Design and characterization of a tricolored nanosensor for pH sensing in solution and in cancer cell lines
Source: BAM, division Biophotonics
Compared to conventional sensors based on organic dyes, nanosensors utilize the unique potential of nanoparticles for signal amplification, enable the use of hydrophobic in aqueous environments, and allow for the combination of multiple dyes with spectroscopically distinguishable properties for multicolor analyte detection. Thereby, also self-referenced or so-called ratiometric nanosensors can be easily fabricated, that measure the optically distinguishable signals of an analyte-insensitive reference dye, incorporated into the particle core, and a sensor dye. Utilizing this design concept, we obtained a novel pH nanosensor, that changes its fluorescence color from blue and red to blue and green in the pH range of 3.0 to 9.0 and enables ratiometric imaging of pH values of different cell compartments. Nanosensor fabrication involved the staining of self-made 50 nm carboxylated polystyrene nanoparticles with a water-insoluble blue-red emissive dyad, which consisted of a red fluorescent rhodamine dye, responsive to acidic pH values, and a pH-inert blue emissive quinoline reference dye. Subsequently, a fluorescein dye signaling neutral and basic pH values with a green emission, was covalently attached to the particle surface. Imaging studies with the pH nanosensor and human lung carcinoma/alveolar cell line A549 revealed its cellular uptake and differently colored emission in different cell organelles. These results underline the potential of the nanosensor to visualize the endosomal-lysosomal pathway. This simple and versatile design concept of multi-color sensor particles demonstrates the underexplored potential of biocompatible polystyrene nanoparticles for sensing and bioimaging applications utilizing hydrophobic and/or hydrophilic stimuli-responsive luminophores.
Multicolor Polystyrene Nanosensors for the Monitoring of Acidic, Neutral, and Basic pH Values and Cellular Uptake Studies
Priyanka Srivastava, Isabella Tavernaro, C. Genger, P. Welker, Oskar Huebner, Ute Resch-Genger
published in Analytical Chemistry, Vol. 94, issue 27, pages 9656 - 9665, 2022.
BAM, department Analytical Chemistry: Referencematerials, division Biophotonics