TY  - JOUR
AU  - Jovanović, Svetlana P.
AU  - Syrgiannis, Zois
AU  - Budimir, Milica
AU  - Milivojević, Dušan
AU  - Jovanović, Dragana J.
AU  - Pavlović, Vladimir B.
AU  - Papan, Jelena
AU  - Bartenwerfer, Malte
AU  - Mojsin, Marija
AU  - Stevanović, Milena J.
AU  - Todorović-Marković, Biljana
PY  - 2020
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/8672
AB  - Due to their low cost and possible green synthesis, high stability and resistance to photobleaching, graphene quantum dots (GQDs) can be considered as one of the class of carbon nanomaterials which may have great potential as an agent for photosensitized oxygen activation. In such a way, GQDs can be used as a theranostic agent in photodynamic therapy. In this work pristine GQDs, GQDs irradiated with gamma rays and GQDs doped with N and N, S atoms are produced using a simple, green approach. By using different techniques (AFM, HR-TEM, SEM-EDS, FTIR, XRD, PL and UV–Vis) we investigated structural and optical properties of the new types of GQDs. We showed that GQDs functionalized with thiourea (GQDs-TU) completely lost the ability to produce singlet oxygen (1O2) upon photoexcitation while functionalization with urea (GQDs-U) improves the capability of GQDs to produce 1O2 upon the same conditions. Thus, presented GQDs modification with urea seems like a promising approach for the production of the efficient photosensitizer. On the opposite, GQDs-TU are efficient [rad]OH quencher. Due to high singlet oxygen production and low cytotoxicity below 100 μg/mL against HeLa cells, GQDs-U is a good candidate as an agent in photodynamic therapy at this concentration. © 2019
T2  - Materials Science and Engineering: C
T1  - Graphene quantum dots as singlet oxygen producer or radical quencher - The matter of functionalization with urea/thiourea
VL  - 109
SP  - 110539
DO  - 10.1016/j.msec.2019.110539
ER  - 

@article{
author = "Jovanović, Svetlana P. and Syrgiannis, Zois and Budimir, Milica and Milivojević, Dušan and Jovanović, Dragana J. and Pavlović, Vladimir B. and Papan, Jelena and Bartenwerfer, Malte and Mojsin, Marija and Stevanović, Milena J. and Todorović-Marković, Biljana",
year = "2020",
abstract = "Due to their low cost and possible green synthesis, high stability and resistance to photobleaching, graphene quantum dots (GQDs) can be considered as one of the class of carbon nanomaterials which may have great potential as an agent for photosensitized oxygen activation. In such a way, GQDs can be used as a theranostic agent in photodynamic therapy. In this work pristine GQDs, GQDs irradiated with gamma rays and GQDs doped with N and N, S atoms are produced using a simple, green approach. By using different techniques (AFM, HR-TEM, SEM-EDS, FTIR, XRD, PL and UV–Vis) we investigated structural and optical properties of the new types of GQDs. We showed that GQDs functionalized with thiourea (GQDs-TU) completely lost the ability to produce singlet oxygen (1O2) upon photoexcitation while functionalization with urea (GQDs-U) improves the capability of GQDs to produce 1O2 upon the same conditions. Thus, presented GQDs modification with urea seems like a promising approach for the production of the efficient photosensitizer. On the opposite, GQDs-TU are efficient [rad]OH quencher. Due to high singlet oxygen production and low cytotoxicity below 100 μg/mL against HeLa cells, GQDs-U is a good candidate as an agent in photodynamic therapy at this concentration. © 2019",
journal = "Materials Science and Engineering: C",
title = "Graphene quantum dots as singlet oxygen producer or radical quencher - The matter of functionalization with urea/thiourea",
volume = "109",
pages = "110539",
doi = "10.1016/j.msec.2019.110539"
}

