Electrical Detection Assay Based on Programmable Nucleic Acid Probe for Efficient Single-Nucleotide Polymorphism Identification.

The large-scale pandemic and fast evolution of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants have triggered an urgent need for an efficient and sensitive on-site nucleic acid testing method with single-nucleotide polymorphism (SNP) identification capability. Here, we report a multiplexed electrical detection assay based on a paperclip-shaped nucleic acid probe (PNprobe) functionalized field-effect transistor (FET) biosensor for highly sensitive and specific detection and discrimination of SARS-CoV-2 variants. The three-stem structure of the PNprobe significantly amplifies the thermodynamic stability difference between variant RNAs that differ in a single-nucleotide mutation. With the assistance of combinatorial FET detection channels, the assay realizes simultaneously the detection and identification of key mutations of seven SARS-CoV-2 variants, including nucleotide substitutions and deletions at single-nucleotide resolution within 15 min. For 70 simulated throat swab samples, the multiplexed electrical detection assay shows an identification accuracy of 97.1% for the discrimination of SARS-CoV-2 variants. Our designed multiplexed electrical detection assay with SNP identification capability provides an efficient tool to achieve scalable pandemic screening.

Robust Covalent Aptamer Strategy Enables Sensitive Detection and Enhanced Inhibition of SARS-CoV-2 Proteins.

Aptamer-based detection and therapy have made substantial progress with cost control and easy modification. However, the conformation lability of an aptamer typically causes the dissociation of aptamer-target complexes during harsh washes and other environmental stresses, resulting in only moderate detection sensitivity and a decreasing therapeutic effect. Herein, we report a robust covalent aptamer strategy to sensitively detect nucleocapsid protein and potently neutralize spike protein receptor binding domain (RBD), two of the most important proteins of SARS-CoV-2, after testing different cross-link electrophilic groups via integrating the specificity and efficiency. Covalent aptamers can specifically convert aptamer-protein complexes from the dynamic equilibrium state to stable and irreversible covalent complexes even in harsh environments. Covalent aptamer-based ELISA detection of nucleocapsid protein can surpass the gold standard, antibody-based sandwich ELISA. Further, covalent aptamer performs enhanced functional inhibition to RBD protein even in a blood vessel-mimicking flowing circulation system. The robust covalent aptamer-based strategy is expected to inspire more applications in accurate molecular modification, disease biomarker discovery, and other theranostic fields.

Cover Feature: Structure‐ and Interaction‐Based Design of Anti‐SARS‐CoV‐2 Aptamers (Chem. Eur. J. 12/2022)

Digital drug design reveals DNA aptamers binding SARS‐CoV‐2: A hybrid in silico et vitro approach, structure and interaction‐based drug design, has been developed to create highly specific DNA aptamers for the receptor‐binding domain of the SARS‐CoV‐2 spike protein. The structure and binding affinity of the aptamers were validated by small‐angle X‐ray scattering, flow cytometry, and fluorescence polarization. This approach offers a blueprint for the straightforward design of targeting molecules for new pathogens and emerging variants. More information can be found in the Research Article by Y. Alexeev, M. V. Berezovski, A. S. Kichkailo, et al. (DOI: 10.1002/chem.202104481).

Structure- and Interaction-Based Design of Anti-SARS-CoV-2 Aptamers.

Aptamer selection against novel infections is a complicated and time-consuming approach. Synergy can be achieved by using computational methods together with experimental procedures. This study aims to develop a reliable methodology for a rational aptamer in silico et vitro design. The new approach combines multiple steps: (1) Molecular design, based on screening in a DNA aptamer library and directed mutagenesis to fit the protein tertiary structure; (2) 3D molecular modeling of the target; (3) Molecular docking of an aptamer with the protein; (4) Molecular dynamics (MD) simulations of the complexes; (5) Quantum-mechanical (QM) evaluation of the interactions between aptamer and target with further analysis; (6) Experimental verification at each cycle for structure and binding affinity by using small-angle X-ray scattering, cytometry, and fluorescence polarization. By using a new iterative design procedure, structure- and interaction-based drug design (SIBDD), a highly specific aptamer to the receptor-binding domain of the SARS-CoV-2 spike protein, was developed and validated. The SIBDD approach enhances speed of the high-affinity aptamers development from scratch, using a target protein structure. The method could be used to improve existing aptamers for stronger binding. This approach brings to an advanced level the development of novel affinity probes, functional nucleic acids. It offers a blueprint for the straightforward design of targeting molecules for new pathogen agents and emerging variants.

Spherical Neutralizing Aptamer Inhibits SARS-CoV-2 Infection and Suppresses Mutational Escape.

