Microfluidic diagnostic technologies for global public health

The developing world does not have access to many of the best medical diagnostic technologies; they were designed for air-conditioned laboratories, refrigerated storage of chemicals, a constant supply of calibrators and reagents, stable electrical power, highly trained personnel and rapid transportation of samples. Microfluidic systems allow miniaturization and integration of complex functions, which could move sophisticated diagnostic tools out of the developed-world laboratory. These systems must be inexpensive, but also accurate, reliable, rugged and well suited to the medical and social contexts of the developing world.     

Molecular diagnostics in a teacup: Non-Instrumented Nucleic Acid Amplification (NINA) for rapid, low cost detection of Salmonella enterica

We report on the use of a novel non-instrumented platform to enable a Loop Mediated isothermal Amplification(LAMP) based assay for Salmonella enterica.Heat energy is provided by addition of a small amount(<150 g) of boiling water,and the reaction temperature is regulated by storing latent energy at the melting temperature of a lipid-based engineered phase change material.Endpoint classification of the reaction is achieved without opening the reaction tube by observing the fluorescence of sequence-specific FRET-based assimilating probes with a simple handheld fluorometer.At or above 22℃ ambient temperature the non-instrumented devices could maintain reactions above a threshold temperature of 61℃ for over 90 min-significantly longer than the 60 min reaction time.Using the simple format,detection limits were less than 20 genome copies for reactions run at ambient temperatures ranging from 8 to 36℃.When used with a pre-enrichment step and non-instrumented DNA extraction device,trace contaminations of Salmonella in milk close to 1 CFU/mL could be reliably detected.These findings illustrate that the non-instrumented amplification approach is a simple,viable,low-cost alternative for field-based food and agricultural diagnostics or clinical applications in developing countries.