Figure 1 | Scientific Reports

Figure 1

From: Dual color pH probes made from silica and polystyrene nanoparticles and their performance in cell studies

Figure 1The alternative text for this image may have been generated using AI.

Synthesis of the hydrophilic neutral optical pH probe 3 designed for lysosomal targeting and its pH signaling mechanism; (i) 4-(2-Aminoethyl) morpholine, ethanol, 50 °C,5 h; (ii) 1-(2-Aminoethyl) piperazine, triethylamine, pyridine, reflux, overnight. The pH signaling mechanism of 3 relies on an intramolecular photoinduced electron transfer (PET) from the unprotonated nitrogen atoms of the piperazine and morpholine units to the naphthalimide chromophore. Nitrogen protonation results in the blocking of these fluorescence quenching PET processes leading to the appearance of the chromophore’s green fluorescence at acidic pH values as confirmed in the following sections.

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