Large-Scale Synthesis of Bioinert Tantalum Oxide Nanoparticles for X-ray Computed Tomography Imaging and Bimodal Image-Guided Sentinel Lymph Node Mapping

Advancements in tantalum based nanoparticles for integrated imaging and photothermal therapy in cancer management

Tantalum-based nanoparticles (TaNPs) have emerged as promising tools in cancer management, owing to their unique properties that facilitate innovative imaging and photothermal therapy applications. This review provides a comprehensive overview of recent advancements in TaNPs, emphasizing their potential in oncology. Key features include excellent biocompatibility, efficient photothermal conversion, and the ability to integrate multifunctional capabilities, such as targeted drug delivery and enhanced imaging. Despite these advantages, challenges remain in establishing long-term biocompatibility, optimizing therapeutic efficacy through surface modifications, and advancing imaging techniques for real-time monitoring. Strategic approaches to address these challenges include surface modifications like PEGylation to improve biocompatibility, precise control over size and shape for effective photothermal therapy, and the development of biodegradable TaNPs for safe elimination from the body. Furthermore, integrating advanced imaging modalities-such as photoacoustic imaging, magnetic resonance imaging (MRI), and computed tomography (CT)-enable real-time tracking of TaNPs in vivo, which is crucial for clinical applications. Personalized medicine strategies that leverage biomarkers and genetic profiling also hold promise for tailoring TaNP-based therapies to individual patient profiles, thereby enhancing treatment efficacy and minimizing side effects. In conclusion, TaNPs represent a significant advancement in nanomedicine, poised to transform cancer treatment paradigms while expanding into various biomedical applications.

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.

Gram-Scale Synthesis of Renal-Clearable Tantalum Nanodots with High Water Solubility for Computed Tomography Imaging In Vivo

Tantalum (Ta) emerges as a promising element for advanced computed tomography (CT) imaging probes owing to its high X-ray attenuation coefficient and excellent biocompatibility. Nevertheless, the synthesis of renally clear Ta-based imaging probes through simple methods remains a significant challenge. Herein, we introduce a simple and gram-scale approach for the synthesis of renal-clearable Ta nanodots with high water solubility for CT imaging in vivo. The Ta nanodots, coordination polymers, are fabricated via coordination reactions involving Ta(OH)5, citric acid (CA), and hydrogen peroxide. The Ta nanodots exhibit an ultrasmall hydrodynamic diameter (2.8 nm), high water solubility (1.88 g/mL, 688 mg Ta/mL), superior X-ray absorption capacity, gram-scale production capability (>10 g in lab synthesis), renal-clearable ability, and good biocompatibility. The Ta nanodots possess superior CT imaging efficacy across diverse tube voltages, enabling highly sensitive gastrointestinal CT imaging, renal CT imaging, and CT angiography (CTA). Moreover, Ta nanodots maintain robust CT imaging capabilities even at high X-ray energies, and Ta nanodots-based spectral CT achieves metallic artifacts-minimized CTA. The proposed Ta nanodots present substantial potential as a potent CT imaging probe for diagnosing various diseases.

Testing a Nanoparticle Reagent for Imaging Mass Cytometry

Mass cytometry (MC), a powerful single-cell analysis technique, has limitations in detecting low-abundance biomarkers. Nanoparticle (NP) reagents offer the potential for enhancing sensitivity by carrying large numbers of heavy metal isotopes. Here, we report NP reporters for imaging mass cytometry (IMC) based on NaYF4:Yb3+/Er3+ NPs. A two-step ligand exchange was used to coat NP surfaces with either methoxy-PEG2K-neridronate (PEG-Ner) and/or poly(sulfobetaine methacrylate)-neridronate (PSBMA-Ner). Both modifications provided long-term colloidal stability in PBS buffer. IMC measurements on tonsil tissue showed that PSBMA-Ner or a 1:1 mixture of PSBMA-Ner + PEG-Ner effectively suppressed nonspecific binding (NSB) at 2 × 1010 NPs/mL, unlike PEG-Ner alone. However, breast cancer tissue samples showed increased NSB at titers above 2 × 1010 NPs/mL. Reduced NSB with mixed PEG-Ner and PSBMA-Ner coatings opens the door for using heterobifunctional PEGs for the development of NP conjugates with bioaffinity agents, enabling more sensitive and specific MC analyses.

SODL-IR-FISTA: sparse online dictionary learning with iterative reduction FISTA for cone-beam X-ray luminescence computed tomography

Cone beam X-ray luminescence computed tomography (CB-XLCT) is an emerging imaging technique with potential for early 3D tumor detection. However, the reconstruction challenge due to low light absorption and high scattering in tissues makes it a difficult inverse problem. In this study, the online dictionary learning (ODL) method, combined with iterative reduction FISTA (IR-FISTA), has been utilized to achieve high-quality reconstruction. Our method integrates IR-FISTA for efficient and accurate sparse coding, followed by an online stochastic approximation for dictionary updates, effectively capturing the sparse features inherent to the problem. Additionally, a re-sparse step is introduced to enhance the sparsity of the solution, making it better suited for CB-XLCT reconstruction. Numerical simulations and in vivo experiments were conducted to assess the performance of the method. The SODL-IR-FISTA achieved the smallest location error of 0.325 mm in in vivo experiments, which is 58% and 45% of the IVTCG-L 1 (0.562 mm) and OMP-L 0 (0.721 mm), respectively. Additionally, it has the highest DICE similarity coefficient, which is 0.748. The results demonstrate that our approach outperforms traditional methods in terms of localization precision, shape restoration, robustness, and practicality in live subjects.

SBL-LCGL: sparse Bayesian learning based on Laplace distribution for robust cone-beam x-ray luminescence computed tomography

Objective. To address the quality and accuracy issues in the distribution of nanophosphors (NPs) using Cone-beam x-ray luminescence computed tomography (CB-XLCT) by proposing a novel reconstruction strategy.Approach. This paper introduces a sparse Bayesian learning reconstruction method termed SBL-LCGL, which is grounded in the Lipschitz continuous gradient condition and the Laplace prior to overcome the ill-posed inverse problem inherent in CB-XLCT.Main results. The SBL-LCGL method has demonstrated its effectiveness in capturing the sparse features of NPs and mitigating the computational complexity associated with matrix inversion. Both numerical simulation andin vivoexperiments confirm that the method yields satisfactory imaging results regarding the position and shape of the targets.Significance. The advancements presented in this work are expected to enhance the clinical applicability of CB-XLCT, contributing to its broader adoption in medical imaging and diagnostics.

Functional hydrogels for hepatocellular carcinoma: therapy, imaging, and in vitro model

Hepatocellular carcinoma (HCC) is among the most common malignancies worldwide and is characterized by high rates of morbidity and mortality, posing a serious threat to human health. Interventional embolization therapy is the main treatment against middle- and late-stage liver cancer, but its efficacy is limited by the performance of embolism, hence the new embolic materials have provided hope to the inoperable patients. Especially, hydrogel materials with high embolization strength, appropriate viscosity, reliable security and multifunctionality are widely used as embolic materials, and can improve the efficacy of interventional therapy. In this review, we have described the status of research on hydrogels and challenges in the field of HCC therapy. First, various preparation methods of hydrogels through different cross-linking methods are introduced, then the functions of hydrogels related to HCC are summarized, including different HCC therapies, various imaging techniques, in vitro 3D models, and the shortcomings and prospects of the proposed applications are discussed in relation to HCC. We hope that this review is informative for readers interested in multifunctional hydrogels and will help researchers develop more novel embolic materials for interventional therapy of HCC.

