Computational studies and biosensory applications of graphene-based nanomaterials: a state-of-the-art review

Recent advances in biosensors detecting biomarkers from exhaled breath and saliva for respiratory disease diagnosis

The global demand for rapid and non-invasive diagnostic methods for respiratory diseases has significantly intensified due to the wide spread of respiratory infectious diseases. Recent advancements in respiratory disease diagnosis through the analysis of exhaled breath and saliva has attracted great attention all over the world. Among various analytical methods, biosensors can offer non-invasive, efficient, and cost-effective diagnostic capabilities, emerging as promising tools in this area. This review intends to provide a comprehensive overview of various biosensors for the detection of respiratory disease related biomarkers in exhaled breath and saliva. Firstly, the characteristics of exhaled breath and saliva, including their generation, composition, and relevant biomarkers are introduced. Subsequently, the design and application of various biosensors for detecting these biomarkers are presented, along with the innovative materials employed as sensitive components. Different types of biosensors are reviewed, including electrochemical, optical, piezoelectric, semiconductor, and other novel biosensors. At last, the challenges, limitations, and future trends of these biosensors are discussed. It is anticipated that biosensors will play a significant role in respiratory disease diagnosis in the future.

Investigating the electronic properties of edge glycine/biopolymer/graphene quantum dots

This study systematically investigated four types of graphene quantum dots (GQDs) AHEX, ZTRI, ZHEX, and ATRI, and their interactions with glycine to form GQD-glycine complexes. Utilizing density functional theory (DFT) and the PM6 semiempirical method, the study analyzed electronic properties and structure-activity relationships. Global reactivity indices were calculated using Koopmans' theorem, and quantitative structure-activity relationship (QSAR) parameters were assessed via SCIGRESS 0.3. The study further explored interactions using density of states (DOS) and quantum theory of atoms in molecules (QTAIM) analyses. Key findings revealed that glycine interaction significantly increased the total dipole moment (TDM) and decreased the HOMO/LUMO energy gap (ΔE) for the GQD-glycine complexes. Notably, ZTRI/glycine showed a TDM of 4.535 Debye and a reduced ΔE of 0.323 eV, indicating enhanced reactivity. Further interactions with cellulose, chitosan, and sodium alginate identified the ZTRI/glycine/sodium alginate composite as the most reactive, with a TDM of 8.020 Debye and the lowest ΔE of 0.200 eV. This composite also exhibited the highest electrophilicity index (56.421) and lowest chemical hardness (0.145 eV), underscoring its superior reactivity and stability. DOS analysis revealed that biomolecules contributed the most to molecular orbitals, with carbon atoms contributing the least. QTAIM analysis confirmed the greater stability of the ZTRI/glycine/sodium alginate complex compared to other studied composites. These results highlight the enhanced reactivity and stability of GQDs when interacting with glycine and sodium alginate.

Improved photocatalytic performance of cobalt doped ZnS decorated with graphene nanostructures under ultraviolet and visible light for efficient hydrogen production

Highly dispersed Cobalt doped ZnS nanostructures were successfully fabricated on the surfaces of graphene sheets via a simple hydrothermal method. X-ray diffraction (XRD), X-ray photocurrent spectroscopy (XPS), Raman spectroscopy (RS), Fourier transform infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM) were utilized to analyze the structural characteristics of the cobalt doped ZnS decorated with grapheneCo x Zn 1 - x S rGO nanostructures (NSs). UV-visible optical absorption (UV-vis) studies were conducted to investigate their optical properties. In laboratory studies utilizing water and visible light, the photocatalytic activity ofCo x Zn 1 - x S rGO NSs at (x = 0, 1, 2, 4 and 6 atm.%) were evaluated. Graphite Oxide (GO) was successfully transformed into sheets of graphene andCo x Zn 1 - x S rGO NSs possessed a crystalline structure according to the findings of XRD, RS and FTIR analysis. SEM investigation showed graphene sheets enhanced with ZnS NSs possessed cuboidal, spheroidal form of structure and displayed a paper like appearance. UV-vis confirmed a noticeable rapid increase in transmittance along the UV wavelength area and confirmed a highly transparent NSs in the wavelength range of (180-800 nm). Calculations using density functional theory (DFT) revealed that the Co NSs have more negative conduction bands than ZnS, allowing for effective electron transfer from cobalt to ZnS and exhibiting a band gap decrease as Co content increased. TheCo 0.04 Zn 0.96 S rGO NSs sample had the highest photocatalytic activity, measured at 7648.9 μ mol h - 1 . A combination of improved dispersion properties, greater surface area, increased absorption and enhanced transfer of photogenerated electrons,Co x Zn 1 - x S rGO NSs increased the photocatalytic hydrogen generation activity.

