Single-Nanoparticle-Based Digital SERS Sensing Platform for the Accurate Quantitative Detection of SARS-CoV-2

Revolutionizing Escherichia coli detection in real samples with digital SERS aptamer sensor technology

Aptamer sensors based on surface-enhanced Raman scattering (SERS) technology have demonstrated great potential in the ultrasensitive and rapid detection of Escherichia coli (E. coli). Herein, this paper presents a digital SERS aptamer sensor. This sensor integrates ordered nanoscale array synthesis technology and digital analysis technology, enabling highly sensitive and rapid bacterial quantification. The ordered monolayer gold nanosphere arrays (Au NS) can form uniform and dense "hot spots" on the silicon wafer due to their uniform spherical structures and narrow gaps. Moreover, digital SERS is adopted to further optimize the signal uniformity so as to achieve precise quantification. The sensor modules are combined together through base pairing. The aptamers labeled with Raman tags are detached from the complementary DNA due to the competition of the target substance, thus realizing the detection of E. coli. The digital SERS aptamer sensor has been verified to possess excellent selectivity and reproducibility. It has a wide dynamic linear detection range from 1.0 * 101 to 1.0 * 109 CFU/ml and a detection limit of 0.657 CFU/ml, maintaining excellent specificity even in the presence of mixed bacterial interference. The spiked recoveries in actual samples range from 98.80 % to 99.81 %. Leveraging different aptamers and digital analysis, the sensor holds promise for food safety and environmental monitoring applications.

Emerging trends of biomedical nanotechnology in nutrition, health monitoring and disease diagnosis

The transdisciplinary nature of nanotechnology has facilitated its application across various fields, especially in biological sciences. The primary aim of this review is to consolidate the many facets of nanomedicine, theranostics, and nanotechnology in food preservation into a unified framework and to underscore established research methodologies in the medical domain. Nanoparticles serve a crucial function in improving the bioavailability of orally delivered bioactive substances. This review demonstrated that nanoparticles can enhance the bioavailability of micronutrients, such as vitamin B12, vitamin A, folic acid, and iron. New advances in nanotechnology have made big differences in finding pathogens and killing them specifically, helping people to get better health through medication delivery and imaging, improving food packaging better so it lasts longer, and making foods healthier overall. Nanotechnology currently enhances the safety of delivering highly hazardous medicines through the use of nanozymes that exhibit antioxidant and antibacterial characteristics. Moreover, wearable devices can identify significant alterations in vital signs, medical problems, and infections occurring within the body. We anticipate that these technologies will provide physicians with enhanced direct access to crucial information about the causes of changes in vital signs or diseases, as they are directly connected to the source of the problem. This review paper thoroughly examines the latest developments in nanomaterials and nanozymes as antimicrobial agents in food science and nutrition, wound healing, illness diagnostics, imaging, and potential future uses. The paper presents a concise and structured report on nanotechnology, which will be beneficial to researchers and scientists for future research opportunities.

Digital SERS Nanostructured Platform for Amplification-free Single-Molecule DNA Detection and Pre-Symptomatic Diagnosis of Kiwifruit Soft Rot

We present a digital surface-enhanced Raman spectroscopy (SERS) platform enabling enzyme- and amplification-free single-molecule DNA detection through Poisson distribution-driven quantification and geometrically optimized plasmonic nanostructures. Utilizing high-throughput UV lithography, we fabricated large-area nanopillar arrays (1.5 × 1.5 cm) with tunable heights (500-1300 nm) and periodicities (4-10 μm), addressing key limitations in conventional SERS methods via three innovations: (1) dynamic hotspot generation: Target DNA induces plasmonic dimerization between functionalized gold nanoprobes and Au-capped nanopillars, creating spatially resolved SERS enhancement (1326 cm-1 DTNB signal), (2) digital counting algorithms: Compensate Raman intensity variations by quantifying activated pillars as discrete molecular events, and (3) geometric confinement: Spatial confinement effects enabling statistically robust single-molecule occupancy. This platform achieved 10 fM sensitivity for Diaporthe spp. DNA detection, outperforming PCR-electrophoresis (1 pM) by 2 orders of magnitude. Applied to presymptomatic kiwifruit diagnosis, the system identified pathogen DNA in asymptomatic samples prior to visual symptom development, validated by characteristic DTNB peaks (1326 cm-1) absent in negative controls. The modular design permits multiplexed detection through probe diversification, while the absence of enzymatic steps enables field-deployable operation. By integrating single-molecule statistics with plasmonic signal amplification, this work establishes a robust framework for precision molecular diagnostics, demonstrating transformative potential for agricultural pathogen surveillance and low-abundance biomarker analysis. The technology's batch-producible nanopillar architecture and digital quantification strategy overcome longstanding reproducibility challenges in SERS-based detection, positioning it as a versatile tool for next-generation biosensing applications.

