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.

Synthesis Strategy of Tetrapyrrolic Photosensitizers for Their Practical Application in Photodynamic Therapy

This review presents a wide range of tetrapyrrole photosensitizers used for photodynamic therapy (PDT), antimicrobial photodynamic therapy, photoinactivation of pathogens. Methods of synthesis and design of new photosensitizers with greater selectivity of accumulation in tumor tissue and increased photoinduced antitumor activity are considered. The issues of studying the properties of new photosensitizers, their photoactivity, the ability to generate singlet oxygen, and the possibility of using targeted photodynamic therapy in clinical practice are discussed. The review examines the work on PDT by national and foreign researchers.

Functional Nanomaterials Enhancing Electrochemical Biosensors as Smart Tools for Detecting Infectious Viral Diseases.

Electrochemical biosensors are known as analytical tools, guaranteeing rapid and on-site results in medical diagnostics, food safety, environmental protection, and life sciences research. Current research focuses on developing sensors for specific targets and addresses challenges to be solved before their commercialization. These challenges typically include the lowering of the limit of detection, the widening of the linear concentration range, the analysis of real samples in a real environment and the comparison with a standard validation method. Nowadays, functional nanomaterials are designed and applied in electrochemical biosensing to support all these challenges. This review will address the integration of functional nanomaterials in the development of electrochemical biosensors for the rapid diagnosis of viral infections, such as COVID-19, middle east respiratory syndrome (MERS), influenza, hepatitis, human immunodeficiency virus (HIV), and dengue, among others. The role and relevance of the nanomaterial, the type of biosensor, and the electrochemical technique adopted will be discussed. Finally, the critical issues in applying laboratory research to the analysis of real samples, future perspectives, and commercialization aspects of electrochemical biosensors for virus detection will be analyzed.

Rejuvenation and Restoration of Surface Water Quality Amid COVID-19 Lockdown: A Comprehensive Review in Indian Context

Rivers are our country's lifeline;however, we have done enough destruction to them which leads to deterioration in water quality. Fortunately, COVID-19 lockdown has brought new life to nature. This encouraged us to outline present review article which discusses pilot impacts of lockdown on six Indian rivers. Few rivers including Ganga showed major improvement at few sites in the assessed parameters such as pH, BOD, DO, FC, etc. The Ganga water at Haridwar and Rishikesh was investigated `fit for drinking' (Class A) while at Kanpur was found fit for `outdoor bathing' (Class B). These improvements can be attributed to strict restriction on human activities during lockdown as there were no or minimum industrial discharge, tourism activities, mass bathing and commercial events near rivers. However, after upliftment of lockdown, these activities will return to their previous state and most likely pollutants will eventually reappear in the water bodies. So, in this review we have reviewed government's existing water pollution control schemes, analysed their limitations and recommended several scopes for improvement. Further research directions in this area have also been highlighted. We believe that plans and actions described in the article, if implemented, will lead to fruitful outcomes in managing water resources.

Programmable Nanostructures Based on Framework-DNA for Applications in Biosensing.

DNA has been actively utilized as bricks to construct exquisite nanostructures due to their unparalleled programmability. Particularly, nanostructures based on framework DNA (F-DNA) with controllable size, tailorable functionality, and precise addressability hold excellent promise for molecular biology studies and versatile tools for biosensor applications. In this review, we provide an overview of the current development of F-DNA-enabled biosensors. Firstly, we summarize the design and working principle of F-DNA-based nanodevices. Then, recent advances in their use in different kinds of target sensing with effectiveness have been exhibited. Finally, we envision potential perspectives on the future opportunities and challenges of biosensing platforms.

Spatially Addressable Multiplex Biodetection by Calibrated Micro/Nanostructured Surfaces.

