Renal Clearable Ag Nanodots for in Vivo Computer Tomography Imaging and Photothermal Therapy

A Bilayer Polyurethane Patch with Sustained Growth Factor Release and Antibacteria for Re-epithelization of Large-Scale Oral Mucosal Defects

In the field of oral and maxillofacial surgery, extensive oral soft-tissue injuries occur repeatedly in clinical practice; however, effective restorative materials are lacking. In this study, a biodegradable waterborne polyurethane patch featuring a mucosa bionic bilayer structure is presented. This patch consists of a porous scaffold layer that faces the lesion, incorporating a polydopamine coating to achieve sustained release of epidermal growth factors (EGFs) for mucosal defect reconstruction. Additionally, there is a dense barrier layer toward the oral cavity loaded with silver nanoparticles, which prevents bacteria from entering the wound and simultaneously acts as a physical barrier. This patch can sustainably release EGF in vitro for 2 weeks, thereby facilitating the proliferation and migration of HaCaT and L929 cells, while effectively killing common oral cavity bacteria. In a rabbit buccal mucosal full-thickness defect model, the patch demonstrates better efficacy than the clinical benchmark, decellularized extracellular matrix (dECM). It effectively reduces wound inflammation and significantly upregulates gene expression associated with epithelialization by activating the EGF/epidermal growth factor receptor (EGFR) pathway. These mechanisms promote the proliferation, differentiation, and migration of epithelial/keratinocyte cells, ultimately expediting mucosal defect healing and wound closure.

A Smart Stimulation-Deadhesion and Antimicrobial Hydrogel for Repairing Diabetic Wounds Infected with Methicillin-Resistant Staphylococcus aureus

The healing of chronic diabetic wounds is a common and significant challenge in the medical field. Despite extensive efforts, the development of hydrogel dressings with satisfactory functionality remains an ongoing concern. In this study, a multifunctional hydrogel wound dressing (PAN/Ag-PLG) with adhesion, antibacterial, hemostatic, and other properties, which can effectively repair diabetic wounds infected with methicillin-resistant Staphylococcus aureus (MRSA), is presented. The hydrogel dressing is composed of gallic acid (GA)-functionalized polylysine (PL)-reduced silver nanoparticles (Ag-PLG), oxidized hyaluronic acid (OHA), and cross-linked polyacrylic acid grafted with N-hydrosuccinimide ester. Notably, compared to most conventional wound dressing that lack adhesion or are difficult to remove, the prepared hydrogels exhibit excellent adhesion and mild stimulation-triggered detachment. In vitro and in vivo experiments reveal that the PAN/Ag-PLG hydrogel exhibits outstanding biocompatibility and antibacterial properties and promotes diabetic wound repair by reducing oxidative damage and promoting cell migration and angiogenesis. The smart PAN/Ag-PLG hydrogel reported in this study provides an approach for the potential clinical development of painless antibacterial dressings.

Photothermal Superhydrophobic Cotton Fabric Based on Silver Nanoparticles Cross-Linked by Polydopamine and Polyethylenimide

Photothermal materials that can convert solar energy into heat energy through photothermal conversion have attracted extensive attention, but these materials are easily polluted by the environment. Here, we propose a simple and effective strategy for constructing photothermal superhydrophobic cotton fabrics with self-cleaning ability. The PDA@PEI@GA@Ag@PDMS-coated cotton fabric can achieve good superhydrophobicity (water contact angle: 159.6°) by a simple dipping method and mussel-inspired dopamine surface modification, which is regulated by the mass of dopamine, the mass of silver nitrate, and the concentration of polydimethylsiloxane (PDMS). The coated cotton fabric has good physical and chemical stability. Meanwhile, the coated cotton fabric has excellent self-cleaning and antifouling properties. The superhydrophobic PDA@PEI@GA@Ag@PDMS fabric exhibits excellent and stable photothermal properties, with the surface temperature reaching 70.4 °C under simulated sunlight with a current of 20 A. This photothermal superhydrophobic fabric with self-cleaning properties is expected to be applied in the field of photothermal conversion.

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.

Spectral computed tomography-guided radiotherapy of osteosarcoma utilizing BiOI nanosheets

As an aggressive malignant bone tumor, osteosarcoma (OS) is usually found in children and adolescents. Computed tomography (CT) is an important tool for the clinical evaluation of osteosarcoma, but limits to low diagnostic specificity due to single parameters of traditional CT and modest signal-to-noise ratio of clinical iodinated contrast agents. As one kind of spectral CT, dual-energy CT (DECT), with the advantage of a provision of multi-parameter information, makes it possible to acquire the best signal-to-noise ratio image, accurate detection, as well as imaging-guided therapy of bone tumors. Hereby, we synthesized BiOI nanosheets (BiOI NSs) as a DECT contrast agent with superior imaging capability compared to iodine agents for clinical detection of OS. Meanwhile, the synthesized BiOI NSs with great biocompatibility is able to achieve effective radiotherapy (RT) by enhancing X-ray dose deposition at the tumor site, leading to DNA damage, which in turn inhibits tumor growth. This study offers a promising new avenue for DECT imaging-guided treatment of OS. STATEMENT OF SIGNIFICANCE: Osteosarcoma (OS) is a common primary malignant bone tumor. Traditional surgical procedures and conventional CT scans are often used for the treatment and monitoring of OS, but the effects are generally unsatisfactory. In this work, BiOI nanosheets (NSs) was reported for dual-energy CT (DECT) imaging-guided OS radiotherapy. The powerful and constant X-ray absorption of BiOI NSs at any energy guarantees excellent enhanced DECT imaging performance, allowing detailed visualization of OS through images with a better signal-to-noise ratio and guiding radiotherapy process. The deposition of X-rays could be greatly enhanced by Bi atoms to induce serious DNA damage in radiotherapy. Taken together, the BiOI NSs for DECT-guided radiotherapy will greatly improve the current treatment status of OS.

