Antiviral effects of coinage metal-based nanomaterials to combat COVID-19 and its variants.

The world has been suffering from the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic, and millions of people have been infected through human-to-human transmission and lost their lives within months. Although multidisciplinary scientific approaches have been employed to fight against this deadly pandemic, various mutations and diverse environments keep producing constraints in treating SARS-CoV-2. Indeed, the efficacy of the developed vaccines has been limited, and inoculation with the vaccines does not guarantee complete protection even though multiple doses are required, which is a frustrating process. Historically, coinage metals (Cu, Ag, and Au) have been well-known for their effectiveness in antiviral action as well as good biocompatibility, binding receptor inhibition, reactive oxygen species, and phototherapy properties. Thus, this review highlights the diagnostic and therapeutic mechanisms of SARS-CoV-2 using the antivirus ability and mode of action of coinage metals such as viral entry mechanisms into host cells and the NP-inhibition process, which are explained in detail. This article also draws attention to coinage metal nanomaterial-based approaches to treat other contagious viruses. In addition, coinage metal-based biosensors and an overview of some other biocompatible metal-based nanomaterials to fight against SARS-CoV-2 variants are discussed. Finally, the advantages, perspectives and challenges of coinage metal nanoparticles are given to fight against viral infections in the future.

A biomineralized Prussian blue nanotherapeutic for enhanced cancer photothermal therapy.

Photothermal therapy is a promising tumor ablation technique that converts light into heat energy to kill cancer cells. Prussian blue (PB), a biocompatible photothermal reagent, has been widely explored for cancer treatment. However, the translational potential of PB is severely hampered by its low photothermal conversion efficiency (PCE) and poor stability. To tackle these issues, we adopted the biomineralization modality where PB was integrated with calcium phosphate (CaP) through the binding between calcium ions and PB. The mineralized PB (CaP&PB) demonstrated significantly improved PCE (40.2%), resulting from a calcium-induced bandgap-narrowing effect, and exhibited superior suspension stability. Using a 4T1 orthotopic breast cancer BALB/c mouse model, we observed that mineralized PB showed a significant temperature increase within the tumor, which led to better tumoricidal activity compared with CaP and PB when identical NIR treatment was applied. These achievements demonstrated the success of introducing calcium phosphate into Prussian blue by biomineralization to improve the PCE and stability of photothermal reagents, suggesting an alternative translational strategy for enhanced cancer photothermal therapy.

Facile synthesis of biocompatible magnetic titania nanorods for T1-magnetic resonance imaging and enhanced phototherapy of cancers.

Cancer treatment has been recently energized by nanomaterials that simultaneously offer diagnostic and therapeutic effects. Among the imaging and treatment modalities in frontline research today, magnetic resonance imaging (MRI) and phototherapy have gained significant interest due to their noninvasiveness among other intriguing benefits. Herein, Fe(iii) was adsorbed on titanium dioxide to develop magnetic Fe-TiO2 nanocomposites (NCs) which leverage the Fe moiety in a double-edge-sword approach to: (i) achieve T1-weighted MRI contrast enhancement, and (ii) improve the well-established photodynamic therapeutic efficacy of TiO2 nanoparticles. Interestingly, the proposed NCs exhibit classic T1 MRI contrast agent properties (r1 = 1.16 mM-1 s-1) that are comparable to those of clinically available contrast agents. Moreover, the NCs induce negligible cytotoxicity in traditional methods and show remarkable support to the proliferation of intestine organoids, an advanced toxicity evaluation system based on three-dimensional organoids, which could benefit their potential safe application for in vivo cancer theranostics. Aided by the Fenton reaction contribution of the Fe component of the Fe-TiO2 NCs, considerable photo-killing of cancer cells is achieved upon UV irradiation at very low (2.5 mW cm-2) intensity in typical cancer PDT. It is therefore expected that this study will guide the engineering of other biocompatible magnetic titania-based nanosystems with multi-faceted properties for biomedical applications.

A Hybrid Organo-Nanotheranostic Platform of Superlative Biocompatibility for Near-Infrared-Triggered Fluorescence Imaging and Synergistically Enhanced Ablation of Tumors.