Nanotoxicity of two-dimensional nanomaterials on human skin and the structural evolution of keratin protein

Two-dimensional (2D) materials have been increasingly widely used in biomedical and cosmetical products nowadays, yet their safe usage in human body and environment necessitates a comprehensive understanding of their nanotoxicity. In this work, the effect of pristine graphene and graphene oxide (GO) on the adsorption and conformational changes of skin keratin using molecular dynamics simulations. It is found that skin keratin can be absorbed through various noncovalent driving forces, such as van der Waals (vdW) and electrostatics. In the case of GO, the oxygen-containing groups prevent tighter contact between skin keratin and the graphene basal plane through steric effects and electrostatic repulsion. On the other hand, electrostatic attraction and hydrogen bonding enhance their binding affinity to positively charged residues such as lysine and arginine. The secondary structure of skin keratin is better preserved in GO system, suggesting that GO has good biocompatibility. The charged groups on GO surface perform as the hydrogen bond acceptors, which is like to the natural receptors of keratin in this physiological environment. This work contributes to a better knowledge of the nanotoxicity of cutting-edge 2D materials on human health, thereby advancing their potential biological applications.

The Roadmap of Graphene-Based Sensors: Electrochemical Methods for Bioanalytical Applications

Graphene (GR) has engrossed immense research attention as an emerging carbon material owing to its enthralling electrochemical (EC) and physical properties. Herein, we debate the role of GR-based nanomaterials (NMs) in refining EC sensing performance toward bioanalytes detection. Following the introduction, we briefly discuss the GR fabrication, properties, application as electrode materials, the principle of EC sensing system, and the importance of bioanalytes detection in early disease diagnosis. Along with the brief description of GR-derivatives, simulation, and doping, classification of GR-based EC sensors such as cancer biomarkers, neurotransmitters, DNA sensors, immunosensors, and various other bioanalytes detection is provided. The working mechanism of topical GR-based EC sensors, advantages, and real-time analysis of these along with details of analytical merit of figures for EC sensors are discussed. Last, we have concluded the review by providing some suggestions to overcome the existing downsides of GR-based sensors and future outlook. The advancement of electrochemistry, nanotechnology, and point-of-care (POC) devices could offer the next generation of precise, sensitive, and reliable EC sensors.

A scientometric study on application of electrochemical sensors for detection of pesticide using graphene-based electrode modifiers

Pesticide testing is an important topic in environmental protection and food safety. The development of green, accurate and reliable pesticide residue detection methods is an important technical support for implementing of agricultural quality supervision. Electrochemical sensors are a very promising analytical method for pesticide detection due to their high sensitivity, speed, low cost and portability. Performance enhancement of electrochemical sensors is often accompanied by research advances in materials science. Among them, carbon material is a very important electrode material for the fabrication of electrochemical sensors. The discovery of graphene makes it the most promising candidate among carbon materials for sensor performance enhancement. The topic of this review is the use of graphene-modified electrochemical sensors for pesticide detection in the last decade. Traditional literature summaries and bibliometric analyses were used for an in-depth analysis of this topic. In addition to the introduction of different sensor types and performance comparisons, this review also parses the authors' country, keywords and publication frequency. The related research experienced rapid growth several years ago and has now reached a relatively stable stage. We also discuss the perspectives on this topic.

Phytofabricated Nanoparticle Formulation for Cancer Treatment: A Comprehensive Review

In recent times, nanotechnology has made significant advances in the field of cancer. The majority of chemotherapeutic drugs do not selectively target cancer cells, and they might cause side effects and damage to healthy cells, resulting in a variety of adverse effects. Having a thorough understanding of nanoparticles may improve drug targeting and administration. The nano-engineering of pharmacological and natural compounds can improve the diagnosis and treatment. Polymeric micelles, liposomes, and dendrimers are examples of innovative cancer therapeutic nano-formulations. It has been demonstrated that quantum dots, nano-suspensions, and gold nanoparticles can improve drug delivery. Nanomedicines may be delivered more effectively, focusing on cancerous cells instead of healthy tissues, which minimizes undesirable side effects and drug resistance to chemotherapeutic agents. However, limited water solubility, low stability, poor absorption, and quick metabolism limit their therapeutic effectiveness. Nanotechnology has generated unique formulations to optimise the potential use of phytochemicals in anticancer therapy. Nanocomposites can improve phytochemical solubility and bioavailability, extend their half-life in circulation, and even transport phytochemicals to specific locations. The progress in using phytochemical-based nanoparticles in cancer treatment is summarized in this paper.

