High X-ray Absorption Coefficient Research Articles

Role of Gold Nanoparticles in Drug Delivery

Recent developments in nanotechnology offer a multitude of approaches for investigating and tracking diverse biological and medical processes at the nanoscale. Nanoparticles can deliver medications directly to cancer cells, aiding in the diagnosis and treatment of diseases like cancer. Gold nanoparticles (AuNPs) are incredibly small gold particles, usually fewer than 100 nanometers in size. They are measured in nanometers. AuNPs are one type of nanoparticle that has shown promise as a medication delivery platform. Their outstanding stability, adjustable chemical and physical characteristics, and biocompatibility make them incredibly beneficial for drug delivery applications. The physical and chemical features of AuNPs' natural characteristics were studied. Localized surface plasmon resonance (LSPR), radioactivity, and a high X-ray absorption coefficient are among the physical characteristics of AuNPs that are commonly used in diagnosis and treatment. Compared to many other nanoparticles, AuNPs can create stable chemical interactions with groups that contain S and N. As a result, AuNPs can bind to a broad range of chemical ligands or polymers used for particular purposes. According to recent research, AuNPs can be easily modified to allow the delivery of pharmaceutical drugs directly to the target tissue. This article provides a brief overview of the more effective synthesis method for AuNPs and how they can be utilized as drug carriers to improve precision medicine.

Sr-Doping All-Inorganic CsPbBr3 Perovskite Thick Film for Self-Powered X-ray Detectors.

The all-inorganic perovskite cesium lead bromine (CsPbBr3) has attracted much attention in the field of X-ray detectors because of its high X-ray absorption coefficient, high carrier collection efficiency, and easy solution preparation. The low-cost anti-solvent method is the main method to prepare CsPbBr3; during this process, solvent volatilization will bring a large number of holes to the film, leading to the increase of defects. Based on the heteroatomic doping strategy, we propose that Pb2+ should be partially replaced by Sr2+ to prepare leadless all-inorganic perovskite. The introduction of Sr2+ promoted the ordered growth of CsPbBr3 in the vertical direction, increased the density and uniformity of the thick film, and achieved the goal of CsPbBr3 thick film repairing. In addition, the prepared CsPbBr3 and CsPbBr3:Sr X-ray detectors were self-powered without external bias, maintaining a stable response during on and off states at different X-ray dose rates. Furthermore, the detector base on 160 µm CsPbBr3:Sr had a sensitivity of 517.02 µC Gyair-1 cm-3 at zero bias under the dose rate of 0.955 µGy ms-1 and it obtained a fast response speed of 0.053-0.148 s. Our work provides a new opportunity to produce cost-effective and highly efficient self-powered perovskite X-ray detectors in a sustainable way.

Wafer-Scale Photolithography-Pixeled Pb-Free Perovskite X-ray Detectors.

Pb-free perovskite material is considered to be a promising material utilized in next-generation X-ray detectors due to its high X-ray absorption coefficient, decent carrier transport properties, and relatively low toxicity. However, the pixelation of the perovskite material with an industry-level photolithography processing method remains challenging due to its poor structural stability. Herein, we use Cs2AgBiBr6 perovskite material as the prototype and investigate its interaction with photolithographic polar solvents. Inspired by that, we propose a wafer-scale photolithography patterning method, where the pixeled perovskite array devices for X-ray detection are successfully prepared. The devices based on pixeled Pb-free perovskite material show a high detection sensitivity up to 19118 ± 763 μC Gyair-1 cm-2, which is comparable to devices with Pb-based perovskite materials and superior to the detection sensitivity (∼20 μC Gyair-1 cm-2) of the commercial a-Se detector. After pixelation, the devices achieve an improved spatial resolution capacity with the spatial frequency from 2.7 to 7.8 lp mm-1 at modulation-transfer-function (MTF) = 0.2. Thus, this work may contribute to the development of high-performance array X-ray detectors based on Cs2AgBiBr6 perovskite material.

Ultralow Detection Limit and Robust Hard X-ray Imaging Detector Based on Inch-Sized Lead-Free Perovskite Cs3Bi2Br9 Single Crystals.

