Covalently linked, water-dispersible, cyclodextrin: reduced-graphene oxide sheets

β-cyclodextrin modified GO ultrafiltration membranes with enhanced antifouling property for water purification

The study investigated the influence of additives on the fabrication of mixed matrix membranes comprising polyethersulfone (PES), with a specific focus on hydrophilicity, flux, morphology, and antifouling properties. Carboxymethyl modified β-cyclodextrin (CMβ-CD) was used to enhance the dispersion and hydrophilicity of graphene oxide (GO), leading to the formation of a hydrophilic and stable composite nanoparticle (CMCD@GO). The hydrophilicity (WCA <51.5°) and water flux (32.6 L.m-2.h-1) of the modified PES membranes (MCDGO-x) were improved by the incorporation of CMCD@GO nanoparticles, while that of PES membrane was 79.7° and 10.6 L.m-2.h-1. The rate of backscattered light intensity (ΔBS) of MCDGO-x suspensions remains stable, suggesting stable dispersion of CMCD@GO in organic solvents. Compared to the bare PES membrane, the MCDGO-x membrane exhibits a thinner active layer and a finger-like structure. The MCDGO-x membrane exhibited excellent naphthenic acids (NAs) rejection (> 93.2%) due to reduced roughness and higher hydrophilicity, while the GO-modified PES membrane (MGO-5) exhibited lower NAs rejection (87.2%). Furthermore, the MCDGO-5 membrane showed higher flux recovery ratio (FRR) of 79.3% compared to MGO-5 membrane (68.5%) after three cycles, indicating the antifouling performance of MCDGO-x for NAs was significantly improved. The combination of CMβ-CD and GO enhance the flux and antifouling properties of PES ultrafiltration membranes, suggesting significant potential for applications in the purification of oil sands process water and the treatment of oily wastewater.

Applicability of a graphene oxide nanocomposite for fabrication of an electrochemical sensor for simultaneous detection of sunset yellow and rhodamine B in food samples

Developing a sensitive portable sensor for the determination of food additives is very important. Herein, a simple and sensitive electrochemical sensor has been constructed based on a carbon paste electrode (CPE) modified with graphene oxide (GO) nanosheets for the simultaneous determination of sunset yellow (SY) and rhodamine B (RhB) in phosphate buffer solution (pH = 4). The cyclic and differential pulse voltammetry (CV and DPV) results revealed two well-resolved anodic peaks for SY and RhB with a remarkable increase in oxidation signals of these colorants. Based on this, an electrochemical method was developed for the first time for the simultaneous detection of SY and RhB. Applicability of the sensor was confirmed in various concentrations of two analytes in two linear ranges of 1-20 μM for SY and 1-30 μM for RhB with a limit of detection (LOD) of 10.0 nM and 20.0 nM, respectively. Furthermore, the proposed sensor was successfully employed for the simultaneous detection of SY and RhB in food samples with recoveries of 93.1-106.0% indicating promising potential in practical application.

Corrosion self-warning and repair tracking of polymeric coatings based on stimulus responsive nanosensors

Smart polymeric coatings with early corrosion self-warning and damage self-repairing characteristics have garnered tremendous interest due to their ability to sense corrosion reactions and repair coating defects. However, tracking the repair process and its underlying protection mechanism is highly challenging. Herein, we report the construction of a novel composite coating by incorporating multifunctional nanosensors (graphene oxide-zeolitic imidazole frameworks loaded with 1,10-phenanthroline) into a thermo-responsive polyurethane. Under damaging events, the localized acidity derived from metal corrosion stimulates the decomposition of the nanosensors to produce 1,10-phenanthroline and benzimidazole. The generated ferrous ions are rapidly sensed by the released 1,10-phenanthroline to produce a conspicuous red color, which warns of the corrosion occurrence. In profiting from the photothermal effect of graphene oxide, the composite coating exhibits efficient crack closure behavior under near-infrared light irradiation. Morphology observation indicates that a coating scratch (about 30 μm wide) almost closed with 20 s of irradiation. The photothermally activated crack closure combined with benzimidazole inhibition endows the prepared coating with superior self-repairing performance. Interestingly, the change in color intensity around the coating defect can assist in tracking the repair process. Therefore, this work provides a novel strategy to visualize microscopic behaviors during damage and repair processes.

