A Paper-Based IL-6 Test Strip Coupled With a Spectrum-Based Optical Reader for Differentiating Influenza Severity in Children

Influenza virus infection is a major worldwide public health problem. Influenza virus infections are associated with a high hospitalization rate in children between the ages of 5 and 14. The predominant reason for poor influenza prognosis is the lack of any effective means for early diagnosis. Early diagnosis of severe illness is critical to improving patient outcome, and could be especially useful in areas with limited medical resources. Accurate, inexpensive, and easy-to-use diagnostic tools could improve early diagnosis and patient outcome, and reduce overall healthcare costs. We developed an interleukin-6 paper-based test strip that used colloidal gold-conjugated antibodies to detect human interleukin-6 protein. These complexes were captured on a paper-based test strip patterned with perpendicular T lines that were pre-coated with anti-human interleukin-6 antibodies. Applied serum samples interacted with these antibodies and presented as colored bands that could be read using a spectrum-based optical reader. The full-spectrum of the reflected light interleukin-6 protein signal could be obtained from the spectral optics module, and the standard could be used to quantitatively analyze interleukin 6 level in serum. We retrospectively evaluated 10 children (23 serum samples) with severe influenza virus infections, 26 children (26 serum samples) with mild influenza virus infections, and 10 healthy children (10 serum samples). Our system, the combined use of a paper-based test strip and a spectrum-based optical reader, provided both qualitative and quantitative information. When used with the optical reader, the detection limit was improved from a qualitative, naked-eye level of 400 pg/ml to a quantitative, optical reader level of 76.85 pg/ml. After monitoring serum interleukin-6 level via our system, we found a high correlation between our system results and those obtainable using a conventional sandwich enzyme-linked immunosorbent assay method (Rho = 0.706, p < 0.001). The sensitivity and specificity for differentiating between severe and mild influenza using our combined method (test strip coupled with optical reader) were 78.3 and 50.0%, respectively. When interleukin-6 was combined with serum C-reaction protein, the sensitivity and specificity were 85.7 and 95.5%, and the receiver operating characteristic area-under-the-curve was quite high (AUC = 0.911, p < 0.001). The potential advantages of our system, i.e., a paper-based test strip coupled with a spectrum-based optical reader, are as follows: 1) simple user operation; 2) rapid turnaround times–within 20 min; 3) high detection performance; and, 4) low-cost fabrication.

Point-of-care semiquantitative test for adherence to tenofovir alafenamide or tenofovir disoproxil fumarate

Objective: Objective measurement of antiretrovirals may aid clinical interventions for improving adherence to HIV prevention or treatment regimens. A point-of-care urine test could provide real-time information about recent adherence to regimens containing tenofovir disoproxil fumarate (TDF) or tenofovir alafenamide (TAF). We developed a lateral flow immunoassay (LFA) and enzyme-linked immunoassay (ELISA) for urinary tenofovir. Methods: Intensity of the LFA test line was quantified using an optical reader and visually scored 0 - 5 by two independent people, using a reference card. The sensitivity and specificity of both the ELISA and LFA were determined for two different tenofovir concentration cutoffs for TDF and TAF adherence-1,500 ng/mL and 150 ng/mL, respectively. To validate the assays, we measured 586 urine samples from 28 individuals collected as part of a study of tenofovir pharmacokinetics in adults, which were also measured by mass spectrometry as ground truth. Results: Both the LFA signal and ELISA signal were each strongly correlated to drug concentrations (0.91 and 0.92 respectively). The LFA signal and ELISA were highly sensitive and specific at both thresholds (LFA se/sp TDF 89%/96%, TAF 90%/96%; ELISA se/sp TDF 94%/94%, TAF 92%/84%). Visual scoring of the LFA was also highly sensitive and specific at both the TDF and TAF thresholds (se/sp TDF 91%/94%, TAF 87%/90%). Conclusions: Our rapid semi-quantitative test can measure TFV concentrations relevant to both TAF or TDF adherence, which may support adherence-promoting interventions across a range of HIV care settings.

A SARS-CoV-2 Coronavirus Nucleocapsid Protein Antigen-Detecting Lateral Flow Assay

<p></p><p>Inexpensive, simple, rapid diagnostics are necessary for efficient detection, treatment and mitigation of COVID‑19. Currently, the primary diagnostic tool being utilized is reverse transcription polymerase chain reaction (RT-PCR). RT-PCR delivers results with good sensitivity and excellent specificity, but is expensive, prone to access challenges and is often slowed by transport to centralized testing laboratories. Antigen-based assays are inexpensive and can be rapidly mass-produced and deployed, with lateral flow assays (LFAs) being the most common inexpensive antigen test. To date, few antigen-detecting LFAs for COVID-19 have been commercialized. Herein, we present an open source LFA using commercially available antibodies and materials for the detection of SARS-CoV-2. Using an optical reader with comparable sensitivity to a visual read, the LFA yielded a Limit of Detection (LOD) of 23 TCID₅₀/mL (95% CI of 9.1 to 37 TCID₅₀/mL), equivalent to 1.4x10⁵ copies/mL (95% CI of 5.5x10⁴ to 2.3x10⁵ copies/mL) irradiated virus in pooled nasal matrix. This LOD meets the criteria suggested by WHO for diagnosis of acute SARS-CoV-2 infection in a point of care format. A clinical evaluation and further testing is ongoing.</p><p></p>

