DNA-Functionalized Silver Nanoparticles in an Alcoholic Solvent for Environment-Dictated Multimodal Actuation

Plasmonic nanoactuators with adaptability to uncontrolled environments resemble living systems and have implications in human-centered robotic applications, including nanomachinery, sensors, and drug delivery. Realization of the challenge has necessitated smart-ligand functionalization of plasmonic nanoparticles for the fine control of their arrangement under varied stimuli. Here we show that double-stranded DNA-functionalized silver nanoparticles (dsDNA-AgNPs) bearing poly(acrylic acid) (PAA) as the passivating ligand can store elastic energy releasable through a stimulus of heat, light, or pH. Heating or light excitation to blunt end-stacking-induced assemblies of dsDNA-AgNPs causes terminal opening of the dsDNA and entropic repulsion to overcome the attraction force, repristinating individual dsDNA-AgNPs. Furthermore, a pH change results in charge association/dissociation of the carboxyl groups in PAA, setting up an electrostatic force switch for the controlled actuation of dsDNA-AgNPs. Toward adaptable environmental actuation, we furnish dsDNA-AgNPs with the ability to adjust the actuation in response to changing temperature or light irradiation, based on alcohol-modulated terminal base pairing of the dsDNA. The study represents an important step toward fully environment-activatable, self-sustained intelligent nanosystems.