP-Pt-I displayed red-shifted absorption and emission wavelengths, enhanced ROS generation efficiency, and improved CT imaging capacity compared with the pristine TP and the control agent TP-Pt-Cl. As a result, the enhanced intratumoral accumulation of TP-Pt-I loaded nanoparticles is readily revealed by dual-modal FL and CT imaging with high contrast. Meanwhile, the TP-Pt-I nanoparticles show significantly improved tumor growth-inhibiting effects on an MCF-7 xenograft murine model by combining the chemotherapeutic effects of platinum(II) and the photodynamic effects of TP. This self-tracking therapeutic complex thus provides a new strategy for improving the therapeutic outcomes of platinum(II)-based anticancer drugs.

Image-based predictive modelling frameworks for personalised drug delivery in cancer therapy

Personalised drug delivery enables a tailored treatment plan for each patient compared to conventional drug delivery, where a generic strategy is commonly employed. It can not only achieve precise treatment to improve effectiveness but also reduce the risk of adverse effects to improve patients' quality of life. Drug delivery involves multiple interconnected physiological and physicochemical processes, which span a wide range of time and length scales. How to consider the impact of individual differences on these processes becomes critical. Multiphysics models are an open system that allows well-controlled studies on the individual and combined effects of influencing factors on drug delivery outcomes while accommodating the patient-specific in vivo environment, which is not economically feasible through experimental means. Extensive modelling frameworks have been developed to reveal the underlying mechanisms of drug delivery and optimise effective delivery plans. This review provides an overview of currently available models, their integration with advanced medical imaging modalities, and code packages for personalised drug delivery. The potential to incorporate new technologies (i.e., machine learning) in this field is also addressed for development.

Feasibility Analysis of Individualized Low Flow Rate Abdominal Contrast-Enhanced Computed Tomography in Chemotherapy Patients: Dual-Source Computed Tomography With Low Tube Voltage

PURPOSE

The aim of the study is to investigate the feasibility of using dual-source computed tomography (CT) combined with low flow rate and low tube voltage for postchemotherapy image assessment in cancer patients.

METHODS

Ninety patients undergoing contrast-enhanced CT scans of the upper abdomen were prospectively enrolled and randomly assigned to groups A, B, and C (n = 30 each). In group A, patients underwent scans at 120 kVp with 448 mgI/kg. Patients in group B underwent scans at 100 kVp with 336 mgI/kg. Patient in group C underwent scans at 70 kVp with of 224 mgI/kg. Quantitative measurements including the CT number, standard deviation of CT number, signal-to-noise ratio, contrast-to-noise ratio, subjective reader scores, and the volume and flow rate of contrast agent were evaluated for each group.

RESULTS

There was no statistically significant difference in the subjective image scores within the three groups except for the kidney (all P > 0.05). Group C showed significantly higher CT values, lower noise levels, and higher signal-to-noise ratio and contrast-to-noise ratio values in the majority of the regions of interest compared to the other groups (P < 0.05). In group C, the contrast agent dose was decreased by 46% compared to group A (79.48 ± 12.24 vs 42.7 ± 8.6, P < 0.01), and the contrast agent injection rate was reduced by 22% (2.7 ± 0.41 vs 2.1 ± 0.4, P < 0.01).

CONCLUSIONS

The use of 70 kVp tube voltage combined with low iodine flow rates prove to be a more effective approach in solving the challenge of compromised blood vessels in postchemotherapy tumor patients, without reducing image quality and diagnostic confidence.

Facile synthesis of manganese-hafnium nanocomposites for multimodal MRI/CT imaging and in vitro photodynamic therapy of colon cancer

Precise diagnosis of complex and soft tumors is challenging, which limits appropriate treatment options to achieve desired therapeutic outcomes. However, multifunctional nano-sized contrast enhancement agents based on nanoparticles improve the diagnosis accuracy of various diseases such as cancer. Herein, a facile manganese-hafnium nanocomposites (Mn3O4-HfO2 NCs) system was designed for bimodal magnetic resonance imaging (MRI)/computed tomography (CT) contrast enhancement with a complimentary function of photodynamic therapy. The solvothermal method was used to fabricate NCs, and the average size of Mn3O4 NPs and Mn3O4-HfO2 NCs was about 7 nm and 15 nm, respectively, as estimated by TEM. Dynamic light scattering results showed good dispersion and high negative (-33 eV) zeta potential, indicating excellent stability in an aqueous medium. Mn3O4-HfO2 NCs revealed negligible toxic effects on the NCTC clone 929 (L929) and mouse colon cancer cell line (CT26), demonstrating promising biocompatibility. The synthesized Mn3O4-HfO2 NCs exhibit significant enhancement in T1-weighted magnetic resonance imaging (MRI) and X-ray computed tomography (CT), indicating the appropriateness for dual-modal MRI/CT molecular imaging probes. Moreover, ultra-small Mn3O4-HfO2 NCs show good relaxivities for MRI/CT. These nanoprobes Mn3O4-HfO2 NCs further possessed outstanding reactive oxygen species (ROS) generation ability under minute ultraviolet light (6 mW·cm-2) to ablate the colon cancer cells in vitro. Therefore, the designed multifunctional Mn3O4-HfO2 NCs were ideal candidates for cancer diagnosis and photodynamic therapy.

Novel nanoparticle AuNCs conjugated with Desmoglein-3 antibody for FL/CT dual-mode targeted imaging and precise treatment of lung squamous cell carcinoma

Due to lack of effective, early and non-invasive diagnostic as well as treatment tools, the surgical treatment opportunities for lung squamous cell carcinoma (SCC) are limited, resulting in high mortality rates. Therefore, the combination of targeted recognition and precise treatment of lung SCC is of great significance. In this study, a multifunctional nanoparticle is designed and synthesized, which specifically identifies lung SCC cells for target imaging and therapy. Desmoglein-3 (Dsg-3), a transmembrane glycoprotein found in desmosomes, is highly expressed in lung SCC cells. Gold nanoclusters (AuNCs) conjugated with Dsg-3 antibodies to form Au-Dsg-3 through coupling reaction. The results showed that the fluorescence imaging (FI) intensity and computed tomography (CT) signal of Au-Dsg-3 significantly increased within 6 h in vitro and in vivo, achieving dual-modal imaging to detect lung SCC effectively. Besides, Au-Dsg-3 even integrates targeted photothermal therapy (PTT) characteristics in a single nanoparticle. When exposed to near-infrared radiation (NIR), the temperature of the tumor site increased rapidly and reached a high temperature of 53.3 °C after 600 s, causing tumor ablation and growth inhibition. In summary, Au-Dsg-3 provides a key platform for targeted biological imaging and collaborative PTT, which demonstrates good performance on lung SCC.

