Novel Bismuth-Based Nanomaterials Used for Cancer Diagnosis and Therapy

Synthesis of folate targeted theranostic cubosomal platform for co-delivery of bismuth oxide and doxorubicin to melanoma in vitro and in vivo

Liquid crystalline nanoparticles (LCNPs) have gained much attention in cancer nanomedicines due to their unique features such as high surface area, storage stability, and sustained-release profile. In the current study, a novel LCNP for co-encapsulation of Bi2O3 and hydrophilic doxorubicin (DOX) was fabricated and functionalized with folic acid (FA) to achieve efficient tumor targeting toward CT-scan imaging and chemotherapy of melanoma in vitro and in vivo. LCNPs Bi2O3 NPs were prepared using glycerol monooleate-pluronic F-127 (GMO/PF127/water). Firstly, GMO/water were homogenized to prepare LC gel. Then, the stabilizer aqueous solution (PF127/Bi2O3/DOX) was added to the prepared LC gel and homogenized using homogenization and ultrasonication. The formulated NPs exhibited superior stability with encapsulation efficiency. High cytotoxicity and cellular internalization of the FA-Bi2O3-DOX-NPs were observed in comparison with Bi2O3-DOX-NPs and the free DOX in folate-receptor (FR) overexpressing cells (B16F10) in vitro. Moreover, ideal tumor suppression with increased survival rate were observed in tumorized mice treated with FA-Bi2O3-DOX-NPs compared to those treated with non-targeted one. On the other hand, the CT-imaging ability of the Bi2O3-DOX-NPs was tested inB16F10 tumor-bearing mice. The obtained data indicated a high potential of the developed targeted theranostic FA-Bi2O3-DOX-NPs for diagnostics and treatment of melanoma.

Chiral Carbon Dots and Chiral Carbon Dots with Circularly Polarized Luminescence: Synthesis, Mechanistic Investigation and Applications

Chiral carbon dots (CCDs) can be widely used in various fields such as chiral recognition, chiral catalysis and biomedicine because of their unique optical properties, low toxicity and good biocompatibility. In addition, CCDs with circularly polarized luminescence (CPL) can be synthesized, thus broadening the prospects of CCDs applications. Since the research on CCDs is still in its infancy, this paper reviews the chiral origin, formation mechanism, chiral evolution, synthesis and emerging applications of CCDs, with a special focus on CCDs with CPL activity. It is hoped that it will provide some reference to solve the current problems faced by CCDs. Finally, the opportunities and challenges of the current research on CCDs are described, and their future development trends have also been prospected.

Copper indium selenium nanomaterials for photo-amplified immunotherapy through simultaneously enhancing cytotoxic T lymphocyte recruitment and M1 polarization of macrophages

Photoactivated immunotherapy has promising therapeutic efficacy for treating malignancies, especially metastatic tumors. In this study, an erythrocyte membrane-encapsulated copper indium selenium (RCIS) semiconductor nanomaterial was developed to eliminate primary and metastatic tumors, in which copper ions can induce chemodynamic performance, and the narrow band gap endows RCIS with the properties of near-infrared (NIR) light-activated photothermal and photodynamic amplified immunotherapy. Furthermore, RCIS can be used as a nanocarrier to form RNCIS nanoparticles (NPs) by loading NLG919, which blocks the indoleamine 2,3-dioxygenase-1. Under NIR light irradiation, RNCIS NPs release NLG919 at tumor sites via photothermal properties, thereby promoting the recruitment of cytotoxic T lymphocytes and M1 polarization of macrophages, targeting the activation and amplification of immune responses. Herein, in vitro and in vivo studies showed that RNCIS NPs effectively kill cancer cells and eliminate primary and metastatic tumors. Therefore, this study suggests that semiconductor nanomaterials with narrow bandgaps have great potential as photoimmunotherapy agents and NIR light-responsive nanocarriers for controlled release, providing a great paradigm for synergetic tumor photoimmunotherapy. STATEMENT OF SIGNIFICANCE: The Erythrocyte membrane-coated, NLG919-loaded copper indium selenium (RNCIS) semiconductor was designed for eliminating primary and metastatic tumors. RNCIS exhibits chemodynamic, photodynamic, and photothermal activated immunotherapy by inhibiting indoleamine 2,3-dioxygenase-1. This can enhance the recruitment of cytotoxic T lymphocyte and M1 polarization of macrophage, leading to higher synergetic photo-immune therapeutic efficacy.