Preparation of photothermal responsive, antibacterial hydrogel by using PVA-Alg and silver nanofibers as building blocks

Introduction: Photothermal responsive, antimicrobial hydrogels are very attractive and have great potential in the field of tissue engineering. The defective wound environment and metabolic abnormalities in diabetic skin would lead to bacterial infections. Therefore, multifunctional composites with antimicrobial properties are urgently needed to improve the current therapeutic outcomes of diabetic wounds. We prepared an injectable hydrogel loaded with silver nanofibers for efficient and sustained bactericidal activity. Methods: To construct this hydrogel with good antimicrobial activity, homogeneous silver nanofibers were first prepared by solvothermal method and then dispersed in PVA-lg solution. After homogeneous mixing and gelation, injectable hydrogels (Ag@H) wrapped with silver nanofibers were obtained. Results: By virtue of Ag nanofibers, Ag@H exhibited good photothermal conversion efficiency and good antibacterial activity against drug-resistant bacteria, while the in vivo antibacterial also showed excellent performance. The results of antibacterial experiments showed that Ag@H had significant bactericidal effects on MRSA and E. coli with 88.4% and 90.3% inhibition rates, respectively. Discussion: The above results indicate that Ag@H with photothermal reactivity and antibacterial activity is very promising for biomedical applications, such as wound healing and tissue engineering.

Challenges and advances for glioma therapy based on inorganic nanoparticles

Glioma is one of the most serious central nervous system diseases, with high mortality and poor prognosis. Despite the continuous development of existing treatment methods, the median survival time of glioma patients is still only 15 months. The main treatment difficulties are the invasive growth of glioma and the obstruction of the blood-brain barrier (BBB) to drugs. With rapid advancements in nanotechnology, inorganic nanoparticles (INPs) have shown favourable application prospects in the diagnosis and treatment of glioma. Due to their extraordinary intrinsic features, INPs can be easily fabricated, while doping with other elements and surface modification by biological ligands can be used to enhance BBB penetration, targeted delivery and biocompatibility. Guided glioma theranostics with INPs can improve and enhance the efficacy of traditional methods such as chemotherapy, radiotherapy and gene therapy. New strategies, such as immunotherapy, photothermal and photodynamic therapy, magnetic hyperthermia therapy, and multifunctional inorganic nanoplatforms, have also been facilitated by INPs. This review emphasizes the current state of research and clinical applications of INPs, including glioma targeting and BBB penetration enhancement methods, in vivo and in vitro biocompatibility, and diagnostic and treatment strategies. As such, it provides insights for the development of novel glioma treatment strategies.

Inorganic Nanomaterials Used in Anti-Cancer Therapies:Further Developments

In this article, we provide an overview of the progress of scientists working to improve the quality of life of cancer patients. Among the known methods, cancer treatment methods focusing on the synergistic action of nanoparticles and nanocomposites have been proposed and described. The application of composite systems will allow precise delivery of therapeutic agents to cancer cells without systemic toxicity. The nanosystems described could be used as a high-efficiency photothermal therapy system by exploiting the properties of the individual nanoparticle components, including their magnetic, photothermal, complex, and bioactive properties. By combining the advantages of the individual components, it is possible to obtain a product that would be effective in cancer treatment. The use of nanomaterials to produce both drug carriers and those active substances with a direct anti-cancer effect has been extensively discussed. In this section, attention is paid to metallic nanoparticles, metal oxides, magnetic nanoparticles, and others. The use of complex compounds in biomedicine is also described. A group of compounds showing significant potential in anti-cancer therapies are natural compounds, which have also been discussed.

Emerging ultrasmall luminescent nanoprobes for in vivo bioimaging

Photoluminescence (PL) imaging has become a fundamental tool in disease diagnosis, therapeutic evaluation, and surgical navigation applications. However, it remains a big challenge to engineer nanoprobes for high-efficiency in vivo imaging and clinical translation. Recent years have witnessed increasing research efforts devoted into engineering sub-10 nm ultrasmall nanoprobes for in vivo PL imaging, which offer the advantages of efficient body clearance, desired clinical translation potential, and high imaging signal-to-noise ratio. In this review, we present a comprehensive summary and contrastive discussion of emerging ultrasmall luminescent nanoprobes towards in vivo PL bioimaging of diseases. We first summarize size-dependent nano-bio interactions and imaging features, illustrating the unique attributes and advantages/disadvantages of ultrasmall nanoprobes differentiating them from molecular and large-sized probes. We also discuss general design methodologies and PL properties of emerging ultrasmall luminescent nanoprobes, which are established based on quantum dots, metal nanoclusters, lanthanide-doped nanoparticles, and silicon nanoparticles. Then, recent advances of ultrasmall luminescent nanoprobes are highlighted by surveying their latest in vivo PL imaging applications. Finally, we discuss existing challenges in this exciting field and propose some strategies to improve in vivo PL bioimaging and further propel their clinical applications.

