Presence Of Graphene Quantum Dots Research Articles

Zinc oxide doped with graphene quantum dots as improved electron transport layers for planner perovskite solar cells

Zinc oxide (ZnO), a material with excellent electron mobility and a low-temperature requirement for production, is a promising option for use as an electron transport layer in perovskite solar cells (PSCs). However, it does have the drawback of having a low open-circuit voltage ([Formula: see text]). Herein, to increase the [Formula: see text] parameter of ZnO-based PSCs, graphene quantum dots (GQDs) are incorporated into the ZnO precursor and used as desirable ETL for PSCs. The presence of GQDs in ZnO ETL facilitated photo-electrons at the ETL/perovskite interface by reducing charge transfer resistance in this interface. Compared to the net ZnO-based PSCs, solar cells using GQD-doped ZnO as ETL have better stability, comparable [Formula: see text], higher [Formula: see text], and FF. The best GQD-doped-ZnO ETL-based PSCs recorded the highest power conversion efficiency of 20.23% with [Formula: see text] of 1.130[Formula: see text]V. Meanwhile, the boosted PCE of FAPbI3-based PSCs is achieved due to the improved perovskite crystal quality, the effective defect passivation effect of GQDs at ZnO/FAPbI3 interface, and the increased electrical conductivity of ZnO ETL. In addition, the GQD-doped ETL devices showed higher ambient air stability than the devices with net ZnO ETLs.

Measuring lipid peroxidation in the presence of graphene quantum dots

Measuring lipid peroxidation in the presence of graphene quantum dots

Adsorption and detection tramadol in aqueous solution by fluorescent- magnetic molecularly imprinting polymers

BackgroundThe usage of tramadol (TR) as one of the most common analgesics is expansively growing in the world. Therefore, there is an urgent requirement for a rapid and reliable method for the on-site detection of tramadol in different samples. The elimination half-life of tramadol is about 6 h, and its removal from body is relatively slow. So, it is very critical providing a method for rapid detection of tramadol. MethodsIn this study, three magnetic nanocomposites (Fe3O4, Fe3O4/SiO2, and Fe3O4/SiO2/CMC) and molecularly imprinted polymers (MIPs) based on those in the presence of graphene quantum dots (GQDs) were synthesized and investigated for selective adsorption and detection of TR in aqueous solution. For the characterization of synthesized materials, XRD, FT-IR, SEM, VSM, and the response surface method (RSM) were also employed to optimize and estimate the effective parameters of TR adsorption by these materials. Significant findingsThe results of investigating the absorption ability of nanocomposites showed that the Fe3O4/SiO2/CMC composite has higher absorption ability than the other two nanocomposites. Moreover, Fe3O4/SiO2/CMC has an excellent ability to adsorb of TR with a removal percentage of 97.46 % at pH = 7, initial TR concentration = 15 mg/L, composite dosage = 1.5 g/L, and contact time = 6 min. According to the experimental results, the imprinting factors (IF) of MIP-Fe3O4, MIP-Fe3O4/SiO2, and MIP-Fe3O4/SiO2/CMC are 1.02, 1.72, and 2.19, respectively. Therefore, the MIP-Fe3O4/SiO2/CMC was chosen as a selective sensor, and the sensitivity of its response was investigated. The detection of TR was performed by fluorescence spectroscopy at a concentration range of TR of 0 to 250 µM, and a sensitivity of 3.13 a.u./µM and limit of detection of 2.08 µM were determined. Also, the river water and artificial urine samples (with TR of 10 µM) was detected using MIP-Fe3O4/SiO2/CMC, and the results of the sensor showed a TR concentration of river water is 9.97 µM and artificial urine is 10.456 µM and which is very good and acceptable precision.

In-situ green synthesis of copper tannic acid framework in the presence of graphene quantum dots: Improved colloidal and antibacterial properties

This work reports the preparation of a copper tannic acid MOF (CuTA) and graphene quantum dot (GQD) nanocomposite, GQD/CuTA, by a simple, environmentally friendly, and inexpensive method with exceptionally enhanced antibacterial properties. To end this, GQDs were first fabricated from citric acid using a neoteric, simple and straightforward hydrolysis approach and followed by they effectively anchor MOF nanoparticles (CuTA) by a green hydrothermal in situ synthesizing method. The constructed GQD/CuTA nanomaterials were characterized and validated using XRD, FT-IR, TEM, DLS, UV–vis, and PL techniques. Significant antibacterial activity against E. coli bacteria for both CuTA and GQD/CuTA (0 CFU/mL) and S. aureus bacteria for CuTA and GQD/CuTA (300 and 40 CFU/mL) was observed for the GQD/CuTA nanocomposite. The MTT assay showed good cytocompatibility for the GQD/CuTA nanocomposite against human dermal fibroblast cells (HFF-2). The result suggests that the synthesized GQD/CuTA nanocomposite with improved colloidal and antibacterial properties has the potential to be used as a safe photoluminescent nanoplatform with strong antimicrobial activity.

