Symbolic image for different, colored nanosensors
Source: Isabella Tavernaro (Division Biophotonics 1.2)
The acid concentration, represented by the pH value, has a decisive influence on many chemical and biological processes and plays an important role in various areas of material, life, and environmental sciences. To determine the pH value in situ using highly sensitive optical methods, pH-sensitive particles are ideal candidates that are non-toxic and small enough to allow a spatially resolved monitoring of pH values. Typically, such sensor particles constitute of a carrier material, i.e., the particle matrix, and analyte-sensitive molecules. The latter change their optical properties, e.g., the color of their fluorescence, selectively, fast, and reversibly in the presence of this analyte and can therefore optically signal the presence of this analyte and changes in its concentration. A systematic comparison between two carrier materials frequently used for pH nanosensors, silica and polystyrene, was performed with the goal to identify possible influences of the particle matrix on the performance of such sensor particles. Therefore, it was ensured that both sensor particle systems exhibit similar physico-chemical and optical properties. Special emphasis was dedicated to the surface chemistry of the sensor particles, as the particle surface chemistry has a significant influence on the interaction of the particles with the environment, and therefore also on their potential toxicity and fate, e.g., in cells, biofilms or other biological systems.
Studies with epithelial cells show that both sensor particles are taken up by the cells, but the uptake of the silica sensor particles was somewhat more efficient. The silica particles also exhibit a better long-term and pH stability than the polystyrene particles, which degraded over time. This underlines the importance of comparative studies and stability studies to identify best suited materials and possible risks originating from nanoparticle degradation and the resulting decomposition products. BAM, as an institution for materials research and testing, plays an important role in the investigation of the safe use and suitability of sensor particles of different sizes and chemical compositions in the material and life sciences. The thereby gained knowledge can help to identify the best, sustainable, most environmentally friendly, and safest solutions for scientific challenges.
Dual color pH probes made from silica and polystyrene nanoparticles and their performance in cell studies
Priyanka Srivastava, Isabella Tavernaro, Lena Scholtz, C. Genger, P. Welker, Frank Schreiber, Klas Meyer, Ute Resch-Genger
published in: Scientific Reports, 2023, pages 1321 - 1336
BAM Department Analytical Chemistry; Reference Materials
BAM Division Biophotonics
BAM Division Process Analytical Technology
BAM Department Materials and the Environment
BAM Division Biodeterioration and Reference Organisms