Recent advances in immunodiagnostics based on biosensor technologies-from central laboratory to the point of care

COVID-19 cooling: Nanostrategies targeting cytokine storm for controlling severe and critical symptoms

As severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants continue to wreak havoc worldwide, the "Cytokine Storm" (CS, also known as the inflammatory storm) or Cytokine Release Syndrome has reemerged in the public consciousness. CS is a significant contributor to the deterioration of infected individuals. Therefore, CS control is of great significance for the treatment of critically ill patients and the reduction of mortality rates. With the occurrence of variants, concerns regarding the efficacy of vaccines and antiviral drugs with a broad spectrum have grown. We should make an effort to modernize treatment strategies to address the challenges posed by mutations. Thus, in addition to the requirement for additional clinical data to monitor the long-term effects of vaccines and broad-spectrum antiviral drugs, we can use CS as an entry point and therapeutic target to alleviate the severity of the disease in patients. To effectively combat the mutation, new technologies for neutralizing or controlling CS must be developed. In recent years, nanotechnology has been widely applied in the biomedical field, opening up a plethora of opportunities for CS. Here, we put forward the view of cytokine storm as a therapeutic target can be used to treat critically ill patients by expounding the relationship between coronavirus disease 2019 (COVID-19) and CS and the mechanisms associated with CS. We pay special attention to the representative strategies of nanomaterials in current neutral and CS research, as well as their potential chemical design and principles. We hope that the nanostrategies described in this review provide attractive treatment options for severe and critical COVID-19 caused by CS.

Portable biosensor-based oral pathogenic bacteria detection for community and family applications

Detection of oral pathogens is essential in the management of oral diseases, as their occurrence and progression are closely linked to an imbalance in these microorganisms. Detection techniques such as microbial cultures, enzyme-linked immunosorbent assays and polymerase chain reactions are highly dependent on complex testing procedures and specialized laboratory equipment, making prevention and early diagnosis of oral diseases difficult. To comprehensively implement oral disease prevention and early diagnosis in social groups, there is an urgent need for portable testing methods for oral pathogenic bacteria that can be applied in community and home settings. In this review, several common portable biosensors for pathogenic bacteria are first described. Based on the goal of achieving primary prevention and diagnosis of oral diseases, we elaborate and summarize portable biosensors for common oral pathogenic bacteria in terms of how to achieve portability of the technique. This review aims to reflect the current status of portable biosensors for common oral pathogens and to lay the foundation for the further realization of portable detection of oral pathogens.

Molecular Computation for Molecular Classification

DNA as an informational polymer has, for the past 30 years, progressively become an essential molecule to rationally build chemical reaction networks endowed with powerful signal-processing capabilities. Whether influenced by the silicon world or inspired by natural computation, molecular programming has gained attention for diagnosis applications. Of particular interest for this review, molecular classifiers have shown promising results for disease pattern recognition and sample classification. Because both input integration and computation are performed in a single tube, at the molecular level, this low-cost approach may come as a complementary tool to molecular profiling strategies, where all biomarkers are quantified independently using high-tech instrumentation. After introducing the elementary components of molecular classifiers, some of their experimental implementations are discussed either using digital Boolean logic or analog neural network architectures.

Progression of Paper-Based Point-of-Care Testing toward Being an Indispensable Diagnostic Tool in Future Healthcare

Point-of-care (POC) diagnostics in particular focuses on the timely identification of harmful conditions close to the patients' needs. For future healthcare these diagnostics could be an invaluable tool especially in a digitalized or telemedicine-based system. However, while paper-based POC tests, with the most prominent example being the lateral flow assay (LFA), have been especially successful due to their simplicity and timely response, the COVID-19 pandemic highlighted their limitations, such as low sensitivity and ambiguous responses. This perspective discusses strategies that are currently being pursued to evolve such paper-based POC tests toward a superior diagnostic tool that provides high sensitivities, objective result interpretation, and multiplexing options. Here, we pinpoint the challenges with respect to (i) measurability and (ii) public applicability, exemplified with select cases. Furthermore, we highlight promising endeavors focused on (iii) increasing the sensitivity, (iv) multiplexing capability, and (v) objective evaluation to also ready the technology for integration with machine learning into digital diagnostics and telemedicine. The status quo in academic research and industry is outlined, and the likely highly relevant role of paper-based POC tests in future healthcare is suggested.

