Virucidal activity in vitro of mouthwashes against a feline coronavirus type II.

Transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can occur through saliva and aerosol droplets deriving from the upper aerodigestive tract during coughing, sneezing, talking, and even during oral inspection or dental procedures. The aim of this study was to assess in vitro virucidal activity of commercial and experimental mouthwashes against a feline coronavirus (FCoV) strain. Commercial and experimental (commercial-based products with addition of either sodium dodecyl sulfate (SDS) or thymus vulgaris essential oil (TEO) at different concentrations) mouthwashes were placed in contact with FCoV for different time intervals, that is, 30 s (T30), 60 s (T60), and 180 s (T180); subsequently, the virus was titrated on Crandell Reese Feline Kidney cells. An SDS-based commercial mouthwash reduced the viral load by 5 log10 tissue culture infectious dose (TCID)50 /50 µl at T30 while a cetylpyridinium (CPC)-based commercial mouthwash was able to reduce the viral titer of 4.75 log10 at T60. Furthermore, five experimental mouthwashes supplemented with SDS reduced the viral titer by 4.75-5 log10 according to a dose- (up to 4 mM) and time-dependent fashion.

Rational Design of Sustainable Liquid Microcapsules for Spontaneous Fragrance Encapsulation.

The high volatility, water-immiscibility, and light/oxygen-sensitivity of most aroma compounds represent a challenge to their incorporation in liquid consumer products. Current encapsulation methods entail the use of petroleum-based materials, initiators, and crosslinkers as well as mixing, heating, and purification steps. Hence, more efficient and eco-friendly approaches to encapsulation must be sought. Herein, we propose a simple method by making use of a pre-formed amphiphilic polymer and employing the Hansen Solubility Parameters approach to determine which fragrances could be encapsulated by spontaneous coacervation in water. The coacervates do not precipitate as solids but they remain suspended as colloidally stable liquid microcapsules, as demonstrated by fluorescence correlation spectroscopy. The effective encapsulation of fragrance is proven through confocal Raman spectroscopy, while the structure of the capsules is investigated by means of cryo FIB/SEM, confocal laser scanning microscopy, and small-angle X-ray scattering.

Selective single-molecule analytical detection of C-reactive protein in saliva with an organic transistor.

In the last decade, saliva has been suggested as non-invasive diagnostic fluid, suitable for clinical use alternatively to blood serum and plasma. However, the clinical applicability of saliva has been hampered so far by the inadequate sensitivity of current methods to detect the lower salivary concentrations of many biomarkers monitored in blood products. Herein, a label-free biosensor based on electrolyte-gated organic thin-film transistor (EGOTFT) has been developed for the detection at the physical limit of C-reactive protein (CRP) in human saliva. CRP is a key relevant biomarker for inflammatory processes and is routinely monitored for many clinical purposes. Herein, an electrolyte-gated thin-film transistor (EGOTFT) has been proposed as a transducer of the biorecognition event taking place at the gate electrode, functionalized with a self-assembled monolayer (SAM) of highly densely packed capturing anti-CRP proteins. Thanks to the SAM, the biosensing platform herein proposed is endowed with ultra-high sensitivity, along with an extremely high selectivity, assessed by measuring the dose curves of CRP interacting with a bovine serum albumin-functionalized gate. Moreover, the biosensing platform is compatible with low-cost fabrication techniques and applicable to the ultra-sensitive detection of a plethora of clinically relevant biomarkers. Therefore, the EGOTFT device herein proposed, being able to operate in physiologically relevant fluids such as saliva, will set the ground to a major revolution in biosensing applications for early clinical detection.

A Stereochemically Driven Supramolecular Polymerisation.

Anthracyclines self-assemble in water into dimers. In the presence of sufficiently high salt (NaCl) concentrations, solutions of the antibiotic doxorubicin, but not those of the closely related molecules daunomycin and epirubicin, turn into gels barely compatible with the presence of small oligomers. The use of spectroscopic, scattering, imaging and computational techniques, allowed light to be shed on the self-assembly process that triggered doxorubicin gelification. A complex picture emerged, with doxorubicin molecules assembled into long, highly chiral, supramolecular aggregates made of hundreds of units, showing redshifted fluorescence spectra, very short fluorescence lifetimes and small-angle X-ray scattering profiles compatible with long cylinders. The involvement of specific chemical groups and the need for a specific stereochemistry of the monomers in the formation of a hydrogen-bond network to stabilise the supramolecular aggregates was supported by molecular dynamics calculations. A salt-induced, temperature-dependent, cooperative nucleation-elongation supramolecular polymerisation of the doxorubicin molecules is deduced.