Jovanović, S. P., Syrgiannis, Z., Budimir, M., Milivojević, D., Jovanović, D. J., Pavlović, V. B., Papan, J., Bartenwerfer, M., Mojsin, M., Stevanović, M. J.,& Todorović-Marković, B.. (2020). Graphene quantum dots as singlet oxygen producer or radical quencher - The matter of functionalization with urea/thiourea. in Materials Science and Engineering: C, 109, 110539.
https://doi.org/10.1016/j.msec.2019.110539

Jovanović SP, Syrgiannis Z, Budimir M, Milivojević D, Jovanović DJ, Pavlović VB, Papan J, Bartenwerfer M, Mojsin M, Stevanović MJ, Todorović-Marković B. Graphene quantum dots as singlet oxygen producer or radical quencher - The matter of functionalization with urea/thiourea. in Materials Science and Engineering: C. 2020;109:110539.
doi:10.1016/j.msec.2019.110539 .

Jovanović, Svetlana P., Syrgiannis, Zois, Budimir, Milica, Milivojević, Dušan, Jovanović, Dragana J., Pavlović, Vladimir B., Papan, Jelena, Bartenwerfer, Malte, Mojsin, Marija, Stevanović, Milena J., Todorović-Marković, Biljana, "Graphene quantum dots as singlet oxygen producer or radical quencher - The matter of functionalization with urea/thiourea" in Materials Science and Engineering: C, 109 (2020):110539,
https://doi.org/10.1016/j.msec.2019.110539 . .

TY  - JOUR
AU  - Jovanović, Svetlana P.
AU  - Marković, Zoran M.
AU  - Syrgiannis, Zois
AU  - Dramićanin, Miroslav
AU  - Arcudi, Francesca
AU  - La Parola, Valeria
AU  - Budimir, Milica
AU  - Todorović-Marković, Biljana
PY  - 2017
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/1622
AB  - Different approaches for enhancement of the graphene quantum dots (GQDs) photoluminescence have been developed lately. We report modified electrochemical procedure for GQDs synthesis. Graphitic rods were thermal annealing at 1700 degrees C in vacuum and used for electrochemical quantum dots synthesis. We found that the modified GQDs (GQDs-1700) consist of two while in the structure of pristine (p-GQDs) three graphene layers are measured. The main structural difference between GQDs is the increased structural disorder, caused by a higher amount of the oxygen containing functional groups in the structure of GQDs-1700. The photoluminescence of GQDs-1700 is 4 times more intense, red shifted and with doubled Quantum Yield compared to p-GQDs. In addition, the changes in electrochemical behavior of GQDs are observed: the higher capacitance was noticed if GQDs posses more reducible functional groups, such as peroxyl, aldehyde and epoxy groups while increase in keto functional groups leads to the lower capacitance. (C) 2017 Elsevier Ltd. All rights reserved.
T2  - Materials Research Bulletin
T1  - Enhancing photoluminescence of graphene quantum dots by thermal annealing of the graphite precursor
VL  - 93
SP  - 183
EP  - 193
DO  - 10.1016/j.materresbull.2017.04.052
ER  - 

@article{
author = "Jovanović, Svetlana P. and Marković, Zoran M. and Syrgiannis, Zois and Dramićanin, Miroslav and Arcudi, Francesca and La Parola, Valeria and Budimir, Milica and Todorović-Marković, Biljana",
year = "2017",
abstract = "Different approaches for enhancement of the graphene quantum dots (GQDs) photoluminescence have been developed lately. We report modified electrochemical procedure for GQDs synthesis. Graphitic rods were thermal annealing at 1700 degrees C in vacuum and used for electrochemical quantum dots synthesis. We found that the modified GQDs (GQDs-1700) consist of two while in the structure of pristine (p-GQDs) three graphene layers are measured. The main structural difference between GQDs is the increased structural disorder, caused by a higher amount of the oxygen containing functional groups in the structure of GQDs-1700. The photoluminescence of GQDs-1700 is 4 times more intense, red shifted and with doubled Quantum Yield compared to p-GQDs. In addition, the changes in electrochemical behavior of GQDs are observed: the higher capacitance was noticed if GQDs posses more reducible functional groups, such as peroxyl, aldehyde and epoxy groups while increase in keto functional groups leads to the lower capacitance. (C) 2017 Elsevier Ltd. All rights reserved.",
journal = "Materials Research Bulletin",
title = "Enhancing photoluminescence of graphene quantum dots by thermal annealing of the graphite precursor",
volume = "93",
pages = "183-193",
doi = "10.1016/j.materresbull.2017.04.052"
}

