A Short Review on Biomedical Applications of Nanostructured Bismuth Oxide and Related Nanomaterials

Anchoring Atomically Precise Chiral Bismuth Oxido Nanoclusters on Gold: The Role of Amino Acid Linkers

The adsorption of chiral molecules onto metallic surfaces triggers electron spin polarization at the interface, paving the way for applications in chiral opto-spintronics. However, the spin effects sensitively depend on the binding and ordering of the chiral species on surfaces. This study explores the adsorption of chiral thioether-functionalized atomically precise bismuth oxido nanoclusters (BiO-NCs) on gold (Au) surfaces, extending the conventional approach of using thiol-containing molecules and complexes to nanoclusters. Starting from the precursor [Bi38O45(NO3)20(dmso)28](NO3)4·4dmso (A), chiral BiO-NCs were synthesized by substituting the nitrates with N-(tert-butoxycarbonyl)-l-methionine (Boc-l-Met-O-) ligands to obtain [Bi38O45(Boc-l-Met-O)24] (2). The full exchange of nitrate by the Boc-l-methionine ligand was demonstrated by powder X-ray diffractograms, dynamic light scattering, electrospray ionization mass spectrometry, nuclear magnetic resonance, infrared, circular dichroism, and X-ray photoelectron spectroscopy. Compared to previously reported [Bi38O45(Boc-l-Phe-O)24(dmso)9] (1), BiO-NC 2 shows differences in the growth mode on a Au surface as revealed by scanning electron microscopy, wherefore a stronger binding of BiO-NC 2 is assumed. Anchoring of BiO-NC 2 to the Au surface through thioether groups induced a discernible change in the optical response of the Au surface analyzed by spectroscopic ellipsometry (SE). From the numerical modeling of the SE parameters, a layer thickness of ∼2 nm, corresponding to a monolayer of BiO-NC 2, was estimated for the samples prepared by dip coating. Thus, strong adsorption of BiO-NC 2 to the Au surface is concluded, which is an essential prerequisite for chiral-induced interface spin polarization.

Characterization of multifunctional β-cyclodextrin-coated Bi2O3 nanoparticles conjugated with curcumin for CT imaging-guided synergetic chemo-radiotherapy in breast cancer

Nanotechnology-based diagnostic, and therapeutic approaches revolutionized the field of cancer detection, and treatment, offering tremendous potential for cost-effective interventions in the early stages of disease. This research synthesized bismuth oxide (Bi2O3) nanoparticles (NPs) that were modified with polycyclodextrin (PCD), and functionalized with glucose (Glu) to load curcumin (CUR) for CT imaging and chemo-radiotherapy applications in Breast Cancer. The prepared Bi2O3@PCD-CUR-Glu NPs underwent comprehensive characterization, encompassing various aspects, including cell migration, cytotoxicity, cellular uptake, blood compatibility, reactive oxygen species (ROS) generation ability, real-time PCR analysis, in-vivo safety assessment, in-vivo anti-tumor efficacy, as well as in-vitro CT contrast and X-ray RT enhancement evaluation. CT scan was conducted before and after (1 and 3 h) intravenous injection of Bi2O3@PCD-CUR-Glu NPs. Through the use of coupled plasma optical emission spectrometry (ICP-OES) analysis, the final prepared nanoparticle distribution in the Bab/c mice was assessed. The spherical NPs that were ultimately synthesized and had a diameter of around 80 nm demonstrated exceptional toxicity towards the SKBr-3 breast cancer cell line. The cell viability was at its lowest level after 48 h of exposure to a radiation dose of 2 Gy at a concentration of 100 µg/mL. The combined treatment involving using Bi2O3@PCD-CUR-Glu NPs along with X-ray radiation showed a substantial increase in the generation of ROS, specifically a remarkable 420 % growth. Gene expression analysis indicated that the expression levels of P53, and BAX pro-apoptotic genes were significantly increased. The in-vitro CT imaging analysis conducted unequivocally demonstrated the notable superiority of NPs over Omnipaque in terms of X-ray absorption capacity, a staggering 1.52-fold increase at 80 kVp. The resultsdemonstrated that the targeted Bi2O3@PCD-CUR-Glu NPs could enhance the visibility of a small mice tumor that is detectable by computed tomography and made visible through X-ray attenuation. Results suggested that Bi2O3@PCD-CUR-Glu NPs, integrated with CT imaging and chemo-radiotherapy, have great potential as a versatile theranostic system for clinical application.