Calcium-based biomaterials: Unveiling features and expanding applications in osteosarcoma treatment

Calcium, an indispensable element in bone tissues, plays a crucial role in various cellular processes involved in cancer progression. Its ubiquitous yet spatially distinct distribution in the body presents an opportunity to target calcium homeostasis as a novel strategies for cancer treatment, with specific advantages in osteosarcoma therapy. In this comprehensive review, we retrospect the calcium biology intersected with cancer progression, highlight the unveiling features of calcium-based biomaterials in regulating both bone homeostasis and cancer development. We also provide an overview of recent breakthroughs in cancer therapy that leverage calcium biomaterials, showcasing their potential to serve as versatile, customizable platforms for osteosarcoma treatment and as reservoirs for supporting bone reconstruction.

Liposome-camouflaged iodinated mesoporous silica nanoparticles with high loading capacity, high hemodynamic stability, high biocompatibility and high radiopacity

Due to their low osmolality and high tolerability, the highly water-soluble nonionic iodinated contrast agents, such as Ioversol (IV), are widely used as clinical agents for CT imaging. However, their clinical applications still are severely limited by the rapid renal excretion, serious adverse effects especially contrast-induced nephropathy and inefficient targetability. Various nanocarriers have demonstrated tremendous potential for achieving high imaging efficiency and low side effects. However, few nanoparticulate contrast agents can simultaneously integrate the desirable functions for imaging, including high loading capacity of iodine, high structure stability for systemic circulation, high biocompatibility and high radiopacity. Herein, we designed and prepared a kind of new radiopaque liposome-camouflaged iodinated mesoporous silica nanoparticles (OIV-MSNs@Liposomes) as contrast agents in CT imaging. Their composition, structure, morphology, biocompatibility and physicochemical properties as well as in vitro radiopacity were investigated in detail. The results indicated that OIV-MSNs@Liposomes can integrate their individual advantages of liposomes and MSNs, thus exhibiting great potential for use in the CT imaging. Considering the simple preparation process and readily available starting materials as well as enhanced biosafety and high performance in X-ray attenuation, the strategy reported here offers a versatile route to efficiently deliver highly water-soluble nonionic iodinated contrast agents for enhanced CT imaging, which are unattainable by traditional means.

Ultrasmall cerium oxide nanoparticles as highly sensitive X-ray contrast agents and their antioxidant effect

Owing to their theranostic properties, cerium oxide (CeO2) nanoparticles have attracted considerable attention for their key applications in nanomedicine. In this study, ultrasmall CeO2 nanoparticles (particle diameter = 1-3 nm) as X-ray contrast agents with an antioxidant effect were investigated for the first time. The nanoparticles were coated with hydrophilic and biocompatible poly(acrylic acid) (PAA) and poly(acrylic acid-co-maleic acid) (PAAMA) to ensure satisfactory colloidal stability in aqueous media and low cellular toxicity. The synthesized nanoparticles were characterized using high-resolution transmission electron microscopy, X-ray diffraction, Fourier transform-infrared spectroscopy, thermogravimetric analysis, dynamic light scattering, cell viability assay, photoluminescence spectroscopy, and X-ray computed tomography (CT). Their potential as X-ray contrast agents was demonstrated by measuring phantom images and in vivo CT images in mice injected intravenously and intraperitoneally. The X-ray attenuation of these nanoparticles was greater than that of the commercial X-ray contrast agent Ultravist and those of larger CeO2 nanoparticles reported previously. In addition, they exhibited an antioxidant effect for the removal of hydrogen peroxide. The results confirmed that the PAA- and PAAMA-coated ultrasmall CeO2 nanoparticles demonstrate potential as highly sensitive radioprotective or theranostic X-ray contrast agents.

Current trends in gas-synergized phototherapy for improved antitumor theranostics

Phototherapy, such as photothermal therapy (PTT) and photodynamic therapy (PDT), has been considered an elegant solution to eradicate tumors due to its minimal invasiveness and low systemic toxicity. Nevertheless, it is still challenging for phototherapy to achieve ideal outcomes and clinical translation due to its inherent drawbacks. Owing to the unique biological functions, diverse gases have attracted growing attention in combining with phototherapy to achieve super-additive therapeutic effects. Specifically, gases such as nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H2S) have been proven to kill tumor cells by inducing mitochondrial damage in synergy with phototherapy. Additionally, several gases not only enhance the thermal damage in PTT and the reactive oxygen species (ROS) production in PDT but also improve the tumor accumulation of photoactive agents. The inflammatory responses triggered by hyperthermia in PTT are also suppressed by the combination of gases. Herein, we comprehensively review the latest studies on gas-synergized phototherapy for cancer therapy, including (1) synergistic mechanisms of combining gases with phototherapy; (2) design of nanoplatforms for gas-synergized phototherapy; (3) multimodal therapy based on gas-synergized phototherapy; (4) imaging-guided gas-synergized phototherapy. Finally, the current challenges and future opportunities of gas-synergized phototherapy for tumor treatment are discussed. STATEMENT OF SIGNIFICANCE: 1. The novelty and significance of the work with respect to the existing literature. (1) Strategies to design nanoplatforms for gas-synergized anti-tumor phototherapy have been summarized for the first time. Meanwhile, the integration of various imaging technologies and therapy modalities which endow these nanoplatforms with advanced theranostic capabilities has been summarized. (2) The mechanisms by which gases synergize with phototherapy to eradicate tumors are innovatively and comprehensively summarized. 2. The scientific impact and interest. This review elaborates current trends in gas-synergized anti-tumor phototherapy, with special emphases on synergistic anti-tumor mechanisms and rational design of therapeutic nanoplatforms to achieve this synergistic therapy. It aims to provide valuable guidance for researchers in this field.

Dual/Multi-Modal Image-Guided Diagnosis and Therapy Based on Luminogens with Aggregation-Induced Emission

The combination of multiple imaging methods has made an indelible contribution to the diagnosis, surgical navigation, treatment, and prognostic evaluation of various diseases. Due to the unique advantages of luminogens with aggregation-induced emission (AIE), their progress has been significant in the field of organic fluorescent contrast agents. Herein, this manuscript summarizes the recent advancements in AIE molecules as contrast agents for optical image-based dual/multi-modal imaging. We particularly focus on the exceptional properties of each material and the corresponding application in the diagnosis and treatment of diseases.

