Density functional theory calculations and molecular dynamics simulations of the adsorption of biomolecules on graphene surfaces

Preparation and sustained-release mechanism of hydroxybutyl chitosan/graphene oxide temperature-sensitive hypoglycaemic subcutaneous implants

The current situation of diabetes prevention and control is extremely severe. For instance, glimepiride (GLM), a third-generation sulfonylurea, demonstrates suboptimal clinical efficacy in oral dosage forms, which underscores the pressing need for the development of a new dosage form. Recently, in situ gel subcutaneous implants have garnered considerable attention. Hydroxybutyl chitosan (HBC) can spontaneously crosslink to form a thermosensitive hydrogel and has good biocompatibility. However, its application is hindered by its limited mechanical properties. Graphene oxide (GO), known for its stable dispersion in water, can load GLM through π-π stacking interactions. When combined with HBC, GO enhances the mechanical properties and stability of the hydrogel. Therefore, an HBC-GO@GLM hydrogel was prepared. Rheological analysis revealed that the incorporation of GO increased the critical gelation temperature of the 5 wt% HBC hydrogel from 19.1°C to 27.2°C, considerably enhancing the mechanical properties of the hydrogel. Using encapsulation efficiency as an evaluation index, the optimal encapsulation efficiency of GO@GLM was determined to be 73.53% ± 0.45% with a drug loading capacity of 27.39 ± 0.17% using the Box-Behnken design model. Computer simulation technology validated the interaction between the materials and the drug release mechanism. Pharmacokinetic results showed that compared to the HBC@GLM group, the half-life (t1/2), mean residence time and the area under the curve for the HBC-GO@GLM group were approximately 3 times those of the HBC@GLM group. Subcutaneous implantation of the HBC-GO@GLM hydrogel for drug delivery considerably extended the drug's action time in the body, thereby maintaining blood sugar levels within a normal and stable range for an extended period.

Role of Molecular, Crystal, and Surface Chemistry in Directing the Crystallization of Entacapone Polymorphs on the Au(111) Template Surface

The pharmaceutical compound entacapone ((E)-2-cyano-3-(3,4-dihydroxy-5-nitrophenyl)-N,N-diethylprop-2-enamide) is important in the treatment of Parkinson's disease, exhibiting interesting polymorphic behavior upon crystallization from solution. It consistently produces its stable form A with a uniform crystal size distribution on the surface of an Au(111) template while concomitantly forming its metastable form D within the same bulk solution. Molecular modeling using empirical atomistic force-fields reveals more complex molecular and intermolecular structures for form D compared to form A, with the crystal chemistry of both polymorphs being dominated by van der Waals and π-π stacking interactions with lower contributions (ca. 20%) from hydrogen bonding and electrostatic interactions. Comparative lattice energies and convergence for the polymorphs are consistent with the observed concomitant polymorphic behavior. Synthon characterization reveals an elongated needle-like morphology for form D crystals in contrast to the more equant form A crystals with the surface chemistry of the latter exposing the molecules' cyano groups on its {010} and {011} habit faces. Density functional theory modeling of surface adsorption reveals preferential interactions between Au and the synthon G_A interactions of form A on the Au surface. Molecular dynamics modeling of the entacapone/gold interface reveals the entacapone molecular structure within the first adsorbed layer to show nearly identical interaction distances, for both the molecules within form A or D with respect to the Au surface, while in the second and third layers when entacapone molecule-molecule interactions overtake the interactions between those of molecule-Au, the intermolecular structures are found to be closer to the form A structure than form D. In these layers, synthon G_A (form A) could be reproduced with just two small azimuthal rotations (5° and 15°) whereas the closest alignment to a form D synthon requires larger azimuthal rotations (15° and 40°). The cyano functional group interactions with the Au template dominate interfacial interactions with these groups being aligned parallel to the Au surface and with nearest neighbor distances to Au atoms more closely matching those in form A than form D. The overall polymorph direction pathway thus encompasses consideration of molecular, crystal, and surface chemistry factors.

