Highly fluorescent Zn-doped carbon dots as Fenton reaction-based bio-sensors: an integrative experimental–theoretical consideration

Abstract

Heteroatom doped carbon dots (CDs), with high photoluminescence quantum yield (PLQY), are of keen interest in various applications such as chemical sensors, bio-imaging, electronics, and photovoltaics. Zinc, an important element assisting the electron-transfer process and an essential trace element for cells, is a promising metal dopant for CDs, which could potentially lead to multifunctional CDs. In this contribution, we report a single-step, high efficiency, hydrothermal method to synthesize Zn-doped carbon dots (Zn-CDs) with a superior PLQY. The PLQY and luminescence characteristic of Zn-CDs can be tuned by controlling the precursor ratio, and the surface oxidation in the CDs. Though a few studies have reported metal doped CDs with good PLQY, the as prepared Zn-Cds in the present method exhibited a PLQY up to 32.3%. To the best of our knowledge, there is no report regarding the facile preparation of single metal-doped CDs with a QY more than 30%. Another unique attribute of the Zn-CDs is the high monodispersity and the resultant highly robust excitation-independent luminescence that is stable over a broad range of pH values. Spectroscopic investigations indicated that the superior PLQY and luminescence of Zn-CDs are due to the heteroatom directed, oxidized carbon-based surface passivation. Furthermore, we developed a novel and sensitive biosensor for the detection of hydrogen peroxide and glucose leveraging the robust fluorescence properties of Zn-CDs. Under optimal conditions, Zn-CDs demonstrated high sensitivity and response to hydrogen peroxide and glucose over a wide range of concentrations, with a linear range of 10-80 μM and 5-100 μM, respectively, indicating their great potential as a fluorescent probe for chemical sensing.

Dramatic red fluorescence enhancement and emission red shift of carbon dots following Zn/ZnO decoration

“…It is well known that the presence of –OH and C=O plays important roles in CD fluorescence intensity . When Zn was added into the precursor, it can reduce –OH and conversely Zn is oxidized.…”

“…Cheng and colleagues synthesized Zn‐doped CDs using zinc ions/citric acid that yielded yellow luminescence with a PLQY of 51.2% . Moreover, Xu and colleagues reported Zn‐doped CDs derived from sodium citrate/zinc chloride with a PLQY of 32.3% (blue fluorescence) . To the best of our knowledge, there are few reports on the preparation of Zn/ZnO‐decorated CDs with long‐wavelength emission and high PLQY.…”

The toxicity of ZnO nanomaterials to HepG2 cells: the influence of size and shape of particles

“…They are also excellent sunscreen agents due to their UV light absorbing properties and transparency for visible light (Kim et al, ). In biomedicine, ZnO NMs could also be potentially used as biosensors (Xu et al, ), antibacterial agents (Wang, Hu, & Shao, ) and novel nanocarriers for drug delivery (Mishra, Mishra, Ekielski, Talegaonkar, & Vaidya, ). Thus, the exposure of human beings to ZnO NMs is likely increasing in modern societies, and it is necessary to study the potential toxic effects of ZnO NMs as well as the underlying mechanisms.…”

Difunctional Cu-doped carbon dots: catalytic activity and fluorescence indication for the reduction reaction of p-nitrophenol

“…21 Doping with gadolinium was demonstrated to be used as a magnetic resonance imaging positive contrast agent. 22 Moreover, Zn-doped CDs can be served as a uorescent probe for the detection of H 2 O 2 and glucose based on the Fenton reaction 23 while doping with both Cu and N atoms can be acted as a novel photocatalyst because of the enhanced electron-accepting and donating ability. 24 Inspired by these observations, herein, we report the preparation of Cu-doped CDs by a one-step hydrothermal carbonization of CuCl 2 $2H 2 O and ethylenediaminetetraacetic acid disodium salt dihydrate (EDTA).…”