From Corrosion Casting to Virtual Dissection: Contrast-Enhanced Vascular Imaging using Hafnium Oxide Nanocrystals

Vascular corrosion casting is a method used to visualize the three dimensional (3D) anatomy and branching pattern of blood vessels. A polymer resin is injected in the vascular system and, after curing, the surrounding tissue is removed. The latter often deforms or even fractures the fragile cast. Here, a method is proposed that does not require corrosion, and is based on in situ micro computed tomography (micro-CT) scans. To overcome the lack of CT contrast between the polymer cast and the animals' surrounding soft tissue, hafnium oxide nanocrystals (HfO2 NCs) are introduced as CT contrast agents into the resin. The NCs dramatically improve the overall CT contrast of the cast and allow for straightforward segmentation in the CT scans. Careful design of the NC surface chemistry ensures the colloidal stability of the NCs in the casting resin. Using only 5 m% of HfO2 NCs, high-quality cardiovascular casts of both zebrafish and mice can be automatically segmented using CT imaging software. This allows to differentiate even μ $\umu$ m-scale details without having to alter the current resin injection methods. This new method of virtual dissection by visualizing casts in situ using contrast-enhanced CT imaging greatly expands the application potential of the technique.

Self-Assembled Nano-CT Contrast Agent Leveraging Size Aggregation for Improved In Vivo Tumor CT Imaging

Computed tomography (CT) is a widely utilized noninvasive diagnostic tool in clinical practice. However, the commonly employed small molecular iodinated contrast agents (ICAs) in clinical CT imaging have limitations such as nonspecific distribution in body, rapid clearance through kidneys, etc., leading to a narrow imaging time window. In contrast, existing nano-sized ICAs face challenges like structural uncertainty, poor reproducibility, low iodine content, and uniformity issues. In this study, a novel approach is presented utilizing the aggregation-induced emission luminogen (AIEgen) to design and fabricate a kind of monocomponent nano-sized ICA (namely, BioDHU-CT NPs) that exhibits a unique aggregation effect upon activation. The small sized BioDHU-CT nanoparticles exhibit excellent tumor targeting capabilities and can release ICA modified with AIEgen with a high release efficiency up to 88.45%, under the activation of reactive oxygen species highly expressed in tumor regions. The released ICA performs in situ aggregation capability in the tumor region, which can enhance the retention efficiency of CT contrast agents, extending the imaging time window and improving the imaging quality in tumor regions.

Exploring the Biomedical Potential of PLA/Dysprosium Phosphate Composites via Extrusion-Based 3D Printing: Design, Morphological, Mechanical, and Multimodal Imaging and Finite Element Modeling

The present investigation demonstrates the feasibility of dysprosium phosphate (DyPO4) as an efficient additive in polylactide (PLA) to develop 3D printed scaffolds through the material extrusion (MEX) principle for application in bone tissue engineering. Initially, uniform sized particles of DyPO4 with tetragonal crystal setting are obtained and subsequently blended with different concentrations of PLA to extrude in the form of filaments. A maximum of 20 wt % DyPO4 in PLA matrix has been successfully drawn to yield a defect free filament. The resultant filaments were 3D printed through material extrusion methodology. The structural and morphological analysis confirmed the successful reinforcement of DyPO4 throughout the PLA matrix in all of the 3D printed components. All of the PLA/DyPO4 composites exhibited magnetic resonance imaging and computed tomography contrasting properties, which were dependent on the dysprosium content in the PLA matrix. The detailed mechanical evaluation of the 3D printed PLA/DyPO4 composites ensured good strength accomplished by the reinforcement of 5 wt % DyPO4 in PLA matrix, beyond which a gradual decline in the strength is noticed. Representative volume elements models were developed to realize the intrinsic property of the PLA/DyPO4 composite, and finite element analysis under both static and dynamic loading conditions has been performed to account for the reliability of experimental results.

Functionalized heteroatom-doped carbon dots for biomedical applications: A review

Carbon nanoparticles (CDs) have recently drawn a great attention in (bio)chemical analysis, sensing and bioimaging owing to their photostability, water stability, minimal toxicity, biocompatibility and ease of surface functionalization. While the vast majority of CDs applications rely on exploiting their fluorescent properties, doping such nanomaterials with various elements has recently received increasing attention as an effective approach to modify their optoelectronic characteristics, introducing novel improved optical features such as phosphorescence, upconversion luminescence or multimodal imaging capabilities. This review article focuses in the recent advances on the synthesis of heteroatom-doped CDs, exhibiting distinctive features of high value for sensing and imaging, as well as various functionalization schemes developed for guided analyte labeling. Relevant applications in chemical sensing, bioimaging and disease therapy are here presented. A final section intends to provide an overview towards future developments of such emerging light-emitting nanomaterials in the design of future devices and strategies for (bio)analytical chemistry.

Fluorescence-Based Mono- and Multimodal Imaging for In Vivo Tracking of Mesenchymal Stem Cells

The advancement of stem cell therapy has offered transformative therapeutic outcomes for a wide array of diseases over the past decades. Consequently, stem cell tracking has become significant in revealing the mechanisms of action and ensuring safe and effective treatments. Fluorescence stands out as a promising choice for stem cell tracking due to its myriad advantages, including high resolution, real-time monitoring, and multi-fluorescence detection. Furthermore, combining fluorescence with other tracking modalities-such as bioluminescence imaging (BLI), positron emission tomography (PET), photoacoustic (PA), computed tomography (CT), and magnetic resonance (MR)-can address the limitations of single fluorescence detection. This review initially introduces stem cell tracking using fluorescence imaging, detailing various labeling strategies such as green fluorescence protein (GFP) tagging, fluorescence dye labeling, and nanoparticle uptake. Subsequently, we present several combinations of strategies for efficient and precise detection.

Tungsten-based nanoparticles as contrast agents for liver tumor detection using dual-energy computed tomography

Dual-energy computed tomography (DECT) is a commonly used imaging technique for detecting and diagnosing liver cancer. Currently, it is performed using clinically approved iodinated small molecule contrast agents (CAs). However, these iodinated CAs have several drawbacks, including sub-optimal contrast generation and contra-indication in patients with renal insufficiency. Herein, we synthesized tungsten-based CAs (i.e., WO3-x NPs) with excellent biocompatibility and investigated their effectiveness in DECT imaging. WO3-x NPs significantly enhanced the contrast between liver tumors and normal liver tissues as indicated by in vivo DECT imaging. Furthermore, WO3-x NPs exhibited excellent biocompatibility and minimal systemic toxicity. This study introduces a novel class of CAs for DECT and presents a promising method for accurate early diagnosis of liver tumors.