A SARS-CoV-2 Coronavirus Nucleocapsid Protein Antigen-Detecting Lateral Flow Assay

<p></p><p>Inexpensive, simple, rapid diagnostics are necessary for efficient detection, treatment and mitigation of COVID‑19. Currently, the primary diagnostic tool being utilized is reverse transcription polymerase chain reaction (RT-PCR). RT-PCR delivers results with good sensitivity and excellent specificity, but is expensive, prone to access challenges and is often slowed by transport to centralized testing laboratories. Antigen-based assays are inexpensive and can be rapidly mass-produced and deployed, with lateral flow assays (LFAs) being the most common inexpensive antigen test. To date, few antigen-detecting LFAs for COVID-19 have been commercialized. Herein, we present an open source LFA using commercially available antibodies and materials for the detection of SARS-CoV-2. Using an optical reader with comparable sensitivity to a visual read, the LFA yielded a Limit of Detection (LOD) of 23 TCID₅₀/mL (95% CI of 9.1 to 37 TCID₅₀/mL), equivalent to 1.4x10⁵ copies/mL (95% CI of 5.5x10⁴ to 2.3x10⁵ copies/mL) irradiated virus in pooled nasal matrix. This LOD meets the criteria suggested by WHO for diagnosis of acute SARS-CoV-2 infection in a point of care format. A clinical evaluation and further testing is ongoing.</p><p></p>

Design and Development of Point of Care Test and Optical Reader for Early Screening of Kidney Related Disorder

Low-cost, paper-based colorimetric assays for early screening of albumin, creatinine and their ratio have been developed. The developed methods are noninvasive and require only 10µl of the urine sample. A reflectance-based optical reader has also been developed for the quantification of the albumin and creatinine. The developed method is based on spot urine testing which is advantageous when compared to the conventional 24-hour urine collection. The detection range of albumin and creatinine assays is 10-150 mg/dl and 25–400 mg/dl, respectively. The developed assays and optical reader were tested with the chronic kidney diseased patient’s samples at KEM Hospital, Mumbai.

Real-time particle-by-particle detection of erythrocyte-camouflaged microsensor with extended circulation time in the bloodstream

Personalized medicine offers great potential benefits for disease management but requires continuous monitoring of drugs and drug targets. For instance, the therapeutic window for lithium therapy of bipolar disorder is very narrow, and more frequent monitoring of sodium levels could avoid toxicity. In this work, we developed and validated a platform for long-term, continuous monitoring of systemic analyte concentrations in vivo. First, we developed sodium microsensors that circulate directly in the bloodstream. We used “red blood cell mimicry” to achieve long sensor circulation times of up to 2 wk, while being stable, reversible, and sensitive to sodium over physiologically relevant concentration ranges. Second, we developed an external optical reader to detect and quantify the fluorescence activity of the sensors directly in circulation without having to draw blood samples and correlate the measurement with a phantom calibration curve to measure in vivo sodium. The reader design is inherently scalable to larger limbs, species, and potentially even humans. In combination, this platform represents a paradigm for in vivo drug monitoring that we anticipate will have many applications in the future.

A system for the control and recording of physical parameters inside a chamber for UV-C irradiating of biological material

This paper presents a system for the control and recording of physical parameters inside a chamber for UV-C irradiating of biological material. The system was based on the HOBO U23-002 temperature and humidity recorder equipped with an integrated external probe, BASE-U-4 optical reader for programming and reading data from HOBO U series recorders, LIGHT METER radiation meter UVC-254 model equipped with a photodiode probe (LP UV-C 01) with a sensitivity of 0.19 μW.cm-2 and sampling time 0.4 s, HOBOware Lite software (for archiving temperature and relative humidity measurement results) with a PC, RS-232 serial interface and dedicated software (SWU-801 LUTRON and SW-U101-WIN) enabling interaction with the meter (for archiving UV-C radiation measurements) and a PC. The operation of the system was tested in real operating conditions of the chamber, by irradiating potato tubers of Innovator variety at different settings of the UV-C radiator. The data obtained was analysed against the significance level assumed of α = 0.05. Significant influence of the qualitative predictors on the dependent variables examined was shown.