Dual-Purpose Sensing Nanoprobe Based on Carbon Dots from o-Phenylenediamine: pH and Solvent Polarity Measurement

Abstract

Today, the development of nanomaterials with sensing properties attracts much scientific interest because of the demand for low-cost nontoxic colloidal nanoprobes with high sensitivity and selectivity for various biomedical and environment-related applications. Carbon dots (CDs) are promising candidates for these applications as they demonstrate unique optical properties with intense emissions, biocompatibility, and ease of fabrication. Herein, we developed synthesis protocols to obtain CDs based on o-phenylenediamine with a variety of optical responses depending on additional precursors and changes in the reaction media. The obtained CDs are N-doped (N,S-doped in case of thiourea addition) less than 10 nm spherical particles with emissions observed in the 300–600 nm spectral region depending on their chemical composition. These CDs may act simultaneously as absorptive/fluorescent sensing probes for solvent polarity with ∆S/∆ENT up to 85, for ∆ENT from 0.099 to 1.0 and for pH values in the range of 3.0–8.0, thus opening an opportunity to check the pH in non-pure water or a mixture of solvents. Moreover, CDs preserve their optical properties when embedded in cellulose strips that can be used as sensing probes for fast and easy pH checks. We believe that the resulting dual-purpose sensing nano probes based on CDs will have high demand in various sensing applications.

Carbon Dot Emission Enhancement in Covalent Complexes with Plasmonic Metal Nanoparticles

“…CD-3 was synthesized according to Ref. [ 32 ]. The details of the synthesis procedures are given in the Supporting Information .…”

Energy-level engineering of carbon dots through a post-synthetic treatment with acids and amines

“…For CD-PD, a peak at 420 nm emerges, which is typical of 2,3-diaminophenazine-like moieties. 21,22 From the photoluminescence excitation-emission (PLE-PL) map of CD-s shown in Fig. S4 (ESI), † one can see that the PL band with a maximum at 450 nm is effectively excited at 260 and 360 nm corresponding to the absorption bands.…”

High sensitive assay of formaldehyde using resonance light scattering technique based on carbon dots aggregation

“…including mass of precursors, hydrothermal reaction time and temperature were investigated by reference to literatures (Zhao et al, 2019;Vedernikova et al, 2022;Papaioannou et al, 2019. The reaction time affects the morphology of CDs, no nanometer-sized particles were observed under the reaction time of 6 h. So the reaction time for the synthesis of CDs was 6 h (Papaioannou et al, 2019).…”