Multiplex and Ultrasensitive Detection of Severe Acute Respiratory Syndrome Coronavirus 2 and Influenza A/B Nucleocapsid Proteins Based on Nanometer-Sized Core-Shell Superparamagnetic Antifouling Probes

Infections caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), influenza A (Flu A), and influenza B (Flu B) show similar clinical symptoms, such as cough, fever, and dyspnea, but patients infected by these viruses should be treated differently. The rapid and accurate diagnosis of infections caused by SARS-CoV-2, Flu A or Flu B is critical during the influenza season. Herein, we synthesized core-shell magnetic particles (MNPs) with excellent antifouling properties and applied them in the MNP-based immunochromatographic test (MICT) for simultaneous detection of SARS-CoV-2, Flu A, and Flu B nucleocapsid(N) proteins in 20 min. Two kinds of carboxyl-modified MNPs, MNP@pMBAA and MNP@Si-SA, were prepared and evaluated as probes in the MICT. Among them, the MNP@pMBAA showed lower nonspecific adsorption of proteins and low background noise in the application in MICTs. Particularly, the MNP@pMBAA50 bead-based MICT strip exhibited the highest signal-to-noise ratio for SARS-CoV-2 N protein detection with a limit of detection (LOD) of 0.072 ng/mL. Moreover, the proposed MICT strip demonstrated a minimal cross-reactivity and a broad linear dynamic detection range under a magnetic assay reader in the simultaneous detection of SARS-CoV-2, Flu A, and Flu B N proteins with relative LOD values of 0.0086, 0.012, and 0.018 ng/mL, respectively. The results demonstrated that the synthesized MNPs showed great potential for use as MICT probes for sensitive and multiplex detection of biomarkers in the development of point-of-care testing systems. © 2023 American Chemical Society.

One-Step Synthesis of Self-Stratification Core-Shell Latex for Antimicrobial Coating.

Herein, we describe a one-step method for synthesizing cationic acrylate-based core-shell latex (CACS latex), which is used to prepare architectural coatings with excellent antimicrobial properties. Firstly, a polymerizable water-soluble quaternary ammonium salt (QAS-BN) was synthesized using 2-(Dimethylamine) ethyl methacrylate (DMAEMA) and benzyl bromide by the Hoffman alkylation reaction. Then QAS-BN, butyl acrylate (BA), methyl methacrylate (MMA), and vinyltriethoxysilane (VTES) as reactants and 2,2'-azobis(2-methylpropionamidine) dihydrochloride (AIBA) as a water-soluble initiator were used to synthesize the CACS latex. The effect of the QAS-BN dosage on the properties of the emulsion and latex film was systematically investigated. The TGA results showed that using QAS-BN reduced the latex film's initial degradation temperature but improved its thermal stability. In the transmission electron microscopy (TEM) photographs, the self-stratification of latex particles with a high dosage of QAS-BN was observed, forming a core-shell structure of latex particles. The DSC, TGA, XPS, SEM, and performance tests confirmed the core-shell structure of the latex particles. The relationship between the formation of the core-shell structure and the content of QAS-BN was proved. The formation of the core-shell structure was due to the preferential reaction of water-soluble monomers in the aqueous phase, which led to the aggregation of hydrophilic groups, resulting in the formation of soft-core and hard-shell latex particles. However, the water resistance of the films formed by CACS latex was greatly reduced. We introduced a p-chloromethyl styrene and n-hexane diamine (p-CMS/EDA) crosslinking system, effectively improving the water resistance in this study. Finally, the antimicrobial coating was prepared with a CACS emulsion of 7 wt.% QAS-BN and 2 wt.% p-CMS/EDA. The antibacterial activity rates of this antimicrobial coating against E. coli and S. aureus were 99.99%. The antiviral activity rates against H3N2, HCoV-229E, and EV71 were 99.4%, 99.2%, and 97.9%, respectively. This study provides a novel idea for the morphological design of latex particles. A new architectural coating with broad-spectrum antimicrobial properties was obtained, which has important public health and safety applications.