Halide perovskites are promising candidates for soft X-ray detection (<80 keV) owing to their high X-ray absorption coefficient, resistivity, and mobility lifetime product. However, the lack of large high-quality single crystals (SCs) renders it challenging to manufacture robust hard X-ray imaging systems (>100 keV) with a low detection limit and stable dark current. Herein, high-quality inch-size two-dimensional (2D) Cs3Bi2Br9 (CBB) single crystals are grown from a melt via the Bridgman method. The crystal quality is enhanced by eliminating inclusions of CsBr-rich phases and restraining the trap-state density, leading to an enhanced resistivity of 1.41 × 1012 Ω cm and a mobility lifetime product of 8.32 × 10-4 cm2 V-1. The Au/CBB/Au single-crystal device exhibits a high sensitivity of 1705 μC Gyair-1 cm-2 in all-inorganic bismuth-based perovskites and an ultralow detection limit of 0.58 nGyair s-1 in all of the bismuth-based perovskites for 120 keV hard X-ray detection. The CBB detector exhibits high work stability with an ultralow dark current drift of 2.8 × 10-10 nA cm-1 s-1 V-1 and long-term air environment reliability under a high electric field of 10 000 V cm-1 owing to the ultrahigh ionic activation energy of the 2D structure. The proposed robust imaging system based on CBB SC is a promising tool for X-ray medical imaging and diagnostics.

Band Gap Engineering in β-Ga2O3 for a High-Performance X-ray Detector

Gallium oxide (Ga2O3) attracts great attention in the field of X-ray detection because of its ultrawide band gap, high breakdown electric field, and high X-ray absorption coefficient. However, unintentionally doped Ga2O3 tends to have low resistivity because of the shallow donors provided by unintentionally doped impurity elements or intrinsic defects. Iron and magnesium ion doping can increase the resistivity of β-Ga2O3, but the carrier drift length and carrier collection efficiency are greatly reduced because of the introduction of deep-level impurities. Here, Al-doped β-Ga2O3 (β-Ga2O3:Al) single crystals with high resistivity are obtained through band gap engineering. The mechanism by which Al3+ doping can increase the resistivity of the β-Ga2O3 crystal is discussed. A β-Ga2O3:15%Al-based X-ray detector with high resistivity and quality is prepared. The detector demonstrates a high sensitivity of 851.6 μC Gyair–1 cm–2, which is 42 times higher than that of the commercial amorphous Se X-ray detector. Furthermore, the detector exhibits a fast response speed and both rise time and decay time of less than 0.05 s. The high performance of the detector is attributed to the high resistivity and high quality of the crystal. This work presents a method to obtain high-performance X-ray detectors based on β-Ga2O3 single crystals through band gap engineering.

NIR-driven intracellular photocatalytic oxygen-supply on metallic molybdenum carbide@N-carbon for hypoxic tumor therapy

The intracellular O2-supply not only can relieve tumor hypoxia but also enhance the effects of photodynamic therapy (PDT). In this work, metallic Mo2C@N-carbon@PEG nanoparticles were constructed to reveal the near infrared (NIR)-photocatalytic O2 generation and promote photodynamic therapy (PDT). Here, (NH4)6Mo7O24·4H2O nanorods and urea were adopted as resources that were calcined to obtain Mo2C@N-carbon nanoparticles (20 nm). All samples displayed high NIR absorption as well as photothermal conversion efficiency of up to 52.7 % (Mo2C@N-Carbon-3@PEG). The density functional theory calculations demonstrated the metallic characteristic of Mo2C and that the consecutive interband/intraband charge-transition was responsible for the high NIR harvest and redox ability of electron-hole pairs, making the NIR-photocatalytic O2 and reactive oxygen species (ROS) generation. In comparison with the pure Mo2C, the heterostructure displayed twice the performance due to the enhanced charge-segregation between Mo2C and N-carbon. Given the high X-ray absorption coefficient and photothermal ability, the nanocomposite could be used in novel computer tomography and photothermal imaging contrast. Furthermore, the novel biodegradation and metabolism behaviors of nanocomposites were investigated, which were reflected as elimination from the body (mouse) via feces and urine within 14 days. The as-synthesized Mo2C@N-Carbon@PEG nanocomposites integrated the dual-model imaging, intracellular O2-supply, and phototherapy into one nanoplatform, revealing its potential for anti-cancer therapy.

