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The application of solar steam generation in seawater desalination is an effective way to solve the shortage of fresh water resources. At present, many kinds of photothermal conversion materials have been developed and used as evaporators in seawater desalination. However, some evaporators need additional thermal insulation or water supply devices to achieve efficient photothermal conversion. In addition, their complex, time consuming and no scalable preparation process, high cost of raw materials and poor salt resistance hinder the practical application of these evaporator. Owing to its distinctive nanoporous structure, diatomite as fossilized single-cells algae diatoms is a promising natural silica-based material for seawater desalination. They are taken from sea and that makes true sense to use them in the sea. Herein, we report the first example of synthesis robust three-dimensional (3D) natural-diatomite composite by assembling polyaniline nanoparticles covered diatomite into the polyvinyl alcohol pre-treated melamine foam frameworks and demonstrate its application as new evaporator for seawater desalination. The porous framework does not only improve the sunlight scattering efficiency, but also offer large network of channels for water transportation. The inherent mechanism behind salt desalination process involves the absorption of water molecules on the surface of the internal silica micro-nano pores, and evaporation under the heat induced by the polyaniline absorbed sunlight. Meanwhile, the metal ions are segregated by many available pores and channels to achieve the self-desalting effect. The developed evaporator possesses the superiority of multi-stage pore structure, strong hydrophilicity, low thermal conductivity, excellent light absorption, fast water transportation and salt-resistant crystallization as well as good durability. The evaporation rate without an additional device is found to be 1.689 kg m−2 h−1under 1-Sun irradiation, and the energy conversion efficiency is as high as 95%. This work creates a platform and develops the prospect of employing green and sustainable natural-diatomite composite evaporator for practical applications of seawater desalination.

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Research on graphene-related two-dimensional (2D) materials (GR2Ms) in recent years is strongly moving from academia to industrial sectors with many new developed products and devices on the market. Characterization and quality control of the GR2Ms and their properties are critical for growing industrial translation, which requires the development of appropriate and reliable analytical methods. These challenges are recognized by International Organization for Standardization (ISO 229) and International Electrotechnical Commission (IEC 113) committees to facilitate the development of these methods and standards which are currently in progress. Toward these efforts, the aim of this study was to perform an international interlaboratory comparison (ILC), conducted under Versailles Project on Advanced Materials and Standards (VAMAS) Technical Working Area (TWA) 41 “Graphene and Related 2D Materials” to evaluate the performance (reproducibility and confidence) of the thermogravimetric analysis (TGA) method as a potential new method for chemical characterization of GR2Ms. Three different types of representative and industrially manufactured GR2Ms samples, namely, pristine few-layer graphene (FLG), graphene oxide (GO), and reduced graphene oxide (rGO), were used and supplied to ILC participants to complete the study. The TGA method performance was evaluated by a series of measurements of selected parameters of the chemical and physical properties of these GR2Ms including the number of mass loss steps, thermal stability, temperature of maximum mass change rate (Tp) for each decomposition step, and the mass contents (%) of moisture, oxygen groups, carbon, and impurities (organic and non-combustible residue). TGA measurements determining these parameters were performed using the provided optimized TGA protocol on the same GR2Ms by 12 participants across academia, industry stakeholders, and national metrology institutes. This paper presents these results with corresponding statistical analysis showing low standard deviation and statistical conformity across all participants that confirm that the TGA method can be satisfactorily used for characterization of these parameters and the chemical characterization and quality control of GR2Ms. The common measurement uncertainty for each parameter, key contribution factors were identified with explanations and recommendations for their elimination and improvements toward their implementation for the development of the ISO/IEC standard for chemical characterization of GR2Ms.