Ultrasensitive SERS nanoprobe-based multiplexed digital sensing platform for the simultaneous quantification of Alzheimer's disease biomarkers

Alzheimer's disease (AD) is a severe neurodegenerative disease that requires early diagnosis to manage its progression. Although the simultaneous detection of multiple AD biomarkers is expected to facilitate early assessment of AD risk, the lack of multiplexed sensing platforms for accurately quantifying multiple AD biomarkers remains a challenge. Here, we present a multiplexed digital sensing platform based on bumpy core-shell (BCS) surface-enhanced Raman spectroscopy (SERS) nanoprobes for ultrasensitive, quantitative, and simultaneous detection of Aβ42 and Aβ40 as AD biomarkers, enabling the accurate determination of the Aβ42/Aβ40 ratio. We synthesized BCS SERS nanoprobes with distinct Raman reporters to generate unique, intense, and reproducible SERS signals, offering single-nanoparticle sensitivity and quantification capabilities. These nanoprobes were subsequently employed in SERS-based immunoassays combined with digital SERS analysis for multiplexed quantification. The proposed platform accurately and quantitatively detected Aβ42 and Aβ40 across a range of five orders of magnitude, with a limit of detection of 8.7× 10-17 g/mL (1.9 × 10-17 M) for Aβ42 and 1.0 × 10-15 g/mL (2.3 × 10-16 M) for Aβ40, surpassing the performance of conventional enzyme-linked immunosorbent assays. Based on the exclusive detection of Aβ42 and Aβ40 using distinct SERS nanoprobes, the proposed sensing platform can also accurately quantify Aβ42 and Aβ40 at clinically relevant levels in both cerebrospinal fluid and blood plasma. Therefore, this sensing platform can be used to accurately and reliably determine the Aβ42/Aβ40 ratio, thus serving as an effective tool for the early diagnosis of AD.

Opto-digital molecular analytics

In contrast to conventional ensemble-average-based methods, opto-digital molecular analytic approaches digitize detection by physically partitioning individual detection events into discrete compartments or directly locating and analyzing the signals from single molecules. The sensitivity can be enhanced by signal amplification reactions, signal enhancement interactions, labelling by strong signal emitters, advanced optics, image processing, and machine learning, while specificity can be improved by designing target-selective probes and profiling molecular dynamics. With the capabilities to attain a limit of detection several orders lower than the conventional methods, reveal intrinsic molecular information, and achieve multiplexed analysis using a small-volume sample, the emerging opto-digital molecular analytics may be revolutionarily instrumental to clinical diagnosis, molecular chemistry and science, drug discovery, and environment monitoring. In this article, we provide a comprehensive review of the recent advances, offer insights into the underlying mechanisms, give comparative discussions on different strategies, and discuss the current challenges and future possibilities.