Halide-modulated self-assembly of metal-free perovskite single crystals for bio-friendly X-ray detection

Halide-modulated self-assembly of metal-free perovskite single crystals for bio-friendly X-ray detection

Synthesis of 131I Iopamidol as a Tracer for Development of Iopamidol CT-Scan Contrast Agent

Computed Tomography (CT) Scan is a means of imaging/diagnostic method which is preferable in hospitals in terms of availability, efficiency and cost. Currently, CT contrast agent most widely used is the iodinated derivatives, due to its high X-ray absorption coefficient. Contrast agent is a medical preparation used in CT-scan modality which has capability of enhancing the performance of CT-scan to differentiate between target organs and surrounding tissues, and one of them is iopamidol. Development of iopamidol contrast agent requires several steps, i.e formulation, characterization, in-vitro and in-vivo tests prior to clinical study. To do in vivo study or biodistribution study in experimental animals, a radioactive iopamidol should be used to trace the compound throughout the body to predict its pharmacokinetics, and for that purpose a radioiodine (Iodium-131 or 131I) labeled iopamidol will be used. Optimation in the synthesis of 131I iopamidol was carried out by varying pH, temperature and reaction time to obtain 131I iopamidol with high radiochemical purity of more than 90% as a requirement of radiopharmaceutical preparation. The radiolabeled product was characterized using HPLC and the labeling efficiency was measured by TLC. The optimum condition obtained was repeated 3 times and the product was tested for stability in room temperature. Characterization using HPLC showed that retention time (Rt) of radiolabeled iopamidol was close to that of native iopamidol at ∼ 6 min, indicating that 131I iopamidol was already formed. Iodium-131 labeled iopamidol has been successfully synthesized with labeling efficiency or radiochemical purity of 96% ± 1%, and the optimum condition of 131I iopamidol reaction was obtained at pH 9, temperature of 140°C in 5 minutes reaction time, and the product was stable in room temperature up to 7 days. It is concluded that radioiodinated iopamidol has been successfully synthesized and will be used in the formulation of iopamidol as a part of iopamidol contrast agent development for CT-Scan purpose.

The Basic Properties of Gold Nanoparticles and their Applications in Tumor Diagnosis and Treatment.

Gold nanoparticles (AuNPs) have been widely studied and applied in the field of tumor diagnosis and treatment because of their special fundamental properties. In order to make AuNPs more suitable for tumor diagnosis and treatment, their natural properties and the interrelationships between these properties should be systematically and profoundly understood. The natural properties of AuNPs were discussed from two aspects: physical and chemical. Among the physical properties of AuNPs, localized surface plasmon resonance (LSPR), radioactivity and high X-ray absorption coefficient are widely used in the diagnosis and treatment of tumors. As an advantage over many other nanoparticles in chemicals, AuNPs can form stable chemical bonds with S-and N-containing groups. This allows AuNPs to attach to a wide variety of organic ligands or polymers with a specific function. These surface modifications endow AuNPs with outstanding biocompatibility, targeting and drug delivery capabilities. In this review, we systematically summarized the physicochemical properties of AuNPs and their intrinsic relationships. Then the latest research advancements and the developments of basic research and clinical trials using these properties are summarized. Further, the difficulties to be overcome and possible solutions in the process from basic laboratory research to clinical application are discussed. Finally, the possibility of applying the results to clinical trials was estimated. We hope to provide a reference for peer researchers to better utilize the excellent physicochemical properties of gold nanoparticles in oncotherapy.

Biomineralized Bimetallic Oxide Nanotheranostics for Multimodal Imaging-Guided Combination Therapy