Red blood membrane camouflaging Bismuth nanoflowers designed for radio-photothermal therapy in lung cancer

Radio-photothermal therapy is an effective modality for cancer treatment. To overcome the radio-resistance in the hypoxic microenvironment and improve the sensitivity of radiotherapy, metal nanoparticles, and radio-photothermal therapy are widely used in the research of improving the curative effect and reducing the side effects of radiotherapy. Here, we developed red blood membrane camouflaging bismuth nanoflowers (RBCM-BNF) with outstanding physiological stability and biodegradability for lung tumours. In vitro data proved that the RBCM-BNF had the greatest cancer cell-killing ability combined with X-ray irradiation and photo-thermal treatment. Meanwhile, in vivo studies revealed that RBCM-BNF can alleviate the hypoxic microenvironment and promote tumour cell apoptosis by inhibiting HIF-1α expression and increasing caspase-3 expression. Therefore, RBCM-BNF had a good radio-sensitising effect and might be a promising biomimetic nanoplatform as a therapeutic target for cancer.

XRCC1: a potential prognostic and immunological biomarker in LGG based on systematic pan-cancer analysis

X-ray repair cross-complementation group 1 (XRCC1) is a pivotal contributor to base excision repair, and its dysregulation has been implicated in the oncogenicity of various human malignancies. However, a comprehensive pan-cancer analysis investigating the prognostic value, immunological functions, and epigenetic associations of XRCC1 remains lacking. To address this knowledge gap, we conducted a systematic investigation employing bioinformatics techniques across 33 cancer types. Our analysis encompassed XRCC1 expression levels, prognostic and diagnostic implications, epigenetic profiles, immune and molecular subtypes, Tumor Mutation Burden (TMB), Microsatellite Instability (MSI), immune checkpoints, and immune infiltration, leveraging data from TCGA, GTEx, CELL, Human Protein Atlas, Ualcan, and cBioPortal databases. Notably, XRCC1 displayed both positive and negative correlations with prognosis across different tumors. Epigenetic analysis revealed associations between XRCC1 expression and DNA methylation patterns in 10 cancer types, as well as enhanced phosphorylation. Furthermore, XRCC1 expression demonstrated associations with TMB and MSI in the majority of tumors. Interestingly, XRCC1 gene expression exhibited a negative correlation with immune cell infiltration levels, except for a positive correlation with M1 and M2 macrophages and monocytes in most cancers. Additionally, we observed significant correlations between XRCC1 and immune checkpoint gene expression levels. Lastly, our findings implicated XRCC1 in DNA replication and repair processes, shedding light on the precise mechanisms underlying its oncogenic effects. Overall, our study highlights the potential of XRCC1 as a prognostic and immunological pan-cancer biomarker, thereby offering a novel target for tumor immunotherapy.

Electromechanical and biological evaluations of 0.94Bi0.5Na0.5TiO3-0.06BaTiO3 as a lead-free piezoceramic for implantable bioelectronics

Smart implantable electronic medical devices are being developed to deliver healthcare that is more connected, personalised, and precise. Many of these implantables rely on piezoceramics for sensing, communication, energy autonomy, and biological stimulation, but the piezoceramics with the strongest piezoelectric coefficients are almost exclusively lead-based. In this article, we evaluate the electromechanical and biological characteristics of a lead-free alternative, 0.94Bi0.5Na0.5TiO3-0.06BaTiO3 (BNT-6BT), manufactured via two synthesis routes: the conventional solid-state method (PIC700) and tape casting (TC-BNT-6BT). The BNT-6BT materials exhibited soft piezoelectric properties, with d33 piezoelectric coefficients that were inferior to commonly used PZT (PIC700: 116 pC/N; TC-BNT-6BT: 121 pC/N; PZT-5A: 400 pC/N). The material may be viable as a lead-free substitute for soft PZT where moderate performance losses up to 10 dB are tolerable, such as pressure sensing and pulse-echo measurement. No short-term harmful biological effects of BNT-6BT were detected and the material was conducive to the proliferation of MC3T3-E1 murine preosteoblasts. BNT-6BT could therefore be a viable material for electroactive implants and implantable electronics without the need for hermetic sealing.