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Magnesium oxide and hydroxide nanomaterials comprise a class of promising advanced functional metal nanomaterials whose use in environmental and material applications is increasing. Several strategies to synthesize these nanomaterials have been described but are unsustainable and uneconomic. This work reports on a processing strategy that turns natural magnesium-rich chrysotile into magnesium oxide and hydroxide nanoparticles via nanoparticle hybridization and an alkaline process while enabling La-based nanoparticles to coat the chrysotile nanotube surfaces. The adsorbent’s resulting hybrid nanostructure had an outstanding capacity for phosphate uptake (135.2 mg P g–1) and enhanced regeneration performance. Furthermore, the adsorbent featured wide applicability with respect to the coexistence of competitive anions and a broad range of pH conditions, and its high-performance phosphate removal from sewage effluent was also demonstrated. Spectroscopic and microscopic analyses revealed the scavenging ability of phosphate by the La-based and Mg-based nanoparticles and the multiple capture mechanisms involved, including surface complexation and ion exchange. This proposed approach expands chrysotile’s potential use as a magnesium-rich nanomaterial and harbors great promise for the removal of pollutants in a variety of real-world settings.

• Surface modification of Ti 3 C 2 T x MXene ink for 3D printing. • Improved interface interaction for PDMS/MXene stretchable conductors. • 3D printing of stretchable conductors with high self-supporting behaviour. • PDMS/MXene construct with appropriate stress-strain relations and electrical conductivity. Additive manufacturing has rapidly evolved over recent years with the advent of polymer inks and those inks containing novel nanomaterials. The compatibility of polymer inks with nanomaterial inks remains a great challenge. Simple yet effective methods for interface improvement are highly sought-after to significantly enhance the functional and mechanical properties of printed polymer nanocomposites. In this study, we developed and modified a Ti 3 C 2 MXene ink with a siloxane surfactant to provide compatibility with a polydimethylsiloxane (PDMS) matrix. The rheology of all the inks was investigated with parameters such as complex modulus and viscosity, confirming a self-supporting ink behaviour, whilst Fourier-transform infrared spectroscopy exposed the inks' reaction mechanisms. The modified MXene nanosheets have displayed strong interactions with PDMS over a wide strain amplitude. An electrical conductivity of 6.14 × 10−2 S cm−1 was recorded for a stretchable nanocomposite conductor containing the modified MXene ink. The nanocomposite revealed a nearly linear stress-strain relationship and a maximum stress of 0.25 MPa. Within 5% strain, the relative resistance change remained below 35% for up to 100 cycles, suggesting high flexibility, conductivity and mechanical resilience. This study creates a pathway for 3D printing conductive polymer/nanomaterial inks for multifunctional applications such as stretchable electronics and sensors. [ABSTRACT FROM AUTHOR]

The aerobic oxidation of 5-hydroxymethylfurfural (HMF), a key platform compound derived from biomass, to 2,5-furandicarboxylic acid (FDCA) is a highly important reaction in the production of green and sustainable chemicals. Here, we developed a highly efficient and stable halloysite-supported Pt–Au alloy catalyst for the selective oxidation of HMF to FDCA. The catalyst was synthesized through the organosilane functionalization of halloysite nanotubes, followed by the in situ formation and dispersion of Pt–Au alloy nanoparticles on the internal and external surfaces of nanotubes. The composition, morphology, and structure of the prepared catalyst were characterized. The catalyst with the optimal composition of Pt/Au molar ratio of 1/4 and metal loading of 1.5 wt % exhibited outstanding catalytic activity for the oxidation of HMF to FDCA using O2as an oxidant with 100% conversion of HMF and 99% selectivity of FDCA. This excellent catalytic performance is mainly attributed to the high dispersion and alloying effects of bimetallic nanoparticles, which promoted the activation of reactants or intermediates and further improved FDCA selectivity. Furthermore, the halloysite-supported Pt/Au bimetallic catalyst showed high stability and reusability. This study provides a promising strategy by combining clay mineral halloysite and bimetallic alloys for developing efficient catalysts with high FDCA selectivity and stability for the oxidation of HMF to FDCA.

