Display of Potassium Channel–Blocking Tertiapin‐Q Peptides on Gold Nanoparticles Enhances Depolarization of Cellular Membrane Potential

Abstract

The use of nanoparticle (NP) systems to control cellular physiology, including membrane potential, can facilitate furthered understanding of many disparate cellular processes ranging from cellular proliferation to tissue regeneration. A gold NP (AuNP) bioconjugate system based on the honeybee venom peptide, tertiapin‐Q (AuNP‐TPN‐Q), that depolarizes membrane potential by targeting inward rectifier potassium channels (Kir), is developed. The conjugate elicits, in a peptide concentration–dependent manner, a greater and more rapid depolarization response compared to the free peptide alone. The specificity of the interaction of the AuNP‐TPN‐Q conjugate with the Kir channel using immunocytochemistry and competition binding assays is confirmed. It is further shown that membrane depolarization is photothermally reversible via the laser‐induced plasmonic heating of the AuNP, providing a level of control over Kir channels not afforded by currently available drugs. The functional nanobioconjugate described herein provides a new research tool for understanding the intricacies of ion channel activity and the modulation of cellular membrane potential.

Nanoparticle-Mediated Visualization and Control of Cellular Membrane Potential: Strategies, Progress, and Remaining Issues

“…Our laboratory performed initial modeling to examine the interaction of the peptide, tertiapin-Q (TPN-Q), with the Kir1.1 inward-rectifying K + channel when the peptide was displayed on the surface of a 10 nm core AuNP (Figure 10c). 29 This analysis showed that covalent attachment of TPN-Q to the AuNP surface allowed the peptide to interact freely with the channel. In PC-12 (rat phechromocytoma) cells differentiated with nerve growth factor to express Kir1.1 channels, the TPN-Q peptideconjugated AuNPs elicited a larger and more rapid depolarization response compared to the free peptide.…”

“…(iv) Depolarization with AuNP-TPN-Q bioconjugates (closed circle) but not with free peptide (open circle) is reversible by plasmonic heating. Adapted with permission from ref . Copyright 2019 Wiley-VCH.…”

“…Still other mechanical strategies have targeted ion channels by appending channel-specific peptides to the NP surface to augment peptide activity. Our laboratory performed initial modeling to examine the interaction of the peptide, tertiapin-Q (TPN-Q), with the Kir1.1 inward-rectifying K + channel when the peptide was displayed on the surface of a 10 nm core AuNP (Figure c) . This analysis showed that covalent attachment of TPN-Q to the AuNP surface allowed the peptide to interact freely with the channel.…”

Colloidal Capsules Assembled from Gold Nanoparticles Using Small-Molecule Hydrophobic Cross-linkers

“…Not surprisingly, per unit of gold, BTDP AuNCs (20 nm) did not heat as dramatically as gold nanorods (AuNR) which are well established as a preferred material for PTT . However, the ability to heat more mildly may have utility in applications such as depolarization of cell membrane potentials . Besides the application of PTT, one original motivation was to make enzymatically cleavable aggregates that could dissociate in vivo such that the initial size would lead to tumor targeting but the degradable nature would lead to enhanced liver clearance.…”

“…25 However, the ability to heat more mildly may have utility in applications such as depolarization of cell membrane potentials. 26 Besides the application of PTT, one original motivation was to make enzymatically cleavable aggregates that could dissociate in vivo such that the initial size would lead to tumor targeting but the degradable nature would lead to enhanced liver clearance. However, prior to this work, reports by Chan 27 and Tsourkas 28 lab demonstrated that once aggregates composed of 5 nm AuNPs are accumulated in the liver, they are actually cleared quite slowly.…”