Rapid, sensitive detection of intact SARS-CoV-2 using DNA nets and a smartphone-linked fluorimeter

We report a single-step, room-temperature, 5-10 minute SARS-CoV-2 saliva self-monitoring method that overcomes the limitations of existing approaches through the use of fluorophore-releasing Designer DNA Nanostructures (DDNs) that bind with the multivalent pattern of spike proteins on the exterior intact virions and an inexpensive smartphone-linked, pocket-size fluorimeter, called a "V-Pod” for its resemblance to an Apple AirPod™ headphone case. We characterize the V-Pod fluorimeter performance and the DDN-based assay to demonstrate a clinically relevant detection limit of 104 virus particles/mL for pseudo-typed WT SARS-CoV-2 and 105 virus particles/mL for real pathogenic variants, including Delta, Omicron, and D614g. © 2023 SPIE.

Current Advances in Nanomaterial-associated Micro and Nano-devices for SARS-CoV-2 Detection

COVID-19 spread rapidly around the world in 18 months, with various forms of variants caused by severe acute respiratory syndrome (SARS-CoV). This has put pressure on the world community and created an urgent need for understanding its early occurrence through rapid, simple, cheap, and yet highly accurate diagnosis. The most widely adopted method as of today is the real-time reverse-transcriptase polymerase chain reaction. This test has shown the potential for rapid testing, but unfortunately, the test is not rapid and, in some cases, displays false negatives or false positives. The nanomaterials play an important role in creating highly sensitive systems, and have been thought to significantly improve the performance of the SARSCoV- 2 protocols. Several biosensors based on micro-and nano-sensors for SARS-CoV-2 detection have been reported, and they employ multi-dimensional hybrids on sensing surfaces with devices having different sizes and geometries. Zero-to-three-dimension nanomaterial hybrids on sensing surfaces, including nanofilm hybrids for SARS-CoV-2 detection, were employed with unprecedented sensitivity and accuracy. Furthermore, the sensors were nanofluidic and mediated high-performance SARS-CoV-2 detection. This breakthrough has brought the possibility of making a biosystem on a chip (Bio-SoC) for rapid, cheap, and point-of-care detection. This review summarises various advancements in nanomaterial-associated nanodevices and metasurface devices for detecting SARS-CoV-2.

Structural Characteristic of Fullerene C 60 and its Sorptive Properties

The pandemic situation associated with the occurrence of COVID-19 has necessitated the initiation or renewal of research activities aimed at the possibility of using materials that will have very good post-accident properties. One of the materials that have been developed, tested and applied in the past has been materials based on the spherical fullerene C 60 molecule. A microstructure using REM and SEM and sorptive properties of fullerene C 60 for gases of toluene with the employment of a QCM detector has been studied. Obtained micrographs are discussed in relation to a possible spatial arrangement at the molecular level. The envisaged solution aims to develop a sensor that, due to its surface properties, would be useful for the detection of gas and liquid phases of chemical warfare agents and industrial chemicals. It is envisaged that the surface layer consisting of fullerene C 60 will be universally applicable, reusable and low cost and low maintenance. © 2022 Challenges to National Defence in Contemporary Geopolitical Situation. All rights reserved.

Rapid detection of intact SARS-CoV-2 using designer DNA Nets and a pocket-size smartphone-linked fluorimeter.

Rapid, sensitive, and inexpensive point-of-care diagnosis is vital to controlling highly infectious diseases, including COVID-19. Here, we report the design and characterization of a compact fluorimeter called a "Virus Pod" (V-Pod) that enables sensitive self-testing of SARS-CoV-2 viral load in saliva. The rechargeable battery-operated device reads the fluorescence generated by Designer DNA Nanostructures (DDN) when they specifically interact with intact SARS-CoV-2 virions. DDNs are net-shaped self-assembling nucleic acid constructs that provide an array of highly specific aptamer-fluorescent quencher duplexes located at precise positions that match the pattern of spike proteins. The room-temperature assay is performed by mixing the test sample with DNA Net sensor in a conventional PCR tube and placing the tube into the V-Pod. Fluorescent signals are generated when multivalent aptamer-spike binding releases fluorescent quenchers, resulting in rapid (5-min) generation of dose-dependent output. The V-Pod instrument performs laser excitation, fluorescence intensity quantitation, and secure transmission of data to an App via Bluetooth™. We show that the V-Pod and DNA Net assay achieves clinically relevant detection limits of 3.92 × 103 viral-genome-copies/mL for pseudo-typed wild-type SARS-CoV-2 and 1.84 × 104, 9.69 × 104, 6.99 × 104 viral-genome-copies/mL for pathogenic Delta, Omicron, and D614G variants, representing sensitivity similar to laboratory-based PCR. The pocket-sized instrument (∼$294), inexpensive reagent-cost/test ($1.26), single-step, rapid sample-to-answer, and quantitative output represent a capability that is compatible with the needs of frequent self-testing in a consumer-friendly format that can link with medical service systems such as healthcare providers, contact tracing, and infectious disease reporting.

