Graphene Quantum Dots Research Articles

Chitosan-graphene quantum dot-based molecular imprinted polymer for oxaliplatin release

Molecularly imprinted polymers (MIPs) have garnered the interest of researchers in the drug delivery due to their advantages, such as exceptional durability, stability, and selectivity. In this study, a biocompatible MIP drug adsorption and delivery system with high loading capacity and controlled release, was prepared based on chitosan (CS) and graphene quantum dots (GQDs) as the matrix, and the anticancer drug oxaliplatin (OXAL) as the template. Additionally, samples without the drug (non-imprinted polymers, NIPs) were created for comparison. GQDs were produced using the hydrothermal method, and samples underwent characterization through FTIR, XRD, FESEM, and TGA. Various experiments were conducted to determine the optimal pH for drug adsorption, along with kinetic and isotherm studies, selectivity assessments, in vitro drug release and kinetic evaluations. The highest drug binding capacity was observed at pH 6.5. The results indicated the Lagergren-first-order kinetic model (with rate constant of 0.038 min−1) and the Langmuir isotherm (with maximum adsorption capacity of 17.15 mg g−1) exhibited better alignment with the experimental data. The developed MIPs displayed significant selectivity towards OXAL, by an imprinting factor of 2.88, in comparison to two similar drugs (cisplatin and carboplatin). Furthermore, the analysis of the drug release profile showed a burst release for CS-Drug (87% within 3 h) at pH 7.4, where the release from the CS-GQD-Drug did not occur at pH 7.4 and 10; instead, the release was observed at pH 1.2 in a controlled manner (100% within 28 h). Consequently, this specific OXAL adsorption and delivery system holds promise for cancer treatment.

Graphene quantum dots mediated acrylamide biosensing

Acrylamide (AA) is an unwanted food processing contaminant produced during cooking at high temperatures through the Maillard reaction between asparagine and reducing sugars or reactive carbonyls. In humans, it causes significant neurotoxicity, genotoxicity, and possible carcinogenicity. AA is categorized as a ‘Group 2A’ carcinogen by the International Agency for Research on Cancer (IARC). Bread, biscuits, and potato crisps are examples of foods heavy in starch that contain significant quantities of AA. Consequently, the detrimental effects of AA on human health make determining its quantitative content a crucial matter. Here, by immobilizing Hemoglobin nanoparticles (HbNPs) onto graphene quantum dots (GQDs) decorated pencil graphite (PG) electrode, we have developed a highly sensitive electrochemical biosensor for the detection of AA. Using cyclic voltammetry (CV), scanning electron microscopy (SEM), and electrochemical impedance spectroscopy (EIS), the developed working electrode (HbNPs/GQDs/PG) was examined at different stages of its preparation. The ideal pH and temperature for the fabricated biosensor were 5.0 and 35 °C, respectively and the biosensor demonstrated an acceptable level of selectivity, sensitivity, and stability along with a broad linear range (10 nM to 120 nM) and a low detection limit of 2.70 nM. The suggested strategy made use of less costly raw materials to ensure that it should be both effective and environmentally friendly. The sensor was effectively used to measure the amounts of AA in potato crisp samples.

Impact of Tamm plasmon structures on fluorescence and optical nonlinearity of graphene quantum dots

Graphene Quantum Dots (GQDs) are crucial in biomedicine for sensitive biosensing and high-resolution bioimaging and in photonics for their nonlinear optical properties. Integrating GQDs with photonic structures enhances optical properties by optimizing light-matter interactions and enabling precise control over their emission wavelengths. In this work, we explore a facile synthesis method for GQDs by pulsed laser irradiation in chlorobenzene and highlight the transformative potential of Tamm Plasmon Cavity (TPC) structures for tuning and amplifying the photoluminescence and nonlinear optical properties of GQDs. The characterization of GQDs revealed their exceptional properties, including efficient optical limiting and stable photoluminescence. The study demonstrated that the TPC structure significantly amplifies nonlinear optical effects due to the high light-matter interaction, indicating the potential for advanced optical systems, including optical limiters and nonlinear optical devices. Furthermore, introducing GQDs into the TPC structure leads to a significant enhancement and tuning of fluorescence emission. The Purcell effect, in combination with the confined electromagnetic fields within the TPC, increases the spontaneous emission rate of GQDs and subsequently enhances the fluorescence intensity. This enhanced and tunable fluorescence has exciting implications for high-sensitivity applications such as biosensing and single-molecule detection.