A challenge of any biosensing technology is the detection of very low concentrations of analytes. The fluorescence interference contrast (FLIC) technique improves the fluorescence-based sensitivity by selectively amplifying, or suppressing, the emission of a fluorophore-labeled biomolecule immobilized on a transparent layer placed on top of a mirror basal surface. The standing wave of the reflected emission light means that the height of the transparent layer operates as a surface-embedded optical filter for the fluorescence signal. FLIC extreme sensitivity to wavelength is also its main problem: small, e.g., 10 nm range, variations of the vertical position of the fluorophore can translate in unwanted suppression of the detection signal. Herein, we introduce the concept of quasi-circular lenticular microstructured domes operating as continuous-mode optical filters, generating fluorescent concentric rings, with diameters determined by the wavelengths of the fluorescence light, in turn modulated by FLIC. The critical component of the lenticular structures was the shallow sloping side wall, which allowed the simultaneous separation of fluorescent patterns for virtually any fluorophore wavelength. Purposefully designed microstructures with either stepwise or continuous-slope dome geometries were fabricated to modulate the intensity and the lateral position of a fluorescence signal. The simulation of FLIC effects induced by the lenticular microstructures was confirmed by the measurement of the fluorescence profile for three fluorescent dyes, as well as high-resolution fluorescence scanning using stimulated emission depletion (STED) microscopy. The high sensitivity of the spatially addressable FLIC technology was further validated on a diagnostically important target, i.e., the receptor-binding domain (RBD) of the SARS-Cov2 via the detection of RBD:anti-S1-antibody.

Hybrid Peptide–Agarose Hydrogels for 3D Immunoassays

Recent advances in biosensing analytical platforms have brought relevant outcomes for novel diagnostic and therapy-oriented applications. In this context, 3D droplet microarrays, where hydrogels are used as matrices to stably entrap biomolecules onto analytical surfaces, potentially provide relevant advantages over conventional 2D assays, such as increased loading capacity, lower nonspecific binding, and enhanced signal-to-noise ratio. Here, we describe a hybrid hydrogel composed of a self-assembling peptide and commercial agarose (AG) as a suitable matrix for 3D microarray bioassays. The hybrid hydrogel is printable and self-adhesive and allows analyte diffusion. As a showcase example, we describe its application in a diagnostic immunoassay for the detection of SARS-CoV-2 infection. © 2023, The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.

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.

Worldwide fight against COVID-19 using nanotechnology, polymer science, and 3D printing technology.

One of the lethal illnesses that humanity has ever seen is COVID-19 irrefutably. The speed of virus spread is high and happens through polluted surfaces, respiratory droplets, and bodily fluids. It was found that without an efficient vaccine or specific treatment using personal protective equipment, preventing contamination of hands, and social distancing are the best ways to stay safe during the present pandemic. In this line, polymers, nanotechnology, and additive manufacturing, or 3D printing technology have been considered to probe, sense, and treat COVID-19. All aforementioned fields showed undeniable roles during the COVID-19 pandemic, which their contributions have been reviewed here. Finally, the effect of COVID-19 on the environment, alongside its positive and negative effects has been mentioned.

Vaccination Strategies Based on Bacterial Self-Assembling Proteins as Antigen Delivery Nanoscaffolds.

Vaccination has saved billions of human lives and has considerably reduced the economic burden associated with pandemic and endemic infectious diseases. Notwithstanding major advancements in recent decades, multitude diseases remain with no available effective vaccine. While subunit-based vaccines have shown great potential to address the safety concerns of live-attenuated vaccines, their limited immunogenicity remains a major drawback that still needs to be addressed for their use fighting infectious illnesses, autoimmune disorders, and/or cancer. Among the adjuvants and delivery systems for antigens, bacterial proteinaceous supramolecular structures have recently received considerable attention. The use of bacterial proteins with self-assembling properties to deliver antigens offers several advantages, including biocompatibility, stability, molecular specificity, symmetrical organization, and multivalency. Bacterial protein nanoassemblies closely simulate most invading pathogens, acting as an alarm signal for the immune system to mount an effective adaptive immune response. Their nanoscale architecture can be precisely controlled at the atomic level to produce a variety of nanostructures, allowing for infinite possibilities of organized antigen display. For the bottom-up design of the proteinaceous antigen delivery scaffolds, it is essential to understand how the structural and physicochemical properties of the nanoassemblies modulate the strength and polarization of the immune responses. The present review first describes the relationships between structure and the generated immune responses, before discussing potential and current clinical applications.

