Entropy-Driven DNA Amplification Networks Coupled with Hollow Porous Au–Ag Nanospheres for Split-Type Plasmonic Photothermal Biosensing

A bottom-up programmable and addressable DNA nanostructure is an ideal material for building reasonable and ingenious entropy-driven DNA amplification networks. Herein, superparamagnetic nanostructure-aided entropy-driven DNA amplification networks coupled with photostable Au–Ag hollow porous nanospheres (Au–Ag HPNS) have been applied to developing a flexible and elegant plasmonic photothermal biosensing platform. As a target model, when progesterone is captured by an aptamer in an initiator, the liberated target analogue can trigger the entropy-driven DNA amplification system via a toehold-mediated DNA strand replacement reaction, leading to the formation of Au–Ag HPNS/Fe3O4@SiO2 composites. While in the absence of the target, only biofunctional Fe3O4@SiO2 nanoparticles are extracted. The more the targets, the higher the temperature increment. Entropy-driven DNA amplification networks with double-stranded assembly structures rather than DNA hairpins enable greatly improved programmability. Also, the base pairs in entropy-driven DNA amplification networks remain constant, efficiently avoiding the interferences from members of their family and other complex matrices, leading to robust thermal stability. In addition to the entropy-driven DNA amplifier, superparamagnetic Fe3O4@SiO2 nanoparticles offer a synergistic effect to enhance detection sensitivity by enriching the temperature report module. Particularly, this unparalleled split-type design endows the photothermal biosensor with a strong anti-interference feature. In addition to these advantages, the as-designed plasmonic photothermal biosensor was successfully utilized to monitor progesterone in practical settings, with high performance in terms of cost-effectiveness, portability, high-speed acquisition, and easy operation and maintenance.