Investigation on the synergistic effect and thermal properties of poly-hydroxyethyl methacrylate encapsulated graphene quantum dot-paraffin hybrid nanofluid

In this study, a novel water-based hybrid nanofluid was developed using poly-hydroxyethyl methacrylate-encased graphene quantum dot-paraffin nanocomposite (HEMA GQD-P). Graphene quantum dots (GQD) with an average size of 10 to 15 nm were synthesized by citric acid nucleation and the HEMA GQD-P nanocomposites were synthesized by an emulsion polymerization reaction. The emission spectra of GQD obtained using photo-luminescent spectroscopy confirm the occurrence of quantum confinement effect. The synthesis of HEMA GQD-P was carefully carried out to ensure its optimal properties. The synergistic effect due to high thermal conductivity of GQD and high latent heat capacity of paraffin were recognized in the enhanced properties of nanocomposite and hybrid nanofluid. The latent heat capacity of the synthesized nanocomposite was found to be 21.8 % higher than the pure paraffin. The prepared hybrid nanofluid possesses high dispersion stability at pH 7 and the thermal conductivity of the hybrid nanofluid enhances with an increase in nanoparticle concentration. A maximum thermal conductivity enhancement of 53 % (±2) was obtained for the hybrid nanofluid (0.3 vol%) at 30 °C. The present work reveals that the encapsulation of GQD-paraffin in a poly-hydroxyethyl methacrylate shell creates nanocomposites with high heat transfer properties. The synergistic effect of the HEMA GQD-P enhances their potential in the preparation of hybrid nanofluids with enhanced properties for desired thermal management applications.

Design of Polymeric Nanoparticles for Theranostic Delivery of Capsaicin as Anti-Cancer Drug and Fluorescent Nitrogen-Doped Graphene Quantum Dots.

In recent years, multifunctional nanocarriers that provide simultaneous drug delivery and imaging have attracted enormous attention, especially in cancer treatment. In this research, we designed a biocompatible fluorescent multifunctional nanocarrier for the co-delivery of capsaicin (CPS) and nitrogen-doped graphene quantum dots (N-GQDs) using the pH sensitive amphiphilic block copolymer (poly(2-ethyl-2-oxazoline)-b-poly(ε-caprolactone), PEtOx-b-PCL). The effects of the critical formulation parameters (the amount of copolymer, the concentration of poly(vinyl alcohol) (PVA) as a stabilizing agent in the inner aqueous phase, and volume of the inner phase) were evaluated to achieve optimal nanoparticle properties using Central Composite Design (CCD). The optimized nanoparticles demonstrated a desirable size distribution (167.8±1.4nm) with a negative surface charge (-19.9±0.4) and a suitable loading capacity for capsaicin (70.80±0.05%). The CPS & N-GQD NPs were found to have remarkable toxicity on human breast adenocarcinoma cell line (MCF-7). The solid fluorescent signal was acquired from cells containing multifunctional nanoparticles, according to the confocal microscope imaging results, confirming the significant cellular uptake. This research illustrates the enormous potential for cellular imaging and enhanced cancer therapy offered by multifunctional nanocarriers that combine drug substances with the novel fluorescent agents. This article is protected by copyright. All rights reserved.