Jovanović, S. P., Marković, Z. M., Syrgiannis, Z., Dramićanin, M., Arcudi, F., La Parola, V., Budimir, M.,& Todorović-Marković, B.. (2017). Enhancing photoluminescence of graphene quantum dots by thermal annealing of the graphite precursor. in Materials Research Bulletin, 93, 183-193.
https://doi.org/10.1016/j.materresbull.2017.04.052

Jovanović SP, Marković ZM, Syrgiannis Z, Dramićanin M, Arcudi F, La Parola V, Budimir M, Todorović-Marković B. Enhancing photoluminescence of graphene quantum dots by thermal annealing of the graphite precursor. in Materials Research Bulletin. 2017;93:183-193.
doi:10.1016/j.materresbull.2017.04.052 .

Jovanović, Svetlana P., Marković, Zoran M., Syrgiannis, Zois, Dramićanin, Miroslav, Arcudi, Francesca, La Parola, Valeria, Budimir, Milica, Todorović-Marković, Biljana, "Enhancing photoluminescence of graphene quantum dots by thermal annealing of the graphite precursor" in Materials Research Bulletin, 93 (2017):183-193,
https://doi.org/10.1016/j.materresbull.2017.04.052 . .

TY  - JOUR
AU  - Jovanović, Svetlana P.
AU  - Syrgiannis, Zois
AU  - Marković, Zoran M.
AU  - Bonasera, Aurelio
AU  - Kepić, Dejan P.
AU  - Budimir, Milica
AU  - Milivojević, Dušan
AU  - Spasojević, Vuk D.
AU  - Dramićanin, Miroslav
AU  - Pavlović, Vladimir B.
AU  - Todorović-Marković, Biljana
PY  - 2015
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/839
AB  - Herein, the ability of gamma irradiation to enhance the photoluminescence properties of graphene quantum dots (GQDs) was investigated. Different doses of gamma-irradiation were used on GQDs to examine the way in which their structure and optical properties can be affected. The photoluminescence quantum yield was increased six times for the GQDs irradiated with high doses compared to the nonirradiated material. Both photoluminescence lifetime and values of optical band gap were increased with the dose of applied gamma irradiation. In addition, the exploitation of the gamma-irradiated GQDs as photosensitizers was examined by monitoring the production of singlet oxygen under UV illumination. The main outcome was that the GQDs irradiated at lower doses act as better photoproducers than the ones irradiated at higher doses. These results corroborate that the structural changes caused by gamma irradiation have a direct impact on GQD ability to produce singlet oxygen and their photostability under prolonged UV illumination. This makes low-dose irradiated GQDs promising candidates for photodynamic therapy.
PB  - American Chemical Society
T2  - ACS Applied Materials and Interfaces
T1  - Modification of Structural and Luminescence Properties of Graphene Quantum Dots by Gamma Irradiation and Their Application in a Photodynamic Therapy
VL  - 7
IS  - 46
SP  - 25865
EP  - 25874
DO  - 10.1021/acsami.5b08226
ER  - 

