Evaluation of fluorescent polysaccharide nanoparticles for pH-sensing

Area of Science:

• Nanotechnology
• Analytical Chemistry
• Biomedical Sensing

Background:

• Developing precise pH sensors is crucial for physiological and analytical applications.
• Dextran nanoparticles offer a versatile matrix for encapsulating sensing elements.
• Fluorescent dyes are widely used for real-time monitoring of chemical environments.

Purpose of the Study:

• To characterize novel dextran nanoparticles for their efficacy as pH-sensors.
• To evaluate the suitability of these nanosensors for analytical and physiological measurements.
• To assess the impact of the dextran matrix on sensor performance.

Main Methods:

• Dextran nanoparticles were synthesized and labeled with fluorescein isothiocyanate (FITC) as a pH indicator and sulforhodamine B as a reference dye.
• Fluorescence intensity ratios were measured across a range of pH values.
• The influence of temperature, ionic strength, and oxidizing agents on dye performance was investigated.
• Dextran nanoparticle sensor performance was compared to free dyes.

Main Results:

• The ratio of FITC fluorescence to the reference dye signal exhibited a clear pH-dependent response.
• A pKa value of 6.45 was determined, suitable for many biological applications.
• The dextran matrix minimally affected the fluorescence properties of the encapsulated dyes.
• The nanosensors demonstrated stability against variations in temperature, ionic strength, and oxidizing substances.

Conclusions:

• The developed dextran nanoparticles are effective and stable pH-sensors.
• These nanosensors show significant promise for pH monitoring in biological samples.
• The internal standard approach enhances the reliability of the pH measurements.