Fusing Positive and Negative CT Contrast Nanoagent for the Sensitive Detection of Hepatoma

Positive computed tomography (CT) contrast nanoagent has significant applications in diagnosing tumors. However, the sensitive differentiation between hepatoma and normal liver tissue remains challenging. This challenge arises primarily because both normal liver and hepatoma tissues capture the nanoagent, resulting in similar positive CT contrasts. Here, a strategy for fusing positive and negative CT contrast nanoagent is proposed to detect hepatoma. A nanoagent Hf-MOF@AB@PVP initially generates a positive CT contrast signal of 120.3 HU in the liver. Subsequently, it can specifically respond to the acidic microenvironment of hepatoma to generate H2 , further achieving a negative contrast of -96.0 HU. More importantly, the relative position between the negative and positive signals area is helpful to determine the location of hepatoma and normal liver tissues. The distinct contrast difference of 216.3 HU and relative orientation between normal liver and tumor tissues are meaningful to sensitively distinguish hepatoma from normal liver tissue utilizing CT imaging.

Advances of nanomedicine in treatment of atherosclerosis and thrombosis

Atherosclerosis (AS) is a chronic inflammatory vascular disease. Myocardial ischemia originated from AS is the main cause of cardiovascular diseases, one of the major factors contributing to the global disease burden. AS is typically quiescent until occurrence of plaque rupture and thrombosis, leading to acute coronary syndrome and sudden death. Currently, clinical diagnostic techniques suffer from major pitfalls including lack of accuracy and specificity, which makes it rather difficult for drugs to directly target plaques to achieve therapeutic effect. Therefore, how to accurately diagnose and effectively intervene vulnerable AS plaques to achieve accurate delivery of drugs has become an urgent and evolving clinical problem. With the rapid development of nanomedicine and nanomaterials, nanotechnology has shown unique advantages in monitoring vulnerable plaques and thrombus and improving drug efficacy. Recent studies have shown that application of nanoparticle drug delivery system can booster the safety and effectiveness of drug therapy, and molecular imaging technology and nanomedicine also exhibit high clinical application potentials in disease diagnosis. Therefore, nanotechnology provides another promising avenue for diagnosis and treatment of AS and thrombosis, and has shown excellent performance in the development of targeted drug therapy and biomaterials. In this review, the research progress, challenges and prospects of nanotechnology in AS and thrombosis are discussed, expecting to provide new ideas for the prevention, diagnosis and treatment of AS and thrombosis.

Biomedical Approach of Nanotechnology and Biological Risks: A Mini-Review

Nanotechnology has played a prominent role in biomedical engineering, offering innovative approaches to numerous treatments. Notable advances have been observed in the development of medical devices, contributing to the advancement of modern medicine. This article briefly discusses key applications of nanotechnology in tissue engineering, controlled drug release systems, biosensors and monitoring, and imaging and diagnosis. The particular emphasis on this theme will result in a better understanding, selection, and technical approach to nanomaterials for biomedical purposes, including biological risks, security, and biocompatibility criteria.

Water-soluble endohedral metallofullerenes: new horizons for biomedical applications

Endohedral metallofullerenes (EMFs) offer a safe avenue to manipulate metals important to biomedical applications such as MRI contrast, X-ray contrast, radiolabeling, radiotherapy, chemotherapy, and the control of inflammation by scavenging reactive oxygen species (ROS). Moreover, functionalizing the double bonds on the surface of EMFs modifies their solubility, supramolecular behaviour, binding, targeting characteristics, and physical properties. While most existing water-soluble derivatives possess a statistical mixture of appended functional groups, progress has been made in creating molecularly-precise derivatives with a defined number of surface functional groups, leading to potentially more nuanced control of their behaviour and properties. Further elucidation of the structure-function relationships of these materials is expected to enhance their utility in biomedical applications and possibly broaden their use in diverse areas of science and technology.

CT and X-ray contrast agents: Current clinical challenges and the future of contrast

Computed tomography (CT) is a powerful and widely used imaging technique in modern medicine. However, it often requires the use of contrast agents to visualize structures with similar radiographic density. Unfortunately, current clinical contrast agents (CAs) for CT have remained largely unchanged for decades and come with several significant drawbacks, including serious nephrotoxicity and short circulation half-lives. The next generation of CT radiocontrast agents should strive to be long-circulating, non-toxic, and non-immunogenic. Nanoparticle contrast agents have shown promise in recent years and are likely to comprise the majority of next-generation CT contrast agents. This review highlights the fundamental mechanism and background of X-ray and contrast agents. It also focuses on the challenges associated with current clinical contrast agents and provides a brief overview of potential future agents that are based on various materials such as lipids, polymers, dendrimers, metallic, and non-metallic inorganic nanoparticles (NPs). STATEMENT OF SIGNIFICANCE: We realized a need for clarification on a number of concerns related to the use of iodinated contrast material as debates regarding the safety of these agents with patients with kidney disease, shellfish allergies, and thyroid dysfunction remain ongoing in medical practice. This review was partially inspired by debates witnessed in medical practice regarding outdated misconceptions of contrast material that warrant clarification in translational and clinical arenas. Given that conversation around currently available agents is at somewhat of a high water mark, and nanoparticle research has now reached an unprecedented number of readers, we find that this review is timely and unique in the context of recent discussions in the field.

Transition metal compounds: From properties, applications to wettability regulation

Transition metal compounds (TMCs) have the advantages of abundant reserves, low cost, non-toxic and pollution-free, and have attracted wide attention in recent years. With the development of two-dimensional layered materials, a new two-dimensional transition metal carbonitride (MXene) has attracted extensive attention due to its excellent physicochemical properties such as gas selectivity, photocatalytic properties, electromagnetic interference shielding and photothermal properties. They are widely used in gas sensors, oil/water separation, wastewater and waste-oil treatment, cancer treatment, seawater desalination, strain sensors, medical materials and some energy storage materials. In this view, we aim to emphatically summarize MXene with their properties, applications and their wettability regulation in different applications. In addition, the properties of transition metal oxides (TMOs) and other TMCs and their wettability regulation applications are also discussed.