Tween-20-Modified BiVO4 Nanorods for CT Imaging-Guided Radiotherapy of Tumor

Oral cancer is the most common malignant tumor in the oral and maxillofacial region, which seriously threatens the health of patients. At present, radiotherapy is one of the commonly used methods for oral cancer treatment. However, the resistance of cancerous tissues to ionizing radiation, as well as the side effects of X-rays on healthy tissues, still limit the application of radiotherapy. Therefore, how to effectively solve the above problems is still a challenge at present. Generally speaking, elements with high atomic numbers, such as bismuth, tungsten, and iodine, have a high X-ray attenuation capacity. Using nanomaterials containing these elements as radiosensitizers can greatly improve the radiotherapy effect. At the same time, the modification of nanomaterials based on the above elements with the biocompatible polymer can effectively reduce the side effects of radiosensitizers, providing a new method for the realization of efficient and safe radiotherapy for oral cancer. In this work, we prepared Tween-20-modified BiVO₄ nanorods (Tw20-BiVO₄ NRs) and further used them in the radiotherapy of human tongue squamous cell carcinoma. Tw20-BiVO₄ NRs are promising radiosensitizers, which can generate a large number of free radicals under X-rays, leading to the damage of cancer cells and thus playing a role in tumor therapy. In cell experiments, radiotherapy sensitization of Tw20-BiVO₄ NRs significantly enhanced the production of free radicals in oral cancer cells, aggravated the destruction of chromosomes, and improved the therapeutic effect of radiotherapy. In animal experiments, the strong X-ray absorption ability of Tw20-BiVO₄ NRs makes them effective contrast agents in computed tomography (CT) imaging. After the tumors are located by CT imaging, it helps to apply precise radiotherapy; the growth of subcutaneous tumors in nude mice was significantly inhibited, confirming the remarkable effect of CT imaging-guided radiotherapy.

Low-dimensional nanomaterials as an emerging platform for cancer diagnosis and therapy

The burden of cancer is increasing, being widely recognized as one of the main reasons for deaths among humans. Despite the tremendous efforts that have been made worldwide to stem the progression and metastasis of cancer, morbidity and mortality in malignant tumors have been clearly rising and threatening human health. In recent years, nanomedicine has come to occupy an increasingly important position in precision oncotherapy, which improves the diagnosis, treatment, and long-term prognosis of cancer. In particular, LDNs with distinctive physicochemical capabilities have provided great potential for advanced biomedical applications, attributed to their large surface area, abundant surface binding sites, and good cellular permeation properties. In addition, LDNs can integrate CT/MR/US/PAI and PTT/PDT/CDT/NDDS into a multimodal theranostic nanoplatform, enabling targeted therapy and efficacy assessments for cancer. This review attempts to concisely summarize the classification and major properties of LDNs. Simultaneously, we particularly emphasize their applications in the imaging, diagnosis, and treatment of cancerous diseases.

Bismuth-coated 80S15C bioactive glass scaffolds for photothermal antitumor therapy and bone regeneration

Background: Malignant bone tumors usually occur in young people and have a high mortality and disability rate. Surgical excision commonly results in residual bone tumor cells and large bone defects, and conventional radiotherapy and chemotherapy may cause significant side effects. In this study, a bifunctional Bi-BG scaffold for near-infrared (NIR)-activated photothermal ablation of bone tumors and enhanced bone defect regeneration is fabricated. Methods: In this study, we prepared the Bi-BG scaffold by in-situ generation of NIR-absorbing Bi coating on the surface of a 3D-printing bioactive glass (BG) scaffold. SEM was used to analyze the morphological changes of the scaffolds. In addition, the temperature variation was imaged and recorded under 808 nm NIR laser irradiation in real time by an infrared thermal imaging system. Then, the proliferation of rat bone mesenchymal stem cells (rBMSCs) and Saos-2 on the scaffolds was examined by CCK-8 assay. ALP activity assay and RT-PCR were performed to test the osteogenic capacity. For in vivo experiments, the nude rat tumor-forming and rat calvarial defect models were established. At 8 weeks after surgery, micro-CT, and histological staining were performed on harvested calvarial samples. Results: The Bi-BG scaffolds have outstanding photothermal performance under the irradiation of 808 nm NIR at different power densities, while no photothermal effects are observed for pure BG scaffolds. The photothermal temperature of the Bi-BG scaffold can be effectively regulated in the range 26-100°C by controlling the NIR power density and irradiation duration. Bi-BG scaffolds not only significantly induces more than 95% of osteosarcoma cell death (Saos-2) in vitro, but also effectively inhibit the growth of bone tumors in vivo. Furthermore, they exhibit excellent capability in promoting osteogenic differentiation of rBMSCs and finally enhance new bone formation in the calvarial defects of rats. Conclusion: The Bi-BG scaffolds have bifunctional properties of photothermal antitumor therapy and bone regeneration, which offers an effective method to ablate malignant bone tumors based on photothermal effect.