Carbon-based aerogels for biomedical sensing: Advances toward designing the ideal sensor

Carbon based aerogels are special solid-state materials comprised of interconnected networks of 3D nanostructures with high amount of air-filled nanoporous. They expand the structural properties along with physicochemical characteristics of nanoscale construction blocks to macroscale, and incorporate distinctive attributes of aerogels, like large surface area, high porosity, and low density, with particular features of the different constituents. These features impart aerogels with rapid response signal, high selectivity, and ultra-sensitivity for sensing diverse targets in biomedical media. This has prompted researchers to develop a variety of aerogel-based sensors with encouraging achievements. Hence, this work outlines sensing applications of aerogel-based sensors with a comprehensive overview on the carbon aerogel hybrid materials and their analytical performances. Authors tried to list advantages and limitations of the developed approach and introduced more potent research for possible devices designing. We also point out some challenges and future perspectives related to the improvement of high-efficiency aerogel-based sensors.

Bio-inspired graphene-based nano-systems for biomedical applications

The increasing demands of environmentally sustainable, affordable, and scalable materials have inspired researchers to explore greener nanosystems of unique properties which can enhance the performance of existing systems. Such nanosystems, extracted from nature, are state-of-art high-performance nanostructures due to intrinsic hierarchical micro/nanoscale architecture and generous interfacial interactions in natural resources. Among several, bio-inspired nanosystems graphene nanosystems have emerged as an essential nano-platform wherein a highly electroactive, scalable, functional, flexible, and adaptable to a living being is a key factor. Preliminary investigation project bio-inspired graphene nanosystems as a multi-functional nano-platform suitable for electronic devices, energy storage, sensors, and medical sciences application. However, a broad understanding of bio-inspired graphene nanosystems and their projection towards applied application is not well-explored yet. Considering this as a motivation, this mini-review highlights the following; the emergence of bio-inspired graphene nanosystems, over time development to make them more efficient, state-of-art technology, and potential applications, mainly biomedical including biosensors, drug delivery, imaging, and biomedical systems. The outcomes of this review will certainly serve as a guideline to motivate scholars to design and develop novel bio-inspired graphene nanosystems to develop greener, affordable, and scalable next-generation biomedical systems.

Selective capturing and fluorescence “turn on” detection of dibutyl phthalate using a molecular imprinted nanocomposite

Fluorescence-based selective detection of dibutyl phthalate is achieved via a paper-strip-based approach.

First example of engineered β-cyclodextrinylated MEMS devices for volatile pheromone sensing of olive fruit pests

Olive oil is more preferred than other vegetable oils because of the increasing health concern among people throughout the world. The major hindrance in large-scale production of olive oil is olive fruit pests which cause serious economic damage to the olive orchards. This requires careful monitoring and timely application of suitable remedies before pest infestation. Herein we demonstrate efficacious utilization of covalently functionalized β-cyclodextrinylated MEMS devices for selective and sensitive detection of female sex pheromone of olive fruit pest, Bactocera oleae. Two of the MEMS devices, silicon dioxide surface-micromachined cantilever arrays and zinc oxide surface-microfabricated interdigitated circuits, have been used to selectively capture the major pheromone component, 1,7-dioxaspiro[5,5]undecane. The non-covalent capture of olive pheromones inside the β-cyclodextrin cavity leads to the reduction of resonant frequency of the cantilevers, whereas an increase in resistance has been found in case of zinc oxide derived MEMS devices. Sensitivity of the MEMS devices towards the olive pheromone was found to be directly correlated with the increasing availability of β-cyclodextrin moieties over the surface of the devices and thus the detection limit of the devices has been achieved to a value as low as 0.297 ppq of the olive pheromone when the devices were functionalized with one of the standardized protocols. Overall, the reversible usability and potential capability of the suitably functionalized MEMS devices to selectively detect the presence of female sex pheromone of olive fruit fly before the onset of pest infestation in an orchard makes the technology quite attractive for viable commercial application.