Engineering Analysis of Non-Braided Polycaprolactone Bioresorbable Flow Diverters for Aneurysms

This paper reports a nonbraided, bioresorbable polycaprolactone (PCL) flow diverter (FD) for the endovascular treatment of aneurysms. Bioresorbable FDs can reduce the risk associated with the permanent metallic FDs as they are resorbed by the body after curing of aneurysms. PCL FDs were designed and fabricated using an in-house hybrid electromelt spinning-fused deposition fabrication unit. Flow diverter's properties, surface qualities, and mechanical characteristics of PCL FDs of 50%, 60%, and 70% porosities were studied using scanning electron microscope (SEM), atomic force microscopy (AFM), and high precision universal testing machine (UTM). The deployability through a clinically relevant catheter was demonstrated in a PDMS aneurysm model. The angiographic visibility of the developed PCL FDs was evaluated using BaSO4 and Bi2O3 coatings of various concentration. The average strut thicknesses were 74.12 ± 6.63 μm, 63.07 ± 1.26 μm, and 56.82 ± 2.09 μm for PCL FDs with 50%, 60%, and 70% porosities, respectively. They average pore areas for the 50%, 60% and 70% porosities FDs were 0.055 ± 0.0056 mm2, 0. 0605 ± 0.0065 mm2, and 0.0712 ± 0.012 mm2, respectively. The surface quality was great with an RMS roughness value of 14.45 nm. The tensile, radial strength, and flexibility were found to be satisfactory and comparable to the nonbraided coronary stents. The developed PCL FDs were highly flexible and demonstrated to be deployable through conventional delivery system as low as 4 Fr catheters in a PDMS aneurysm model. The visibility under X-ray increases with the increasing concentration of coating materials BaSO4 and Bi2O3. The visibility intensity was slightly higher with Bi2O3 coating of PCL FDs. The overall results of the engineering analysis of the developed nonbraided PCL FDs are promising.

Synthesis, Characterization and Antimicrobial Activity of Multiple Morphologies of Gold/Platinum Doped Bismuth Oxide Nanostructures

Bismuth oxides were synthesized from bismuth carbonate using the sol-gel method. Studies have described the formation of Bi2O3, as a precursor of HNO3 dissolution, and intermediate oxides, such as BixOy when using H2SO4 and H3PO4. The average size of the crystallite calculated from Scherrer's formula ranged from 9 to 19 nm, according to X-ray diffraction. The FTIR analysis showed the presence of specific Bi2O3 bands when using HNO3 and of crystalline phases of "bismuth oxide sulphate" when using H2SO4 and "bismuth phosphate" when using H3PO4. The TG curves showed major mass losses and specific thermal effects, delimited in four temperature zones for materials synthesized with HNO3 (with loss of mass between 24% and 50%) and H2SO4 (with loss of mass between 45% and 76%), and in three temperature zones for materials synthesized with H3PO4 (with loss of mass between 13% and 43%). Further, the thermal stability indicates that materials have been improved by the addition of a polymer or polymer and carbon. Confocal laser scanning microscopy showed decreased roughness in the series, [BixOy]N > [BixOy-6% PVA]N > [BixOy-C-6% PVA]N, and increased roughness for materials [BixOy]S, [BixOy-6% PVA]S, [BixOy-C-6% PVA]S, [BixOy]P, [BixOy-6% PVA]P and [BixOy-C-6% PVA]P. The morphological analysis (electronic scanning microscopy) of the synthesized materials showed a wide variety of forms: overlapping nanoplates ([BixOy]N or [BixOy]S), clusters of angular forms ([BixOy-6% PVA]N), pillars ([BixOy-6% PVA]S-Au), needle particles ([BixOy-Au], [BixOy-6% PVA]S-Au, [BixOy-C-6% PVA]S-Au), spherical particles ([BixOy-C-6% PVA]P-Pt), 2D plates ([BixOy]P-Pt) and 3D nanometric plates ([BixOy-C-6% PVA]S-Au). For materials obtained in the first synthesis stage, antimicrobial activity increased in the series [BixOy]N > [BixOy]S > [BixOy]P. For materials synthesized in the second synthesis stage, when polymer (polyvinyl alcohol, PVA) was added, maximum antimicrobial activity, regardless of the microbial species tested, was present in the material [BixOy-6% PVA]S. For the materials synthesized in the third stage, to which graphite and 6% PVA were added, the best antimicrobial activity was in the material [BixOy-C-6% PVA]P. Materials synthesized and doped with metal ions (gold or platinum) showed significant antimicrobial activity for the tested microbial species.