Cu2O based on core-shell nanostructure for enhancing the fire-resistance, antibacterial properties and mechanical properties of epoxy resin

The hazards of epoxy resin (EP) are not only reflected in the large amount of smoke and heat released during combustion, but also in the long survival time of bacterial on their surfaces at a time when COVID-19 are prevalent. Therefore, it is crucial to improve the antibacterial properties and fire-resistance of EP. Herein, this paper reports a multifunctional nanoparticle (Cu2O@KF) to overcome this issue. It is found that Cu2O@KF can confer great fire-resistance (LOI = 34.7% and pHRR reduced by 56.3%), antibacterial properties (over 99.99% antibacterial efficiency), and mechanical properties (hardness and Young's modulus increased by 80.0% and 24.0%, respectively) at a low loading level (7 wt%). These ideal characteristics are derived from the multi-synergistic properties among Cu2O and KF. © 2022

Coronavirus-like Core-Shell-Structured Co@C for Hydrogen Evolution via Hydrolysis of Sodium Borohydride.

Constructing a reliable and robust cobalt-based catalyst for hydrogen evolution via hydrolysis of sodium borohydride is appealing but challenging due to the deactivation caused by the metal leaching and re-oxidization of metallic cobalt. A unique core-shell-structured coronavirus-like Co@C microsphere was prepared via pyrolysis of Co-MOF. This special Co@C had a microporous carbon coating to retain the reduced state of cobalt and resist the metal leaching. Furthermore, several nano-bumps grown discretely on the surface afforded enriched active centers. Applied in the pyrolysis of NaBH4, the Co@C-650, carbonized at 650 °C, exhibited the best activity and reliable recyclability. This comparable performance is ascribed to the increased metallic active sites and robust stability.

Cu2O based on core-shell nanostructure for enhancing the fire-resistance, antibacterial properties and mechanical properties of epoxy resin

The hazards of epoxy resin (EP) are not only reflected in the large amount of smoke and heat released during combustion, but also in the long survival time of bacterial on their surfaces at a time when COVID-19 are prevalent. Therefore, it is crucial to improve the antibacterial properties and fire-resistance of EP. Herein, this paper reports a multifunctional nanoparticle (Cu2O@KF) to overcome this issue. It is found that Cu2O@KF can confer great fire-resistance (LOI = 34.7% and pHRR reduced by 56.3%), antibacterial properties (over 99.99% antibacterial efficiency), and mechanical properties (hardness and Young's modulus increased by 80.0% and 24.0%, respectively) at a low loading level (7wt.%). These ideal characteristics are derived from the multi-synergistic properties among Cu2O and KF.

Insight into core -shell microporous zinc silicate adsorbent to eliminate antibiotics in aquatic environment under the COVID-19 pandemic.

Under the new crown pneumonia (COVID-19) epidemic, the intensive use of therapeutic drugs has caused certain hidden danger to the safety of the water environment. Therefore, the core-shell microporous zinc silicate (SiO2@ZSO) was successfully prepared and used for the adsorption of chloroquine phosphate (CQ), tetracycline (TC) and ciprofloxacin (CIP) for eliminating the threat of COVID-19. The adsorption efficiencies of 20 mg L-1 of CQ, TC and CIP by SiO2@ZSO were all up to 60% after 5 min. The adsorption capacity of SiO2@ZSO for CQ, TC and CIP can reach 49.01 mg g-1, 56.06 mg g-1 and 104.77 mg g-1, respectively. The adsorption process is primarily physical adsorption, which is heterogeneous, spontaneous and preferential. Moreover, the effects of temperature, pH, salinity, and reusability on the adsorption of CQ, TC, and CIP on SiO2@ZSO were investigated. The adsorption mechanism mainly involves electrostatic attraction, partitioning and hydrogen bonding, which is insightful through the changes of the elements and functional groups before and after adsorption. This work provides a solution to the problems faced by the treatment of pharmaceuticals wastewater under the COVID-19 epidemic.