@article{
author = "Jovanović, Svetlana P. and Syrgiannis, Zois and Marković, Zoran M. and Bonasera, Aurelio and Kepić, Dejan P. and Budimir, Milica and Milivojević, Dušan and Spasojević, Vuk D. and Dramićanin, Miroslav and Pavlović, Vladimir B. and Todorović-Marković, Biljana",
year = "2015",
abstract = "Herein, the ability of gamma irradiation to enhance the photoluminescence properties of graphene quantum dots (GQDs) was investigated. Different doses of gamma-irradiation were used on GQDs to examine the way in which their structure and optical properties can be affected. The photoluminescence quantum yield was increased six times for the GQDs irradiated with high doses compared to the nonirradiated material. Both photoluminescence lifetime and values of optical band gap were increased with the dose of applied gamma irradiation. In addition, the exploitation of the gamma-irradiated GQDs as photosensitizers was examined by monitoring the production of singlet oxygen under UV illumination. The main outcome was that the GQDs irradiated at lower doses act as better photoproducers than the ones irradiated at higher doses. These results corroborate that the structural changes caused by gamma irradiation have a direct impact on GQD ability to produce singlet oxygen and their photostability under prolonged UV illumination. This makes low-dose irradiated GQDs promising candidates for photodynamic therapy.",
publisher = "American Chemical Society",
journal = "ACS Applied Materials and Interfaces",
title = "Modification of Structural and Luminescence Properties of Graphene Quantum Dots by Gamma Irradiation and Their Application in a Photodynamic Therapy",
volume = "7",
number = "46",
pages = "25865-25874",
doi = "10.1021/acsami.5b08226"
}

Jovanović, S. P., Syrgiannis, Z., Marković, Z. M., Bonasera, A., Kepić, D. P., Budimir, M., Milivojević, D., Spasojević, V. D., Dramićanin, M., Pavlović, V. B.,& Todorović-Marković, B.. (2015). Modification of Structural and Luminescence Properties of Graphene Quantum Dots by Gamma Irradiation and Their Application in a Photodynamic Therapy. in ACS Applied Materials and Interfaces
American Chemical Society., 7(46), 25865-25874.
https://doi.org/10.1021/acsami.5b08226

Jovanović SP, Syrgiannis Z, Marković ZM, Bonasera A, Kepić DP, Budimir M, Milivojević D, Spasojević VD, Dramićanin M, Pavlović VB, Todorović-Marković B. Modification of Structural and Luminescence Properties of Graphene Quantum Dots by Gamma Irradiation and Their Application in a Photodynamic Therapy. in ACS Applied Materials and Interfaces. 2015;7(46):25865-25874.
doi:10.1021/acsami.5b08226 .

Jovanović, Svetlana P., Syrgiannis, Zois, Marković, Zoran M., Bonasera, Aurelio, Kepić, Dejan P., Budimir, Milica, Milivojević, Dušan, Spasojević, Vuk D., Dramićanin, Miroslav, Pavlović, Vladimir B., Todorović-Marković, Biljana, "Modification of Structural and Luminescence Properties of Graphene Quantum Dots by Gamma Irradiation and Their Application in a Photodynamic Therapy" in ACS Applied Materials and Interfaces, 7, no. 46 (2015):25865-25874,
https://doi.org/10.1021/acsami.5b08226 . .

TY  - JOUR
AU  - Prekodravac, Jovana
AU  - Marković, Zoran M.
AU  - Jovanović, Svetlana P.
AU  - Budimir, Milica
AU  - Peruško, Davor
AU  - Holclajtner-Antunović, Ivanka D.
AU  - Pavlović, Vladimir B.
AU  - Syrgiannis, Zois
AU  - Bonasera, Aurelio
AU  - Todorović-Marković, Biljana
PY  - 2015
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/797
AB  - In this paper, we performed synthesis of graphene thin films by rapid thermal annealing (RTA) of thin nickel copper (Ni/Cu) layers deposited on spectroscopic graphite as a carbon source. Furthermore, we investigated the effect of annealing temperature and annealing time on formation and quality of synthesized graphene films. Raman spectroscopy study showed that annealing at lower temperatures results in formation of monolayer graphene films, while annealing at higher temperatures results in formation of multilayer graphene films. We used Raman mapping to determine the distribution of graphene sheets. Surface morphology of graphene thin films was investigated by atomic force microscopy and scanning electron microscopy with EDS probe. (C) 2015 Elsevier B.V. All rights reserved.
T2  - Synthetic Metals
T1  - The effect of annealing temperature and time on synthesis of graphene thin films by rapid thermal annealing
VL  - 209
SP  - 461
EP  - 467
DO  - 10.1016/j.synthmet.2015.08.015
ER  - 