Immunological nanomaterials to combat cancer metastasis

Metastasis causes greater than 90% of cancer-associated deaths, presenting huge challenges for detection and efficient treatment of cancer due to its high heterogeneity and widespread dissemination to various organs. Therefore, it is imperative to combat cancer metastasis, which is the key to achieving complete cancer eradication. Immunotherapy as a systemic approach has shown promising potential to combat metastasis. However, current clinical immunotherapies are not effective for all patients or all types of cancer metastases owing to insufficient immune responses. In recent years, immunological nanomaterials with intrinsic immunogenicity or immunomodulatory agents with efficient loading have been shown to enhance immune responses to eliminate metastasis. In this review, we would like to summarize various types of immunological nanomaterials against metastasis. Moreover, this review will summarize a series of immunological nanomaterial-mediated immunotherapy strategies to combat metastasis, including immunogenic cell death, regulation of chemokines and cytokines, improving the immunosuppressive tumour microenvironment, activation of the STING pathway, enhancing cytotoxic natural killer cell activity, enhancing antigen presentation of dendritic cells, and enhancing chimeric antigen receptor T cell therapy. Furthermore, the synergistic anti-metastasis strategies based on the combinational use of immunotherapy and other therapeutic modalities will also be introduced. In addition, the nanomaterial-mediated imaging techniques (e.g., optical imaging, magnetic resonance imaging, computed tomography, photoacoustic imaging, surface-enhanced Raman scattering, radionuclide imaging, etc.) for detecting metastasis and monitoring anti-metastasis efficacy are also summarized. Finally, the current challenges and future prospects of immunological nanomaterial-based anti-metastasis are also elucidated with the intention to accelerate its clinical translation.

Oxidation behavior and atomic structural transition of size-selected coalescence-resistant tantalum nanoclusters

Herein a series of size-selected TaN(N = 147, 309, 561, 923, 1415, 2057, 6525, 10 000, 20 000) clusters are generated using a gas-phase condensation cluster beam source equipped with a lateral time-of-flight mass-selector. Aberration-corrected scanning transmission electron microscopy (AC-STEM) imaging reveals good thermal stability of TaNclusters in this study. The oxidation-induced amorphization is observed from AC-STEM imaging and further demonstrated through x-ray photoelectron spectroscopy and energy-dispersive spectroscopy. The oxidized Ta predominantly exists in the +5 oxidation state and the maximum spontaneous oxidation depth of the Ta cluster is observed to be 5 nm under prolonged atmosphere exposure. Furthermore, the size-dependent sintering and crystallization processes of oxidized TaNclusters are observed with anin situheating technique, and eventually, ordered structures are restored. As the temperature reaches 1300 °C, a fraction of oxidized Ta309clusters exhibit decahedral and icosahedral structures. However, the five-fold symmetry structures are absent in larger clusters, instead, these clusters exhibit ordered structures resembling those of the crystalline Ta2O5films. Notably, the sintering and crystallization process occurs at temperatures significantly lower than the melting point of Ta and Ta2O5, and the ordered structures resulting from annealing remain well-preserved after six months of exposure to ambient conditions.

Controllable synthesis of barium carbonate nano- and microparticles for SPECT and CT imaging

The design and synthesis of nano- and microcarriers for preclinical and clinical imaging are highly attractive due to their unique features, for example, multimodal properties. However, broad translation of these carriers into clinical practice is postponed due to the unknown biological reactivity of the new components used for their synthesis. Here, we have developed microcarriers (∼2-3 μm) and  nanocarriers (<200 nm) made of barium carbonate (BaCO3) for multiple imaging applications in vivo. In general, barium in the developed carriers can be used for X-ray computed tomography, and the introduction of a diagnostic isotope (99mTc) into the BaCO3 structure enables in vivo visualization using single-photon emission computed tomography. The bioimaging has shown that the radiolabeled BaCO3 nano- and microcarriers had different biodistribution profiles and tumor accumulation efficiencies after intratumoral and intravenous injections. In particular, in the case of intratumoral injection, all the types of used carriers mostly remained in the tumors (>97%). For intravenous injection, BaCO3 microcarriers were mainly localized in the lung tissues. However, BaCO3 NPs were mainly accumulated in the liver. These results were supported by ex vivo fluorescence imaging, direct radiometry, and histological analysis. The BaCO3-based micro- and nanocarriers showed negligible in vivo toxicity towards major organs such as the heart, lungs, liver, kidneys, and spleen. This study provides a simple strategy for the design and fabrication of the BaCO3-based carriers for the development of dual bioimaging.

Microwave Encounters Ionic Liquid: Synergistic Mechanism, Synthesis and Emerging Applications

Progress in microwave (MW) energy application technology has stimulated remarkable advances in manufacturing and high-quality applications of ionic liquids (ILs) that are generally used as novel media in chemical engineering. This Review focuses on an emerging technology via the combination of MW energy and the usage of ILs, termed microwave-assisted ionic liquid (MAIL) technology. In comparison to conventional routes that rely on heat transfer through media, the contactless and unique MW heating exploits the electromagnetic wave-ions interactions to deliver energy to IL molecules, accelerating the process of material synthesis, catalytic reactions, and so on. In addition to the inherent advantages of ILs, including outstanding solubility, and well-tuned thermophysical properties, MAIL technology has exhibited great potential in process intensification to meet the requirement of efficient, economic chemical production. Here we start with an introduction to principles of MW heating, highlighting fundamental mechanisms of MW induced process intensification based on ILs. Next, the synergies of MW energy and ILs employed in materials synthesis, as well as their merits, are documented. The emerging applications of MAIL technologies are summarized in the next sections, involving tumor therapy, organic catalysis, separations, and bioconversions. Finally, the current challenges and future opportunities of this emerging technology are discussed.

Cationic tantalum oxide nanoparticle contrast agent for micro computed tomography reveals articular cartilage proteoglycan distribution and collagen architecture alterations

OBJECTIVE

Cationic tantalum oxide nanoparticles (Ta2O5-cNPs), as a newly introduced contrast agent for computed tomography of cartilage, offer quantitative evaluation of proteoglycan (PG) content and biomechanical properties. However, knowledge on the depth-wise impact of cartilage constituents on nanoparticle diffusion, particularly the influence of the collagen network, is lacking. In this study, we aim to establish the depth-dependent relationship between Ta2O5-cNP diffusion and cartilage constituents (PG content, collagen content and network architecture).

METHODS

Osteochondral samples (n = 30) were harvested from healthy equine stifle joints (N = 15) and the diffusion of 2.55 nm diameter cationic Ta2O5-cNPs into the cartilage was followed with micro computed tomography (µCT) imaging for up to 96 hours. The diffusion-related parameters, Ta2O5-cNP maximum partition (Pmax) and diffusion time constant, were compared against biomechanical and depth-wise structural properties. Biomechanics were assessed using stress-relaxation and sinusoidal loading protocols, whereas PG content, collagen content and collagen network architecture were determined using digital densitometry, Fourier-transform infrared spectroscopy and polarized light microscopy, respectively.