In Silico Study of Novel Cyclodextrin Inclusion Complexes of Polycaprolactone and Its Correlation with Skin Regeneration

Three novel biomaterials obtained via inclusion complexes of β-cyclodextrin, 6-deoxi-6-amino-β-cyclodextrin and epithelial growth factor grafted to 6-deoxi-6-amino-β-cyclodextrin with polycaprolactone. Furthermore, some physicochemical, toxicological and absorption properties were predicted using bioinformatics tools. The electronic, geometrical and spectroscopical calculated properties agree with the properties obtained via experimental methods, explaining the behaviors observed in each case. The interaction energy was obtained, and its values were -60.6, -20.9 and -17.1 kcal/mol for β-cyclodextrin/polycaprolactone followed by the 6-amino-β-cyclodextrin-polycaprolactone complex and finally the complex of epithelial growth factor anchored to 6-deoxy-6-amino-β-cyclodextrin/polycaprolactone. Additionally, the dipolar moments were calculated, achieving values of 3.2688, 5.9249 and 5.0998 Debye, respectively, and in addition the experimental wettability behavior of the studied materials has also been explained. It is important to note that the toxicological predictions suggested no mutagenic, tumorigenic or reproductive effects; moreover, an anti-inflammatory effect has been shown. Finally, the improvement in the cicatricial effect of the novel materials has been conveniently explained by comparing the poly-caprolactone data obtained in the experimental assessments.

Combined computational and experimental study about the incorporation of phosphorus into the structure of graphene oxide

Phosphorus-containing graphene-based hybrids are materials with outstanding properties for diverse applications. In this work, an easy route to produce phosphorus-graphene oxide hybrid materials is described, involving the use of variable amounts of H₃PO₄ and H₂SO₄ during the reaction of oxidation of a graphitic precursor. The physical and chemical features of the hybrids change significantly with the variation in the acid amounts used in the syntheses. XPS and solid-state ¹³C and ³¹P NMR results show that the hybrids contain large amounts of oxygen functional groups, with the phosphorus incorporation proceeding mostly through the formation of phosphate-like linkages and other functions with C-O-P bonds. The experimental findings are supported by DFT calculations, which allow the assessment of the energetics and the geometry of the interaction between phosphate groups and graphene-based models; these calculations are also used to predict the chemical shifts in the ³¹P and ¹³C NMR spectra of the models, which show good agreement with the experimentally observed solid-state NMR spectra.

Effect of Hydroxylation and Carboxylation on the Catalytic Activity of Fe2O3/Graphene for Oxidative Desulfurization and Denitration

Iron-based particles loaded on porous carbon materials have attracted extensive attention as catalysts for denitration and desulfurization reactions. However, the carbon support of a high-temperature denitration catalyst is inevitably oxidized in the presence of H2O and O2. The mechanism of denitration catalyst oxidation and its influence on the catalytic reaction remain to be further explored. Fe2O3-loaded graphene models with carbon vacancy (Gdef), hydroxyl (HyG), and carboxyl (CyG) were constructed to investigate the effects of hydroxylation and carboxylation on the catalytic activity of Fe2O3/graphene for oxidative desulfurization and denitration by using density functional theory (DFT) calculations. According to the analysis of structural properties and adsorption energy, the adsorption process of Fe2O3 on HyG and CyG was observed to have proceeded more favorably than that on Gdef. The density-of-states (DOS) results also affirmed that HyG and CyG promote the electron delocalization of Fe2O3 around the Fermi level, enhancing the chemical activity of Fe2O3. Moreover, adsorption energy analysis indicates that hydroxylation and carboxylation enhanced the adsorption of SO2 and H2O2 on Fe2O3/graphene while also maintaining preferable adsorption stability of NO. Furthermore, mechanistic research explains that adsorbed H2O2 on HyG and CyG directly oxidizes NO and SO2 into HNO2 and H2SO4 following a one-step reaction. The results provide a fundamental understanding of the oxidized catalyst on catalytic denitration and desulfurization reactions.

Biomaterialomics: Data science-driven pathways to develop fourth-generation biomaterials

Conventional approaches to developing biomaterials and implants require intuitive tailoring of manufacturing protocols and biocompatibility assessment. This leads to longer development cycles, and high costs. To meet existing and unmet clinical needs, it is critical to accelerate the production of implantable biomaterials, implants and biomedical devices. Building on the Materials Genome Initiative, we define the concept 'biomaterialomics' as the integration of multi-omics data and high-dimensional analysis with artificial intelligence (AI) tools throughout the entire pipeline of biomaterials development. The Data Science-driven approach is envisioned to bring together on a single platform, the computational tools, databases, experimental methods, machine learning, and advanced manufacturing (e.g., 3D printing) to develop the fourth-generation biomaterials and implants, whose clinical performance will be predicted using 'digital twins'. While analysing the key elements of the concept of 'biomaterialomics', significant emphasis has been put forward to effectively utilize high-throughput biocompatibility data together with multiscale physics-based models, E-platform/online databases of clinical studies, data science approaches, including metadata management, AI/ Machine Learning (ML) algorithms and uncertainty predictions. Such integrated formulation will allow one to adopt cross-disciplinary approaches to establish processing-structure-property (PSP) linkages. A few published studies from the lead author's research group serve as representative examples to illustrate the formulation and relevance of the 'Biomaterialomics' approaches for three emerging research themes, i.e. patient-specific implants, additive manufacturing, and bioelectronic medicine. The increased adaptability of AI/ML tools in biomaterials science along with the training of the next generation researchers in data science are strongly recommended. STATEMENT OF SIGNIFICANCE: This leading opinion review paper emphasizes the need to integrate the concepts and algorithms of the data science with biomaterials science. Also, this paper emphasizes the need to establish a mathematically rigorous cross-disciplinary framework that will allow a systematic quantitative exploration and curation of critical biomaterials knowledge needed to drive objectively the innovation efforts within a suitable uncertainty quantification framework, as embodied in 'biomaterialomics' concept, which integrates multi-omics data and high-dimensional analysis with artificial intelligence (AI) tools, like machine learning. The formulation of this approach has been demonstrated for patient-specific implants, additive manufacturing, and bioelectronic medicine.

