Biomimetic Nanomaterial Strategies for Virus Targeting: Antiviral Therapies and Vaccines

The ongoing coronavirus disease 2019 (COVID-19) pandemic highlights the importance of developing effective virus targeting strategies to treat and prevent viral infections. Since virus particles are nanoscale entities, nanomaterial design strategies are ideally suited to create advanced materials that can interact with and mimic virus particles. In this progress report, the latest advances in biomimetic nanomaterials are critically discussed for combating viral infections, including in the areas of nanomaterial-enhanced viral replication inhibitors, biomimetic virus particle capture schemes, and nanoparticle vaccines. Particular focus is placed on nanomaterial design concepts and material innovations that can be readily developed to thwart future viral threats. Pertinent nanomaterial examples from the COVID-19 situation are also covered along with discussion of human clinical trial efforts underway that might lead to next-generation antiviral therapies and vaccines.     

Formation energies and site preference of substitutional divalent cations in carbonated apatite

First-principles calculations were performed to examine defect formation energies and site preference of substitutional divalent cations M²⁺ (M = Mg, Cu, Zn, Cd, Sr, Pb, and Ba) in hydroxyapatite (HAp, Ca₁₀(PO₄)₆(OH)₂) and carbonated apatite (CAp). All inequivalent substitutional sites of and M²⁺ were investigated to determine their most preferential sites. For all M²⁺ studied, their defect formation energies for the most stable substitutional sites were lower in CAp than in hydroxyapatite (HAp), demonstrating that M²⁺ are preferentially substituted into CAp over HAp. For Ca sites in CAp, correlations between the defect formation energies and Ca-O bond lengths showed that bigger and smaller M²⁺ than Ca²⁺ are preferentially substituted for Ca sites with longer and shorter bond lengths than those in HAp, respectively. In addition, Ca sites with lower coordination numbers than 6 are preferentially substituted by Zn²⁺ and Cu²⁺ that originally tend to form 4- or 5-fold coordination in their phosphate crystals. substitution is therefore likely to effectively stabilize substitutional foreign ions by modifying bond lengths and coordination numbers of Ca sites from those in pure HAp. These effects may play an important role in enhancing the M²⁺ solubility into CAp.     

Calibration method for a carbon nanotube field-effect transistor biosensor

An easy calibration method based on the Langmuir adsorption theory is proposed for a carbon nanotube field-effect transistor (NTFET) biosensor. This method was applied to three NTFET biosensors that had approximately the same structure but exhibited different characteristics. After calibration, their experimentally determined characteristics exhibited a good agreement with the calibration curve. The reason why the observed characteristics of these NTFET biosensors differed among the devices was that the carbon nanotube (CNT) that formed the channel was not uniform. Although the controlled growth of a CNT is difficult, it is shown that an NTFET biosensor can be easy calibrated using the proposed calibration method, regardless of the CNT channel structures.     

Measurements of the surface tension for R290, R600a and R290/R600a mixture

The surface tensions of R290, R600a and R290/R600a mixture have been measured by the modified differential capillary-rise method. Twenty-two data points for R290 and 21 data points for R600a were obtained in the temperature range between 273 K and 354 K, and 43 data points for R290/R600a mixture on three isotherms of 278 K, 300 K and 320 K were obtained. The experimental uncertainties of temperature and surface tension are estimated to be within 20 mK and 0.2 mN m⁻¹, respectively. Surface tension correlations as a function of temperature for pure R290 and R600a were formulated in the temperature range between 253 K and critical temperature, and the correlation as a function of the composition for R290/R600a mixture was discussed at 278 K, 300 K and 320 K. It is found that the surface tension for R290/R600a mixture can be reproduced by the simple mixing rule by mole fraction with the correlations of both pure components.     

Radical polymerization of (phenylethynyl)styrenes and characterization of poly(phenylethynyl)styrenes as a thermally curable material

Summary The radical polymerizations of 2-, 3-, and 4-(phenylethynyl)styrenes (1a–c) and the copolymerizations of 1a–c (M₁) with styrene (M₂) were carried out using AIBN as the initiator in toluene at 60°C. The number-average molecular weights (M _ns) were extremely low for poly(2-phenylethynylstyrene) (2a) and poly[(phenylethynyl)styrene-co-styrene] (3a), and increased in the order of 2a, 3a << 2b, 3b < 2c, 3c. Monomer reactivity ratios were determined as r ₁= 1.80 and r ₂= 0.51 for 1a, r ₁= 1.72 and r ₂= 0.53 for 1b, and r ₁= 3.17 and r ₂= 0.24 for 1c. Polymers 2a–c and 3a–c underwent an exothermic reaction at elevated temperature to form organic solvent-insoluble polymers. Although the decomposition of 2a was observed from 200°C, 2b and 2c exhibited a high heat-resistance property in both nitrogen and air atmospheres, in particular, 2b showed no significant weight loss below 450°C. Received: 28 January 1998/Accepted: 5 March 1998     

New epoxy/episulfide resin system for electronic applications. I. Curing mechanism and properties

A new epoxy/episulfide is investigated using a dicyandiamide (DICY) curing agent system. The resin exhibits better adhesion to copper, a lower thermal expansion coefficient, a lower heat of reaction, and slightly higher water absorption as compared with the standard epoxy system. The dielectric constant of the epoxy/episulfide system is almost the same as that of the standard epoxy system. The properties are due to the reaction mechanism change caused by the addition of episulfide, which is studied using a monofunctional model compound system; the amino groups in DICY initially react much more easily with the episulfide than with the epoxy ring. The S⁻ formed by this reaction reacts with the episulfide and the epoxy quickly. In the presence of copper, the episulfide and/or the S⁻ also react with copper, forming a durable bond between the copper and matrix resin that retains strength even after water boiling. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1359–1370, 2001