Role of surface oxygen-containing functional groups of graphene oxide quantum dots on amyloid fibrillation of two model proteins

There are many reports demonstrating that various derivatives of carbon nanoparticles are effective inhibitors of protein aggregation. As surface structural features of nanoparticles play a key role on modulating amyloid fibrillation process, in the present in vitro study, bovine insulin and hen egg white lysozyme (HEWL) were selected as two model proteins to investigate the reducing effect of graphene oxide quantum dots (GOQDs) on their assembly under amyloidogenic conditions. GOQDs were prepared through direct pyrolysis of citric acid, and the reduction step was carried out using ascorbic acid. The prepared nanoparticles were characterized by UV-Vis, X-ray photoelectron, and FT-IR spectroscopies, transmission electron and atomic force microscopies, zeta potential measurement, and Nile red fluorescence assay. They showed the tendencies to modulate the assembly of the proteins through different mechanisms. While GOQDs appeared to have the capacity to inhibit fibrillation, the presence of reduced GOQDs (rGOQDs) was found to promote protein assembly via shortening the nucleation phase, as suggested by ThT fluorescence data. Moreover, the structures produced in the presence of GOQDs or rGOQDs were totally nontoxic. We suggest that surface properties of these particles may be part of the differences in their mechanism(s) of action.

Cucurbit[8]uril-Derived Graphene Hydrogels

The scalable production of uniformly distributed graphene (GR)-based composite materials remains a sizable challenge. While GR-polymer nanocomposites can be manufactured at a large scale, processing limitations result in poor control over the homogeneity of hydrophobic GR sheets in the matrices. Such processes often result in difficulties controlling stability and avoiding aggregation, therefore eliminating benefits that might have otherwise arisen from the nanoscopic dimensions of GR. Here, we report an exfoliated and stabilized GR dispersion in water. Cucurbit[8]uril (CB[8])-mediated host-guest chemistry was used to obtain supramolecular hydrogels consisting of uniformly distributed GR and guest-functionalized macromolecules. The obtained GR hydrogels show superior bioelectrical properties over identical systems produced without CB[8]. Utilizing such supramolecular interactions with biologically derived macromolecules is a promising approach to stabilize graphene in water and avoid oxidative chemistry.

Chemical Tuning of Specific Capacitance in Functionalized Fluorographene

Owing to its high surface area and excellent conductivity, graphene is considered an efficient electrode material for supercapacitors. However, its restacking in electrolytes hampers its broader utilization in this field. Covalent graphene functionalization is a promising strategy for providing more efficient electrode materials. The chemistry of fluorographene is particularly attractive as it allows scalable chemical production of useful graphene derivatives. Nevertheless, the influence of chemical composition on the capacitance of graphene derivatives is a largely unexplored field in nanomaterials science, limiting further development of efficient graphene-based electrode materials. In the present study, we obtained well-defined graphene derivatives differing in chemical composition but with similar morphologies by controlling the reaction time of 5-aminoisophthalic acid with fluorographene. The gravimetric specific capacitance ranged from 271 to 391 F g-1 (in 1 M Na2SO4), with the maximum value achieved by a delicate balance between the amount of covalently grafted functional groups and density of the sp2 carbon network governing the conductivity of the material. Molecular dynamics simulations showed that covalent grafting of functional groups with charged and ionophilic/hydrophilic character significantly enhanced the ionic concentration and hydration due to favorable electrostatic interactions among the charged centers and ions/water molecules. Therefore, conductive and hydrophilic graphitic surfaces are important features of graphene-based supercapacitor electrode materials. These findings provide important insights into the role of chemical composition on capacitance and pave the way toward designing more efficient graphene-based supercapacitor electrode materials.