Curcumin and Graphene Oxide Incorporated into Alginate Hydrogels as Versatile Devices for the Local Treatment of Squamous Cell Carcinoma

With the aim of preparing hybrid hydrogels suitable for use as patches for the local treatment of squamous cell carcinoma (SCC)-affected areas, curcumin (CUR) was loaded onto graphene oxide (GO) nanosheets, which were then blended into an alginate hydrogel that was crosslinked by means of calcium ions. The homogeneous incorporation of GO within the polymer network, which was confirmed through morphological investigations, improved the stability of the hybrid system compared to blank hydrogels. The weight loss in the 100–170 °C temperature range was reduced from 30% to 20%, and the degradation of alginate chains shifted to higher temperatures. Moreover, GO enhanced the stability in water media by counteracting the de-crosslinking process of the polymer network. Cell viability assays showed that the loading of CUR (2.5% and 5% by weight) was able to reduce the intrinsic toxicity of GO towards healthy cells, while higher amounts were ineffective due to the antioxidant/prooxidant paradox. Interestingly, the CUR-loaded systems were found to possess a strong cytotoxic effect in SCC cancer cells, and the sustained CUR release (~50% after 96 h) allowed long-term anticancer efficiency to be hypothesized.

Adsorption of sulfamethoxazole and sulfadiazine on phosphorus-containing stalk cellulose under different water pH studied by quantitative evaluation

To improve the high-value application of corn stalk, phosphorus-containing stalk cellulose (PFC) was prepared, characterized, and utilized for the adsorption of sulfamethoxazole (SMZ) and sulfadiazine (SD), with maximum adsorption capacities of 1.385 and 2.527 mg/g at pH 7. As expected, the adsorption efficiency of PFC was strongly affected by pH, and the preferential adsorption order of SMZ^- (SD⁰) > SMZ⁰ (SD^-) > SMZ⁺ (SD⁺) was obtained from the experimental results and due to the charges of PFC and the SMZ and SD species. Furthermore, these results were qualitatively linked to the adsorption mechanism, e.g., π⁺-π electron donor-acceptor (EDA), anion-π bond electrostatic, and hydrophobic interactions. In particular, the adsorption mechanism was further characterized in terms of structure and analyzed systematically using density functional theory (DFT), frontier orbital theory (FOT), and molecular dynamics (MD) simulation, with the aim to explain the theoretical calculation and experimental results. As a result, the highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) orbitals revealed the key role of the rings and functional groups of PFC and SMZ (or SD) and validated the optimized structures of PFC⁺ sulfonamides (SAs)⁺, PFC^- SAs⁰, and PFC^- SAs^-, in which their binding energy values, energy gaps, and relevant molecular lengths determined their stability. Additionally, the van der Waals (vdW) energy confirmed the effect of various interactions on adsorption.

Recent advances in computational methods for biosensor design

Biosensors are analytical tools with a great application in healthcare, food quality control, and environmental monitoring. They are of considerable interest to be designed by using cost-effective and efficient approaches. Designing biosensors with improved functionality or application in new target detection has been converted to a fast-growing field of biomedicine and biotechnology branches. Experimental efforts have led to valuable successes in the field of biosensor design; however, some deficiencies restrict their utilization for this purpose. Computational design of biosensors is introduced as a promising key to eliminate the gap. A set of reliable structure prediction of the biosensor segments, their stability, and accurate descriptors of molecular interactions are required to computationally design biosensors. In this review, we provide a comprehensive insight into the progress of computational methods to guide the design and development of biosensors, including molecular dynamics simulation, quantum mechanics calculations, molecular docking, virtual screening, and a combination of them as the hybrid methodologies. By relying on the recent advances in the computational methods, an opportunity emerged for them to be complementary or an alternative to the experimental methods in the field of biosensor design.