ABSTRACTIntroduction:Titanium (Ti) and their alloys are used as main implant materials in orthopedics and dentistry for decades having superior mechanical properties, chemical stability and biocompatibility. Their rejections due lack of biointegration and bacterial infection are concerning with considerable healthcare costs and impacts on patients. To address these limitations, conventional Ti implants need improvements where the use of surface nanoengineering approaches and the development of a new generation of implants are recognized as promising strategies.Areas covered:This review presents an overview of recent progress on the application of surface engineering methods to advance Ti implants enable to address their key limitations. Several promising surface engineering strategies are presented and critically discussed to generate advanced surface properties and nano-topographies (tubular, porous, pillars) able not only to improve their biointegration, antibacterial performances, but also to provide multiple functions such as drug delivery, therapy, sensing, communication and health monitoring underpinning the development of new generation and smart medical implants.Expert opinion:Recent advances in cell biology, materials science, nanotechnology and additive manufacturing has progressively influencing improvements of conventional Ti implants toward the development of the next generation of implants with improved performances and multifunctionality. Current research and development are in early stage, but progressing with promising results and examples of moving into in-vivostudies an translation into real applications.

Counterfeits in the supply chain of high-value advanced materials such as graphene and their derivatives have become a concerning problem with a potential negative impact on this growing and emerging industry. Recent studies have revealed alarming facts that a large percentage of manufactured graphene materials on market are not graphene, raising considerable concerns for the end users. The common and recommended methods for the characterization of graphene materials, such as transmission electron microscopy (TEM), atomic force microscopy (AFM), and Raman spectroscopy based on spot analysis and probing properties of individual graphene particles, are limited to provide the determination of the properties of “bulk” graphene powders at a large scale and the identification of non-graphene components or purposely included additives. These limitations are creating counterfeit opportunities by adding low-cost black carbonaceous materials into manufactured graphene powders. To address this problem, it is critical to have reliable characterization methods, which can probe the specific properties of graphene powders at bulk scale, confirm their typical graphene signature, and detect the presence of unwanted additional compounds, where the thermogravimetric analysis (TGA) method is one of the most promising methods to perform this challenging task. This paper presents the evaluation of the TGA method and its ability to detect low-cost carbon additives such as graphite, carbon black, biochar, and activated carbon as potential counterfeiting materials to graphene materials and their derivatives such as graphene oxide (GO) and reduced GO. The superior performance of the TGA method is demonstrated here, showing its excellent capability to successfully detect these additives when mixed with graphene materials, which is not possible by two other comparative methods (Raman spectroscopy and powder X-ray diffraction (XRD)), which are used as the common characterization methods for graphene materials.

There is an increasing demand for low-cost and more efficient titanium (Ti) medical implants that will provide improved osseointegration and at the same time reduce the likelihood of infection. In the past decade, additive manufacturing (AM) using metal selective laser melting (SLM) or three-dimensional (3D) printing techniques has emerged to enable novel implant geometries or properties to overcome such potential challenges. This study presents a new surface engineering approach to create bioinspired multistructured surfaces on SLM-printed Ti alloy (Ti6Al4V) implants by combining SLM technology, electrochemical anodization, and hydrothermal (HT) processes. The resulting implants display unique surfaces with a distinctive dual micro- to nano-topography composed of micron-sized spherical features, fabricated by SLM and vertically aligned nanoscale pillar structures as a result of combining anodization and HT treatment. The fabricated implants enhanced hydroxyapatite-like mineral deposition from simulated body fluid (SBF) compared to control. In addition, normal human osteoblast-like cells (NHBCs) showed strong adhesion to the nano-/microstructures and displayed greater propensity to mineralize compared to control surfaces. This engineering approach and the resulting nature-inspired multiscale-structured surface offers desired features for improving osseointegration and antibacterial performance toward the development of next-generation orthopedic and dental implants.

A new strategy to produce phosphate (P) fertilizers with both fast and slowly soluble P by the compaction method to produce composite products is presented. This unique composition is created by combining monoammonium phosphate (MAP) as a highly soluble P nutrient source, with a commercially available slow-release P such as struvite (Str) or P-loaded graphene oxide (GO). Graphene oxide-loaded P was synthesized by in situ oxidation of GO and ferrous ion (GO-Fe) mixtures with hydrogen peroxide and further loading of P onto the GO-Fe composite. The nutrient release in water was studied for dual-release MAP-Str and MAP-GO-Fe-P and compared to their corresponding slow- and fast-release sources. Column perfusion experiments showed a biphasic dissolution behavior with no significant difference between MAP-GO-Fe-P and MAP-Str. Visualization of P diffusion and chemical analysis of the soil after diffusion were used to assess the diffusion of P from different P fertilizers in various types of soil. Runoff and leaching simulations were performed to investigate the effects of the prepared fertilizer formulations on the environment. Overall, the diffusion of the dual-release fertilizers and the P loss in runoff and leaching experiments were less than for MAP. The better environmental performance of the dual-release fertilizers compared to MAP was related to the specific properties of the GO-based materials such as their two-dimensional structure and to the low solubility of the Str in the case of Str-based fertilizers.