The synergistic triad of graphene quantum dots, polymer, and ferrites for the photodegradation of dyes in aqueous solution

This work aimed to investigate photocatalytic properties of GQDs@PEG@Mg–ZnFe2O4 nanocomposite, composed of graphene quantum dots (GQDs), polyethylene glycol (PEG), and Mg–ZnFe2O4, for the degradation of methylene blue (MB) and crystal violet (CV). This nanocomposite was synthesized using facile ultrasonics-assisted methodology. XRD analysis confirmed the formation of the spinel structure of the Mg–ZnFe2O4 in the nanocomposite, whereas the presence of GQDs and PEG was confirmed by Fourier transform infrared spectroscopy. Scanning electron microscopy (SEM) revealed a reduction in agglomeration and particle size in the ternary nanocomposite. The GQDs@PEG@Mg–ZnFe2O4 nanocomposite demonstrates a remarkable degradation efficiency of 98 % for CV and MB dyes in the presence of sunlight in 120 min, indicating its potential as an efficient photocatalyst. Vibrating sample magnetometer (VSM) analysis confirmed the superparamagnetic behavior of the GQDs@PEG@Mg–ZnFe2O4 nanocomposite which enables magnetic recovery of the photocatalyst after the degradation process. Overall, this study emphasizes the utilization of an environmentally friendly approach to effectively eliminate organic pollutants from wastewater, addressing a crucial environmental concern.

CuCo2O4 supported graphene quantum dots as a new and promising catalyst for methanol oxidation reaction

Recently, the design of an active electrocatalyst with a unitary structure and high electrocatalytic performance as an efficient and low-cost electrode material has received enormous attention in improving the performance of energy and storage devices. In this study, flower-like CuCo2O4 nanorods are synthesized through the hydrothermal method followed by calcination. Then, CuCo2O4 is hybridized with graphene quantum dots (GQDs) prepared by the pyrolysis method. The structure and morphology of the synthesized electrocatalysts are analyzed by scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, Fourier transform infrared spectroscopy, and X-ray diffraction methods. The electrochemical performance of the prepared materials supported on a glassy carbon electrode is investigated by cyclic voltammetry at different methanol concentrations and various scan rates. Also, chronoamperometry and electrochemical impedance spectroscopy techniques are performed for the evaluation of stability and conductivity. The GQD/CuCo2O4 exhibits a good electrochemical surface area of 19.25 cm2 in 1 M KOH and 4 M methanol. Also, GQD/CuCo2O4 shows a higher current density for methanol oxidation reaction (MOR) than CuCo2O4. The superior electrochemical performance of the GQD/CuCo2O4 can be attributed to the strengthening of the CuCo2O4 nanoparticle structure by a large electrochemically active surface associated with nanoporous morphology in the presence of GQDs. Besides, GQDs enhance the catalyst's performance by increasing electrical conductivity and specific surface area.

The role of graphene quantum dots in mitigating lipid peroxidation.

Lipid peroxidation often underlies apoptosis and mitochondrial dysfunction, which are common pathological phenomena in neurodegenerative and lysosomal storage diseases. Graphene quantum dots (GQDs) have garnered considerable interest as a nanomedicine over the last several years due to their biocompatibility and ability to target cellular disorders associated with disease phenotypes. Recent work with cells containing α-synuclein aggregates (i.e., cells mimicking the onset of Parkinson's disease) has demonstrated that GQDs exhibit mitoprotective behavior. In these studies, GQDs were able to permeate the plasma membrane, inhibit mitochondrial deformation, and restore mitochondrial complex I activity. However, the mechanism by which GQDs interacted with mitochondria was neither examined nor understood. It is known that this type of mitochondrial dysfunction is associated with free radical-induced oxidative lipid damage. Therefore, we hypothesize that the observed mitoprotective properties of GQDs arise from the scavenging of reactive oxidative species that would otherwise interact with mitochondrial membranes. To test this hypothesis, we developed a system to examine lipid peroxidation in synthetic membranes while in the presence of GQDs. Here, we used the fluorescent sensor C11-BODIPY to monitor the kinetics of lipid peroxidation in the presence of hydroxyl free radicals. Comparison of peroxidation rates to first principles kinetic models confirmed that GQDs were indeed scavengers of free radicals. When membranes were incubated with GQDs, the lipid peroxidation rate decreased by 90%. Interestingly, when compared to other renowned antioxidants, such as ascorbic acid and Trolox, GQDs exhibited significantly higher antioxidant efficiency. Ascorbic acid and Trolox required substantially higher concentrations than GQDs to achieve comparable levels of reduction to lipid peroxidation rates. These results warrant further investigation of GQDs as a mitochondrial membrane protection agent.