@article{
author = "Prekodravac, Jovana and Marković, Zoran M. and Jovanović, Svetlana P. and Budimir, Milica and Peruško, Davor and Holclajtner-Antunović, Ivanka D. and Pavlović, Vladimir B. and Syrgiannis, Zois and Bonasera, Aurelio and Todorović-Marković, Biljana",
year = "2015",
abstract = "In this paper, we performed synthesis of graphene thin films by rapid thermal annealing (RTA) of thin nickel copper (Ni/Cu) layers deposited on spectroscopic graphite as a carbon source. Furthermore, we investigated the effect of annealing temperature and annealing time on formation and quality of synthesized graphene films. Raman spectroscopy study showed that annealing at lower temperatures results in formation of monolayer graphene films, while annealing at higher temperatures results in formation of multilayer graphene films. We used Raman mapping to determine the distribution of graphene sheets. Surface morphology of graphene thin films was investigated by atomic force microscopy and scanning electron microscopy with EDS probe. (C) 2015 Elsevier B.V. All rights reserved.",
journal = "Synthetic Metals",
title = "The effect of annealing temperature and time on synthesis of graphene thin films by rapid thermal annealing",
volume = "209",
pages = "461-467",
doi = "10.1016/j.synthmet.2015.08.015"
}

Prekodravac, J., Marković, Z. M., Jovanović, S. P., Budimir, M., Peruško, D., Holclajtner-Antunović, I. D., Pavlović, V. B., Syrgiannis, Z., Bonasera, A.,& Todorović-Marković, B.. (2015). The effect of annealing temperature and time on synthesis of graphene thin films by rapid thermal annealing. in Synthetic Metals, 209, 461-467.
https://doi.org/10.1016/j.synthmet.2015.08.015

Prekodravac J, Marković ZM, Jovanović SP, Budimir M, Peruško D, Holclajtner-Antunović ID, Pavlović VB, Syrgiannis Z, Bonasera A, Todorović-Marković B. The effect of annealing temperature and time on synthesis of graphene thin films by rapid thermal annealing. in Synthetic Metals. 2015;209:461-467.
doi:10.1016/j.synthmet.2015.08.015 .

Prekodravac, Jovana, Marković, Zoran M., Jovanović, Svetlana P., Budimir, Milica, Peruško, Davor, Holclajtner-Antunović, Ivanka D., Pavlović, Vladimir B., Syrgiannis, Zois, Bonasera, Aurelio, Todorović-Marković, Biljana, "The effect of annealing temperature and time on synthesis of graphene thin films by rapid thermal annealing" in Synthetic Metals, 209 (2015):461-467,
https://doi.org/10.1016/j.synthmet.2015.08.015 . .

TY  - JOUR
AU  - Jovanović, Svetlana P.
AU  - Marković, Zoran M.
AU  - Kleut, Duška
AU  - Dramićanin, Miroslav
AU  - Holclajtner-Antunović, Ivanka D.
AU  - Milosavljević, Momir
AU  - La Parola, Valeria
AU  - Syrgiannis, Zois
AU  - Todorović-Marković, Biljana
PY  - 2014
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/6085
AB  - Single wall carbon nanotubes (SWCNTs) were exposed to gamma irradiation in oxidative (H2O, NH4OH) and reductive (H2O and NH4OH both mixed with isopropyl alcohol) media. The structure has been investigated with microscopic (atomic force and transmission electron microscopy), spectroscopic (Raman, X-ray photoelectron, and FTIR spectroscopy) techniques, and by thermogravimetric analysis. Reductive media offer the possibility for green chemistry reduction of SWCNTs: after gamma irradiation, SWCNTs lose C-O bonds. Furthermore, irradiation in these media increases the fraction of sp(2) hybridized carbon atoms in structure of SWCNTs and prevents their amorphization. The presence of isopropyl alcohol in reductive media contributed to the preservation of structures unity. On the other hand, the most effective procedure is the one that occurs in oxidative media and yields in debundled, cut, and annihilated carbon nanotubes. The smaller diameter and the metallic ones are the most affected.
T2  - Journal of Physical Chemistry. C
T1  - Structural Analysis of Single Wall Carbon Nanotubes Exposed to Oxidation and Reduction Conditions in the Course of Gamma Irradiation
VL  - 118
IS  - 29
SP  - 16147
EP  - 16155
DO  - 10.1021/jp502685n
ER  - 