Synthesis of nanocomposites using xylan and graphite oxide for remediation of cationic dyes in aqueous solutions

Due to the rapid development of industrialization, the water resources on which we depend are facing unprecedented challenges. Dyes, as an indispensable substance in our lives, have caused great pollution to the water resources in nature, and the removal of dyes from wastewater is becoming an important topic. A porous xylan/poly(acrylic acid)/graphite oxide nanocomposite was prepared by graft polymerization and used for adsorption of cationic ethyl violet dye in wastewaters in this paper. Various techniques, i.e., Fourier-transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, elemental analysis, scanning electron microscopy, and ultraviolet-visible spectroscopy, were used to study this composite. Adsorption isotherm measurements showed that the composite's adsorption behavior fits the Langmuir isotherm adsorption model. Adsorption tests showed that this material has excellent adsorption properties; the maximum adsorption capacity for ethyl violet dye was 273.99 mg/g. Investigation of the adsorption mechanism indicated that electrostatic forces and π-π effects are mainly involved in adsorption. Desorption cycling tests showed that the adsorption efficiency of the composite was still over 95% after 3 cycles. These results show that this porous xylan/poly (acrylic acid)/graphite oxide nanocomposite has potential applications in cationic dye removal.

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.

Recent advances in colloidal nanocomposite designviaheterogeneous polymerization techniques

Recent advances in colloidal nanocomposite design by heterogeneous polymerization are reviewed, with a specific focus on encapsulation and particle-based stabilization for specific materials applications.

A facile route to mechanically robust graphene oxide fibers

Excellent mechanical, electrical, and thermal properties of graphene have been achieved at the macroscale by assembling individual graphene or graphene oxide (GO) particles. Wet-spinning is an efficient and well-established process that can provide GO assemblies in fiber form. The coagulation bath in the wet-spinning process has rarely been considered for the design of mechanically robust GO fibers (GOFs). In this study, locating the amidation reaction in the coagulation bath yielded mechanically improved GOFs. The imides 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide were used to form covalent amide bonds between GO flakes and chitosan, thereby reinforcing the GOFs. Evidence and effects of the amidation reaction were systematically examined. The tensile strength and breaking strain of the GOFs improved by 41.6% and 75.2%, respectively, and the toughness almost doubled because of the optimized crosslinking reaction. Our work demonstrated that using a coagulation bath is a facile way to enhance the mechanical properties of GOFs.

Excellent mechanical, electrical, and thermal properties of graphene have been achieved at the macroscale by assembling individual graphene or graphene oxide (GO) particles.

Robust Covalent Coupling Scheme for the Development of FRET Aptasensor based on Amino-Silane-Modified Graphene Oxide

In recent years, numerous aptamers have been physisorbed on graphene oxide (GO) to develop fluorescence resonance energy transfer-based aptasensors using the fluorescence quenching property of GO. However, physisorbed aptasensors show poor signal reversibility and reproducibility as well as nonspecific probe displacement, and thereby are not suitable for many analytical applications. To overcome these problems when working with complex biological samples, we developed a facile and robust covalent surface functionalization technique for GO-based fluorescent aptasensors using a well-studied adenosine triphosphate binding aptamer (ABA). In the scheme, GO is first modified with amino-silane, and further with glutaraldehyde to create available carbonyl groups for the covalent attachment of a fluorophore and an amino dual modified ABA. The surface modification method was characterized by ζ-potential, X-ray photoelectron spectroscopy, and Fourier-transform infrared spectroscopy (FTIR). The linearity, sensitivity, selectivity, and reversibility of the resulting GO-based covalent aptasensor was determined and systematically compared with the physisorbed aptasensor. Although both sensors showed similar performance in terms of sensitivity and linearity, better selectivity and higher resistance to nonspecific probe displacement was achieved with the developed covalent ABA sensor. The surface modification technique developed here is independent of the aptamer sequence, and therefore could be used universally for different analytical applications simply by changing the aptamer sequence for the target biomolecule.