Sonochimical synthesis, characterization and physicochemical properties of Cu3Mo2O9 graphene-based nanocomposites for antibacterial therapeutic agent with enhanced activity

In this study, Cu3Mo2O9 nanoparticles (NPs) were synthesized by ultrasonic technique as a facile method. The effective parameters on properties of products including: sonication time, capping agent and calcination temperature were changed in order to prepare the desired properties including fine particles with homogeny morphologies. The nanoparticles synthesized in the optimum conditions were utilized to prepare graphene quantum dots-based nanocomposites (Cu3Mo2O9/GQDs NCs). Next, antibacterial activities of the prepared products were studied. According to the results, the antibacterial performance of the nanocomposite was better than pristine nanoparticles. It can be interpreted through two mechanisms that both of them are related to the presence of graphene quantum dots: (a) increasing the production of reactive oxygen species (ROS) and (b) increasing the surface area that increases aggregation of nanoparticles on cell walls of bacteria. According to the results, the minimum inhibitory concentration (MIC) and zone of inhibition of Cu3Mo2O9/GQDs NCs were recorded 156.25 μg/ml and 27 mm against Staphylococcus saprophyticu, respectively. Consequently, the prepared nanocomposite can be identified as a promising antibacterial product.

Electrocatalytic activity of manganese tetra 4-aminophenyl porphyrin in the presence of graphene quantum dots

A manganese tetra 4-aminophenyl porphyrin (MnTAPP) was synthesized and attached to graphene quantum dots (GQDs) via covalent and π-π interaction to give [email protected] and MnTAPP--GQDs, respectively. There was an increase (using dynamic light scattering and transmission electron microscopy) in size of the GQDs in the presence of the porphyrin due to aggregation. The porphyrins in the absence and presence of GQDs were then adsorbed onto a glassy carbon electrode using drop and dry method. The electrochemical behavior was tested by cyclic voltammetry and chronoamperometry towards hydrazine. Both methods of combining MnTAPP with GQDs improved the activity of the electrocatalysis compared to individual components. [email protected] showed better catalytic rate constant of 4.36 × 102 Ms−1 and lowest LoD of 0.0023 mM followed by MnTAPP--GQDs. Furthermore, the sensor showed good selectivity in the presence of interfering analytes. All probes showed good stability.

Spectroscopic investigation on the binding interactions between graphene quantum dots and carbonic anhydrase

As a new member of the nanomaterials family, ultrasmall graphene quantum dots (GQDs) have shown broad application prospects in the field of biomedicine, but the analysis of their biological effects at the molecular level is yet limited. Herein, carbonic anhydrase (CA) was selected as a model protein to assess the interactions between GQDs and biomacromolecules. A range of spectroscopic techniques were employed to systematically investigate the binding interactions between GQDs and CA and the catalytic function of CA in the presence of GQDs was evaluated. Experimental results showed that GQDs could quench the intrinsic fluorescence of CA and the concentration dependent quenching efficiency exhibited an obvious deviation from the linear plot, indicating a static binding mode. Further investigation suggested that van der Waal interactions and hydrogen bonding were the main driving forces. Additionally, circular dichroism measurement showed that the binding of GQDs induced slight conformational changes of CA. The catalytic capability assessment proved that these binding interactions resulted in the reduction of the biological functions of CA. This comprehensive study provided important insight into the interaction of GQDs with biomacromolecules, which would be crucial for the further applications of GQDs and other nanomaterials in the biomedical field.