New bioelectrode based on graphene quantum dots-polypyrrole film and Concanavalin A for pathogenic microorganism detection

Infections caused by microorganisms are a public health problem worldwide. New biodetection systems are essential to diagnose with accuracy resulting in more effective treatment. In this work, we propose a ConA-conjugated graphene quantum dots and polypyrrole film-based biosensor for label-free detection of Candida albicans, Candida glabrata, Candida tropicalis, E. coli, B. subitilis, and S. aureus. We modified polypyrrole and graphene quantum dots (PPY-QDGs) with Concanavalin A (Con A) lectin. ConA is a glucose/mannose-specific lectin. The results showed that ConA lectin has the highest binding affinity for C. tropicalis and S. subtilis. PPY-GQDs-ConA binding profile revealed differential response for Candida spp (C. tropicalis >C. albicans >C. glabrata) and bacterial (B. subtilis >S. aureus >E. coli). The limits of detection (LOD) obtained were 1.42 CFU/mL for C. albicans, and 3.72 CFU/mL for C. glabrata. C. tropicalis yielded a LOD of 0.18 CFU/mL. The respective LODs for the evaluated bacteria were 0.39 CFU/mL for S. aureus, 0.72 CFU/mL for S. subtilis, and 2.63 CFU/mL for E. coli. The differential response obtained for the sensor can be attributed to the heterogeneous distribution of carbohydrates on the microorganism's surfaces. The proposed system based on a flexible substrate is effective for microbiological diagnosis.

Defective graphene-nanomaterials derived from banana-biomass for simultaneous electrochemical detection of xanthine, hypoxanthine, and uric acid: Insights from scanning electrochemical microscopy on edge and basal planes

While graphene and other graphene-based materials are promising for electrochemical sensors, developing a simple synthesis method and understanding how their structure affects their performance remains challenging. This study introduces a straightforward method to produce highly defective graphene-based nanomaterials (BP-GNMs) from banana pulp (BP) biomass. These BP-GNMs are suitable for efficiently detecting purine bases (xanthine (X), hypoxanthine (Hx), and uric acid (UA)) simultaneously using electrochemical techniques. The synthesis process involves heating at 180 °C in air. Compared to BP-derived graphene quantum dots (BP-GQDs) made using a hydrothermal method, BP-GNMs exhibit significantly better electrochemical activity. This is shown by well-defined, separated peaks with high currents in electrochemical measurements of the purine bases. In this study, we compared the physicochemical properties of BP-GNMs and BP-GQDs using various techniques like FESEM, TEM, XPS, UV–Vis, Raman, and FTIR spectroscopy. Our analysis revealed the formation of layered nanomaterials based on graphene, with sizes ranging from 400 mm to 10 μm. These nanomaterials exhibited a balanced ratio of sp2-bonded carbon (sp2C) to sp3-bonded carbon (sp3C). This balanced ratio is attributed to the presence of both defective basal planes (containing sp2C) and edge planes (containing sp3C) on the BP-GNMs. The heterogeneity on the surface in terms of edge and basal planes of the materials was viewed using scanning electrochemical microscopy (SECM) technique with ferrocene-carboxylic acid as a redox probe. As a practical application of this low-cost biomass material, an efficient and separation-free simultaneous electrochemical sensing of X, Hx and UA in various fishes and human urine samples were demonstrated with a recovery of 100±2%.

Striking antithermal quenching and waterproofness of Mn4+-doped fluoride phosphors induced by synergy of double coating and single passivation

Manganese (IV) (Mn4+)-doped fluoride phosphors generally suffer two pressing problems, thermal quenching (TQ) and poor water resistance. This study reports striking luminous intensity enhancement, anti-TQ property, and waterproofness of Mn4+-doped potassium fluosilicate phosphors induced by synergy of double coating and single passivation (coating with hydroxylated graphene quantum dots (GQDs), passivation with H2O2, and coating with K2SiF6). The luminous intensity of the phosphor is approximately 163 % of that of K2SiF6:Mn4+. The integrated emission intensity at 150 °C is 129.3 % higher than that at 30 °C. The emission intensity remains 93.2 % of the initial value after immersion in water for 480 min. These results are attributed to energy transfer from GQDs to Mn4+ and the formation of a stable Mn-free shell layer. In particular, the white light-emitting diodes produced using the phosphors maintained 99.6 % luminescence efficiency after 240 h of operation in high-temperature, high-humidity environments. We believe that this study provides a feasible approach to simultaneously enhance the thermal stability and waterproofness of Mn4+-doped fluoride phosphors.