Comparative Study of Bi2 O3 , MgO and ZrO2 Nanomaterials designed by Polymer Sacrificial Method for Amoxicillin delivery and Bone Regeneration: In-Vitro Studies.. [DOI: 10.21203/rs.3.rs-3146890/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Hard tissue scientists face many difficulties, including persistent osteomyelitis and diseased bone abnormalities. Inorganic mesoporous nanomaterials are excellent candidates for the adsorption and loading of bioactive medicinal substances because to their chemical-physical characteristics. Recently, zirconium oxide, magnesium oxide and bismuth oxide nanoparticles are of great surface area and biocompatibility, and they have been described as a new drug delivery carrier. In this study, amoxicillin antibiotic was loaded into the prepared mesoporous nanomaterials (ZrO2, MgO and Bi2O3) to form a local antibiotic delivery system. The prepared mesoporous nanomaterials were investigated by XRD, FTIR, TEM, zeta potential and BET surface area measurements. Amoxicillin antibiotic was released from the prepared mesoporous nanomaterials in PBS. The effectiveness of the antibacterial study against several gram-positive and gram-negative bacterial strains was assessed. The cytotoxicity study of the human osteoblast-like cells (MG-63) was tested for all prepared mesoporous nanomaterials utilizing MTT assay. ZrO2 demonstrated particle diameters in the range of (5.26– 11.47nm), MgO was (70–80nm) and Bi2O3 was (9.79– 13.7nm). The greater surface area was confirmed for Bi2O3 sample (3.99 m2g− 1) by BET surface area. Amoxicillin loaded mesoporous nano powders exhibited impressive antibacterial and antifungal activities. MgO and Bi2O3 mesoporous nanoparticles exhibited better antimicrobial activities compared to ZrO2 sample. The proliferation for all samples gave good results especially for MgO and Bi2O3. As a result, the produced mesoporous nanomaterials have a significant potential for use as medicine delivery systems for bone regeneration and for enhancing the properties of other products in medical applications.

The role of bismuth nanoparticles in the inhibition of bacterial infection

Bismuth (Bi) combinations have been utilized for the treatment of bacterial infections. In addition, these metal compounds are most frequently utilized for treating gastrointestinal diseases. Usually, Bi is found as bismuthinite (Bi sulfide), bismite (Bi oxide), and bismuthite (Bi carbonate). Newly, Bi nanoparticles (BiNP) were produced for CT imaging or photothermal treatment and nanocarriers for medicine transfer. Further benefits, such as increased biocompatibility and specific surface area, are also seen in regular-size BiNPs. Low toxicity and ecologically favorable attributes have generated interest in BiNPs for biomedical approaches. Moreover, BiNPs offer an option for treating multidrug-resistant (MDR) bacteria because they communicate directly with the bacterial cell wall, induce adaptive and inherent immune reactions, generate reactive oxygen compounds, limit biofilm production, and stimulate intracellular impacts. In addition, BiNPs in amalgamation with X-ray therapy as well as have the capability to treat MDR bacteria. BiNPs as photothermal agents can realize the actual antibacterial through continuous efforts of investigators in the near future. In this article, we summarized the properties of BiNPs, and different preparation methods, also reviewed the latest advances in the BiNPs' performance and their therapeutic effects on various bacterial infections, such as Helicobacter pylori, Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli.