Organic Light-Emitting Diode Based Fluorescence-Linked Immunosorbent Assay for SARS-CoV-2 Antibody Detection

Immunodiagnostics have been widely used in the detection of disease biomarkers. The conventional immunological tests in central laboratories require expensive equipment and, for non-specialists, the tests are technically demanding and time-consuming, which has prevented their use by the public. Thus, point-of-care tests (POCT), such as lateral flow immunoassays, are being, or have been, developed as more convenient and low-cost methods for immunodiagnostics. However, the sensitivity of such tests is often a concern. Here, a fluorescence-linked immunosorbent assay (FLISA) using organic light-emitting diodes (OLEDs) as excitation light sources was investigated as a way forward for the development of compact and sensitive POCTs. Phycoerythrin (PE) was selected as the fluorescent dye, and OLEDs were designed with different emission spectra. The leakage light of different OLEDs for exciting PE was then investigated to reduce the background noise and improve the sensitivity of the system. Finally, as proof-of-principle that OLED-based technology can be successfully further developed for POCT, antibodies to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in human serum was detected by OLED-FLISA.

Electrochemical DNA sensors for drug determination

In this review, recent achievements in the development of the DNA biosensors developed for the drug determination have been presented with particular emphasis to the main principles of their assembling and signal measurement approaches. The design of the DNA sensors is considered with characterization of auxiliary components and their necessity for the biosensor operation. Carbon nanomaterials, metals and their complexes as well as electropolymerized polymers are briefly described in the assembly of DNA sensors. The performance of the DNA sensors is summarized within 2017-2022 for various drugs and factors influencing the sensitivity and selectivity of the response are discussed. Special attention is paid to the mechanism of the signal generation and possible drawbacks in the analysis of real samples.

Low-cost, point-of-care biomarker quantification

Low-cost, point-of-care (POC) devices that allow fast, on-site disease diagnosis could have a major global health impact, particularly if they can provide quantitative measurement of molecules indicative of a diseased state (biomarkers). Accurate quantification of biomarkers in patient samples is already challenging when research-grade, sophisticated equipment is available; it is even more difficult when constrained to simple, cost-effective POC platforms. Here, we summarize the main challenges to accurate, low-cost POC biomarker quantification. We also review recent efforts to develop and implement POC tools beyond qualitative readouts, and we conclude by identifying important future research directions.

Detection of Carbohydrate Antigen 50 Based on a Novel Miniaturized Chemiluminescence Analyzer Enables Large-Scale Cancer Early Screening in Grassroots Community

Early screening of cancer can effectively prolong survival time and reduce cancer mortality. However, the existing health-monitoring devices can only be carried out in professional laboratories, so large-scale early cancer screening in resource-limited settings is hardly achieved. To embrace the challenge, we developed a novel chemiluminescence immunoassay (CLIA) analyzer that does not require a professional operation. Then, it was applied to detect carbohydrate antigen 50 (CA50), a non–organ-specific tumor marker for screening various cancers. As a result, the analyzer exhibited excellent performance that the total assay time was only 15 min, and the detection limit reached 0.057 U ml⁻¹. A coefficient of variance (CV) less than 15% was well-controlled for both intra- and inter-assay precision, and the linear range was 0–500 U ml⁻¹. More importantly, this analyzer can continuously detect 60 samples per hour without any professional paramedic. Finally, this analyzer has been applied to evaluate clinical samples and the detected results showed a good correlation with the clinical test results (correlation coefficient, 0.9958). These characteristics exactly meet large-scale and high-throughput early screening of cancer. Thus, this miniaturized analyzer for CA50 detection is promising to achieve early large-scale screening of cancer in the resource-limited grassroots community.

