Luminescent Carbon Nanodots: Emergent Nanolights

TLDR

Carbon nanodots (C‑dots) are surface‑passivated carbonaceous quantum dots that, like fullerene, nanotube, and graphene, exhibit size‑ and wavelength‑dependent luminescence, resistance to photobleaching, and ease of bioconjugation without the toxicity, scarcity, or complex synthesis required for traditional semiconductor quantum dots. The review summarizes recent advances in C‑dot synthesis and characterization and speculates on future applications in energy conversion, bioimaging, drug delivery, sensors, diagnostics, and composites. C‑dots can be produced inexpensively and at scale via one‑step pathways from biomass waste, using simple candle burning, in‑situ dehydration, or laser ablation techniques.

Abstract

Similar to its popular older cousins the fullerene, the carbon nanotube, and graphene, the latest form of nanocarbon, the carbon nanodot, is inspiring intensive research efforts in its own right. These surface-passivated carbonaceous quantum dots, so-called C-dots, combine several favorable attributes of traditional semiconductor-based quantum dots (namely, size- and wavelength-dependent luminescence emission, resistance to photobleaching, ease of bioconjugation) without incurring the burden of intrinsic toxicity or elemental scarcity and without the need for stringent, intricate, tedious, costly, or inefficient preparation steps. C-dots can be produced inexpensively and on a large scale (frequently using a one-step pathway and potentially from biomass waste-derived sources) by many approaches, ranging from simple candle burning to in situ dehydration reactions to laser ablation methods. In this Review, we summarize recent advances in the synthesis and characterization of C-dots. We also speculate on their future and discuss potential developments for their use in energy conversion/storage, bioimaging, drug delivery, sensors, diagnostics, and composites.