Heavy Metal-Based Nanoparticles as High-Performance X-ray Computed Tomography Contrast Agents

X-ray computed tomography (CT) contrast agents offer extremely valuable tools and techniques in diagnostics via contrast enhancements. Heavy metal-based nanoparticles (NPs) can provide high contrast in CT images due to the high density of heavy metal atoms with high X-ray attenuation coefficients that exceed that of iodine (I), which is currently used in hydrophilic organic CT contrast agents. Nontoxicity and colloidal stability are vital characteristics in designing heavy metal-based NPs as CT contrast agents. In addition, a small particle size is desirable for in vivo renal excretion. In vitro phantom imaging studies have been performed to obtain X-ray attenuation efficiency, which is a critical parameter for CT contrast agents, and the imaging performance of CT contrast agents has been demonstrated via in vivo experiments. In this review, we focus on the in vitro and in vivo studies of various heavy metal-based NPs in pure metallic or chemical forms, including Au, Pt, Pd, Ag, Ce, Gd, Dy, Ho, Yb, Ta, W, and Bi, and provide an outlook on their use as high-performance CT contrast agents.

X-Ray-Induced Drug Release for Cancer Therapy

Drug delivery systems (DDSs) are designed to deliver therapeutic agents to specific target sites while minimizing systemic toxicity. Recent developments in drug-loaded DDSs have demonstrated promising characteristics and paved new pathways for cancer treatment. Light, a prevalent external stimulus, is widely utilized to trigger drug release. However, conventional light sources primarily concentrate on the ultraviolet (UV) and visible light regions, which suffer from limited biological tissue penetration. This limitation hinders applications for deep-tissue tumor drug release. Given their deep tissue penetration and well-established application technology, X-rays have recently received attention for the pursuit of controlled drug release. With precise spatiotemporal and dosage controllability, X-rays stand as an ideal stimulus for achieving controlled drug release in deep-tissue cancer therapy. This article explores the recent advancements in using X-rays for stimulus-triggered drug release in DDSs and delves into their action mechanisms.

Application of Nanoparticles in the Diagnosis of Gastrointestinal Diseases: A Complete Future Perspective

The diagnosis of gastrointestinal (GI) diseases currently relies primarily on invasive procedures like digestive endoscopy. However, these procedures can cause discomfort, respiratory issues, and bacterial infections in patients, both during and after the examination. In recent years, nanomedicine has emerged as a promising field, providing significant advancements in diagnostic techniques. Nanoprobes, in particular, offer distinct advantages, such as high specificity and sensitivity in detecting GI diseases. Integration of nanoprobes with advanced imaging techniques, such as nuclear magnetic resonance, optical fluorescence imaging, tomography, and optical correlation tomography, has significantly enhanced the detection capabilities for GI tumors and inflammatory bowel disease (IBD). This synergy enables early diagnosis and precise staging of GI disorders. Among the nanoparticles investigated for clinical applications, superparamagnetic iron oxide, quantum dots, single carbon nanotubes, and nanocages have emerged as extensively studied and utilized agents. This review aimed to provide insights into the potential applications of nanoparticles in modern imaging techniques, with a specific focus on their role in facilitating early and specific diagnosis of a range of GI disorders, including IBD and colorectal cancer (CRC). Additionally, we discussed the challenges associated with the implementation of nanotechnology-based GI diagnostics and explored future prospects for translation in this promising field.

Cancer Nanomedicine: Emerging Strategies and Therapeutic Potentials

Cancer continues to pose a severe threat to global health, making pursuing effective treatments more critical than ever. Traditional therapies, although pivotal in managing cancer, encounter considerable challenges, including drug resistance, poor drug solubility, and difficulties targeting tumors, specifically limiting their overall efficacy. Nanomedicine's application in cancer therapy signals a new epoch, distinguished by the improvement of the specificity, efficacy, and tolerability of cancer treatments. This review explores the mechanisms and advantages of nanoparticle-mediated drug delivery, highlighting passive and active targeting strategies. Furthermore, it explores the transformative potential of nanomedicine in tumor therapeutics, delving into its applications across various treatment modalities, including surgery, chemotherapy, immunotherapy, radiotherapy, photodynamic and photothermal therapy, gene therapy, as well as tumor diagnosis and imaging. Meanwhile, the outlook of nanomedicine in tumor therapeutics is discussed, emphasizing the need for addressing toxicity concerns, improving drug delivery strategies, enhancing carrier stability and controlled release, simplifying nano-design, and exploring novel manufacturing technologies. Overall, integrating nanomedicine in cancer treatment holds immense potential for revolutionizing cancer therapeutics and improving patient outcomes.

Facilitated encapsulation of a nonionic contrast agent for X-ray computed tomography into lipid vesicles by the multiple emulsification-solvent evaporation method

We studied the encapsulation of iohexol (Ihex), a nonionic contrast agent used for X-ray computational tomography, into lipid vesicles using the multiple emulsification-solvent evaporation method to formulate a nanosized contrast agent. This lipid vesicle preparation method consists of three steps: (1) primary emulsification for producing water-in-oil (W/O) emulsions containing fine water droplets that will be converted to the internal water phase of the lipid vesicles, (2) secondary emulsification for formulating multiple water-in-oil-in-water (W/O/W) emulsions encapsulating the fine water droplets containing Ihex, and (3) solvent evaporation to remove the oil phase solvent (n-hexane) and to form lipid bilayers surrounding the fine inner droplets, resulting in the formation of lipid vesicles encapsulating Ihex. As the diameter and Ihex concentration of the primary W/O emulsion droplets decreased, a higher Ihex encapsulation yield was obtained for the final lipid vesicles. The entrapment yield of Ihex in the final lipid vesicles varied significantly with the emulsifier (Pluronic® F-68) concentration in the external water phase of W/O/W emulsion, and the highest yield (65%) was obtained when the emulsifier concentration was 0.1 wt%. We also investigated the powderization of lipid vesicles encapsulating Ihex via lyophilization. The powderized vesicles were dispersed in water after rehydration and maintained their controlled diameters. The entrapment yield of Ihex in powderized lipid vesicles was maintained for over 1 month at 25 ˚C, while significant leakage of Ihex was observed in the lipid vesicles suspended in the aqueous phase.