Nitrogen-Doped Graphene Quantum Dots Incorporated into MOF-Derived NiCo Layered Double Hydroxides for Nonenzymatic Lactate Detection in Noninvasive Biosensors

Nitrogen-Doped Graphene Quantum Dots Incorporated into MOF-Derived NiCo Layered Double Hydroxides for Nonenzymatic Lactate Detection in Noninvasive Biosensors

Electric Dipole Coupling of a Bilayer Graphene Quantum Dot to a High-Impedance Microwave Resonator.

We implement circuit quantum electrodynamics (cQED) with quantum dots in bilayer graphene, a maturing material platform that can host long-lived spin and valley states. Our device combines a high-impedance (Zr ≈ 1 kΩ) superconducting microwave resonator with a double quantum dot electrostatically defined in a graphene-based van der Waals heterostructure. Electric dipole coupling between the subsystems allows the resonator to sense the electric susceptibility of the double quantum dot from which we reconstruct its charge stability diagram. We achieve sensitive and fast detection of the interdot transition with a signal-to-noise ratio of 3.5 within 1 μs integration time. The charge-photon interaction is quantified in the dispersive and resonant regimes by comparing the resonator response to input-output theory, yielding a coupling strength of g/2π = 49.7 MHz. Our results introduce cQED as a probe for quantum dots in van der Waals materials and indicate a path toward coherent charge-photon coupling with bilayer graphene quantum dots.

Valley-dependent transport through graphene quantum dots due to proximity-induced, staggered spin-orbit couplings

Valley-dependent transport through graphene quantum dots due to proximity-induced, staggered spin-orbit couplings

One-Step Synthesis of N-Doped Graphene Quantum Dots via Plasma Contacting Liquid for Multiple Heavy Metal Ion Detection

One-Step Synthesis of N-Doped Graphene Quantum Dots via Plasma Contacting Liquid for Multiple Heavy Metal Ion Detection

The pyrolytic oil and castor oil methyl ester blend with nano‐additive as fuel in a diesel engine for environmental safety and preservation

AbstractThe increase in the use of plastic products and disposal of the same pose a threat to the world community due to its poor biodegradability. Chemically treating the waste plastic to extract oil and using as the fuel in the form of blends will safeguard the environment. It was observed that viscosity and lubricity of such oils were lower than standard diesel. High Ricinoleic fatty acid ester is added to improve the lubricity of novel pyrolytic blend. Lower blends were prepared for the investigation. Cator ester was added to Pyro‐Diesel along with graphene quantum dot (GQD). The fuel blend is prepared with concentration of 30 ppm GQD nano‐particles. The investigation was made on using CME and PD20 blend. The blend was prepared using Castor oil methyl ester, Pyrolytic oil and nano particle Graphene Quantum Dot (GQD). GQD has extraordinary ecological characteristics such as biocompatibility, large surface area excellent solubility. This combination is a novel work which resulted in reduced emissions. The results reveal that oxides of nitrogen and smoke were increased for all the ternary blends but combustion characteristics improved. The performance of PCD10 (10% CME + 20% Pyro + 70% Diesel) was higher than that of Pyro‐Diesel blend. Hence, ternary blend may be chosen as fuel.

