Thin PEGylated Carbon Nitrides: Water‐Dispersible Organic Nanodots as Bioimaging Probes

Abstract

Fluorescent materials are being used for the optical/fluorescence imaging of living cells and animal models. As such, the development of heavy-metal-free, water-dispersible, and biocompatible imaging probes is still important. Carbon nitride (C N ) is used as a bioimaging probe due to its suitable optical properties, thus enhancing its biocompatibility and dispersibility in aqueous media is required. In this study, we incorporated short-chain polyethylene glycol (PEG) groups onto a carbon nitride network by the simple N-alkylation of hexaethylene glycolic mesylate with nucleophilic nitrogen atoms on oxidized carbon nitride (OCN). The PEGylated OCN (PEG-OCN) was well dispersed in water as nanodots with a lateral dimension of approximately 30 nm and a thickness of 0.5-1.2 nm and showed strong photoluminescence in the visible region. Cell-viability testing confirmed that these "heavy-metal-free" organic nanodots were highly biocompatible and noncytotoxic. In particular, the developed nanodots could provide clear confocal images of RAW 264.7 cells without weakening cell activity and displaying any aggregation in a range of concentrations (25-100 μg mL ) with bright-green emission in the cytoplasm.

Graphitic carbon nitride and polymers: a mutual combination for advanced properties

“…2). 75 Well dispersed colloids ( Fig. 2a) with high biocompatibility and bioimaging properties could be achieved in that way (Fig.…”

“…(25, 50, and 100 mg mL À1 ) for 24 h at 37 1C (Reprinted with permission. 75 Copyright 2018 John Wiley and Sons). (c) Allylamine-modified g-C 3 N 4 in water (1 wt%) at acidic pH (pH = 4), observation of immediate precipitation after base addition (pH = 9), complete sedimentation after standing for 2 h, and redispersion after reacidification (pH = 4) (Reprinted with permission.…”

Production of Metal‐Free C, N Alternating Nanoplatelets and Their In Vivo Fluorescence Imaging Performance without Labeling

“…[6,7,[21][22][23][24] Recently, chemical modification of 3D C 3 N 4 networks and insertion of solvent molecules into interlayer galleries of the 3D network provided successful routes for producing exfoliated 2D C 3 N 4 -based nanoplatelets. [25][26][27][28][29][30] For example, chemical oxidation of 3D C 3 N 4 , [25] or attachment of a biocompatible and flexible group such as polyethylene glycol on 3D C 3 N 4 provided aqueous homogeneous colloidal suspensions of 2D C 3 N 4based nanoplatelets. [26] These 2D materials were luminescent in aqueous media and showed good performance for in vitro cell imaging.…”

“…[25][26][27][28][29][30] For example, chemical oxidation of 3D C 3 N 4 , [25] or attachment of a biocompatible and flexible group such as polyethylene glycol on 3D C 3 N 4 provided aqueous homogeneous colloidal suspensions of 2D C 3 N 4based nanoplatelets. [26] These 2D materials were luminescent in aqueous media and showed good performance for in vitro cell imaging. However, in vivo fluorescence imaging attempts with the dispersed materials has not been successful, presumably because of low dispersion stability of hydrophobic sp 2 CN networks.…”

Grafting Polymers onto Carbon Nitride via Visible-Light-Induced Photofunctionalization

“…Generally studied as a heterogeneous photocatalyst, g-CN can be used in water splitting, 4−6 CO 2 reduction, 3,7 and pollution photodegradation. 8−10 The unique optical properties such as photoluminescence 11−13 and biocompatibility 14 make g-CN an ideal candidate for bioimaging 15,16 and biomedical 17 applications. Recently, two-dimensional g-CN films have been frequently studied 18 and have broad applications in solar cells, 19 ionic devices, 20 and sensing.…”