Graphene nanoribbon: An emerging and efficient flat molecular platform for advanced biosensing

Graphene oxide nanoribbons conjugated with 1, 2-distearoyl-sn-glycero-3 phosphoethanolamine-poly (ethylene glycol)-transferrin enhanced targeted delivery and cytotoxicity of raloxifene against breast cancer

The clinical utility of raloxifene (RLX), a selective estrogen receptor modulator (SERM), has been compromised by severe side effects and unfavorable drug properties. To address these, a transferrin (Tf) conjugated graphene oxide nanoribbon (GONR) platform was tried for RLX. The stability of GONRs in biological media was improved by surface modification with 1, 2-Distearoyl-sn-glycero-3 phosphoethanolamine-Poly (ethylene glycol) (DSPE-PEG). The Tf molecule was covalently attached to DSPE-PEG (DPT) using EDC-NHS chemistry. The surface of GONR was then modified with DSPE-PEG (DP) or DPT and loaded with RLX (GDP-RLX and GDPT-RLX). The final formulations were characterized for drug loading and stability. The anticancer activities of pure RLX, GDP-RLX, and GDPT-RLX were evaluated and compared in all the in vitro and in vivo studies. In vitro cell line studies showed that GDPT-RLX have significantly high cytotoxicity, cellular uptake, apoptosis induction, G2/M phase arrest, anti-migration properties, and apoptotic protein expression, followed by GDP-RLX and RLX. Pharmacokinetics and tumor biodistribution were also found to be excellent with GDPT-RLX. The in vivo tumor therapy and tumor evaluation outcomes were also consistent with the in vitro data. The Tf conjugated GDPT-RLX represents a promising approach for targeted and sustained delivery of RLX with enhanced therapeutic efficacy.

Advances on carbon nanomaterials and their applications in medical diagnosis and drug delivery

Carbon nanomaterials are indispensable due to their unique properties of high electrical conductivity, mechanical strength and thermal stability, which makes them important nanomaterials in biomedical applications and waste management. Limitations of conventional nanomaterials, such as limited surface area, difficulty in fine tuning electrical or thermal properties and poor dispersibility, calls for the development of advanced nanomaterials to overcome such limitations. Commonly, carbon nanomaterials were synthesized by chemical vapor deposition (CVD), laser ablation or arc discharge methods. The advancement in these techniques yielded monodispersed carbon nanotubes (CNTs) and allows p-type and n-type doping to enhance its electrical and catalytic activities. The functionalized CNTs showed exceptional mechanical, electrical and thermal conductivity (3500-5000 W/mK) properties. On the other hand, carbon quantum dots (CQDs) exhibit strong photoluminescence properties with high quantum yield. Carbon nanohorns are another fascinating type of nanomaterial that exhibit a unique structure with high surface area and excellent adsorption properties. These carbon nanomaterials could improve waste management by adsorbing pollutants from water and soil, enabling precise environmental monitoring, while enhancing wastewater treatment and drug delivery systems. Herein, we have discussed the potentials of all these carbon nanomaterials in the context of innovative waste management solutions, fostering cleaner environments and healthier ecosystems for diverse biomedical applications such as biosensing, drug delivery, and environmental monitoring.

Nanomaterials revolutionize biosensing: 0D-3D designs for ultrasensitive detection of microorganisms and viruses

Various diseases caused by harmful microorganisms and viruses have caused serious harm and huge economic losses to society. Thus, rapid detection of harmful microorganisms and viruses is necessary for disease prevention and treatment. Nanomaterials have unique properties that other materials do not possess, such as a small size effect and quantum size effect. Introducing nanomaterials into biosensors improves the performance of biosensors for faster and more accurate detection of microorganisms and viruses. This review aims to introduce the different kinds of biosensors and the latest advances in the application of nanomaterials in biosensors. In particular, this review focuses on describing the physicochemical properties of zero-, one-, two-, and three-dimensional nanostructures as well as nanoenzymes. Finally, this review discusses the applications of nanobiosensors in the detection of microorganisms and viruses and the future directions of nanobiosensors.