Au/Mn nanodot platform for in vivo CT/MRI/FI multimodal bioimaging and photothermal therapy against tongue cancer

Surgical resection is the main method for oral tongue squamous cell carcinoma (OTSCC) treatment. However, the oral physiological function and aesthetics may be seriously damaged during the operation with a high risk of recurrence. Therefore, it is important to develop an alternative strategy with precise guidance for OTSCC treatment. Herein, multifunctional Au/Mn nanodots (NDs) are designed and synthesized. They can perform multimodal bioimaging, including computed tomography (CT) and magnetic resonance imaging (MRI) simultaneously, and exhibit bright near-infrared fluorescence imaging (FI) for navigation, and even integrate photothermal therapy (PTT) property. The localization of OTSCC relies on visual and tactile cues of surgeons while lacking noninvasive pretreament labeling and guidance. Au/Mn NDs provide CT/MRI imaging, giving two means of accurate positioning pretherapy. Meanwhile, the fluorescence of the Au/Mn NDs in the near-infrared region (NIR) is beneficial for noninvasive labeling and intuitive observation with the naked eye to determine the tumor boundary during PTT. Further, Au/Mn NDs showed excellent results in ablating tumors in vivo. Above all, the Au/Mn NDs provide a key platform for multimodal bioimaging and PTT in a single nanoagent, which demonstrated attractive performance for OTSCC treatment.

Advances in nanotechnology for the treatment of GBM

Glioblastoma (GBM), a highly malignant glioma of the central nervous system, is the most dread and common brain tumor with a high rate of therapeutic resistance and recurrence. Currently, the clinical treatment methods are surgery, radiotherapy, and chemotherapy. However, owning to the highly invasive nature of GBM, it is difficult to completely resect them due to the unclear boundary between the edges of GBM and normal brain tissue. Traditional radiotherapy and the combination of alkylating agents and radiotherapy have significant side effects, therapeutic drugs are difficult to penetrate the blood brain barrier. Patients receiving treatment have a high postoperative recurrence rate and a median survival of less than 2 years, Less than 5% of patients live longer than 5 years. Therefore, it is urgent to achieve precise treatment through the blood brain barrier and reduce toxic and side effects. Nanotechnology exhibit great potential in this area. This article summarizes the current treatment methods and shortcomings of GBM, and summarizes the research progress in the diagnosis and treatment of GBM using nanotechnology.

Klotho alleviates contrast-induced acute kidney injury by suppressing oxidative stress, inflammation, and NF-KappaB/NLRP3-mediated pyroptosis

BACKGROUND

Contrast-induced acute kidney injury (CI-AKI) is a common complication following percutaneous coronary intervention in coronary artery disease (CAD) patients with >30% incidence. Klotho is a multifunctional protein that inhibits oxidative stress and inflammation, but its role in CI-AKI is poorly understood. The present study aimed to explore the effects of klotho in CI-AKI.

METHODS

Six-week-old mice and HK-2 were divided into the control, contrast medium (CM), CM + klotho, and klotho groups. H&E staining evaluated kidney injury. Scr and BUN showed renal function. DHE probe and ELISA kit detected the levels of reactive oxygen species (ROS) in kidney tissue, superoxide dismutase (SOD), and malondialdehyde (MDA) in serum. Western blot detected the expressions of NF-κB and phosphorylated NF-κB (p-NF-κB) and pyroptosis-related protein levels of NLRP3, caspase-1, GSDMD, and cleaved-GSDMD in the kidney of CI-AKI mice. CCK-8 and lactate dehydrogenase (LDH) activity assays determined cell viability and damage. Fluorescent probe dichloro-dihydro-fluorescein diacetate (DCFH-DA) and enzyme-linked immunosorbent assay (ELISA) tested oxidative stress-related indicators. These included intracellular reactive oxygen species (ROS), superoxidase dismutase (SOD), and malondialdehyde (MDA). IL-6, TNF-α, IL-1β, and IL-18 in the cell supernatant were tested by ELISA assay and used to reflect inflammation responses. Propidium iodide (PI) staining showed the cell death of HK-2. The expressions of NF-κB, p-NF-κB and pyroptosis-related protein levels of NLRP3, caspase-1, GSDMD, and cleaved-GSDMD were detected by Western blot.

RESULTS

Exogenous klotho administration reduced kidney histopathological alterations and improved renal function in vivo. The levels of reactive oxygen species (ROS) in renal tissue, superoxide dismutase (SOD), and malondialdehyde (MDA) in serum decreased after the klotho intervention. The expression levels of p-NF-κB and pyroptosis-related proteins, including NLRP3, caspase-1, GSDMD, and cleaved-GSDMD, were decreased in CI-AKI mice after the klotho intervention. In vitro, klotho significantly inhibited CM-induced oxidative stress and the production of IL-6 and TNF-α. Moreover, it was found that klotho inhibited the activation of p-NF-κB and down-regulated pyroptosis-related protein (NLRP3, caspase-1, GSDMD, and cleaved-GSDMD).

CONCLUSION

Klotho has a protective effect on CI-AKI via suppressing oxidative stress, inflammation, and NF-κB/NLRP3-mediated pyroptosis that contributes to the potential therapy of CI-AKI.

Multifunctional nanoprobe for multi-mode imaging and diagnosis of metastatic prostate cancer

The high incidence and complex subtypes of prostate cancer put forward higher requirements for accurate diagnosis. Furthermore, advanced prostate cancer is prone to metastasis. Single biological imaging mode faces a challenge of sensitive and fast bioimaging of metastasic prostate cancer. Thus, exploring a nanoprobe with multi-mode imaging function has an important impact on preoperative imaging and intraoperative visualization guide of metastatic prostate cancer. Herein, based on the optical properties and X-ray attenuation capability of Au nanodots as well as the slow electronic relaxation of Gd³⁺, we designed and fabricated the multifunctional nanoprobe Au/Gd nanodots for multi-mode imaging and accurate diagnosis of bone metastatic prostate cancer. The results showed that multiple imaging modes complement each other to achieve high-precision of metastasic prostate cancer detection and accurately guide treatment. In addition, in vitro/vivo experiments showed that Au/Gd nanodots had good biocompatibility and biosafety. Therefore, the prepared multifunctional nanoprobe may provide new strategies and insights for precise diagnosis of metastatic prostate cancer in clinical practice.

Recent advances in Prussian blue-based photothermal therapy in cancer treatment

Malignant tumours are a serious threat to human health. Traditional chemotherapy has achieved breakthrough improvements but also has significant detrimental effects, such as the development of drug resistance, immunosuppression, and even systemic toxicity. Photothermal therapy (PTT) is an emerging cancer therapy. Under light irradiation, the phototherapeutic agent converts optical energy into thermal energy and induces the hyperthermic death of target cells. To date, numerous photothermal agents have been developed. Prussian blue (PB) nanoparticles are among the most promising photothermal agents due to their excellent physicochemical properties, including photoacoustic and magnetic resonance imaging properties, photothermal conversion performance, and enzyme-like activity. By the construction of suitably designed PB-based nanotherapeutics, enhanced photothermal performance, targeting ability, multimodal therapy, and imaging-guided cancer therapy can be effectively and feasibly achieved. In this review, the recent advances in PB-based photothermal combinatorial therapy and imaging-guided cancer therapy are comprehensively summarized. Finally, the potential obstacles of future research and clinical translation are discussed.