A review on bismuth-based materials for the removal of organic and inorganic pollutants

Modernized lifestyle and increased industrialization threaten living organisms because of the pollutants released from industries and household wastes. The presence of even small amounts of pollutants (organic pollutants (OPs) and inorganic pollutants-heavy metals (HMs)) shows significant effects. Thus wastewater treatment is urgently needed before being subjected to use. Many methods and materials have been developed and reported for the removal of pollutants from wastewater. This review focused on the removal of both OPs and HMs using bismuth-based (Bi-based) materials because of their low toxicity and excellent properties compared to other metals. Bi-based materials as a photocatalyst for photodegradation of OPs are discussed in detail with synthesis methods. Further, since few reviews are available on the Bi-based material for the removal and sensing of HMs, this topic was intentionally summarized. About 200 published articles and reviews have been reviewed here. Additionally, the key point that needs to be focused on the development of Bi-based photocatalysts for the removal of OPs and for upgrading the Bi-based materials as adsorbents for HMs are conferred in the outlook. This will help many researchers in their upcoming work.

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.

A Review on the Recent Advancements on Therapeutic Effects of Ions in the Physiological Environments

This review focuses on the therapeutic effects of ions when released in physiological environments. Recent studies have shown that metallic ions like Ag+, Sr2+, Mg2+, Mn2+, Cu2+, Ca2+, P+5, etc., have shown promising results in drug delivery systems and regenerative medicine. These metallic ions can be loaded in nanoparticles, mesoporous bioactive glass nanoparticles (MBGNs), hydroxyapatite (HA), calcium phosphates, polymeric coatings, and salt solutions. The metallic ions can exhibit different functions in the physiological environment such as antibacterial, antiviral, anticancer, bioactive, biocompatible, and angiogenic effects. Furthermore, the metals/metalloid ions can be loaded into scaffolds to improve osteoblast proliferation, differentiation, bone development, fibroblast growth, and improved wound healing efficacy. Moreover, different ions possess different therapeutic limits. Therefore, further mechanisms need to be developed for the highly controlled and sustained release of these ions. This review paper summarizes the recent progress in the use of metallic/metalloid ions in regenerative medicine and encourages further study of ions as a solution to cure diseases.

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.

Controllable synthesis of layered black bismuth oxidechloride nanosheets and their applications in internal tumor ablation

The recently emerging bismuth oxyhalide (BiOX) nanomaterials are promising indirect band gap photosensitizer for ultraviolet (UV) light triggered phototherapy due to their unique layered nanosheet structure. However, the low absorption and poor photothermal conversion efficiency have always impeded their further applications in cancer clinical therapy. Herein, BiOCl rich in oxygen vacancies has been reported to have full spectrum absorption properties, making it possible to achieve photothermal property under near-infrared (NIR) laser. Under 808 nm irradiation, the photothermal conversion efficiency of black BiOCl nanosheets (BBNs) is up to 40%. BBNs@PEG can effectively clear primary subcutaneous tumors and prevent recurrence, achieving good synergistic treatment effect. These results not only broke the limitation of ultraviolet on the BiOCl material and provided a good template for other semiconductor materials, also represent a promising approach to fabricate BBN@PEG a novel, potent and multi-functional theranostic platform for precise PTT and prognostic evaluation.