Ion beam sputtering deposition of silver nanoparticles and TiOx/ZnO nanocomposites for use in surface enhanced vibrational spectroscopy (SERS and SEIRAS).

Hybrids consisting of silver nanoparticles (in varying fractions) and of TiOx/ZnO were prepared via top-down ion beam sputtering (IBS) deposition on silicon substrates. The deposited nanomaterials were characterized by scanning electron microscopy and X-ray photoelectron spectroscopy. It is shown that such composites represent a viable substrate for use in both surface enhanced Raman spectroscopy (SERS) and surface enhanced infrared absorption spectroscopy (SEIRAS), as exemplarily shown for crystal violet as the model analyte. The C-H bending mode at about 1181 cm-1 and the C-N vibration at 1361 cm-1 observed in the SERS and SEIRAS spectra, respectively, have been used as analytical signal. The substrate consisting of TiOx NPs with 33% fraction of silver provides the strongest enhancement in SERS (up to 10,000-fold), while TiOx/AgNPs with thickness of 2 and 1 nm in ion beam sputtering, respectively, provides the best sensitivity in SEIRAS. The substrates also display photocatalytic activity as shown by the degradation of adsorbed crystal violet under ultraviolet irradiation. Graphical abstract Schematic of the preparation of hybrid substrates consisting of Ag and TiOx/ZnO nanoparticles via ion beam sputtering deposition. They were applied in both surface enhanced Raman and surface enhanced infrared absorption spectroscopies using crystal violet as model analyte, showing enhancements up to >10,000-fold in Raman.

Effect of ionic strength on intra-protein electron transfer reactions: The case study of charge recombination within the bacterial reaction center.

It is a common believe that intra-protein electron transfer (ET) involving reactants and products that are overall electroneutral are not influenced by the ions of the surrounding solution. The results presented here show an electrostatic coupling between the ionic atmosphere surrounding a membrane protein (the reaction center (RC) from the photosynthetic bacterium Rhodobacter sphaeroides) and two very different intra-protein ET processes taking place within it. Specifically we have studied the effect of salt concentration on: i) the kinetics of the charge recombination between the reduced primary quinone acceptor QA(-) and the primary photoxidized donor P(+); ii) the thermodynamic equilibrium (QA(-)↔QB(-)) for the ET between QA(-) and the secondary quinone acceptor QB. A distinctive point of this investigation is that reactants and products are overall electroneutral. The protein electrostatics has been described adopting the lowest level of complexity sufficient to grasp the experimental phenomenology and the impact of salt on the relative free energy level of reactants and products has been evaluated according to suitable thermodynamic cycles. The ionic strength effect was found to be independent on the ion nature for P(+)QA(-) charge recombination where the leading electrostatic term was the dipole moment. In the case of the QA(-)↔QB(-) equilibrium, the relative stability of QA(-) and QB(-) was found to depend on the salt concentration in a fashion that is different for chaotropic and kosmotropic ions. In such a case both dipole moment and quadrupole moments of the RC must be considered.

Solvent-gated thin-film-transistors.

Electrical double layer (EDL) thin film transistors (TFTs) are an interesting class of transistors that use an electrolyte as the gating medium. Recently it has been demonstrated that pure organic solvents can also be used as gating media for TFTs without the addition of exogenous electrolytes. Here we present a systematic study of the performances of TFTs based on two different semiconductors (P3HT and ZnO) gated through nine different solvents either pure or loaded with NaCl. The nature of the solvent impacts the transfer characteristics of the TFT through a change in the gating capacitance while the threshold voltage remains unaffected. Depending on the polarity of solvents, addition of NaCl gives rise to different responses. TFTs gated through highly polar solvents are unaffected by the salt concentration while for low polarity solvents the output current increases with salt up to a plateau. Furthermore, when the semiconductor surface is covered with a high capacitance thin dielectric layer, the TFT output current becomes dependent on the NaCl concentration also for high polarity solvents. This phenomenology was rationalized considering the different contributions of Helmholtz and Guy-Chapman EDLs to the capacitance and the dielectric saturation that decreases the solvent dielectric constant within the Helmholtz EDL.