Understanding Adsorption Behaviors of Organic Friction Modifiers on Hydroxylated SiO2 (001) Surfaces: Effects of Molecular Polarity and Temperature

Molecular dynamics simulations are used to investigate the physisorption of organic friction modifiers (OFMs) lubricated by 1-decene trimer (PAO4) representing a base oil and confined between hydroxylated SiO₂ (001) surfaces. The results indicate that OFM molecules form dense, tendentiously vertical monolayer films at low temperature but loose adsorption layers at high temperature, particularly for R-NH₂ with weaker molecular polarity. The structural information is quantitatively clarified by mass density profiles, radial distribution function, and probability distributions of an end-to-end distance at a perpendicular-to-surface direction. The movement performance of lubricant, reflected by the thickness of the organic part and radius of gyration of PAO4 molecules, strongly depends on temperature. The adsorption amount of OFM molecules decreases dramatically with lowering OFM polarity and increasing temperature above the critical desorption temperatures of about 320, 373, and 453 K for amine (R-NH₂), alcohol (R-OH), and acid (R-COOH), respectively. The interaction energies of the OFM-surface decrease continuously for the R-NH₂ system with temperature and decrease rapidly as temperature exceeds a critical value for both R-OH and R-COOH systems. The single-molecule geometry optimization validates the significant role of the electrostatic and hydrogen-bond attractions in molecular adsorption. Therefore, the OFMs with stronger polarity (like R-COOH) present stronger adsorption and better temperature resistance. The findings in this work are of particular value and provide a guideline in designing and engineering novel OFM additives for extreme lubrication conditions.

Predictions of Pattern Formation in Amino Acid Adlayers at the In Vacuo Graphene Interface: Influence of Termination State

Controlled self-assembly of biomolecules on graphene offers a pathway for realizing its full potential in biological applications. Microscopy has revealed the self-assembly of amino acid adlayers into dimer rows on nonreactive substrates. However, neither the spontaneous formation of these patterns, nor the influence of amino acid termination state on the formation of patterns has been directly resolved to date. Molecular dynamics simulations, with the ability to reveal atomic level details and exert full control over the termination state, are used here to model initially disordered adlayers of neutral, zwitterionic, and neutral-zwitterionic mixtures for two types of amino acids, tryptophan and methionine, adsorbed on graphene in vacuo. The simulations of the zwitterion-containing adlayers exhibit the spontaneous emergence of dimer row ordering, mediated by charge-driven intermolecular interactions. In contrast, adlayers containing only neutral species do not assemble into ordered patterns. It is also found that the presence of trace amounts of water reduces the interamino acid interactions in the adlayers, but does not induce or disrupt pattern formation. Overall, the findings reveal the balance between the lateral interamino acid interactions and amino acid-graphene interactions, providing foundational insights for ultimately realizing the predictable pattern formation of biomolecules adsorbed on unreactive surfaces.

Separation and preconcentration of arsenite and other heavy metal ions using graphene oxide laminated with protein molecules

The graphene oxide surface was laminated with bovine serum albumin (BSA) followed by the directional flow through a membrane to prepare a free-standing PLGO (protein laminated GO) composite. BSA immobilization increased the interlayer spacing of GO and led to the formation of capillaries. The column packed with PLGO adsorbent permeated water faster as much as ca. 5 fold as compared to only GO packed column. The PLGO composite was used to develop a solid phase extraction method for the selective preconcentration of As(III) in the presence of As(V), prior to their determination. As(III) binding to sulfhydryl groups of BSA in PLGO plays a key role in the speciation. The coexisting heavy metal ions did not hinder the recovery of trace As(III). The method was advantageously employed for the preconcentration of As(III), Pb(II), Cd(II), Zn(II), Cu(II) and Ni(II) from water and food samples. A 3 mL of 1 M hydrochloric acid would be adequate for the complete desorption (recovery > 99%) of the adsorbed metal ions. The preconcentration limit achieved for As(III), Pb(II), Cd(II), Zn(II), Cu(II) and Ni(II) were 1.7, 2.0, 2.0, 2.0, 1.8 and 2.0 μg L^-1 respectively, with an optimized sample flow rate of 10 mL min^-1.

Molecular dynamics simulations of loading and unloading of drug molecule bortezomib on graphene nanosheets

Graphene-drug complexes can enter the lipid bilayer and then drug molecules release from graphene surface.

Establishing the accuracy of density functional approaches for the description of noncovalent interactions in biomolecules

Biomolecules have complex structures, and noncovalent interactions are crucial to determine their conformations and functionalities.