Graphdiyne/graphene quantum dots for development of FRET ratiometric fluorescent assay toward sensitive detection of miRNA in human serum and bioimaging of living cancer cells

An effective ratiometric fluorescence resonance energy transfer (FRET) assay developed for the sensitive and specific measurement of microRNAs-21 (miRNA-21) using graphdiyne quantum dots (GDQDs) as the new fluorescent probe. GDQDs with uniform size, narrow defined tunable emission peak and good crystallization synthesized via a classical solvothermal approach. In the sensing strategy, GDQDs modified with DNA probe exhibited strong fluorescence (FL) signal at 405 nm, while in the presence of graphene quantum dots (GQDs) duo to Förster-resonance-energy transfer process between GDQDs and GQDs, the fluorescence of GDQDs was efficiently quenched, meanwhile, a new fluorescence signal at 505 nm for GQDs provided. In the presence of miRNA-21, with the hybridization between miRNA-21 and GDQDs modified with DNA probe, the distance of GDQDs (donor) and GQD (acceptor) is increased, and the intensity fluorescent signal of GDQD recovered, which confirmed by decreasing of the average life times for GDQDs-DNA probe from 1.99 to 0.61ns after addition of GQDs, while the average life time increased again to 1.26 ns in the presence of micRNA-21 target. The ratio of the FL intensity (F405/F505) behaved precise and sensitive analytical efficiency for miRNA-21 detection with a good linear range from 5 pM to 200 nM and a detection limit of 0.5 pM (S/N = 3). More importantly, this RNA sensor was feasible to detect target microRNA-21 in the human serum sample and MCF-7 cell lines with a detection limit of 4 cells/10 μL. Furthermore, due to low cytotoxicity of GDQDs multicolour imaging of MDA-MB231 living cancer cells also utilized.

Synthesis of NiO Nanoparticles and Sulfur, and Nitrogen co Doped-Graphene Quantum Dots/ NiO Nanocomposites for Antibacterial Application

The human life is faced with bacterial infections which are one of the major cause of prevalence and mortality. Antibiotics have long been the preferred therapy for bacterial infections due to their cost-effectiveness and efficacy. In the field of overcoming microbial issues, new and emerging nanostructure-based materials have gotten a lot of attention. In this Study, NiO and sulfur, and nitrogen co doped-graphene quantum dots-decorated NiO nanocomposites (S,N-GQDs/NiO) are prepared via a simple hydrothermal method. Structural and morphological properties of products are determined via XRD, SEM, UV-Vis, and FTIR analysis. The prepared products are applied for the investigation of antibacterial activity against Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, and methicillin resistant Staphylococcus aureus (MRSA). The results showed that prepared S,N-GQDs/NiO nanocomposites have high antibacterial activity against Staphylococcus aureus among a wide range of microorganisms. For S,N-GQDs/NiO nanocomposites nanoparticles, the disk diffusion test proved that the highest growth inhibition zone was related to Staphylococcus aureus (17 mm). The presence of graphene quantum dots in S,N-GQDs/NiO nanocomposites facilitates reactive oxygen species (ROS) mechanism which lead to bet antibacterial activity.

Decrease of catalytic efficiency of Photinus pyralis firefly luciferase in the presence of graphene quantum dots

Objective(s): Firefly luciferase is a monooxygenase enzyme that emits flash of light during the enzymatic reaction. Luciferase has been used in many bioanalytical fields from ATP detection methods to in vivo imaging. In recent decades, focus has been carried out on nanoparticles for their fluorescence properties. Semiconductor quantum dots have unique tunable properties that turn them promising tools in biological and biomedical researches, as nanosensors, photo-electrochemical and light-emitting devices. Carbon-based nanoparticles such as graphene quantum dots (GQDs) have useful benefits such as low toxicity, suitable luminescence and easy preparation. Materials and Methods: In this study, recombinant P. pyralis luciferase was expressed and purified based on N-terminal His-tag and then kinetic parameters of enzyme activity such as Km and Vmax values in presence and absence of GQDs were calculated. Results: The results showed that Km for ATP and luciferin substrates in the presence of GQDs were increased. Fluorescence spectroscopy showed significant changes in protein structure or in fluorescence spectra and decrease in the activity of the luciferase in presence of GQD. Both loss of activity and increase of substrates Km showed decrease of catalytic efficiency presumably through structural alteration. Conclusion: From these data it can be concluded that the protein structure under the influence of GQD may have changed that lead to alteration of enzyme activity.