A multi-enzyme-like activity exhibiting mussel-inspired nanozyme hydrogel for bacteria-infected wound healing

Bacterial infection, tissue hypoxia, and inflammatory and oxidative stress are several key problems in wound healing of chronic infections. Herein, a multi-enzyme-like activity exhibiting multifunctional hydrogel made up of mussel-inspired carbon dot reduced-Ag (CDs/AgNPs) and Cu/Fe-nitrogen-doped carbon (Cu,Fe-NC) was designed. Due to the loss of glutathione (GSH) and oxidase (OXD)-like activity of the nanozyme (decomposes O₂ to generate a superoxide anion radical (O₂˙^-) and hydroxyl radical production (˙OH)), the multifunctional hydrogel exhibited excellent antibacterial performance. More importantly, during the bacterial elimination within the inflammatory phase of wound healing, the hydrogel could act as a catalase (CAT)-like agent to supply adequate O₂ by catalyzing intracellular H₂O₂ for hypoxia abatement. The catechol groups on the CDs/AgNPs endowed them with the dynamic redox equilibrium properties of phenol-quinones, thus providing the hydrogel with mussel-like adhesion properties. The multifunctional hydrogel was shown to excellently promote bacterial infection wound healing and maximize the efficiency of nanozymes.

Polysaccharide-based hydrogel with photothermal effect for accelerating wound healing

Polysaccharide-based hydrogel has excellent biochemical function, abundant sources, good biocompatibility and other advantages, and has a broad application prospect in biomedical fields, especially in the field of wound healing. With its inherent high specificity and low invasive burden, photothermal therapy has shown great application prospect in preventing wound infection and promoting wound healing. Combining polysaccharide-based hydrogel with photothermal therapy (PTT), multifunctional hydrogel with photothermal, bactericidal, anti-inflammatory and tissue regeneration functions can be designed, so as to achieve better therapeutic effect. This review first focuses on the basic principles of hydrogel and PTT, and the types of polysaccharides that can be used to design hydrogels. In addition, according to the different materials that produce photothermal effects, the design considerations of several representative polysaccharide-based hydrogels are emphatically introduced. Finally, the challenges faced by polysaccharide-based hydrogels with photothermal properties are discussed, and the future prospects of this field are put forward.

Multifunctional Bi NSs@BSA Nanoplatform Guided by CT Imaging for Effective Photothermal Therapy

Photothermal therapy (PTT) has attracted great attention as an anticancer treatment strategy. With the rapid development of nanomedicine, multifunctional inorganic nanophotothermal agents provide a new way to improve the effect of PTT. Herein, bovine serum albumin (BSA)-modified Bi nanosheets (Bi NSs) with good biocompatibility were synthesized by a facile redox and ball milling method and applied as a photothermal agent for the enhancement of PTT. Owing to the strong near-infrared absorption, Bi NSs exhibit high photothermal conversion efficiency (η = 36.17%) under 808 nm laser irradiation and can serve as a nanotherapeutic agent for cancer therapy. In addition, in vitro cell safety analysis also suggests that the toxicity of BSA-modified Bi NSs is negligible. Upon 808 nm irradiation, the uptake ability of tumor cells to Bi NSs@BSA has been improved. Moreover, Bi NSs@BSA also can be used as a good contrast agent for CT imaging and then to observe the distribution of materials in the tumor site. Finally, Bi NSs@BSA-mediated PTT results show a high ablation rate of A549 tumor cells both in vitro and in vivo. All results reveal that Bi NSs@BSA is a promising nanotherapeutic platform for PTT.

Engineering of Near-Infrared-Activated Lignin-Polydopamine-Nanosilver Composites for Highly Efficient Sterilization

Photothermal synergistic antimicrobial therapy is considered a promising strategy to cope with antibiotic-resistant bacterial infections. In this work, lignin-based polydopamine nanosilver composites (LS-PDA-Ag) were engineered by a two-step process including self-assembly and microwave-assisted reduction. First, sodium lignosulfonate (LS) was not only used as a carrier to disperse polydopamine (PDA) and silver nanoparticles (AgNPs), but also used to reduce Ag+ for producing AgNPs. Second, PDA could promote the reduction of Ag+ and enhance the photothermal effect of AgNPs to further improve antibacterial efficiency. Finally, LS, AgNPs, and PDA complement each other, forming a synergistic photothermal antibacterial mechanism, achieving efficient bacterial killing within a short time. The antibacterial test of LS-PDA-Ag confirmed that 7.6 log10 CFU/mL of Escherichia coli were killed in 10 min under near-infrared irradiation. Furthermore, the LS-PDA-Ag can be blended with waterborne polyurethane to synthesize hybrid films, which also results in rapid sterilization and mechanical performance improvement. Considering the highly effective antibacterial activity of the LS-PDA-Ag composite, this work may provide perspectives on the design of green photothermal antibacterial materials.