Strain-tunable CO2 storage by black phosphorene and α-PC from combined first principles and molecular dynamics studies

2D layered materials are intrinsically promising mediums for gas adsorption because of their recognized large surface areas and structural stability. Their gas adsorption and desorption processes are usually controlled by changing the temperature or applying high voltage. In this work, though combined density functional theory (DFT) calculations and molecular dynamics (MD) simulations, we propose that external tensile strain can also regulate the gas binding energetics and kinetics using two representative 2D materials, monolayer black phosphorene (BP) and black phosphorus carbide (α-PC), as showpiece models. The DFT results clearly show that CO2 can be physically adsorbed on BP/α-PC with moderate binding strength, which facilities the adsorption and desorption processes. For BP, strain increases the storage capacity from 10.90 ± 0.28 mmol g-1 (strain free) to 12.67 ± 0.33 (30% strain) with a tunability of 16.2%. α-PC, however, has a smaller strain response; its CO2 storage capacity increases from 15.98 ± 0.34 mmol g-1 (strain free) to 17.15 ± 0.36 mmol g-1 for a 10% strained state. DFT calculations reveal that CO2 is an electron acceptor for both BP and α-PC; however, it hardly regulates their electronic structures. The theoretical investigations suggest that BP and α-PC have great potential as gas capture and storage materials. The strain controlling approach can be generalized for the design of tunable nano-devices by external mechanical stimuli.

Theoretical Study of the Adsorption Process of Antimalarial Drugs into Acrylamide-Base Hydrogel Model Using DFT Methods: The First Approach to the Rational Design of a Controlled Drug Delivery System

The interaction between three widely used antimalarial drugs chloroquine, primaquine and amodiaquine with acrylamide dimer and trimer as a hydrogel model, were studied by means of density functional theory calculation in both vacuum and water environments, using the functional wb97xd with 6-31++G(d,p) basis set and polarizable continuum model (C-PCM) of solvent. According to binding energy, around −3.15 to −11.91 kJ/mol, the interaction between antimalarial compounds and hydrogel model are exothermic in nature. The extent of interaction found is primaquine > amodiaquine > chloroquine. The natural bond orbital (NBO) calculation and application of second-order perturbation theory show strong charge transfer between the antimalarial and hydrogel model. In addition, the results suggest these interactions are polar in nature, where hydrogen bonds play a principal role in stabilization of the complex. Comparing with the gas-phase, the complexes in the water environment are also stable, with suitable values of Log P (Partition coefficient), and dipolar momentum. Consequently, these results encourage to test acrylamide hydrogels as antimalarial delivery systems.

Explaining the interactions between metaldehyde and acidic surface groups of activated carbon under different pH conditions

Metaldehyde (MA) is an organic compound widely used in agriculture all around the world as molluscicide. There are growing concerns that relatively high levels of MA have been detected in surface water, which could be ascribed to the fact that it is transparent to common wastewater treatment processes. A theoretical study of the influence of activated carbon (AC) surface groups (SGs) on MA adsorption is done in order to help to understand the process and to evaluate the influence of the acid SGs over the adsorption in AC filters. Multiple Minima Hypersurface methodology was employed in order to study the interactions of the MA with acid SGs (hydroxyl and carboxyl) at acidic and neutral pH, and at different hydration conditions explicitly taking into account the solvent influence. Selected structures were re-optimized using Density Functional Theory and posteriorly refined to achieve a well-defined electron density to characterize the interactions by the Quantum Theory of Atoms in Molecules approach. The obtained results showed that the presence of SGs enhances the adsorption process. The deprotonated carboxyl and hydroxyl SGs of AC models show the strongest interactions, suggesting greater adsorption at neutral pH which is in concordance with experimental data. The main interactions are of a dispersive nature between the pesticide and the π-cloud of the AC and hydrogen bonds between the MA and the acid SGs suggesting that the adsorption process is driven by a physisorption mechanism. Water acts as an intermediary between the AC and MA and competing with it for the adsorption sites.

Application of molecular dynamics simulation to improve the theoretical prediction for collisional cross section of aromatic compounds with long alkyl chains in crude oils

RATIONALE

Molecular dynamics (MD) simulations with finite temperature were performed to improve the theoretical prediction of collisional cross section (CCS) values, especially for aromatic compounds containing long alkyl chains.

METHODS

In this study, the CCS values of 11 aromatic compounds with long alkyl chains were calculated by MD simulations while considering internal energy at 300, 500, and 700 K, and the results were compared with experimentally determined values.

RESULTS

The CCS values calculated at higher energies showed better agreement with the experimental values. Polycyclic aromatic hydrocarbons (PAHs) such as pentacene and benz[b]anthracene were also investigated, and better agreement between the theoretical and experimental results was observed when higher temperature (or higher internal energy) was considered.