Fabrication of gelatin Bi2S3 capsules as a highly sensitive X-ray contrast agent for gastrointestinal motility assessment in vivo

Tiny BaSO₄ rod-based X-ray imaging is the most frequently-used method for clinical diagnosis of gastrointestinal motility disorders. The BaSO₄ rods usually have a small size to pass through the gastrointestinal tract smoothly, but suffer from unavoidably low sensitivity. Herein, we developed Bi₂S₃ capsules as a high-performance X-ray contrast agent for gastrointestinal motility assessment for the first time. The Bi₂S₃ capsules were synthesized by the encapsulation of commercial Bi₂S₃ powder into commercial gelatin capsules and subsequent coating of ultraviolet-curable resin. The prepared Bi₂S₃ capsules showed excellent biocompatibility in vitro and in vivo and superior X-ray attenuation ability due to the large atomic number and high K-edge value of Bi. The developed Bi₂S₃ capsules can serve as a small but highly sensitive X-ray contrast agent to quantitatively assess gastrointestinal motility in a vincristine-induced gastrointestinal motility disorder model in vivo by X-ray, CT and spectral CT imaging successfully, solving the intrinsic drawbacks of clinically used BaSO₄.

Bismuth Oxychloride Nanomaterials Fighting for Human Health: From Photodegradation to Biomedical Applications

Environmental pollution and various diseases seriously affect the health of human beings. Photocatalytic nanomaterials (NMs) have been used for degrading pollution for a long time. However, the biomedical applications of photocatalytic NMs have only recently been investigated. As a typical photocatalytic NM, bismuth oxychloride (BiOCl) exhibits excellent photocatalytic performance due to its unique layered structure, electronic properties, optical properties, good photocatalytic activity, and stability. Some environmental pollutants, such as volatile organic compounds, antibiotics and their derivatives, heavy metal ions, pesticides, and microorganisms, could not only be detected but also be degraded by BiOCl-based NMs due to their excellent photocatalytic and photoelectrochemical properties. In particular, BiOCl-based NMs have been used as theranostic platforms because of their CT and photoacoustic imaging abilities, as well as photodynamic and photothermal performances. However, some reviews have only profiled the applications of dye degradation, hydrogen or oxygen production, carbon dioxide reduction, or nitrogen fixation of BiOCl NMs. There is a notable knowledge gap regarding the systematic study of the relationship between BiOCl NMs and human health, especially the biomedical applications of BiOCl-based NMs. As a result, in this review, the recent progress of BiOCl-based photocatalytic degradation and biomedical applications are summarized, and the improvement of BiOCl-based NMs in environmental and healthcare fields are also discussed. Finally, a few insights into the current status and future perspectives of BiOCl-based NMs are given.

Controlled supramolecular interaction to enhance the bioavailability of hesperetin to targeted cancer cells through graphyne: a comprehensive in silico study

In the current study, the drug carrier efficiency of graphyne (GRP) for the transfer of the hesperetin (HPT) drug is evaluated for the first time. The GRP efficacy as a carrier is investigated using the density functional theory (DFT) technique to calculate various physiochemical characteristics such as dipole moment, bandgap, and chemical reactivity-descriptors for HPT, GRP and HPT@GRP complex. The non-covalent-interaction (NCI) plot indicated that GRP and HPT have weak interaction force, which is fundamental for the drug's noticeable offloading from the GRP carrier at its target location. According to frontier molecular orbital analysis, the highest occupied molecular orbital (HOMO) of HPT distributes the charge to the GRP, the lowest unoccupied molecular orbital (LUMO) during excitation. Charge transfer is further supported by charge-decomposition-analysis, which interprets the extensive overlap between HPT and GRP orbitals. In the case of the gas phase, the λ_max of the HPT@GRP-complex is redshifted by 9 nm from GRP. In the solvent phase, the λ_max value is also redshifted. These theoretically calculated spectra also match experimentally observed spectra rather well. The PET (photoinduced electron-transfer) method and electron–hole theory were used for the graphical explication of distinct excited states. The photoinduced electron transfer (PET) mechanism interprets fluorescence dimming because of interaction. Furthermore, GRP with cationic (+1) and anionic (−1) charge states (GRP^+1/−1) showed minor structural disfigurement and formed stable HPT complexes. In the current study, HRP is loading and unloading on GRP very effectively, that can potentially be used in the oncology field. Due to this theoretical study, researchers will be interested in looking at other 2D nanomaterials for drug delivery applications.

In the current study, the drug carrier efficiency of graphyne (GRP) for the transfer of the hesperetin (HPT) drug is evaluated for the first time.

One-pot synthesis of flower-like Bi2S3 nanoparticles for spectral CT imaging and photothermal therapy in vivo

A facile and green strategy was developed for fabricating Bi2S3 nanoparticles for spectral CT imaging and photothermal therapy in vivo.