Colorimetric sensing of imidacloprid in cucumber fruits using a graphene quantum dot/Au (III) chemosensor

The current research presents a very simple method for the colorimetric detection of imidacloprid using a graphene quantum dot/Au (III) chemosensor. The results demonstrated that there is an interaction between Au3+ ions and the imidazole group of the pesticide toward reduction of Au3+ to Au0 in the presence of graphene quantum dots. This phenomenon changes the color of gold nanoparticles from yellow to grey or red, and causes a shift in the peak of localized surface plasmon resonance (LSPR) as gold nanoparticles are formed or aggregated based on the concentration of imidacloprid. Imidacloprid was determined by the developed sensor in a linear area of 0.01–1 ppm with a detection limit of 0.007 ppm. Therefore, a simple, quick, and sustainable sensor has been developed for the determination of the investigated analyte. Moreover, the sensor was applied to determine imidacloprid in the real cucumber samples fairly successful.

Preparation and characterization of selenium-decorated graphene quantum dots with high afterglow for application in photodynamic therapy.

Graphene quantum dots (GQDs) was synthesized using a simple, rapid and affordable method and decorated with selenium at different molar ratios for the first time to obtain an efficient sample for use in photodynamic therapy. Surface modification of GQDs was carried out using polyethylene glycol (PEG) for conjugation with protoporphyrin IX (PpIX). Synthesized GQDs (Se: 0.3%) at 180°C had an emission spectrum that fairly coincided with the absorption profile of PpIX. A relative decrease of about 62.48% in the emission intensity of anthracene was recorded under illumination with UVC light in the presence of GQDs (Se: 0.3%) and the reduction for clung GQDs (Se: 0.3%) and PpIX during 90 min was about 70.68%. Singlet oxygen (1 O2 ) generation was examined using a chemical method that showed significant enhancement in decomposition rate constant in clung GQDs-PEG-PpIX compared with GQDs and PpIX alone. Afterglow over 600 s showed that GQDs (Se: 0.3%) could be effective for near skin and even deep tumours.

All-carbon flexible supercapacitors based on electrophoretic deposition of graphene quantum dots on carbon cloth

In this work, a flexible, free-standing supercapacitor electrode fabricated using a combination of Graphene Quantum Dots (GQD) and carbon cloth. The GQD was synthesized using a simple peroxide-assisted hydrothermal method and was electrodeposited on carbon cloth to ensure intimate contact. The presence of GQD on the surface of the carbon cloth greatly enhanced its capacitance, resulting in a flexible EDLC electrode with an areal capacitance of 70 mF cm−2 at a scan rate of 50 mV s−1 even with a negligible mass loading. We have also demonstrated a fully-flexible symmetric full-cell fabricated using the GQD/carbon cloth composite with a high-rate capability, showing a rectangular CV curve even at a high scan rate of 1 V s−1 and capacitance of 24 mF cm−2 at a scan rate of 50 mV s−1 when flexed and un-flexed.

Facile design and development of photoluminescent graphene quantum dots grafted dextran/glycol-polymeric hydrogel for thermoresponsive triggered delivery of buprenorphine on pain management in tissue implantation

A novel nano-formulations of biocompatible, biodegradable and thermo-responsive graphene quantum dots (GQDs) loaded dextran/poly(N-isopropylacrylamide) (Dex/PNIPAM) copolymeric matrix was synthesized and analyzed the materials characterization, sustained drug delivery system, tissue feasibility in the tissue implantation site. This research report was aimed to grafting and functionalizing thermo-responsive (Dex/PNIPAM) copolymeric composite with presence of graphene quantum dots to achieve thermal responsive drug delivery (TrDD) with no harm effect in the implantation site. The synthesized GQD by using ionic liquid were evaluated by spectroscopic (DLS, PL, XRD and Raman spectroscopy) and Transmission electron microscopic analysis (TEM). The ultra-small GQDs loaded Dex/PNIPAM and was appeared to be asymmetric and open uniform porous structure, which can be significantly favorable for cell uptake and greatly influenced to be an effective drug carrier into the cellular compartment with good fluid flow. The PNIPAM polymeric composite were exhibited sustained and enhanced drug release percentages with increasing temperature at above low critical solution temperature (LCST) is 39 °C comparable to the cumulative drug release profile of below LCST (32 °C), which demonstrated that thermo-responsive polymer was played a significant role in the delivery system. The treated group of GQDs-Dex/PNIPAM was observed that no inflammation and shows noteworthy stromal cell infiltration, demonstrating that the synthesized drug carriers did not harm to the nerves and tissues and only was responsible for the pain management.

