pH Sensors

pH in microenvironments can be determined with Surflay's sensor particles  by simple fluorescence microscopy. This can be done by determining the fluorescence lifetime as well as monitoring the emission intensity. In the latter, both the pH and the signal are determined within a particle matrix, as referenced. In addition to the bio and medical relevant pH range of 4.5 to 7.5 we offer extended pH range sensors, i.e.: > 8 and <4. With respect to the excitation wavelengths different solutions can be offered so that you can work with popular laser systems or custom optical systems.

Figure: Fluorescence images of pH-sensitive particles (9 ╬╝m); left pH-sensitive fluorescence channel (excitation laser 488 nm, emission range 490-600 nm); right reference fluorescence channel (excitation laser 635 nm, emission range 650-700 nm)

The signals are reversible and also allow the visualisation of the pH gradient. So, for example it is possible not only to determine pH differences between hair roots and hair shaft, but also to optically visualise the differences.

Figure: Fluorescence micrograph of a human hair surrounded by an aqueous suspension of particles, overlay of transmission and the two fluorescence channels for pH measurement and referencing

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