A low-cost, portable, and practical LAMP device for point-of-diagnosis in the field

Transition of rapid, ready-to-use, and low-cost nucleic acid-based detection technologies from laboratories to points of sample collection has drastically accelerated. However, most of these approaches are still incapable of diagnosis starting from sampling, through nucleic acid isolation and detection in the field. Here, we developed a simple, portable, low-cost, colorimetric, and remotely controllable platform for reliable, high-throughput, and rapid diagnosis using loop mediated isothermal amplification (LAMP) assays. It consists of a thermally isolated cup, low-cost electronic components, a polydimethylsiloxane sample well, and a fast prototyped case that covers electronic components. The steady-state temperature error of the system is less than 1%. We performed LAMP, Colony-LAMP, and Colony PCR reactions using the yaiO₂ primer set for Escherichia coli and Pseudomonas aeruginosa samples at 65˚C and 30 min. We detected the end-point colorimetric readouts by the naked eye under day light. We confirmed the specificity and sensitivity of our approach using pure genomic DNA and crude bacterial colonies. We benchmarked our Colony-LAMP detection against Colony PCR. The number of samples tested can easily be modified for higher throughput in our system. We strongly believe that our platform can greatly contribute rapid and reliable diagnosis in versatile operational environments. This article is protected by copyright. All rights reserved.

An integrated device for fast and sensitive immunosuppressant detection

The present paper describes a compact point of care (POC) optical device for therapeutic drug monitoring (TDM). The core of the device is a disposable plastic chip where an immunoassay for the determination of immunosuppressants takes place. The chip is designed in order to have ten parallel microchannels allowing the simultaneous detection of more than one analyte with replicate measurements. The device is equipped with a microfluidic system, which provides sample mixing with the necessary chemicals and pumping samples, reagents and buffers into the measurement chip, and with integrated thin film amorphous silicon photodiodes for the fluorescence detection. Submicrometric fluorescent magnetic particles are used as support in the immunoassay in order to improve the efficiency of the assay. In particular, the magnetic feature is used to concentrate the antibody onto the sensing layer leading to a much faster implementation of the assay, while the fluorescent feature is used to increase the optical signal leading to a larger optical dynamic change and consequently a better sensitivity and a lower limit of detection. The design and development of the whole integrated optical device are here illustrated. In addition, detection of mycophenolic acid and cyclosporine A in spiked solutions and in microdialysate samples from patient blood with the implemented device are reported.

Flexible Microwave Biosensor for Skin Abnormality Detection Based on Spoof Surface Plasmon Polaritons

Point-of-care testing plays an important role in the detection of skin abnormalities. The detection of skin abnormalities requires sufficient depth and no harm. A flexible microwave biosensor based on spoof surface plasmon polaritons was designed to meet the requirements of skin abnormalities. The designed biosensor, which works at 11.3 GHz, is small and can be flexibly attached to the skin surface of any part of the human body for measurement. The health status of the skin can be evaluated by the resonant frequency and the magnitude of the reflection coefficient of the sensor. The sensor was tested on pork skin. The experiment results showed that the sensor can detect skin abnormalities such as skin burn, skin tumor, and others. Compared with other sensors, the sensor has sufficient penetration depth because of the strong penetration of microwave electromagnetic waves. It is the first flexible microwave biosensor used for skin, which involves point-of-care testing, and continuous monitoring of skin.

Study on Factors Affecting the Performance of a CRISPR/Cas-Assisted New Immunoassay: Detection of Salivary Insulin as an Example

The clustered regularly interspaced short palindromic repeat (CRISPR)/Cas is now playing a significant role in biosensing applications, especially when the trans-cleavage activity of several Cas effectors is discovered. Taking advantages of both CRISPR/Cas and the enzyme-linked immunosorbent assay (ELISA) in analytical and clinical investigations, CRISPR/Cas-powered ELISA has been successfully designed to detect a spectrum of analytes beyond nucleic acid. Herein, we developed a CRISPR/Cas12a-assisted new immunoassay (CANi) for detection of salivary insulin as an example. Specifically, factors (antibody selection, temperature, and assay time) affecting the CRISPR/Cas-based ELISA system's performance were investigated. It was observed that the concentration of blocking solution, selection of the capture antibody pairs, and the sequences of triggering ssDNA and guiding RNA affected this immunoassay sensitivity. In contrast, the preincubation of CRISPR/Cas12a working solution and pre-mixture of detection antibody with anti-IgG-ssDNA did not show influence on the performance of CANi for the detection of insulin. Under optimized conditions, the sensitivity for detection of salivary insulin was 10 fg/ml with a linear range from 10 fg/ml to 1 ng/ml.