Modular Metal-Quinone Networks with Tunable Architecture and Functionality.

Nanostructured materials with tunable structures and functionality are of interest in diverse areas. Herein, metal ions are coordinated with quinones through metal-acetylacetone coordination bonds to generate a class of structurally tunable, universally adhesive, hydrophilic, and pH-degradable materials. A library of metal-quinone networks (MQNs) is produced from five model quinone ligands paired with nine metal ions, leading to the assembly of particles, tubes, capsules, and films. Importantly, MQNs show bidirectional pH-responsive disassembly in acidic and alkaline solutions, where the quinone ligands mediate the disassembly kinetics, enabling temporal and spatial control over the release of multiple components using multilayered MQNs. Leveraging this tunable release and the inherent medicinal properties of quinones, MQN prodrugs with a high drug loading (>89 wt %) are engineered using doxorubicin for anti-cancer therapy and shikonin for the inhibition of the main protease in the SARS-CoV-2 virus.

Nickel-Ion Activating Discarded COVID-19 Medical Surgical Masks for Forming Carbon-Nickel Composite Nanowires and Using as a High-Performance Lithium Battery Anode

With the prevalence of COVID-19, wearing medical surgical masks has become a requisite measure to protect against the invasion of the virus. Therefore, a huge amount of discarded medical surgical masks will be produced, which will become a potential hazard to pollute the environment and endanger the health of organisms without our awareness. Herein, a green and cost-effective way for the reasonable disposal of waste masks becomes necessary. In this work, we realized the transformation from waste medical surgical masks into high-quality carbon-nickel composite nanowires, which not only benefit the protection of the environment and ecosystem but also contribute to the realization of economic value. The obtained composite carbon-based materials demonstrate 70 S m-1 conductivity, 5.2 nm average pore diameters, 234 m2 g-1 surface areas, and proper graphitization degree. As an anode material for lithium-ion batteries, the prepared carbon composite materials demonstrate a specific capacity of 420 mA h g-1 after 800 cycles at a current density of 0.2 A g-1. It also displays good rate performance and decent cycling stability. Therefore, this study provides an approach to converting the discarded medical surgical masks into high-quality carbon nanowire anode materials to turn waste into treasure.

Smart Nanostructured Materials for SARS-CoV-2 and Variants Prevention, Biosensing and Vaccination.

The coronavirus disease 2019 (COVID-19) pandemic, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has raised great concerns about human health globally. At the current stage, prevention and vaccination are still the most efficient ways to slow down the pandemic and to treat SARS-CoV-2 in various aspects. In this review, we summarize current progress and research activities in developing smart nanostructured materials for COVID-19 prevention, sensing, and vaccination. A few established concepts to prevent the spreading of SARS-CoV-2 and the variants of concerns (VOCs) are firstly reviewed, which emphasizes the importance of smart nanostructures in cutting the virus spreading chains. In the second part, we focus our discussion on the development of stimuli-responsive nanostructures for high-performance biosensing and detection of SARS-CoV-2 and VOCs. The use of nanostructures in developing effective and reliable vaccines for SARS-CoV-2 and VOCs will be introduced in the following section. In the conclusion, we summarize the current research focus on smart nanostructured materials for SARS-CoV-2 treatment. Some existing challenges are also provided, which need continuous efforts in creating smart nanostructured materials for coronavirus biosensing, treatment, and vaccination.

Photodynamic viral inactivation assisted by photosensitizers

The deadly viruses, which are spreading worldwide at an alarming rate, are a major challenge for the life sci-ences. More efficient and cost-effective methods with fewer side effects can provide a good alternative to traditional drug-based methods. Currently, physical phenomena such as light in the form of photodynamic action are increasingly being used to inactivate viruses. Photodynamic inactivation (PDI) uses a photosensitizer (PS), light, and oxygen to generate reactive oxygen species (ROS) to inactivate microorganisms. This article reviews the use of existing PSs, as one of the essential anti-viral agents, and introduces new materials and strategies combined with PDI. Physiochemical properties of PSs and their role in interaction with virus components are discussed. Furthermore, the effectiveness of optical sensitizers with radiation methods to inactivate viruses is highlighted.