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

Electrochemical Immunosensors Based on Zinc Oxide Nanorods for Detection of Antibodies Against SARS-CoV-2 Spike Protein in Convalescent and Vaccinated Individuals

Even after over 2 years of the COVID-19 pandemic, research on rapid, inexpensive, and accurate tests remains essential for controlling and avoiding the global spread of SARS-CoV-2 across the planet during a potential reappearance in future global waves or regional outbreaks. Assessment of serological responses for COVID-19 can be beneficial for population-level surveillance purposes, supporting the development of novel vaccines and evaluating the efficacy of different immunization programs. This can be especially relevant for broadly used inactivated whole virus vaccines, such as CoronaVac, which produced lower titers of neutralizing antibodies. and showed lower efficacy for specific groups such as the elderly and immunocompromised. We developed an impedimetric biosensor based on the immobilization of SARS-CoV-2 recombinant trimeric spike protein (S protein) on zinc oxide nanorod (ZnONR)-modified fluorine-doped tin oxide substrates for COVID-19 serology testing. Due to electrostatic interactions, the negatively charged S protein was immobilized via physical adsorption. The electrochemical response of the immunosensor was measured at each modification step and characterized by scanning electron microscopy and electrochemical techniques. We successfully evaluated the applicability of the modified ZnONR electrodes using serum samples from COVID-19 convalescent individuals, CoronaVac-vaccinated with or without positive results for SARS-CoV-2 infection, and pre-pandemic samples from healthy volunteers as controls. ELISA for IgG anti-SARS-CoV-2 spike protein was performed for comparison, and ELISA for IgG anti-RBDs of seasonal coronavirus (HCoVs) was used to test the specificity of immunosensor detection. No cross-reactivity with HCoVs was detected using the ZnONR immunosensor, and more interestingly, the sensor presented higher sensitivity when compared to negative ELISA results. The results demonstrate that the ZnONRs/spike-modified electrode displayed sensitive results for convalescents and vaccinated samples and shows excellent potential as a tool for the population's assessment and monitoring of seroconversion and seroprevalence.

Dual-mode visual detection strategies of viable pathogens for point-of-care testing

Here, we introduce a power-free foldable poly(methyl methacrylate) (PMMA) microdevice fully integrating DNA extraction, amplification, and visual detection, realized in novel dual modes – colorimetric and aggregate formation – using 4-Aminoantipyrine (4-AP) for monitoring pathogens. The microdevice contains two parts: reaction and detection zones. A sealing film was utilized to connect the two zones and make the device foldable. The FTA card was deposited in the reaction zone for DNA extraction, followed by loop-mediated isothermal amplification (LAMP) at 65 °C for 45 min. When the detection zone is folded toward the reaction zone, paper discs modified with 4-AP placed in the detection zone are delivered to the reaction zone. Specifically, in the presence of LAMP amplicons, 4-AP is oxidized into antipyrine red or generates aggregates by interacting with copper sulfate, forming copper hybrid nanostructure (Cu-hNs). In the absence of LAMP amplicons, 4-AP is not oxidized and maintains yellow color or fails to form aggregates. Furthermore, we introduced the ethidium homodimer-1 (EthD-1) to identify viable bacteria. EthD-1 penetrated the compromised membranes of nonviable cells and prevented further DNA amplification by intercalating with the DNA. In this way, only samples containing viable cells displayed color change or formed aggregates upon reaction with 4-AP. Using this method, SARS-CoV-2 RNA and Enterococcus faecium were identified by naked eye, with the limit of detection of 103 copies/μL and 102 CFU/mL, respectively, within 60 min. The introduced microdevice can be used for rapidly monitoring viable pathogens and controlling outbreaks of infectious disease in resource-limited settings. © 2022 Elsevier B.V.

