SARS-CoV-2 Virus Detection Via a Polymeric Nanochannel-Based Electrochemical Biosensor

Construction of Biomimetic Nanochannel, Property Regulation, and Biomarker Detection

The significance of biomimetic nanochannel in the field of biosensors is gaining increasing recognition. The controllable construction of biomimetic nanochannels and their performance modulation have demonstrated great importance and obtained wide interest. The nanochannels offer high sensitivity, enabling sensors to swiftly identify target biomarkers in complex biological samples, with detection limits reaching the picomolar level. Furthermore, they demonstrate exceptional selectivity and reproducibility, making them ideal tools for biomarker detection. In recent years, biosensors utilizing biomimetic nanochannel have shown remarkable performance in detecting a wide range of biomarkers. This review aims to explore the opportunities and challenges associated with biomimetic nanochannel technology in biosensor applications, focusing on the construction and performance modulation of these nanochannels, as well as their applications in detecting nucleic acids, proteins, organisms, and small molecules. Providing forward-looking insights into this cutting-edge field is aspired, with particular emphasis on technological advancements, addressing current challenges, and discussing future trends.

Block copolymer-assembled nanopore arrays enable ultrasensitive label-free DNA detection

DNA detection via nanoporous-based electrochemical biosensors is a promising method for rapid pathogen identification and disease diagnosis. These sensors detect electrical current variations caused by DNA hybridization in a nanoporous layer on an electrode. Current fabrication techniques for the typically micrometers-thick nanoporous layer often suffer from insufficient control over nanopore dimensions and involve complex fabrication steps, including handling and stacking of a brittle porous membrane. Here, we introduce a bottom-up fabrication process based on the self-assembly of high molecular weight block copolymers with sol-gel precursors to create an inorganic nanoporous thin film directly on electrode surfaces. This approach eliminates the need for elaborate manipulation of the nanoporous membrane, provides fine control over the structural features, and enables surface modification with DNA capture probes. Using this nanoarchitecture with a thickness of 150 nm, we detected DNA sequences derived from 16S rRNA gene fragments of the E. coli genome electrochemically in less than 20 minutes, achieving a limit of detection of 30 femtomolar (fM) and a limit of quantification of 500 fM. This development marks a significant step towards a portable, rapid, and accurate DNA detection system.

Antibody screening-assisted multichannel nanoplasmonic sensing chip based on SERS for viral screening and variants identification

The Omicron variants of SARS-CoV-2 have been spreading globally and have never disappeared from our sight, indicating that their coexistence with humans has become a fact, and monitoring its evolution and spread remains a current task. Although polymerase chain reaction (PCR) is the most commonly used virus detection method, it requires labor-intensive and time-consuming procedures in a laboratory setting. Herein, a multichannel nanoplasmonic sensing chip based on surface enhanced Raman spectroscopy (SERS) was developed for detecting N and S proteins, as well as IgG and IgM, related to SARS-CoV-2 Omicron variants. Through a self-screening process, specific antibodies for on-site and rapid identification of important variants of concern (VoCs) were obtained, and their binding was confirmed by protein structure analysis. The use of these S protein specific antibodies can accurately identify Omicron VoCs (BA. 5, BF.7，XBB.1.5) with the detection limit (LoD) of 0.16 pg/mL. Then, the proposed SERS array chip was integrated with a hand-held Raman spectrometer to successfully detect the Omicron subvariants in real saliva samples within only 20 min, greatly reducing the detection time of PCR. This sensing technology will provide a powerful and rapid point-of-care testing (POCT) method for virus diagnosis, subtype identification, and post-infection antibody level monitoring.

Development of immunochromatographic and homogeneous assay based on quantum dot-functionalized polystyrene nanoprobes for the qualitative and quantitative screening of respiratory viruses

Accurately differentiating respiratory diseases caused by viruses is challenging because of the similarity in their early or clinical symptoms. Moreover, different infection sources require different treatments. However, the current diagnostic methods have limited differentiating efficiency and sensitivity. We developed a dual-system immunosensor with a bilayer fluorescent label as a signal amplifier for the on-site, sensitive, and accurate identification of multiple respiratory viruses (RVs). The nanomaterial, comprising a polystyrene (PS) nanosphere core encapsulated by two layers of CdSe@ZnS-COOH quantum dots (QDs), outperforms the conventional color and fluorescent labels in RV detection. The dual-system detection platform, comprising a PS@DQD-based lateral flow immunoassay (LFIA) and a PS@DQD-based homogeneous sensor, enables qualitative and quantitative screening of multiple respiratory viruses within 10 and 30 min, respectively, depending on the specific detection requirements for different application scenarios. This remarkable method provides 51.2 to 1000 times sensitivity improvement over commercial antigen detection kits and greater than 12.5 to 100 times improvement over QD-based immunosensors. Furthermore, we comprehensively evaluated the specificity, reproducibility, and stability of the integrated dual-system detection platform, demonstrating its reliability. Remarkably, the respiratory viral testing was validated using biological samples, thus illustrating its promise and convenience in the detection of respiratory viruses.