The hypoxia of the tumor microenvironment (TME) often hinders the effectiveness of cancer treatments, especially O2-dependent photodynamic therapy (PDT).Methods: An integrated iridium oxide (IrO2)-manganese dioxide (MnO2) nanotheranostic agent was fabricated through bovine serum albumin (BSA)-based biomineralization of Ir3+ and Mn2+. BSA was first covalently modified with chlorin e6 (Ce6), and used to fabricate multifunctional BSA-Ce6@IrO2/MnO2 nanoparticles (NPs) for computed X-ray tomography (CT) and photoacoustic (PA) imaging-guided PDT and photothermal (PTT) therapy of cancer. Extensive in vitro and in vivo studies were performed.Results: The theranostic agent produced can relieve tumor hypoxia by the decomposition of endogenous H2O2 in cancer cells to oxygen. The oxygen generated can be exploited for improved PDT. Paramagnetic Mn2+ released from the NPs in the acidic TME permits magnetic resonance imaging (MRI) to be performed. The exceptional photothermal conversion efficiency (65.3%) and high X-ray absorption coefficient of IrO2 further endow the NPs with the ability to be used in computed CT and PA imaging. Extensive antitumor studies demonstrated that the BSA-Ce6@IrO2/MnO2 nanoplatform inhibits cancer cell growth, particularly after combined PTT and PDT. Systematic in vivo biosafety evaluations confirmed the high biocompatibility of the nanoplatform.Conclusion: This work not only provides a novel strategy for designing albumin-based nanohybrids for theranostic applications but also provides a facile approach for extending the biomedical applications of iridium-based materials.

A biomimetic one-pot synthesis of versatile Bi2S3/FeS2 theranostic nanohybrids for tumor-targeted photothermal therapy guided by CT/MR dual-modal imaging

Constructing versatile theranostic nanoplatforms that combine diagnostic and therapeutic moieties has shown great promise in the area of precision nanomedicine. However, the limitations on biosecurity, efficiency, and accessibility still need to be addressed. Herein, Bi2S3/FeS2 nanohybrids (NHs) were fabricated by a facile and biomimetic one-pot strategy using bovine serum albumin (BSA) as both the sulfur provider to achieve the nucleation and reaction nanocages to regulate the growth of NHs. Upon modification with folic acid (FA), the final obtained Bi2S3/FeS2@BSA-FA NHs could successfully target folate receptor α overexpressed 4T1 tumor cells. Moreover, CCK-8 assay and histopathologic evaluation confirmed the favorable biocompatibility of Bi2S3/FeS2@BSA-FA NHs, which is the premise of subsequent research. In addition, both in vitro and in vivo tests demonstrated that the Bi2S3/FeS2@BSA-FA NHs can serve as computed tomography (CT)/magnetic resonance (MR) dual mode imaging contrast agents, which possess a high X-ray absorption coefficient of 8.02 HU mM−1 and transverse relaxivity (53.9 mM−1s−1). And these two clinical imaging modes could complement each other. After intravenous injection, Bi2S3/FeS2@BSA-FA NHs exhibited efficient tumor homing, as shown by imaging and biodistribution measurement. Notably, when irradiated with 808 nm NIR laser (1.5 W.cm−2), the tumor growth of Bi2S3/FeS2@BSA-FA-treated group could be suppressed effectively, proving the high efficacy of photothermal therapy with these NHs. Thus, our research represents a facile and “green” approach for the construction of multifunctional theranostic reagents.

BSA-IrO2 : Catalase-like Nanoparticles with High Photothermal Conversion Efficiency and a High X-ray Absorption Coefficient for Anti-inflammation and Antitumor Theranostics.

Intrinsically integrating precise diagnosis, effective therapy, and self-anti-inflammatory action into a single nanoparticle is attractive for tumor treatment and future clinical application, but still remains a great challenge. In this study, bovine serum albumin-iridium oxide nanoparticles (BSA-IrO2 NPs) with extraordinary photothermal conversion efficiency, good photocatalytic activity, and a high X-ray absorption coefficient were prepared through one-step biomineralization. The nanoparticles allow tumor phototherapy and simultaneous photoacoustic/thermal imaging and computed tomography. More importantly, BSA-IrO2 NPs can also act as a catalase to protect normal cells against H2 O2 -induced reactive oxygen pressure and inflammation while significantly enhancing photoacoustic imaging through microbubble-based inertial cavitation. These remarkable features may open up the exploration iridium-based nanomaterials in theranostics.

