Evaluation of the effect of nitrate and chloride on Cd(II)-induced cell oxidative stress by scanning electrochemical microscopy

An isolated single-particle-based SECM tip interface for single-cell NO sensing

As a key factor in cellular metabolic processes, nitric oxide (NO) is a challenging target for in situ real-time monitoring due to its transient property and short diffusion distance. Scanning electrochemical microscopy (SECM) has unique advantages in single-cell analysis, which can obtain the electrochemical current by scanning the cell surface with a tip microelectrode. In particular, it can further improved the electrochemical response by enhancing the interface properties of its tip. Here, an interface design strategy based on platinum single nanoparticle (Pt NP) was developed, and fluorinated self-assembled monolayers (SAMs) were used to further improve its performance. This modified tip was used as an SECM probe for NO concentration monitoring and morphological imaging of single MCF-7 cells. It has the high sensitivity (164.7 μA/μM·cm²) and good selectivity for NO detection, which benefits from the efficient catalytic properties of Pt NPs and high mass transport and hydrophobic antifouling properties of the interface. Notably, it shows a superior performance in detecting the fluctuation of NO released by a single MCF-7-cell under the stimulation of cadmium (Cd), which demonstrates a promising method for using a single-particle-based tip in SECM applications.