TiO2/core-shell structured carbon support materials derived from hydrothermal carbonization of waste masks biomass: a green photocatalyst

Surgical masks have become mandatory to protect against the COVID-19 epidemic. For this reason, the amount of waste masks has also reached severe dimensions. Turning these waste masks into functional materials (MC) in a green synthesis method is critical. In this study, carbon material from waste masks was synthesized by the hydrothermal carbonization method (HTC) and was used to increase the photocatalytic activity of TiO2. In addition, TiO2 nanoparticles were successfully synthesized by the solvothermal method. Thermo-gravimetric analysis (TGA), scanning-electron microscope(SEM), x-ray diffraction (XRD), Fourier transform- infrared spectroscopy (FT-IR), energy dispersive x-ray(EDX), transmission-electron microscopy (TEM), x-ray photoelectron spectroscopy (XPS), electrochemical-impedance spectroscopy (EIS) and Brunauer–Emmett–Teller (BET) analyzes were performed to illuminate the photocatalytic properties of the MC-TiO2 photocatalyst. In this sense, the functionality of the shell-core skeleton-based new generation carbon material was also investigated. The photocatalytic activity of the green type of photocatalyst was detected by comparing methylene blue (MB) and phenol photodegradation rates. In photocatalytic degradation experiments, both UV-A effect and visible light effect were examined. New type of photocatalyst an exhibited excellent photocatalytic effect. Superior photodegradation capacity may be referred as to the core-shell composition and functional groups of the effective carbon support material synthesized by the HTC method. In particular, the photocatalytic effect of the novel carbon support material is discussed in-depth with the proposed mechanism. With the present study, we aimed to bring a green perspective to the photocatalytic studies in the literature.

Elucidating the neuropathophysiology of COVID-19 using quantum dot biomimetics of SARS-CoV-2

Quantum dots were encapsulated in polymeric phospholipid micelles conjugated to multiple ligands of SARS-CoV-2 spike protein to form fluorescent biomimetic nanoparticles for SARS-CoV-2 (COVID-QDs). Phosphatidylethanolaminepolyethylene glycol (PE:PEG) was appended with bis(4-methylphenyl)sulfone to form PE:PEG:bis-sulfone and self-assembled into micelles around CdSe/CdS core/shell quantum dots via thin-film rehydration. The introduction of the bis-sulfone group the surface of the micelle-encapsulated quantum dots provides multiple sites for conjugation to his-tagged SARS-CoV-2 spike protein via a bisalkylation mechanism. Based on the eluted unconjugated fraction, we estimate that an average of seven spike proteins are conjugated per COVID-QD. We treated an in-vitro model system for the neurovascular unit (NVU) with these COVID-QD constructs to investigate the COVID-QDs, and by proxy SARS-CoV-2, may modulate the NVU leading to the COVID-19 associated neuropathophysiology. © 2022 SPIE

Graphite nanocrystals coated paper-based electrode for detection of SARS-Cov-2 gene using DNA-functionalized Au@carbon dot core-shell nanoparticles.

Currently, the development of biosensors is an urgent need due to the rapid spread of SARS-CoV-2 and the limitations of current standard methods for the diagnosis of COVID-19. Hence, many researchers have focused on the design of high-performance biosensors for measuring coronavirus genes. In this study, a voltammetric genosensor was developed for the determination of SARS-CoV-2 RdRP gene based on the format of cDNA probe/Au@CD core-shell NPs/graphite nanocrystals (GNCs)/paper electrode. For the first time, graphite nanocrystals were used in the electrochemical biosensor design. This genosensor was exposed to different concentrations of virus gene and then the hybridization between cDNA probe and RdRP gene was monitored by redox-active toluidine blue (TB). With increasing the RdRP concentration, the reduction peak current of TB enhanced in a linear range of 0.50 pM-12.00 nM according to the regression equation of I (µA) = 7.60 log CRdRP (pM) + 25.78. The repeatability with a RSD of 2.2% clearly exhibited that the response of modified electrode is stable because of the high adhesion of GNC layer on the paper substrate and the high stability of cDNA-Au@CD bioconjugates. The spike-and-recovery studies showed the acceptable recoveries for the sputum samples (>95%).

Eco-friendly chitosan@silver/plant fiber membranes for masks with thermal comfortability and self-sterilization.