Graphene-Based Photodynamic Therapy and Overcoming Cancer Resistance Mechanisms: A Comprehensive Review

Photodynamic therapy (PDT) is a non-invasive therapy that has made significant progress in treating different diseases, including cancer, by utilizing new nanotechnology products such as graphene and its derivatives. Graphene-based materials have large surface area and photothermal effects thereby making them suitable candidates for PDT or photo-active drug carriers. The remarkable photophysical properties of graphene derivates facilitate the efficient generation of reactive oxygen species (ROS) upon light irradiation, which destroys cancer cells. Surface functionalization of graphene and its materials can also enhance their biocompatibility and anticancer activity. The paper delves into the distinct roles played by graphene-based materials in PDT such as photosensitizers (PS) and drug carriers while at the same time considers how these materials could be used to circumvent cancer resistance. This will provide readers with an extensive discussion of various pathways contributing to PDT inefficiency. Consequently, this comprehensive review underscores the vital roles that graphene and its derivatives may play in emerging PDT strategies for cancer treatment and other medical purposes. With a better comprehension of the current state of research and the existing challenges, the integration of graphene-based materials in PDT holds great promise for developing targeted, effective, and personalized cancer treatments.

Nickel-Induced Reduced Graphene Oxide Nanoribbon Formation on Highly Ordered Pyrolytic Graphite for Electronic and Magnetic Applications

The development of nanoribbon-like structures is an effective strategy to harness the potential benefits of graphenic materials due to their excellent electrical properties, advantageous edge sites, rapid electron transport, and large specific area. Herein, parallel and connected magnetic nanostructured nanoribbons are obtained through the synthesis of reduced graphene oxide (rGO) using NiCl2 as a precursor with potential applications in nascent electronic and magnetic devices. Several analytical techniques have been used for the thorough characterization of the modified surfaces. Atomic force microscopy (AFM) shows the characteristic topographical features of the nanoribbons. While X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and Raman spectroscopy provided information on the chemical state of Ni and graphene-like structures, magnetic force microscopy (MFM) and scanning Kelvin probe microscopy (SKPFM) confirmed the preferential concentration of Ni onto rGO nanoribbons. These results indicate that the synthesized material shows 1D ordering of nickel nanoparticles (NiNPs)-decorating tiny rGO flakes into thin threads and the subsequent 2D arrangement of the latter into parallel ribbons following the topography of the HOPG basal plane.

Width effects on bilayer graphene nanoribbon polarons

Recent progress in nanoelectronics suggests that stacking armchair graphene nanoribbons (AGNRs) into bilayer systems can generate materials with emergent quasiparticle properties. In this context, the impact of width changes is especially relevant. However, its effect on charged carriers remains elusive. In this work, we investigate the effect of width and interlayer interaction changes on polaron states via a hybrid Hamiltonian that couples the electronic and lattice interactions. Results show the rising of two interlayer polarons: the non-symmetric and the symmetric. The coupling strength needed to induce the transition between states depends on the nanoribbon width, being at the most extreme case of ≈174 meV. Electronic properties such as the coupling strength threshold, carrier size, and gap are shown to respect the AGNR width family 3p, 3p + 1, and 3p + 2 rule. The findings demonstrate that strong interlayer interaction simultaneously delocalizes the carriers and reduces the gap up to 0.6 eV. Additionally, it is found that some layers are more prone to share charge, indicating a potential heterogeneous stacking where a particular electronic pathway is favored. The results present an encouraging prospect for integrating AGNR bilayers in future flexible electronics.

"Clickable" graphene nanoribbons for biosensor interfaces

We report on the synthesis of "clickable" graphene nanoribbons (GNRs) and their application as a versatile interface for electrochemical biosensors. GNRs are successfully deposited on gold-coated working electrodes and serve as a platform for the covalent anchoring of a bioreceptor (i.e., a DNA aptamer), enabling selective and sensitive detection of Interleukin 6 (IL6). Moreover, when applied as the intermediate linker on reduced graphene oxide (rGO)-based field-effect transistors (FETs), the GNRs provide improved robustness compared to conventional aromatic bi-functional linker molecules. GNRs enable an orthogonal and covalent attachment of a recognition unit with a considerably higher probe density than previously established methods. Interestingly, we demonstrate that GNRs introduce photoluminescence (PL) when applied to rGO-based FETs, paving the way toward the simultaneous optical and electronic probing of the attached biointerface.

Hybrid Edge Results in Narrowed Band Gap: Bottom-up Liquid-Phase Synthesis of Bent N = 6/8 Armchair Graphene Nanoribbons

Scalable fabrication of graphene nanoribbons with narrow band gaps has been a nontrivial challenge. Here, we have developed a simple approach to access narrow band gaps using hybrid edge structures. Bottom-up liquid-phase synthesis of bent N = 6/8 armchair graphene nanoribbons (AGNRs) has been achieved in high efficiency through copolymerization between an o-terphenyl monomer and a naphthalene-based monomer, followed by Scholl oxidation. An unexpected 1,2-aryl migration has been discovered, which is responsible for introducing kinked structures into the GNR backbones. The N = 6/8 AGNRs have been fully characterized to support the proposed structure and show a narrow band gap and a relatively high electrical conductivity. In addition, their application in efficient gas sensing has also been demonstrated.