RESULTS

The Pmax correlates with the depth-wise distribution of PGs (bulk Spearman's ρ = 0.87, p < 0.001). More open collagen network architecture at the superficial zone enhances intake of Ta2O5-cNPs, but collagen content overall decreases the intake. The Pmax values correlate with the equilibrium modulus (ρ = 0.80, p < 0.001) of articular cartilage.

CONCLUSION

This study establishes the feasibility of Ta2O5-cNPs for the precise and comprehensive identification of biomechanical and structural changes in articular cartilage via contrast-enhanced µCT.

Silicon-containing nanomedicine and biomaterials: materials chemistry, multi-dimensional design, and biomedical application

The invention of silica-based bioactive glass in the late 1960s has sparked significant interest in exploring a wide range of silicon-containing biomaterials from the macroscale to the nanoscale. Over the past few decades, these biomaterials have been extensively explored for their potential in diverse biomedical applications, considering their remarkable bioactivity, excellent biocompatibility, facile surface functionalization, controllable synthesis, etc. However, to expedite the clinical translation and the unexpected utilization of silicon-composed nanomedicine and biomaterials, it is highly desirable to achieve a thorough comprehension of their characteristics and biological effects from an overall perspective. In this review, we provide a comprehensive discussion on the state-of-the-art progress of silicon-composed biomaterials, including their classification, characteristics, fabrication methods, and versatile biomedical applications. Additionally, we highlight the multi-dimensional design of both pure and hybrid silicon-composed nanomedicine and biomaterials and their intrinsic biological effects and interactions with biological systems. Their extensive biomedical applications span from drug delivery and bioimaging to therapeutic interventions and regenerative medicine, showcasing the significance of their rational design and fabrication to meet specific requirements and optimize their theranostic performance. Additionally, we offer insights into the future prospects and potential challenges regarding silicon-composed nanomedicine and biomaterials. By shedding light on these exciting research advances, we aspire to foster further progress in the biomedical field and drive the development of innovative silicon-composed nanomedicine and biomaterials with transformative applications in biomedicine.

Advances in nanotechnology-based targeted-contrast agents for computed tomography and magnetic resonance

X-ray computed tomography (CT) and magnetic resonance (MR) imaging are essential tools in modern medical diagnosis and treatment. However, traditional contrast agents are inadequate in the diagnosis of various health conditions. Consequently, the development of targeted nano-contrast agents has become a crucial area of focus in the development of medical image-enhancing contrast agents. To fully understand the current development of nano-contrast agents, this review provides an overview of the preparation methods and research advancements in CT nano-contrast agents, MR nano-contrast agents, and CT/MR multimodal nano-contrast agents described in previous publications. Due to the physicochemical properties of nanomaterials, such as self-assembly and surface modifiability, these specific nano-contrast agents can greatly improve the targeting of lesions through various preparation methods and clearly highlight the distinction between lesions and normal tissues in both CT and MR. As a result, they have the potential to be used in the early stages of disease to improve diagnostic capacity and level in medical imaging.

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.

Bi-HPDO3A as a novel contrast agent for X-ray computed tomography

A new bismuth-based CT agent was synthesized through a facile synthesis strategy. The in vitro stability, toxicity and CT performance were evaluated. The in vivo imaging performance was investigated using three different doses (0.5, 1.2 and 5 mmol/kg) and the result obtained at 1.2 mmol/kg was compared with the clinically approved CT agent iopamidol at the same dosage.

Carbon Coated Iron-Cobalt Nanoparticles for Magnetic Particle Imaging

Magnetic particle imaging (MPI) is an emerging imaging modality that provides direct and quantitative mapping of iron oxide tracers. To achieve high sensitivity and good spatial resolution images, a magnetic nanoparticle with a higher contrast intensity needs to be developed. Currently, a majority of MPIs being developed for potential clinical application are composed of iron oxide nanoparticles with a spherical shape. In this project, we intend to report development of high-performance carbon (C) coated iron-cobalt (FeCo) nanoparticles (FeCo/C) and investigate their feasibility as a MPI agent. We have synthesized FeCo/C through a facile and simple method at mild temperature that is safe, easy, and up-scalable. We studied the structural and functional relationships and biocompatibility of this MPI agent in vitro. However, to enhance the aqueous solubility and biocompatibility, the surface of FeCo/C was modified with polyethylene glycol (PEG). We found that variation in the ratio of Fe and Co plays a vital role in their physical properties and functionality. In vitro imaging confirms that the Fe3Co1/C nanoparticle has highly competitive MPI intensity compared to VivoTrax, a commercially available MPI agent. Confocal laser scanning microscopy imaging with Rhodamine B labeled FeCo/C displays cellular internalization by the A375 cancer cells. The in vitro toxicity analysis concludes that there is no significant toxicity of FeCo/C nanoparticles. Therefore, the newly developed MPI agent holds strong promise for biomedical imaging and could be further validated in vivo in small animals.

Nanoceria as Safe Contrast Agents for X-ray CT Imaging

Cerium oxide nanoparticles (CeO2NPs) have exceptional catalytic properties, rendering them highly effective in removing excessive reactive oxygen species (ROS) from biological environments, which is crucial in safeguarding these environments against radiation-induced damage. Additionally, the Ce atom's high Z number makes it an ideal candidate for utilisation as an X-ray imaging contrast agent. We herein show how the injection of albumin-stabilised 5 nm CeO2NPs into mice revealed substantial enhancement in X-ray contrast, reaching up to a tenfold increase at significantly lower concentrations than commercial or other proposed contrast agents. Remarkably, these NPs exhibited prolonged residence time within the target organs. Thus, upon injection into the tail vein, they exhibited efficient uptake by the liver and spleen, with 85% of the injected dose (%ID) recovered after 7 days. In the case of intratumoral administration, 99% ID of CeO2NPs remained within the tumour throughout the 7-day observation period, allowing for observation of disease dynamics. Mass spectrometry (ICP-MS) elemental analysis confirmed X-ray CT imaging observations.

Sparse reconstruction based on dictionary learning and group structure strategy for cone-beam X-ray luminescence computed tomography

As a dual-modal imaging technology that has emerged in recent years, cone-beam X-ray luminescence computed tomography (CB-XLCT) has exhibited promise as a tool for the early three-dimensional detection of tumors in small animals. However, due to the challenges imposed by the low absorption and high scattering of light in tissues, the CB-XLCT reconstruction problem is a severely ill-conditioned inverse problem, rendering it difficult to obtain satisfactory reconstruction results. In this study, a strategy that utilizes dictionary learning and group structure (DLGS) is proposed to achieve satisfactory CB-XLCT reconstruction performance. The group structure is employed to account for the clustering of nanophosphors in specific regions within the organism, which can enhance the interrelation of elements in the same group. Furthermore, the dictionary learning strategy is implemented to effectively capture sparse features. The performance of the proposed method was evaluated through numerical simulations and in vivo experiments. The experimental results demonstrate that the proposed method achieves superior reconstruction performance in terms of location accuracy, target shape, robustness, dual-source resolution, and in vivo practicability.