Nanomaterials in diagnostics, imaging and delivery: Applications from COVID-19 to cancer.

Abstract: In the past two decades, the emergence of nanomaterials for biomedical applications has shown tremendous promise for changing the paradigm of all aspects of disease management. Nanomaterials are particularly attractive for being a modularly tunable system; with the ability to add functionality for early diagnostics, drug delivery, therapy, treatment and monitoring of patient response. In this review, a survey of the landscape of different classes of nanomaterials being developed for applications in diagnostics and imaging, as well as for the delivery of prophylactic vaccines and therapeutics such as small molecules and biologic drugs is undertaken; with a particular focus on COVID-19 diagnostics and vaccination. Work involving bio-templated nanomaterials for high-resolution imaging applications for early cancer detection, as well as for optimal cancer treatment efficacy, is discussed. The main challenges which need to be overcome from the standpoint of effective delivery and mitigating toxicity concerns are investigated. Subsequently, a section is included with resources for researchers and practitioners in nanomedicine, to help tailor their designs and formulations from a clinical perspective. Finally, three key areas for researchers to focus on are highlighted; to accelerate the development and clinical translation of these nanomaterials, thereby unleashing the true potential of nanomedicine in healthcare.

Detection of SARS-COV-2 by functionally imprinted micelles.

The near real-time detection of airborne particles-of-interest is needed for avoiding current/future threats. The incorporation of imprinted particles into a micelle-based electrochemical cell produced a signal when brought into contact with particle analytes (such as SARS-COV-2), previously imprinted onto the structure. Nanoamp scales of signals were generated from what may've been individual virus-micelle interactions. The system showed selectivity when tested against similar size and morphology particles. The technology was compatible with airborne aerosol sampling techniques. Overall, the application of imprinted micelle technology could provide near real-time detection methods to a host of possible analytes of interest in the field. Supplementary Information: The online version contains supplementary material available at 10.1557/s43579-022-00242-0.

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.

Dual-mode visual detection strategies of viable pathogens for point-of-care testing

Here, we introduce a power-free foldable poly(methyl methacrylate) (PMMA) microdevice fully integrating DNA extraction, amplification, and visual detection, realized in novel dual modes–colorimetric and aggregate formation–using 4-aminoantipyrine (4-AP) for the first time for monitoring pathogens. The microdevice contains two parts: reaction and detection zones. A sealing film was utilized to connect the two zones and make the device foldable. The FTA card was deposited in the reaction zone for DNA extraction, followed by loop-mediated isothermal amplification (LAMP) at 65 °C for 45 min. When the detection zone is folded toward the reaction zone, paper discs modified with 4-AP placed in the detection zone are delivered to the reaction zone. Specifically, in the presence of LAMP amplicons, 4-AP is oxidized into red antipyrine or generates aggregates by interacting with copper sulfate, forming copper hybrid nanostructure (Cu-hNs). In the absence of LAMP amplicons, 4-AP is not oxidized and maintains yellow color or fails to form aggregates. Furthermore, we introduced the ethidium homodimer-1 (EthD-1) to identify viable bacteria. EthD-1 penetrated the compromised membranes of nonviable cells and prevented further DNA amplification by intercalating with the DNA. In this way, only samples containing viable cells displayed color change or formed aggregates upon reaction with 4-AP. Using this method, SARS-CoV-2 RNA and Enterococcus faecium were identified by naked eye, with the limit of detection of 103 copies/μL and 102 CFU/mL, respectively, within 60 min. The introduced microdevice can be used for rapidly monitoring viable pathogens and controlling outbreaks of infectious disease in resource-limited settings.

One-click investigation of shape influence of silver nanostructures on SERS performance for sensitive detection of COVID-19.

Sensitive and accurate detection of SARS-CoV-2 methods is meaningful for preventing and controlling the novel coronavirus. The detection techniques supporting portable, onsite, in-time, and online data transfer are urgently needed. Here, we one-click investigated the shape influence of silver nanostructures on SERS performance and their applications in the sensitive detection of SARS-CoV-2. Such investigation is achieved by adjusting multiple parameters (concentration, potential, and time) on the integrated electrochemical array, thus various morphologies (e.g., bulk, dendritic, globular, and spiky) can be one-click synthesized. The SERS performance results indicated that dendritic nanostructures are superior to the other three with an order of magnitude signal enhancement. Such on-electrode dendritic silver substrate also represents high sensitivity (LOD = 7.42 × 10-14 M) and high reproducibility (RSD = 3.67%) toward the SARS-CoV-2 RNA sequence detection. Such approach provides great potentials for rapid diagnosis and prevention of diverse infectious diseases.