Engineering of multifunctional binding chemistry on graphene composites using thiol–ene click reaction for selective and highly efficient adsorption of mercury(II) is demonstrated. Graphene oxide (GO) is used as an initial material for covalent attachment of cysteamine molecules by thiol–ene click reaction on C═C groups to achieve a partially reduced graphene surface with multiple binding chemistry such as O, S, and N. Batch adsorption studies showed remarkable adsorption rate with only 1 mg L–1dosage of adsorbent used to remove 95% Hg (II) (∼1.5 mg L–1) within 90 min. The high adsorption capacity of 169 ± 19 mg g–1, high selectivity toward Hg in the presence of 30 times higher concentration of competing ions (Cd, Cu, Pb) and high regeneration ability (>97%) for five consecutive adsorption–desorption cycles were achieved. Comparative study with commercial activated carbon using spiked Hg (II) river water confirmed the high performance and potential of this adsorbent for real mercury remediation of environmental and drinking waters.

ABSTRACTIntroduction: Therapeutics delivery to bones to treat skeletal diseases or prevent postsurgical infections is challenging due to complex and solid bone structure that limits blood supply and diffusion of therapeutics administered by systemic routes to reach effective concentration. Titanium (Ti) and their alloys are employed as mainstream implant materials in orthopedics and dentistry; having superior mechanical/biocompatibility properties which could provide an alternative solution to address this problem.Areas covered: This review presents an overview of recent development of Ti drug-releasing implants, with emphasis on nanoengineered Titania nanotubes (TNTs) structures, for solving key problems to improve implants osseointegration, overcome inflammation and infection together with providing localized drug delivery (LDD) for bone diseases including cancer. Critical analysis of the advantages/disadvantages of developed concepts is discussed, their drug loading/releasing performances and specific applications.Expert opinion: LDD to bones can address many disorders and postsurgical conditions such as inflammation, implants rejection and infection. To this end, TNTs-Ti implants represent a potential promise for the development of new generation of multifunctional implants with drug release functions. Even this concept is extensively explored recently, there is a strong need for more preclinical studies using animal models to confirm the long-term safety and stability of TNTs-Ti implants for real-life medical applications.

Environmental contextPer- and poly-fluoroalkyl substances (PFASs) are contaminants of emerging concern, creating a need to develop efficient multi-functional adsorbents for improved remediation performance. By exploiting the versatility of graphene technology, we demonstrate that combining mineral and carbonaceous phases greatly increases and strengthens PFAS-binding to the adsorbent. The study highlights the benefits and potential applications of mixed adsorbents in PFAS-remediation. AbstractAs the degradation of perfluorooctanoic acid (PFOA) and related per- and poly-fluoroalkyl substances (PFASs) is energy-intensive, there is a need to develop in situ remediation strategies to manage PFAS-contamination. The sorption of PFOA by graphene oxide (GO), an iron-oxide-modified reduced-GO composite (FeG) and an activated-carbon(C)/clay/alumina-based adsorbent, RemBindTM (RemB), are evaluated. Sorption by FeG and RemB (>90%) is much greater than GO (60%). While an increase in pH hinders PFOA-sorption by GO, owing to the increased repulsion of anionic PFOA, variations in pH and ionic strength do not significantly influence PFOA-sorption by FeG and RemB, which indicates that binding is predominantly controlled by non-electrostatic forces. Hydrophobic interactions are assumed at the graphene or C-surface for all adsorbents, with added ligand-exchange mechanisms involving the associated Fe- and Al-minerals in FeG and RemB, respectively. Desorption of adsorbed PFOA is greatest in methanol, compared to water, toluene, or hexane, which provides estimates of the binding strength and reversibility from an environmental-partitioning perspective; i.e. risk of remobilisation of bound PFOA owing to rainfall events is low, but the presence of polar organic solvents may increase leaching risk. Iron-mineral-functionalisation of GO enhances the amount of PFOA adsorbed (by 30%) as well as the binding strength, which highlights the advantage of combining mineral and C-phases. Successful sorption of a range of PFASs from a contaminated-site water sample highlights the potential of using ‘mixed’ adsorbents like FeG and RemB in situ for PFAS-remediation, as they provide avenues for enhanced sorption through multiple mechanisms.