Design and structural investigations of Yb3+ substituted β-Ca3(PO4)2 contrast agents for bimodal NIR luminescence and X-ray CT imaging

The quest for the development of bone substitutes with contrast agents for diagnostic imaging subsists to distinguish synthetic bone from native human tissue. To this aim, ytterbium (Yb3+) substitutions in β-tricalcium phosphate (β-Ca3(PO4)2, β-TCP) as contrast agents has been developed to differentiate implant materials thereby, facilitating as host for bimodal imaging application by means of NIR luminescence and X-ray computed tomography techniques. A facile aqueous chemical precipitation route with the aid of surfactant is used for the synthesis of Yb3+ substitutions in β-Ca3(PO4)2. The characterization results affirms the ability of β-Ca3(PO4)2 to host 4.36 mol% of Yb3+ while the excess Yb3+ crystallizes as YbPO4. The structure refinement results favour the occupancy of Yb3+ at the Ca2+(5) site of β-Ca3(PO4)2. The absorption and photoluminescence spectra in the near infrared region with emission intensity ~1024 nm in the second biological window correspond to 2F5/2 → 2F7/2 transitions of Yb3+. The designed Yb3+ substituted β-Ca3(PO4)2 does not exhibit any toxicity in human osteosarcoma cell lines and delivers an excellent in vitro CT contrast ability allied by the enhanced signal intensity and high X-ray absorption coefficient.

Upconversion optical/magnetic resonance imaging-guided small tumor detection and invivo tri-modal bioimaging based on high-performance luminescent nanorods.

In this work, we demonstrated multifunctional NaYbF4: Tm3+/Gd3+ upconversion (UC) nanorods (UCNRs) with near-infrared (NIR)-to-NIR emission and controlled phase and size for UC optical and T1/T2 dual-weighted magnetic resonance (MR) imaging-guided small tumor detection and tri-modal bioimaging. Cell toxicity and post-injection histology results revealed that our designed UCNRs present low biotoxicity and good biocompatibility in living animals. Real-time tracking based on UCNRs in living mice demonstrated that the UCNRs were mainly accumulated in the reticuloendothelial system (RES) and excreted through the hepatic pathway. Additionally, the UCNRs exhibited high X-ray absorption coefficient and large K-edge value, resulting in efficient invivo CT imaging. A new type of binary (Yb3+/Gd3+) MR contrast agent for simultaneous T1/T2 dual-weighted MR imaging was achieved by doping Gd3+ into NaYbF4 host. Importantly, a small tumor (5mm in diameter) could be detected invivo by intravenously injecting UCNRs under UC optical and MR imaging modalities. Therefore, these multifunctional nanoprobes based on NaYbF4:Tm3+/Gd3+ UCNRs with remarkable NIR-to-NIR emission provide potential applications for tri-modal UC optical, CT, binary T1/T2 MR imaging, and early-stage tumor detection in nanomedicine.

Mechanically stable tantalum coating on a nano-roughened NiTi stent for enhanced radiopacity and biocompatibility

Mechanically stable tantalum (Ta) coatings were deposited onto nano-roughened and Ta-incorporated nickel-titanium (NiTi) alloy substrates to enhance their radiopacity and biocompatibility. A target-ion induced plasma sputtering process was used to induce highly uniform nanoscale roughness on the NiTi alloys, with Ta implantation. Characterization by field-emission scanning electron microscopy, X-ray diffraction, and transmission electron microscopy revealed that a dense alpha-phase Ta coating layer was tightly anchored to the NiTi substrate via the nano-roughened interface structures. The mechanical stability and stretchability of the Ta coating was examined using scratch and tensile tests, respectively. The adhesion strength and mechanical stability of the Ta coating on the nano-roughened NiTi surface showed remarkable improvement compared with the Ta coating on a flat NiTi surface. X-ray microscopic images showed that the radiopacity of a NiTi stent was enhanced by the Ta coating layer because of its high X-ray absorption coefficient and large thickness. In vitro cell adhesion and MTS assay revealed that the Ta coating was beneficial for endothelial cell attachment and proliferation. These results demonstrate that the Ta coating deposited onto nano-roughened NiTi substantially improved the mechanical stability, radiopacity, and biocompatibility of the NiTi stent.

