ABSTRACT
The simple, rapid magnetic manipulation of paramagnetic particles (PMPs) paired with the wide range of available surface chemistries has strongly positioned PMPs in the field of analyte isolation. One recent technology, sliding lid for immobilized droplet extractions (SLIDE), presents a simple, rapid alternative to traditional PMP isolation protocols. Rather than remove fluid from PMP-bound analyte, SLIDE directly removes the PMPs from the fluid. SLIDE collects the PMPs on a hydrophobic, removable surface, which allows PMPs to be captured from one well and then transferred and released into a second well. Despite several key advantages, SLIDE remains limited by its passive magnetic manipulation that only allows for a one-time capture-and-release of PMPs, preventing wash steps and limiting purity. Furthermore, the strategy employed by SLIDE constrains the position of the wells, thereby limiting throughput and integration into automated systems. Here, we introduce a new, mechanically and operationally simplistic magnetic manipulation system for integration with the SLIDE technology to overcome the previously stated limitations. This magnetic system is compatible with nearly any plate design, can be integrated into automated workflows, enables high-throughput formats, simplifies mechanical requirements, and is amenable to a range of analytes. Using this magnetic system, PMPs can be collected, released, and resuspended throughout multiple wells regardless of proximity. We demonstrate this system's capabilities to isolate whole cells, mRNA, and DNA, demonstrating up to a 28-fold improvement of purity via the multiwash protocols enabled by this magnetic technology.
ABSTRACT
While potentially powerful, access to molecular diagnostics is substantially limited in the developing world. Here we present an approach to reduced cost molecular diagnostic instrumentation that has the potential to empower developing world communities by reducing costs through streamlining the sample preparation process. In addition, this instrument is capable of producing its own consumable devices on demand, reducing reliance on assay suppliers. Furthermore, this instrument is designed with an "open" architecture, allowing users to visually observe the assay process and make modifications as necessary (as opposed to traditional "black box" systems). This open environment enables integration of microfluidic fabrication and viral RNA purification onto an easy-to-use modular system via the use of interchangeable trays. Here we employ this system to develop a protocol to fabricate microfluidic devices and then use these devices to isolate viral RNA from serum for the measurement of human immunodeficiency virus (HIV) viral load. Results obtained from this method show significantly reduced error compared with similar nonautomated sample preparation processes.