Label-free C-reactive protein electronic detection with an electrolyte-gated organic field-effect transistor-based immunosensor.

In this contribution, we propose a label-free immunosensor, based on a novel type of electrolyte-gated field-effect transistor (EGOFET), for ultrasensitive detection of the C-reactive protein (CRP). The recognition layer of the biosensor is fabricated by physical adsorption of the anti-CRP monoclonal antibody onto a poly-3-hexyl thiophene (P3HT) organic semiconductor surface. A supplementary nonionic hydrophilic polymer is used as a blocking agent preventing nonspecific interactions and allowing a better orientation of the antibodies immobilized onto the P3HT surface. The whole biomolecule immobilization procedure does not require any pretreatment of the organic semiconductor surface, and the whole functionalization process is completed in less than 30 min. Surface plasmon resonance (SPR) measurements were performed to assess the amount of biomolecules physisorbed onto the P3HT and to evaluate the CRP binding proprieties of the deposited anti-CRP layer. A partial surface coverage of about 23 % of adsorbed antibody molecules was found to most efficiently sense the CRP. The electrical performance of the EGOFET immunosensor was comparable to that of a bare P3HT EGOFET device, and the obtained CRP calibration curve was linear over six orders of magnitude (from 4 pM to 2 µM). The relative standard deviation of the individual calibration points, measured on immunosensors fabricated on different chips, ranged between 1 and 14 %, and a detection limit of 2 pM (220 ng/L) was established. The novel electronic immunosensor is compatible with low-cost fabrication procedures and was successfully employed for the detection of the CRP biomarker in the clinically relevant matrix serum. Graphical abstract Schematic of the EGOFET immunosensor for CRP detection. The anti-CRP monoclonal antibody layer is physisorbed on the P3HT organic semiconductor and the CRP is directly measured by a label-free electronic EGOFET transducer.

General Approach to the Immobilization of Glycoenzyme Chains Inside Calcium Alginate Beads for Bioassay.

A general method to obtain the efficient entrapment of mixtures of glycoenzymes in calcium alginate hydrogel is proposed in this paper. As a proof of principle, three glycoenzymes acting in series (trehalase, glucose oxidase, and horseradish peroxidase) have been coimmobilized in calcium alginate beads. The release of the enzymes from the hydrogel mesh (leakage) is avoided by exploiting the enzyme's aggregation induced by the concanavalin A. The aggregation process has been monitored by dynamic light scattering technique, while both enzyme encapsulation efficiency and leakage have been quantified spectrophotometrically. Obtained data show an encapsulation efficiency above 95% and a negligible leakage from the beads when enzyme aggregates are larger than 300 nm. Operational stability of "as prepared" beads has been largely improved by a coating of alternated shells of polycation poly(diallyldimethylammonium chloride) and of alginate. As a test for the effectiveness of the overall procedure, analytical bioassays exploiting the enzyme-containing beads have been developed for the optical determination of glucose and trehalose, and limit of detection values of 0.2 and of 40 µM, respectively, have been obtained.

Interfacial electronic effects in functional biolayers integrated into organic field-effect transistors.

Biosystems integration into an organic field-effect transistor (OFET) structure is achieved by spin coating phospholipid or protein layers between the gate dielectric and the organic semiconductor. An architecture directly interfacing supported biological layers to the OFET channel is proposed and, strikingly, both the electronic properties and the biointerlayer functionality are fully retained. The platform bench tests involved OFETs integrating phospholipids and bacteriorhodopsin exposed to 1-5% anesthetic doses that reveal drug-induced changes in the lipid membrane. This result challenges the current anesthetic action model relying on the so far provided evidence that doses much higher than clinically relevant ones (2.4%) do not alter lipid bilayers' structure significantly. Furthermore, a streptavidin embedding OFET shows label-free biotin electronic detection at 10 parts-per-trillion concentration level, reaching state-of-the-art fluorescent assay performances. These examples show how the proposed bioelectronic platform, besides resulting in extremely performing biosensors, can open insights into biologically relevant phenomena involving membrane weak interfacial modifications.