The surgical masks have been essential consumables for public in the COVID-19 pandemic. However, long-time wearing masks will make wearers feel uncomfortable and massive discarded non-biodegradable masks lead to a heavy burden on our environment. In this paper, we adopt degradable chitosan@silver (CS@Ag) core-shell fibers and plant fibers to prepare an eco-friendly mask with excellent thermal comfort, self-sterilization, and antiviral effects. The thermal network of CS@Ag core-shell fibers highly improves the in-plane thermal conductivity of masks, which is 4.45 times higher than that of commercial masks. Because of the electrical conductivity of Ag, the fabricated mask can be electrically heated to warm the wearer in a cold environment and disinfect COVID-19 facilely at room temperature. Meanwhile, the in-situ reduced silver nanoparticles (AgNPs) endow the mask with superior antibacterial properties. Therefore, this mask shows a great potential to address the urgent need for a thermally comfortable, antibacterial, antiviral, and eco-friendly mask. Supplementary Information: The online version contains supplementary material available at 10.1007/s10570-022-04582-x.

Hydroxyapatite/TiO2 Nanomaterial with Defined Microstructural and Good Antimicrobial Properties.

Due to the growing number of people infected with the new coronavirus globally, which weakens immunity, there has been an increase in bacterial infections. Hence, knowledge about simple and low-cost synthesis methods of materials with good structural and antimicrobial properties is of great importance. A material obtained through the combination of a nanoscale hydroxyapatite material (with good biocompatibility) and titanium dioxide (with good degradation properties of organic molecules) can absorb and decompose bacteria. In this investigation, three different synthesis routes used to prepare hydroxyapatite/titanium dioxide nanomaterials are examined. The morphology and semiquantitative chemical composition are characterized by scanning electron microscopy with energy dispersive X-ray analysis (SEM-EDX). The obtained materials' phase and structural characterization are determined using the X-ray powder diffraction method (XRD). The crystallite sizes of the obtained materials are in the range of 8 nm to 15 nm. Based on XRD peak positions, the hexagonal hydroxyapatite phases are formed in all samples along with TiO2 anatase and rutile phases. According to SEM and TEM analyses, the morphology of the prepared samples differs depending on the synthesis route. The EDX analysis confirmed the presence of Ti, Ca, P, and O in the obtained materials. The IR spectroscopy verified the vibration bands characteristic for HAp and titanium. The investigated materials show excellent antimicrobial and photocatalytic properties.

Prospects of NIR fluorescent nanosensors for green detection of SARS-CoV-2.

The pandemic of the novel coronavirus disease 2019 (COVID-19) is continuously causing hazards for the world. Effective detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can relieve the impact, but various toxic chemicals are also released into the environment. Fluorescence sensors offer a facile analytical strategy. During fluorescence sensing, biological samples such as tissues and body fluids have autofluorescence, giving false-positive/negative results because of the interferences. Fluorescence near-infrared (NIR) nanosensors can be designed from low-toxic materials with insignificant background signals. Although this research is still in its infancy, further developments in this field have the potential for sustainable detection of SARS-CoV-2. Herein, we summarize the reported NIR fluorescent nanosensors with the potential to detect SARS-CoV-2. The green synthesis of NIR fluorescent nanomaterials, environmentally compatible sensing strategies, and possible methods to reduce the testing frequencies are discussed. Further optimization strategies for developing NIR fluorescent nanosensors to facilitate greener diagnostics of SARS-CoV-2 for pandemic control are proposed.

Plastic Antibodies Mimicking the ACE2 Receptor for Selective Binding of SARS-CoV-2 Spike (Adv. Mater. Interfaces 5/2022)

Plastic Antibodies for Selective Binding of SARS-CoV-2 Spike In article number 2101925, Alex D. Batista, Beatriz Fresco-Cala, and co-workers design and synthesize the very first silane-based silica core/shell molecularly imprinted polymers using an epitope peptide from SARS-CoV-2 spike protein as a template, which can act as a synthetic angiotensin-converting enzyme 2 receptor (ACE2) and bind to SARS-CoV-2. The interactions between the epitope template and the organosilane monomers are predicted via molecular docking simulations.

Comprehensive Characterization of PVDF Nanofibers at Macro- and Nanolevel.