Surface Modification of Bi2O3 Nanoparticles with Biotinylated β-Cyclodextrin as a Biocompatible Therapeutic Agent for Anticancer and Antimicrobial Applications

Bismuth oxide nanoparticles with appropriate surface chemistry exhibit many interesting properties that can be utilized in a variety of applications. This paper describes a new route to the surface modification of bismuth oxide nanoparticles (Bi₂O₃ NPs) using functionalized beta-Cyclodextrin (β-CD) as a biocompatible system. The synthesis of Bi₂O₃ NP was done using PVA (poly vinyl alcohol) as the reductant and the Steglich esterification procedure for the functionalization of β-CD with biotin. Ultimately, the Bi₂O₃ NPs are modified using this functionalized β-CD system. The particle size of the synthesized Bi₂O₃ NPs is found to be in the range of 12-16 nm. The modified biocompatible systems were characterized using different characterization techniques such as Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray powder diffraction (XRD) and Differential Scanning Calorimetric analysis (DSC). Additionally, the antibacterial and anticancerous effects of the surface-modified Bi₂O₃ NP system were also investigated.

Rapid synthesis of bismuth-organic frameworks as selective antimicrobial materials against microbial biofilms

Antibiotic resistance is a global public health threat, and urgent actions should be undertaken for developing alternative antimicrobial strategies and approaches. Notably, bismuth drugs exhibit potent antimicrobial effects on various pathogens and promising efficacy in tackling SARS-CoV-2 and related infections. As such, bismuth-based materials could precisely combat pathogenic bacteria and effectively treat the resultant infections and inflammatory diseases through a controlled release of Bi ions for targeted drug delivery. Currently, it is a great challenge to rapidly and massively manufacture bismuth-based particles, and yet there are no reports on effectively constructing such porous antimicrobial-loaded particles. Herein, we have developed two rapid approaches (i.e., ultrasound-assisted and agitation-free methods) to synthesizing bismuth-based materials with ellipsoid- (Ellipsoids) and rod-like (Rods) morphologies respectively, and fully characterized physicochemical properties. Rods with a porous structure were confirmed as bismuth metal-organic frameworks (Bi-MOF) and aligned with the crystalline structure of CAU-17. Importantly, the formation of Rods was a 'two-step' crystallization process of growing almond-flake-like units followed by stacking into the rod-like structure. The size of Bi-MOF was precisely controlled from micro-to nano-scales by varying concentrations of metal ions and their ratio to the ligand. Moreover, both Ellipsoids and Rods showed excellent biocompatibility with human gingival fibroblasts and potent antimicrobial effects on the Gram-negative oral pathogens including Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis and Fusobacterium nucleatum. Both Ellipsoids and Rods at 50 ​μg/mL could disrupt the bacterial membranes, and particularly eliminate P. gingivalis biofilms. This study demonstrates highly efficient and facile approaches to synthesizing bismuth-based particles. Our work could enrich the administration modalities of metallic drugs for promising antibiotic-free healthcare.

Low temperature energy- efficient synthesis methods for bismuth-based nanostructured photocatalysts for environmental remediation application: A review

Bismuth-based composite materials have unique structural, chemical, optical, and electrical properties that are highly beneficial in Photocatalysis. The layered structure and tunable bandgap properties of the Bismuth-based composites are advantageous for the absorption of solar light efficiently. Also, these properties help the separation and recombination of photogenerated charge carriers, leading to enhancement in the photocatalytic activity. Synthesis of the catalyst at a lower temperature to produce catalyst reduces the production cost and electrical energy consumption. This review provides an overview of the recent development in Bismuth-based composite nanostructured photocatalytic materials, mainly using low-temperature driven synthesis methods. Herein, we have mainly summarized the primarily used low temperature-based synthetic routes, particularly in the temperature range of 50-300 °C for synthesizing Bismuth-based composite materials. In addition to this, the photocatalytic mechanism, the textural, structural, electronic, and photocatalytic properties of the synthesized photocatalysts are discussed. The literature shows that the surface area of the composite Bismuth-based photocatalytic materials synthesized using the low-temperature synthetic route is in the range of 1.5-81 m²/g and can be activated by solar, ultraviolet, and Light Emitting Diode (LEDs) light irradiation based on the synthetic route. Their photocatalytic performance and structural stability are excellent and utilized for several runs. The comprehensive understanding of the low-temperature synthesis of Bismuth-based composite materials for visible light-activated photocatalytic applications provided will be useful for developing photocatalytic materials on an industrial scale due to energy-efficient synthetic routes. Furthermore, the prospects of low temperature-driven Bismuth-based composite synthesis routes are discussed.

