The slit widths of emission and excitation were both 20 nm. The concentration of metals was 10 ppm in all cases. Results obtained from the characterization of C-onions suggested that a possible mechanism for the formation of C-onions may be related to the presence of polyene molecules in tomatoes, carrots and leaves, particularly in the case of tomatoes with a high content of lycopene.
In the case of carrots and tree leaves, the reorganization into onions was not so clear as in the case of tomatoes, although it may be related to the low content of lycopene in these vegetables. We suggest that further investigation of the factors affecting such reorganization must be performed, such as the time of heating, the amount of NaOH or the temperature used, which also will help to improve the yield of the synthesis.
Figure 7: Hypothetical growth of carbon onions from lycopene. C-onions obtained by conventional synthetic methods such as arc-discharge and chemical vapor deposition are insoluble in water, which restricts their use in analytical, biological and biomedical applications. We are aware of the danger of drawing conclusions from preliminary data.
However, we sense that this synthetic procedure has the necessary characteristics for further studies and development of tailor-made water-soluble C-onions from polyene molecules with different functionalities in basic media. Given their closed structure, water soluble C-onions could be loaded with specific molecules or drugs in bio-medical applications while the delivery process could be monitored thanks to their exceptional PL properties.
The field is open. All the reagents used were highly pure analytical grade chemicals and used without further purification.
Tree leaves acer saccharum were taken from the faculty garden. C-nanoparticles were synthesized by a thermal carbonization method using tomatoes, carrots and tree leaves as green carbon sources. Typically, after thoroughly cleaning, the starting material was grinded in small pieces and about 30—50 g was put into dried and cleaned crucibles. The residue was then dissolved in about 25 mL Milli-Q water, filtered through 0.
The color is probably due to the partial oxidation of graphene to graphene oxide during the process . The water-soluble part of the residue was extracted by dissolution in mL deionized water, then filtrated through normal filter papers and followed by nylon filters 0. The filtered solution was then purified through dialyzer tube MWCO, 3.
Each purified solution was divided into two aliquots, the first one was dried completely for characterization analysis dark-brown solid , while the second was used for the analysis experiments. The PL spectra were recorded at nm with excitation at nm for C-dots.
For C-onions the PL measurements were taken at nm with excitation at nm. The PL was measured as mentioned above with the same instrumental settings. A 1 cm quartz cuvette was used. The PL quantum yield was calculated through the well-established comparative method using quinine sulfate as a reference. The following equations were used in the quantum yield measurement:.
Quinine sulphate dissolved in 0.
PL spectra were measured using a Cary Eclipse Varian spectrofluorimeter. UV—vis spectrophotometric analysis was measured with Perkin Elmer, Lambda instrument. Also, G. Gaber Ahmed thanks an Erasmus Mundus Medastar grant.
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Jump to Figure 7. Chemicals and reagents All the reagents used were highly pure analytical grade chemicals and used without further purification. Synthesis of carbon nanoparticles C-nanoparticles were synthesized by a thermal carbonization method using tomatoes, carrots and tree leaves as green carbon sources.
PL quantum yield measurement The PL quantum yield was calculated through the well-established comparative method using quinine sulfate as a reference. The following equations were used in the quantum yield measurement: 2 3 where is the quantum yield, F is the calculated integrated luminescence intensity, n is the refractive index, A is the optical density measured with a UV—vis spectrophotometer, Perkin Elmer, Lambda , and G is the gradient of a linear plot of F as a function of A. Supporting Information.
Supporting Information File 1: Additional experimental data. Format: PDF Size: Interface , 22 3 , 61— Acta , , 51— Talanta , , — Nature , , — Interfaces , 6, — Carbon , 53, — Carbon , 32, — Nanotechnology , 24, Nanotechnology , 22, A , 4, — Pyrolysis , 63, — Carbon , 1, 3—9. Nanotechnology , 2, — Lycopene from tomatoes.
Belshaw, S. Nature Publishing Group. Plasmons in Fullerene Molecules. Politis and Y. Delaunay and B. Optical Spectroscopy of Nanomaterials.
Carbon Onions. Graphene: Synthesis, Functionalization and Properties. State-of-the-art scientific content is enriched with fundamental equations and illustrations. The handbook covers a broad range of topics: Principles and Methods Vol. The handbook consists of chapters and 5, pages. Nanophysics brings together multiple disciplines to determine the structural, electronic, optical, and thermal behavior of nanomaterials; electrical and thermal conductivity; the forces between nanoscale objects; and the transition between classical and quantum behavior.
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