Development of biodegradable occlusion device using ductile magnesium-zinc-calcium alloy

Development of biodegradable occlusion device using ductile magnesium-zinc-calcium alloy

Iodinated silica/porphyrin hybrid nanoparticles for X-ray computed tomography/fluorescence dual-modal imaging of tumors

Silica nanoparticles containing covalently linked iodine and a near-infrared (NIR) fluorescence dye, namely porphyrin, have been synthesized through a one-pot sol–gel reaction. These particles are called iodinated silica/porphyrin hybrid nanoparticles (ISP HNPs). The ISP HNPs have both high X-ray absorption coefficient and NIR fluorescence. The ISP HNPs modified with folic acid (FA) and polyethylene glycol (PEG), denoted as FA-PEG-ISP HNPs, enabled the successful visualization of tumors in mice by both X-ray computed tomography (CT) and fluorescence imaging (FI). Thus, the FA-PEG-ISP HNPs are useful as contrast agents or probes for CT/FI dual-modal imaging.

Theranostic self-assembly structure of gold nanoparticles for NIR photothermal therapy and X-Ray computed tomography imaging.

The controllable self-assembly of amphiphilic mixed polymers grafted gold nanoparitcles (AuNPs) leads to strong interparticle plasmonic coupling, which can be tuned to the near-infrared (NIR) region for enhanced photothermal therapy (PTT). In this study, an improved thiolation method was adopted for ATRP and ROP polymer to obtain amphiphilic brushes of PMEO2MA-SH and PCL-SH. By anchoring PCL-SH and PMEO2MA-SH onto the 14 nm AuNPs, a smart hybrid building block for self-assembly was obtained. Increasing the PCL/PMEO2MA chain ratio from 0.8:1, 2:1 and 3:1 to 7:1, the structure of gold assemblies (GAs) was observed to transfer from vesicle to large compound micelle (LCM). Contributed to the special dense packed structure of gold nanoparticles in LCM, the absorption spectrometry of gold nanoparticles drastically red-shifted from 520 nm to 830 nm, which endowed the GAs remarkable NIR photothermal conversion ability. In addition, gold has high X-ray absorption coefficient which qualifies gold nanomaterial a potential CT contrast agent Herein, we obtain a novel gold assembly structure which can be utilized as potential photothermal therapeutic and CT contrast agents. In vitro and In vivo studies testified the excellent treatment efficacy of optimum GAs as a PTT and CT contrast agent. In vitro degradation test, MTT assay and histology study indicated that GAs was a safe, low toxic reagent with good biodegradability. Therefore, the optimum GAs with strong NIR absorption and high X-ray absorption coefficient could be used as a theranostic agent and the formation of novel gold large compound micelle might offers a new theory foundation for engineering design and synthesis of polymer grafted AuNPs for biomedical applications.

ChemInform Abstract: Gold Nanoparticles as Computerized Tomography (CT) Contrast Agents

AbstractReview: 114 refs.

Near‐Infrared Fluorescent Silica‐Coated Gold Nanoparticle Clusters for X‐Ray Computed Tomography/Optical Dual Modal Imaging of the Lymphatic System

Lymph nodes (LNs) are often removed to prevent the spread of cancer because they are frequently the first site of metastases. However, the enucleation of LNs requires difficult operative techniques and lymphedema can result as a complication. Although lymphedema can be cured by anastomosis of a lymph vessel (LV) to a vein, the operative procedure is extremely difficult because LNs and LVs are too small and indistinct to be identified. Therefore, visualization of LNs and LVs is important. The combination of X-ray computed tomography (CT) and fluorescence imaging, CT/fluorescence dual modal imaging, enables the visualization of LNs and LVs before and during surgery. To accomplish this, near-infrared fluorescent silica-coated gold nanoparticle clusters (Au@SiO₂) with a high X-ray absorption coefficient are synthesized. Both fluorescence imaging and CT show that the Au@SiO₂ nanoparticles gradually accumulate in LNs through LVs. CT determines the location and size of the LNs and LVs without dissection, and fluorescence imaging facilitates their identification. The Au@SiO₂ nanoparticles have neither hepatotoxicity nor nephrotoxicity. The results demonstrate that CT/fluorescence dual modal imaging using Au@SiO₂ nanoparticles provides anatomical information, including the location and size of LNs and LVs for determining a surgery plan, and provides intraoperative visualization of LNs and LVs to facilitate the operation.