Recent Advancements in Metal and Non-Metal Mixed-Doped Carbon Quantum Dots: Synthesis and Emerging Potential Applications

Abstract

In nanotechnology, the synthesis of carbon quantum dots (CQDs) by mixed doping with metals and non-metals has emerged as an appealing path of investigation. This review offers comprehensive insights into the synthesis, properties, and emerging applications of mixed-doped CQDs, underlining their potential for revolutionary advancements in chemical sensing, biosensing, bioimaging, and, thereby, contributing to advancements in diagnostics, therapeutics, and the under standing of complex biological processes. This synergistic combination enhances their sensitivity and selectivity towards specific chemical analytes. The resulting CQDs exhibit remarkable fluorescence properties that can be involved in precise chemical sensing applications. These metal-modified CQDs show their ability in the selective and sensitive detection from Hg to Fe and Mn ions. By influencing their exceptional fluorescence properties, they enable precise detection and monitoring of biomolecules, such as uric acid, cholesterol, and many antibiotics. Moreover, when it comes to bioimaging, these doped CQDs show unique behavior towards detecting cell lines. Their ability to emit light across a wide spectrum enables high-resolution imaging with minimal background noise. We uncover their potential in visualizing different cancer cell lines, offering valuable insights into cancer research and diagnostics. In conclusion, the synthesis of mixed-doped CQDs opens the way for revolutionary advancements in chemical sensing, biosensing, and bioimaging. As we investigate deeper into this field, we unlock new possibilities for diagnostics, therapeutics, and understanding complex biological processes.

Keywords: biosensing; chemical sensing; mixed-doped CQDs; synthesis techniques.

Figure 2

Overview of synthesis of iron, nitrogen co-doped CQDs. (a) Synthesis of Fe-N-CQDs. Reproduced from [23], with permission from Elsevier 2021. (b) Synthesis of Fe/N-CQDs. Reproduced from [27,28], with permission from Elsevier 2022. (c) Synthesis of Fe,N-CDs. Reproduced from [29], with authorization from RSC 2021. (d) Synthesis of Fe@NCDs. reproduced from [30], with permission from Springer 2020. (e) Synthesis of Fe-N-CNP. reproduced from [24], with permission from (f) Synthesis of Fe-N-C. Reproduced from [25], with permission from RSC 2017.

Figure 3

Overview of synthesis of copper and nitrogen co-doped CQDs. (a) Synthesis of Cu-N-CDs. Reproduced from [34], with permission from Elsevier 2020. (b) Synthesis of N,Cu-CD. Reproduced from [31], with permission from Springer 2019. (c) Synthesis of Cu,N@C-dots. Reproduced from [35], with permission from Springer 2022. (d) Synthesis of N/Cu-CDs. Reproduced from [33], with permission from ACS 2017. (e) Synthesis of Cu,N@CQDs. Reproduced from [32], with permission from Springer 2019.

Figure 12

Illustration of cell imaging and monitoring of Fe(III). Reproduced from [29], with permission from RSC 2021.

Figure 1

Illustration of the synthesis and applications of mixed-doped carbon quantum dots.

Figure 4

Overview of synthesis of zinc and nitrogen co-doped CQDs. (a) Synthesis of Zn-N-CQDs. Reproduced from [36,37], with permission from Elsevier 2020. (b,c) Synthesis of N,Zn-CDs. Reproduced from [38], with permission from Elsevier 2019.

Figure 5

Overview of synthesis. (a) Synthesis of Ce-N-CQDs. Reproduced from [40], with permission from Elsevier 2021. (b) Synthesis of Ni-N-C materials. Reproduced from [42], with permission from Elsevier 2019. (c) Synthesis of N,Co-CDs. Reproduced from [43], with permission from ACS 2019. (d) Synthesis of Au/N-CQDs. Reproduced from [44], with permission from Elsevier 2018.

Figure 6

(a,b) Synthesis of Mg-N-CDs. Reproduced from [47,48,49], with permission from RSC 2014, Elsevier 2016.

Figure 7

(a,b) Detection of Hg(II). Reproduced from [44,48], with permission from Elsevier 2016 and 2018. (c) Determination of Mn(VII). Reproduced from [53], with permission from Springer 2019.

Figure 8

(a) Discrimination between OPD and PPD. Reproduced from [31], with permission from Springer 2019. (b) Detection of Fe³⁺. Reproduced from [38], with permission from Elsevier 2019. (c,d) Sensing of Pyrogallol. Reproduced from [32], with permission from Springer 2019.

Figure 9

(a) Detection of Ascorbic acid. Reproduced from [34], with permission from Elsevier 2020. (b) Detection of cholesterol. Reproduced from [33], with permission from ACS 2017. (c) Determination of amoxicilin. Reproduced from [77], with permission from IOPscience 2019.

Figure 10

(a) Determination of OFL. Reproduced from [36], with permission from Elsevier 2020. (b,c) Detection of cholesterol and uric acid. Reproduced from [33], with permission from ACS 2017.

Figure 11

Illustration of bio-imaging of Zr-N-CDs. Reproduced from [54], with permission from Elsevier 2021.