The environmental problems and low efficiency associated with conventional fertilizers provides an impetus to develop advanced fertilizers with slower release and better performances. Here, we report of development of a new carrier platform based on graphene oxide (GO) sheets that can provide a high loading of plant micronutrients with controllable slow release. To prove this concept, two micronutrients, zinc (Zn) and copper (Cu), were used to load on GO sheets and hence formulate GO-based micronutrients fertilizer. The chemical composition and successful loading of both nutrients on GO sheets were confirmed by X-ray photoelectron spectroscopy, thermogravimetric analysis, and X-ray diffraction (XRD). The prepared Zn-graphene oxide (Zn–GO) and Cu-graphene oxide (Cu–GO) fertilizers showed a biphasic dissolution behavior compared to that of commercial zinc sulfate and copper sulfate fertilizer granules, displaying desirable fast and slow micronutrient release. A visualization method and chemical analysis were used to assess the release and diffusion of Cu and Zn in soil from GO-based fertilizers compared with commercial soluble fertilizers to demonstrate the advantages of GO carriers and show their capability to be used as a generic platform for macro- and micronutrients delivery. A pot trial demonstrated that Zn and Cu uptake by wheat was higher when using GO-based fertilizers compared to that when using standard zinc or copper salts. This is the first report on the agronomic performance of GO-based slow-release fertilizer.

Graphene materials have been extensively explored and successfully used to improve performances of cement composites. These formulations were mainly optimized based on different dosages of graphene additives, but with lack of understanding of how other parameters such as surface chemistry, size, charge, and defects of graphene structures could impact the physiochemical and mechanical properties of the final material. This paper presents the first experimental study to evaluate the influence of oxygen functional groups of graphene and defectiveness of graphene structures on the axial tension and compression properties of graphene–cement mortar composites. A series of reduced graphene oxide (rGO) samples with different levels of oxygen groups (high, mild, and low) were prepared by the reduction of graphene oxide (GO) using different concentrations of hydrazine (wt %, 0.1, 0.15, 0.2, 0.3, and 0.4%) and different reduction times (5, 10, 15, 30, and 60 min) and were added to cement mortar composites at an optimal dosage of 0.1%. A series of characterization methods including scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, thermogravimetric analysis, and Fourier transform infrared spectroscopy were performed to determine the distribution and mixing of the prepared rGO in the cement matrix and were correlated with the observed mechanical properties of rGO–cement mortar composites. The measurement of the axial tension and compression properties revealed that the oxygen level of rGO additives has a significant influence on the mechanical properties of cement composites. An addition of 0.1% rGO prepared by 15 min reduction and 0.2% (wt %) hydrazine with mild level of oxygen groups resulted in a maximum enhancement of 45.0 and 83.7%, respectively, in the 28-day tensile and compressive strengths in comparison with the plain cement mortar and were higher compared to the composite prepared with GO (37.5 and 77.7%, respectively). These results indicate that there is a strong influence of the level of oxygen groups and crystallinity of graphene structures on the physiochemical and mechanical properties. The influence of these two parameters are interconnected and their careful balancing is required to provide an optimum level of oxygen groups on rGO sheets to ensure that there is sufficient bonding between the calcium silicate hydrate (C–S–H) components in the cement matrix and minimum level of defects and higher crystallinity of graphene structures, which will improve the mechanical properties of the composite. Finding the optimized balance between these two parameters is required to formulate graphene cement composites with the highest performance.

