A Review on Graphene Oxide Two-dimensional Macromolecules: from Single Molecules to Macro-assembly

Functionalized graphene oxide as a nanocarrier for delivering oridonin to improve anti-breast cancer cell activity

In this study, a targeted nanocarrier was developed by functionalizing graphene oxide with polyethyleneimine and folic acid, intended for loading oridonin. The nanocarrier was successfully synthesized and characterized using an ultraviolet spectrum, Fourier transform infrared spectroscopy and scanning electron microscopy. The nanocarrier demonstrated a remarkable oridonin loading capacity, reaching 424.8 μg/mg, as determined by ultra-high performance liquid chromatography. In vitro drug release experiments exhibited a pH-dependent release profile, with a higher cumulative release in an acidic environment. The release mechanism followed the Ritger-Peppas equation model. Cytotoxicity assays indicated minimal toxicity of the nanocarrier. Enhanced cellular uptake by MCF7 cells was observed for carriers functionalized with folate and polyethyleneimine. These findings highlight the potential of functionalized graphene oxide as a promising carrier for oridonin delivery in biomedical applications.

Plasmonic Terahertz Devices and Sensors Based on Carbon Electronics

Tunable terahertz (THz) photonic devices are imperative in a wide range of applications ranging from THz signal modulation to molecular sensing. One of the currently prevailing methods is based on arrays of metallic or dielectric resonators integrated with functional materials in response to an external stimulus, in which for the purpose of sensing the external stimuli may introduce inadvertent undesirable effects into the target samples to be measured. Here we developed an alternative approach by postprocessing nanothickness macro-assembled graphene (nMAG) films with widely tunable THz conductivity, enabling versatile solid-state THz devices and sensors, showing multifunctional nMAG-based applications. The THz conductivities of free-standing nMAGs showed a broad range from 1.2 × 10³ S/m in reduced graphene oxide before annealing to 4.0 × 10⁶ S/m in a nMAG film annealed at 2800 °C. We fabricated nMAG/dielectric/metal and nMAG/dielectric/nMAG THz Salisbury absorbers with broad reflectance ranging from 0% to 80%. The highly conductive nMAG films enabled THz metasurfaces for sensing applications. Taking advantage of the resonant field enhancement arising from the plasmonic metasurface structures and the strong interactions between analyte molecules and nMAG films, we successfully detected diphenylamine with a limit of detection of 4.2 pg. Those wafer-scale nMAG films present promising potential in high-performance THz electronics, photonics, and sensors.

Theoretical Study on the Aggregation and Adsorption Behaviors of Anticancer Drug Molecules on Graphene/Graphene Oxide Surface

Graphene and its derivatives are frequently used in cancer therapy, and there has been widespread interest in improving the therapeutic efficiency of targeted drugs. In this paper, the geometrical structure and electronic effects of anastrozole(Anas), camptothecin(CPT), gefitinib (Gefi), and resveratrol (Res) on graphene and graphene oxide(GO) were investigated by density functional theory (DFT) calculations and molecular dynamics (MD) simulation. Meanwhile, we explored and compared the adsorption process between graphene/GO and four drug molecules, as well as the adsorption sites between carriers and payloads. In addition, we calculated the interaction forces between four drug molecules and graphene. We believe that this work will contribute to deepening the understanding of the loading behaviors of anticancer drugs onto nanomaterials and their interaction.

Unraveling the morphological complexity of two-dimensional macromolecules

2D macromolecules, such as graphene and graphene oxide, possess a rich spectrum of conformational phases. However, their morphological classification has only been discussed by visual inspection, where the physics of deformation and surface contact cannot be resolved. We employ machine learning methods to address this problem by exploring samples generated by molecular simulations. Features such as metric changes, curvature, conformational anisotropy and surface contact are extracted. Unsupervised learning classifies the morphologies into the quasi-flat, folded, crumpled phases and interphases using geometrical and topological labels or the principal features of the 2D energy map. The results are fed into subsequent supervised learning for phase characterization. The performance of data-driven models is improved notably by integrating the physics of geometrical deformation and topological contact. The classification and feature extraction characterize the microstructures of their condensed phases and the molecular processes of adsorption and transport, comprehending the processing-microstructures-performance relation in applications.

