Nanostars on Nanopipette Tips: A Raman Probe for Quantifying Oxygen Levels in Hypoxic Single Cells and Tumours

Abstract

Multiple sharp‐edged gold nanostars were efficiently assembled on nanopipette tips through electrostatic interactions for use as a potent intracellular hypoxia‐sensing Raman probe. Colloidal stability and surface immobilization were checked using scanning electron microscopy, light scattering, and zeta potential measurements. Site‐specific intracellular hypoxia levels can be estimated in vitro and in vivo using Raman lancets (RL). Distinct Raman spectral changes for the nitro‐(NO2) functional group of the redox marker 4‐nitrothiophenol (4NTP) can be quantified according to the intracellular oxygen (O2) content, ranging from 1 % to 10 %. Redox potential changes in mitochondrial respiration were also examined through serial injections of inhibitors. 3D‐cultured cells and in vivo tests were used to validate our method, and its application in the assessment of the aggressiveness of cancer cells by differentiating spectral changes between malignant and benign cells was demonstrated.

Protein-Templated Core/Shell Au Nanostructures for Intracellular Reactive Oxygen Species Detection by SERS

“…4-ATP has been reported to dimerize due to radical oxidative coupling, forming 4,4′-dimercaptoazobenzene (DMAB) through a diazonium between adjacent 4-ATP that can be detected and differentiated from 4-ATP using SERS (Figure A) . We first examined in situ ROS detection 4-ATP-[BSANP PG ] via DMAB formation using superoxide free radicals (O 2 •– ) generated from hydrogen peroxide in the presence of a Cu 2+ catalyst .…”

“…Surface-enhanced Raman scattering (SERS) is a sensitive, noninvasive tool for molecular detection and in biological environments . SERS “nanoprobes” have been used to examine interactions between nanomaterials and intracellular environments and to map the cellular distribution in both live cells and fixed cells, providing an interesting platform for multimode imaging and detection. , The few studies conducted on SERS-based ROS detection in cellular environments have demonstrated the promise of this novel approach. − The general strategy involves intracellular ROS-induced chemical reactions of Raman reporter molecules detected by nanostructures designed with SERS “hot spots.” ,, …”

Current Trends of Raman Spectroscopy in Clinic Settings: Opportunities and Challenges

“…This method demonstrates significant potential for diagnosing the aggressiveness of cancer cells. [99] Figure 10c presents a schematic of the fabrication of functional nanotubes and a schematic of the Raman probe for detecting the oxygen content of cancer cells, where (ii) presents a comparison of the oxygen levels at different depths detected by nanoprobes in a mouse model. [100] The characteristics of SERS with fibers and NPs were incorporated into one unit in the above studies.…”

“…b) Similar to (a), the schematic of the synthesis of Au@Cu 2 XS-FA NPs and the imaging treatment process in the mouse model. [99] Copyright 2023, John Wiley and Sons. c) Schematic of the synthesis for the functional nanoprobe and the operating principle of the nanoprobe to detect oxygen levels in cancer cells.…”

A Supersmall Single-Cell Nanosensor for Intracellular K + Detection

“…Inspired by the biological K + channel (Supporting Information Figure S1) and using a nanopipette, [24][25][26][27][28][29][30][31][32] here, we describe a supersmall transmembrane K + nanosensor capable of electrochemical probing of intracellular K + . The nanosensor was engineered by functionalization of a small nanopipette with the G-quadruplex (G4) DNA sequence, which exhibited K + -dependent conformational transformation 33 and [2.2.2-cryptand]-enabled recyclability 34 (Figure 1a).…”