The Emerging Roles of Silver Nanoparticles to Target Viral Life Cycle and Detect Viral Pathogens

Along the line of recent vaccine advancements, new antiviral therapeutics are compelling to combat viral infection-related public health crises. Several properties of silver nanoparticles (AgNPs) such as low level of cytotoxicity, ease of tunability of the AgNPs in the ultra-small nanoscale size and shape through different convenient bottom-up chemistry approaches, high penetration of the composite with drug formulations into host cells has made AgNPs, a promising candidate for developing antivirals. In this review, we have highlighted the recent advancements in the AgNPs based nano-formulations to target cellular mechanisms of viral propagation, immune modulation of the host, and the ability to synergistically enhance the activity of existing antiviral drugs. On the other hand, we have discussed the recent advancements on AgNPs based detection of viral pathogens from clinical samples using inherent physicochemical properties. This article will provide an overview of our current knowledge on AgNPs based formulations that has promising potential for developing a counteractive strategy against emerging and existing viruses.

Reversible Nanogate System for Mesoporous Silica Nanoparticles Based on Diels-Alder Adducts

The implementation of nanoparticles as nanomedicines requires sophisticated surface modifications to reduce the immune response and enhance recognition abilities. Mesoporous silica nanoparticles present extraordinary host-guest abilities and facile surface functionalization. These two factors make them ideal candidates for the development of novel drug-delivery systems, at the expense of increasing structural complexity. With this idea in mind, a system composed of triggerable and tunable silica nanoparticles was developed for application as drug-delivery nanocarriers. Diels-Alder cycloaddition adducts were chosen as thermal-responsive units that permitted the binding of gold nanocaps able to block the pores and allow the incorporation of targeting fragments. The capping efficiency was tested under different thermal conditions to give outstanding efficiencies within the physiological range and mild temperatures, as well as enhanced release under pulsing heating cycles, which showed the best release profiles.

Surfactant Effects on the Morphology and Pseudocapacitive Behavior of V2 O5 ⋅H2 O

To overcome the drawback of low electrical conductivity within supercapacitor applications, several surfactants are used for nanoscale V2 O5 to enhance the specific surface area. Polyethylene glycol 6000 (PEG-6000), sodium dodecylbenzene sulfonate (SDBS), and Pluronic P-123 (P123) controllers, if used as soft templates, easily form large specific surface area crystals. However, the specific mechanism through which this occurs and the influence of these surfactants is not clear for V2 O5 ⋅H2 O. In the present study, we aimed to investigate the mechanism of crystal growth through hydrothermal processes and the pseudocapacitive behavior of these crystals formed by using diverse surfactants, including PEG-6000, SDBS, and P123. Our results show that different surfactants can dramatically influence the morphology and capacitive behavior of V2 O5 ⋅H2 O powders. Linear nanowires, flower-like flakes, and curly bundled nanowires can be obtained because of electrostatic interactions in the presence of PEG-6000, SDBS, and P123, respectively. Furthermore, the electrochemical performance of these powders shows that the nanowires, which are electrodes mediated by PEG-6000, exhibit the highest capacitance of 349 F g(-1) at a scan rate of 5 mV s(-1) of all the surfactants studied. However, a symmetric P123 electrode comprising curly bundled nanowires with numerous nanopores showed an excellent and stable specific capacitance of 127 F g(-1) after 200 cycles. This work is beneficial to understanding the fundamental role of the surfactant in the assisted growth of V2 O5 ⋅H2 O and the resulting electrochemical properties of the pseudocapacitors, which could be useful for the future design of appropriate materials.

In Vivo Processing of Ceria Nanoparticles inside Liver: Impact on Free-Radical Scavenging Activity and Oxidative Stress

The cytotoxicity of ceria ultimately lies in its electronic structure, which is defined by the crystal structure, composition, and size. Despite previous studies focused on ceria uptake, distribution, biopersistance, and cellular effects, little is known about its chemical and structural stability and solubility once sequestered inside the liver. Mechanisms will be presented that elucidate the in vivo transformation in the liver. In vivo processed ceria reveals a particle-size effect towards the formation of ultrafines, which represent a second generation of ceria. A measurable change in the valence reduction of the second-generation ceria can be linked to an increased free-radical scavenging potential. The in vivo processing of the ceria nanoparticles in the liver occurs in temporal relation to the brain cellular and protein clearance responses that stem from the ceria uptake. This information is critical to establish a possible link between cellular processes and the observed in vivo transformation of ceria. The temporal linkage between the reversal of the pro-oxidant effect (brain) and ceria transformation (liver) suggests a cause-effect relationship.

Self-assembled fluorescent organic nanoparticles for live-cell imaging

Fluorescent, cell-permeable, organic nanoparticles based on self-assembled π-conjugated oligomers with high absorption cross-sections and high quantum yields have been developed. The nanoparticles are generated with a tuneable density of amino groups for charge-mediated cellular uptake by a straightforward self-assembly protocol, which allows for control over size and toxicity. The results show that a single amino group per ten oligomers is sufficient to achieve cellular uptake. The non-toxic nanoparticles are suitable for both one- and two-photon cellular imaging and flow cytometry, and undergo very efficient cellular uptake.

Morphological Phase Diagram of Biocatalytically Active Ceria Nanostructures as a Function of Processing Variables and Their Properties

We rationalize how fluorite-structured CeO₂ , which is crystallographically isotropic, can grow anisotropically (without templates) to form nanoparticles, rods, and cubes. In particular, single-crystalline and monodispersed cubic CeO₂ nanoparticles, nanorods, and nanocubes have been selectively synthesized by a very simple, efficient, and economical hydrothermal process using different NaOH concentrations, and Ce(NO₃ )₃ as the cerium precursor. High-resolution transmission electron microscopy reveals nanomaterials with differently exposed crystal planes: {111} and {100} for nanoparticles, {110} and {100} for nanorods, and {100} for nanocubes. During the preparation of the CeO₂ nanomaterials, the formation of intermediate anisotropic Ce(OH)₃ species under basic conditions and their conversion into CeO₂ at higher temperature are key factors responsible for the shape evolution. Atomistic computer simulations were used to help rationalize how the synthetic conditions impact upon the morphology of the nanomaterial. The synthesized CeO₂ nanoparticles and nanorods demonstrate higher catalase mimetic activities than the nanocubes.

Conjugation of transferrin to azide-modified CdSe/ZnS core-shell quantum dots using cyclooctyne click chemistry

Twinkle twinkle quantum dot: Conjugation of biomolecules to azide-modified quantum dots (QDs) through a bifunctional linker, using strain-promoted azide-alkyne cycloaddition with the QD and a squaramide linkage to the biomolecule (see scheme). Transferrin-conjugated QDs were internalized by transferrin-receptor expressing HeLa cells.