One-pot synthesis of trifunctional chitosan-EDTA-β-cyclodextrin polymer for simultaneous removal of metals and organic micropollutants

The global contamination of water resources with inorganic and organic micropollutants, such as metals and pharmaceuticals, poses a critical threat to the environment and human health. Herein, we report on a bio-derived chitosan-EDTA-β-cyclodextrin (CS-ED-CD) trifunctional adsorbent fabricated via a facile and green one-pot synthesis method using EDTA as a cross-linker, for the adsorption of toxic metals and organic micropollutants from wastewater. In this system, chitosan chain is considered as the backbone, and the immobilized cyclodextrin cavities capture the organic compounds via host-guest inclusion complexation, while EDTA-groups complex metals. The thoroughly characterized CS-ED-CD was employed for batch adsorption experiments. The adsorbent displayed a monolayer adsorption capacity of 0.803, 1.258 mmol g-1 for Pb(II) and Cd(II) respectively, while a heterogeneous sorption capacity of 0.177, 0.142, 0.203, 0.149 mmol g-1 for bisphenol-S, ciprofloxacin, procaine, and imipramine, respectively. The adsorption mechanism was verified by FT-IR and elemental mapping. Importantly, the adsorbent perform is effective in the simultaneous removal of metals and organic pollutants at environmentally relevant concentrations. All these findings demonstrate the promise of CS-ED-CD for practical applications in the treatment of micropollutants. This work adds a new insight to design and preparation of efficient trifunctional adsorbents from sustainable materials for water purification.

A Schiff base/quaternary ammonium salt bifunctional graphene oxide as an efficient adsorbent for removal of Th(IV)/U(VI)

A novel approach for facile covalent functionalization of graphene oxide (GO) was proposed in the present study in order to effectively avoid necessary anhydrous conditions and the usage of harsh reagents during the chemical functionalization of GO. Herein, a GO derivative that was functionalized with a primary amine derivative bearing a positively charged quaternary ammonium group, GO-S, was synthesized through a Schiff base condensation reaction between the amine groups of the primary amine derivative and the aldehyde groups of GO. The introduction of the quaternary ammonium groups can prevent GO from stacking and improve the dispersibility of GO after modification. The formation of imine bonds (NCH) between the primary amine and GO has been confirmed by Fourier transform infrared and X-ray photoelectron spectroscopy. The GO-S demonstrated good dispersion stability in aqueous medium and also exhibited better adsorption performance than GO for Th(IV) and U(VI), with a maximum thorium adsorption capacity of 2.22mmol/g and a maximum uranium adsorption capacity of 0.83mmol/g, suggesting a great potential for the application of graphene oxide-based materials for facilitating the removal of Th(IV) and U(VI) from nuclear waste solutions.

Reduced Graphene Oxide-Reinforced Polymeric Films with Excellent Mechanical Robustness and Rapid and Highly Efficient Healing Properties

The fabrication of nanofiller-reinforced intrinsic healable polymer composite films with both excellent mechanical robustness and highly efficient healability is challenging because the mobility of the polymer chains is suppressed by the incorporated nanofillers. In this study, we exploit the reversible host-guest interactions between nanofillers and the matrix polymer films and report the fabrication of intrinsically healable, reduced graphene oxide (RGO)-reinforced polymer composite films capable of conveniently and repeatedly healing cuts of several tens of micrometers wide. The healable films can be prepared via layer-by-layer assembly of poly(acrylic acid) (PAA) with complexes of branched poly(ethylenimine) grafted with ferrocene (bPEI-Fc) and RGO nanosheets modified with β-cyclodextrin (RGO-CD) (denoted as bPEI-Fc&RGO-CD). The as-prepared PAA/bPEI-Fc&RGO-CD films are mechanically robust with a Young's modulus of 17.2 ± 1.9 GPa and a hardness of 1.00 ± 0.30 GPa. The healing process involves two steps: (i) healing of cuts in an oxidation condition in which the host-guest interactions between bPEI-Fc and RGO-CD nanosheets are broken and the cuts on the films are healed; and (ii) reconstruction of host-guest interactions between bPEI-Fc and RGO-CD nanosheets via reduction to restore the original mechanical robustness of the films.