Roles of MXenes in biomedical applications: recent developments and prospects

....With the development of nanomedical technology, the application of various novel nanomaterials in the biomedical field has been greatly developed in recent years. MXenes, which are new inorganic nanomaterials with ultrathin atomic thickness, consist of layered transition metal carbides and nitrides or carbonitrides and have the general structural formula Mn+1XnTx (n = 1-3). Based on the unique structural features of MXenes, such as ultrathin atomic thickness and high specific surface area, and their excellent physicochemical properties, such as high photothermal conversion efficiency and antibacterial properties, MXenes have been widely applied in the biomedical field. This review systematically summarizes the application of MXene-based materials in biomedicine. The first section is a brief summary of their synthesis methods and surface modification strategies, which is followed by a focused overview and analysis of MXenes applications in biosensors, diagnosis, therapy, antibacterial agents, and implants, among other areas. We also review two popular research areas: wearable devices and immunotherapy. Finally, the difficulties and research progress in the clinical translation of MXene-based materials in biomedical applications are briefly discussed.

Facile Synthesis and X-ray Attenuation Properties of Ultrasmall Platinum Nanoparticles Grafted with Three Types of Hydrophilic Polymers

Ultrasmall platinum nanoparticles (Pt-NPs) grafted with three types of hydrophilic and biocompatible polymers, i.e., poly(acrylic acid), poly(acrylic acid-co-maleic acid), and poly(methyl vinyl ether-alt-maleic acid) were synthesized using a one-pot polyol method. Their physicochemical and X-ray attenuation properties were characterized. All polymer-coated Pt-NPs had an average particle diameter (davg) of 2.0 nm. Polymers grafted onto Pt-NP surfaces exhibited excellent colloidal stability (i.e., no precipitation after synthesis for >1.5 years) and low cellular toxicity. The X-ray attenuation power of the polymer-coated Pt-NPs in aqueous media was stronger than that of the commercial iodine contrast agent Ultravist at the same atomic concentration and considerably stronger at the same number density, confirming their potential as computed tomography contrast agents.

Sustained intra-articular reactive oxygen species scavenging and alleviation of osteoarthritis by biocompatible amino-modified tantalum nanoparticles

Recent studies highlight the vital role of oxidative stress and reactive oxygen species (ROS) during progression of osteoarthritis (OA). Attenuating oxidative stress and reducing reactive oxygen species generation in joints represent reasonable strategies for the treatment of osteoarthritis. To address the potential question for clinical translation, and improve the biocompatibility and long-term performance of current antioxidants, the present study provided high biocompatible small positively charged tantalum nanoparticles (Ta-NH₂ NPs) with sustained intra-articular catalase activity and first applied to osteoarthritis intervention. Our in vitro results showed that Ta-NH₂ NPs were stable with good biocompatibility, and protected viability and hyaline-like phenotype in H₂O₂-challenged chondrocytes. In addition, the in vivo biodistribution data demonstrated a sustained retention of Ta-NH₂ NPs in the joint cavity, particularly in articular cartilage without organ toxicity and abnormality in hemogram or blood biochemistry indexes. Finally, compared with catalase (CAT), Ta-NH₂ NPs exhibited long-term therapeutic effect in monosodium iodoacetate (MIA) induced osteoarthritis model. This study preliminarily explored the potential of simply modified metal nanoparticles as effective reactive oxygen species scavenging agent for osteoarthritis intervention, and offered a novel strategy to achieve sustained reactive oxygen species suppression using biocompatible Ta-based nano-medicine in oxidative stress related diseases.

Noninvasive Gastrointestinal Tract Imaging Using BSA-Ag2Te Quantum Dots as a CT/NIR-II Fluorescence Dual-Modal Imaging Probe in Vivo

The combination of high-resolution computed tomography (CT) and the real-time sensitive second near-infrared window (NIR-II) fluorescence bioimaging can provide complementary information for the diagnosis, progression and prognosis of gastrointestinal disorders. Ag₂Te quantum dots (QDs) are a kind of promising CT/NIR-II fluorescence dual-modal imaging probe due to their high atomic number and narrow bandgap. However, conventional Ag₂Te QDs synthesized by oil phase approaches often suffer from complicated steps, harsh reaction conditions, and toxic organic solvents. Herein, we report the synthesis of bovine serum albumin (BSA)-Ag₂Te QDs using a biomineralization approach for CT/NIR-II fluorescence dual-modal imaging of the gastrointestinal tract. The BSA-Ag₂Te QDs are fabricated in a facile one-pot approach under mild conditions and exhibit homogeneous size, favorable monodispersity, admirable aqueous solubility, excellent X-ray attenuation properties, and outstanding NIR-II fluorescence performance. In vivo imaging experiments show that BSA-Ag₂Te QDs can be used in gastrointestinal tract CT/NIR-II dual-modal imaging with high spatiotemporal resolution and sensitivity. In addition, in an intestinal obstruction mouse model, accurate lesion positioning and imaging-guided obstruction relief surgery are successfully realized based on BSA-Ag₂Te QDs. Besides, BSA-Ag₂Te QDs have outstanding biocompatibility in vitro and in vivo. This study presents a high-performance and biosafe CT/NIR-II fluorescence dual-modal imaging probe for visualizing the gastrointestinal tract in vivo.

Spectral computed tomography with inorganic nanomaterials: State-of-the-art

Recently, spectral computed tomography (CT) technology has received great interest in the field of radiology. Spectral CT imaging utilizes the distinct, energy-dependent X-ray absorption properties of substances in order to provide additional imaging information. Dual-energy CT and multi-energy CT (Spectral CT) are capable of constructing monochromatic energy images, material separation images, energy spectrum curves, constructing effective atomic number maps, and more. However, poor contrast, due to neighboring X-ray attenuation of organs and tissues, is still a challenge to spectral CT. Hence, contrast agents (CAs) are applied for better differentiation of a given region of interest (ROI). Currently, many different kinds of inorganic nanoparticulate CAs for spectral CT have been developed due to the limitations of clinical iodine (I)-based contrast media, leading to the conclusion that inorganic nanomedicine applied to spectral CT will be a powerful collaboration both in basic research and in clinics. In this review, the underlying principles and types of spectral CT techniques are discussed, and some evolving clinical diagnosis applications of spectral CT techniques are introduced. In particular, recent developments in inorganic CAs used for spectral CT are summarized. Finally, the challenges and future developments of inorganic nanomedicine in spectral CT are briefly discussed.

Significance of Capping Agents of Colloidal Nanoparticles from the Perspective of Drug and Gene Delivery, Bioimaging, and Biosensing: An Insight

The over-growth and coagulation of nanoparticles is prevented using capping agents by the production of stearic effect that plays a pivotal role in stabilizing the interface. This strategy of coating the nanoparticles’ surface with capping agents is an emerging trend in assembling multipurpose nanoparticles that is beneficial for improving their physicochemical and biological behavior. The enhancement of reactivity and negligible toxicity is the outcome. In this review article, an attempt has been made to introduce the significance of different capping agents in the preparation of nanoparticles. Most importantly, we have highlighted the recent progress, existing roadblocks, and upcoming opportunities of using surface modified nanoparticles in nanomedicine from the drug and gene delivery, bioimaging, and biosensing perspectives.