@article{
author = "Jovanović, Svetlana P. and Marković, Zoran M. and Kleut, Duška and Dramićanin, Miroslav and Holclajtner-Antunović, Ivanka D. and Milosavljević, Momir and La Parola, Valeria and Syrgiannis, Zois and Todorović-Marković, Biljana",
year = "2014",
abstract = "Single wall carbon nanotubes (SWCNTs) were exposed to gamma irradiation in oxidative (H2O, NH4OH) and reductive (H2O and NH4OH both mixed with isopropyl alcohol) media. The structure has been investigated with microscopic (atomic force and transmission electron microscopy), spectroscopic (Raman, X-ray photoelectron, and FTIR spectroscopy) techniques, and by thermogravimetric analysis. Reductive media offer the possibility for green chemistry reduction of SWCNTs: after gamma irradiation, SWCNTs lose C-O bonds. Furthermore, irradiation in these media increases the fraction of sp(2) hybridized carbon atoms in structure of SWCNTs and prevents their amorphization. The presence of isopropyl alcohol in reductive media contributed to the preservation of structures unity. On the other hand, the most effective procedure is the one that occurs in oxidative media and yields in debundled, cut, and annihilated carbon nanotubes. The smaller diameter and the metallic ones are the most affected.",
journal = "Journal of Physical Chemistry. C",
title = "Structural Analysis of Single Wall Carbon Nanotubes Exposed to Oxidation and Reduction Conditions in the Course of Gamma Irradiation",
volume = "118",
number = "29",
pages = "16147-16155",
doi = "10.1021/jp502685n"
}

Jovanović, S. P., Marković, Z. M., Kleut, D., Dramićanin, M., Holclajtner-Antunović, I. D., Milosavljević, M., La Parola, V., Syrgiannis, Z.,& Todorović-Marković, B.. (2014). Structural Analysis of Single Wall Carbon Nanotubes Exposed to Oxidation and Reduction Conditions in the Course of Gamma Irradiation. in Journal of Physical Chemistry. C, 118(29), 16147-16155.
https://doi.org/10.1021/jp502685n

Jovanović SP, Marković ZM, Kleut D, Dramićanin M, Holclajtner-Antunović ID, Milosavljević M, La Parola V, Syrgiannis Z, Todorović-Marković B. Structural Analysis of Single Wall Carbon Nanotubes Exposed to Oxidation and Reduction Conditions in the Course of Gamma Irradiation. in Journal of Physical Chemistry. C. 2014;118(29):16147-16155.
doi:10.1021/jp502685n .

Jovanović, Svetlana P., Marković, Zoran M., Kleut, Duška, Dramićanin, Miroslav, Holclajtner-Antunović, Ivanka D., Milosavljević, Momir, La Parola, Valeria, Syrgiannis, Zois, Todorović-Marković, Biljana, "Structural Analysis of Single Wall Carbon Nanotubes Exposed to Oxidation and Reduction Conditions in the Course of Gamma Irradiation" in Journal of Physical Chemistry. C, 118, no. 29 (2014):16147-16155,
https://doi.org/10.1021/jp502685n . .