Printable Bioelectronics To Investigate Functional Biological Interfaces.

Thin-film transistors can be used as high-performance bioelectronic devices to accomplish tasks such as sensing or controlling the release of biological species as well as transducing the electrical activity of cells or even organs, such as the brain. Organic, graphene, or zinc oxide are used as convenient printable semiconducting layers and can lead to high-performance low-cost bioelectronic sensing devices that are potentially very useful for point-of-care applications. Among others, electrolyte-gated transistors are of interest as they can be operated as capacitance-modulated devices, because of the high capacitance of their charge double layers. Specifically, it is the capacitance of the biolayer, being lowest in a series of capacitors, which controls the output current of the device. Such an occurrence allows for extremely high sensitivity towards very weak interactions. All the aspects governing these processes are reviewed here.

Investigation on the influence of (Z)-3-(2-(3-chlorophenyl)hydrazono)-5,6-dihydroxyindolin-2-one (PT2) on ß-amyloid(1-40) aggregation and toxicity.

In Alzheimer's disease (AD), native Aß protein monomers aggregate through the formation of a variety of water-soluble, toxic oligomers, ultimately leading to insoluble fibrillar deposits. The inhibition of oligomers formation and/or their dissociation into non-toxic monomers, are considered an attractive strategy for the prevention and treatment of AD. A number of studies have demonstrated that small molecules, containing single or multiple (hetero)aromatic rings, can inhibit protein aggregation, being potentially effective in AD treatment. Starting from previously reported data on the antiamyloidogenic activity of a series of 3-hydrazonoindolinones, compound PT2 was selected to deeply investigate the inhibitory mechanism in the Aß aggregation cascade. We compared data from DLS, NMR, CD, TEM and ThT fluorescence measures to ascertain the interactions with amyloidogenic species formed in vitro during the aggregation process, and confirmed this feature with cell viability tests on HeLa cultured cells. PT2 was effective in disrupting toxic oligomers and mature amyloid fibrils, stabilizing Aß as non-toxic, ß-sheet arranged, ThT-insensitive protofilaments. It also strongly reduced cellular toxicity caused by Aß and showed good antioxidant properties in two radical scavenging tests. Taken together, these data confirmed that PT2 is a small molecule inhibitor of Aß oligomerization and toxicity, displaying also additional activity as antioxidant.

Organic field-effect transistor sensors: a tutorial review.

The functioning principles of electronic sensors based on organic semiconductor field-effect transistors (OFETs) are presented. The focus is on biological sensors but also chemical ones are reviewed to address general features. The field-induced electronic transport and the chemical and biological interactions for the sensing, each occurring at the relevant functional interface, are separately introduced. Once these key learning points have been acquired, the combined picture for the FET electronic sensing is proposed. The perspective use of such devices in point-of-care is introduced, after some basics on analytical biosensing systems are provided as well. This tutorial review includes also a necessary overview of the OFET sensing structures, but the focus will be on electronic rather than electrochemical detection. The differences among the structures are highlighted along with the implications on the performance level in terms of key analytical figures of merit such as: repeatability, sensitivity and selectivity.

Celecoxib-hydroxypropyl-ß-cyclodextrin inclusion complex in a chitosan/PEO-PPO-PEO block copolymer matrix: Structural effect and drug release.

HYPOTHESIS: Triblock copolymers of poly(ethylene oxide) and poly(propylene oxide)-based matrices, such as Poloxamer 407 (P407) or Pluronic® F127, are extensively utilized in drug delivery and permeation systems due to their FDA approval and listing in the US and European Pharmacopoeias. The study hypothesizes that incorporating 2-hydroxypropyl-ß-cyclodextrin (HP-ß-CD) and the celecoxib-HP-ß-CD inclusion complex into a 16 wt% P407 and chitosan blend in an aqueous acetic acid solution will affect the system's rheological and structural properties. EXPERIMENTS: Rheological, small-angle X-ray scattering (SAXS), and dynamic light scattering (DLS) experiments were conducted to assess the impact of acetic acid and chitosan on the 16 wt% P407 and chitosan blend. Additionally, in vitro drug release studies were performed to monitor the drug release profile over time. FINDINGS: The addition of HP-ß-CD was found to inhibit gel formation in the 16 wt% P407 and chitosan blend. However, the presence of the celecoxib-HP-ß-CD inclusion complex showed no significant structural effects compared to P407 blended with chitosan alone. Rheological and SAXS analyses demonstrated that acetic acid led to the formation of a lamellar phase due to the lower pH, facilitating injectability. The presence of chitosan in acetic acid resulted in the detection of a hexagonal phase, affecting the release of celecoxib.