Construction of advanced Nb9VO25 electrode material by introducing graphene quantum dot for high energy supercapacitors with exceptionally high diffusive capacitance

Unreasonable tunnel structure and low intrinsic conductivity limit practical applications of niobium oxide in high-performance supercapacitors. The study reports the construction of Nb9VO25 electrode material via coordination of Nb(V) and V(V) with histidine and serine-functionalized and boron-doped graphene quantum dot (HSBGQD) and subsequent annealing. The introduction of HSBGQD and rambutan peel leads to formation of small Nb9VO25 nanocrystal and low valent Nb and V species. The combination of small size and more reasonable tunnel structure accelerates the ion diffusion. The Nb(IV) and V(IV) double doping optimizes the tunnel structure, narrows the bandgap and creates new pathways for high-speed electron transfer. The integration of defect engineering with graphene surface modification enhance the intrinsic conductivity. The Nb9VO25 electrode shows exceptionally high specific capacitance of 2925.3 F/g, which is more than 142 times that of Nb2O5. The symmetrical supercapacitor with Nb9VO25 electrodes and PVA/Li2SO4 gel electrolyte offers high specific capacitance (263 F/g at 1 A/g), high-rage capacity (138 F/g at 50 A/g), cycling stability (capacitance retention of 99.4 % after 10000-cycle), energy density (146 W h Kg−1 at 996 W Kg−1 and 77 W h Kg−1 at 50181 W kg−1) and broad application prospect in wearable electronic devices.

Theoretical insights into the activity of the N doped graphene quantum dots for oxygen reduction reaction as a function of the shape and edge terminations

We have investigated the possible activity of the N-doped graphene quantum dots (N-GQD) toward the oxygen reduction reaction (ORR) using density functional theory (DFT) method. The effect of the shape (triangular (N-GQDT), rhombohedral (N-GQDR) and hexagonal (N-GQDH)), connected both with the zigzag (zz) and armchair (ac) edge terminations of the GQD and with the location of the N atom across the sheets are investigated. The activity of part of the studied N-GQDTac, GQDRac, N-GQDHac and N-GQDHzz structures improves significantly compared to the similar pristine structures. On the other hand, no matter on the location of the N in the N-GQDTzz and in the N-GQDRzz, their activity gets worsen, when compared with the activity of the pristine structures or with the activity of the other four investigated structures. N-GQDTac and N-GQDRac are the structures with the most possible locations of N, that generates active sites. CN bond breaking takes place in the triangular shapes (N-GQDTzz and N-GQDTac) when oxygen adsorption takes place. These bonds are less likely to regenerate and new reaction sites are created. The new reaction site created on the N-GQDTzz represents a possible active site compared to the site generated on the N-GQDTac, that is highly inactive.

2D-network of boron-functionalized N-doped graphene quantum dots for electrochemical sensing of dopamine

A glassy carbon electrode (GCE) modified by boron-functionalized N-doped graphene quantum dots (B-GQDs) was employed for the electrochemical determination of dopamine (DA), a neurotransmitter. The B-GQDs were obtained by hydrothermal etching of GO with H2O2 and NH3 in the presence of H3BO3. By using various techniques, including transmission electron microscopy, atomic force microscopy, molecular absorption spectrometry, fluorescence, ICP-MS, and zeta potential analysis, it was demonstrated that B-GQDs are self-organized in 2D-network, being N-doped GQDs nanoparticles crosslinked by H3BO3. The GCE modification was carried out using the drop-casting method with B-GQDs in Nafion®, previously dispersed through ultrasonication. For the first time, the synthesized nanomaterial was tested in the electroanalysis of neurotransmitters. The B-GQDs/Nafion®/GCE modification led to a significant increase in peak currents in the presence of DA. The electrochemical and interfacial characteristics of the sensors were evaluated by cyclic voltammetry (CV). Under optimized square wave voltammetry and supporting electrolyte conditions, a linear dependence between the anodic peak current and DA concentration was observed in the range of 0.7 to 188 μmol L−1 (R2 = 0.9991). The limit of detection (LOD) was estimated at 0.05 μmol L−1. Selectivity was confirmed in the presence of potential interferents found in urine, with interference response below 12 %. The sensor exhibited excellent intra-day and inter-day repeatability, with a relative standard deviation of 4.12 % and 4.66 %, respectively. Electrochemical determination of DA was conducted in artificial urine samples (Surine®), with recovery values of 90–101 %. The new analytical platform B-GQDs/Nafion®/GCE demonstrated promising characteristics for application in biological and/or pharmaceutical analysis.