Carbon-Based Electrochemical (Bio)sensors for the Detection of Carbendazim: A Review

Carbendazim, a fungicide widely used in agriculture, has been classified as a hazardous chemical by the World Health Organization due to its environmental persistence. It is prohibited in several countries; therefore, detecting it in food and environmental samples is highly necessary. A reliable, rapid, and low-cost method uses electrochemical sensors and biosensors, especially those modified with carbon-based materials with good analytical performance. In this review, we summarize the use of carbon-based electrochemical (bio)sensors for detecting carbendazim in environmental and food matrixes, with a particular interest in the role of carbon materials. Focus on publications between 2018 and 2023 that have been describing the use of carbon nanotubes, carbon nitride, graphene, and its derivatives, and carbon-based materials as modifiers, emphasizing the analytical performance obtained, such as linear range, detection limit, selectivity, and the matrix where the detection was applied.

Photoinduced edge-specific nanoparticle decoration of two-dimensional tungsten diselenide nanoribbons

Metallic nanoparticles are widely explored for boosting light-matter coupling, optoelectronic response, and improving photocatalytic performance of two-dimensional (2D) materials. However, the target area is restricted to either top or bottom of the 2D flakes. Here, we introduce an approach for edge-specific nanoparticle decoration via light-assisted reduction of silver ions and merging of silver seeds. We observe arrays of the self-limited in size silver nanoparticles along tungsten diselenide WSe2 nanoribbon edges. The density of nanoparticles is tunable by adjusting the laser fluence. Scanning electron microscopy, atomic force microscopy, and Raman spectroscopy are used to investigate the size, distribution, and photo-response of the deposited plasmonic nanoparticles on the quasi-one-dimensional nanoribbons. We report an on-surface synthesis path for creating mixed-dimensional heterostructures and heterojunctions with potential applications in opto-electronics, plasmonics, and catalysis, offering improved light matter coupling, optoelectronics response, and photocatalytic performance of 2D materials.

Carbon-based biosensors from graphene family to carbon dots: A viewpoint in cancer detection

According to the latest report by International Agency for Research on Cancer, 19.3 million new cancer cases and 10 million cancer deaths were globally reported in 2020. Early diagnosis can reduce these numbers significantly, and biosensors have appeared to be a solution to this problem as, unlike the traditional methods, they have low cost, rapid process, and do not need experts present on site for use. These devices have been incorporated to detect many cancer biomarkers and measure cancer drug delivery. To design these biosensors, a researcher must know about their different types, properties of nanomaterials, and cancer biomarkers. Among all types of biosensors, electrochemical and optical biosensors are the most sensitive and promising sensors for detecting complicated diseases like cancer. The carbon-based nanomaterial family has attracted lots of attention due to their low cost, easy preparation, biocompatibility, and significant electrochemical and optical properties. In this review, we have discussed the application of graphene and its derivatives, carbon nanotubes (CNTs), carbon dots (CDs), and fullerene (C60), for designing different electrochemical and optical cancer-detecting biosensors. Furthermore, the application of these carbon-based biosensors for detecting seven widely studied cancer biomarkers (HER2, CEA, CA125, VEGF, PSA, Alpha-fetoprotein, and miRNA21) is reviewed. Finally, various fabricated carbon-based biosensors for detecting cancer biomarkers and anticancer drugs are comprehensively summarized as well.

Electronic, transport, magnetic and optical properties of graphene nanoribbons review

Low dimensional materials have attracted great research interest from both theoretical and experimental point of view. These materials exhibit novel physical and chemical properties due to the confinement effect in low dimensions. The experimental observations of graphene open a new platform to study the physical properties of materials restricted to two dimensions. This featured article provides a review on the novel properties of quasi one-dimensional (1D) material known as graphene nanoribbon. Graphene nanoribbons can be obtained by unzipping carbon nanotubes (CNTs) or cutting the graphene sheet. Alternatively, it is also called the finite termination of graphene edges. It gives rise different edge geometries namely zigzag and armchair among others. There are various physical and chemical techniques to realize these materials. Depending on the edge type termination, these are called the zigzag and armchair graphene nanoribbons (ZGNR and AGNR). These edges play an important role in controlling the properties of graphene nanoribbons. The present review article provides an overview of the electronic, transport, optical and magnetic properties of graphene nanoribbons. However, there are different ways to tune these properties for device applications. Here, some of them are highlighted such as external perturbations and chemical modifications. Few applications of graphene nanoribbon have and chemical modifications. Few applications of graphene nanoribbon have also been briefly discussed.

