Solar-thermal complex sample processing for nucleic acid based diagnostics in limited resource settings

Abstract

The use of point-of-care (POC) devices in limited resource settings where access to commonly used infrastructure, such as water and electricity, can be restricted represents simultaneously one of the best application fits for POC systems as well as one of the most challenging places to deploy them. Of the many challenges involved in these systems, the preparation and processing of complex samples like stool, vomit, and biopsies are particularly difficult due to the high number and varied nature of mechanical and chemical interferents present in the sample. Previously we have demonstrated the ability to use solar-thermal energy to perform PCR based nucleic acid amplifications. In this work demonstrate how the technique, using similar infrastructure, can also be used to perform solar-thermal based sample processing system for extracting and isolating Vibrio Cholerae nucleic acids from fecal samples. The use of opto-thermal energy enables the use of sunlight to drive thermal lysing reactions in large volumes without the need for external electrical power. Using the system demonstrate the ability to reach a 95°C threshold in less than 5 minutes and maintain a stable sample temperature of +/− 2°C following the ramp up. The system is demonstrated to provide linear results between 104 and 108 CFU/mL when the released nucleic acids were quantified via traditional means. Additionally, we couple the sample processing unit with our previously demonstrated solar-thermal PCR and tablet based detection system to demonstrate very low power sample-in-answer-out detection.

On-chip stool liquefaction via acoustofluidics

“…Additionally, the need for cross-instrumentation operation may lead to severe biohazard risks and operator-dependence can compound detection results. 11 Therefore, the development of rapid, reliable, and automated point-of-care (POC) devices for stool processing and analysis is critical for reducing biosafety concerns and improving diagnoses and healthcare.…”

Sample Preparation for Lab-on-a-Chip Systems in Molecular Diagnosis: A Review

“…80 In 2016, Gumus et al also employed this method to purify fecal samples and isolate Vibrio cholerae nucleic acids. 81 The group developed a solar-thermal sample processing system to achieve a 95 °C pyrolysis temperature in less than 5 min through a black polycarbonate solar incubator. The samples were kept at that temperature for 10 min.…”

“…The beads were removed with a magnet, and the DNA was transferred to a clean tube for the PCR amplification reactions using a solar thermal system. 81 A summary of these methodologies is given in Table 5.…”

“…The magnetic beads were washed with a buffer, and then elution buffer was added, mixed and incubated at 60 °C for 5 min using a solar incubator. The beads were removed with a magnet, and the DNA was transferred to a clean tube for the PCR amplification reactions using a solar thermal system . A summary of these methodologies is given in Table .…”

The Many Roads to an Ideal Paper-based Device

“…More recently, extraction and isolation of Vibrio cholerae from fecal samples were performed using solar-thermal energy. Here, without the need of external electrical power, a stable temperature of 95 • C was achieved in less than 5 min [56].…”