Xu Zhang,Jingjing Yao,Yueer Yan,Yahong Zhang,Yi Tang,Yuliang Yang
Paper-based cultural relics often undergo acidification and deterioration during long-term preservation. Accurate detection of paper acidity is of great significance to assess aging status and extend the preservation lifetime of paper-based cultural relics. Rapid identification of the acidification degree and acid distribution across multiple regions of paper is essential. Inspired by fluorescent sensing technology, pH-sensitive cadmium telluride (CdTe) quantum dots (QDs) and rhodamine B (RB) fluorescent probes are synthesized and incorporated onto the nanofibers of a bacterial cellulose (BC) membrane to enable visual acidity detection of paper. Due to the complementary pH detection range of CdTe QDs and RB probes, the composite BC membrane exhibits a clear pH response across an acidic to neutral range (pH 3.0–7.5). Notably, the contrasting fluorescent colors of the two probes within the BC membrane allow for easy visualization of paper pH and acidity distribution with the naked eyes. A distinct color transition from red to green was observed on the fluorescent BC membrane when it is applied to a model paper with a gradient pH distribution. The feasibility of this method was verified by using the flat-headed pH electrode method. Additionally, common metal ions in most paper fillers, inks, pigments, as well as some sugars and amino acids showed minimal interference with the pH response of the composite BC membrane, highlighting its potential and broad applicability for visual acidity detection in paper-based cultural relics.
pH detection plays a critical role in human health monitoring, environmental protection and energy conservation. Herein, water-soluble porphyrin derivative nanoparticles (WSPD NPs) were successfully synthesized, exhibiting a ratiometric fluorescent response in acidic aqueous solutions with a significant fluorescence color change from red to orange as pH values decreased from 4 to 2. Notably, WSPD NPs displayed similar fluorescence behavior in various acidic organic solvents. The pH-responsive mechanism is attributed to the protonation of pyrrolic nitrogen, a process unaffected by solvent species. WSPD NPs possessed excellent biocompatibility with low cytotoxicity and efficient cellular uptake for intracellular pH imaging. Furthermore, their good solubility and photostability in battery electrolytes allowed for pH detection in sodium (Na) half-cells. The developed WSPD NPs test strips for convenient and visual pH sensing obtained satisfactory results in different acidic solvents, and the fluorescence messages could be stored for a week, while avoiding damage to the pH meter and addressing the short preservation time of commercial pH test strips. This WSPD NPs-based ratiometric fluorescent nanoprobe realized a rapid response for pH detection under various acidic conditions, accompanied by the fluorescence color changes discernible to the naked eye. Its versatility allows for applications in drinking beverage samples, pH sensing test strips, living cells, and battery electrolytes.
危险品化学品经营许可证（带存储）