Ultraviolet graphene ultranarrow absorption engineered by lattice plasmon resonance

We numerically demonstrate an ultraviolet graphene ultranarrow absorption in a hybrid graphene-metal structure. The full-width at half maximum of the absorption band being 9 nm in ultraviolet range is achieved based on the coupling of lattice plasmon resonances of the metallic nanostructure to the optical dissipation of graphene. The position, absorbance and linewidth of the hybridized narrow resonant mode tuned by controlling geometrical parameters and materials are systematically investigated. The proposed structure possesses high refractive index sensitivity of 288 nm/RIU and figure of merit of 72, and can also be used to detect small molecules layer of sub-nanometer thickness and refractive index with small changes, providing promising applications in ultra-compact efficient biosensors.

A novel electrochemical immunosensor for the sensitive detection of tiamulin based on staphylococcal protein A and silver nanoparticle-graphene oxide nanocomposites

Tiamulin (TML) is a pleuromutilin antibiotic and mainly used to treat pulmonary and gastrointestinal infections. However, excessive use of TML can bring health threats to consumers. In this work, a label-free electrochemical immunosensor was proposed for sensitive detection of TML in pork and pork liver. Silver nanoparticles (AgNPs) were synthesized in situ on graphene oxide (GO), in which GO acted as a carrier for loading more AgNPs and AgNPs exhibited both strong conductivity and good redox property. In addition, staphylococcal protein A (SPA) was applied to oriented immobilization of fragment crystallizable (Fc) region of the TML monoclonal antibody. Under the optimal condition, the developed electrochemical immunosensor exhibited a good linear response with a concentration of TML ranging from 0.05 ng mL^-1 to 100 ng mL^-1 and the limit of detection (LOD) was 0.04 ng mL^-1. Furthermore, the designed immunosensor was applied to detect TML in real samples with a good accuracy. Therefore, the label-free electrochemical immunosensor could be used as a potential method to detect TML and other antibiotic residues in animal derived foods.

Adsorption, Gas-Sensing, and Optical Properties of Molecules on a Diazine Monolayer: A First-Principles Study

Using first-principles calculations, the structural, electronic, and optical properties of CO2, CO, N2O, CH4, H2, N2, O2, NH3, acetone, and ethanol molecules adsorbed on a diazine monolayer were studied to develop the application potential of the diazine monolayer as a room-temperature gas sensor for detecting acetone, ethanol, and NH3. We found that these molecules are all physically adsorbed on the diazine monolayer with weak adsorption strength and charge transfer between the molecules and the monolayer, but the physisorption of only NH3, acetone, and ethanol remarkably modified the electronic properties of the diazine monolayer, especially for the obvious change in electric conductivity, showing that the diazine monolayer is highly sensitive to acetone, NH3, and ethanol. Further, the adsorption of NH3, acetone, and ethanol molecules remarkably modifies, in varying degrees, the optical properties of the diazine monolayer, such as work function, absorption coefficient, and the reflectivity, whereas adsorption of other molecules has infinitesimal influence. The different adsorption behaviors and influences of the electronic and optical properties of molecules on the monolayer show that the diazine monolayer has high selectivity to NH3, acetone, and ethanol. The recovery time of NH3, acetone, and ethanol molecules is, respectively, 1.2 μs, 7.7 μs, and 0.11 ms at 300 K. Thus, the diazine monolayer has a high application potential as a room-temperature acetone, ethanol, and NH3 sensor with high performance (high selectivity and sensitivity, and rapid recovery time).

PEGylated DOX-coated nano graphene oxide as pH-responsive multifunctional nanocarrier for targeted drug delivery

Nano graphene oxide (NGO) has high drug-loading capacity due to its huge surface area. However, the limited stability and the poor biocompatibility of NGO hampered its application as drug delivery carrier under physiological conditions. Thereby, a new strategy of using chemical conjugation on NGO with hydrophilic polymers was adopted but currently was too complicated, low yield and costly. In this study, doxorubicin-hyd-PEG-folic acid (DOX-hyd-PEG-FA) polymers were coated on the surface of NGO via π-π stocking and the hydrophobic effect between DOX and NGO. With the PEG shell protection, the biocompatibility of NGO was significantly improved. The drug-loading capacity of nanoparticles was more than 100%. FA ligands on the nanoparticle could guide the nanoparticles actively targeting to tumour cells. The hydrazone bond between DOX and PEG was decomposed spontaneously in the weakly acidic environment, which made PEG layer dissociated from NGO. Furthermore, DOX was easily protonized at low pH conditions, which weakened the interaction between DOX and NGO. Thus, DOX could be released rapidly from the nanoparticles in tumour cells. In summary, NGO@DOX-hyd-PEG-FA is an easy-prepared nanoparticle with excellent biocompatibility, high pH-sensitivity and active tumour targeting. Therefore, it is a promising multifunctional nanocarrier effective for targeted drug delivery.