Surface-Enhanced Raman Spectroscopy for Biomedical Applications: Recent Advances and Future Challenges

The year 2024 marks the 50th anniversary of the discovery of surface-enhanced Raman spectroscopy (SERS). Over recent years, SERS has experienced rapid development and became a critical tool in biomedicine with its unparalleled sensitivity and molecular specificity. This review summarizes the advancements and challenges in SERS substrates, nanotags, instrumentation, and spectral analysis for biomedical applications. We highlight the key developments in colloidal and solid SERS substrates, with an emphasis on surface chemistry, hotspot design, and 3D hydrogel plasmonic architectures. Additionally, we introduce recent innovations in SERS nanotags, including those with interior gaps, orthogonal Raman reporters, and near-infrared-II-responsive properties, along with biomimetic coatings. Emerging technologies such as optical tweezers, plasmonic nanopores, and wearable sensors have expanded SERS capabilities for single-cell and single-molecule analysis. Advances in spectral analysis, including signal digitalization, denoising, and deep learning algorithms, have improved the quantification of complex biological data. Finally, this review discusses SERS biomedical applications in nucleic acid detection, protein characterization, metabolite analysis, single-cell monitoring, and in vivo deep Raman spectroscopy, emphasizing its potential for liquid biopsy, metabolic phenotyping, and extracellular vesicle diagnostics. The review concludes with a perspective on clinical translation of SERS, addressing commercialization potentials and the challenges in deep tissue in vivo sensing and imaging.

Reversible Swell-Shrink Hydrogel Microspheres for High-Selectivity Digital SERS Analysis of Nonvolatile Fentanyl in Simulated Breath Aerosols

In clinical diagnostics, human breath presents an alternative and more convenient sample than biofluids for detecting the ingestion of nonvolatile drugs. Surface-enhanced Raman spectroscopy (SERS) is a powerful vibrational spectroscopy technique with high sensitivity based on molecular fingerprinting. However, the low affinity of traditional SERS substrates for aerosols and the stochastic fluctuation of the SERS signal at low concentrations limit their application in breath aerosol analysis. In this study, we synthesized hydrogel microsphere SERS substrates with highly reversible swelling/shrinking properties that enhance target analyte accumulation in breath aerosols and promote plasmonic nanoparticle aggregation for intense Raman hotspot formation. Furthermore, these hydrogel microsphere SERS substrates function as a three-in-one system, enabling multilevel selectivity based on size, charge, and hydrophilicity for target molecules simultaneously without pretreatment. Notably, by "digitizing" the SERS signal of each individual hydrogel microsphere and calculating the proportion of positive microspheres, the hydrogel microspheres can serve as a digital SERS platform that circumvents the low stability issues resulting from fluctuations in SERS signal intensity. Consequently, the digital SERS platform achieved a detection limit of 0.5 ppm for fentanyl in simulated breath aerosols. This innovative sensing strategy not only demonstrates a promising approach for screening nonvolatile drugs but also simplifies the sampling process, holding great potential for clinical diagnosis of breath aerosols.

Digital SERS immunoassay of Interleukin-6 based on Au@Ag-Au nanotags

Interleukin-6 (IL-6) is a crucial cytokine involved in inflammation and immune regulation. However, the detection of IL-6 with ultrasensitivity and high specificity remains a significant challenge due to the inherent complexity of biofluids. Herein, we present a digital surface enhanced Raman scattering (SERS) immunoassay using core-shell Au@Ag-Au nanotags for IL-6 detection with ultrasensitivity and high reliability. A low-cost silicon chip was functionalized as capture substrates, employing novel SERS nanotags that exhibit strong, robust and reproducible signals at single-nanoparticle resolution as the amplification element. We proposed two analytical methods to validate single-molecule events follow a Poisson distribution and to quantify protein biomarkers over a broad linear dynamic range, respectively. The strong alignment between theoretical and experimental results enhances the method's reliability. Our assay provides two readouts: colorimetric analysis by naked eyes for high concentrations (>1 ng/mL) and digital SERS analysis for low concentrations. Following method optimization, we obtained a linear range from 100 fg/mL to 1 ng/mL (R2 = 0.994) with a limit of detection (LOD) of 12.4 fg/mL, suitable for clinical applications. The method was tested for IL-6 quantification in healthy human serum and saliva, with recoveries from 92.4% to 105.3%. Finally, the immunoassay demonstrated strong consistency with the standard clinical laboratory method when tested with clinical serum samples. Thus, our proposed the digital SERS immunoassay is a promising tool for the precision clinical diagnosis of IL-6-related diseases or other conditions.

