Aashish Priye

Lab-on-a-Drone: Toward Pinpoint Deployment of Smartphone-Enabled Nucleic Acid-Based Diagnostics for Mobile Health Care

We introduce a portable biochemical analysis platform for rapid field deployment of nucleic acid-based diagnostics using consumer-class quadcopter drones. This approach exploits the ability to isothermally perform the polymerase chain reaction (PCR) with a single heater, enabling the system to be operated using standard 5 V USB sources that power mobile devices (via battery, solar, or hand crank action). Time-resolved fluorescence detection and quantification is achieved using a smartphone camera and integrated image analysis app. Standard sample preparation is enabled by leveraging the drones motors as centrifuges via 3D printed snap-on attachments. These advancements make it possible to build a complete DNA/RNA analysis system at a cost of ∼

Microscale Chaotic Advection Enables Robust Convective DNA Replication

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Computations of Lifshitz–van der Waals interaction energies between irregular particles and surfaces at all separations for resuspension modelling

US). Our instrument is rugged and versatile, enabling pinpoint deployment of sophisticated diagnostics to distributed field sites. This capability is demonstrated by successful in-flight replication of Staphylococcus aureus and λ-phage DNA targets in under 20 min. The ability to perform rapid in-flight assays with smartphone connectivity eliminates delays between sample collection and analysis so that test results can be delivered in minutes, suggesting new possibilities for drone-based systems to function in broader and more sophisticated roles beyond cargo transport and imaging.

Synchronized chaotic targeting and acceleration of surface chemistry in prebiotic hydrothermal microenvironments

The ability of chaotic advection under microscale confinement to direct chemical processes along accelerated kinetic pathways has been recognized for some time. However, practical applications have been slow to emerge because optimal results are often counterintuitively achieved in flows that appear to possess undesirably high disorder. Here we present a 3D time-resolved analysis of polymerase chain reaction (PCR)-mediated DNA replication across a broad ensemble of geometric states. The resulting parametric map reveals an unexpectedly wide operating regime where reaction rates remain constant over 2 orders of magnitude of the Rayleigh number, encompassing virtually any realistic PCR condition (temperature, volume, gravitational alignment), a level of robustness previously thought unattainable in the convective format.

Convective PCR Thermocycling with Smartphone-Based Detection: A Versatile Platform for Rapid, Inexpensive, and Robust Mobile Diagnostics

The phenomenon of particle resuspension plays a vital role in numerous fields. Among many aspects of particle resuspension dynamics, a dominant concern is the accurate description and formulation of the van der Waals (vdW) interactions between the particle and substrate. Current models treat adhesion by incorporating a material-dependent Hamakers constant which relies on the heuristic Hamakers two-body interactions. However, this assumption of pairwise summation of interaction energies can lead to significant errors in condensed matter as it does not take into account the many-body interaction and retardation effects. To address these issues, an approach based on Lifshitz continuum theory of vdW interactions has been developed to calculate the principal many-body interactions between arbitrary geometries at all separation distances to a high degree of accuracy through Lifshitzs theory. We have applied this numerical implementation to calculate the many-body vdW interactions between spherical particles and surfaces with sinusoidally varying roughness profile and also to non-spherical particles (cubes, cylinders, tetrahedron etc) orientated differently with respect to the surface. Our calculations revealed that increasing the surface roughness amplitude decreases the adhesion force and non-spherical particles adhere to the surfaces more strongly when their flatter sides are oriented towards the surface. Such practical shapes and structures of particle–surface systems have not been previously considered in resuspension models and this rigorous treatment of vdW interactions provides more realistic adhesion forces between the particle and the surface which can then be coupled with computational fluid dynamics models to improve the predictive capabilities of particle resuspension dynamics.

Micro-Scale Transport Processes for Advanced Healthcare and Point of Care Diagnostics

Significance We describe a physical mechanism capable of achieving simultaneous mixing and focused enrichment in hydrothermal pore microenvironments. Microscale chaotic advection established in response to a temperature gradient paradoxically promotes bulk homogenization of molecular species, while at the same time transporting species to discrete targeted locations on the bounding sidewalls where they become highly enriched. This process delivers an order of magnitude acceleration in surface reaction kinetics under conditions naturally found in subsea hydrothermal microenvironments, suggesting a new avenue to explain prebiotic emergence of macromolecules from dilute organic precursors—a key unanswered question in the origin of life on Earth and elsewhere. Porous mineral formations near subsea alkaline hydrothermal vents embed microenvironments that make them potential hot spots for prebiotic biochemistry. But, synthesis of long-chain macromolecules needed to support higher-order functions in living systems (e.g., polypeptides, proteins, and nucleic acids) cannot occur without enrichment of chemical precursors before initiating polymerization, and identifying a suitable mechanism has become a key unanswered question in the origin of life. Here, we apply simulations and in situ experiments to show how 3D chaotic thermal convection—flows that naturally permeate hydrothermal pore networks—supplies a robust mechanism for focused accumulation at discrete targeted surface sites. This interfacial enrichment is synchronized with bulk homogenization of chemical species, yielding two distinct processes that are seemingly opposed yet synergistically combine to accelerate surface reaction kinetics by several orders of magnitude. Our results suggest that chaotic thermal convection may play a previously unappreciated role in mediating surface-catalyzed synthesis in the prebiotic milieu.

Smartphone-Enabled Detection Strategies for Portable PCR–Based Diagnostics

Development of portable PCR-based diagnostic instruments has potential to greatly expand availability of advanced health care technologies. But issues associated with cost, complexity, electrical power requirements, and product detection continue to make PCR challenging to deploy outside of conventional laboratory environments. Here we review exciting recent progress toward development of convective thermocycling approaches that promise to overcome these limitations, laying a foundation for a new generation of inexpensive and greatly simplified diagnostic tools that can be readily deployed in a host of field-based settings.

Education: DNA replication using microscale natural convection

Recent outbreaks like Zika and Ebola highlights the challenges associated with pathogen diagnostics in the developing world. With the outbreak in Africa, and isolated cases on other continents, the need for an affordable, rapid and portable diagnostic solution has been repeatedly stressed and is one of the most critical issues confronting global health. Unfortunately, the current conventional PCR instrumentation needed to perform gold standard DNA-based diagnostic tests is bulky, slow, and expensive, making it unsuitable for resource-limited settings in developing countries where dedicated laboratory facilities are not available. Advances in micro-fluidics and smartphone based technology has paved way for novel implementations of traditional molecular diagnostic techniques. We present a series of advances in molecular diagnostic techniques by harnessing convective flow to actuate biochemical reactions.

DNA-to-go: A portable smartphone-enabled PCR assay platform

Incredible progress continues to be made toward development of low-cost nucleic acid-based diagnostic solutions suitable for deployment in resource-limited settings. Detection components play a vitally important role in these systems, but have proven challenging to adapt for operation in a portable format. Here we describe efforts aimed at leveraging the capabilities of consumer-class smartphones as a convenient platform to enable detection of nucleic acid products associated with DNA amplification via the polymerase chain reaction (PCR). First, we show how fluorescence-based detection can be incorporated into a portable convective thermocycling system controlled by a smartphone app. Raw images captured by the phones camera are processed to yield real-time amplification data comparable to benchtop instruments. Next, we leverage smartphone imaging to achieve label-free detection of PCR products by monitoring changes in electrochemical reactivity of embedded metal electrodes as the target DNA concentration increases during replication. These advancements make it possible to construct rugged inexpensive nucleic acid detection components that can be readily embedded in a variety of portable bioanalysis instruments.