Preparation of waterborne anti-counterfeiting ink based on dual luminescent nanohybrids of bacterial cellulose nanocrystals and lanthanide‑nitrogen co-modified GQDs

To address the growing challenge of counterfeit prevention, this study developed a novel anti-counterfeiting ink system based on bacterial cellulose nanocrystals (BCNC) and lanthanide (Er, Yb)‑nitrogen (N) co-dropped graphene quantum dots (GQDs), which exhibited both photoluminescence (PL) and upconversion photoluminescence (UCPL) fluorescent properties as well as excellent rheological characteristics. The Er/Yb/N-GQDs with positive charges were synthesized by a one-step hydrothermal method and subsequently assembled with negatively charged BCNC through electrostatic self-assembly to fabricate a novel nanohybrid, Er/Yb/N-GQDs-BCNC. Raman spectroscopy results indicated an enhancement in the graphitization of GQDs due to lanthanide modification. The TEM results demonstrated a homogeneous distribution of Er/Yb/N-GQDs on BCNC, while XRD, FTIR, and XPS analyses confirmed their physical binding, thus validating the successful synthesis of novel nanohybrids. Then, Er/Yb/N-GQDs-BCNC was introduced into PVA waterborne ink and exhibited dual anti-counterfeiting properties by emitting blue fluorescence at Em 440 nm under Ex 370 nm and green fluorescence at Em 550 nm under Ex 980 nm. Furthermore, the incorporation of BCNC significantly enhanced the thixotropic behavior and yield stress of the PVA waterborne ink. This enhancement made the dual anti-counterfeiting fluorescent ink more suitable for diversified applications on different devices and various substrates, thus providing a novel approach for convenient and rapid information encryption and high security anti-counterfeiting.

Fabrication of a Label-Free Immunosensor Using Surface-Engineered AuPt@GQD Core-Shell Nanocomposite for the Selective Detection of Trace Levels of Escherichia coli from Contaminated Food Samples.

Fabrication of label-free immunosensors is highly necessitated due to their simplicity, cost-effectiveness, and robustness. Herein, we report the facile development of a label-free, direct, rapid, capacitive immunosensor for ultrasensitive and rapid recognition of trace levels of Escherichia coli from contaminated food samples. This was achieved using gold platinum core-shell nanoparticles loaded with graphene quantum dots (AuPt@GQDs) that were utilized as electrode modifiers. The incorporation of GQDs to the surface of AuPt core-shell nanoparticles was performed using the "greener" probe-sonication method. The electrochemical properties of AuPt@GQDs, determined using cyclic voltammetry and electrochemical impedance spectroscopy, suggested the optimized loading concentration of AuPt to be 0.05% in the core-shell nanocomposite to exhibit the highest current response. Furthermore, immobilization of anti-E. coli monoclonal antibodies (anti-E. coli mAb) onto the surface of modified electrodes was performed using amine coupling. The high specific binding of E. coli cells onto the surface of the immuno-electrode was measured as a direct function of change in transient capacitance with time that was measured at low and high frequencies. The resultant immunosensor (bovine serum albumin/anti-E. coli mAb/AuPt0.05@GQDs/FTO) demonstrated a detection range (5 to 4.5 × 103 cells/mL), with the detection limit as low as 1.5 × 102 cells/mL, and an excellent sensitivity ∼171,281.40 μF-1 mL cells-1 cm-2 without the use of any labels (R2-0.99). These findings were further verified using real sample analysis wherein the immuno-electrode demonstrated outstanding sensitivity, the highest noticed so far. More interestingly, the high resuability ∼48 weeks (RSD-5.92%) and excellent reproducibility in detection results (RSD ∼ 9.5%) testify its potential use in a clinical setting. The results reveal the usefulness of the surface-engineered AuPt@GQDs core-shell nanocomposite as an electrode modifier that can be used for the development of newer on-site monitoring devices to estimate trace levels of pathogens present as contaminants in food samples.

