Simultaneous electrochemical determination of uric acid and hypoxanthine at a TiO₂/graphene quantum dot-modified electrode

• Vu Ngoc Hoang,
• Dang Thi Ngoc Hoa,
• Nguyen Quang Man,
• Le Vu Truong Son,
• Le Van Thanh Son,
• Vo Thang Nguyen,
• Le Thi Hong Phong,
• Ly Hoang Diem,
• Kieu Chan Ly,
• Ho Sy Thang and
• Dinh Quang Khieu

Beilstein J. Nanotechnol. 2024, 15, 719–732, doi:10.3762/bjnano.15.60

• , Hue University, Vietnam The University of Danang, University of Science and Education, Vietnam Institute of Materials Science, Vietnam Academy of Science and Technology, Vietnam Kien Giang University, Vietnam Dong Thap University, Vietnam 10.3762/bjnano.15.60 Abstract A TiO2/graphene quantum dots

• urine samples with acceptable recovery rates. Keywords: graphene quantum dots; hypoxanthine; peroxo titanium complexes; uric acid; Introduction Uric acid (7,9-dihydro-1H-purine-2,6,8(3H)-trione, URI) is the primary final product of the purine metabolism in humans. High concentrations of URI in serum

• properties. Graphene quantum dots (GQDs) are zero-dimensional graphene derivatives consisting of one to few layers of graphene sheets with a size of less than 20 nm in width [11]. The missing bandgap results in an absence of luminescence in pristine graphene. However, a bandgap can be generated in GQDs

Photocatalytic degradation of methylene blue under visible light by cobalt ferrite nanoparticles/graphene quantum dots

• Vo Chau Ngoc Anh,
• Le Thi Thanh Nhi,
• Le Thi Kim Dung,
• Dang Thi Ngoc Hoa,
• Nguyen Truong Son,
• Nguyen Thi Thao Uyen,
• Nguyen Ngoc Uyen Thu,
• Le Van Thanh Son,
• Le Trung Hieu,
• Tran Ngoc Tuyen and
• Dinh Quang Khieu

Beilstein J. Nanotechnol. 2024, 15, 475–489, doi:10.3762/bjnano.15.43

• synthesize cobalt ferrite nanoparticles/graphene quantum dots (CF/GQDs). The material was prepared from a homogeneous mixture of iron nitrate, cobalt nitrate, and starch at 140, 180 and 200 °C in a 24 h thermal hydrolysis process. The obtained materials were characterised by using X-ray diffraction, scanning

• graphene quantum dots formed directly at 200 °C. Stacking GQDs sheets onto the CF nanoparticles resulted in CF/GQDs nanoparticles. The nanocomposite exhibits satisfactory fluorescent and superparamagnetic properties, which are vital for catalytic applications. The CF/GQDs catalyse significantly the

• degradation and other dyes. Keywords: cobalt ferrite; graphene quantum dots; methylene blue; Introduction Graphene quantum dots (GQDs) have unique properties, including photoluminescence, biocompatibility, slight chemical toxicity, inertness, and excellent photostability [1][2]. Graphene quantum dots

A graphene quantum dots–glassy carbon electrode-based electrochemical sensor for monitoring malathion

• Sanju Tanwar,
• Aditi Sharma and
• Dhirendra Mathur

Beilstein J. Nanotechnol. 2023, 14, 701–710, doi:10.3762/bjnano.14.56

• Sanju Tanwar Aditi Sharma Dhirendra Mathur Centre of Nanotechnology, Rajasthan Technical University, Kota, Rajasthan, India Materials Research Centre, Malaviya National Institute of Technology, Jaipur, Rajasthan, India 10.3762/bjnano.14.56 Abstract Graphene quantum dots (GQDs) were made via a

• spectroscopy; electrochemical sensor; graphene quantum dots; malathion; Introduction Global population growth makes food production more challenging, and pesticides are therefore used in agriculture in greater quantities than in the past to maintain and increase crop yields [1][2]. Pesticides containing

• lowers the detection limit [18]. In an effort to combine the properties of carbon dots and graphene, graphene quantum dots (GQDs) with a size smaller than 100 nm and only a few layers of graphene (3 to 10 layers) have been developed as a new class of carbon nanomaterials [19]. Scientists have explored

Structural, optical, and bioimaging characterization of carbon quantum dots solvothermally synthesized from o-phenylenediamine

• Zoran M. Marković,
• Milica D. Budimir,
• Martin Danko,
• Dušan D. Milivojević,
• Pavel Kubat,
• Danica Z. Zmejkoski,
• Vladimir B. Pavlović,
• Marija M. Mojsin,
• Milena J. Stevanović and
• Biljana M. Todorović Marković

