Magnetophoretic slider assay for electrochemical detection of SARS-cov-2 nucleocapsid protein in nasal swab samples.

The COVID-19 pandemic highlighted the need for rapid and sensitive diagnostic tools. In this work, the Magnetophoretic Slider Assay (MeSA) was integrated with electrochemical detection (eMeSA) using screen-printed carbon electrodes for the first time for the detection of SARS-CoV-2 nucleocapsid protein (NP). A sandwich enzyme-linked immunosorbent assay (ELISA) was performed on streptavidin-labeled magnetic beads (MBs).

Multiplexed Capillary-Flow Driven Immunoassay for Respiratory Illnesses.

Multiplexed analysis in medical diagnostics is widely accepted as a more thorough and complete method compared to single-analyte detection. While analytical methods like polymerase chain reaction and enzyme-linked immunosorbent assay (ELISA) exist for multiplexed detection of biomarkers, they remain time-consuming and expensive. Lateral flow assays (LFAs) are an attractive option for point-of-care testing, and examples of multiplexed LFAs exist.

Capillary flow-driven immunoassay platform for COVID-19 antigen diagnostics.

Over the last few years, the SARS-CoV-2 pandemic has made the need for rapid, affordable diagnostics more compelling than ever. While traditional laboratory diagnostics like PCR and well-plate ELISA are sensitive and specific, they can be costly and take hours to complete. Diagnostic tests that can be used at the point-of-care or at home, like lateral flow assays (LFAs) are a simple, rapid alternative, but many commercially available LFAs have been criticized for their lack of sensitivity compared to laboratory methods like well-plate ELISAs.

Capillary driven microfluidic sequential flow device for point-of-need ELISA: COVID-19 serology testing.

A capillary-driven microfluidic sequential flow device, designed for eventual at-home or doctor's office use, was developed to perform an enzyme-linked immunosorbent assay (ELISA) for serology assays. Serology assays that detect SARS-CoV-2 antibodies can be used to determine prior infection, immunity status, and/or individual vaccination status and are typically run using well-plate ELISAs in centralized laboratories, but in this format SARs-CoV-2 serology tests are too expensive and/or slow for most situations. Instead, a point-of-need device that can be used at home or in doctor's offices for COVID-19 serology testing would provide critical information for managing infections and determining immune status.

Electrochemical Capillary Driven Immunoassay for Detection of SARS-CoV-2.

The COVID-19 pandemic focused attention on a pressing need for fast, accurate, and low-cost diagnostic tests. This work presents an electrochemical capillary driven immunoassay (eCaDI) developed to detect SARS-CoV-2 nucleocapsid (N) protein. The low-cost flow device is made of polyethylene terephthalate (PET) and adhesive films.

Progress toward a Simplified UTI Diagnostic: Pump-Free Magnetophoresis for E. coli Detection.

Urinary tract infections (UTIs) are one of the most common infections across the world and can lead to serious complications such as sepsis if not treated in a timely manner. Uropathogenic account for 75% of all UTIs. Early diagnosis is crucial to help control UTIs, but current culturing methods are expensive and time-consuming and lack sensitivity.

Electrochemical Immunoassay for the Detection of SARS-CoV-2 Nucleocapsid Protein in Nasopharyngeal Samples.

Point-of-care (POC) methods currently available for detecting SARS-CoV-2 infections still lack accuracy. Here, we report the development of a highly sensitive electrochemical immunoassay capable of quantitatively detecting the presence of the SARS-CoV-2 virus in patient nasopharyngeal samples using stencil-printed carbon electrodes (SPCEs) functionalized with capture antibodies targeting the SARS-CoV-2 nucleocapsid protein (N protein). Samples are added to the electrode surface, followed by horseradish peroxidase (HRP)-conjugated detection antibodies also targeting the SARS-CoV-2 N protein.

Electrochemical Capillary-Flow Immunoassay for Detecting Anti-SARS-CoV-2 Nucleocapsid Protein Antibodies at the Point of Care.