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.

In situ self-assembly of polydopamine inside injectable hydrogels: antibacterial activity and photothermal therapy for superbug-infected wound healing

Ideal antibacterial hydrogel wound dressing triggered by the in situ self-assembly of the PDA NPs inside the gel.

Plasmonic Oxygen Defects in MO3- x (M = W or Mo) Nanomaterials: Synthesis, Modifications, and Biomedical Applications

Nanomedicine is a promising technology with many advantages and provides exciting opportunities for cancer diagnosis and therapy. During recent years, the newly developed oxygen-deficiency transition metal oxides MO_{3- x} (M = W or Mo) have received significant attention due to the unique optical properties, such as strong localized surface plasmon resonance (LSPR) , tunable and broad near-IR absorption, high photothermal conversion efficiency, and large X-ray attenuation coefficient. This review presents an overview of recent advances in the development of MO_{3- x} nanomaterials for biomedical applications. First, the fundamentals of the LSPR effect are introduced. Then, the preparation and modification methods of MO_{3- x} nanomaterials are summarized. In addition, the biological effects of MO_{3- x} nanomaterials are highlighted and their applications in the biomedical field are outlined. This includes imaging modalities, cancer treatment, and antibacterial capability. Finally, the prospects and challenges of MO_{3- x} and MO_{3- x} -based nanomaterial for fundamental studies and clinical applications are also discussed.

Inorganic nanomaterials with rapid clearance for biomedical applications

Inorganic nanomaterials that have inherently exceptional physicochemical properties (e.g., catalytic, optical, thermal, electrical, or magnetic performance) that can provide desirable functionality (e.g., drug delivery, diagnostics, imaging, or therapy) have considerable potential for application in the field of biomedicine. However, toxicity can be caused by the long-term, non-specific accumulation of these inorganic nanomaterials in healthy tissues, preventing their large-scale clinical utilization. Over the past several decades, the emergence of biodegradable and clearable inorganic nanomaterials has offered the potential to prevent such long-term toxicity. In addition, a comprehensive understanding of the design of such nanomaterials and their metabolic pathways within the body is essential for enabling the expansion of theranostic applications for various diseases and advancing clinical trials. Thus, it is of critical importance to develop biodegradable and clearable inorganic nanomaterials for biomedical applications. This review systematically summarizes the recent progress of biodegradable and clearable inorganic nanomaterials, particularly for application in cancer theranostics and other disease therapies. The future prospects and opportunities in this rapidly growing biomedical field are also discussed. We believe that this timely and comprehensive review will stimulate and guide additional in-depth studies in the area of inorganic nanomedicine, as rapid in vivo clearance and degradation is likely to be a prerequisite for the future clinical translation of inorganic nanomaterials with unique properties and functionality.

Ag@S-nitrosothiol core-shell nanoparticles for chemo and photothermal synergistic tumor targeted therapy

Along with the development of controlled delivery systems for targeted therapy, 'single-strategy' therapy often fails to achieve the desired performance in real body internal environments. In such a case, it is necessary to develop synergistic therapy strategies. Herein, for the first time, we designed and synthesized hyaluronic acid (HA) modified Ag@S-nitrosothiol core-shell nanoparticles for synergistic tumor cell targeted therapy based on photothermal therapy (PTT) and nitric oxide (NO) based chemotherapy. Triggered by near-infrared irradiation (NIR), the Ag core nanoparticle would convert the light to cytotoxic heat via a surface plasmon resonance mechanism for cancer cell apoptosis. Meanwhile, responding to NIR as well as the generated heat, the S-nitrosothiol polymeric shells would give off free NO at high concentration, inducing NO based chemotherapy. Tumor cell selective cytotoxicity assay in vitro as well as tumor bearing mouse experiments in vivo demonstrated the effective photothermal and NO based chemical synergistic tumor targeted therapy. This spatiotemporally controllable system could provide a new option and era for tumor targeted therapy in the future.

Multifunctional Theranostic Graphene Oxide Nanoflakes as MR Imaging Agents with Enhanced Photothermal and Radiosensitizing Properties

The integration of multiple therapeutic and diagnostic functions into a single nanoplatform for image-guided cancer therapy has been an emerging trend in nanomedicine. We show here that multifunctional theranostic nanostructures consisting of superparamagnetic iron oxide (SPIO) and gold nanoparticles (AuNPs) scaffolded within graphene oxide nanoflakes (GO-SPIO-Au NFs) can be used for dual photo/radiotherapy by virtue of the near-infrared (NIR) absorbance of GO for photothermal therapy (PTT) and the Z element radiosensitization of AuNPs for enhanced radiation therapy (RT). At the same time, this nanoplatform can also be detected by magnetic resonance (MR) imaging because of the presence of SPIO NPs. Using a mouse carcinoma model, GO-SPIO-Au NF-mediated combined PTT/RT exhibited a 1.85-fold and 1.44-fold higher therapeutic efficacy compared to either NF-mediated PTT or RT alone, respectively, resulting in a complete eradication of tumors. As a sensitive multifunctional theranostic platform, GO-SPIO-Au NFs appear to be a promising nanomaterial for enhanced cancer imaging and therapy.