New neutralizing agents against SARS-CoV-2 and associated mutant strains are urgently needed for the treatment and prophylaxis of COVID-19. Herein, we develop a spherical cocktail neutralizing aptamer-gold nanoparticle (SNAP) to block the interaction between the receptor-binding domain (RBD) of SARS-CoV-2 and host ACE2. With the multivalent aptamer assembly as well as the steric hindrance effect of the gold scaffold, SNAP exhibits exceptional binding affinity against the RBD with a dissociation constant of 3.90 pM and potent neutralization against authentic SARS-CoV-2 with a half-maximal inhibitory concentration of 142.80 fM, about 2 or 3 orders of magnitude lower than that of the reported neutralizing aptamers and antibodies. More importantly, the synergetic blocking strategy of multivalent multisite binding and steric hindrance ensures broad neutralizing activity of SNAP, almost completely blocking the infection of three mutant pseudoviruses. Overall, the SNAP strategy provides a new direction for the development of antivirus agents against SARS-CoV-2 and other emerging coronaviruses.

DeepR2cov: deep representation learning on heterogeneous drug networks to discover anti-inflammatory agents for COVID-19.

Recent studies have demonstrated that the excessive inflammatory response is an important factor of death in coronavirus disease 2019 (COVID-19) patients. In this study, we propose a deep representation on heterogeneous drug networks, termed DeepR2cov, to discover potential agents for treating the excessive inflammatory response in COVID-19 patients. This work explores the multi-hub characteristic of a heterogeneous drug network integrating eight unique networks. Inspired by the multi-hub characteristic, we design 3 billion special meta paths to train a deep representation model for learning low-dimensional vectors that integrate long-range structure dependency and complex semantic relation among network nodes. Based on the representation vectors and transcriptomics data, we predict 22 drugs that bind to tumor necrosis factor-α or interleukin-6, whose therapeutic associations with the inflammation storm in COVID-19 patients, and molecular binding model are further validated via data from PubMed publications, ongoing clinical trials and a docking program. In addition, the results on five biomedical applications suggest that DeepR2cov significantly outperforms five existing representation approaches. In summary, DeepR2cov is a powerful network representation approach and holds the potential to accelerate treatment of the inflammatory responses in COVID-19 patients. The source code and data can be downloaded from https://github.com/pengsl-lab/DeepR2cov.git.

Rapid One-Step Detection of Viral Particles Using an Aptamer-Based Thermophoretic Assay.

Rapid and sensitive identification of viral pathogens such as SARS-CoV-2 is a critical step to control the pandemic disease. Viral antigen detection can compete with gold-standard PCR-based nucleic acid diagnostics in terms of better reflection of viral infectivity and reduced risk of contamination from enzymatic amplification. Here, we report the development of a one-step thermophoretic assay using an aptamer and polyethylene glycol (PEG) for direct quantitative detection of viral particles. The assay relies on aptamer binding to the spike protein of SARS-CoV-2 and simultaneous accumulation of aptamer-bound viral particles in laser-induced gradients of temperature and PEG concentration. Using a pseudotyped lentivirus model, a limit of detection of ∼170 particles µL-1 (26 fM of the spike protein) is achieved in 15 min without the need of any pretreatment. As a proof of concept, the one-step thermophoretic assay is used to detect synthetic samples by spiking viral particles into oropharyngeal swabs with an accuracy of 100%. The simplicity, speed, and cost-effectiveness of this thermophoretic assay may expand the diagnostic tools for viral pathogens.

Rapid One-Pot Detection of SARS-CoV-2 Based on a Lateral Flow Assay in Clinical Samples.

Rapid tests for pathogen identification and spread assessment are critical for infectious disease control and prevention. The control of viral outbreaks requires a nucleic acid diagnostic test that is sensitive and simple and delivers fast and reliable results. Here, we report a one-pot direct reverse transcript loop-mediated isothermal amplification (RT-LAMP) assay of SARS-CoV-2 based on a lateral flow assay in clinical samples. The entire contiguous sample-to-answer workflow takes less than 40 min from a clinical swab sample to a diagnostic result without professional instruments and technicians. The assay achieved an accuracy of 100% in 12 synthetic and 12 clinical samples compared to the data from PCR-based assays. We anticipate that our method will provide a universal platform for rapid and point-of-care detection of emerging infectious diseases.

A materials-science perspective on tackling COVID-19.

The ongoing SARS-CoV-2 pandemic highlights the importance of materials science in providing tools and technologies for antiviral research and treatment development. In this Review, we discuss previous efforts in materials science in developing imaging systems and microfluidic devices for the in-depth and real-time investigation of viral structures and transmission, as well as material platforms for the detection of viruses and the delivery of antiviral drugs and vaccines. We highlight the contribution of materials science to the manufacturing of personal protective equipment and to the design of simple, accurate and low-cost virus-detection devices. We then investigate future possibilities of materials science in antiviral research and treatment development, examining the role of materials in antiviral-drug design, including the importance of synthetic material platforms for organoids and organs-on-a-chip, in drug delivery and vaccination, and for the production of medical equipment. Materials-science-based technologies not only contribute to the ongoing SARS-CoV-2 research efforts but can also provide platforms and tools for the understanding, protection, detection and treatment of future viral diseases.