Growth of Gold Nanostars in Flow: A Platform for Antifouling and Small Molecule Sensing

Gold (Au) nanostructures are an ideal material for integration into devices for medical and biological applications due to their tunable and unique size-related properties and biocompatibility. In this work, we develop a rapid and scalable strategy for the seed-mediated growth of branched Au nanoparticles in situ utilizing microfluidics. The synthesized Au nanostars are characterized by strong plasmonic responses in the near infrared, and nanometer tip curvatures that enable efficient photon-to-heat conversion through plasmon-phonon coupling. This localized hyperthermia effect has been employed for the controlled “soft” detachment of adherent cells, which give our platform antifouling properties that can be applied towards the development of microfluidic devices for cell sorting, drug delivery, or transfection. Additionally, we target small molecule and drug sensing within biological samples via surface-enhanced Raman spectroscopy, due to the Au nanostars’ localized surface plasmon resonance in the biological window. In particular, we focus on applying this device for the detection of warfarin (anticoagulant) in the blood at biologically relevant concentrations.