Potential of Point-of-Care and At-Home Assessment of Immune Status via Rapid Cytokine Detection and Questionnaire-Based Anamnesis

Monitoring the immune system's status has emerged as an urgent demand in critical health conditions. The circulating cytokine levels in the blood reflect a thorough insight into the immune system status. Indeed, measuring one cytokine may deliver more information equivalent to detecting multiple diseases at a time. However, if the reported cytokine levels are interpreted with considering lifestyle and any comorbid health conditions for the individual, this will promote a more precise assessment of the immune status. Therefore, this study addresses the most recent advanced assays that deliver rapid, accurate measuring of the cytokine levels in human blood, focusing on add-on potentials for point-of-care (PoC) or personal at-home usage, and investigates existing health questionnaires as supportive assessment tools that collect all necessary information for the concrete analysis of the measured cytokine levels. We introduced a ten-dimensional featuring of cytokine measurement assays. We found 15 rapid cytokine assays with assay time less than 1 h; some could operate on unprocessed blood samples, while others are mature commercial products available in the market. In addition, we retrieved several health questionnaires that addressed various health conditions such as chronic diseases and psychological issues. Then, we present a machine learning-based solution to determine what makes the immune system fit. To this end, we discuss how to employ topic modeling for deriving the definition of immune fitness automatically from literature. Finally, we propose a prototype model to assess the fitness of the immune system through leveraging the derived definition of the immune fitness, the cytokine measurements delivered by a rapid PoC immunoassay, and the complementary information collected by the health questionnaire about other health factors. In conclusion, we discovered various advanced rapid cytokine detection technologies that are promising candidates for point-of-care or at-home usage; if paired with a health status questionnaire, the assessment of the immune system status becomes solid and we demonstrated potentials for promoting the assessment tool with data mining techniques.

Point-of-Care Therapeutic Drug Monitoring for Precision Dosing of Immunosuppressive Drugs

BACKGROUND

Immunosuppressive drugs (ISD) are an essential tool in the treatment of transplant rejection and immune-mediated diseases. Therapeutic drug monitoring (TDM) for determination of ISD concentrations in biological samples is an important instrument for dose personalization for improving efficacy while reducing side effects. While currently ISD concentration measurements are performed at specialized, centralized facilities, making the process complex and laborious for the patient, various innovative technical solutions have recently been proposed for bringing TDM to the point-of-care (POC).

CONTENT

In this review, we evaluate current ISD-TDM and its value, limitations, and proposed implementations. Then, we discuss the potential of POC-TDM in the era of personalized medicine, and provide an updated review on the unmet needs and available technological solutions for the development of POC-TDM devices for ISD monitoring. Finally, we provide concrete suggestions for the generation of a meaningful and more patient-centric process for ISD monitoring.

SUMMARY

POC-based ISD monitoring may improve clinical care by reducing turnaround time, by enabling more frequent measurements in order to obtain meaningful pharmacokinetic data (i.e., area under the curve) faster reaction in case of problems and by increasing patient convenience and compliance. The analysis of the ISD-TDM field prompts the evolution of POC testing toward the development of fully integrated platforms able to support clinical decision-making. We identify 4 major areas requiring careful combined implementation: patient usability, data meaningfulness, clinicians' acceptance, and cost-effectiveness.