Ytterbium Nanoparticle Contrast Agents for Conventional and Spectral Photon-Counting CT and Their Applications for Hydrogel Imaging

Significant work has been done to develop nanoparticle contrast agents for computed tomography (CT), with a focus on identifying safer and more effective formulations. Contrast agents for spectral photon-counting computed tomography (SPCCT), a fast-growing imaging modality derived from conventional CT, have also recently gained considerable attention. In this study, we explored the synthesis of ultrasmall ytterbium nanoparticles (YbNP) and demonstrated that, potentially, they can be used as conventional CT and SPCCT contrast agents. These nanoparticles were tested in vitro for their cytotoxicity and contrast-generating properties with a variety of imaging systems. When scanned with conventional CT and SPCCT at clinically relevant energies, YbNP are significantly more attenuating than gold nanoparticles (AuNP), the contrast agents that have been most well studied. Furthermore, YbNP were studied for their potential application for labeling and monitoring hydrogels. The presence of the YbNP payload in hydrogels allowed for hydrogel localization and tracking in vivo. Additionally, the in vivo imaging results revealed that YbNP generate higher contrast when compared to AuNP used as a label. In summary, this is the first research study to examine ultrasmall YbNP as conventional CT and SPCCT contrast agents, as well as using them in a hydrogel system to make it radiopaque. These findings underscore YbNP's utility as CT and SPCCT contrast agents, as well as their potential for tracking hydrogels in vivo.

Microenvironmental Behaviour of Nanotheranostic Systems for Controlled Oxidative Stress and Cancer Treatment

The development of smart, efficient and multifunctional material systems for diseases treatment are imperative to meet current and future health challenges. Nanomaterials with theranostic properties have offered a cost effective and efficient solution for disease treatment, particularly, metal/oxide based nanotheranostic systems already offering therapeutic and imaging capabilities for cancer treatment. Nanoparticles can selectively generate/scavenge ROS through intrinsic or external stimuli to augment/diminish oxidative stress. An efficient treatment requires higher oxidative stress/toxicity in malignant disease, with a minimal level in surrounding normal cells. The size, shape and surface properties of nanoparticles are critical parameters for achieving a theranostic function in the microenvironment. In the last decade, different strategies for the synthesis of biocompatible theranostic nanostructures have been introduced. The exhibition of therapeutics properties such as selective reactive oxygen species (ROS) scavenging, hyperthermia, antibacterial, antiviral, and imaging capabilities such as MRI, CT and fluorescence activity have been reported in a variety of developed nanosystems to combat cancer, neurodegenerative and emerging infectious diseases. In this review article, theranostic in vitro behaviour in relation to the size, shape and synthesis methods of widely researched and developed nanosystems (Au, Ag, MnOx, iron oxide, maghemite quantum flakes, La2O3-x, TaOx, cerium nanodots, ITO, MgO1-x) are presented. In particular, ROS-based properties of the nanostructures in the microenvironment for cancer therapy are discussed. The provided overview of the biological behaviour of reported metal-based nanostructures will help to conceptualise novel designs and synthesis strategies for the development of advanced nanotheranostic systems.

Hyaluronic acid-coated ultrasmall BiOI nanoparticles as a potentially targeted contrast agent for X-ray computed tomography

Commercial X-ray computed tomography (CT) contrast agents (CAs) are not appropriate for multicolor CT imaging and are limited due to a lack of tumor targeting. In this contribution, to favor the combination of high Z elements like bismuth and iodine for a broad range of X-ray photon energy, BiOI nanoparticles (NPs) are synthesized with hyaluronic acid (HA) coating to target the tumor cells with CD44 overexpression. The crystal structure of BiOI NPs is determined by X-ray powder diffraction, and the size of NPs is determined by a transmission electron microscope at about 14 ± 3 nm. The dynamic diameter of the NPs (DLS) in PBS buffer was measured at about 100 nm. Fourier transform infrared spectroscopy and thermal gravimetric analysis confirm the coating of BiOI NPs with HA. The stability of the NPs was also investigated via UV-vis spectroscopy. The immunocytochemistry process is performed to investigate the targeting ability of synthesized NPs on the human colon cancer cells with CD44 antigen. Finally, the X-ray attenuation of prepared HA-coated BiOI NPs is higher than Iohexol as the commercially available iodinated contrasting agent at the same concentrations, which can be administrated at much lower doses to achieve similar contrast to Iohexol.

Two-Stage Targeted Bismuthene-Based Composite Nanosystem for Multimodal Imaging Guided Enhanced Hyperthermia and Inhibition of Tumor Recurrence

A key challenge for nanomedicines in clinical application is to reduce the dose while achieving excellent efficacy, which has attracted extensive attention in dose toxicity and potential risks. It is thus necessary to reasonably design nanomedicine with high-efficiency targeting and accumulation. Here, we designed and synthesized a tetragonal bismuthene-based "all-in-one" composite nanosystem (TPP-Bi@PDA@CP) with two-stage targeting, multimodal imaging, photothermal therapy, and immune enhancement functions. Through the elaborate design of its structure, the composite nanosystem possesses multiple properties including (i) two-stage targeting function of hepatoma cells and mitochondria [the aggregation at the tumor site is 2.63-fold higher than that of traditional enhanced permeability and retention (EPR) effect]; (ii) computed tomography (CT) contrast-enhancement efficiency as high as ∼51.8 HU mL mg^-1 (3.16-fold that of the clinically available iopromide); (iii) ultrahigh photothermal conversion efficiency (52.3%, 808 nm), promising photothermal therapy (PTT), and high-contrast infrared thermal (IRT)/photoacoustic (PA) imaging of tumor; (iv) benefitting from the two-stage targeting function and excellent photothermal conversion ability, the dose used in this strategy is one of the lowest doses in hyperthermia (the inhibition rate of tumor cells was 50% at a dose of 15 μg mL^-1 and 75% at a dose of 25 μg mL^-1); (v) the compound polysaccharide (CP) shell with hepatoma cell targeting and immune enhancement functions effectively inhibited the recurrence of tumor. Therefore, our work reduces the dose toxicity and potential risk of nanomedicines and highlights the great potential as an all-in-one theranostic nanoplatform for two-stage targeting, integrated diagnostic imaging, photothermal therapy, and inhibition of tumor recurrence.

The future of early cancer detection

A proactive approach to detecting cancer at an early stage can make treatments more effective, with fewer side effects and improved long-term survival. However, as detection methods become increasingly sensitive, it can be difficult to distinguish inconsequential changes from lesions that will lead to life-threatening cancer. Progress relies on a detailed understanding of individualized risk, clear delineation of cancer development stages, a range of testing methods with optimal performance characteristics, and robust evaluation of the implications for individuals and society. In the future, advances in sensors, contrast agents, molecular methods, and artificial intelligence will help detect cancer-specific signals in real time. To reduce the burden of cancer on society, risk-based detection and prevention needs to be cost effective and widely accessible.