Harnessing X-Ray Energy-Dependent Attenuation of Bismuth-Based Nanoprobes for Accurate Diagnosis of Liver Fibrosis

Timely detection of liver fibrosis by X-ray computed tomography (CT) can prevent its progression to fatal liver diseases. However, it remains quite challenging because conventional CT can only identify the difference in density instead of X-ray attenuation characteristics. Spectral CT can generate monochromatic imaging to specify X-ray attenuation characteristics of the scanned matter. Herein, an X-ray energy-dependent attenuation strategy originated from bismuth (Bi)-based nanoprobes (BiF3 @PDA@HA) is proposed for the accurate diagnosis of liver fibrosis. Bi element in BiF3 @PDA@HA can exhibit characteristic attenuation depending on different levels of X-ray energy via spectral CT, and that is challenging for conventional CT. In this study, selectively accumulating BiF3 @PDA@HA nanoprobes in the hepatic fibrosis areas can significantly elevate CT value for 40 Hounsfield units on 70 keV monochromatic images, successfully differentiating from healthy livers and achieving the diagnosis of liver fibrosis. Furthermore, the enhancement produced by the BiF3 @PDA@HA nanoprobes in vivo increases as the monochromatic energy decreases from 70 to 40 keV, optimizing the conspicuity of the diseased areas. As a proof of concept, the strategically designed nanoprobes with energy-dependent attenuation characteristics not only expand the scope of CT application, but also hold excellent potential for precise imaging-based disease diagnosis.

Structurally restricted Bi(III) metallation of apo-βMT1a: metal-induced tangling

Non-toxic bismuth salts are used in anti-ulcer medications and to protect against nephrotoxicity from anticancer drugs. Bismuth salts also induce metallothionein (MT), a metal-binding protein that lacks a formal secondary structure. We report the impact on the metallation properties of Bi(III) to the 9-cysteine β fragment of MT as a function of cysteine accessibility using electrospray ionization mass spectrometry. At pH 7.4, Bi2βMT formed cooperatively. Cysteine modification shows that each Bi(III) was terminally bound to three cysteinyl thiolates. Non-cooperative Bi(III) binding was observed at pH 2.3, where cysteine accessibility is increased. However, competition from H4EDTA inhibited Bi(III) binding. When GdmCl, a well-known denaturing agent, was used to increase cysteine accessibility of the apoβMT at pH 7.4, a greater fraction of Bi3βMT formed using all nine cysteines. The change in binding profile and equilibrium of Bi2βMT was determined as a function of acidification, which changed as a result of competition with H4EDTA. There was no Bi(III) transfer between Bi2βMT, Cd3βMT, and Zn3βMT. This lack of metal exchange and the resistance towards binding the third Bi(III) suggest a rigidity in the Bi2βMT binding sites that inhibits Bi(III) mobility. These experiments emphasize the conformational control of metallation that results in substantially different metallated products: at pH 7.4 (many cysteines buried) Bi2βMT, whereas at pH 7.4 (all cysteines accessible) enhanced formation of Bi3βMT. These data suggest that the addition of the first two Bi(III) crosslinks the protein, blocking access to the remaining three cysteines for the third Bi(III), as a result of tangle formation.

Pnictogen Semimetal (Sb, Bi)-Based Nanomaterials for Cancer Imaging and Therapy: A Materials Perspective

Innovative multifunctional nanomaterials have attracted tremendous interest in current research by facilitating simultaneous cancer imaging and therapy. Among them, antimony (Sb)- and bismuth (Bi)-based nanoparticles are important species with multifunction to boost cancer theranostic efficacy. Despite the rapid development, the extensive previous work treated Sb- and Bi-based nanoparticles as mutually independent species, and therefore a thorough understanding of their relationship in cancer theranostics was lacking. We propose here that the identical chemical nature of Sb and Bi, being semimetals, provides their derived nanoparticles with inherent multifunction for near-infrared laser-driven and/or X-ray-based cancer imaging and therapy as well as some other imparted functions. An overview of recent progress on Sb- and Bi-based nanoparticles for cancer theranostics is provided to highlight the relationship between chemical nature and multifunction. The understanding of Sb- and Bi-based nanoparticles in this way might shed light on the further design of smart multifunctional nanoparticles for cancer theranostics.