A point-of-care chemiluminescence immunoassay for pepsinogen I enables large-scale community health screening

Pepsinogen I (PGI) can reflect the morphology and function of the gastric mucosa. Accordingly, the large-scale community health screening of PGI can dramatically increase the early diagnosis rate of gastric cancer. However, PGI testing can only be carried out in comprehensive hospitals and health examination centers. To ameliorate this issue, a point-of-care chemiluminescent immunoassay for PGI was developed in a fully automated miniaturized instrument. This instrument was especially developed for health check-ups in the grassroots communities; its volume of which is only 0.18 m³. Critically, the entire detection process for a single sample only requires 20 min, and the samples can be loaded continuously, making the method suitable for high-throughput analysis. The assay displayed an excellent detection limit of 0.048 ng/mL with a broad detection range of 0-200 ng/mL. Furthermore, this assay exhibited high sensitivity and specificity, had low intra- and inter-assay coefficients of variation (<10%), and was not affected after storage at 37 °C for 7 days. The assay was used to detect PGI in 95 clinical serum samples, and the results were highly correlated with those that were clinically tested (correlation coefficient, R² = 0.998). Hence, the method established in this work has great application value and can be broadly applied for the large-scale screening of gastric cancer in resource-limited areas.

SARS-CoV-2 pandemic: a review of molecular diagnostic tools including sample collection and commercial response with associated advantages and limitations

The unprecedented global pandemic known as SARS-CoV-2 has exercised to its limits nearly all aspects of modern viral diagnostics. In doing so, it has illuminated both the advantages and limitations of current technologies. Tremendous effort has been put forth to expand our capacity to diagnose this deadly virus. In this work, we put forth key observations in the functionality of current methods for SARS-CoV-2 diagnostic testing. These methods include nucleic acid amplification-, CRISPR-, sequencing-, antigen-, and antibody-based detection methods. Additionally, we include analysis of equally critical aspects of COVID-19 diagnostics, including sample collection and preparation, testing models, and commercial response. We emphasize the integrated nature of assays, wherein issues in sample collection and preparation could impact the overall performance in a clinical setting.

Emerging biosensors in detection of natural products

Natural products (NPs) are a valuable source in the food, pharmaceutical, agricultural, environmental, and many other industrial sectors. Their beneficial properties along with their potential toxicities make the detection, determination or quantification of NPs essential for their application. The advanced instrumental methods require time-consuming sample preparation and analysis. In contrast, biosensors allow rapid detection of NPs, especially in complex media, and are the preferred choice of detection when speed and high throughput are intended. Here, we review diverse biosensors reported for the detection of NPs. The emerging approaches for improving the efficiency of biosensors, such as microfluidics, nanotechnology, and magnetic beads, are also discussed. The simultaneous use of two detection techniques is suggested as a robust strategy for precise detection of a specific NP with structural complexity in complicated matrices. The parallel detection of a variety of NPs structures or biological activities in a mixture of extract in a single detection phase is among the anticipated future advancements in this field which can be achieved using multisystem biosensors applying multiple flow cells, sensing elements, and detection mechanisms on miniaturized folded chips.

Point-of-care-ready nanoscale ISFET arrays for sub-picomolar detection of cytokines in cell cultures

Rapid and frequent screening of cytokines as immunomodulation agents is necessary for precise interventions in severe pathophysiological conditions. In addition to high-sensitivity detection of such analytes in complex biological fluids such as blood, saliva, and cell culture medium samples, it is also crucial to work out miniaturized bioanalytical platforms with potential for high-density integration enabling screening of multiple analytes. In this work, we show a compact, point-of-care-ready bioanalytical platform for screening of cytokines such as interleukin-4 (IL-4) and interleukin-2 (IL-2) based on one-dimensional ion-sensitive field-effect transistors arrays (nanoISFETs) of silicon fabricated at wafer-scale via nanoimprint lithography. The nanoISFETs biofunctionalized with receptor proteins alpha IL-4 and alpha IL-2 were deployed for screening cytokine secretion in mouse T helper cell differentiation culture media, respectively. Our nanoISFETs showed robust sensor signals for specific molecular binding and can be readily deployed for real-time screening of cytokines. Quantitative analyses of the nanoISFET-based bioanalytical platform was carried out for IL-4 concentrations ranging from 25 fg/mL (1.92 fM) to 2.5 μg/mL (192 nM), showing a limit of detection down to 3-5 fM, which was found to be in agreement with ELISA results in determining IL-4 concentrations directly in complex cell culture media. Graphical abstract.