Mechanism of surfactant interactions with feline coronavirus: A physical chemistry perspective.

HYPOTHESIS: Surfactants are inexpensive chemicals with promising applications in virus inactivation, particularly for enveloped viruses. Yet, the detailed mechanisms by which surfactants deactivate coronaviruses remain underexplored. This study delves into the virucidal mechanisms of various surfactants on Feline Coronavirus (FCoV) and their potential applications against more pathogenic coronaviruses. EXPERIMENTS: By integrating virucidal activity assays with fluorescence spectroscopy, dynamic light scattering and laser Doppler electrophoresis, alongside liposome permeability experiments, we have analyzed the effects of non-ionic and ionic surfactants on viral activity. FINDINGS: The non-ionic surfactant octaethylene glycol monodecyl ether (C10EO8) inactivates the virus by disrupting the lipid envelope, whereas ionic surfactants like Sodium Dodecyl Sulfate and Cetylpyridinium Chloride predominantly affect the spike proteins, with their impact on the viral membrane being hampered by kinetic and thermodynamic constraints. FCoV served as a safe model for studying virucidal activity, offering a faster alternative to traditional virucidal assays. The study demonstrates that physicochemical techniques can expedite the screening of virucidal compounds, contributing to the design of effective disinfectant formulations. Our results not only highlight the critical role of surfactant-virus interactions but also contribute to strategic advancements in public health measures for future pandemic containment and the ongoing challenge of antimicrobial resistance.

Part per trillion label-free electronic bioanalytical detection.

A Functional Bio-Interlayer Organic Field-Effect Transistor (FBI-OFET) sensor, embedding a streptavidin protein capturing layer, capable of performing label-free selective electronic detection of biotin at 3 part per trillion (mass fraction) or 15 pM, is proposed here. The response shows a logarithmic dependence spanning over 5 orders of magnitude of analyte concentration. The optimization of the FBI analytical performances is achieved by depositing the capturing layer through a controllable Layer-by-Layer (LbL) assembly, while an easy processable spin-coating deposition is proposed for potential low-cost production of equally highly performing sensors. Furthermore, a Langmuirian adsorption based model allows rationalizing the analyte binding process to the capturing layer. The FBI-OFET device is shown to operate also with an antibody interlayer as well as with an ad hoc designed microfluidic system. These occurrences, along with the proven extremely high sensitivity and selectivity, open to FBI-OFETs consideration as disposable electronic strip-tests for assays in biological fluids requiring very low detection limits.

Collinear double pulse laser ablation in water for the production of silver nanoparticles.

Experiments of collinear Double Pulse Laser Ablation in Liquid (DP-LAL) were carried out for studying the production mechanisms of nanoparticles (NPs) in water, which revealed the fundamental role of the cavitation bubble dynamics in the formation of aqueous colloidal dispersions. In this work, DP-LAL was used to generate silver nanoparticles (AgNPs) from a silver target submerged in water at atmospheric pressure and room temperature, by using the second harmonic (532 nm) of two Nd:YAG lasers. The second laser pulse was shot at different delay times (i.e. interpulse delay) during the bubble temporal evolution of the first laser induced bubble. Optical Emission Spectroscopy, Shadowgraph Images, Surface Plasmon Resonance absorption spectroscopy and Dynamic Light Scattering were carried out to study the behaviour of laser-induced plasma and cavitation bubbles during the laser ablation in liquid, to monitor the generation of AgNPs under different conditions, and for characterization of NPs. The results of DP-LAL were always compared with the corresponding ones obtained with Single Pulse Laser Ablation in Liquid (SP-LAL), so as to highlight the peculiarities of the two different techniques.

