Surface enhanced Raman scattering (SERS) is a powerful tool for vibrational spectroscopy, providing orders of magnitude increase in chemical sensitivity compared to spontaneous Raman scattering. Yet it remains a challenge to synthesize robust, uniform SERS substrates quickly and easily. Lithographic approaches to produce substrates can achieve high, uniform sensitivity but are expensive and complex, thus difficult to scale. Facile solution-phase chemical approaches often result in unreliable SERS substrates due to heterogeneous arrangement of "hot spots" throughout the material. Here we demonstrate the synthesis and characterization of a homogeneous gold nanofoam (AuNF) substrate produced by a rapid, one-pot, four-ingredient synthetic approach. AuNFs are rapidly nucleated with macroscale porosity and then chemically roughened to produce nanoscale features that confer homogeneous and high signal enhancement (~10) across large areas, a comparable performance to lithographically produced substrates.

The rapid spread of Severe Acute Respiratory Syndrome-Coronavirus 2 (SARS-CoV-2) around the world has ravaged both global health and economy. This unprecedented situation has thus garnered attention globally. This further necessitated the deployment of an effective strategy for rapid and patient-compliant identification and isolation of patients tested positive for SARS-CoV-2. Following this, several companies and institutions across the globe are striving hard to develop real-time methods, like biosensors for the detection of various viral components including antibodies, antigens, ribonucleic acid (RNA), or the whole virus. This article attempts to review the various, mechanisms, advantages and limitations of the common biosensors currently being employed for detection. Additionally, it also summarizes recent advancements in various walks of fighting COVID-19, including its prevention, diagnosis and treatment.

Viral diseases are emerging as global threats. Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), that causes coronavirus disease (COVID-19), has severe global impacts. Safety, dosage, and potency of vaccines recently approved for emergency use against SARS-CoV-2 need further evaluation. There is still no effective treatment against COVID-19; therefore, safe, and effective vaccines or therapeutics against SARS-CoV-2 are urgently needed. Oil-in-water nanoemulsions (O/W NEs) are emerging as sophisticated, protective, and therapeutic platforms. Encapsulation capacity, which offers better drug pharmacokinetics, coupled with the tunable surfaces present NEs as promising tools for pharmaceutical applications. The challenges facing drug discovery, and the advancements of NEs in drug delivery demonstrate the potential of NEs against evolving diseases, like COVID-19. Here we summarize current COVID-19 knowledge and discuss the composition, stability, preparation, characterization, and biological fate of O/W NEs. We also provide insights into NE structural-functional properties that may contribute to therapeutic or preventative solutions against COVID-19.

Surfaces containing antiviral nanoparticles could play a crucial role in minimizing the virus spread further, specifically for COVID-19. Here in, we have developed a facile and durable antiviral and antimicrobial fabric containing photodeposited silver nanoparticles. Scanning and transmission electron microscopy, UV-VIS spectroscopy, and XPS are used to characterize the silver nanoparticles deposited cloth. It is evident that Ag/Ag redox couple is formed during fabrication, which acts as an active agent. Antiviral testing results show that silver nanoparticles deposited fabric exhibits 97% viral reduction specific to . Besides its excellent antiviral property, the modified fabric also offers antimicrobial efficiency when tested with the airborne human pathogenic bacteria and fungi . The direct photodeposition provides interaction leads to firmly grafted nanoparticles on fabric allow the modified fabric to sustain the laundry durability test. The straightforward strategy to prepare an efficient antimicrobial cloth can attract rapid large-scale industrial production.

Elevated expression of C-type like receptors (CLRs) by tumor cells and tumor-associated macrophages (TAMs) present a unique target for the delivery of anticancer agents. Stearoyl gemcitabine (GemC18)-incorporated, acid-sensitive micelles (G-AS-M) prepared with a stearoyl polyethylene glycol (PEG2000) hydrazone were surface-mannosylated in this study for potential targeted killing of tumor cells and TAMs. The surface mannosylated micelles (i.e. G-MAS-M) were significantly more cytotoxic than the G-AS-M micelles to macrophages and tumor cells that express CLRs. Surprisingly, the uptake of GemC18 in the mannosylated G-MAS-M micelles by the macrophages and tumor cells was lower than that of GemC18 in the G-AS-M micelles. The lack of correlation between the cytoxicity and cellular uptake of GemC18 in the micelles was likely caused by a reduction in the sensitivity of the hydrazone bond linking the PEG2000 to the mannosylated G-MAS-M micelles to hydrolysis, resulting in more stable micelles.

