Near-Infrared Fluoride Sensing Nano-Optodes and Distance-Based Hydrogels Containing Aluminum-Phthalocyanine

Abstract

Fluoride ions are highly relevant in environmental and biological sciences, and there is a very limited number of established fluoride chemical sensors. Previous fluoride-selective optodes were demonstrated with metal-porphyrin as the ionophore and required a chromoionophore for optical signal transduction. We demonstrate here novel optical fluoride sensing with nano-optodes containing an aluminum-phthalocyanine complex (AlClPc) as the single active sensing component, simplifying the conventional ion-selective optodes approach. The fluoride nano-optodes were interrogated in the absorbance and fluorescence modes in the near-infrared region, with absorption around 725 nm and emission peaks at 720 and 800 nm, respectively. The nano-optodes exhibited a lower detection limit around 0.1 μM and good selectivity over a range of common anions including ClO 4 − , Cl − , Br − , I − , SO 4 2− , NO 3 − , and AcO − . Furthermore, the nano-optodes were physically entrapped in agarose hydrogels to allow distance-based point-of-care testing (POCT) applications. The 3D networks of the agarose hydrogel were able to filter off large particulates in the samples without stopping fluoride ions to reach the nano-optodes. The fluoride concentrations in real samples including river water, mineral water, and groundwater were successfully determined with the distance-based sensing hydrogel, and the results agreed well with those from commercial fluoride electrodes. Therefore, the results in this work lay the groundwork for the optical detection of fluoride in environmental samples without very sophisticated sample manipulation.

Development of Optical Nanosensors for Detection of Potassium Ions and Assessment of Their Biocompatibility with Corneal Epithelial Cells

“…Various nanomaterials have been used in the fabrication of fluorescent nanosensors. , Interest in the optical probes for detection of potassium ion level has increased due to their simplicity and sensitivity . Optical materials such as dyes and fluorophores have been developed for colorimetric and fluorescent detection of potassium ions in blood, serum, and urine samples. − These materials allow optical detection within the visible range via a turn-on response or color changes.…”