Analytical probing of membranotropic effects of antimicrobial copper nanoparticles on lipid vesicles as membrane models.

Copper nanoparticles (CuNPs) are antimicrobial agents that are increasingly being used in several real-life goods. However, concerns are arising about their potential toxicity and thus, appropriate legislation is being issued in various countries. In vitro exploration of the permeability and the distribution of nanoparticles in cell membranes should be explored as the first step towards the investigation of the toxicity mechanisms of metal nanoantimicrobials. In this work, phosphatidylcholine-based large unilamellar vesicles have been explored as mimics of cellular membranes to investigate the effect of ultra-small CuNPs on the physicochemical features of phospholipid membranes. 4 nm-sized CuNPs were synthesized by a wet-chemical route that involves glutathione as a stabilizer, with further characterization by UV-vis absorption spectroscopy, fluorescence spectroscopy, transmission electron microscopy, X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FTIR) spectroscopy. Two fluorescent membrane probes bearing naphthalene moieties (laurdan and prodan) were used to monitor the bilayer structure and dynamics, as well as to demonstrate the strong membranotropic effects of CuNPs. The fluorescence spectroscopic studies were supported by dynamic light scattering (DLS) measurements and the calcein leakage assay. Additionally, the degree of perturbation of the phospholipid bilayer by CuNPs was compared against that of Cu2+ ions, the latter resulting in negligible effects. The findings suggested that CuNPs are able to damage the phospholipid membranes, leading to their agglomeration or disruption.

Preparation of Laser-Ablated Ag Nanoparticle-MMT Clay-Based Beeswax Antibiofilm Coating.

Unlike other antimicrobial agents, Ag-based composites are stable and currently widely used as broad spectral additives, fighting microbial biofilms and other biological threats. The goal of the present study is to develop a green, multifunctional, and robust antibiofilm water-insoluble coating, inhibiting histamine-producing Lentilactobacillus parabuchneri biofilms. Herein, laser-ablated Ag NPs (L-Ag NPs) were incorporated into and onto a montmorillonite (MMT) surface layer with a simple wet chemical method, provided that the electrostatic interaction between L-Ag NPs and MMT clay led to the formation of L-Ag/MMT nanoantimicrobials (NAMs). The use of MMT support can facilitate handling Ag NPs in industrial applications. The Ag/MMT composite was characterized with transmission electron microscopy (TEM) and scanning electron microscopy (SEM), which confirmed the entrapment of L-Ag NPs into MMT clay. The surface chemical composition was assessed with X-ray photoelectron spectroscopy, proving that Ag NPs were in contact with and deposited onto the surface of MMT. The characteristic L-Ag/MMT band was investigated with UV-vis spectroscopy. Following that, the L-Ag/MMT composite was embedded into a biosafe water-insoluble beeswax agent with a spin coating technique. The antimicrobial ion release kinetic profile of the L-Ag/MMT/beeswax coating through an electrothermal atomic absorption spectroscopy (ETAAS) study supported the controlled release of Ag ions, reaching a plateau at 420 ± 80 nM, which is safe from the point of view of Ag toxicity. Microbial biofilm growth inhibition was assessed with real-time in situ Fourier transform infrared attenuated total reflection spectroscopy (FTIR-ATR) in a flow cell assembly over 32 h. The study was further supported by optical density (OD) measurements and SEM on bacteria incubated in the presence of the L-Ag/MMT/beeswax coating.

Quantification of specific anion binding to non-ionic Triton X-100 micelles.

Anion binding to nonionic micelles was quantified by self-diffusion. Four anions were probed by multinuclear PGSTE NMR measurements in a Triton X-100 micellar aqueous solution. The salt concentration used was sufficiently low to avoid any micellar growth affecting surface curvature. The micellar aggregates that provide a model surface are uncharged with hydrophilic headgroups so that electrostatic ion surface interactions play little or no role in prescribing specific anion binding. Anionic affinity to the micellar surface followed a Hofmeister series, (CH(3))(2)AsO(2)(-) ≫ CH(3)COO(-) > H(2)PO(4)(-) > F(-). The observed ion specificity is rationalized by calling into play the nonelectrostatic interactions occurring between the anions and the micellar surface.