Carbon nanotubes (CNT) are increasingly being investigated for their use in biomedical applications and nanomedicine. In order to be used as nano-carriers for delivering anti-cancer drugs (drug delivery), smart free standing carbon nanotubes (CNTs) with hydrophilic core were prepared from recycled plastic bags. These CNTs were loaded with doxorubicin (Dox) and its external surface was chemically functionalized with a biodegradable polymer (chitosan) by anchoring its polymeric chains to functional groups on the external surface of CNTs. The obtained Chitosan-coated CNTs (Ch-CNCs) nanocomposites were then tested for their localized and slow drug eluting property using the cellular vicinity of MDA-MB-231 TXSA, human breast cancer cell line. The preliminary results are very promising and confirm a 500 fold enhanced death rate in case of cells treated with Ch-CNCs compared to the pro-drug alone. This work shows that it is possible to develop a highly biocompatible carbon nanocapsules (CNCs) derived from plastic bags and further used them as cargo transporters to study an intra-tumoral delivery of an anti-neoplastic drug is possible.

Primary and secondary bone cancers are major causes of pathological bone fractures which are usually treated through implant fixation and chemotherapy. However, both approaches face many limitations. On one hand, implants may suffer from poor osseointegration, and their rejection results in repeated surgery, patient’s suffering, and extensive expenses. On the other hand, there are severe systemic adverse effects of toxic chemotherapeutics which are administrated systemically. In this paper, in order to address these two problems, we present a new type of localized drug-releasing titanium implants with enhanced implants’ biointegration and drug release capabilities that could provide a high concentration of anticancer drugs locally to treat bone cancers. The implants are fabricated by 3D printing of Ti alloy followed by an anodization process featuring unique micro- (particles) and nanosurface (tubular arrays) topography. We successfully demonstrate their enhanced bone osseointegration and drug loading capabilities using two types of anticancer drugs, doxorubicin (DOX) and apoptosis-inducing ligand (Apo2L/TRAIL). In vitro study showed strong anticancer efficacy against cancer cells (MDA-MB-231-TXSA), confirming that these drug-releasing implants can be used for localized chemotherapy for treatment of primary and secondary bone cancers together with fracture support.

This work presents the synthesis of carbon nanotubes–nanoporous anodic alumina composite membranes (CNTs–NAAMs) with controllable geometric features by a template-assisted catalyst-free chemical vapor deposition (CVD) approach using a mixture of toluene and ethanol as a carbon precursor. NAAMs templates were prepared by anodization of aluminum substrates in different electrolytes containing sulfuric, oxalic, and phosphoric acids with the aim of establishing the template effect on the CNTs growth. The deposition time during the CVD process was systematically modified to determine the formation mechanism of CNTs inside the pores of NAAMs without using metal catalysts. The structural features, chemical composition, and graphitic structures of the resulting CNTs–NAAMs composites were characterized by different techniques to provide a comprehensive understanding of the effect of the template on the formation of these carbon-based nanostructures. CNTs–NAAMs with inner pore diameters ranging from 15 to 180 nm were used. Our results reveal that the electrolyte type used to prepare NAAMs and the deposition time during the CVD process have a direct impact on the structural, chemical, and graphitic structural features of CNTs–NAAMs. The molecular transport properties of CNTs–NAAMs composite membranes featuring different geometries and chemical compositions were evaluated via the diffusion process of Rose Bengal, a dye model molecule. The obtained results show that the diffusional flux of the dye molecules can be controlled by tuning the inner pore diameter of CNTs deposited inside NAAMs, and the smaller the diameter of the nanotubes the faster the transport of dye molecules is. Our results provide novel insights into the fabrication of different CNTs composite membranes, establishing for the first time the influence of three common types of NAAMs templates on the properties of the resulting CNTs composite membranes. Our study enables the precise engineering of advanced CNTs composite membranes with controlled physical and chemical properties suitable for specific applications.