Hetero-Core-Shell BiNS-Fe@Fe as a Potential Theranostic Nanoplatform for Multimodal Imaging-Guided Simultaneous Photothermal-Photodynamic and Chemodynamic Treatment

Photothermal/photodynamic therapy (PTT/PDT) and synergistic therapeutic strategies are often sought after, owing to their low side effects and minimal invasiveness compared to chemotherapy and surgical treatments. However, in spite of the development of the most PTT/PDT materials with good tumor-inhibitory effect, there are some disadvantages of photosensitizers and photothermal agents, such as low stability and low photonic efficiency, which greatly limit their further application. Therefore, in this study, a novel bismuth-based hetero-core-shell semiconductor nanomaterial BiNS-Fe@Fe with good photonic stability and synergistic theranostic functions was designed. On the one hand, BiNS-Fe@Fe with a high atomic number exhibits good X-ray absorption, enhanced magnetic resonance (MR) T₂-weighted imaging, and strong photoacoustic imaging (PAI) signals. In addition, the hetero-core-shell provides a strong barrier to decline the recombination of electron-hole pairs, inducing the generation of a large amount of reactive oxygen species (ROS) when irradiated with visible-NIR light. Meanwhile, a Fenton reaction can further increase ROS generation in the tumor microenvironment. Furthermore, an outstanding chemodynamic therapeutic potential was determined for this material. In particular, a high photothermal conversion efficiency (η = 37.9%) is of significance and could be achieved by manipulating surface decoration with Fe, which results in tumor ablation. In summary, BiNS-Fe@Fe could achieve remarkable utilization of ROS, high photothermal conversion law, and good chemodynamic activity, which highlight the multimodal theranostic potential strategies of tumors, providing a potential viewpoint for theranostic applications of tumors.

Nanoparticle contrast agents for X-ray imaging applications

X-ray imaging is the most widely used diagnostic imaging method in modern medicine and several advanced forms of this technology have recently emerged. Iodinated molecules and barium sulfate suspensions are clinically approved X-ray contrast agents and are widely used. However, these existing contrast agents provide limited information, are suboptimal for new X-ray imaging techniques and are developing safety concerns. Thus, over the past 15 years, there has been a rapid growth in the development of nanoparticles as X-ray contrast agents. Nanoparticles have several desirable features such as high contrast payloads, the potential for long circulation times, and tunable physicochemical properties. Nanoparticles have also been used in a range of biomedical applications such as disease treatment, targeted imaging, and cell tracking. In this review, we discuss the principles behind X-ray contrast generation and introduce new types of X-ray imaging modalities, as well as potential elements and chemical compositions that are suitable for novel contrast agent development. We focus on the progress in nanoparticle X-ray contrast agents developed to be renally clearable, long circulating, theranostic, targeted, or for cell tracking. We feature agents that are used in conjunction with the newly developed multi-energy computed tomography and mammographic imaging technologies. Finally, we offer perspectives on current limitations and emerging research topics as well as expectations for the future development of the field. This article is categorized under: Diagnostic Tools > in vivo Nanodiagnostics and Imaging Nanotechnology Approaches to Biology > Nanoscale Systems in Biology.

Renal-clearable hyaluronic acid functionalized NaGdF4 nanodots with enhanced tumor accumulation

Integration of high tumor-targeting capacity, controlling in vivo transport and low normal tissue retention into one engineered nanoparticle is a critical issue for future clinically translatable anti-cancer nanomedicines. Herein, hyaluronic acid functionalized 3.8 nm NaGdF4 nanodots (named NaGdF4 ND@HAs) have been prepared through conjugation of tryptone capped NaGdF4 nanodots (NaGdF4 ND@tryptone) with hyaluronic acid (HA, a naturally occurring glycosaminoglycan), which can recognize the overexpressed CD44 on cancer cell membranes. The as-prepared NaGdF4 ND@HAs have good paramagnetic properties (longitudinal relaxivity (r 1) = 7.57 × 10-3 M S-1) and low cytotoxicity. The in vivo experimental results demonstrate that the NaGdF4 ND@HAs can not only efficiently accumulate in mouse-bearing MDA-MB-231 tumors (ca. 5.3% injection dosage (ID) g-1 at 2 h post-injection), but also have an excellent renal clearance efficiency (ca. 75% injection dosage (ID) at 24 h post-injection). The as-prepared NaGdF4 ND@HAs have good paramagnetic properties with enhanced tumor-targeting capacity, which provides a useful strategy for the preparation of renal clearable magnetic resonance imaging (MRI) contrast agents for tumors.

Effective detection of bacteria using metal nanoclusters

Antibiotic-resistant bacterial infections cause more than 700 000 deaths each year worldwide. Detection of bacteria is critical in limiting infection-based damage. Nanomaterials provide promising sensing platforms owing to their ability to access new interaction modalities. Nanoclusters feature sizes smaller than traditional nanomaterials, providing great sensitive ability for detecting analytes. The distinct optical and catalytic properties of nanoclusters combined with their biocompatibility enables them as efficient biosensors. In this review, we summarize multiple strategies that utilize nanoclusters for detection of pathogenic bacteria.