This study is focused on the characterization and investigation of polyvinylidene fluoride (PVDF) nanofibers from the point of view of macro- and nanometer level. The fibers were produced using electrostatic spinning process in air. Two types of fibers were produced since the collector speed (300 rpm and 2000 rpm) differed as the only one processing parameter. Differences in fiber's properties were studied by scanning electron microscopy (SEM) with cross-sections observation utilizing focused ion beam (FIB). The phase composition was determined by Fourier-transform infrared spectroscopy (FTIR) and Raman spectroscopy. The crystallinity was determined by differential scanning calorimetry (DSC), and chemical analysis of fiber's surfaces and bonding states were studied using X-ray photoelectron spectroscopy (XPS). Other methods, such as atomic force microscopy (AFM) and piezoelectric force microscopy (PFM), were employed to describe morphology and piezoelectric response of single fiber, respectively. Moreover, the wetting behavior (hydrophobicity or hydrophilicity) was also studied. It was found that collector speed significantly affects fibers alignment and wettability (directionally ordered fibers produced at 2000 rpm almost super-hydrophobic in comparison with disordered fibers spun at 300 rpm with hydrophilic behavior) as properties at macrolevel. However, it was confirmed that these differences at the macrolevel are closely connected and originate from nanolevel attributes. The study of single individual fibers revealed some protrusions on the fiber's surface, and fibers spun at 300 rpm had a core-shell design, while fibers spun at 2000 rpm were hollow.

Plastic Antibodies Mimicking the ACE2 Receptor for Selective Binding of SARS-CoV-2 Spike.

Molecular imprinting has proven to be a versatile and simple strategy to obtain selective materials also termed "plastic antibodies" for a wide variety of species, i.e., from ions to macromolecules and viruses. However, to the best of the authors' knowledge, the development of epitope-imprinted polymers for selective binding of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is not reported to date. An epitope from the SARS-CoV-2 spike protein comprising 17 amino acids is used as a template during the imprinting process. The interactions between the epitope template and organosilane monomers used for the polymer synthesis are predicted via molecular docking simulations. The molecularly imprinted polymer presents a 1.8-fold higher selectivity against the target epitope compared to non-imprinted control polymers. Rebinding studies with pseudoviruses containing SARS-CoV-2 spike protein demonstrate the superior selectivity of the molecularly imprinted matrices, which mimic the interactions of angiotensin-converting enzyme 2 receptors from human cells. The obtained results highlight the potential of SARS-CoV-2 molecularly imprinted polymers for a variety of applications including chem/biosensing and antiviral delivery.

New Acaciin-Loaded Self-Assembled Nanofibers as MPro Inhibitors Against BCV as a Surrogate Model for SARS-CoV-2.

BACKGROUND: SARS-COVID-2 has recently been one of the most life-threatening problems which urgently needs new therapeutic antiviral agents, especially those of herbal origin. PURPOSE: The study aimed to load acaciin (ACA) into the new self-assembled nanofibers (NFs) followed by investigating their possible antiviral effect against bovine coronavirus (BCV) as a surrogate model for SARS-COV-2. METHODS: ACA was identified using 1H-NMR and DEPT-Q 13C-NMR spectroscopy, the molecular docking study was performed using Autodock 4 and a modification of the traditional solvent injection method was applied for the synthesis of the biodegradable NFs. Different characterization techniques were used to inspect the formation of the NFs, which is followed by antiviral investigation against BCV as well as MTT assay using MDBK cells. RESULTS: Core/shell NFs, ranging between 80-330 nm with tiny thorn-like branches, were formed which attained an enhanced encapsulation efficiency (97.5 ± 0.53%, P<0.05) and a dual controlled release (a burst release of 65% at 1 h and a sustained release up to >24 h). The antiviral investigation of the formed NFs revealed a significant inhibition of 98.88 ± 0.16% (P<0.05) with IC50 of 12.6 µM against BCV cells. CONCLUSION: The results introduced a new, time/cost-saving strategy for the synthesis of biodegradable NFs without the need for electric current or hazardous cross-linking agents. Moreover, it provided an innovative avenue for the discovery of drugs of herbal origin for the fight against SARS-CoV-2 infection.