Revealing two chemical strategies to tune bright one- and two-photon excited fluorescence of carbon nanodots

Abstract

Carbon-based dots (CDs) are a novel class of luminescent carbon nanomaterials, attracting much interest as promising alternatives for cadmium-based quantum dots and fluorescent organic dyes. Although different strategies have been...

Three-Dimensional Imaging of Bioinspired Lipidic Mesophases Using Multicolored Light-Emitting Carbon Nanodots

“…Verification of the character of the observed process was revealed by detecting the luminescence intensity at a series of low excitation powers (<3 mW) for all tested fractions of PG CNDs in the DLPC matrix. The linear dependencies with the slope of ∼2 for the double logarithmic plots of emission intensity vs average excitation laser power indicated the two-photon nature of the processes involved in all samples (Figure a), comparable with the slope values for pure CNDs in the MeOH . Next, the two-photon excited (TPE) fluorescence spectra of PG CNDs in the lipidic matrix were performed upon excitation in the NIR-I region.…”

“…The studies were performed on structures marked with YELLOW CNDs (0.1−1.0 mg/mL), nanostructures with the highest contribution of oxygenous groups, and solvent-responsive fluorescence properties. 49 Nearly homogeneous emission detected along walls of characteristic MFs formed with YELLOW CNDs (even with their initial concentrations of 1 mg/mL) indicated uniform NP distribution within the hydrophobic parts of investigated lipidic mesophases (Figure 2c). The first experiments were carried out on DMPC-based MFs after adding an aqueous phase at pH 1 and 7.…”

“…Their extensive structural characterization unravelled the predominant role of nonpolar carbogenic domains. 49 Selected PG CNDs exhibit monochromatic and tunable emission colors in low-carbon alcohols, as evidenced by the narrow emission bands at 478 nm (CYAN CNDs), 509 nm (GREEN CNDs), and 550 nm (YELLOW CNDs) in Figure S1. PG CNDs are excellent fluorophores (e.g., the QY of CYAN CNDs is around 62% in methanol (MeOH) dispersion and 34% in Tris Buffer) and efficient two-photon absorbers (e.g.…”

“…In the case of YELLOW CNDs, the FWHMvalue is comparable with Nile Red’s value. Moreover, these yellow-emitting NPs have a significant Stokes shift (3186 cm –1 ), which may benefit multiplex imaging. ,, Furthermore, PG CNDs show excellent photostability under prolonged illuminations. As illustrated by the example of YELLOW CNDs in comparison with Nile Red (Figure S2b), CNDs exposed to continuous NIR-irradiation with the pulsed laser beam (λ = 740 nm, P laser = 10 mW) also maintain a high fluorescence intensity.…”

“…Furthermore, PG CNDs consist of polar (e.g., hydroxyl groups) and nonpolar (methyl and methylene moieties) structural units. Their extensive structural characterization unravelled the predominant role of nonpolar carbogenic domains …”