AirJump: Using Interfaces to Instantly Perform Simultaneous Extractions.

Analyte isolation is an important process that spans a range of biomedical disciplines, including diagnostics, research, and forensics. While downstream analytical techniques have advanced in terms of both capability and throughput, analyte isolation technology has lagged behind, increasingly becoming the bottleneck in these processes. Thus, there exists a need for simple, fast, and easy to integrate analyte separation protocols to alleviate this bottleneck. Recently, a new class of technologies has emerged that leverages the movement of paramagnetic particle (PMP)-bound analytes through phase barriers to achieve a high efficiency separation in a single or a few steps. Specifically, the passage of a PMP/analyte aggregate through a phase interface (aqueous/air in this case) acts to efficiently "exclude" unbound (contaminant) material from PMP-bound analytes with higher efficiency than traditional washing-based solid-phase extraction (SPE) protocols (i.e., bind, wash several times, elute). Here, we describe for the first time a new type of "exclusion-based" sample preparation, which we term "AirJump". Upon realizing that much of the contaminant carryover stems from interactions with the sample vessel surface (e.g., pipetting residue, wetting), we aim to eliminate the influence of that factor. Thus, AirJump isolates PMP-bound analyte by "jumping" analyte directly out of a free liquid/air interface. Through careful characterization, we have demonstrated the validity of AirJump isolation through comparison to traditional washing-based isolations. Additionally, we have confirmed the suitability of AirJump in three important independent biological isolations, including protein immunoprecipitation, viral RNA isolation, and cell culture gene expression analysis. Taken together, these data sets demonstrate that AirJump performs efficiently, with high analyte yield, high purity, no cross contamination, rapid time-to-isolation, and excellent reproducibility.

HIV viral RNA extraction in wax immiscible filtration assisted by surface tension (IFAST) devices.

The monitoring of viral load is critical for proper management of antiretroviral therapy for HIV-positive patients. Unfortunately, in the developing world, significant economic and geographical barriers exist, limiting access to this test. The complexity of current viral load assays makes them expensive and their access limited to advanced facilities. We attempted to address these limitations by replacing conventional RNA extraction, one of the essential processes in viral load quantitation, with a simplified technique known as immiscible filtration assisted by surface tension (IFAST). Furthermore, these devices were produced via the embossing of wax, enabling local populations to produce and dispose of their own devices with minimal training or infrastructure, potentially reducing the total assay cost. In addition, IFAST can be used to reduce cold chain dependence during transportation. Viral RNA extracted from raw samples stored at 37°C for 1 week exhibited nearly complete degradation. However, IFAST-purified RNA could be stored at 37°C for 1 week without significant loss. These data suggest that RNA isolated at the point of care (eg, in a rural clinic) via IFAST could be shipped to a central laboratory for quantitative RT-PCR without a cold chain. Using this technology, we have demonstrated accurate and repeatable measurements of viral load on samples with as low as 50 copies per milliliter of sample.