Deposition of Nanosized Amino Acid Functionalized Bismuth Oxido Clusters on Gold Surfaces

Bismuth compounds are of growing interest with regard to potential applications in catalysis, medicine, and electronics, for which their environmentally benign nature is one of the key factors. One thing that currently hampers the further development of bismuth oxido-based materials, however, is the often low solubility of the precursors, which makes targeted immobilisation on substrates challenging. We present an approach towards the solubilisation of bismuth oxido clusters by introducing an amino carboxylate as a functional group. For this purpose, the bismuth oxido cluster [Bi38O45(NO3)20(dmso)28](NO3)4·4dmso (dmso = dimethyl sulfoxide) was reacted with the sodium salt of tert-butyloxycabonyl (Boc)-protected phenylalanine (L-Phe) to obtain the soluble and chiral nanocluster [Bi38O45(Boc–Phe–O)24(dmso)9]. The exchange of the nitrates by the amino carboxylates was proven by nuclear magnetic resonance, Fourier-transform infrared spectroscopy, as well as elemental analysis and X-ray photoemission spectroscopy. The solubility of the bismuth oxido cluster in a protic as well as an aprotic polar organic solvent and the growth mode of the clusters upon spin, dip, and drop coating on gold surfaces were studied by a variety of microscopy, as well as spectroscopic techniques. In all cases, the bismuth oxido clusters form crystalline agglomerations with size, height, and distribution on the substrate that can be controlled by the choice of the solvent and of the deposition method.

Guayule Natural Rubber Latex and Bi2O3 Films for X-ray Attenuating Medical Gloves

Existing natural latex radiation-attenuating gloves (RAGs) contain a high loading of radiation attenuation filler that reduces their mechanical properties to below Food and Drug Administration (FDA) medical glove requirements. RAGs are commonly formulated using Hevea natural rubber latex and lead-based fillers. The former can cause life-threatening allergic responses and the latter are known for their toxicity. In this work, a new lead-free RAG formulation based on circumallergenic guayule natural rubber latex (GNRL) and non-toxic radiation attenuation filler bismuth trioxide (Bi₂O₃) was developed. GNRL films with Bi₂O₃ loadings ranging from 0 to 300 PHR at different thicknesses were prepared. Radiation attenuation efficiencies (AE) at 60, 80, 100, and 120 kVp were determined and attenuation isocontour curves predicted film thickness and Bi₂O₃ loading required to meet or exceed the radiation attenuation requirements of ASTM D7866 and commercial RAGs. Optimal curing conditions for GNRL/Bi₂O₃ films with 150 PHR Bi₂O₃ were investigated by varying curing temperatures and time from 87 °C to 96 °C and 65 min to 90 min, respectively. In general, as the loading of the filler increased, the density of the films increased while the thickness decreased. GNRL/Bi₂O₃ films with 150 PHR Bi₂O₃ and 0.27 mm provided 5% more AE than RAG market average attenuation at the same thickness. The films with 150 PHR Bi₂O₃ cured under near-optimal conditions (90 °C/85 min, and 87 °C/65 min) met both the radiation attenuation standard (ASTM D7866) and the natural latex surgeon and examination glove standards (ASTM D3577 and D3578, respectively). Thus, gloves made using our formulations and protocols demonstrated potential to meet and surpass medical natural latex glove standards, offer a single product for both infection control and radiation protection instead of double-gloving, provide a greater degree of comfort to the user, and simultaneously reduce contact reactions and eliminate potential latex allergic reaction.

Electrodes for Paracetamol Sensing Modified with Bismuth Oxide and Oxynitrate Heterostructures: An Experimental and Computational Study

In this work, novel platforms for paracetamol sensing were developed by the deposition of Bi2O3, Bi5O7NO3 and their heterostructures onto screen-printed carbon-paste electrodes. An easy and scalable solid state synthesis route was employed, and by setting the calcination temperatures at 500 °C and 525 °C we induced the formation of heterostructures of Bi2O3 and Bi5O7NO3. Cyclic voltammetry measurements highlighted that the heterostructure produced at 500 °C provided a significant enhancement in performance compared to the monophases of Bi2O and Bi5O7NO3, respectively. That heterostructure showed a mean peak-to-peak separation Ep of 411 mV and a sensitivity increment of up to 70% compared to bare electrodes. A computational study was also performed in order to evaluate the geometrical and kinetic parameters of representative clusters of bismuth oxide and subnitrate when they interact with paracetamol.