Rapid and Sensitive Detection of Mutations in SARS-CoV-2 by Surface-Enhanced Raman Spectroscopy

Since the outbreak of the novel coronavirus (SARS-CoV-2), the world has suffered significant losses. At present, the pneumonia disease caused by SARS-CoV-2 virus has not been eliminated, and SARS-CoV-2 has a high mutation rate, and its variant strains also have a high prevalence rate, which has always threatened the health of all mankind. This study aims to develop a rapid and sensitive method to complement existing SARS-CoV-2 diagnostic tools by utilizing surface-enhanced Raman spectroscopy (SERS) for the direct detection of the intrinsic SERS signal from the S proteins of SARS-CoV-2 and its variants (Omicron and Delta) within 5 min using a portable Raman spectrometer. The linear range of S protein detection of Wild-type, Omicron and Delta variants ranged from 1.0 × 10-7 to 1.0 × 10-3 g·mL-1, the limits of detection (LOD) were down to ∼10-8 g·mL-1 level. Our proposed method uses portable Raman spectrometer for direct detection, which is characterized by its simplicity, rapidity, portability, and wide applicability. It enables simultaneous detection of diverse mutated targets, thereby playing a pivotal role in the early diagnosis of viral diseases. Moreover, it holds promising prospects in the fields of chemistry, biology, and medicine.

Recent Plasmonic Gold- and Silver-Assisted Raman Spectra for Advanced SARS-CoV-2 Detection

COVID-19 has become one of the deadliest epidemics in the past years. In efforts to combat the deadly disease besides vaccines, drug therapies, and facemasks, significant focus has been on designing specific methods for the sensitive and accurate detection of SARS-CoV-2. Of these, surface-enhanced Raman scattering (SERS) is an attractive analytical tool for the identification of SARS-CoV-2. SERS is the phenomenon of enhancement of Raman intensity signals from molecular analytes anchored onto the surfaces of roughened plasmonic nanomaterials. This work gives an updated summary of plasmonic gold nanomaterials (AuNMs) and silver nanomaterials (AgNMs)-based SERS technologies to identify SARS-CoV-2. Due to extreme "hot spots" promoting higher electromagnetic fields on their surfaces, different shapes of AuNMs and AgNMs combined with Raman probes have been reviewed for enhancing Raman signals of probe molecules for quantifying the virus. It also reviews progress made recently in the design of certain specific Raman probe molecules capable of imparting characteristic SERS response/tags for SARS-CoV-2 detection.

Plasmonic nanoparticle sensors: current progress, challenges, and future prospects

Plasmonic nanoparticles (NPs) have played a significant role in the evolution of modern nanoscience and nanotechnology in terms of colloidal synthesis, general understanding of nanocrystal growth mechanisms, and their impact in a wide range of applications. They exhibit strong visible colors due to localized surface plasmon resonance (LSPR) that depends on their size, shape, composition, and the surrounding dielectric environment. Under resonant excitation, the LSPR of plasmonic NPs leads to a strong field enhancement near their surfaces and thus enhances various light-matter interactions. These unique optical properties of plasmonic NPs have been used to design chemical and biological sensors. Over the last few decades, colloidal plasmonic NPs have been greatly exploited in sensing applications through LSPR shifts (colorimetry), surface-enhanced Raman scattering, surface-enhanced fluorescence, and chiroptical activity. Although colloidal plasmonic NPs have emerged at the forefront of nanobiosensors, there are still several important challenges to be addressed for the realization of plasmonic NP-based sensor kits for routine use in daily life. In this comprehensive review, researchers of different disciplines (colloidal and analytical chemistry, biology, physics, and medicine) have joined together to summarize the past, present, and future of plasmonic NP-based sensors in terms of different sensing platforms, understanding of the sensing mechanisms, different chemical and biological analytes, and the expected future technologies. This review is expected to guide the researchers currently working in this field and inspire future generations of scientists to join this compelling research field and its branches.