Beilstein J. Nanotechnol. 2023, 14, 165–174, doi:10.3762/bjnano.14.17

• shows that the absorption of DPBF solution in both vials is nearly identical. This means that the CQDs/PU sample does not produce singlet oxygen, which confirms the previous results obtained by EPR and luminescence at 1270 nm. Ge et al. reported earlier that graphene quantum dots generate singlet oxygen

• through energy transfer to molecular oxygen [21]. Chong et al. claimed that superoxide anions are involved in the generation of singlet oxygen, implying that electron transfer is an intermediate step for the generation of singlet oxygen by photoexcited graphene quantum dots [20]. In nitrogen-doped

Recent trends in Bi-based nanomaterials: challenges, fabrication, enhancement techniques, and environmental applications

• Vishal Dutta,
• Ankush Chauhan,
• Ritesh Verma,
• C. Gopalkrishnan and
• Van-Huy Nguyen

Beilstein J. Nanotechnol. 2022, 13, 1316–1336, doi:10.3762/bjnano.13.109

Recent advances in green carbon dots (2015–2022): synthesis, metal ion sensing, and biological applications

• Aisha Kanwal,
• Naheed Bibi,
• Sajjad Hyder,
• Arif Muhammad,
• Hao Ren,
• Jiangtao Liu and
• Zhongli Lei

Beilstein J. Nanotechnol. 2022, 13, 1068–1107, doi:10.3762/bjnano.13.93

• materials, are summarized in Table 4. Natural polymer-based CDs Numerous natural polymers, including proteins and polysaccharides, have been used to obtain CDs (Table 5). Chen and co-workers used starch as a source to synthesize graphene quantum dots (CDs) via a one-pot hydrothermal method. They also

• the recombination of trapped excitons causes the redshifted emission. Liu et al. reported the synthesis of highly photoluminescent CDs, which were then further separated into yellow emitting crystalline graphene quantum dots and green emitting amorphous carbon nanodots using a silica gel column. Even

Spindle-like MIL101(Fe) decorated with Bi₂O₃ nanoparticles for enhanced degradation of chlortetracycline under visible-light irradiation

• Chen-chen Hao,
• Fang-yan Chen,
• Kun Bian,
• Yu-bin Tang and
• Wei-long Shi

Beilstein J. Nanotechnol. 2022, 13, 1038–1050, doi:10.3762/bjnano.13.91

• an octahedron shape, and its size increases compared with that of pristine MIL101(Fe). In previous reports, graphene quantum dots changed the balance of organic ligands, which led to the change of MIL101(Fe) size [38]. In addition, Liao et al. reported that morphology or size of MOFs are dependent on

Tin dioxide nanomaterial-based photocatalysts for nitrogen oxide oxidation: a review

• Viet Van Pham,
• Hong-Huy Tran,
• Thao Kim Truong and
• Thi Minh Cao

Beilstein J. Nanotechnol. 2022, 13, 96–113, doi:10.3762/bjnano.13.7

• contributed to improving the charge separation, significantly reducing indoor NO under visible light irradiation. The optimized composite removed 57% of the initial NO while generating a negligible amount of NO2. In addition, this work found that the insertion of graphene quantum dots did not induce any

• . (c) Transient photocurrent response and (d) EIS curves of SnO2 and SnO2/GQDs (1%) under visible light illumination and in darkness. Figure 13 was reprinted from [36], Applied Surface Science, vol. 448, by Xie, Y.; Yu, S.; Zhong, Y.; Zhang, Q.; Zhou, Y. “SnO2/graphene quantum dots composited

A review on the biological effects of nanomaterials on silkworm (Bombyx mori)

• Sandra Senyo Fometu,
• Guohua Wu,
• Lin Ma and
• Joan Shine Davids

Beilstein J. Nanotechnol. 2021, 12, 190–202, doi:10.3762/bjnano.12.15

• graphene quantum dots on its motor nervous system. The locomotion of the nematodes deteriorated following the exposure to these nanomaterials with damages in the dopaminergic and glutamatergic neurons [46]. Fast embryonic development outside the parent zebrafish is an attractive feature that allows for the

• the values of tensile strength and strain obtained for natural silk fiber (control), respectively. Ma et al. [169] evaluated the effect of vascular injection of graphene quantum dots (GQDs) in silkworm on the mechanical properties of the silk. GQDs are known for their outstanding mechanical properties