Adhesion behavior of superhydrophobic (SH) surfaces is an active research field related to various engineering applications in controlled microdroplet transportation, self-cleaning, deicing, biochemical separation, tissue engineering, and water harvesting. Herein, we report a facile approach to control droplet adhesion, bouncing and rolling on properties of SH surfaces by tuning their air-gap and roughness-height by altering the concentrations of poly dimethyl-siloxane (PDMS). The optimal use of PDMS (4–16 wt %) in a dual-scale (nano- and microparticles) composite enables control of the specific surface area (SSA), pore volume, and roughness of matrices that result in a well-controlled adhesion between water droplets and SH surfaces. The sliding angles of these surfaces were tuned to be varied between 2 ± 1 and 87 ± 2°, which are attributed to the transformation of the contact type between droplet and surface from “point contact” to “area contact”. We further explored the effectiveness of these low and high adhesive SH surfaces in icing and deicing actions, which provides a new insight into design highly efficient and low-cost ice-release surface for cold temperature applications. Low adhesion (lotus effect) surface with higher pore-volume exhibited relatively excellent ice-release properties with significant icing delay ability principally attributed to the large air gap in the coating matrix than SH matrix with high adhesion (petal effect).

We explore new approaches to engineering the surface chemistry of interferometric sensing platforms based on nanoporous anodic alumina (NAA) and reflectometric interference spectroscopy (RIfS). Two surface engineering strategies are presented, namely (i) selective chemical functionalization of the inner surface of NAA pores with amine-terminated thiol molecules and (ii) selective chemical functionalization of the top surface of NAA with dithiol molecules. The strong molecular interaction of Au3+ions with thiol-containing functional molecules of alkane chain or peptide character provides a model sensing system with which to assess the sensitivity of these NAA platforms by both molecular feature and surface engineering. Changes in the effective optical thickness of the functionalized NAA photonic films (i.e., sensing principle), in response to gold ions, are monitored in real-time by RIfS. 6-Amino-1-hexanethiol (inner surface) and 1,6-hexanedithiol (top surface), the most sensitive functional molecules from approaches i and ii, respectively, were combined into a third sensing strategy whereby the NAA platforms are functionalized on both the top and inner surfaces concurrently. Engineering of the surface according to this approach resulted in an additive enhancement in sensitivity of up to 5-fold compared to previously reported systems. This study advances the rational engineering of surface chemistry for interferometric sensing on nanoporous platforms with potential applications for real-time monitoring of multiple analytes in dynamic environments.

ABSTRACTIntroduction: Drug delivery pertaining to acoustic cavitation generated from ultrasonic (US) irradiation is advantageous for devising smarter and more advanced therapeutics. The aim is to showcase microbubbles as drug carriers and robust theranostic for non-invasive therapies across diverse biomedical disciplines, highlighting recent technologies in this field for overcoming the blood-brain barrier (BBB) to treat cancers and neurological disorders.Areas covered: This article reviews work on the optimized tuning of ultrasonic parameters, sonoporation, transdermal and responsive drug delivery, acoustic cavitation in vasculature and oncology, contrast imaging for real-time magnification of cell-microbubble dynamics and biomolecular targeting. Scholarly literature was sought through database search on key terminology, latest topics, reputable experts and established journals over the last five years.Expert opinion: Cavitation offers immense promise in overcoming current diffusion and convection limitations for treating skull/brain/vascular/tissue injuries and ablating tumors to minimize chronic/acute effects. Since stable cavitation facilitates the restoration of US-opened BBB and the modulation of drug concentration, US equipment with programmable imaging modality and sensitivity are envisaged to create safer miniaturized devices for personalized care. Due to differing biomedical protocols with regard to specific medical conditions, quantitative and qualitative controls are mandatory before translation to real-life clinical applications can be accomplished.