Enhanced melanoma cell-killing by combined phototherapy/radiotherapy using a mesoporous platinum nanostructure

BACKGROUND

Metal nanomaterials have a significant potential as photosensitizer and radiosensitizer. The purpose of this study was to evaluate the cytotoxicity of a platinum mesoporous nanostructure (Pt MN) toward a melanoma cancer cell line upon combined laser radiation (808 nm, 1 and 1.5 W cm^-2) and X-ray irradiation (6 MV, 2, 4, and 6 Gy).

METHODS

Pt MN was synthesized by a simple procedure and characterized by field emission scanning and transmission electron microscopy. A mouse malignant melanoma cell line C540 (B16/F10) was treated with Pt MN, laser light and/or X-ray.

RESULTS

Pt MN had a mesoporous structure with a sponge-resemble shape comprised of ensembles of very small adhered particles of <11 nm and about 5-nm pores. While Pt MN represented a low toxicity toward and considerable uptake into the cell line in a concentration range of 10-100 μg mL^-1, laser light radiation alone was also not toxic, and X-ray irradiation alone induced a limited toxicity, Pt MN was toxic against the cells in a dose dependent manner upon laser light radiation, X-ray irradiation, or their combined exposure. The killing efficacy of Pt MN upon X-ray irradiation was more obvious at 72 h post-treatment. The combined exposure (laser radiation followed by X-ray irradiation) led to a deep cell killing and a very low melanoma cell viability (∼1%). Significant melanoma cancer cell killing of Pt MN was due to reactive oxygen species (ROS) production upon combined exposure of laser and X-ray, while cell killing upon laser light radiation was due to heat generation.

CONCLUSION

Pt MN was introduced as a supreme laser/X-ray sensitizer for treatment of cancer with a high ability to produce ROS and a potent impact on decreasing cell viability.

Multifunctional MoS2 nanosheets with Au NPs grown in situ for synergistic chemo-photothermal therapy

The treatment of cancer has always been a worldwide problem. The combination of chemotherapy and other therapies would be a promising therapy strategy. Photothermal therapy (PTT) does not cause serious side effects and has dual control of time and space, which was considered to be a good method for combination with chemotherapy. Here, we modified multifunctional nanosheets based on in-situ gold nanoparticles (Au NPs) grown molybdenum disulfide (MoS₂) to combine their excellent photothermal conversion and drug loading capabilities. More importantly, the target peptide cRGD modified nanosheets have good selectivity to tumor cells rich in integrin receptors, and drug loading and drug release tests showed that it could carry enough chemotherapeutic drugs and had excellent photo controlled release performance. In vitro cell experiments showed that the drug-loaded multifunctional nanosheets had good anti-tumor effect under 808 nm laser irradiation. Therefore, the multifunctional nanosheets designed in this paper have great potential in the study of targeted drug release and chemo-photothermal therapy combined therapy, and are of great significance for in vivo and clinical research.

Rhenium Sulfide Nanoparticles as a Biosafe Spectral CT Contrast Agent for Gastrointestinal Tract Imaging and Tumor Theranostics in Vivo

Spectral computed tomography (CT) imaging as a novel imaging technique shows promising prospects in the accurate diagnosis of various diseases. However, clinically iodinated contrast agents suffer from poor signal-to-noise ratio, and emerging heavy-metal-based CT contrast agents arouse great biosafety concern. Herein, we show the fabrication of rhenium sulfide (ReS₂) nanoparticles, a clinic radiotherapy sensitizer, as a biosafe spectral CT contrast agent for the gastrointestinal tract imaging and tumor theranostics in vivo by teaching old drugs new tricks. The ReS₂ nanoparticles were fabricated in a one-pot facile method at room temperature, and exhibited sub-10 nm size, favorable monodispersity, admirable aqueous solubility, and strong X-ray attenuation capability. More importantly, the proposed nanoparticles possess an outstanding spectral CT imaging ability and undoubted biosafety as a clinic therapeutic agent. Besides, the ReS₂ nanoparticles possess appealing photothermal performance due to their intense near-infrared absorption. The proposed nano-agent not only guarantees obvious contrast enhancement in gastrointestinal tract spectral CT imaging in vivo, but also allows effective CT imaging-guided tumor photothermal therapy. The proposed "teaching old drugs new tricks" strategy shortens the time and cuts the cost required for clinical application of nano-agents based on existing clinical toxicology testing and trial results, and lays down a low-cost, time-saving, and energy-saving method for the development of multifunctional nano-agents toward clinical applications.