Hybrid Peptide-Agarose Hydrogels for 3D Immunoassays

Recent advances in biosensing analytical platforms have brought relevant outcomes for novel diagnostic and therapy-oriented applications. In this context, 3D droplet microarrays, where hydrogels are used as matrices to stably entrap biomolecules onto analytical surfaces, potentially provide relevant advantages over conventional 2D assays, such as increased loading capacity, lower nonspecific binding, and enhanced signal-to-noise ratio. Here, we describe a hybrid hydrogel composed of a self-assembling peptide and commercial agarose (AG) as a suitable matrix for 3D microarray bioassays. The hybrid hydrogel is printable and self-adhesive and allows analyte diffusion. As a showcase example, we describe its application in a diagnostic immunoassay for the detection of SARS-CoV-2 infection.

Determination of rSpike Protein by Specific Antibodies with Screen-Printed Carbon Electrode Modified by Electrodeposited Gold Nanostructures.

In this research, we assessed the applicability of electrochemical sensing techniques for detecting specific antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike proteins in the blood serum of patient samples following coronavirus disease 2019 (COVID-19). Herein, screen-printed carbon electrodes (SPCE) with electrodeposited gold nanostructures (AuNS) were modified with L-Cysteine for further covalent immobilization of recombinant SARS-CoV-2 spike proteins (rSpike). The affinity interactions of the rSpike protein with specific antibodies against this protein (anti-rSpike) were assessed using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) methods. It was revealed that the SPCE electroactive surface area increased from 1.49 ± 0.02 cm2 to 1.82 ± 0.01 cm2 when AuNS were electrodeposited, and the value of the heterogeneous electron transfer rate constant (k0) changed from 6.30 × 10-5 to 14.56 × 10-5. The performance of the developed electrochemical immunosensor was evaluated by calculating the limit of detection and limit of quantification, giving values of 0.27 nM and 0.81 nM for CV and 0.14 nM and 0.42 nM for DPV. Furthermore, a specificity test was performed with a solution of antibodies against bovine serum albumin as the control aliquot, which was used to assess nonspecific binding, and this evaluation revealed that the developed rSpike-based sensor exhibits low nonspecific binding towards anti-rSpike antibodies.

Co3O4/MoS2Nanostructures for NOxSensing

2D transition metal dichalcogenides have performed exceptionally as the active layer for chemiresistive gas sensors. Combining these materials with semiconductor oxides of tunable properties has proved to improve gas sensing and overall device performance due to the synergizing effect of the hybrid nanostructures. In this manuscript, we report the synthesis of a Co3O4/MoS2 nanostructure-based highly sensitive chemiresistive gas sensor selective toward NOx gases. An increase in air pollution has caused an equal increase in the concentrations of toxic NOx gases in the atmosphere. Exposure to these gases leads to grave health hazards such as pulmonary diseases and cardiovascular diseases. Furthermore, recent studies prove that NOx gases are also a contributor to COVID-19 fatality. We investigated the effect of the change in precursor concentration of cobalt nitrate (CoN2O6) and temperature on the gas sensor response. The precursor concentration was varied over an increasing range of molarities (1, 5, 10, and 25 mM), and it was observed that the gas sensor with a precursor concentration of 25 mM and an operating temperature of 200 °C exhibited the highest response of 145.7% toward NO2 gas (4.3 ppm) and then 105.37% toward NO (2.75 ppm). It was also noted that the device responded to NO2 gas of concentration as low as 300 ppb. This device was then subjected to an increasing range of temperatures (50, 100, 150, 200, 250, and 300 °C). A clear increase in the device performance was observed with an increase in temperature. It was found that the gas sensor was the most sensitive toward NO2 gas (4.3 ppm) and exhibited a response of 186.2% at 250 °C followed by NO (2.75 ppm) with a response of 141.6%. A stable and excellent response toward a low concentration of 50 ppb of NO2 was observed. Two activation energies (Ea) were calculated from the Arrhenius plot Ea1 (0.846 eV) between 150 and 200 °C and Ea2 (1.316 eV) between 200 and 250 °C, indicating multiple energy trapping. These results pave a way for a plausible application of Co3O4/MoS2 hybrid nanostructures for the detection and monitoring of NOx gases in the air. ©

Aptamers for Viral Detection and Inhibition.