Superhydrophobic nanocellulose-based self-assembled flexible SERS substrates for pesticide detection

Flexible surface-enhanced Raman scattering (SERS) substrates that provide simple sampling are helpful for the on-site detection of explosive contamination, pesticide residues on food surfaces, and water pollution in public spaces. Using superhydrophobic nanocellulose-based film as the support, 2D flexible SERS substrates that integrated sampling, enrichment, and detection were successfully fabricated via the solvent-induced evaporation method. This approach enabled the co-loading of two plasmonic nanoparticles with different sizes and shapes. A uniform and dense distribution of two-dimensional "hot spots" was created by the plasmonic nanoparticles' self-assembly on the hydrophobic substrate. By adjusting the loading ratio of Au-core/Ag-shell nanocubes and gold nanospheres, their synergistic effect optimized the "hot spots" structure and significantly increased the SERS signal intensity. Additionally, the hydrophobic property of the substrate allowed the target analytes to be concentrated throughout the drying process, significantly increasing the sensitivity of SERS detection. This flexible substrate can sensitively and accurately detect the pesticide residues of phosphorus and methyl parathion on apple peel with the detection limit of 10-7 g/L and relative standard deviation (RSD) less than 10 %. The high-performance SERS substrate has great potential for in-situ detection applications such as food safety and environmental monitoring.

Development and Biomedical Application of Non-Noble Metal Nanomaterials in SERS

Surface-enhanced Raman scattering (SERS) is vital in many fields because of its high sensitivity, fast response, and fingerprint effect. The surface-enhanced Raman mechanisms are generally electromagnetic enhancement (EM), which is mainly based on noble metals (Au, Ag, etc.), and chemical enhancement (CM). With more and more studies on CM mechanism in recent years, non-noble metal nanomaterial SERS substrates gradually became widely researched and applied due to their superior economy, stability, selectivity, and biocompatibility compared to noble metal. In addition, non-noble metal substrates also provide an ideal new platform for SERS technology to probe the mechanism of biomolecules. In this paper, we review the applications of non-noble metal nanomaterials in SERS detection for biomedical engineering in recent years. Firstly, we introduce the development of some more common non-noble metal SERS substrates and discuss their properties and enhancement mechanisms. Subsequently, we focus on the progress of the application of SERS detection of non-noble metal nanomaterials, such as analysis of biomarkers and the detection of some contaminants. Finally, we look forward to the future research process of non-noble metal substrate nanomaterials for biomedicine, which may draw more attention to the biosensor applications of non-noble metal nanomaterial-based SERS substrates.

Single-molecule detection of SARS-CoV-2 N protein on multilayered plasmonic nanotraps with surface-enhanced Raman spectroscopy

The spread of the SARS-CoV-2 virus has had an unprecedented impact, both by posing a serious risk to human health and by amplifying the burden on the global economy. The rapid identification of the SARS-CoV-2 virus has been crucial to preventing and controlling the spread of SARS-CoV-2 infections. In this study, we propose a multilayered plasmonic nanotrap (MPNT) device for the rapid identification of single particles of SARS-CoV-2 virus in ultra-high sensitivity by surface-enhanced Raman scattering (SERS). The MPNT device is composed of arrays of concentric cylindrical cavities with Ag/SiO2/Ag multilayers deposited on the top and at the bottom. By varying the diameter of the cylinders and the thickness of the multilayers, the resonant optical absorption and local electric field were optimized. The SERS enhancement factors of the proposed device are of the order of 108, which enable the rapid identification of SARS-CoV-2 N protein in concentrations as low as 1.25 × 10-15－12.5 × 10-15 g mL-1 within 1 min. The developed MPNT SERS device provides a label-free and rapid detection platform for SARS-CoV-2 virus. The general nature of the device makes it equally suitable to detect other infectious viruses.