Synthesis and acetone sensing properties of ZnFe₂O₄/rGO gas sensors

• Kaidi Wu,
• Yifan Luo,
• Ying Li and
• Chao Zhang

Beilstein J. Nanotechnol. 2019, 10, 2516–2526, doi:10.3762/bjnano.10.242

• characteristics and the gas sensing properties. Furthermore, 0.125 wt % graphene-ZnFe2O4 was prepared by a solvothermal method, and the corresponding gas sensor exhibited a fine response to 10–100 ppm acetone at 275 °C [31]. A hybrid sensor made of ZnFe2O4/graphene quantum dots showed a fine sensing response to

Green synthesis of fluorescent carbon dots from spices for in vitro imaging and tumour cell growth inhibition

• Nagamalai Vasimalai,
• Vânia Vilas-Boas,
• Juan Gallo,
• María de Fátima Cerqueira,
• Mario Menéndez-Miranda,
• José Manuel Costa-Fernández,
• Lorena Diéguez,
• Begoña Espiña and
• María Teresa Fernández-Argüelles

Beilstein J. Nanotechnol. 2018, 9, 530–544, doi:10.3762/bjnano.9.51

• graphene quantum dots (GQDs) are emerging as new alternatives due to their excellent properties, including high photoluminescence, low photobleaching, high biocompatibility and low toxicity. C-dots avoid the use of heavy metals present in semiconductor quantum dots, which have raised important health and

Sugarcane juice derived carbon dot–graphitic carbon nitride composites for bisphenol A degradation under sunlight irradiation

• Lan Ching Sim,
• Jing Lin Wong,
• Chen Hong Hak,
• Jun Yan Tai,
• Kah Hon Leong and
• Pichiah Saravanan

Beilstein J. Nanotechnol. 2018, 9, 353–363, doi:10.3762/bjnano.9.35

• consistent with previous reports [61]. A recent study by Wen and co-workers suggested that most of the CDs and graphene quantum dots (GQDs) do not have detectable upconversion fluorescence. The frequently cited UCPL properties could originate from the normal fluorescence excited by the leaking component from

Co-reductive fabrication of carbon nanodots with high quantum yield for bioimaging of bacteria

• Jiajun Wang,
• Xia Liu,
• Gesmi Milcovich,
• Tzu-Yu Chen,
• Edel Durack,
• Sarah Mallen,
• Yongming Ruan,
• Xuexiang Weng and
• Sarah P. Hudson

Beilstein J. Nanotechnol. 2018, 9, 137–145, doi:10.3762/bjnano.9.16

• 2% to 24% following reduction with sodium borohydride (NaBH4). The same results were confirmed by Shen and Tian's group [15][16]. It was also reported that the fluorescence intensity of graphene quantum dots reduced by hydrazine hydrate (N2H4) can be enhanced to more than two times that of the

• pristine graphene quantum dots [17]. However, this reduction pathway is based on a two-step procedure: firstly, a synthesis and collection of bare C-dots, then a reduction of C-dots to enhance their QY. The above procedure is often time consuming, poses difficulty in achieving a final pure sample, and

• ][20]. Qu et al. obtained graphene quantum dots with a quantum yield of 78% and 71% using citric acid and urea or citric acid and thiourea as the precursors, respectively. They demonstrated that N or N/S doping led to the high QY of the C-dots. Zeng et al. prepared C-dots with a relatively high QY

Facile fabrication of luminescent organic dots by thermolysis of citric acid in urea melt, and their use for cell staining and polyelectrolyte microcapsule labelling

• Nadezhda M. Zholobak,
• Anton L. Popov,
• Alexander B. Shcherbakov,
• Nelly R. Popova,
• Mykhailo M. Guzyk,
• Valeriy P. Antonovich,
• Alla V. Yegorova,
• Yuliya V. Scrypynets,
• Inna I. Leonenko,
• Alexander Ye. Baranchikov and
• Vladimir K. Ivanov

Beilstein J. Nanotechnol. 2016, 7, 1905–1917, doi:10.3762/bjnano.7.182

• nitric acid oxidation of carbon soot reduced the viability of HepG2 cells by 20%, at concentrations higher than 100 μg/mL [49]. The graphene quantum dots prepared with graphene oxide as starting material were markedly toxic for MCF-7 and MGC-803 (human gastric cancer) cells at concentrations higher than

Synthesis of hydrophobic photoluminescent carbon nanodots by using L-tyrosine and citric acid through a thermal oxidation route