Role of Förster Resonance Energy Transfer in Graphene-Based Nanomaterials for Sensing

Förster resonance energy transfer (FRET)-based fluorescence sensing of various target analytes has been of growing interest in the environmental, bioimaging, and diagnosis fields. Graphene-based zero- (0D) to two-dimensional (2D) nanomaterials, such as graphene quantum dots (GQDs), graphene oxide (GO), reduced graphene oxide (rGO), and graphdiyne (GD), can potentially be employed as donors/acceptors in FRET-based sensing approaches because of their unique electronic and photoluminescent properties. In this review, we discuss the basics of FRET, as well as the role of graphene-based nanomaterials (GQDs, GO, rGO, and GD) for sensing various analytes, including cations, amino acids, explosives, pesticides, biomolecules, bacteria, and viruses. In addition, the graphene-based nanomaterial sensing strategy could be applied in environmental sample analyses, and the reason for the lower detection ranges (micro- to pico-molar concentration) could also be explained in detail. Challenges and future directions for designing nanomaterials with a new sensing approach and better sensing performance will also be highlighted.

Transport properties of MoS2/V7(Bz)8 and graphene/V7(Bz)8 vdW junctions tuned by bias and gate voltages

The MoS2/V7(Bz)8 and graphene/V7(Bz)8 vdW junctions are designed and the transport properties of their four-terminal devices are comparatively investigated based on density functional theory (DFT) and the nonequilibrium Green's function (NEGF) technique. The MoS2 and graphene nanoribbons act as the source-to-drain channel and the spin-polarized one-dimensional (1D) benzene-V multidecker complex nanowire (V7(Bz)8) serves as the gate channel. Gate voltages applied on V7(Bz)8 exert different influences of electron transport on MoS2/V7(Bz)8 and graphene/V7(Bz)8. In MoS2/V7(Bz)8, the interplay of source and gate bias potentials could induce promising properties such as negative differential resistance (NDR) behavior, output/input current switching, and spin-polarized currents. In contrast, the gate bias plays an insignificant effect on the transport along graphene in graphene/V7(Bz)8. This dissimilarity is attributed to the fact that the conductivity follows the sequence of MoS2 < V7(Bz)8 < graphene. These transport characteristics are examined by analyzing the conductivity, the currents, the local density of states (LDOS), and the transmission spectra. These results are valuable in designing multi-terminal nanoelectronic devices.

Coupled Multiphysics Modelling of Sensors for Chemical, Biomedical, and Environmental Applications with Focus on Smart Materials and Low-Dimensional Nanostructures

Low-dimensional nanostructures have many advantages when used in sensors compared to the traditional bulk materials, in particular in their sensitivity and specificity. In such nanostructures, the motion of carriers can be confined from one, two, or all three spatial dimensions, leading to their unique properties. New advancements in nanosensors, based on low-dimensional nanostructures, permit their functioning at scales comparable with biological processes and natural systems, allowing their efficient functionalization with chemical and biological molecules. In this article, we provide details of such sensors, focusing on their several important classes, as well as the issues of their designs based on mathematical and computational models covering a range of scales. Such multiscale models require state-of-the-art techniques for their solutions, and we provide an overview of the associated numerical methodologies and approaches in this context. We emphasize the importance of accounting for coupling between different physical fields such as thermal, electromechanical, and magnetic, as well as of additional nonlinear and nonlocal effects which can be salient features of new applications and sensor designs. Our special attention is given to nanowires and nanotubes which are well suited for nanosensor designs and applications, being able to carry a double functionality, as transducers and the media to transmit the signal. One of the key properties of these nanostructures is an enhancement in sensitivity resulting from their high surface-to-volume ratio, which leads to their geometry-dependant properties. This dependency requires careful consideration at the modelling stage, and we provide further details on this issue. Another important class of sensors analyzed here is pertinent to sensor and actuator technologies based on smart materials. The modelling of such materials in their dynamics-enabled applications represents a significant challenge as we have to deal with strongly nonlinear coupled problems, accounting for dynamic interactions between different physical fields and microstructure evolution. Among other classes, important in novel sensor applications, we have given our special attention to heterostructures and nucleic acid based nanostructures. In terms of the application areas, we have focused on chemical and biomedical fields, as well as on green energy and environmentally-friendly technologies where the efficient designs and opportune deployments of sensors are both urgent and compelling.