Digital Quantification and Ultrasensitive Detection of Single Influenza Virus Using Microgel-in-Droplet Enzyme-Linked Immunosorbent Assay

Detection and quantification of viral particles (VPs) facilitate both diagnostics of pathogenic viruses and quality control testing of virus-based products. However, existing technologies fail to afford concurrent ultrasensitive detection and large-scale absolute quantification of VPs. Here, we propose a digital Microgel-in-Droplet enzyme-linked immunosorbent assay (ELISA) system that enables the processing and monitoring of millions of ELISA reactions at the single-VP level by incorporating droplet microfluidics with sandwich ELISA. Upon validating the microfluidic workflow and optimizing ELISA parameters, we demonstrate ultrasensitive VP detection at a limit of detection of 56 PFU/test. Leveraging a fluorescence-based screening platform, we further realize high-throughput digital counting of VPs with a linear detection range of 500-64 000 PFU/test. The precision is comparable to that of the gold standard, the plaque assay, across a wide range of virus concentrations. We anticipate that our system will provide a novel paradigm for the absolute enumeration of various types of viral particles.

Recent Advances of Food Hazard Detection Based on Artificial Nanochannel Sensors

Food quality and safety are related to the health and safety of people, and food hazards are important influencing factors affecting food safety. It is strongly necessary to develop food safety rapid detection technology to ensure food safety. As a new detection technology, artificial nanochannel-based electrochemical and other methods have the advantages of being real-time, simple, and sensitive and are widely used in the detection of food hazards. In this paper, we review artificial nanochannel sensors as a new detection technology in food safety for different types of food hazards: biological hazards (bacteria, toxins, viruses) and chemical hazards (heavy metals, organic pollutants, food additives). At the same time, we critically discuss the advantages and disadvantages of artificial nanochannel sensor detection, as well as the restrictions and solutions of detection, and finally look forward to the challenges and development prospects of food safety detection technology based on the limitations of artificial nanochannel detection. We expect to provide a theoretical basis and inspiration for the development of rapid real-time detection technology for food hazards and the production of portable detection equipment in the future.

A Semi-Automatic Environmental Monitoring Device for Mercury and Cobalt Ion Detection

A syringe-based, semi-automatic environmental monitoring device is developed for on-site detection of harmful heavy metal ions in water. This portable device consists of a spring-embedded syringe and a polydimethylsiloxane (PDMS) membrane-based flow regulator for semi-automatic fix-and-release fluidic valve actuation, and a paper-based analytical device (PAD) with two kinds of gold nanoclusters (AuNCs) for sensitive Hg2+ and Co2+ ion detection, respectively. The thickness of the elastic PDMS membrane can be adjusted to stabilize and modulate the flow rates generated by the pushing force provided by the spring attached to the plunger. Also, different spring constants can drastically alter the response time. People of all ages can extract the fix-volume sample solutions and then release them to automatically complete the detection process, ensuring high reliability and repeatability. The PAD comprises two layers of modified paper, and each layer is immobilized with bovine serum albumin-capped gold nanoclusters (R-AuNCs) and glutathione-capped gold clusters (G-AuNCs), respectively. The ligands functionalized on the surface of the AuNCs not only can fine-tune the optical properties of the nanoclusters but also enable specific and simultaneous detection of Hg2+ and Co2+ ions via metallophilic Au+ -Hg2+ interaction and the Co2+ -thiol complexation effect, respectively. The feasibility of the device for detecting heavy metal ions at low concentrations in various environmental water samples is demonstrated. The Hg2+ and Co2+ ions can be seen simultaneously within 20 min with detection limits as low as 1.76 nm and 0.27 µm, respectively, lower than those of the regulatory restrictions on water by the US Environmental Protection Agency and the European Union. we expect this sensitive, selective, portable, and easy-to-use device to be valid for on-site multiple heavy metal ion pollution screenings in resource-constrained settings.

Nanomaterial surface modification toolkit: Principles, components, recipes, and applications

Surface-functionalized nanostructures are at the forefront of biotechnology, providing new opportunities for biosensors, drug delivery, therapy, and bioimaging applications. The modification of nanostructures significantly impacts the performance and success of various applications by enabling selective and precise targeting. This review elucidates widely practiced surface modification strategies, including click chemistry, cross-coupling, silanization, aldehyde linkers, active ester chemistry, maleimide chemistry, epoxy linkers, and other protein and DNA-based methodologies. We also delve into the application-focused landscape of the nano-bio interface, emphasizing four key domains: therapeutics, biosensing, environmental monitoring, and point-of-care technologies, by highlighting prominent studies. The insights presented herein pave the way for further innovations at the intersection of nanotechnology and biotechnology, providing a useful handbook for beginners and professionals. The review draws on various sources, including the latest research articles (2018-2023), to provide a comprehensive overview of the field.

Toward waterborne protozoa detection using sensing technologies

Drought and limited sufficient water resources will be the main challenges for humankind during the coming years. The lack of water resources for washing, bathing, and drinking increases the use of contaminated water and the risk of waterborne diseases. A considerable number of waterborne outbreaks are due to protozoan parasites that may remain active/alive in harsh environmental conditions. Therefore, a regular monitoring program of water resources using sensitive techniques is needed to decrease the risk of waterborne outbreaks. Wellorganized point-of-care (POC) systems with enough sensitivity and specificity is the holy grail of research for monitoring platforms. In this review, we comprehensively gathered and discussed rapid, selective, and easy-to-use biosensor and nanobiosensor technologies, developed for the early detection of common waterborne protozoa.