CdSe/ZnS quantum dots-doped polymer optical fiber microprobe for pH sensing.

pH is an important physiological parameter within organisms, playing a crucial role in functional activities in cells and tissues. Among various pH sensing methods, optical fiber pH sensors have gained a wide attention due to their unique advantages. However, current silica optical fiber-based pH sensors face some challenges such as weak biocompatibility, low biological safety, complex or unstable surface modification. Herein, we develop what we believe to be a novel pH sensor based on a CdSe/ZnS quantum dots-doped polymer optical fiber microprobe (POF MP) grown at the end of the silica optical fiber using the free radical photopolymerization process, which has the advantages of significant compactness, high flexibility, good biocompatibility, easy functionalization, high structural stability and safety. Moreover, the size of the POF MP are controllable, which is highly significant for applications requiring specific probe sizes or those used in special terrains. The proposed sensor is demonstrated to have a sensitivity of 0.18097/pH in a wide pH range from 4.5 to 9.0, while it exhibits a highly linear correlation between fluorescence intensity and pH value (R ² = 0.99448) and good reversibility and reusability. This proposed pH sensor offers a promising solution for pH monitoring in biological environments, contributing to advancements in biosensing, microenvironment monitoring, and potential therapeutic applications.