Comparison of Gap-Enhanced Raman Tags and Nanoparticle Aggregates with Polarization Dependent Super-Resolution Spectral SERS Imaging

Strongly confined electric fields resulting from nanogaps within nanoparticle aggregates give rise to significant enhancement of surface-enhanced Raman scattering (SERS). Nanometer differences in gap sizes lead to drastically different confined field strengths; so much attention has been focused on the development and understanding of nanostructures with controlled gap sizes. In this work, we report a novel petal gap-enhanced Raman tag (GERT) consisting of a bipyramid core and a nitrothiophenol (NTP) spacer to support the growth of hundreds of small petals and compare its SERS emission and localization to a traditional bipyramid aggregate. To do this, we use super resolution spectral SERS imaging that simultaneously captures the SERS images and spectra while varying the incident laser polarization. Intensity fluctuations inherent of SERS enabled super resolution algorithms to be applied, which revealed subdiffraction limited differences in the localization with respect to polarization direction for both particles. Interestingly, however, only the traditional bipyramid aggregates experienced a strong polarization dependence in their SERS intensity and in the plasmon-induced conversion of NTP to dimercaptoazobenzene (DMAB), which was localized with nanometer precision to regions of intense electromagnetic fields. The lack of polarization dependence (validated through electromagnetic simulations) and surface reactions from the bipyramid-GERTs suggests that the emissions arising from the bipyramid-GERTs are less influenced by confined fields.

Digital Surface-Enhanced Raman Spectroscopy-Lateral Flow Test Dipstick: Ultrasensitive, Rapid Virus Quantification in Environmental Dust

This study introduces a novel surface-enhanced Raman spectroscopy (SERS)-based lateral flow test (LFT) dipstick that integrates digital analysis for highly sensitive and rapid viral quantification. The SERS-LFT dipsticks, incorporating gold-silver core-shell nanoparticle probes, enable pixel-based digital analysis of large-area SERS scans. Such an approach enables ultralow-level detection of viruses that readily distinguishes positive signals from background noise at the pixel level. The developed digital SERS-LFTs demonstrate limits of detection (LODs) of 180 fg for SARS-CoV-2 spike protein, 120 fg for nucleocapsid protein, and 7 plaque forming units for intact virus, all within <30 min. Importantly, digital SERS-LFT methods maintain their robustness and their LODs in the presence of indoor dust, thus underscoring their potential for accurate and reliable virus diagnosis and quantification in real-world environmental settings.

Recent Studies on Metal-Embedded Silica Nanoparticles for Biological Applications

Recently, silica nanoparticles (NPs) have attracted considerable attention as biocompatible and stable templates for embedding noble metals. Noble-metal-embedded silica NPs utilize the exceptional optical properties of novel metals while overcoming the limitations of individual novel metal NPs. In addition, the structure of metal-embedded silica NPs decorated with small metal NPs around the silica core results in strong signal enhancement in localized surface plasmon resonance and surface-enhanced Raman scattering. This review summarizes recent studies on metal-embedded silica NPs, focusing on their unique designs and applications. The characteristics of the metal-embedded silica NPs depend on the type and structure of the embedded metals. Based on this progress, metal-embedded silica NPs are currently utilized in various spectroscopic applications, serving as nanozymes, detection and imaging probes, drug carriers, photothermal inducers, and bioactivation molecule screening identifiers. Owing to their versatile roles, metal-embedded silica NPs are expected to be applied in various fields, such as biology and medicine, in the future.

Accurate Quantification and Imaging of Cellular Uptake Using Single-Particle Surface-Enhanced Raman Scattering

Understanding the uptake, distribution, and stability of gold nanoparticles (NPs) in cells is of fundamental importance in nanoparticle sensors and therapeutic development. Single nanoparticle imaging with surface-enhanced Raman spectroscopy (SERS) measurements in cells is complicated by aggregation-dependent SERS signals, particle inhomogeneity, and limited single-particle brightness. In this work, we assess the single-particle SERS signals of various gold nanoparticle shapes and the role of silica encapsulation on SERS signals to develop a quantitative probe for single-particle level Raman imaging in living cells. We observe that silica-encapsulated gap-enhanced Raman tags (GERTs) provide an optimized probe that can be quantifiable per voxel in SERS maps of cells. This approach is validated by single-particle inductively coupled mass spectrometry (spICP-MS) measurements of NPs in cell lysate post-imaging. spICP-MS also provides a means of measuring the tag stability. This analytical approach can be used not only to quantitatively assess nanoparticle uptake on the cellular level (as in previous digital SERS methods) but also to reliably image the subcellular distribution and to assess the stability of NPs in cells.

