Multimode Sensing Platform Based on Turn-On Fluorescent Silicon Nanoparticles for Monitoring of Intracellular pH and GSH

Abstract

Various physiological activities and metabolic reactions of cells need to be carried out under the corresponding pH environment. Intracellular GSH as an acid tripeptide and an important reducing substance also plays an important role in maintaining cellular acid–base balance and redox balance. Therefore, developing a method to monitor pH and GSH and their changes in cells is necessary. Herein, we developed a novel turn-on fluorescent silicon nanoparticles (SiNPs) using N-(2-aminoethyl)-3-aminopropyltrimethoxysilane as the silicon source and dithiothreitol as the reducing agent via a one-pot hydrothermal method. It was worth mentioning that the fluorescence intensity of the SiNPs increased along with the acidity increase, making the SiNPs have excellent pH and GSH sensing capability. Furthermore, the pH and GSH sensing performance of the SiNPs in the cell was verified by confocal imaging and flow cytometry experiment. Based on the above, the prepared SiNPs had the potential to be used as an intracellular pH and GSH multimode fluorescent sensing platform and exhibited the ability to distinguish between normal cells and cancer cells.

Designing a Hypoxia-Activated Sensing Platform Using an Azo Group-Triggered Reaction with the Formation of Silicon Nanoparticles

“…Absorption peaks with their corresponding functional groups were illustrated as follows: the O–H stretching feature at 3368 cm –1 , the C–H band at 2932 and 1469 cm –1 , the bending vibration of N–H at 1603 and 783 cm –1 , C–N at 1350 cm –1 , Si–C and Si–O–Si bands at 1031 and 1126 cm –1 , and Si–O–H at 933 cm –1 . Those findings revealed the presence of amino (−NH 2 ) and hydroxy (−OH) groups on the surface of Si NPs, which confirm the water solubility and stability of Si NPs . In addition, the XRD pattern of Si NPs (Figure S3) displayed the amorphous state …”

“…By increasing the excitation wavelength from 330 to 470 nm, a gradual redshift of the emission wavelength was observed from 400 to 600 nm. Such excitation-dependent PL behavior of Si NPs could be attributed to the oxygen-induced defects, which are the distribution of various surface states of nanoparticles …”

“…Silicon has been extensively used in multiple research areas. − In the past two decades, different kinds of silicon nanostructures have been synthesized . Among them, silicon nanoparticles (Si NPs) have proven to be environmentally friendly fluorometric nanosensors. , Such impressive keys allow Si NPs to be considered as a research hot spot in various fields including biological labeling, biosensors, and bioimaging. − …”