Magnetic Rhodamine B-Imprinted Polyacrylamide pH Probe Using Resonance Rayleigh Scattering

Area of Science:

• Materials Science
• Analytical Chemistry
• Nanotechnology

Background:

• Developing sensitive and selective sensors for environmental and food monitoring is crucial.
• Molecularly imprinted polymers (MIPs) offer tailored recognition sites for specific analytes.
• Magnetic nanoparticles provide a platform for easy separation and potential for enhanced sensing.

Purpose of the Study:

• To develop a novel nanosurface molecularly imprinted polyacrylamide nanoprobe (Fe3O4@MIPB) for pH sensing.
• To utilize rhodamine B (RhB) as both a template and sensing molecule within the imprinted polymer.
• To establish a new pH sensing platform based on resonance Rayleigh scattering (RRS) coupled with magnetic nanoparticles.

Main Methods:

• Preparation of Fe3O4@MIPB using Fe3O4 magnetic nanoparticles, RhB, acrylamide (AM), and ethylene glycol dimethacrylate (EGDMA).
• Characterization using scanning electron microscopy (SEM), hysteresis loop, Fourier transform infrared spectroscopy (FT-IR), and RRS spectroscopy.
• Quantification of pH by monitoring changes in RRS intensity at 375 nm due to RRS-energy transfer (RRS-ET) effects.

Main Results:

• The Fe3O4@MIPB nanoprobe showed a strong RRS peak at 375 nm.
• A linear decrease in RRS intensity was observed with increasing pH in the range of 2.2-6.2, attributed to enhanced RRS-ET.
• Further linear decrease in RRS intensity was observed in the pH range of 7.0-9.8.
• The sensor demonstrated low relative standard deviations (RSDs) for pH detection in Li River water (0.43-1.4%) and food samples (0.28-4.1%).

Conclusions:

• A novel RhB-imprinted magnetic molecularly imprinted polymer combined with RRS for pH detection was successfully developed.
• The developed sensor exhibits high sensitivity, a wide pH detection range, and excellent selectivity and stability in complex matrices.
• This approach offers a promising new method for pH detection in real-world samples.