Recent Advances and Implication of Bioengineered Nanomaterials in Cancer Theranostics

Cancer is one of the most common causes of death and affects millions of lives every year. In addition to non-infectious carcinogens, infectious agents contribute significantly to increased incidence of several cancers. Several therapeutic techniques have been used for the treatment of such cancers. Recently, nanotechnology has emerged to advance the diagnosis, imaging, and therapeutics of various cancer types. Nanomaterials have multiple advantages over other materials due to their small size and high surface area, which allow retention and controlled drug release to improve the anti-cancer property. Most cancer therapies have been known to damage healthy cells due to poor specificity, which can be avoided by using nanosized particles. Nanomaterials can be combined with various types of biomaterials to make it less toxic and improve its biocompatibility. Based on these properties, several nanomaterials have been developed which possess excellent anti-cancer efficacy potential and improved diagnosis. This review presents the latest update on novel nanomaterials used to improve the diagnostic and therapeutic of pathogen-associated and non-pathogenic cancers. We further highlighted mechanistic insights into their mode of action, improved features, and limitations.

Nanozyme-Incorporated Biodegradable Bismuth Mesoporous Radiosensitizer for Tumor Microenvironment-Modulated Hypoxic Tumor Thermoradiotherapy

Solid tumors inevitably develop radioresistance due to low oxygen partial pressure in the tumor microenvironment. Despite numerous attempts, there are still few effective ways to avoid the hypoxia-induced poor radiotherapeutic effect. To overcome this problem, platinum (Pt) nanodots were fabricated into a mesoporous bismuth (Bi)-based nanomaterial to construct a biodegradable nanocomposite BiPt-folic acid-modified amphiphilic polyethylene glycol (PFA). BiPt-PFA could act as a radiosensitizer to enhance the absorption of X-rays at the tumor site and simultaneously trigger response behaviors related to the tumor microenvironment due to the enrichment of materials in the tumor area. During this process, the Bi-based component consumed glutathione via coordination, thus altering the oxidative stress balance, while Pt nanoparticles catalyzed the decomposition of hydrogen peroxide to generate oxygen, thereby relieving tumor hypoxia. Both Pt and Bi thus co-modulated the tumor microenvironment to improve the radiotherapeutic effect. In addition, Pt dots in BiPt-PFA had strong near-infrared absorption ability and created an intensive photothermal therapeutic effect. Modulation of the tumor microenvironment could thus improve the therapeutic effect in hypoxic tumors by a combination of photothermal therapy and enhanced radiotherapy. BiPt-PFA, as a biodegradable nanocomposite, may thus modulate the tumor microenvironment to enhance the hypoxic tumor therapeutic effect by thermoradiotherapy.

Few-Layer Bismuthene for Checkpoint Knockdown Enhanced Cancer Immunotherapy with Rapid Clearance and Sequentially Triggered One-for-All Strategy

As a conceptually attractive strategy, the use of immune checkpoint blockade antibodies to treat cancer is limited due to the restrained tumor-infiltrating lymphocytes (TILs), poor accumulation and penetration of antibodies, and deficient checkpoint blockade in malignancies. In this study, we describe a pH and mild photothermal sequentially triggered PD-L1 siRNA release nanosystem, based on monoelemental bismuthene, as a one-for-all strategy to realize enhanced tumor mild photothermal immunotherapy. Under manually controlled NIR irradiation, the bismuthene-based nanosystem simultaneously induces a tumor-enhanced pathological permeability and retention (EPPR) effect, increases TIL recruitment, and triggers programmed siRNA release, thereby amplifying anti-PD-L1 immunotherapy. In addition, the nanosystem's rapid removal through intestinal and renal clearance mitigates toxicity risk associated with long-term retention. In vivo antitumor experiments demonstrate that this bismuthene-based nanosystem is a promising and effective approach for "cold" tumor management.