Effect of Tantalum Pentoxide Addition on the Radiopacity Performance of Bi2O3/Ta2O5 Composite Powders Prepared by Mechanical Milling

Among the various phases of bismuth oxide, the high temperature metastable face-centered cubic δ phase attracts great attention due to its unique properties. It can be used as an ionic conductor or an endodontic radiopacifying material. However, no reports concerning tantalum and bismuth binary oxide prepared by high energy ball milling and serving as a dental radiopacifier can be found. In the present study, Ta₂O₅-added Bi₂O₃ composite powders were mechanically milled to investigate the formation of these metastable phases. The as-milled powders were examined by X-ray diffraction and scanning electron microscopy to reveal the structural evolution. The as-milled composite powders then served as the radiopacifier within mineral trioxide aggregates (i.e., MTA). Radiopacity performance, diametral tensile strength, setting times, and biocompatibility of MTA-like cements solidified by deionized water, saline, or 10% calcium chloride solution were investigated. The experimental results showed that subsequent formation of high temperature metastable β-Bi_7.8Ta_0.2O_12.2, δ-Bi₂O₃, and δ-Bi₃TaO₇ phases can be observed after mechanical milling of (Bi₂O₃)₉₅(Ta₂O₅)₅ or (Bi₂O₃)₈₀(Ta₂O₅)₂₀ powder mixtures. Compared to its pristine Bi₂O₃ counterpart with a radiopacity of 4.42 mmAl, long setting times (60 and 120 min for initial and final setting times) and 84% MG-63 cell viability, MTA-like cement prepared from (Bi₂O₃)₉₅(Ta₂O₅)₅ powder exhibited superior performance with a radiopacity of 5.92 mmAl (the highest in the present work), accelerated setting times (the initial and final setting time can be shortened to 25 and 40 min, respectively), and biocompatibility (94% cell viability).

Special Issue "Metal and Metal Oxide Nanoparticles: Design, Characterization, and Biomedical Applications"

The current Special Issue entitled "Metal and Metal Oxide Nanoparticles: Design, Characterization, and Biomedical Applications" aims to present contributions from all scientists producing and/or applying metal and metal oxide nanoparticles in a diagnostic, therapeutic or theranostics context [...].

Rapid Fabrication of MgNH4PO4·H2O/SrHPO4 Porous Composite Scaffolds with Improved Radiopacity via 3D Printing Process

Although bone repair scaffolds are required to possess high radiopacity to be distinguished from natural bone tissues in clinical applications, the intrinsic radiopacity of them is usually insufficient. For improving the radiopacity, combining X-ray contrast agents with bone repair scaffolds is an effective method. In the present research, MgNH₄PO₄·H₂O/SrHPO₄ 3D porous composite scaffolds with improved radiopacity were fabricated via the 3D printing technique. Here, SrHPO₄ was firstly used as a radiopaque agent to improve the radiopacity of magnesium phosphate scaffolds. X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS) were used to characterize the phases, morphologies, and element compositions of the 3D porous composite scaffolds. The radiography image showed that greater SrHPO₄ contents corresponded to higher radiopacity. When the SrHPO₄ content reached 9.34%, the radiopacity of the composite scaffolds was equal to that of a 6.8 mm Al ladder. The porosity and in vitro degradation of the porous composite scaffolds were studied in detail. The results show that magnesium phosphate scaffolds with various Sr contents could sustainably degrade and release the Mg, Sr, and P elements during the experiment period of 28 days. In addition, the cytotoxicity on MC3T3-E1 osteoblast precursor cells was evaluated, and the results show that the porous composite scaffolds with a SrHPO₄ content of 9.34% possessed superior cytocompatibility compared to that of the pure MgNH₄PO₄·H₂O scaffolds when the extract concentration was 0.1 g/mL. Cell adhesion experiments showed that all of the scaffolds could support MC3T3-E1 cellular attachment well. This research indicates that MgNH₄PO₄·H₂O/SrHPO₄ porous composite scaffolds have potential applications in the bone repair fields.

