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.