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Morphology of 2D macromolecules are classified into four phases

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Data-driven models capture physics and topology beyond the geometry

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Condensed-phase properties are understood by the features extracted

Resolving morphological complexity of macromolecules is the stepping stone to the design and fabrication of high-performance, multi-functional materials and to understanding the soft matter behaviors in biology and engineering. To extract the physics of lattice distortion and surface contact beyond the conformation is critical, yet challenging. Here, we show that, by labeling the simulation data using the 2D map of potential energies, the 3D geometry, and the topology of contact, morphological classification can be achieved with high accuracy. The well-trained model can be used to decipher the microstructural complexity using simulation or experimental data, which may include the geometrical representation only. This data-driven approach extracts the key geometrical and topological features of 2D macromolecules that are directly responsible for the material performance in relevant applications and can be extended to study other complex surfaces such as red blood cells and the brain.

Recent Advances in Fluorinated Graphene from Synthesis to Applications: Critical Review on Functional Chemistry and Structure Engineering

Fluorinated graphene (FG), as an emerging member of the graphene derivatives family, has attracted wide attention on account of its excellent performances and underlying applications. The introduction of a fluorine atom, with the strongest electronegativity (3.98), greatly changes the electron distribution of graphene, resulting in a series of unique variations in optical, electronic, magnetic, interfacial properties and so on. Herein, recent advances in the study of FG from synthesis to applications are introduced, and the relationship between its structure and properties is summarized in detail. Especially, the functional chemistry of FG has been thoroughly analyzed in recent years, which has opened a universal route for the functionalization and even multifunctionalization of FG toward various graphene derivatives, which further broadens its applications. Moreover, from a particular angle, the structure engineering of FG such as the distribution pattern of fluorine atoms and the regulation of interlayer structure when advanced nanotechnology gets involved is summarized. Notably, the elaborated structure engineering of FG is the key factor to optimize the corresponding properties for potential applications, and is also an up-to-date research hotspot and future development direction. Finally, perspectives and prospects for the problems and challenges in the study of FG are put forward.

Multifunctional Macroassembled Graphene Nanofilms with High Crystallinity

A "cooling-contraction" method to separate large-area (up to 4.2 cm in lateral size) graphene oxide (GO)-assembled films (of nanoscale thickness) from substrates is reported. Heat treatment at 3000 °C of such free-standing macroscale films yields highly crystalline "macroassembled graphene nanofilms" (nMAGs) with 16-48 nm thickness. These nMAGs present tensile strength of 5.5-11.3 GPa (with ≈3 µm gauge length), electrical conductivity of 1.8-2.1 MS m^-1 , thermal conductivity of 2027-2820 W m^-1 K^-1 , and carrier relaxation time up to ≈23 ps. As a demonstration application, an nMAG-based sound-generator shows a 30 µs response and sound pressure level of 89 dB at 1 W cm^-2 . A THz metasurface fabricated from nMAG has a light response of 8.2% for 0.159 W mm^-2 and can detect down to 0.01 ppm of glucose. The approach provides a straightforward way to form highly crystallized graphene nanofilms from low-cost GO sheets.

Hydroplastic Micromolding of 2D Sheets

Processing 2D sheets into desired structures with high precision is of great importance for fabrication and application of their assemblies. Solution processing of 2D sheets from dilute dispersions is a commonly used method but offers limited control over feature size precision owing to the extreme volume shrinkage. Plastic processing from the solid state is therefore a preferable approach to achieve high precision. However, plastic processing is intrinsically hampered by strong interlayer interactions of the 2D sheet solids. Here, a hydroplastic molding method to shape layered solids of 2D sheets with micrometer-scale precision under ambient conditions is reported. The dried 2D layered solids are plasticized by intercalated solvents, affording plastic near-solid compounds that enable local plastic deformation. Such an intercalated solvent-induced hydroplasticity is found in a broad family of 2D materials, for example graphene, MoS₂ , and MXene. The hydroplastic molding enables fabrication of complex spatial structures (knurling, origami) and microimprinted tubular structures down to diameters of 390 nm with good fidelity. The method enhances the structural accuracy and enriches the structural diversity of 2D macroassemblies, thus providing a feasible strategy to tune their electrical, optical, and other functional properties.