CONCLUSIONS

The data presented in this study show that the internal degrees of freedom of ions must be considered to accurately predict the CCS values of aromatic compounds with a flexible structure measured by ion mobility mass spectrometry.

Stability, Cellular Uptake, and in Vivo Tracking of Zwitterion Modified Graphene Oxide as a Drug Carrier

In this paper, a novel kind of zwitterion modified graphene oxide (GO) for promoting stability and reducing aggregation of GO as a drug carrier was proposed and demonstrated. Specifically, the GO was functionalized with a kind of zwitterion based silane, 3-(dimethyl(3-(trimethoxysilyl)propyl)-ammonio)propane-1-sulfonate (SBS). After zwitterion modification, the SBS functionalized GO (GO-SB) shows significantly enhanced stability in both serum-free and serum-containing solution, especially after loading doxorubicin hydrochloride (DOX). According to drug release profiles, the drug-loaded GO-SB exhibits thermosensitive and sustained release behavior. Meanwhile, in vitro studies show that the DOX loaded GO-SB could be easily internalized by HepG2 cells and exhibit obvious cytotoxicity on the cells. And, in vivo studies demonstrate that the GO-SB drug carrier is capable of being taken by the larvae of zebrafish and can be eliminated from the body within several days.

Electrically-Transduced Chemical Sensors Based on Two-Dimensional Nanomaterials

Electrically-transduced sensors, with their simplicity and compatibility with standard electronic technologies, produce signals that can be efficiently acquired, processed, stored, and analyzed. Two dimensional (2D) nanomaterials, including graphene, phosphorene (BP), transition metal dichalcogenides (TMDCs), and others, have proven to be attractive for the fabrication of high-performance electrically-transduced chemical sensors due to their remarkable electronic and physical properties originating from their 2D structure. This review highlights the advances in electrically-transduced chemical sensing that rely on 2D materials. The structural components of such sensors are described, and the underlying operating principles for different types of architectures are discussed. The structural features, electronic properties, and surface chemistry of 2D nanostructures that dictate their sensing performance are reviewed. Key advances in the application of 2D materials, from both a historical and analytical perspective, are summarized for four different groups of analytes: gases, volatile compounds, ions, and biomolecules. The sensing performance is discussed in the context of the molecular design, structure-property relationships, and device fabrication technology. The outlook of challenges and opportunities for 2D nanomaterials for the future development of electrically-transduced sensors is also presented.

The assembly of silk fibroin and graphene-based nanomaterials with enhanced mechanical/conductive properties and their biomedical applications

The assembly of silk fibroin and graphene-based nanomaterials would present fantastic properties and functions via optimizing the interaction between each other, and can be processed into various formats to tailor specific biomedical applications.

Carbon-Based Nanomaterials for Cancer Therapy via Targeting Tumor Microenvironment

Cancer remains one of the major health problems all over the world and conventional therapeutic approaches have failed to attain an effective cure. Tumor microenvironments (TME) present a unique challenge in tumor therapy due to their complex structures and multiple components, which also serve as the soil for tumor growth, development, invasion, and migration. The complex TME includes immune cells, fibrous collagen structures, and tortuous blood vessels, in which conventional therapeutic approaches are rendered useless. State-of-the-art nanotechnologies have potential to cope with the threats of malignant tumors. With unique physiochemical properties, carbon nanomaterials (CNMs), including graphene, fullerenes, carbon nanotubes, and carbon quantum dots, offer opportunities to resolve the hurdles, by targeting not only cancer cells but also the TME. This review summarizes the progress about CNM-based cancer therapy strategies, which mainly focuses on both the treatment for cancer cells and TME-targeted modulation. In the last, the challenges for TME-based therapy via CNMs are discussed, which will be important in guiding current basic research to clinical translation in the future.

Interaction of Zwitterionic and Ionic Monomers with Graphene Surfaces

Measurement of the interaction force between two materials provides important information on various properties, such as adsorption, binding, or compatibility for coatings, adhesion, and composites. The interaction forces of zwitterionic and ionic monomers with graphite platelets (G) and reduced graphene oxide (rGO) surfaces were systematically investigated by atomic force microscopy (AFM) in air and water. The monomers examined were 2-(methacryloyloxy)ethyl 2-(trimethylammonio)ethyl phosphate (MPC), [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide (SBE), [2-(acryloyloxy)ethyl]trimethylammonium chloride (ATC), and 2-methyl-2-propene-1-sulfonic acid sodium (MSS). The AFM studies revealed that MSS and SBE monomers with sulfonate units have stronger interaction forces with G surface in air and that MPC and ATC monomers with quaternary ammonium units have higher interaction forces in water. In the case of rGO surface, the monomers with quaternary ammonium units showed stronger interactions regardless of the medium. These interactions could be rationalized by the interaction mechanism between the monomers with graphene surfaces, such as cation-π for MPC and ATC and anion-π for MSS and SBE. Overall, cation-π interactions were effective in water, whereas anion-π interactions are effective in air with G surface. The adhesion values of MPC, SBE, ATC, and MSS on rGO were lower than the values measured on G surface. Among the monomers, MPC showed the highest dispersibility for aqueous graphene dispersions. Further, the adsorption of MPC on G and rGO surfaces was verified by high-resolution transmission electron microscopy and X-ray diffraction patterns.