Bi-DTPA as a high-performance CT contrast agent for in vivo imaging

Clinically used iodinated computer tomography (CT) contrast agents suffer from low sensitivity, and the emerging lanthanide-chelates and CT imaging nanoagents raise great safety concerns. The fusion of high sensitivity and good biocompatibility is highly desired for the development of CT contrast agents. Herein, we propose a facile and green one-pot synthesis strategy for the fabrication of a small molecular CT contrast agent, Bi-diethylene triamine pentaacetate acid (DTPA) complex, for high-performance CT and spectral CT imaging. The Bi-DTPA exhibits yield of near 100%, outstanding water solubility, favorable biocompatibility, large-scale production capability, and superior X-ray attenuation ability, and is successfully applied in high-quality in vivo kidney imaging and gastrointestinal tract CT imaging and appealing spectral CT imaging. The proposed contrast agent can be rapidly excreted from body, avoiding the potential side effects caused by the long-term retention in vivo. Furthermore, our design shows great potential in developing diverse multifunctional contrast agents via chemical modification. The proposed Bi-DTPA with unique superiorities shows a bright prospect in clinic CT imaging, especially spectral CT imaging, and lays down a new way for the design of high-performance CT contrast agents with great clinical transformation potential.

Facile Fabrication of Magnetic Microrobots Based on Spirulina Templates for Targeted Delivery and Synergistic Chemo-Photothermal Therapy

Magnetic microrobots can be actuated in fuel-free conditions and are envisioned for biomedical applications related to targeted delivery and therapy in a minimally invasive manner. However, mass fabrication of microrobots with precise propulsion performance and excellent therapeutic efficacy is still challenging, especially in a predictable and controllable manner. Herein, we propose a facile technique for mass production of magnetic microrobots with multiple functions using Spirulina ( Sp.) as biotemplate. Core-shell-structured Pd@Au nanoparticles (NPs) were synthesized in Sp. cells by electroless deposition, working as photothermal conversion agents. Subsequently, the Fe₃O₄ NPs were deposited onto the surface of the obtained (Pd@Au)@ Sp. particles via a sol-gel process, enabling them to be magnetically actuated. Moreover, the anticancer drug doxorubicin (DOX) was loaded on the (Pd@Au)/Fe₃O₄@ Sp. microrobots, which endows them with additional chemotherapeutic efficacy. The as-prepared biohybrid (Pd@Au)/Fe₃O₄@ Sp.-DOX microrobots not only possess efficient propulsion performance with the highest speed of 526.2 μm/s under a rotating magnetic field but also have enhanced synergistic chemo-photothermal therapeutic efficacy. Furthermore, they can be structurally disassembled into individual particles under near-infrared (NIR) laser irradiation and exhibit pH- and NIR-triggered drug release. These intriguing properties enable the microrobots to be a very promising and efficient platform for drug loading, targeted delivery, and chemo-photothermal therapy.

Fabrication of silver seeds and nanoparticle on core-shell Ag@SiO2 nanohybrids for combined photothermal therapy and bioimaging

In this study, two core-shell nanohybrids of different morphologies, namely SiO₂-coated silver (Ag) with surface-exposed silver seeds (Ag@SiO₂@Ag_seed) and SiO₂-coated Ag with surface-exposed Ag nanoparticles (Ag@SiO₂@Ag_NPs), were fabricated using the Stober method. Potential applications in bioimaging and photothermal therapy (PTT) of the two fabricated nanohybrids were also explored. Upon exposure to visible light (400 nm), Ag@SiO₂@Ag_seed with surface-exposed Ag seeds exhibited greater photothermal conversion efficiency than Ag@SiO₂@Ag_NPs. In vitro MTT assays in the dark and subsequent bioimaging using HeLa cells proved the potential biocompatibility of the fabricated core-shell nanohybrids. PTT applications of the two fabricated core-shell nanohybrids were studied by incubating HeLa cells with the nanohybrids, exposure to 400 nm laser, and subsequent staining with annexin V and propidium iodide (PI), and the two core-shell nanohybrids gave distinctively different PI staining results. Interestingly, Ag@SiO₂@Ag_seed caused higher cell death upon light exposure compared to Ag@SiO₂@Ag_NPs as the former generated more heat within the cells. These results demonstrated potential bioimaging and PPT applications of the fabricated core-shell nanohybrids and offer a novel candidate for phototherapy-based biomedical applications.

Photothermal effect of Ag nanoparticles deposited over poly(amidoamine) grafted carbon nanotubes

This paper illustrates the potential of Ag nanoparticles based nanocomposites to use as effective agents in photothermal therapy apart from their traditional employment as antimicrobial materials. Herein an Near- Infrared active photothermal agent was fabricated by deposition of Ag nanoparticles over aromatic poly(amidoamine) grafted carbon nanotubes. Thus prepared CNTs-PAMAM-Ag possessed strong photothermal effect under exposure to 980 nm laser system and prominent photothermal stability. The photothermal conversion efficiency of CNTs-PAMAM-Ag was found to be higher than readily used Au and CuS based photothermal agents. The photothermal effect of CNTs-PAMAM-Ag was substantial in presence of 980 nm laser compared to 808 nm laser and a linear dependence of photothermal effect on its concentration was identified. The maximum temperature attained by CNTs-PAMAM-Ag during assessment of its photothermal effect was about 66.0 °C, which is significantly higher than the survival temperature level of cancer cells. So CNTs-PAMAM-Ag could be a promising photothermal agent to apply in future photothermal hyperthermia therapy to treat cancer. Moreover CNTs-PAMAM-Ag can synchronous trigger by a single wavelength (980 nm) laser system, so it could simplify the future therapeutic process.