Graphene-based nanomaterials for bioimaging

Graphene-based nanomaterials, due to their unique physicochemical properties, versatile surface functionalization, ultra-high surface area, and good biocompatibility, have attracted considerable interest in biomedical applications such as biosensors, drug delivery, bioimaging, theranostics, and so on. In this review, we will summarize the current advances in bioimaging of graphene-based nanomaterials, including graphene, graphene oxide (GO), reduced graphene oxide (rGO), graphene quantum dots (GQDs), and their derivatives. There are two methods to synthesize graphene-based nanomaterials: in situ synthesis and binding method. We will highlight the molecular imaging modalities including optical imaging (fluorescence (FL), two-photon FL, and Raman imaging), PET/SPECT (positron emission tomography/single photon emission computed tomography), MRI (magnetic resonance imaging), PAI (photoacoustic imaging), CT (computed tomography), and multimodal imaging. In the end, we will elaborate on the prospects and challenges of their future bioimaging applications.

Preparation of Highly Dispersed Reduced Graphene Oxide Modified with Carboxymethyl Chitosan for Highly Sensitive Detection of Trace Cu(II) in Water

In this article, reduced graphene oxide (RGO)/carboxymethyl chitosan (CMC) composites (RGO/CMC) were synthesized by a hydrothermal method through in-situ reduction and modification of graphene oxide (GO) in the presence of CMC. An electrochemical sensor for the determination of Cu(II) by differential pulse anodic stripping voltammetry (DPASV) was constructed by an electrode modified with RGO/CMC. The fabricated electrochemical sensor shows a linear range of 0.02⁻1.2 μmol·L^-1, a detection limit of 3.25 nmol·L^-1 (S/N = 3) and a sensitivity of 130.75 μA·μmol·L^-1·cm^-2, indicating the sensor has an excellent detection performance for Cu(II).

Non-covalent modification of reduced graphene oxide by a chiral liquid crystalline surfactant

In order to effectively disperse reduced graphene oxide (RGO) in functional materials and take full advantage of its exceptional physical and chemical properties, a novel and effective approach for non-covalent modification of RGO by a chiral liquid crystalline surfactant (CLCS) consisting of chiral mesogenic units, nematic mesogenic units with carboxyl groups and non-mesogenic units with a polycyclic conjugated structure is firstly established. The polycyclic conjugated structure can anchor onto the RGO surface via π-π interactions, the chiral mesogenic units possess affinity for chiral materials by joining the helical matrix of chiral material and the carboxyl groups in nematic mesogenic units are supposed to form coordination bonds with nano zinc oxide (ZnO) to fabricate functional nano hybrids. The transmittances of CLCS-RGO hybrids exhibit S-shaped nonlinear increase with the increase of wavelength, but the total transmittances from 220 nm to 800 nm show a linear decreasing trend with the increase of RGO content in the CLCS-RGO hybrid. Due to the superior thermal properties of RGO and the interactions between RGO and CLCS, the dispersed RGO can improve the glass transition and increase the thermal stability and decomposition activation energy of CLCS. The intercalation of RGO can decrease the thermochromism temperature and improve the pitch uniformity of CLCS. Furthermore, CLCS can promote the dispersion of RGO in chiral nematic liquid crystals (CNLCs), and the CNLC-RGO-CLCS hybrids present decreased driving voltage and accelerated electro-optical response. The CLCS non-covalently modified RGO can strengthen the photocatalytic degradation of ZnO by suppressing the aggregation of ZnO and RGO.