Theoretical study on the interactions between chlordecone hydrate and acidic surface groups of activated carbon under basic pH conditions

A theoretical study of the influence of acidic surface groups (SG) of activated carbon (AC) on chlordecone hydrate (CLDh) adsorption is presented, in order to help understanding the adsorption process under basic pH conditions. A seven rings aromatic system (coronene) with a functional group in the edge was used as a simplified model of AC to evaluate the influence of SG in the course of adsorption from aqueous solution at basic pH conditions. Two SG were modeled in their deprotonated form: carboxyl and hydroxyl (COO^- and O^-), interacting with CLDh. In order to model the solvation process, all systems under study were calculated with up to three water molecules. Multiple Minima Hypersurface (MMH) methodology was employed to study the interactions of CLDh with SG on AC using PM7 semiempirical Hamiltonian, to explore the potential energy surfaces of the systems and evaluate their thermodynamic association energies. The re-optimization of representative structures obtained from MMH was done using M06-2X Density Functional Theory. The Quantum Theory of Atoms in Molecules (QTAIM) was used to characterize the interaction types. As result, the association of CLDh with acidic SG at basic pH conditions preferentially occurs between the two alcohol groups of CLDh with COO^- and O^- groups and by dispersive interactions of chlorine atoms of CLDh with the graphitic surface. On the other hand, the presence of covalent interactions between the negatively charged oxygen of SG and one hydrogen atom of CLDh alcohol groups (O^-⋯HO interactions) without water molecules, was confirmed by QTAIM study. It can be concluded that the interactions of CLDh with acidic SG of AC under basic pH conditions confirms the physical mechanisms of adsorption process.

Highly Sensitive and Selective Potassium Ion Detection Based on Graphene Hall Effect Biosensors

Potassium (K⁺) ion is an important biological substance in the human body and plays a critical role in the maintenance of transmembrane potential and hormone secretion. Several detection techniques, including fluorescent, electrochemical, and electrical methods, have been extensively investigated to selectively recognize K⁺ ions. In this work, a highly sensitive and selective biosensor based on single-layer graphene has been developed for K⁺ ion detection under Van der Pauw measurement configuration. With pre-immobilization of guanine-rich DNA on the graphene surface, the graphene devices exhibit a very low limit of detection (≈1 nM) with a dynamic range of 1 nM–10 μM and excellent K⁺ ion specificity against other alkali cations, such as Na⁺ ions. The origin of K⁺ ion selectivity can be attributed to the fact that the formation of guanine-quadruplexes from guanine-rich DNA has a strong affinity for capturing K⁺ ions. The graphene-based biosensors with improved sensing performance for K⁺ ion recognition can be applied to health monitoring and early disease diagnosis.

Genipin-crosslinked adipose stem cell derived extracellular matrix-nano graphene oxide composite sponge for skin tissue engineering

3D Bioscaffold with relative high mechanical property was developed using rabbit ADSCs.

A new route for the synthesis of a Ag nanopore-inlay-nanogap structure: integrated Ag-core@graphene-shell@Ag-jacket nanoparticles for high-efficiency SERS detection

We present a new route for the synthesis of Ag nanopore-inlay-nanogap structures using creviced graphene-shell encapsulated Cu nanoparticles (Cu@G-NPs) as the sacrificial templates. The as-synthesized integrated Ag-core@graphene-shell@Ag-jacket nanoparticles (AgC@G@AgJ-NPs) presents "chrysanthemum" shapes that contain abundant sub-10 nm size intraparticle nanopores/nanogaps, which can generate huge enhanced electromagnetic fields to support SERS activity, resulting in an average EF > 10⁷ due to a high-density of intraparticle and interparticle "hot spots".

B–Hb⋯π interaction in borane–graphene complexes: coronene as a case study

N/B/BN doping in graphene enhances adsorption of boranes.