Nanostructure machining and its application in surface information

Surface information is of significance in daily life, such as news displaying and information communication. The conventional methods that generate the surface information are to use chemical inks or dyes, which cause environmental pollution problems. Motived by this, this study proposes the mechanical machining method, named as vibration-assisted ultraprecision machining process, to fabricate orderly nanostructures to generate the surface information. Experimental results showed that the surface information “Beat the Covid-19” in the form of a quick response code was successfully machined on the workpiece surface. The information also can be hidden by manipulating the facet spacing of the adjacent nanostructures. The information “LOVE”, as an example, was hidden on the workpiece surface. It only can be observed at a certain viewing angle. Besides, a replication material was employed to replicate the generated surface information. Finally, the three-dimensional topographies of these orderly nanostructures were characterized and analyzed. The proposed method for generating, hiding, and replicating surface information extends the application range of the vibration-assisted ultraprecision machining process to information science.

Hybrid Nanocomposites of Plasmonic Metal Nanostructures and 2D Nanomaterials for Improved Colorimetric Detection

Plasmonic phenomena and materials have been extensively investigated for a long time and gained popularity in the last few years, finding in the design of the biosensors platforms promising applications offering devices with excellent performances. Hybrid systems composed of graphene, or other 2D materials, and plasmonic metal nanostructures present extraordinary optical properties originated from the synergic connection between plasmonic optical effects and the unusual physicochemical properties of 2D materials, thus improving their application in a broad range of fields. In this work, firstly, an overview of the structures and properties of 2D nanomaterials will be provided along with the physics of surface plasmon resonance and localized surface plasmon resonance. In the second part of the work, some examples of colorimetric biosensors exploiting the outstanding properties of hybrids nanocomposites will be presented. Finally, concluding perspectives on the actual status, challenges, and future directions in plasmonic sensing biosensing will be provided. Special emphasis will be given to how this technology can be used to support digitalization and virtualization in pandemic handling.

Chemotherapeutic effects of Apigenin in breast cancer: Preclinical evidence and molecular mechanisms; enhanced bioavailability by nanoparticles.

This review highlights using nanotechnology in increasing the bioavailability of AP (Apigenin) to enhance its therapeutic efficacy in breast cancer treatment. Breast cancer is one of the most leading causes of cancer death in women both in developed and developing countries. According to several epidemiological and clinical trial studies that indicate progestin-stimulated breast cancer in post-menopausal women; it is necessary to determine compounds to suppress or attenuate the tumor-promoting effects of progestins in breast cells. For this purpose, using the natural anti-progestins, including AP compared with the chemical ones could be significantly effective due to the lack of toxicities and contradiction effects. However, AP is categorized as a Class II drug of Biopharmaceutical Classification System with low solubility in water which limited its therapeutic effects. Therefore, nanotechnology due to the presentation of remarkable properties has overcome this limitation through enhanced the solubility and bioavailability of AP. In this regard, various nanocarriers such as nanocrystals, micelles, liposomes, PLGA, etc., have highlighted the significantly increased bioavailability and therapeutic efficacy of AP. Therefore, we will focus on the anticancer effects of AP in breast cancers, including involved mechanisms, the chemistry of AP and its bioavailability, finally different nanostructure systems to enhance the bioavailability of AP.

Aerosol capture and coronavirus spike protein deactivation by enzyme functionalized antiviral membranes

The airborne nature of coronavirus transmission makes it critical to develop new barrier technologies that can simultaneously reduce aerosol and viral spread. Here, we report nanostructured membranes with tunable thickness and porosity for filtering coronavirus-sized aerosols, combined with antiviral enzyme functionalization that can denature spike glycoproteins of the SARS-CoV-2 virus in low-hydration environments. Thin, asymmetric membranes with subtilisin enzyme and methacrylic functionalization show more than 98.90% filtration efficiency for 100-nm unfunctionalized and protein-functionalized polystyrene latex aerosol particles. Unfunctionalized membranes provided a protection factor of 540 ± 380 for coronavirus-sized particle, above the Occupational Safety and Health Administration’s standard of 10 for N95 masks. SARS-CoV-2 spike glycoprotein on the surface of coronavirus-sized particles was denatured in 30 s by subtilisin enzyme-functionalized membranes with 0.02-0.2% water content on the membrane surface.The COVID-19 pandemic highlights the importance of materials that block airborne virus transmission. Here, a nanostructured membrane is shown to filter coronavirus-sized particles, while the membrane surface incorporates enzymes that denature the SARS-CoV-2 spike protein within 30 s.

