A portable colorimetric point-of-care testing platform for MicroRNA detection based on programmable entropy-driven dynamic DNA network modulated DNA-gold nanoparticle hybrid hydrogel film

Point-of-care testing (POCT) platforms for microRNA (miRNA) detection have attracted considerable attention in recent years, due to the increasingly important role of miRNA as biomarkers for the diagnosis of many diseases, such as cancers. However, several limitations such as the requirement of enzyme-related amplification system, expensive preservation cost, sophisticated analysis instruments and tedious operations of conventional miRNA biosensing devices severely hinder their widespread applications. In this work, a portable and smart colorimetric analysis platform was developed by employing the ultrathin DNA-gold nanoparticle (AuNP) hybrid hydrogel film as the signaling unit and the enzyme-free entropy-driven dynamic DNA network (EDN) as the signal converter and amplification unit. By programming the DNA sequences of the EDN, the EDN could respond to a specific miRNA, with miRNA-155 or miRNA-21 as the model target, and release a converter DNA with amplified con-centration to further trigger the release of AuNPs from the hydrogel film as a colorimetric signal output. To avoid the use of sophisticated spectral instruments, digital analysis based on primary three-color channel (R/G/B) was further introduced by using user-friendly camera and image processing software, and a detection limit at pM level was achieved. Moreover, by introducing H2O2-mediated AuNPs enlargement procedure in the colorimetric analysis platform, the detection limit for miRNA target could further be enhanced to fM level. The POCT platform is also portable and storable with a good storage stability for at least 45 days, suggesting its great potential in practical diagnosis applications.

Automated summary

To overcome the limitations of conventional miRNA biosensing devices, researchers have developed a portable and smart colorimetric analysis platform using DNA-gold nanoparticles and an enzyme-free dynamic DNA network. By programming the DNA sequences, the dynamic DNA network can respond to specific miRNA and trigger the release of gold nanoparticles from the hydrogel film as a colorimetric signal output. Digital analysis based on primary three-color channel was introduced to achieve a detection limit at pM level. Furthermore, by introducing a H2O2-mediated gold nanoparticles enlargement procedure, the detection limit for miRNA target could be further enhanced to fM level. The portable and storable platform exhibits good storage stability for at least 45 days, showing great potential in practical diagnosis applications.