Recent times have experienced more than ever the impact of viral infections in humans. Viral infections are known to cause diseases not only in humans but also in plants and animals. Here, we have compiled the literature review of aptamers selected and used for detection and inhibition of viral infections in all three categories: humans, animals, and plants. This review gives an in-depth introduction to aptamers, different types of aptamer selection (SELEX) methodologies, the benefits of using aptamers over commonly used antibody-based strategies, and the structural and functional mechanism of aptasensors for viral detection and therapy. The review is organized based on the different characterization and read-out tools used to detect virus-aptasensor interactions with a detailed index of existing virus-targeting aptamers. Along with addressing recent developments, we also discuss a way forward with aptamers for DNA nanotechnology-based detection and treatment of viral diseases. Overall, this review will serve as a comprehensive resource for aptamer-based strategies in viral diagnostics and treatment.

Control of antibiotic resistance and superinfections as a strategy to manage COVID-19 deaths

According to the World Health Organization (WHO), viral infections continue to emerge and pose severe problems to public health. In mid-December 2019, coronavirus (coronavirus disease 2019 [COVID-19]) infection begun scattering from China. Globally, there are growing worries about community infections, in light of pandemic characterization for the outbreak by the WHO. Some studies have found that 1 out of 7 COVID-19 patients have acquired secondary bacterial infection, and half of the patients who have died had such infections. The challenge of antibiotic resistance could become an enormous force contributing to the rise in illness and death associated with COVID-19, as lower respiratory tract infections are among the leading causes of mortality in critically ill ventilated-patients with COVID-19. The increasing prevalence of resistance to penicillin and other drugs among pneumococci has considerably complicated the treatment of acquired pneumonia. Resistance to other classes of antibiotics, traditionally used as alternatives in the treatment of pneumococcal infections, has also increased markedly in the recent years. Although the search for new antibiotics remains a top priority, the pipeline for new antibiotics is not encouraging, making it essential to search for other alternative solutions. Researching promising antimicrobial agents that are effective against COVID-19 as well as Streptococcus pneumoniae, which is a major cause of pneumonia, should be encouraged to reduce mortality related to COVID-19 infections. In this chapter, the relation between secondary infections and antibiotic resistance as contributors to high death rate among COVID-19 patients will be traced and highlighted. The possibility of using antimicrobial agents of plant origin, either independently or in combination with nanostructures, as preventive and/or treatment strategies for infections associated with COVID-19 will be reviewed. © 2022 Elsevier Inc.

Structures, properties, and challenges of emerging 2D materials in bioelectronics and biosensors

Bioelectronics are powerful tools for monitoring and stimulating biological and biochemical processes, with applications ranging from neural interface simulation to biosensing. The increasing demand for bioelectronics has greatly promoted the development of new nanomaterials as detection platforms. Recently, owing to their ultrathin structures and excellent physicochemical properties, emerging two‐dimensional (2D) materials have become one of the most researched areas in the fields of bioelectronics and biosensors. In this timely review, the physicochemical structures of the most representative emerging 2D materials and the design of their nanostructures for engineering high‐performance bioelectronic and biosensing devices are presented. We focus on the structural optimization of emerging 2D material‐based composites to achieve better regulation for enhancing the performance of bioelectronics. Subsequently, the recent developments of emerging 2D materials in bioelectronics, such as neural interface simulation, biomolecular/biomarker detection, and skin sensors are discussed thoroughly. Finally, we provide conclusive views on the current challenges and future perspectives on utilizing emerging 2D materials and their composites for bioelectronics and biosensors. This review will offer important guidance in designing and applying emerging 2D materials in bioelectronics, thus further promoting their prospects in a wide biomedical field.