Tantalum-Zirconium Co-Doped Metal-Organic Frameworks Sequentially Sensitize Radio-Radiodynamic-Immunotherapy for Metastatic Osteosarcoma

Due to radiation resistance and the immunosuppressive microenvironment of metastatic osteosarcoma, novel radiosensitizers that can sensitize radiotherapy (RT) and antitumor immunity synchronously urgently needed. Here, the authors developed a nanoscale metal-organic framework (MOF, named TZM) by co-doping high-atomic elements Ta and Zr as metal nodes and porphyrinic molecules (tetrakis(4-carboxyphenyl)porphyrin (TCPP)) as a photosensitizing ligand. Given the 3D arrays of ultra-small heavy metals, porous TZM serves as an efficient attenuator absorbing X-ray energy and sensitizing hydroxyl radical generation for RT. Ta-Zr co-doping narrowed the highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) energy gap and exhibited close energy levels between the singlet and triplet photoexcited states, facilitating TZM transfer energy to the photosensitizer TCPP to sensitize singlet oxygen (¹ O₂ ) generation for radiodynamic therapy (RDT). The sensitized RT-RDT effects of TZM elicit a robust antitumor immune response by inducing immunogenic cell death, promoting dendritic cell maturation, and upregulating programmed cell death protein 1 (PD-L1) expression via the cGAS-STING pathway. Furthermore, a combination of TZM, X-ray, and anti-PD-L1 treatments amplify antitumor immunotherapy and efficiently arrest osteosarcoma growth and metastasis. These results indicate that TZM is a promising radiosensitizer for the synergistic RT and immunotherapy of metastatic osteosarcoma.

Plate-Like Colloidal Metal Nanoparticles

The pseudo-two-dimensional (2D) morphology of plate-like metal nanoparticles makes them one of the most anisotropic, mechanistically understood, and tunable structures available. Although well-known for their superior plasmonic properties, recent progress in the 2D growth of various other materials has led to an increasingly diverse family of plate-like metal nanoparticles, giving rise to numerous appealing properties and applications. In this review, we summarize recent progress on the solution-phase growth of colloidal plate-like metal nanoparticles, including plasmonic and other metals, with an emphasis on mechanistic insights for different synthetic strategies, the crystallographic habits of different metals, and the use of nanoplates as scaffolds for the synthesis of other derivative structures. We additionally highlight representative self-assembly techniques and provide a brief overview on the attractive properties and unique versatility benefiting from the 2D morphology. Finally, we share our opinions on the existing challenges and future perspectives for plate-like metal nanomaterials.

Research Progress with Membrane Shielding Materials for Electromagnetic/Radiation Contamination

As technology develops at a rapid pace, electromagnetic and radiation pollution have become significant issues. These forms of pollution can cause many important environmental issues. If they are not properly managed and addressed, they will be everywhere in the global biosphere, and they will have devastating impacts on human health. In addition to minimizing sources of electromagnetic radiation, the development of lightweight composite shielding materials to address interference from radiation has become an important area of research. A suitable shielding material can effectively reduce the harm caused by electromagnetic interference/radiation. However, membrane shielding materials with general functions cannot effectively exert their shielding performance in all fields, and membrane shielding materials used in different fields must have specific functions under their use conditions. The aim of this review was to provide a comprehensive review of these issues. Firstly, the causes of electromagnetic/radiation pollution were briefly introduced and comprehensively identified and analyzed. Secondly, the strategic solutions offered by membrane shielding materials to address electromagnetic/radiation problems were discussed. Then, the design concept, technical innovation, and related mechanisms of the existing membrane shielding materials were expounded, the treatment methods adopted by scholars to study the environment and performance change laws were introduced, and the main difficulties encountered in this area of research were summarized. Finally, on the basis of a comprehensive analysis of the protection provided by membrane shielding materials against electromagnetic/radiation pollution, the action mechanism of membrane shielding materials was expounded in detail, and the research progress, structural design and performance characterization techniques for these materials were summarized. In addition, the future challenges were prospected. This review will help universities, research institutes, as well as scientific and technological enterprises engaged in related fields to fully understand the design concept and research progress of electromagnetic/radiation-contaminated membrane shielding materials. In addition, it is hoped that this review will facilitate efforts to accelerate the research and development of membrane shielding materials and offer potential applications in areas such as electronics, nuclear medicine, agriculture, and other areas of industry.

Radiopaque Nanorobots as Magnetically Navigable Contrast Agents for Localized In Vivo Imaging of the Gastrointestinal Tract

Magnetic nanorobots offer wireless navigation capability in hard-to-reach areas of the human body for targeted therapy and diagnosis. Though in vivo imaging is required for guidance of the magnetic nanorobots toward the target areas, most of the imaging techniques are inadequate to reveal the potential locomotion routes. This work proposes the use of radiopaque magnetic nanorobots along with microcomputed tomography (microCT) for localized in vivo imaging applications. The nanorobots consist of a contrast agent, barium sulfate (BaSO₄ ), magnetized by the decoration of magnetite (Fe₃ O₄ ) particles. The magnetic features lead to actuation under rotating magnetic fields and enable precise navigation in a microfluidic channel used to simulate confined spaces of the body. In this channel, the intrinsic radiopacity of the nanorobots also provides the possibility to reveal the internal structures by X-ray contrast. Furthermore, in vitro analysis indicates nontoxicity of the nanorobots. In vivo experiments demonstrate localization of the nanorobots in a specific part of the gastrointestinal (GI) tract upon the influence of the magnetic field, indicating the efficient control even in the presence of natural peristaltic movements. The nanorobots reported here highlight that smart nanorobotic contrast agents can improve the current imaging-based diagnosis techniques by providing untethered controllability in vivo.

