Highly Sensitive Fluorescent pH Microsensors Based on the Ratiometric Dye Pyranine Immobilized on Silica Microparticles. Issue 53 (26th July 2021)

• Record Type: Journal Article
• Authors: Chandra, Anil; Prasad, Saumya; Iuele, Helena; Colella, Francesco; Rizzo, Riccardo; D'Amone, Eliana; Gigli, Giuseppe; del Mercato, Loretta L.
• Is Part Of: Chemistry. Volume 27:Issue 53(2021)
• Page Start: 13318
• Page End: 13324
• Publication Date: 2021-07-26
• Subjects: pH sensors -- HPTS -- microparticles -- fluorescence -- ratiometric sensing.; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.202101568
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: Pyranine (HPTS) is a remarkably interesting pH‐sensitive dye that has been used for plenty of applications. Its high quantum yield and extremely sensitive ratiometric fluorescence against pH change makes it a very favorable for pH‐sensing applications and the development of pH nano‐/microsensors. However, its strong negative charge and lack of easily modifiable functional groups makes it difficult to use with charged substrates such as silica. This study reports a methodology for noncovalent HPTS immobilization on silica microparticles that considers the retention of pH sensitivity as well as the long‐term stability of the pH microsensors. The study emphasizes the importance of surface charge for governing the sensitivity of the immobilized HPTS dye molecules on silica microparticles. The importance of the immobilization methodology, which preserves the sensitivity and stability of the microsensors, is also assessed. Abstract : In a one‐step synthesis, silica microparticles with efficiently immobilized pyranine (HPTS) dye gave extremely sensitive fluorescent ratiometric pH sensors. Immobilizing dye molecules on oppositely charged silica microparticles by using a positively charged silica shell preserves HPTS′S pH sensitivity, and also enhances the stability of the sensor particles. The effect of microparticle surface charge manipulation on enhancing the pH sensitivity without perturbing the stability and cytocompatibility is explored.