Enhancement of interaction of L-929 cells with functionalized graphene via COOH+ ion implantation vs. chemical method

Low hydrophilicity of graphene is one of the major obstacles for biomaterials application. To create some hydrophilic groups on graphene is addressed this issue. Herein, COOH+ ion implantation modified graphene (COOH+/graphene) and COOH functionalized graphene were designed by physical ion implantation and chemical methods, respectively. The structure and surface properties of COOH+/graphene and COOH functionalized graphene were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and contact angle measurement. Compared with graphene, COOH+/graphene and COOH functionalized graphene revealed improvement of cytocompatibility, including in vitro cell viability and morphology. More importantly, COOH+/graphene exhibited better improvement effects than functionalized graphene. For instance, COOH+/graphene with 1 × 1018 ions/cm2 showed the best cell-viability, proliferation and stretching. This study demonstrated that ion implantation can better improve the cytocompatibility of the graphene.

Feeding Single-Walled Carbon Nanotubes or Graphene to Silkworms for Reinforced Silk Fibers

Silkworm silk is gaining significant attention from both the textile industry and research society because of its outstanding mechanical properties and lustrous appearance. The possibility of creating tougher silks attracts particular research interest. Carbon nanotubes and graphene are widely studied for their use as reinforcement. In this work, we report mechanically enhanced silk directly collected by feeding Bombyx mori larval silkworms with single-walled carbon nanotubes (SWNTs) and graphene. We found that parts of the fed carbon nanomaterials were incorporated into the as-spun silk fibers, whereas the others went into the excrement of silkworms. Spectroscopy study indicated that nanocarbon additions hindered the conformation transition of silk fibroin from random coil and α-helix to β-sheet, which may contribute to increased elongation at break and toughness modules. We further investigated the pyrolysis of modified silk, and a highly developed graphitic structure with obviously enhanced electrical conductivity was obtained through the introduction of SWNTs and graphene. The successful generation of these SWNT- or graphene-embedded silks by in vivo feeding is expected to open up possibilities for the large-scale production of high-strength silk fibers.

Graphene oxide scaffold accelerates cellular proliferative response and alveolar bone healing of tooth extraction socket

Graphene oxide (GO) consisting of a carbon monolayer has been widely investigated for tissue engineering platforms because of its unique properties. For this study, we fabricated a GO-applied scaffold and assessed the cellular and tissue behaviors in the scaffold. A preclinical test was conducted to ascertain whether the GO scaffold promoted bone induction in dog tooth extraction sockets. For this study, GO scaffolds were prepared by coating the surface of a collagen sponge scaffold with 0.1 and 1 µg/mL GO dispersion. Scaffolds were characterized using scanning electron microscopy (SEM), physical testing, cell seeding, and rat subcutaneous implant testing. Then a GO scaffold was implanted into a dog tooth extraction socket. Histological observations were made at 2 weeks postsurgery. SEM observations show that GO attached to the surface of collagen scaffold struts. The GO scaffold exhibited an interconnected structure resembling that of control subjects. GO application improved the physical strength, enzyme resistance, and adsorption of calcium and proteins. Cytocompatibility tests showed that GO application significantly increased osteoblastic MC3T3-E1 cell proliferation. In addition, an assessment of rat subcutaneous tissue response revealed that implantation of 1 µg/mL GO scaffold stimulated cellular ingrowth behavior, suggesting that the GO scaffold exhibited good biocompatibility. The tissue ingrowth area and DNA contents of 1 µg/mL GO scaffold were, respectively, approximately 2.5-fold and 1.4-fold greater than those of the control. Particularly, the infiltration of ED2-positive (M2) macrophages and blood vessels were prominent in the GO scaffold. Dog bone-formation tests showed that 1 µg/mL GO scaffold implantation enhanced bone formation. New bone formation following GO scaffold implantation was enhanced fivefold compared to that in control subjects. These results suggest that GO was biocompatible and had high bone-formation capability for the scaffold. The GO scaffold is expected to be beneficial for bone tissue engineering therapy.

Theoretical study of adsorption of amino acids on graphene and BN sheet in gas and aqueous phase with empirical DFT dispersion correction

Suitability of BN nanosheet/graphene towards the adsorption of amino acids established by dispersion corrected DFT calculations.

Novel insights into l-cysteine adsorption on transition metal doped graphene: influences of the dopant and the vacancy

Unprotonated l-cysteine is docked on single-vacancy and double-vacancy graphenes doped with transition metals from Sc to Zn. The adsystems exhibit interesting adsorption stability and magnetism.

Modelling of graphene functionalization

This perspective describes the available theoretical methods and models for simulating graphene functionalization based on quantum and classical mechanics.

Activity of Fe2O3 with a high index facet for bituminous coal chemical looping combustion: a theoretical and experimental study

Iron-based oxide with high miller index facet Fe₂O₃(104) effectively promotes oxygen transfer at different oxidation states for oxidizing coal molecules into CO₂ and H₂O during chemical looping combustion of solid fuel.