• Venkatesh Gude

Beilstein J. Nanotechnol. 2014, 5, 1513–1522, doi:10.3762/bjnano.5.164

• as heterogeneous graphene quantum dots (GQDs) [15]. Many research groups developed synthetic routes to obtain CNDs without using surface passivating agents, by using natural resources like candle soot [6], orange juice [7], banana juice [16], ground soybeans [17], waste paper [18], and paper ash [19

• structural defects [2][5][15][20]. Recently, Cushing et al. reported that the origin of excitation wavelength dependent emission, the continuous red shift and the broadening of bands is due to a “giant red-edge effect” of heterogeneous graphene quantum dots. The giant red-edge effect appears because the

Photocatalysis

• Rong Xu

Beilstein J. Nanotechnol. 2014, 5, 1071–1072, doi:10.3762/bjnano.5.119

• and morphological tuning, in particular for hybrid materials systems such as Ag–ZnO, VTi/MCM-41, are important toward achieving higher solar energy conversion efficiencies. In a couple of reports, materials alternative to conventional metal oxides, for example, reduced graphene oxide, graphene quantum

• dots integrated with TiO2 nanotube arrays, and carbon nitride, have been explored to construct photocatalysts with enhanced performances. On the other hand, molecular catalysts have an advantage in design flexibility and structural tunability. A contribution based on the investigation of molecular

A visible-light-driven composite photocatalyst of TiO₂ nanotube arrays and graphene quantum dots

• Donald K. L. Chan,
• Po Ling Cheung and
• Jimmy C. Yu

Beilstein J. Nanotechnol. 2014, 5, 689–695, doi:10.3762/bjnano.5.81

• incorporation of graphene quantum dots could extend the photo-response of the nanotubes to the visible-light range. Graphene quantum dot-sensitized TiO2 nanotube arrays were synthesized by covalently coupling these two materials. The product was characterized by Fourier-transform infrared spectrometry (FTIR

• light irradiation. Keywords: anodic oxidation; graphene quantum dots; photocatalyst; photodegradation; TiO2 nanotube arrays; Introduction Semiconductor-mediated photocatalysis is a promising technique for the conversion of solar energy as well as degradation of organic pollutants in air and water [1

• , graphene sheets are usually micrometer-sized and they can hardly be introduced into efficient nano-sized photocatalysts on a solid support, for example, TNAs. Zero-dimensional graphene quantum dots (GQDs) are defined as few-layered graphene with lateral dimensions smaller than 100 nm [28]. Due to quantum

Advances in nanomaterials

• Herbert Gleiter,
• Horst Hahn and
• Thomas Schimmel

Beilstein J. Nanotechnol. 2013, 4, 805–806, doi:10.3762/bjnano.4.91

• these contributions is found in this Thematic Series in the form of original research articles reflecting recent advances in nanomaterials. The articles in this Thematic Series highlight recent developments, from nanoporous polymers to graphene quantum dots, from concepts for designing magnetic

Magnetic anisotropy of graphene quantum dots decorated with a ruthenium adatom

• Igor Beljakov,
• Velimir Meded,
• Franz Symalla,
• Karin Fink,
• Sam Shallcross and
• Wolfgang Wenzel

Beilstein J. Nanotechnol. 2013, 4, 441–445, doi:10.3762/bjnano.4.51

• motivate our present study of the MAE of Ru adatoms on a graphene flake. Methods As the system of choice, triangular hydrogen-saturated graphene flakes (or graphene quantum dots) were investigated, comprising 90 and 97 carbon atoms for two different edge types, armchair and zigzag (AGQD and ZGQD

• reported by Lieb [27]. As we shall subsequently see, this difference in the magnetic state of the pristine graphene quantum dots leads to a qualitatively different behaviour of the magnetic anisotropy of the absorbed Ru atom. Before considering in detail the magnetic state of the Ru adatom, however, we

• of the flake. Conclusion Using first-principles DFT methods we have investigated the magnetic properties of Ru adatoms on two types of graphene flakes: the armchair (AGQD) and zigzag (ZGQD) edged triangular graphene quantum dots. The geometry of these flakes is such that each has only one specific

Graphite, graphene on SiC, and graphene nanoribbons: Calculated images with a numerical FM-AFM

• Fabien Castanié,
• Laurent Nony,
• Sébastien Gauthier and
• Xavier Bouju

Beilstein J. Nanotechnol. 2012, 3, 301–311, doi:10.3762/bjnano.3.34

• were also observed experimentally by STM on GNR or on graphene quantum dots [79][114][115]. A calculated FM-AFM image acquired with the n-AFM in the frozen-atoms regime is shown in Figure 4a. Here, the setpoint is Hset = 3.8 Å and the Δf corrugation is 81.7 Hz. At this setpoint, it is not possible to