Triphenylphosphonium‐Derived Bright Green Fluorescent Carbon Dots for Mitochondrial Targeting and Rapid Selective Detection of Tetracycline

Abstract

Although various fluorescent‐based nanoparticles are treated as cellular imaging probes, approaching the construction of a biocompatible subcellular imaging probe is challenging. At the same time, the recognition of wasted pharmaceutical drugs by some fluorescent nanoprobes is important and urgently required. We report a “structural memory” concept for simple one‐pot synthesis of bright green fluorescent (quantum yield of up to 61%) carbon dots (C‐dots) from triphenylphosphonium (TPP) as a carbon precursor that will simultaneously act as an effective vehicle for mitochondria labeling in cancer cells and as a selective tetracycline sensor. The ubiquitous TPP residues upon the C‐dots’ surface easily recognize the cellular mitochondria. Tetracycline has been selectively and instantaneously detected through rapid fluorescence on‐off response from C‐dots where other drugs remained silent in nature, even after longer incubation. This quenching response is ascribed to the static quenching effect and position of functional groups of the targeted drug which can play a dominating role. The reason for strong fluorescence exhibition from C‐dots has been well explained by considering different factors. Such types of C‐dots have been shown to be universal mitochondria‐targeting nanoprobes, non‐cytotoxic, and effective as a tetracycline detector. This finding should open a new avenue for in‐vivo therapeutic application and sensing of pharmaceutical drugs in real clinical applications.

Highly Luminescent Nucleoside-Based N, P-Doped Carbon Dots for Sensitive Detection of Ions and Bioimaging

“…To further clarify this deduction, UV/vis absorption spectra, FT-IR, and zeta-potential analysis were implemented. Absorption spectra of N/P CDs were notably affected and changed after the addition of Fe 3+ ( Figure 4B ), which was attributable to the strong chemical interaction between Fe 3+ and N/P CDs followed by stable metal complex formation ( Rajendran et al, 2021 ). Absorption peaks of N/P CDs shifted to their former position again with the addition of F − .…”

Yellow Fluorescent Carbon Dots for Selective Recognition of As3+ and Fe3+ Ions

“…This is ascribed to the relatively uniform size and surfacepassivated C-dots which supply a narrow distribution of surface energy states. 43,44 The TEM image in Figure 1C reveals the formation of small-sized nanoparticles of less than 10 nm. The crystalline graphitic organization of the C-dots with an interplanar d spacing of 0.215 nm in the HRTEM image (inset) is representative of [110] graphitic planes.…”

“…These are assigned to sp 2 and sp 3 carbons, respectively. 46 The N 1s spectrum has a peak at 398.6 eV as shown in Figure 2B, corresponding to C−N and/or CN groups, 44 whereas the deconvoluted O 1s peaks at 529.7 and 531.2 eV are assigned to CO and C−OH groups, respectively, in Figure 2C. 46 The presence of the elements was also confirmed by elemental analysis, the weight percentage of C:H:N was 65:1:8.…”

“…The changes in the absorbance spectroscopy results by the interaction of analyte were related to the static quenching as indicated in previous reports. 44,61 The emergence of the ground state complex led to the changes of the C-dots absorbance spectra. 62 On the other hand, other ions exhibited ineffectiveness of the absorbance spectra.…”

Quaternary ammonium‐based mitochondria targeting anticancer agents with high water solubility

“…8 Triphenylphosphonium (TPP) moiety, a substance commonly used to target mitochondria, does not have biological activity but interacts with phospholipids components. [9][10][11] Interestingly, certain TPP derivatives have a negative effect on mitochondrial membrane potential and respiratory chain activity. 12 For example, Trnka et al reported that TPP-alkyl derivatives induce increased proton leak and decreased activity of electron chain complexes, causing mitochondrial dysfunction.…”