Facile Synthesis of Zn-Doped Bi2O3 Nanoparticles and Their Selective Cytotoxicity toward Cancer Cells

Bismuth (III) oxide nanoparticles (Bi2O3 NPs) have shown great potential for biomedical applications because of their tunable physicochemical properties. In this work, pure and Zn-doped (1 and 3 mol %) Bi2O3 NPs were synthesized by a facile chemical route and their cytotoxicity was examined in cancer cells and normal cells. The X-ray diffraction results show that the tetragonal phase of β-Bi2O3 remains unchanged after Zn-doping. Transmission electron microscopy and scanning electron microscopy images depicted that prepared particles were spherical with smooth surfaces and the homogeneous distribution of Zn in Bi2O3 with high-quality lattice fringes without distortion. Photoluminescence spectra revealed that intensity of Bi2O3 NPs decreases with increasing level of Zn-doping. Biological data showed that Zn-doped Bi2O3 NPs induce higher cytotoxicity to human lung (A549) and liver (HepG2) cancer cells as compared to pure Bi2O3 NPs, and cytotoxic intensity increases with increasing concentration of Zn-doping. Mechanistic data indicated that Zn-doped Bi2O3 NPs induce cytotoxicity in both types of cancer cells through the generation of reactive oxygen species and caspase-3 activation. On the other hand, biocompatibility of Zn-doped Bi2O3 NPs in normal cells (primary rat hepatocytes) was greater than that of pure Bi2O3 NPs and biocompatibility improves with increasing level of Zn-doping. Altogether, this is the first report highlighting the role of Zn-doping in the anticancer activity of Bi2O3 NPs. This study warrants further research on the antitumor activity of Zn-doped Bi2O3 NPs in suitable in vivo models.

Defective Bismuth Oxide as Effective Adsorbent for Arsenic Removal from Water and Wastewater

In this work, we report solid-state synthetized defective Bi₂O₃ containing Bi(V) sites as effective and recyclable arsenic adsorbent materials. Bi₂O₃ was extensively characterized, and structure-related adsorption processes are reported. Both As(V) and As(III) species-adsorption processes were investigated in a wide range of concentrations, pH values, and times. The effect of several competing ions was also tested together with the adsorbent recyclability.

A Review on Recent Advancements of Graphene and Graphene-Related Materials in Biological Applications

Graphene is the most outstanding material among the new nanostructured carbonaceous species discovered and produced. Graphene’s astonishing properties (i.e., electronic conductivity, mechanical robustness, large surface area) have led to a deep change in the material science field. In this review, after a brief overview of the main characteristics of graphene and related materials, we present an extensive overview of the most recent achievements in biological uses of graphene and related materials.

Radiopacity quantification and spectroscopic characterization of OrthoMTA and RetroMTA

The aim of this article was to investigate the unknown radiopacity performances of OrthoMTA and RetroMTA via means of a contemporary image analyzing methods and energy dispersive X-ray spectroscopy. Three commercial hydraulic calcium silicate-based cements and a calcium hydroxide-based paste were used. Pure-grade zirconium oxide, bismuth oxide, zinc oxide, barium sulfate, and calcium hydroxide were as references. An energy-dispersive X-ray spectroscopy instrument was used for the elemental analysis. Radiographic image data was obtained according to the International Organization for Standardization 6876-2012 specifications. The region of interest was determined for each specimen. Mean (±SD) grey values of the X-ray image data was measured with an image analyzing software. The calibration curve was created by curve-plotting software and the mean grey-values were matched versus Al values (mm Al). Data were analyzed with one-way ANOVA followed by Tukey's multiple comparison test. Spectroscopic characterization of the commercial materials was shown with assigned Carbon, oxygen, aluminum, silicon, calcium, zinc, zirconium, barium, tungsten, bismuth, and sulfur elements. The major radiopacifier/s of OrthoMTA is Bi, of RetroMTA is Zr, of BioDentine are Ba and Zr, and of ProCal is Ba. The radiopacity values of all commercial materials are significantly different (p < .05). The rank of the radiopacity values: RetroMTA (3.36 ± 0.29mmAl) > OrthoMTA (2.56 ± 0.19mmAl) > BioDentine (2.02 ± 0.12mmAl) > ProCal (1.46 ± 0.60mmAl). The study reported that the radiopacity values and spectral characterization of RetroMTA and OrthoMTA cements. The pixel-based and reproducible method could be used universally to the quantification of the radiodensity of digitally collected X-ray data.