Triple-Probe DNA Framework-Based Transistor for SARS-CoV-2 10-in-1 Pooled Testing.

Accurate and population-scale screening technology is crucial in the control and prevention of COVID-19, such as pooled testing with high overall testing efficiency. Nevertheless, pooled testing faces challenges in sensitivity and specificity due to diluted targets and increased contaminations. Here, we develop a graphene field-effect transistor sensor modified with triple-probe tetrahedral DNA framework (TDF) dimers for 10-in-1 pooled testing of SARS-CoV-2 RNA. The synergy effect of triple probes as well as the special nanostructure achieve a higher binding affinity, faster response, and better specificity. The detectable concentration reaches 0.025-0.05 copy µL-1 in unamplified samples, lower than that of the reverse transcript-polymerase chain reaction. Without a requirement of nucleic-acid amplification, the sensors identify all of the 14 positive cases in 30 nasopharyngeal swabs within an average diagnosis time of 74 s. Unamplified 10-in-1 pooled testing enabled by the triple-probe TDF dimer sensor has great potential in the screening of COVID-19 and other epidemic diseases.

Research of Electromagnetic Field Enhancement of Surface Plasmon Resonant Mode in Metal Nanosphere-Nanodisc Structure

Surface plasmon has a history of more than one hundred years since its birth and has been a brand new discipline-plasmonics. Localized surface plasmon in metal nanostructures can gain very strong near-surface electric field enhancement and has been applied to many types researches successfully. However, there is relatively less study of the interaction between localized surface plasmon and magnetic field in incident light. This paper calculates the near-surface electromagnetic field enhancement of metal nanosphere-nanodisc gap based on the previous achievement. This paper shows that under the excitation of the single tightly radially polarized optical beam, the metal nanodisc can produce localized surface plasmon breathing mode and electric dipole moment mode, which give rise to the longitudinal electric field enhancement at the nanodisc center. And then, because of the resonance interaction of the metal nanodisc and localized surface plasmon electric dipolar moment of the metal nanosphere, a gap mode of localized surface plasmon resonance with efficient longitudinal electric field enhancement can be produced. Through carrying out the numerical simulation, this paper demonstrates that the near-surface longitudinal electric field of metal nanostructure gap mode can obtain 250 times electrical field enhancement relative to the valid transverse electrical field that is used to excite the breathing mode, and the enhancement factor of near-surface magnetic field could be 170. In order to present more clearly the character of the spectrum and the near-surface electromagnetic field distribution of this new metal nanostructure, the near-surface electromagnetic field distribution and the resonant wavelengths of this new metal nanostructure are also studied. The calculation results show that the proposed metal nanosphere-nanodisc nanostructure owns an obvious advantage on the local near-surface electromagnetic field enhancement and a relatively large frequency spectrum. Due to the electromagnetic field enhancement advantage of the metal nanostructure proposed by this paper, the future is not without hope that the results here could be applied to more and more researches, especially biomedicine, and provide a bit of reference in order to fight for novel coronavirus. © 2022, Peking University Press. All right reserved.

Multimeric RNAs for efficient RNA-based therapeutics and vaccines.

There has been a growing interest in RNA therapeutics globally, and much progress has been made in this area, which has been further accelerated by the clinical applications of RNA-based vaccines against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Following these successful clinical trials, various technologies have been developed to improve the efficacy of RNA-based drugs. Multimerization of RNA therapeutics is one of the most attractive approaches to ensure high stability, high efficacy, and prolonged action of RNA-based drugs. In this review, we offer an overview of the representative approaches for generating repetitive functional RNAs by chemical conjugation, structural self-assembly, enzymatic elongation, and self-amplification. The therapeutic and vaccine applications of engineered multimeric RNAs in various diseases have also been summarized. By outlining the current status of multimeric RNAs, the potential of multimeric RNA as a promising treatment strategy is highlighted.