Rapid and inexpensive serological tests for SARS-CoV-2 antibodies are needed to conduct population-level seroprevalence surveillance studies and can improve diagnostic reliability when used in combination with viral tests. Here, we report a novel low-cost electrochemical capillary-flow device to quantify IgG antibodies targeting SARS-CoV-2 nucleocapsid proteins (anti-N antibody) down to 5 ng/mL in low-volume (10 μL) human whole blood samples in under 20 min. No sample preparation is needed as the device integrates a blood-filtration membrane for on-board plasma extraction.

Padlock probe-based rolling circle amplification lateral flow assay for point-of-need nucleic acid detection.

Sensitive, reliable and cost-effective detection of pathogens has wide ranging applications in clinical diagnostics and therapeutics, water and food safety, environmental monitoring, biosafety and epidemiology. Nucleic acid amplification tests (NAATs) such as PCR and isothermal amplification methods provide excellent analytical performance and significantly faster turnaround times than conventional culture-based methods. However, the inherent cost and complexity of NAATs limit their application in resource-limited settings and the developing world.

Flow control in a laminate capillary-driven microfluidic device.

Capillary-driven microfluidic devices are of significant interest for on-site analysis because they do not require external pumps and can be made from inexpensive materials. Among capillary-driven devices, those made from paper and polyester film are among the most common and have been used in a wide array of applications. However, since capillary forces are the only driving force, flow is difficult to control, and passive flow control methods such as changing the geometry must be used to accomplish various analytical applications.

Paper-based pump-free magnetophoresis.

Microfluidic magnetophoresis is a powerful technique that is used to separate and/or isolate cells of interest from complex matrices for analysis. However, mechanical pumps are required to drive flow, limiting portability and making translation to point-of-care (POC) settings difficult. Microfluidic paper-based analytical devices (μPADs) offer an alternative to traditional microfluidic devices that do not require external pumps to generate flow.

Paper-based nuclease protection assay with on-chip sample pretreatment for point-of-need nucleic acid detection.

Pathogen detection is crucial for human, animal, and environmental health; crop protection; and biosafety. Current culture-based methods have long turnaround times and lack sensitivity. Nucleic acid amplification tests offer high specificity and sensitivity.

The Fluctuating Cell-Specific Light Environment and Its Effects on Cyanobacterial Physiology.

Individual cells of cyanobacteria or algae are supplied with light in a highly irregular fashion when grown in industrial-scale photobioreactors (PBRs). These conditions coincide with significant reductions in growth rate compared to the static light environments commonly used in laboratory experiments. We grew a dense culture of the model cyanobacterium sp.

Multilayered Microfluidic Paper-Based Devices: Characterization, Modeling, and Perspectives.

Microfluidic paper-based analytical devices (μPADs) are simple but powerful analytical tools that are gaining significant recent attention due to their many advantages over more traditional monitoring tools. These include being inexpensive, portable, pump-free, and having the ability to store reagents. One major limitation of these devices is slow flow rates, which are controlled by capillary action in the hydrophilic pores of cellulosic paper.

An ultra-sensitive capacitive microwire sensor for pathogen-specific serum antibody responses.

Detection of viral infection is commonly performed using serological techniques like the enzyme-linked immunosorbent assay (ELISA) to detect antibody responses. Such assays may also be used to determine the infection phase based on isotype prevalence. However, ELISAs demonstrate limited sensitivity and are difficult to perform at the point of care.

Development of an Electrochemical Paper-Based Analytical Device for Trace Detection of Virus Particles.

Viral pathogens are a serious health threat around the world, particularly in resource limited settings, where current sensing approaches are often insufficient and slow, compounding the spread and burden of these pathogens. Here, we describe a label-free, point-of-care approach toward detection of virus particles, based on a microfluidic paper-based analytical device with integrated microwire Au electrodes. The device is initially characterized through capturing of streptavidin modified nanoparticles by biotin-modified microwires.