Bismuth vanadate/graphene quantum dot: A new nanocomposite for photoelectrochemical determination of dopamine

A photoelectrochemical sensor for dopamine was fabricated by the immobilization of bismuth vanadate (BiVO4) and graphene quantum dots on a fluorine-doped tin oxide (FTO) glass electrode. Electrochemical impedance spectroscopy experiments demonstrated that the presence of graphene quantum dots contributed to the decrease in charge transfer resistance of the sensor under irradiation of visible light in the presence of dopamine. The photocurrent signals obtained were proportional to the dopamine concentration from 3.6 × 10−8 to 2.5 × 10−4 mol L−1, with a detection limit estimated at 8.2 × 10−9 mol L−1 and a limit of quantification at 2.7 × 10−8 mol L−1.

Strong Enhancement of the Chemiluminescence of Hydrogen Sulfite-Oxidant Systems in the Presence of N,S-Doped Graphene Quantum Dots, and Its Application to the Determination of Folic Acid in Spinach and Kiwifruit Samples

The oxidation of bisulfite by classical oxidants such as hypochlorite, hydrogen peroxide, and permanganate is accompanied by weak chemiluminescence (CL). It is reported here that the CL is strongly enhanced in the presence of nitrogen/sulfur co-doped graphene quantum dots (N,S-GQD), nitrogen-doped graphene quantum dots (N-GQD), or graphene quantum dots (GQD). The weak CL of the NaHSO3-NaClO system and the NaHSO3-H2O2 system in the neutral medium and of the NaHSO3-KMnO4 system in acidic solution is more than 1000-fold enhanced in the presence of N,S-GQD, about sixfold in the presence of N-GQD, and twofold in the presence of GQD. Fluorescence spectra and CL spectra indicate that the N,S-GQD-sensitized enhancement originates from energy transfer and electron transfer annihilation effects on the CL system. It is also reported that folic acid (FA; vitamin B9) causes a notable diminution in the N,S-GQD-NaHSO3-NaClO system. Based on this finding, a sensitive CL method is developed for the determination of FA in food samples. The method works in the 0.5 to 70.0 μmol/L FA concentration range and the limit of detection is 78.0 nmol/L.

Multifunctional GQDs-Coated Fe/Bi Nanohybrids for CT/MR Dual Imaging and in vitro Photothermal Therapy

Introduction: The multipurpose nanocomposites have gained growing biomedical attention as promising nanotheranostics to improve The effectiveness of cancer treatment, which concurrently combine advantages of the therapeutic and diagnostic techniques into one nanosystem. The “all-in on” probes not only help to ablate cancerous tumors, but also allow to optimize and monitoring of treatment. Materials and Methods: iron/bismuth nanohybrid was synthesized in presence of graphene quantum dots for the co-integration of diagnostic and therapeutic functions into a single nanoprobe (referred to as GQDs-Fe/Bi NPs). Then, for further applications, blood compatibility and cytotoxicity, as important tissues, of different concentration of GQDs-Fe/Bi NPs were investigated by hemolysis test and MTT test, respectively. A 1.5 T MRI scanner (Siemens Avanto- Germany) was employed to measure MR contrast ability of GQDs-Fe/Bi NPs with various concentrations of Fe. In additional, the phantom CT images were taken at the various concentrations of the Bi and iodine using a clinical CT scanner (GE HiSpeed) at operating voltages of 80,120 and 140 kVp. The acquired images were analyzed with imageJ software. To study the photothermal performance, the GQDs-Fe/Bi NPs suspension with a series of concentrations of active Bi metal were exposed to a NIR laser (808 nm, 1.7 W ・cm−2) for 10 min. Results: Such theranostic agent not only shows strong near-infrared (NIR) absorbance, but also offers high contrast for X-ray computed tomography (CT) and magnetic resonance (MR) imaging to the imaging-guided NIR laser irradiation deliver and selectively heating of tumor. Fe3O4 component involved in the hybrid showed the good magnetization property (48.59 emu/g) with excellent performance on magnetic resonance imaging and high relaxivity time (62.34 mM−1 s−1). Synergistically, the presence of the Bi component with high atomic number (Z=83) in the GQDs-Fe/Bi nanohybrid offered high- X-ray contrast for CT imaging. Furthermore, thanks to the high photothermal conversion efficiency of 31.88%, co-delivery of GQDs-Fe/Bi NPs and NIR-radiation can effectively kill the cancer cells. Conclusion: the high theranostic performance of GQDs-Fe/Bi NPs can simultaneously use for CT/MR imaging-guided cancer photothermal therapy purposes.