Recent advances and applications of microspheres and nanoparticles in transarterial chemoembolization for hepatocellular carcinoma

Transarterial chemoembolization (TACE) is a recommended treatment for patients suffering from intermediate and advanced hepatocellular carcinoma (HCC). As compared to the conventional TACE, drug-eluting bead TACE demonstrates several advantages in terms of survival, treatment response, and adverse effects. The selection of embolic agents is critical to the success of TACE. Many studies have been performed on the modification of the structure, size, homogeneity, biocompatibility, and biodegradability of embolic agents. Continuing efforts are focused on efficient loading of versatile chemotherapeutics, controlled sizes for sufficient occlusion, real-time detection intra- and post-procedure, and multimodality imaging-guided precise treatment. Here, we summarize recent advances and applications of microspheres and nanoparticles in TACE for HCC. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Small-Molecule Bi-DOTA Complex for High-Performance CT and Spectral CT Bioimaging

Objectives

It is necessary to develop a high-performance and biocompatible contrast agent to accurately diagnose various diseases via in vivo computed tomography (CT) imaging. Here, we synthesized a small molecular Bi-DOTA complex as a high-performance contrast agent for in vitro and in vivo CT bioimaging.

Materials and Methods

In our study, Bi-DOTA was fabricated through a facile and one-pot synthesis strategy. The formed Bi-DOTA complex was characterized via different techniques. Furthermore, Bi-DOTA was used for in vitro and in vivo CT bioimaging to verify its X-ray attenuation ability, especially in vivo kidney imaging, gastrointestinal tract CT imaging, and spectral CT imaging.

Results

A small molecular Bi-DOTA complex with a molecular mass of 0.61 kDa was synthesized successfully, which exhibited outstanding dispersion, good biocompatibility, and superior X-ray attenuation ability. Meanwhile, we showed that the obtained contrast agent was quite biocompatible and safe in the given concentration range as confirmed by in vitro and in vivo cytotoxicity assay. Also, the proposed contrast agent can be rapidly excreted from the body via the urinary system, avoiding the potential side effects caused by long-term retention in vivo. Importantly, Bi-DOTA was successfully used in high-quality in vitro CT imaging, in vivo kidney imaging, gastrointestinal tract CT imaging, and spectral CT imaging.

Conclusions

These superiorities allowed Bi-DOTA to be used as an efficient CT contrast agent and laid down a new way of designing high-performance CT contrast agents with great clinical transformation potential.

Highly sensitive and multiplexed mass spectrometric immunoassay techniques and clinical applications

Immunoassay is one of the most important clinical techniques for disease/pathological diagnosis. Mass spectrometry (MS) has been a popular and powerful readout technique for immunoassays, generating the mass spectrometric immunoassays (MSIAs) with unbeatable channels for multiplexed detection. The sensitivity of MSIAs has been greatly improved with the development of mass labels from element labels to small-molecular labels. MSIAs are also expended from the representative element MS-based methods to the laser-based organic MS and latest ambient MS, improving in both technology and methodology. Various MSIAs present high potential for clinical applications, including the biomarker screening, the immunohistochemistry, and the advanced single-cell analysis. Here, we give an overall review of the development of MSIAs in recent years, highlighting the latest improvement of mass labels and MS techniques for clinical immunoassays.

In Vivo Sol-Gel Reaction of Tantalum Alkoxide for Endovascular Embolization

Liquid embolic agents are considered the most promising for various embolization procedures because they enable deep penetration. For realizing effective procedures, the delivery of liquid embolic agents should be guided under X-ray imaging systems and the solidification time should be optimized for the specific indication. The biocompatibility of embolic agents is also crucial because they remain in the vessel after embolization. In this study, new biocompatible embolic agents based on tantalum ethoxide is synthesized. Tantalum alkoxide liquid embolics (TALE) possess the radiopacity for fluoroscopy and can control the penetration depth by modifying the sol-gel kinetics. Furthermore, TALE can serve as drug carriers for synergistic treatment. Using these excellent characteristics, it is demonstrated that TALE agents can be used in various situations including the transarterial chemoembolization of hepatocellular carcinoma and embolotherapy of massive bleeding from the femoral artery.

Noninvasive Visualization of Sub-5 mm Orthotopic Hepatic Tumors by a Nanoprobe-Mediated Positive and Reverse Contrast-Balanced Imaging Strategy

Delineation of small malignant lesions and their vasculature enables early and accurate diagnosis of hepatocellular carcinoma (HCC). However, it remains challenging to identify these features simultaneously by noninvasive imaging technology. Reverse contrast imaging emerges as a powerful means to detect early-stage HCC by taking inspiration from the intrinsic liver phagocytosis toward exogenous agents to generate negative tumor-to-normal tissue signals. However, this mechanism conflicts with the signal-enhancing requirements for vasculature visualization. Here, we solve this conundrum by designing a positive and reverse contrast-balanced imaging strategy based on a multifunctional PEG-Ta₂O₅@CuS nanoprobe that combines advanced gemstone spectral computer tomography (GSCT) with photoacoustic (PA) imaging. The nanoprobe exhibits preferential accumulation in Kupffer cells and hepatocytes over tumor cells, and its spectral properties are well matched with GSCT, leading to the enhancement of reverse contrast signals that enable clear delineation of 2-4 mm orthotopic HCC lesions. Meanwhile, its strong PA imaging capability at the second near-infrared (NIR-II) window makes vascular evaluation accessible by monitoring the positive signal enhancement derived from the limited tumor accumulation of the nanoprobe. In addition, the nanoprobe enables NIR-II photohyperthermia for timely tumor ablation. Overall, this proposed strategy shows potential in early detection and theranostics of HCC for improved clinical outcomes.

Development of nanotechnology-mediated precision radiotherapy for anti-metastasis and radioprotection

Radiotherapy (RT), including external beam RT and internal radiation therapy, uses high-energy ionizing radiation to kill tumor cells.

Tantalum Oxide Nanoparticles for the Quantitative Contrast-Enhanced Computed Tomography of Ex Vivo Human Cartilage: Assessment of Biochemical Composition and Biomechanics

Nanoparticle-based contrast agents, when used in concert with imaging modalities such as computed tomography (CT), enhance the visualization of tissues and boundary interfaces. However, the ability to determine the physiological state of the tissue via the quantitative assessment of biochemical or biomechanical properties remains elusive. We report the synthesis and characterization of tantalum oxide (Ta₂O₅) nanoparticle (NP) contrast agents for rapid, nondestructive, and quantitative contrast-enhanced computed tomography (CECT) to assess both the glycosaminoglycan (GAG) content and the biomechanical integrity of human metacarpal phalangeal joint (MCPJ) articular cartilage. Ta₂O₅ NPs 3-6 nm in diameter and coated with either nonionic poly(ethylene) glycol (PEG) or cationic trimethylammonium ligands readily diffuse into both healthy and osteoarthritic MCPJ cartilage. The CECT attenuation for the cationic and neutral NPs correlates with the glycosaminoglycan (GAG) content (R² = 0.8975, p < 0.05 and 0.7054, respectively) and the equilibrium modulus (R² = 0.8285, p < 0.05 and 0.9312, p < 0.05, respectively). The results highlight the importance of the surface charge and size in the design of NP agents for targeting and imaging articular cartilage. Further, nanoparticle CECT offers the visualization of both soft tissue and underlying bone unlike plain radiography, which is the standard for imaging bone in musculoskeletal diseases, and the ability to provide a real-time quantitative assessment of both hard and soft tissues to provide a comprehensive image of the disease stage, as demonstrated herein.