Rapid flow in multilayer microfluidic paper-based analytical devices.

Microfluidic paper-based analytical devices (μPADs) are a versatile and inexpensive point-of-care (POC) technology, but their widespread adoption has been limited by slow flow rates and the inability to carry out complex in field analytical measurements. In the present work, we investigate multilayer μPADs as a means to generate enhanced flow rates within self-pumping paper devices. Through optical and electrochemical measurements, the fluid dynamics are investigated and compared to established flow theories within μPADs.

High-Throughput Inertial Focusing of Micrometer- and Sub-Micrometer-Sized Particles Separation.

The ability to study individual bacteria or subcellular organelles using inertial microfluidics is still nascent. This is due, in no small part, to the significant challenges associated with concentrating and separating specific sizes of micrometer and sub-micrometer bioparticles in a microfluidic format. In this study, using a rigid polymeric microfluidic network with optimized microchannel geometry dimensions, it is demonstrated that 2 µm, and even sub-micrometer, particles can be continuously and accurately focused to stable equilibrium positions.

A sensitive DNA capacitive biosensor using interdigitated electrodes.

This paper presents a label-free affinity-based capacitive biosensor using interdigitated electrodes. Using an optimized process of DNA probe preparation to minimize the effect of contaminants in commercial thiolated DNA probe, the electrode surface was functionalized with the 24-nucleotide DNA probes based on the West Nile virus sequence (Kunjin strain). The biosensor has the ability to detect complementary DNA fragments with a detection limit down to 20 DNA target molecules (1.

Spatially resolved electrochemical sensing of chemical gradients.

Chemical gradients drive a diverse set of biological processes ranging from nerve transduction to ovulation. At present, the most common method for quantifying chemical gradients is microscopy. Here, a new concept for probing spatial and temporal chemical gradients is reported that uses a multi-layer microfluidic device to measure analyte concentration as a function of lateral position in a microfluidic channel using electrochemistry in a format that is readily adaptable to multi-analyte sensing.

Mapping spatiotemporal molecular distributions using a microfluidic array.

The spatial and temporal distributions of an extensive number of diffusible molecules drive a variety of complex functions. These molecular distributions often possess length scales on the order of a millimeter or less; therefore, microfluidic devices have become a powerful tool to study the effects of these molecular distributions in both chemical and biological systems. Although there exist a number of studies utilizing microdevices for the creation of molecular gradients, there are few, if any, studies focusing on the measurement of spatial and temporal distributions of molecular species created within the study system itself.

Fiber optic monooxygenase biosensor for toluene concentration measurement in aqueous samples.

Measurements of pollutants such as toluene are critical for the characterization of contaminated sites and for the monitoring of remediation processes and wastewater treatment effluents. Fiber optic enzymatic biosensors have the potential to provide cost-effective, real time, continuous, in situ measurements. In this study, a fiber optic enzymatic biosensor was constructed and characterized for the measurement of toluene concentrations in aqueous solutions.

An optical waveguide array biosensor for serology - biomed 2010.

A label-free optical waveguide immunosensor was designed, fabricated and tested. Different from other popular resonance-based biosensors, such as surface-plasmon-resonance (SPR) or ring/disk resonance biosensors, the local evanescent array coupled (LEAC) biosensor relies on a local evanescent field shift mechanism and can be readily manufactured using trailing-edge integrated-circuit technology with chip-scale microfluidics technology to provide very low cost. The anticipated final form of the sensor technology will require no external equipment enabling disposable use for point-of-care disease detection in non-traditional health-care settings.

Optical and physical characterization of a local evanescent array coupled biosensor: Use of evanescent field perturbations for multianalyte sensing.

The evanescent field surrounding the core of an optical waveguide is very sensitive to refractive index changes near the core. This sensitivity can be exploited to form the basis for a quantitative sensor with high specificity and sensitivity. Selective probe molecules may be attached to the surface of a waveguide core and the evanescent field locally monitored as target analytes are introduced to the system.