Suppressing the Radiation-Induced Corrosion of Bismuth Nanoparticles for Enhanced Synergistic Cancer Radiophototherapy

The level of tumor killing by bismuth nanoparticles (BiNPs) as radiosensitizers depends strongly on the powerful particle-matter interaction. However, this same radiation leads to the structural damage in BiNPs, consequently weakening their specific physicochemical properties for radiosensitization. Herein, we studied the radiation-induced corrosion behavior of BiNPs and demonstrated that these damages were manifested by the change in their morphology and crystal structure as well as self-oxidation at their surface. Furthermore, artificial heterostructures were created with graphene nanosheets to greatly suppress the radiation-induced corrosion in BiNPs and enhance their radiocatalytic activity for radiotherapy enhancement. Such a nanocomposite allows the accumulation of overexpressed glutathione, a natural hole scavenger, at the reaction interfaces. This enables the rapid removal of radiogenerated holes from the surface of BiNPs and minimizes the self-radiooxidation, therefore resulting in an efficient suppression of radiation corrosion and a decrease of the depletion of reactive oxygen species (ROS). Meanwhile, the radioexcited conduction band electrons react with the high-level H₂O₂ within cancer cells to yield more ROS, and the secondary electrons are trapped by H₂O molecules to produce hydrated electrons capable of reducing a highly oxidized species such as cytochrome c. These radiochemical reactions together with hyperthermia can regulate the tumor microenvironment and accelerate the onset of cellular redox disequilibrium, mitochondrial dysfunction, and DNA damage, finally triggering tumor apoptosis and death. The current work will shed light on radiosensitizers with an enhanced corrosion resistance for controllable and synergistic radio-phototherapeutics.

Improving the photothermal therapy efficacy and preventing the surface oxidation of bismuth nanoparticles through the formation of a bismuth@bismuth selenide heterostructure

Bismuth (Bi) nanoparticles (NPs) are emerging as promising photothermal agents for computed tomography imaging-guided photothermal therapy. However, it is challenging to improve their photothermal conversion efficacy and prevent their oxidation. Herein, Bi@bismuth selenide (Bi2Se3) core@shell NPs were designed and fabricated for improving the photothermal performance due to the staggered energy levels between Bi and Bi2Se3. With near-infrared light irradiation, both the materials could be excited to generate hot carriers due to their extremely narrow bandgaps. The hot electrons would transfer to the conduction band of Bi2Se3 and the hot holes to the valence band of Bi, leading to the effective separation of hot carriers. Then, these hot electrons and holes would recombine nonradiatively at the interface of Bi and Bi2Se3 and produce more phonons, resulting in an enhanced photothermal conversion efficacy. Moreover, the presence of Bi2Se3 on the surface of Bi NPs could prevent Bi from surface oxidation due to the higher stability of Bi2Se3. In fact, Bi@Bi2Se3 NPs showed excellent biocompatibility and photothermal therapeutic efficacy against cancer cells.

GO/Bi2S3 Doped PVDF/TPU Nanofiber Membrane with Enhanced Photothermal Performance

Photothermal conversion materials have attracted wide attention due to their efficient utilization of light energy. In this study, a (GO)/Bi2S3-PVDF/TPU composite nanofiber membrane was systematically developed, comprising GO/Bi2S3 nanoparticles (NPs) as a photothermal conversion component and PVDF/TPU composite nanofibers as the substrate. The GO/Bi2S3 NPs were synthesized in a one-step way and the PVDF/TPU nanofibers were obtained from a uniformly mixed co-solution by electrospinning. GO nanoparticles with excellent solar harvesting endow the GO/Bi2S3-PVDF/TPU membrane with favorable photothermal conversion. In addition, the introduction of Bi2S3 NPs further enhances the broadband absorption and photothermal conversion properties of the GO/Bi2S3-PVDF/TPU composite membrane due to its perfect broadband absorption performance and coordination with GO. Finally, the results show that the GO/Bi2S3-PVDF/TPU composite membrane has the highest light absorption rate (about 95%) in the wavelength range of 400-2500 nm. In the 300 s irradiation process, the temperature changes in the GO/Bi2S3-PVDF/TPU composite membrane were the most significant and rapid, and the equilibrium temperature of the same irradiation time was 81 °C. Due to the presence of TPU, the mechanical strength of the composite film was enhanced, which is beneficial for its operational performance. Besides this, the morphology, composition, and thermal property of the membranes were evaluated by corresponding test methods.