β-Cyclodextrin functionalized carbon quantum dots as sensors for determination of water-soluble C60 fullerenes in water

A selective photoluminescence method based on Carbon Quantum Dots (CQDs) functionalized with carboxymethyl-β-cyclodextrin for the direct determination of water-soluble C₆₀ fullerene has been developed.

A pH-driven molecular shuttle based on rotaxane-bridged periodic mesoporous organosilicas with responsive release of guests

A pH-driven molecular shuttle was immobilized into the framework of the PMOs in which the β-CDs could shuttle mechanically.

Applications of graphene and its derivatives in intracellular biosensing and bioimaging

Graphene has a unique planar structure, as well as excellent electronic properties, and has attracted a great deal of interest from scientists.

EDTA-Cross-Linked β-Cyclodextrin: An Environmentally Friendly Bifunctional Adsorbent for Simultaneous Adsorption of Metals and Cationic Dyes

The discharge of metals and dyes poses a serious threat to public health and the environment. What is worse, these two hazardous pollutants are often found to coexist in industrial wastewaters, making the treatment more challenging. Herein, we report an EDTA-cross-linked β-cyclodextrin (EDTA-β-CD) bifunctional adsorbent, which was fabricated by an easy and green approach through the polycondensation reaction of β-cyclodextrin with EDTA as a cross-linker, for simultaneous adsorption of metals and dyes. In this setting, cyclodextrin cavities are expected to capture dye molecules through the formation of inclusion complexes and EDTA units as the adsorption sites for metals. The adsorbent was characterized by FT-IR, elemental analysis, SEM, EDX, ζ-potential, and TGA. In a monocomponent system, the adsorption behaviors showed a monolayer adsorption capacity of 1.241 and 1.106 mmol g(-1) for Cu(II) and Cd(II), respectively, and a heterogeneous adsorption capacity of 0.262, 0.169, and 0.280 mmol g(-1) for Methylene Blue, Safranin O, and Crystal Violet, respectively. Interestingly, the Cu(II)-dye binary experiments showed adsorption enhancement of Cu(II), but no significant effect on dyes. The simultaneous adsorption mechanism was further confirmed by FT-IR, thermodynamic study, and elemental mapping. Overall, its facile and green fabrication, efficient sorption performance, and excellent reusability indicate that EDTA-β-CD has potential for practical applications in integrative and efficient treatment of coexistenting toxic pollutants.

A facile synthesis of a highly water-soluble and selective fluorescent sensor towards zinc ions derived from β-cyclodextrin based on an unexpected sensing process

A highly selective and sensitive fluorescent sensor for Zn²⁺ derived from a β-cyclodextrin derivate was fabricated. Through fluorescence micrograph experiments, the sensor showed an excellent image effect on onion epidermal cells.

A novel chiral electrochemiluminescence sensor that can discriminate proline enantiomers

A chiral stereoselective electrochemiluminescence (ECL) sensor was constructed by using Ru–AuNPs and β-CD–rGO composites to discriminate proline enantiomers.

Facile fabrication of three-dimensional graphene microspheres using β-cyclodextrin aggregates as substrates and their application for midecamycin sensing

Three-dimensional (3D) graphene (GR) microspheres have been successfully prepared for the first time using β-cyclodextrin aggregates (β-CDAs) as substrates, which could be easily obtained from concentrated aqueous solutions of β-CD.

Electrochemical biosensors on platforms of graphene

In recent years, graphene, the two-dimensional closely packed honeycomb carbon lattice, has been attracting much attention in the field of electrochemistry due to its intrinsic properties and merits. Efforts to create novel graphene based electrochemical biosensors have led to the establishment of effective strategies for diverse bioassays, from simple molecules to complex biotargets. In this Feature Article, we provide an overview of electrochemical biosensing with graphene related materials, and discuss the role of graphene in different sensing protocols.