Radiolabeled nanomaterial for cancer diagnostics and therapeutics: principles and concepts

In the last three decades, radiopharmaceuticals have proven their effectiveness for cancer diagnosis and therapy. In parallel, the advances in nanotechnology have fueled a plethora of applications in biology and medicine. A convergence of these disciplines has emerged more recently with the advent of nanotechnology-aided radiopharmaceuticals. Capitalizing on the unique physical and functional properties of nanoparticles, radiolabeled nanomaterials or nano-radiopharmaceuticals have the potential to enhance imaging and therapy of human diseases. This article provides an overview of various radionuclides used in diagnostic, therapeutic, and theranostic applications, radionuclide production through different techniques, conventional radionuclide delivery systems, and advancements in the delivery systems for nanomaterials. The review also provides insights into fundamental concepts necessary to improve currently available radionuclide agents and formulate new nano-radiopharmaceuticals.

In Vitro Hemocompatibility and Genotoxicity Evaluation of Dual-Labeled [99mTc]Tc-FITC-Silk Fibroin Nanoparticles for Biomedical Applications

Nuclear imaging is a highly sensitive and noninvasive imaging technique that has become essential for medical diagnosis. The use of radiolabeled nanomaterials capable of acting as imaging probes has shown rapid development in recent years as a powerful, highly sensitive, and noninvasive tool. In addition, quantitative single-photon emission computed tomography (SPECT) images performed by incorporating radioisotopes into nanoparticles (NPs) might improve the evaluation and the validation of potential clinical treatments. In this work, we present a direct method for [99mTc]Tc-radiolabeling of FITC-tagged silk fibroin nanoparticles (SFN). NPs were characterized by means of dynamic light scattering and scanning electron microscopy. In vitro studies were carried out, including the evaluation of stability in biological media and the evaluation of hemocompatibility and genotoxicity using the cytokinesis block micronucleus (CBMN) assay. The radiolabeling method was reproducible and robust with high radiolabeling efficiency (∼95%) and high stability in biological media. Hydrodynamic properties of the radiolabeled NPs remain stable after dual labeling. The interaction of SFN with blood elicits a mild host response, as expected. Furthermore, CBMN assay did not show genotoxicity induced by [99mTc]Tc-FITC-SFN under the described conditions. In conclusion, a feasible and robust dual-labeling method has been developed whose applicability has been demonstrated in vitro, showing its value for further investigations of silk fibroin NPs biodistribution in vivo.

Emerging and Versatile Platforms of Metal-Ion-Doped Carbon Dots for Biosensing, Bioimaging, and Disease Therapy

Metal ions possess abundant electrons and unoccupied orbitals, as well as large atomic radii, whose doping into carbon dots (CDs) is a facile strategy to endow CDs with additional physicochemical characteristics. After being doped with metal ions, CDs reveal obvious changes in their optical, electronic, and magnetic properties by adjustments to their electron density distribution and the energy gaps, leading them to be promising and competitive candidates as labeling probes, imaging agents, catalysts, nanodrugs, and so on. In this review, we summarize the fabrication methods of metal-ion-doped CDs (M-CDs), and highlight their biological applications including biosensing, bioimaging, tumor therapy, and anti-microbial treatment. Finally, the challenging future perspectives of M-CDs are analyzed. We hope this review will provide inspiration for further development of M-CDs in various biological aspects, and help readers who are interested in M-CDs and their biological applications.

Safety and Feasibility of Contrast-Enhanced Computed Tomography with a Nanoparticle Contrast Agent for Evaluation of Diethylnitrosamine-Induced Liver Tumors in a Rat Model

RATIONALE AND OBJECTIVES

Safety and feasibility of contrast-enhanced computed tomography (CECT) with a nanoparticulate contrast agent, ExiTron nano 12000, was evaluated in a rat liver tumor model.

MATERIALS AND METHODS

This study employed eighteen 8-week-old male F344 rats. Six rats given tap water for 8 weeks further divided into two: Control group and Normal Liver with CECT group. Six rats each were given tap water containing diethylnitrosamine (DEN) at 100 ppm for 8 or 14 weeks; Adenoma group and Hepatocellular carcinoma (HCC) group, respectively. Biochemical marker values and adverse events were evaluated after CT imaging. ExiTron nano 12000 was evaluated for the hepatic contrast enhancement, and the detection and measurement of liver nodules by CECT after 8- and 14-weeks administration of DEN. Post-mortem liver specimens were evaluated by hematoxylin-eosin (HE) staining, and the number and size of liver nodules were measured. The HCC group was evaluated for diagnostic concordance between HE-stained and CECT-detected nodules.

RESULTS

The contrast agent enhanced liver and was tolerated after CECT in 15 rats. Biochemical parameter values did not differ significantly between the Control and Normal Liver groups. The numbers of CECT-detected nodules in the Adenoma and HCC groups were 14.8 ± 5.1, and 32.4 ± 8.1, respectively. The HCC group had 3.6 ± 2.7 of pathological HCCs, which were identified by CECT. The size of CECT-detected HCCs correlated significantly with that of pathological HCCs (r = 0.966, p < 0.0001).

CONCLUSION

CECT with ExiTron nano 12000 is a safe and feasible method to measure tumors in a rat liver tumor model.

Rare-Earth-Metal (Nd3+, Ce3+ and Gd3+)-Doped CaF2: Nanoparticles for Multimodal Imaging in Biomedical Applications

Here, we describe the synthesis of a novel type of rare-earth-doped nanoparticles (NPs) for multimodal imaging, by combining the rare-earth elements Ce, Gd and Nd in a crystalline host lattice consisting of CaF2 (CaF2: Ce, Gd, Nd). CaF2: Ce, Gd, Nd NPs are small (15-20 nm), of uniform shape and size distribution, and show good biocompatibility and low immunogenicity in vitro. In addition, CaF2: Ce, Gd, Nd NPs possess excellent optical properties. CaF2: Ce, Gd, Nd NPs produce downconversion emissions in the second near-infrared window (NIR-II, 1000-1700 nm) under 808 nm excitation, with a strong emission peak at 1056 nm. Excitation in the first near- infrared window (NIR-I, 700-900 nm) has the advantage of deeper tissue penetration power and reduced autofluorescence, compared to visible light. Thus, CaF2: Ce, Gd, Nd NPs are ideally suited for in vivo fluorescence imaging. In addition, the presence of Gd3+ makes the NPs intrinsically monitorable by magnetic resonance imaging (MRI). Moreover, next to fluorescence and MR imaging, our results show that CaF2: Ce, Gd, Nd NPs can be used as imaging probes for photoacoustic imaging (PAI) in vitro. Therefore, due to their biocompatibility and suitability as multimodal imaging probes, CaF2: Ce, Gd, Nd NPs exhibit great potential as a traceable imaging agent in biomedical applications.