DNA-Functionalized Monolithic Hydrogels and Gold Nanoparticles for Colorimetric DNA Detection

Highly sensitive and selective DNA detection plays a central role in many fields of research and various assay platforms have been developed. Compared to homogeneous DNA detection, surface-immobilized probes allow washing steps and signal amplification to give higher sensitivity. Previously research was focused on developing glass or gold-based surfaces for DNA immobilization we herein report hydrogel-immobilized DNA. Specifically acrydite modified DNA was covalently functionalized to the polyacrylamide hydrogel during gel formation. There are several advantages of these DNA-functionalized monolithic hydrogels. First they can be easily handled in a way similar to that in homogeneous assays. Second they have a low optical background where in combination with DNA-functionalized gold nanoparticles even similar to 0.1 nM target DNA can be visually detected. By using the attached simple thermal treatment and the regenerated gels perform similarly to freshly prepared ones. The amount of gold nanoparticles adsorbed through DNA hybridization decreases with increasing gel percentage. Other parameters including the DNA concentration DNA sequence ionic strength of the solution and temperature have also been systematically characterized in this study.