Photoluminescent Semiconducting Graphene Nanoribbons via Longitudinally Unzipping Single-Walled Carbon Nanotubes

The lack of a sizeable band gap has so far prevented graphene from building effective electronic and optoelectronic devices despite its numerous exceptional properties. Intensive theoretical research reveals that a band gap larger than 1 eV can only be achieved in sub-3 nm wide graphene nanoribbons (GNRs), but real fabrication of such ultranarrow GNRs still remains a critical challenge. Herein, we demonstrate an approach for the synthesis of ultranarrow and photoluminescent semiconducting GNRs by longitudinally unzipping single-walled carbon nanotubes. Atomic force microscopy reveals the unzipping process, and the resulting 2.2 nm wide GNRs are found to emit strong and sharp photoluminescence at ∼685 nm, demonstrating a very desirable semiconducting nature. This band gap of 1.8 eV is further confirmed by follow-up photoconductivity measurements, where a considerable photocurrent is generated, as the excitation wavelength becomes shorter than 700 nm. More importantly, our fabricated GNR field-effect transistors (FETs), by employing the hexagonal boron nitride-encapsulated heterostructure to achieve edge-bonded contacts, demonstrate a high current on/off ratio beyond 105 and carrier mobility of 840 cm2/V s, approaching the theoretical scattering limit in semiconducting GNRs at room temperature. Especially, highly aligned GNR bundles with lengths up to a millimeter are also achieved by prepatterning a template, and the fabricated GNR bundle FETs show a high on/off ratio reaching 105, well-defined saturation currents, and strong light-emitting properties. Therefore, GNRs produced by this method open a door for promising applications in graphene-based electronics and optoelectronics.

Graphene Nanoribbons: Prospects of Application in Biomedicine and Toxicity

Graphene nanoribbons are a type of graphene characterized by remarkable electrical and mechanical properties. This review considers the prospects for the application of graphene ribbons in biomedicine, taking into account safety aspects. According to the analysis of the recent studies, the topical areas of using graphene nanoribbons include mechanical, chemical, photo- and acoustic sensors, devices for the direct sequencing of biological macromolecules, including DNA, gene and drug delivery vehicles, and tissue engineering. There is evidence of good biocompatibility of graphene nanoribbons with human cell lines, but a number of researchers have revealed toxic effects, including cytotoxicity and genotoxicity. Moreover, the damaging effects of nanoribbons are often higher than those of chemical analogs, for instance, graphene oxide nanoplates. The possible mechanism of toxicity is the ability of graphene nanoribbons to damage the cell membrane mechanically, stimulate reactive oxidative stress (ROS) production, autophagy, and inhibition of proliferation, as well as apoptosis induction, DNA fragmentation, and the formation of chromosomal aberrations. At the same time, the biodegradability of graphene nanoribbons under the environmental factors has been proven. In general, this review allows us to conclude that graphene nanoribbons, as components of high-precision nanodevices and therapeutic agents, have significant potential for biomedical applications; however, additional studies of their safety are needed. Particular emphasis should be placed on the lack of information about the effect of graphene nanoribbons on the organism as a whole obtained from in vivo experiments, as well as about their ecological toxicity, accumulation, migration, and destruction within ecosystems.

Graphene Nanoribbon Grids of Sub-10 nm Widths with High Electrical Connectivity

Quasi-one-dimensional (1D) graphene nanoribbons (GNRs) have finite band gaps and active edge states and therefore can be useful for advanced chemical and electronic devices. Here, we present the formation of GNR grids via seed-assisted chemical vapor deposition on Ge(100) substrates. Nucleation seeds, provided by unzipped C₆₀, initiated growth of the GNRs. The GNRs grew toward two orthogonal directions in an anisotropic manner, templated by the single crystalline substrate, thereby forming grids that had lateral stitching over centimeter scales. The spatially uniform grid can be transferred and patterned for batch fabrication of devices. The GNR grids showed percolative conduction with a high electrical sheet conductance of ∼2 μS·sq and field-effect mobility of ∼5 cm²/(V·s) in the macroscopic channels, which confirm excellent lateral stitching between domains. From transconductance measurements, the intrinsic band gap of GNRs with sub-10 nm widths was estimated as ∼80 meV, similar to theoretical expectation. Our method presents a scalable way to fabricate atomically thin elements with 1D characteristics for integration with various nanodevices.