Developing innovative point-of-care electrochemical sensors empowered by cardiac troponin I-responsive nanocomposite materials

This study integrates dopamine (DA) electropolymerization, epitope imprinting, and nanomaterials (i.e., gold nanoparticles (AuNP) and graphene quantum dots (GQD)) to develop three distinct electrochemical sensors (DA-AuNP-MIP, DA-GQD-MIP, and DA-AuNP-GQD-MIP) for detecting cardiac troponin I (cTnI) with assessing their sensitivity, selectivity, and specificity profiles. The sensors exhibited high affinity for the target biomarker, enabling detection within a concentration range of 0.01–20 ng mL−1, with dissociation constants ranging from 2.7 to 69 pM. The successful fabrication of sensors was also confirmed through atomic force microscopy (AFM), scanning electron microscopy (SEM), fluorescence microscopy, contact angle measurements, cyclic voltammetry (CV), square wave voltammetry (SWV), and electrochemical impedance spectroscopy (EIS). The cTnI selectivity assessment of imprinted nanosensors compared to their non-imprinted counterparts at 0.01–2.5 ng mL−1 showed that the DA-AuNP-GQD-MIP sensor yielded a maximum imprinting factor of 5.9. A negligible cross-reactivity for DA-AuNP-MIP and DA-AuNP-GQD-MIP sensors was found against glucose, adenovirus epitope, another cTnI epitope, bovine serum albumin (BSA), transferrin, and neuron-specific enolase (NSE). Epitope specificity at various concentrations (10–60 nM), concentration-dependent cTnI detection in human serum (0.01–10 ng mL−1) and sensor recovery rates (0.1–10 ng mL−1) in human serum were determined with the best-performing sensor (i.e., DA-AuNP-GQD-MIP). The sensor demonstrated very high epitope specificity in comparison to another cTnI epitope as well as excellent detection performances in human serum studies. The newly engineered epitope-mediated electrochemical sensing platform showcases considerable potential for precise and straightforward diagnosis of coronary artery diseases, aiming to materialize a cost-effective Point-of-Care Testing (POCT) system.

The impact of the nitrogen atom on the optoelectronic, nonlinear optical, and thermodynamic properties of graphene quantum dots derived from dibenzocoronene: A DFT investigation

Because of their potential applications in electricity and photonics, graphene quantum dots (GQDs) with intriguing physical characteristics have attracted a lot of attention. Here we use density functional theory (DFT) with the B3LYP functional associated with the 6–31++G(d,p) basis to explore the effect of the nitrogen atom on the optoelectronic, nonlinear optical, and thermodynamic properties of dibenzocoronene (DBC) isomers. The pristine molecules of the DBC isomers have HOMO-LUMO energy gaps of 3.39 eV (DBCa), 3.39 eV (DBCb) and 3.65 eV (DBCc). Inserting a nitrogen atom into the DBC molecular structure considerably reduces the energy gap between these two orbitals. The materials thus obtained after nitrogen doping are DBCa-N, DBCb-N, and DBCc-N and have respective gap energies of 2.05, 1.80, and 1.65 eV (in other words, less than 3 eV). It can therefore be deduced that the compounds studied will be used as semiconductors in electronics. The static polarizabilities α of the N-doped DBC isomers obtained are 442.960, 443.523, and 455.657 au, respectively, each of these values being 4 times higher than that of the organic reference molecule for non-linear optical properties (para-nitroaniline pNA α = 114.7 au), while the first-order hyperpolarizabilities β obtained are 2689.838, 5572.137, and 12717.472 au, respectively. These values are approximately 2.5, 5, and 12 times higher than those of para-nitroaniline (β = 1072.44 au). Our results confirm that the investigated DBC nitrogen derivatives are good non-linear optical materials for photonics, data storage, dynamic imaging, optical signal processing, and computer systems. All the calculated thermodynamic properties show that the proposed molecules can be easily produced. This manuscript thus stands out as a good compass in the rational design of organic semiconductors for efficient electronic devices.