Advances in nanobiosensors during the COVID-19 pandemic and future perspectives for the post-COVID era

The unprecedented threat of the highly contagious virus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes exponentially increased infections of coronavirus disease 2019 (COVID-19), highlights the weak spots of the current diagnostic toolbox. In the midst of catastrophe, nanobiosensors offer a new opportunity as an alternative tool to fill a gap among molecular tests, rapid antigen tests, and serological tests. Nanobiosensors surpass the potential of antigen tests because of their enhanced sensitivity, thus enabling us to see antigens as stable and easy-to-access targets. During the first three years of the COVID-19 pandemic, a substantial number of studies have reported nanobiosensors for the detection of SARS-CoV-2 antigens. The number of articles on nanobiosensors and SARS-CoV-2 exceeds the amount of nanobiosensor research on detecting previous infectious diseases, from influenza to SARS-CoV and MERS-CoV. This unprecedented publishing pace also implies the significance of SARS-CoV-2 and the present pandemic. In this review, 158 studies reporting nanobiosensors for detecting SARS-CoV-2 antigens are collected to discuss the current challenges of nanobiosensors using the criteria of point-of-care (POC) diagnostics along with COVID-specific issues. These advances and lessons during the pandemic pave the way for preparing for the post-COVID era and potential upcoming infectious diseases.

Revolutionizing SARS-CoV-2 omicron variant detection: Towards faster and more reliable methods

The emergence of the highly contagious Omicron variant of SARS-CoV-2 has inflicted significant damage during the ongoing COVID-19 pandemic. This new variant's significant sequence changes and mutations in both proteins and RNA have rendered many existing rapid detection methods ineffective in identifying it accurately. As the world races to control the spread of the virus, researchers are urgently exploring new diagnostic strategies to specifically detect Omicron variants with high accuracy and sensitivity. In response to this challenge, we have compiled a comprehensive overview of the latest reported rapid detection techniques. These techniques include strategies for the simultaneous detection of multiple SARS-CoV-2 variants and methods for selectively distinguishing Omicron variants. By categorizing these diagnostic techniques based on their targets, which encompass protein antigens and nucleic acids, we aim to offer a comprehensive understanding of the utilization of various recognition elements in identifying these targets. We also highlight the advantages and limitations of each approach. Our work is crucial in providing a more nuanced understanding of the challenges and opportunities in detecting Omicron variants and emerging variants.

Diagnostics and analysis of SARS-CoV-2: current status, recent advances, challenges and perspectives

The disastrous spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has induced severe public healthcare issues and weakened the global economy significantly. Although SARS-CoV-2 infection is not as fatal as the initial outbreak, many infected victims suffer from long COVID. Therefore, rapid and large-scale testing is critical in managing patients and alleviating its transmission. Herein, we review the recent advances in techniques to detect SARS-CoV-2. The sensing principles are detailed together with their application domains and analytical performances. In addition, the advantages and limits of each method are discussed and analyzed. Besides molecular diagnostics and antigen and antibody tests, we also review neutralizing antibodies and emerging SARS-CoV-2 variants. Further, the characteristics of the mutational locations in the different variants with epidemiological features are summarized. Finally, the challenges and possible strategies are prospected to develop new assays to meet different diagnostic needs. Thus, this comprehensive and systematic review of SARS-CoV-2 detection technologies may provide insightful guidance and direction for developing tools for the diagnosis and analysis of SARS-CoV-2 to support public healthcare and effective long-term pandemic management and control.