Innovations in lymph node targeting nanocarriers

Lymph nodes are secondary lymphoid tissues in the body that facilitate the co-mingling of immune cells to enable and regulate the adaptive immune response. They are also tissues implicated in a variety of diseases, including but not limited to malignancy. The ability to access lymph nodes is thus attractive for a variety of therapeutic and diagnostic applications. As nanotechnologies are now well established for their potential in translational biomedical applications, their high relevance to applications that involve lymph nodes is highlighted. Herein, established paradigms of nanocarrier design to enable delivery to lymph nodes are discussed, considering the unique lymph node tissue structure as well as lymphatic system physiology. The influence of delivery mechanism on how nanocarrier systems distribute to different compartments and cells that reside within lymph nodes is also elaborated. Finally, current advanced nanoparticle technologies that have been developed to enable lymph node delivery are discussed.

Intrinsically radiopaque biomaterial assortments: a short review on the physical principles, X-ray imageability, and state-of-the-art developments

X-ray attenuation ability, otherwise known as radiopacity of a material, could be indisputably tagged as the central and decisive parameter that produces contrast in an X-ray image. Radiopaque biomaterials are vital in the healthcare sector that helps clinicians to track them unambiguously during pre and post interventional radiological procedures. Medical imaging is one of the most powerful resources in the diagnostic sector that aids improved treatment outcomes for patients. Intrinsically radiopaque biomaterials enable themselves for visual targeting/positioning as well as to monitor their fate and further provide the radiologists with critical insights about the surgical site. Moreover, the emergence of advanced real-time imaging modalities is a boon to the contemporary healthcare systems that allow to perform minimally invasive surgical procedures and thereby reduce the healthcare costs and minimize patient trauma. X-ray based imaging is one such technologically upgraded diagnostic tool with many variants like digital X-ray, computed tomography, digital subtraction angiography, and fluoroscopy. In light of these facts, this review is aimed to briefly consolidate the physical principles of X-ray attenuation by a radiopaque material, measurement of radiopacity, classification of radiopaque biomaterials, and their recent advanced applications.

Notch Intracellular Domain Plasmid Delivery via Poly(Lactic-Co-Glycolic Acid) Nanoparticles to Upregulate Notch Pathway Molecules

Notch signaling is a highly conserved signaling system that is required for embryonic development and regeneration of organs. When the signal is lost, maldevelopment occurs and leads to a lethal state. Delivering exogenous genetic materials encoding Notch into cells can reestablish downstream signaling and rescue cellular functions. In this study, we utilized the negatively charged and FDA approved polymer poly(lactic-co-glycolic acid) to encapsulate Notch Intracellular Domain-containing plasmid in nanoparticles. We show that primary human umbilical vein endothelial cells (HUVECs) readily uptake the nanoparticles with and without specific antibody targets. We demonstrated that our nanoparticles are non-toxic, stable over time, and compatible with blood. We further demonstrated that HUVECs could be successfully transfected with these nanoparticles in static and dynamic environments. Lastly, we elucidated that these nanoparticles could upregulate the downstream genes of Notch signaling, indicating that the payload was viable and successfully altered the genetic downstream effects.

Folic Acid-Conjugated CuFeSe2 Nanoparticles for Targeted T2-Weighted Magnetic Resonance Imaging and Computed Tomography of Tumors In Vivo

Background

Development of new long-circulating contrast agents for computed tomography (CT) and magnetic resonance imaging (MRI) of different biological systems still remains a great challenge. Here, we report the synthesis of folic acid (FA)-targeted CuFeSe₂ nano-contrast agent for CT and MRI imaging in vitro and in vivo.

Methods and Results

In our study, CuFeSe₂ was fabricated through a facile and green aqueous reaction and then further aminated through silanization. The amine-functionalized CuFeSe₂-NH₂ nanoparticles enable the covalent conjugation of folate-conjugated polyethylene glycol (FA-PEG-COOH) as a targeting ligand onto their surface, which could improve the dispersion and endue the targetability of nanoparticles, respectively. The formed multifunctional CuFeSe₂-PEG-FA nanoparticles were characterized via different techniques, which exhibited outstanding dispersion, good biocompatibility and excellent FA-targeted capability. Meanwhile, the nanoparticles were quite safe in the given concentration range as confirmed by in vitro and in vivo toxicity assay. Importantly, CuFeSe₂-PEG-FA nanoparticles were successfully applied in CT/MRI dual-modality imaging in vitro and in vivo, which showed a better imaging performance and targeted capability.

Conclusion

Therefore, the constructed CuFeSe₂-PEG-FA nanoparticles have a great potential as an efficient contrast agent for dual-modality imaging of different biological systems.

Facile Fabrication of BiF3: Ln (Ln = Gd, Yb, Er)@PVP Nanoparticles for High-Efficiency Computed Tomography Imaging

X-ray computed tomography (CT) has been widely used in clinical practice, and contrast agents such as Iohexol are often used to enhance the contrast of CT imaging between normal and diseased tissue. However, such contrast agents can have some toxicity. Thus, new CT contrast agents are urgently needed. Owing to the high atomic number (Z = 83), low cost, good biological safety, and great X-ray attenuation property (5.74 cm² kg^-1 at 100 keV), bismuth has gained great interest from researchers in the field of nano-sized CT contrast agents. Here, we synthesized BiF₃: Ln@PVP nanoparticles (NPs) with an average particle size of about 380 nm. After coating them with polyvinylpyrrolidone (PVP), the BiF₃: Ln@PVP NPs possessed good stability and great biocompatibility. Meanwhile, compared with the clinical contrast agent Iohexol, BiF₃: Ln@PVP NPs showed superior in vitro CT imaging contrast. Subsequently, after in situ injection with BiF₃: Ln@PVP NPs, the CT value of the tumor site after the injection was significantly higher than that before the injection (the CT value of the pre-injection and post-injection was 48.9 HU and 194.58 HU, respectively). The morphology of the gastrointestinal (GI) tract can be clearly observed over time after oral administration of BiF₃: Ln@PVP NPs. Finally, the BiF₃: Ln@PVP NPs were completely discharged from the GI tract of mice within 48 h of oral administration with no obvious damage to the GI tract. In summary, our easily synthesized BiF₃: Ln@PVP NPs can be used as a potential clinical contrast agent and may have broad application prospects in CT imaging.

MXene and black phosphorus based 2D nanomaterials in bioimaging and biosensing: progress and perspectives

Bioimaging and biosensing have garnered interest in early cancer diagnosis due to the ability of gaining in-depth insights into cellular functions and providing a wide range of diagnostic parameters. Emerging 2D materials of multielement MXenes and monoelement black phosphorous nanosheets (BPNSs) with unique intrinsic physicochemical properties such as a tunable bandgap and layer-dependent fluorescence, high carrier mobility and transport anisotropy, efficient fluorescence quenching capability, desirable light absorption and thermoelastic properties, and excellent biocompatibility and biosafety properties provide promising nano-platforms for bioimaging and biosensing applications. In view of the growing attention on the rising stars of the post-graphene age in the progress of bioimaging and biosensing, and their common feature characteristics as well as complementarity for constructing complexes, the main objective of this review is to reveal the recent advances in the design of MXene or BPNS based nanoplatforms in the field of bioimaging and biosensing. The preparation and surface functionalization methods, biosafety, and other important aspects of bioimaging and biosensing applications of MXenes and BPNSs have been assessed systematically, along with highlighting the main challenges in further biomedical application. The review not only focuses on the advancements in 2D materials for use in bioimaging and biosensing but also assesses the possibility of their future potential in bioapplications.

