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Loop-mediated isothermal amplification (LAMP) as a diagnostic tool is rapidly gaining recognition and maturity. Among various advantages over traditional polymerase chain reaction, the ability to visually detect amplification by the incorporation of colorimetric indicators is one of its most unique features. There is an overwhelming variety of LAMP indicators in the literature, yet a comprehensive comparative study is lacking. This study evaluates the use of hydroxynaphthol blue, phenol red, calcein, leuco crystal violet, malachite green, and a fluorescent dye for visual detection. A method for objective quantitative analysis using ImageJ is described that is readily implemented in standard and microfluidic workflows. The work here also includes the largest inter-reader variability study involving 24 participants to evaluate these indicators. We found inaccuracies in visual assessment as bias and/or individual-based perception can exist, solidifying the need for objective analysis. There was not a “universal” indicator, although considerations in sample preparation, storage, and applicability are discussed in length.

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Body fluids are a category of biological evidence that provides critical contextual clues for forensic investigations; blood, saliva, and semen are three of the most prevalently tested fluids in a forensic laboratory. Some of the existing colorimetric presumptive forensic assays for these fluids include: the phenolphthalein test or luminol test for blood, the acid phosphatase (AP) test or prostate-specific antigen (PSA) lateral flow assay for seminal fluid, and the alpha-amylase test for saliva. Even though these enzymatic-and immunological-based tests are widely utilized in the forensic workflow, they often lack sensitivity and specificity required for a confirmatory assay [1,2]. For example, a study by

An automated alignment method was optimized for maximizing laser-induced fluorescence detection in a total DNA analysis system, using innate opto-signatures from microchannel features.

The beginning of the COVID-19 pandemic demonstrated how few point-of-care diagnostic tools were available that could be safely and easily operated by healthcare workers with no laboratory training. The gold-standard test, and initially the only test, used RT-PCR with nasal pharyngeal swabs (NPS). Two issues quickly emerged: 1) RT-PCR required central laboratory processing leading to significant time delays and 2) NPS collection causes discomfort, is inappropriate for ongoing repeat sampling of individuals (e.g., frontline healthcare workers) and poses difficulty when obtaining samples from some sections of the population (e.g. some elderly and young children). The Sal6830 platform is a fully self-contained, RT-PCR point-of-care device for detecting SARS-CoV-2 from saliva that takes less than thirty minutes to complete. In this study we tested the usability of the Sal6830 platform by healthcare workers unfamiliar with the instrument at two community clinics: Care 4 U Community Health Center (Miami, Florida, USA) and St. Marys Health Wagon (Wise, Virginia, USA). Staff participated in three tests: 1) determining SARS-CoV-2 status from blinded positive and negative saliva samples, 2) a clinical study comparing SARS-CoV-2 detection with a comparator point-of-care technology from the same patient and 3) completing a survey designed to measure comfort and confidence using the Sal6830 point-of-care device having received no training. Participants overwhelming found the Sal6830 platform easy and intuitive to use, successfully called SARS-CoV-2 status of contrived, blinded samples and measured a 93.3% overall percent agreement when comparing patient samples across two point-of-care technologies.

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