A review of bismuth-based sorptive materials for the removal of major contaminants from drinking water

In recent years, bismuth has gained attention of many researchers because of its sorptive properties. Sorptive properties of bismuth compounds are used for removal of ionic contaminants from aqueous solution. In this paper, an attempt is made to review the recent developments in the area of contaminant removal from aqueous solutions using bismuth-based media. List of various bismuth-based adsorbents are collected from published literature and their adsorption capacities are also compared. The methods of characterization of some of the synthesized bismuth-based materials have also been discussed. Hydrous bismuth oxides (HBOs) have sorptive potential for nitrate and fluoride removal from aqueous solution with maximum capacity of 0.508-0.512 mg/g and 0.60-1.93 mg/g respectively. Thus, it can be beneficially used for treatment of drinking water treatment, particularly in small scale household applications.

Bismuth-Based Nanomaterials: Recent Advances in Tumor Targeting and Synergistic Cancer Therapy Techniques

Despite all of the efforts in the field of cancer therapy, the heterogeneous properties of tumor cells induce an insufficient therapeutic outcome when treated with conventional monotherapies, necessitating a shift in cancer treatment from monotherapy to combination therapy for complete cancer treatment. Multifunctional bismuth (Bi)-based nanomaterials (NMs) with therapeutic functions hold great promise for the fields of cancer diagnosis and therapy based on their low toxicity, X-ray sensitive capabilities, high atomic number, near-infrared driven semiconductor properties, and low cost. Herein, a comprehensive review of recent advances in various medicinal aspects of Bi-based NMs is presented including: evaluation of in-tumor site accumulation, tumor targeting, and therapeutic performance, as well as the characteristics, benefits, and shortcomings of Bi-based NM-mediated major monotherapies. In addition, the cooperative enhancement mechanisms between two or more of these monotherapies are described in detail to address common challenges in cancer therapy, such as multidrug resistance, hypoxia, and metastasis. Finally, this review opens new insights into the design of multimodal synergistic therapies for potential future clinical applications of Bi-based NMs.

Ultrafast Synthesizing Bismuth Mesoporous Nanolitchi Radiosensitizer Loading High Dose DOX for CT-Guided Enhanced Chemoradiotherapy

Radiotherapy and chemotherapy are both common clinical treatment methods. The combination of the two treatments can decrease tumor recurrence. In this study, bismuth-based mesoporous litchi-shaped Na_0.2Bi_0.8O_0.35F_1.91:20%Yb (NBOF) nanoparticles (NPs) have been reported as a radiosensitizer and as a nanovehicle for loading and slow-releasing doxorubicin (DOX). After assembling with amphiphilic poly(ethylene glycol) (PEG), NBOF-DOX-PEG qualified with excellent aqueous dispersibility and the enhanced tumor radiation and chemo-synergistic therapy characteristics. The formation of NBOF revealed the oxygen element in NBOF came from H₂O and air in the synthesis and post-treatment process, and the size of NBOF could be adjusted by changing the concentration of doped Yb ion. The average size of NBOF was ca. 80 nm. Brunauer-Emmett-Teller results demonstrated the mesoporous structure of NBOF. So DOX could be loaded in NBOF and the optimized loading content was 39%. Then, NBOF-PEG exhibited a strong computed tomography signal whitening ability and enhanced radiotherapy effect. Combined with the chemotherapy ability of DOX, NBOF-DOX-PEG NPs presented remarkable synergistic tumor elimination ability. Meanwhile, NBOF-DOX-PEG NPs qualified for excellent biosafety. Our study not only proved the combined chemo- and radiotherapy for enhancing therapeutic effect but also supplied a functional Bi-based mesoporous nanovehicle for constructing an intelligent theranostic platform.

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.

Designing of UCNPs@Bi@SiO2 Hybrid Theranostic Nanoplatforms for Simultaneous Multimodal Imaging and Photothermal Therapy

Herein, a novel multifunctional nanoplatform was designed toward multimodality imaging and photothermal therapy (PTT). It was found that Bi nanoparticles could grow in situ on the surface of NaYF₄:20%Yb,2%Er@NaYF₄:40%Yb@NaGdF₄ core-shell nanoparticles (labeled as UCNPs). In this structure, UCNPs were mainly employed as an upconversion luminescence (UCL) imaging agent, whereas the Bi nanoparticles worked as an effective CT imaging and photothermal agent. Importantly, a dense SiO₂ shell was employed to protect the Bi nanoparticles from oxidation, and it also endowed the nanoplatform with excellent hydrophilic ability. The effective UCL/CT imaging and PTT performances were emphasized by a series of in vivo experiments, which suggest that the integrated nanoplatform with imaging and therapy functions shows great promise in the biomedical field.