Photothermal-Enhanced Modulation of Cellular Membrane Potential Using Long-Wavelength-Activated Gold Nanoflowers

Abstract

In mammalian cells, plasma membrane potential plays vital roles in both physiology and pathology and it is controlled by a network of membrane-resident ion channels. There is considerable interest in the use of nanoparticles (NPs) to control biological functions, including the modulation of membrane potential. The photoexcitation of gold NPs (AuNPs) tethered close to the plasma membrane has been shown to induce membrane depolarization via localized heating of the AuNP surface coupled with the opening of voltage-gated sodium channels. Previous work has employed spherical AuNPs (AuNS) with absorption in the 500–600 nm range for this purpose. However, AuNP materials with absorption at longer wavelengths [e.g., near-infrared (NIR)] would enable greater tissue penetration depth in vivo. We show here the use of new anisotropic-shaped AuNPs [gold nanoflowers (AuNFs)] with broad absorption spanning into the NIR part of the spectrum (∼650–1000 nm). The AuNFs are directly synthesized with bidentate thiolate ligands, which preserves the AuNF’s shape and colloidal stability, while facilitating conjugation to biomolecules. We describe the characterization of the AuNF particles and demonstrate that they adhere to the plasma membrane when bioconjugated to PEGylated cholesterol (PEG-Chol) moieties. The AuNF-PEG-Chol mediated the depolarization of rat adrenal medulla pheochromocytoma (PC-12) neuron-like cells more effectively than AuNS-PEG-Chol and unconjugated AuNS and AuNF when photoexcited at ∼561 or ∼640 nm. Importantly, AuNF induction of depolarization had no impact on cellular viability. This work demonstrates anisotropic AuNFs as an enabling nanomaterial for use in cellular depolarization and the spatiotemporal control of cellular activity.

A Laser‐Driven Microrobot for Thermal Stimulation of Single Cells

“…[18][19][20][21] Specifically, plasmonic gold nanomaterials have been used to investigate the dynamic influence of temperature on integrin signaling, heat shock protein formation, apoptosis, and activation of voltage-gated ion channels at the single cell level. [17,[22][23][24][25] Despite their remarkable performance, plasmonic small-scale heaters alone are incapable of providing 3D cell culture conditions relevant to native tissue, which is now widely accepted as a crucial requirement for cell culture. Integrating plasmonic nanodevices in cell life supporting biomaterials was recently proposed as an alternative, which demonstrated that gold nanorods retain their photothermal actuation capabilities when embedded in 3D hydrogel scaffolds.…”