Tantalum oxide nanoparticles as an advanced platform for cancer diagnostics: a review and perspective

The development of new safe and effective contrast agents (CAs) is a crucial factor to increase the effectiveness of computed tomography (CT). For now, tantalum oxide-based nanoparticles (TaOx NPs) are among the most promising CAs for CT due to their superior properties: high X-ray attenuation coefficient, excellent biocompatibility, and easily modifiable surface chemistry. Compared to the commercially available analogs (iodine-based CAs), TaOx NPs provide better contrast performance, long-circulation, and high safety profiles (reduced exposure of X-rays and CA dosage). Among the investigated nanoparticulate CAs they afford higher cost-effectiveness (Au, Pt, Lu). TaOx NPs can also be easily modified to include other imaging or therapeutic modalities. This review aims to summarize the current state-of-the-art knowledge in the field of tantalum oxide-based CAs used for single or multimodal imaging and theranostic purposes. The design specification of TaOx NPs in terms of size, surface functionalization, composition, and their influence on the contrast performance, toxicity, and pharmacokinetics are discussed. Finally, the future opportunities and challenges of TaOx NPs used as CT CAs are addressed.

Iodinated BSA Nanoparticles for Macrophage-Mediated CT Imaging and Repair of Gastritis

The development of a specific and noninvasive technology for understanding gastritic response together with efficient therapy is an urgent clinical issue. Herein, we fabricated a novel iodinated bovine serum albumin (BSA) nanoparticle based on gastritic microenvironment for computed tomography (CT) imaging and repair of acute gastritis. Derived from the characteristic mucosa defect and inflammatory cell (e.g., macrophage and neutrophil) infiltration in acute gastritis, the pH-sensitive nanoparticles can sedimentate under acidic conditions and be uniformly distributed in the defected mucosal via the phagocytosis of inflammatory cells. Hence, enhanced CT images can clearly reveal the mucosal morphology in the nanoparticle-treated gastritic rat over a long time window comparison with nanoparticle-treated healthy rats and clinical small-molecule-treated gastritic rat. In addition, we have discovered that nanoparticles can repair the atrophic gastric mucosa to a normal state. This repair process mainly stems from inflammatory immune response caused by phagocytized nanoparticles, such as the polarization of proinflammatory macrophages (M1) to anti-inflammatory macrophages (M2). The biocompatible nanoparticles that avoid the inherent defects of the clinical small molecules have great potential for accurate diagnosis and treatment of gastritis in the early stage.

Surfactant-free tantalum oxide nanoparticles: synthesis, colloidal properties, and application as a contrast agent for computed tomography

With the growing interest of the medical industry in biocompatible nanoparticles (NPs), the current synthetic methods should be adapted to appropriate demands (toxicity, scalability, etc.). Most applications require colloidal systems to be stable not only in water but also in vivo, which represents a major challenge. In this study, biocompatible Ta2O5 NPs were synthesized by a solvothermal method avoiding toxic reagents, and surfactant-free stable hydrosols were obtained and used for computed tomography (CT) imaging. The small hydrodynamic size (2 nm) and colloidal stability of primary NPs were studied by dynamic light scattering (DLS). The particles were characterized by X-ray diffraction, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and Brunauer-Emmett-Teller analysis to confirm their structure and purity. To develop a stable hydrosol preparation protocol, the influence of pH and ultrasonication duration on the stability of Ta2O5 sols was analyzed by DLS and microelectrophoresis. To enhance the understanding of NP behavior in vivo, sol stability in conditions close to physiological (NaCl solutions) was studied in a pH range of 3-9. Hydrosols prepared by the proposed protocol were stable for at least 6 months and exhibited negligible cytotoxicity. Ta2O5 NPs also showed high CT contrast both in theoretical calculations and in vivo (rat gastrointestinal tract).

Antifouling Strategies of Nanoparticles for Diagnostic and Therapeutic Application: A Systematic Review of the Literature

Nanoparticles (NPs) are promising platforms for the development of diagnostic and therapeutic tools. One of the main hurdle to their medical application and translation into the clinic is the fact that they accumulate in the spleen and liver due to opsonization and scavenging by the mononuclear phagocyte system. The “protein corona” controls the fate of NPs in vivo and becomes the interface with cells, influencing their physiological response like cellular uptake and targeting efficiency. For these reasons, the surface properties play a pivotal role in fouling and antifouling behavior of particles. Therefore, surface engineering of the nanocarriers is an extremely important issue for the design of useful diagnostic and therapeutic systems. In recent decades, a huge number of studies have proposed and developed different strategies to improve antifouling features and produce NPs as safe and performing as possible. However, it is not always easy to compare the various approaches and understand their advantages and disadvantages in terms of interaction with biological systems. Here, we propose a systematic study of literature with the aim of summarizing current knowledge on promising antifouling coatings to render NPs more biocompatible and performing for diagnostic and therapeutic purposes. Thirty-nine studies from 2009 were included and investigated. Our findings have shown that two main classes of non-fouling materials (i.e., pegylated and zwitterionic) are associated with NPs and their applications are discussed here highlighting pitfalls and challenges to develop biocompatible tools for diagnostic and therapeutic uses. In conclusion, although the complexity of biofouling strategies and the field is still young, the collective data selected in this review indicate that a careful tuning of surface moieties is a pivotal step to lead NPs through their future clinical applications.

One-Step, Rapid, 18F-19F Isotopic Exchange Radiolabeling of Difluoro-dioxaborinins: Substituent Effect on Stability and In Vivo Applications

The β-diketone moiety is commonly present in many anticancer drugs, antibiotics, and natural products. We describe a general method for radiolabeling β-diketone-bearing molecules with fluoride-18. Radiolabeling was carried out via 18F-19F isotopic exchange on nonradioactive difluoro-dioxaborinins, which were generated by minimally modifying the β-diketone as a difluoroborate. Radiochemistry was one-step, rapid (<10 min), and high-yielding (>80%) and proceeded at room temperature to accommodate the half-life of F-18 (t1/2 = 110 min). High molar activities (7.4 Ci/μmol) were achieved with relatively low starting activities (16.4 mCi). It was found that substituents affected both the solvolytic stability and fluorescence properties of difluoro-dioxaborinins. An F-18 radiolabeled difluoro-dioxaborinin probe that was simultaneously fluorescent showed sufficient stability for in vivo positron emission tomography (PET)/fluorescence imaging in mice, rabbits, and patients. These findings will guide the design of probes with specific PET/fluorescence properties; the development of new PET/fluorescence dual-modality reporters; and accurate in vivo tracking of β-diketone molecules.