The quest for an all-organic nanosystem with negligible cytotoxicity and remarkable in vivo tumor theranostic capability is inescapably unending. Hitherto, the landscape of available photothermal agents is dominated by metal-based nanoparticles (NPs) with attendant in vivo negatives. Here, an all-organic-composed theranostic nanosystem with outstanding biocompatibility for fluorescence image-guided tumor photothermal therapy, and as a potential alternative to metal-based photothermal agents is developed. This is rationally achieved by compartmentalizing indocyanine green (ICG) in glycol chitosan (GC)-polypyrrole (PP) nanocarrier to form hybrid ICG@GC-PP NPs (≈65 nm). The compartmentalization strategy, alongside the high photothermal conversion ability of PP jointly enhances the low photostability of free ICG. Advantageously, ICG@GC-PP is endowed with an impeccable in vivo performance by the well-known biocompatibility track records of its individual tri organo-components (GC, PP, and ICG). As a proof of concept, ICG@GC-PP NPs enables a sufficiently prolonged tumor diagnosis by fluorescence imaging up to 20 h post-injection. Furthermore, owing to the complementary heating performances of PP and ICG, ICG@GC-PP NPs-treated mice by one-time near-infrared irradiation exhibit total tumor regression within 14 days post-treatment. Therefore, leveraging the underlying benefits of this study will help to guide the development of new all-organic biocompatible systems in synergism, for safer tumor theranostics.

Tunable fabrication of new theranostic Fe3O4-black TiO2 nanocomposites: dual wavelength stimulated synergistic imaging-guided phototherapy in cancer.

The development of a simplified theranostic system with high-efficiency for multifunctional imaging-guided photodynamic therapy/photothermal therapy (PDT/PTT) is a great challenge. Therefore, a versatile fabrication strategy was introduced to design new Fe3O4-black TiO2 nanocomposites (Fe-Ti NCs). The Fe-Ti NCs exhibit an intense broad light absorption, high photothermal conversion efficiency, inherited phototherapy, and favorable magnetic resonance imaging (MRI) properties. The in vitro results demonstrate synergistic PTT and PDT capability of Fe-Ti NCs under 808 nm irradiation at low concentration and power density. Fe-Ti NCs also show superior phototherapy performance (PTT/PDT) under 671 nm laser irradiation. The confocal microscopy analysis demonstrates reactive oxygen species (ROS)-mediated synergistic phototherapy. Hematological and histological analysis confirms no evident toxicity of Fe-Ti NCs. The in vivo photoinduced tumor ablation capability of Fe-Ti NCs was assessed and monitored, and a rapid increase in temperature (60 ± 2 °C) after being exposed to 808 nm laser at 0.7 W cm-2 for 5 min was observed. Then, the same change in temperature is observed under 671 nm laser at 0.5 W cm-2. Thus, in vitro and in vivo dual-wavelength laser tumor ablation ability of Fe-Ti NCs verified excellent synergistic phototherapy efficacy against tumors. Moreover, Fe-Ti NCs exhibit superparamagnetic behavior, high magnetization value (48 emu g-1), good r2 relaxivity value (38.2 mM-1 s-1), and excellent T2 imaging capability to monitor therapeutic performance.

Lecithin-coated gold nanoflowers (GNFs) for CT scan imaging applications and biochemical parameters; in vitro and in vivo studies.

We report a novel strategy for the fabrication of lecithin-coated gold nanoflowers (GNFs) via single-step design for CT imaging application. Field-emission electron microscope confirmed flowers like morphology of the as-synthesized nanostructures. Furthermore, these show absorption peak in near-infrared (NIR) region at λmax 690 nm Different concentrations of GNFs are tested as a contrast agent in CT scans at tube voltage 135 kV and tube current 350 mA. These results are compared with same amount of iodine at same CT scan parameters. The results of in vitro CT scan study show that GNFs have good contrast enhancement properties, whereas in vivo study of rabbits CT scan shows that GNFs enhance the CT image clearly at 135 kV as compared to that of iodine. Cytotoxicity was studied and blood profile show minor increase of white blood cells and haemoglobin, whereas decrease of red blood cells and platelets.