The affinity of the SARS-CoV-2 spike protein (S protein) to gold nano-particles was examined through spectral shifts of SPR (Surface Plasmon Resonance) band. Gold nano-colloidal particles are sensitive to the conformational change of the protein adsorbed over the particles' surface. As the pH value was gradually lowered from approximately neutral pH to an acidic pH ( pH 2), all mixtures of S protein with the gold colloids ≥30 nm in diameter exhibited a drastic red-shift of the average SPR band peak at one pH value more than that observed for bare gold colloids. The surface coverage fraction (Θ) of S protein over the nano-particle's surface was extracted and all showed relatively small coverage values ( Θ ~ 0.30). The SPR band peak shift was also examined as the pH values were hopped between pH ~ 3 and pH ~ 10 (pH hopping). As the pH values hopped, an alternation of the average SPR band peaks were observed. A significant amplitude of an alternation was especially observed for the mixture of S protein with gold ≥30 nm of gold size implying the reproduction of pH induced reversible protein folding. We hypothesize that the pH hopping scheme captured a reversible transition between folded or Down conformation (pH ≥ ~7) and unfolded or Up (pH ~ 3) conformation of RBD (receptor binding domain). The acidic condition may also dimerize the S protein through RBD. The Up conformation or dimerization of S protein are considered to be connected to the other gold nano particles forming gold nano-particle aggregates.

This manuscript describes the potentially significant role of interfacial tension in viral infection. Our hypothesis is based on evidence from drop coalescence hydrodynamics. A change in membrane tension can trigger fusion between the vesicle and cell such that genetic material, like viral RNA, can subsequently be transported to the cell interior. In other cases, RNA may reside near the cell membrane inside the cell, which could make their removal energetically unfavorable because of hydrodynamic interactions between membrane and RNA. Interfacial tension of the virus membrane can be modulated by temperature, among many other factors, of the mucosa layer. We discuss our hypothesis within the scope of recent SARS-CoV-2 studies where temperature-dependent membrane surface tension could be impacted through different atmospheric conditions, air conditioning systems, and the use of masks.

Propolis is a natural product originating from life activity of honeybees. It exhibits wide range of biological properties applicable in medicine, the food industry, and cosmetics. Chemically, propolis is a complex and variable mixture with more than 300 identified biologically active components. Propolis's many health-promoting effects are attributed to different biochemical mechanisms, mediated by often-concerted actions of some of its many constituents. Propolis is considered safe and biocompatible. Yet due to its intrinsic complexity, standardization of propolis preparations for medical use as well as prediction of e.g. pathogen-specific interactions becomes a non-trivial task. In this work we demonstrate a new physical mechanism of propolis action, largely independent of specific nuances of propolis chemistry, which may underlie some of its biological actions. We show that propolis-bearing surfaces generate an extensive exclusion zone (EZ) water layer. EZ is an interfacial region of water capable of excluding solutes ranging from ions to microorganisms. Propolis-generated EZ may constitute an effective barrier, physically disabling the approach of various pathogens to the propolis-functionalized surfaces. We suggest possible implications of this new mechanism for propolis-based prevention of respiratory infections.

Naturally-derived polysaccharides, such as alginate and chitosan, can be assembled to form nanocarriers for the delivery of therapeutic agents. Here we exploit the electrostatic complexation of alginate/chitosan in a water-in-oil (w/o) emulsion process to produce doxorubicin (DOX)-loaded nanoparticles (~80 nm) with exceptional spherical morphology and uniformity. This robust synthetic route utilizes an aqueous phase dispersed in a cyclohexane/dodecylamine organic phase and is capable of encapsulating DOX in the nanoparticle solution. The uptake and efficacy of this novel formulation was evaluated in a murine breast cancer cell line, 4T1, with comparable 72 h IC values of the nanoparticle solution (0.15 μg/mL) and free DOX (0.13 μg/mL). Overall, the favorable performance, physiochemical properties, and their facile production support these nanocarriers as promising platform for the delivery of aqueous soluble drugs.