Near-Infrared-Propelled Liquid Metal Boosting DNA Nanobullet for Triple-Mode Detection of Insulin-Like Growth Factor-1

Three-dimensional DNA nanomachine is an attractive tool in bioanalytical applications; however, the walking efficiency is still constrained by the inherent weak driving force. Herein, by utilizing the localized polymerization reaction of polyacrylamide (pAM) and DNA initiated on gallium-based liquid metal (LM), a near-infrared propelled LM-pAM-DNA nanobullet was designed to construct a colorimetric (CL), photothermal (PT), and electrochemical (EC) triple-mode sensing platform. The LM-pAM-DNA nanobullet held a good photothermal effect under near-infrared irradiation, which caused a temperature gradient between the nanobullet and the ambient solution to propel thermoelectrophoresis, resulting in a higher walking efficiency and shortened moving time. With the target-triggered walking process progressing, the DNA tracks on magnetic beads@mesoporous silica (MBs@SiO₂) conjugates were cleaved, leading to the release of loaded tetramethylbenzidine (TMB). Taking full advantage of the supernatant and precipitate, a triple-mode biosensing platform was constructed with the readout of colorimetric signal (CL mode) and photothermal signal (PT mode) of oxTMB, and electrochemical signal of the remnant TMB in MBs@SiO₂-DNA conjugates (EC mode). Using insulin-like growth factor-1 (IGF-1) as a model target, the proposed strategy achieved sensitive detection of IGF-1 with the detection limits of 83.73 pM, 447.73 pM, and 0.22 fM for CL, PT, and EC modes, respectively, providing a promising approach for early diagnosis and monitoring of disease.