Citric Acid Derived Carbon Dots, the Challenge of Understanding the Synthesis-Structure Relationship

Ren, Junkai; Malfatti, Luca; Innocenzi, Plinio

doi:10.3390/c7010002

Cited by 61 publications

(47 citation statements)

References 106 publications

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“…To get further design principles for future preparations of fluorescent functional nanoparticles, this Box is focused on one of the most utilized precursor for the synthesis of CDs, citric acid (CA). 179 CA has been used as single-source or in multi-component reactions under various thermal treatments. Pyrolysis of only citric acid yields blue FL nanoparticles, with higher temperatures leading to more graphitization.…”

Section: Box 2 Citric Acid As Model Precursor In the Synthesis Of Cdsmentioning

confidence: 99%

A multifunctional chemical toolbox to engineer carbon dots for biomedical and energy applications

et al. 2022

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Photoluminescent carbon nanomaterials, or carbon dots (CDs), are an emerging class of materials that has recently attracted considerable attention for biomedical and energy applications. They are defined by characteristic sizes of <10 nm, a carbon-based core, and the possibility to add various functional groups at their surface for targeted applications. These nanomaterials possess many interesting physicochemical and optical properties, including tuneable light emission, dispersibility and low toxicity. In this Review, we categorize how chemical tools impact the properties of CDs. We look for pre-and post-synthetic approaches for the preparation of CDs and their derivatives or composites. We then showcase examples to correlate structure, composition, and function and use them to discuss the future development for this class of nanomaterials. monomer/polymer as starting materials. Historically, the top-down strategy was first exploited and consisted mainly of electrochemical or chemical oxidation of graphite. 7 While these approaches can yield relatively large quantities of CDs, they usually employ harsh conditions (in terms of voltage applied or chemical oxidant used), long synthetic times, and still need post-synthetic procedures to tune the optoelectronic properties. From the fluorescence perspective, oxidative cutting of carbon sources leads to more structural defects, resulting in less appealing photoluminescence properties.Currently, the bottom-up syntheses are more popular and will be the focus of this Review. In addition to the multitude of molecular precursors available, other benefits include multiple choices of thermal treatments, quicker reaction times, and more uniform properties in the final material. The choice of precursors and synthetic procedures (i.e. pre-synthetic control) affects the physicochemical properties of CDs in terms of size, graphitization degree, surface functional groups, and doping. Nevertheless, the structural features of the precursors can be retained in the nanoparticles, allowing for some degree of predictability. Single-component, to a certain extent, and multi-component reactions enable the use of straightforward doping strategies. These include heteroatoms (examples here include boron, nitrogen, sulfur, selenium, or a combination of them) and metals (such as lanthanides).Besides pre-synthetic control, engineering the surface composition via post-synthetic approaches is a promising way to optimize and expand the utilization of CDs (Fig. 1b). Post-synthetic strategies usually affect the surface functional groups of the CDs since they are generally inefficient in changing properties and chemical composition of the core. Exploiting their surface chemistry also prompted the development of multifunctional CD-based materials (Fig. 1c).There are many excellent sources of information about the intricacies of CDs properties [7][8][9][10][11] and their applications, [12][13][14][15][16] as well as their progress in comparison to traditional inorganic quantum dots. 17 At first, emphas...

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Section: Box 2 Citric Acid As Model Precursor In the Synthesis Of Cdsmentioning

confidence: 99%

A multifunctional chemical toolbox to engineer carbon dots for biomedical and energy applications

et al. 2022

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“…The most intense absorption at around 205 nm is assigned to π-π* 4 transitions, whilst the band at 327 nm is attributed to n –π*. These particular features are characteristic of CA [ 18 , 19 ] and tris-derived C-dots, which have been proved to have a carbon core and amorphous sp 3 whose extension depends on the synthesis conditions [ 13 , 14 ]. The comparison of the UV-Vis spectra confirms that arginine can also undergo similar interactions to tris with citric acid under the same reaction conditions.…”

Section: Resultsmentioning

confidence: 99%

Highly Photostable Carbon Dots from Citric Acid for Bioimaging

et al. 2022

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Bioimaging supported by nanoparticles requires low cost, highly emissive and photostable systems with low cytotoxicity. Carbon dots (C-dots) offer a possible solution, even if controlling their properties is not always straightforward, not to mention their potentially simple synthesis and the fact that they do not exhibit long-term photostability in general. In the present work, we synthesized two C-dots starting from citric acid and tris (hydroxymethyl)-aminomethane (tris) or arginine methyl ester dihydrochloride. Cellular uptake and bioimaging were tested in vitro using murine neuroblastoma and ovine fibroblast cells. The C-dots are highly biocompatible, and after 24 h of incubation with the cells, 100% viability was still observed. Furthermore, the C-dots synthesized using tris have an average dimension of 2 nm, a quantum yield of 37%, high photostability and a zeta potential (ζ) around −12 mV. These properties favor cellular uptake without damaging cells and allow for very effective bioimaging.

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“…Other renewable sources are reviewed elsewhere [ 67 ]. However, the most conventional sources are commercial precursors, such as citric acid [ 68 , 69 , 70 , 71 , 72 , 73 , 74 ], glucose [ 75 , 76 , 77 , 78 ], ascorbic acid [ 79 , 80 ], polyethylene glycol [ 81 , 82 ], and ethylene glycol [ 83 ]. Other heteroatom-containing precursors, such as urea [ 68 , 84 , 85 , 86 , 87 , 88 , 89 , 90 ] chitosan [ 91 , 92 , 93 , 94 ], ethylenediamine [ 37 , 71 , 73 , 77 , 95 ], thiourea [ 72 , 96 ], cysteine [ 74 ], cetrimonium bromide (CTAB) [ 97 ], phenylenediamine [ 98 ], ammonium citrate [ 99 ], and nitropyrene [ 100 , 101 ] are used to dope the CDs with Nitrogen and/or Sulphur (N-CDs, S-CDs and N,S-CDs).…”

Section: Strategies For Cds Synthesismentioning

confidence: 99%

Applications of Carbon Dots for the Photocatalytic and Electrocatalytic Reduction of CO2

et al. 2022

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The photocatalytic and electrocatalytic conversion of CO2 has the potential to provide valuable products, such as chemicals or fuels of interest, at low cost while maintaining a circular carbon cycle. In this context, carbon dots possess optical and electrochemical properties that make them suitable candidates to participate in the reaction, either as a single component or forming part of more elaborate catalytic systems. In this review, we describe several strategies where the carbon dots participate, both with amorphous and graphitic structures, in the photocatalysis or electrochemical catalysis of CO2 to provide different carbon-containing products of interest. The role of the carbon dots is analyzed as a function of their redox and light absorption characteristics and their complementarity with other known catalytic systems. Moreover, detailed information about synthetic procedures is also reviewed.

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Citric Acid Derived Carbon Dots, the Challenge of Understanding the Synthesis-Structure Relationship

Cited by 61 publications

References 106 publications

A multifunctional chemical toolbox to engineer carbon dots for biomedical and energy applications

A multifunctional chemical toolbox to engineer carbon dots for biomedical and energy applications

Highly Photostable Carbon Dots from Citric Acid for Bioimaging

Applications of Carbon Dots for the Photocatalytic and Electrocatalytic Reduction of CO2

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