# Just a little prick: careful cell contacts enabled by ceramic nanostraws

## TL;DR

Nanostraw arrays can deliver substances into immune cells without damaging them, even under stressful conditions.

## Contribution

Nanostraw arrays enable intracellular contact and substance delivery in macrophage-like cells without activation or damage.

## Key findings

- THP-1 cells remain healthy and unactivated on nanostraw arrays.
- Gold nanoparticles and fluorescence-labeled antibodies were successfully delivered into THP-1 cells.
- Nanostraw arrays could be used for measuring membrane potential under hypoxia.

## Abstract

Nanostraw arrays represent a novel and promising approach for the controlled delivery of substances into cells characterized by very little cellular activation or damage. Herein, we describe a sensitive strategy to establish intracellular contact with human macrophage-like differentiated THP-1 cells. Macrophages must function under stressful in-vivo conditions in oxygen-deprived tissues with inflammation. THP-1 cells stayed healthy and did not show signs of activation when cultured on nanostraw arrays. Importantly, we found convincing evidence for the successful delivery of gold nanoparticles and fluorescence-labeled antibodies into THP-1 cells. Future applications of nanostraw arrays are the functionalization with silane coating to immobilize proteins and/or the analysis of membrane located ion channels in THP-1 cells by electrophysiology. Our findings demonstrate that nanostraw arrays can enable intracellular contact for substance delivery and they might also allow measurements of the cellular membrane potential under stressful culture conditions like hypoxia in the future, in particular for immune cells.

The online version contains supplementary material available at 10.1007/s00424-026-03150-7.