DNA-Based Sensor Particles Enable Measuring Light Intensity in Single Cells

Accelerated non-crosslinking assembly of DNA-functionalized nanoparticles in alcoholic solvents: for application in the identification of clear liquors

Colorimetric detection of various target molecules in aqueous solutions based on the non-crosslinking assembly of DNA-functionalized Au nanoparticles (DNA-AuNPs) has been well established in recent years. The extension of DNA-AuNPs to other solvents remains much less explored, despite the practical importance of detection in non-aqueous solutions, such as those containing an organic ingredient that is required or not removable in many contexts. However, the general consideration that DNA is easily denatured and precipitated in organic solvents has been hampering the use of DNA-AuNPs in low polar solvents. Herein, we report a more rapid non-crosslinking assembly of double-stranded (ds) DNA-AuNPs in alcoholic solvents than in aqueous solvents. When the concentration of ethanol in the disperse medium is increased from 0% to 20% (v/v), the rate of non-crosslinking assembly is distinctly increased by a factor of 5-6, whereas the rate is sharply decreased when the ethanol concentration is further increased to 40%. This biphasic kinetics trend could be attributed to the competitive balance between the enhanced intermolecular attraction between dsDNAs and the increased propensity for melting of dsDNA. Rapid naked-eye identification of clear liquors that are encoded by oligonucleotide additives has also been demonstrated by using the alcoholic non-crosslinking assembly of dsDNA-AuNPs as a proof-of-concept.

Tomographic Reservoir Imaging with DNA-Labeled Silica Nanotracers: The First Field Validation

This study presents the first field validation of using DNA-labeled silica nanoparticles as tracers to image subsurface reservoirs by travel time based tomography. During a field campaign in Switzerland, we performed short-pulse tracer tests under a forced hydraulic head gradient to conduct a multisource-multireceiver tracer test and tomographic inversion, determining the two-dimensional hydraulic conductivity field between two vertical wells. Together with three traditional solute dye tracers, we injected spherical silica nanotracers, encoded with synthetic DNA molecules, which are protected by a silica layer against damage due to chemicals, microorganisms, and enzymes. Temporal moment analyses of the recorded tracer concentration breakthrough curves (BTCs) indicate higher mass recovery, less mean residence time, and smaller dispersion of the DNA-labeled nanotracers, compared to solute dye tracers. Importantly, travel time based tomography, using nanotracer BTCs, yields a satisfactory hydraulic conductivity tomogram, validated by the dye tracer results and previous field investigations. These advantages of DNA-labeled nanotracers, in comparison to traditional solute dye tracers, make them well-suited for tomographic reservoir characterizations in fields such as hydrogeology, petroleum engineering, and geothermal energy, particularly with respect to resolving preferential flow paths or the heterogeneity of contact surfaces or by enabling source zone characterizations of dense nonaqueous phase liquids.