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.

2D transition metal dichalcogenide nanosheets for photo/thermo-based tumor imaging and therapy

Two-dimensional (2D) graphene-like nanomaterials show wide applications in the fields of nanodevices, sensors, energy materials, catalysis, drug delivery, bioimaging, and tissue engineering. Recently, many studies have been focused on the synthesis and application of 2D transition metal dichalcogenide (TMD) nanosheets for various biomedical applications. In particular, 2D TMD nanosheets exhibit great advantages for tumor imaging and therapy compared to some traditional nanomaterials due to their high specific surface area, good biocompatibility, easy modification, and ultrahigh light and heat conversion efficiency. In this review, we summarize the recent advances in the synthesis, modification, and photo/thermo-based tumor imaging and therapy of 2D TMD nanosheets. The important studies on tumor bioimaging with TMD nanosheets, such as X-ray computed tomography, magnetic resonance imaging, and photoacoustic imaging, are demonstrated and discussed. In another section, the physical photothermal and photodynamic therapies as well as the pharmacological therapy of tumors with TMD nanosheet-based nanohybrids are introduced. It is expected that this work will be valuable for readers to understand the synthesis and modification of TMD nanosheets to design novel 2D functional nanomaterials for photo/thermo-based tumor imaging and therapy in one aspect, and in another aspect will extend the applications of TMD-based nanomaterials in materials science, analytical science, electrocatalysis, tissue engineering, and others.

Multifunctional Bi@PPy-PEG Core-Shell Nanohybrids for Dual-Modal Imaging and Photothermal Therapy

High-performance theranostic nanoagents, which integrate multimodal imaging and photothermal therapy for clinical anticancer treatment, are highly desired. Herein, we report the synthesis and bioapplication of a multifunctional theranostic nanoagent based on polyethylene glycol (PEG)-modified polypyrrole (PPy)-coated bismuth (Bi) nanohybrids (referred to as Bi@PPy-PEG NHs) for X-ray computed tomography/photoacoustic (CT/PA) dual-modal imaging and photothermal therapy (PTT). The obtained Bi@PPy-PEG NHs have a distinct core-shell structure with the metallic Bi nanoparticle as the inner core and the PPy-PEG layer as the shell. The Bi@PPy-PEG NHs show excellent physiological stability and compatibility, without noticeable cytotoxicity. Importantly, the NHs exhibit strong NIR absorbance and remarkable photothermal conversion capability and conversion stability, with the photothermal conversion efficiency as high as ∼46.3%. Thanks to the strong PTT effect, highly effective photothermal ablation on cancer cells has been achieved both in vitro and in vivo. Furthermore, a high-contrast in vitro and in vivo CT/PA dual-modal imaging has been realized, showing great potential to provide comprehensive diagnosis information for antitumor treatment. In particular, the CT enhancement efficiency of the NHs is of ∼14.4 HU mM^-1, which is ∼3.7-fold that of clinically used iohexol. Therefore, our work highlights the potential of using such core-shell Bi@PPy-PEG NHs as a versatile theranostic nanoplatform for cancer imaging and therapy.

Ultrasmall Superparamagnetic Iron Oxide Nanoparticle for T2-Weighted Magnetic Resonance Imaging

A facile method to synthesize ultrasmall-sized supermagnetic iron oxide nanoparticles with good monodispersity and high relaxivity is desired for magnetic resonance imaging (MRI) technology. Herein, we have developed a one-step method to direct the formation of superparamagnetic iron oxide nanoparticle (uBSPIO) using albumin under mild conditions. The resulting uBSPIO possess ultrasmall size (4.78 ± 0.55 nm) and super high MR relaxivity (444.56 ± 8.82 mM^-1 s^-1). After grafted by the luteinizing hormone release hormone peptide (LHRH), the uBSPIO could targeted and accumulated in the tumor site. Finally, the uBSPIOs had good stability and did not induce cytotoxicity in vitro or major organ toxicity in vivo. The uBSPIOs are promising contrast agents for MRI.

Biocompatible Iron Phthalocyanine-Albumin Assemblies as Photoacoustic and Thermal Theranostics in Living Mice

Exploring novel and versatile nanomaterials for the construction of personalized multifunctional phototheranostics with significant potentials in bioimaging-guided tumor phototherapies has attracted considerable attention. Herein, the phototheranostic agent human serum albumin-iron (II) phthalocyanine FePc nanoparticles (HSA-FePc NPs) were fabricated for photoacoustic (PA) imaging-guided photothermal therapy (PTT) of cancer in vivo. The prepared HSA-FePc NPs exhibited high stability, efficient NIR absorption, good capability and stability of photothermal behavior with a high photothermal conversion efficiency of ∼44.4%, high contrast and spatial resolution of PA imaging, efficient cancer therapy, and low long-term toxicity. This potent multifunctional phototheranostic is, therefore, very promising and favorable for effective, precise, and safe antitumor treatment in clinical application.

Fluorescent metal quantum clusters: an updated overview of the synthesis, properties, and biological applications

A brief history of metal quantum clusters, their synthesis methods, physical properties, and an updated overview of their applications is provided.