Herein, the visible light‐photocatalytic performance of synthesized ZnO/Gr composite materials with different Gr content under various conditions, i.e., pH, dye concentration, and different scavengers (to understand the photocatalytic activity mechanism) is systematically investigated. Photocatalytic performance is evaluated with the degradation of methylene blue (MB) in solution under sunlight irradiation. The presence of graphene (Gr) in the ZnO/Gr composites shows enhanced photocatalytic activity compared to pure ZnO under natural sunlight illumination. The highest photodegradation efficiency of ≈94% when the content of Gr is 1 wt% in comparison to ≈76% for the pure ZnO, corresponding to reaction rate constants of 0.01038 and 0.00615 min−1, respectively. Compared to recent publications, the degradation efficiency is high with relatively high dye concentration, low catalyst amount, and large solution volume. The enhanced visible light absorption and the reduction of bandgap value are attributed to the enhanced photocatalytic properties of the hybridized composite. Moreover, the investigation of the effect of scavenger substances shows that H2O2strongly enhanced their photocatalytic ability, suggesting that holes (h+) contribute as the reactive agent in the photodegradation process. Hybrid materials of ZnO and graphene (Gr) are developed for photocatalytic application. The presence of 1 wt% Gr in the ZnO/Gr composites results in enhancing 18% photocatalytic activity under sunlight illumination. The enhanced visible light absorption and the reduction of bandgap value are attributed to the enhanced photocatalytic properties of the hybridized composite.

Naturally produced iron oxide nanowires by Mariprofundus ferrooxydansbacteria as biofilm are evaluated for their structural, chemical, and photocatalytic performance under visible-light irradiation. The crystal phase structure of this unique natural material presents a 1-dimensional (1D) nanowire-like geometry, which is transformed from amorphous to crystalline (hematite) by thermal annealing at high temperature without changing their morphology. This study systematically assesses the effect of different annealing temperatures on the photocatalytic activity of iron oxide nanowires produced by Mariprofundus ferrooxydansbacteria. The nanowires processed at 800 °C were the most optimal for photocatalytic applications degrading a model dye (rhodamine B) in less than an hour. These nanowires displayed excellent reusability with no significant loss of activity even after 6 cycles. Kinetic studies by using hydrogen peroxide (radical generator) and isopropyl alcohol (radical scavenger) suggest that OH• is the dominant photooxidant. These nanowires are naturally produced, inexpensive, highly active, stable, and magnetic and have the potential to be used for broad applications including environmental remediation, water disinfection, and industrial catalysis.

Here, we report a new method to prepare graphene from graphite by the liquid phase exfoliation process with sonication using graphene oxide (GO) as a dispersant. It was found that GO nanosheets act a as surfactant to the mediated exfoliation of graphite into a GO-adsorbed graphene complex in the aqueous solution, from which graphene was separated by an additional process. The preparation of isolated graphene from a single to a few layers is routinely achieved with an exfoliation yield of up to higher than 40% from the initial graphite material. The prepared graphene sheets showed a high quality (C/O ∼ 21.5), low defect (ID/IG∼ 0.12), and high conductivity (6.2 × 104S/m). Moreover, the large lateral size ranging from 5 to 10 μm of graphene, which is believed to be due to the shielding effect of GO avoiding damage under ultrasonic jets and cavitation formed by the sonication process. The thin graphene film prepared by the spray-coating technique showed a sheet resistance of 668 Ω/sq with a transmittance of 80% at 550 nm after annealing at 350 °C for 3 h. The transparent electrode was even greater with the resistance only 66.02 Ω when graphene is deposited on an interdigitated electrode (1 mm gap). Finally, a flexible sensor based on a graphene spray-coating polydimethylsiloxane (PDMS) is demonstrated showing excellent performance working under human touch pressure (<10 kPa). The graphene prepared by this method has some distinct properties showing it as a promising material for applications in electronics including thin film coatings, transparent electrodes, wearable electronics, human monitoring sensors, and RFID tags.

This study presents a sawtooth-like pulse anodization approach aiming to create a new type of photonic crystal structure based on nanoporous anodic alumina. This nanofabrication approach enables the engineering of the effective medium of nanoporous anodic alumina in a sawtooth-like manner with precision. The manipulation of various anodization parameters such as anodization period, anodization amplitude, number of anodization pulses, ramp ratio and pore widening time allows a precise control and fine-tuning of the optical properties (i.e., characteristic transmission peaks and interferometric colors) exhibited by nanoporous anodic alumina photonic crystals (NAA-PCs). The effect of these anodization parameters on the photonic properties of NAA-PCs is systematically evaluated for the establishment of a fabrication methodology toward NAA-PCs with tunable optical properties. The effective medium of the resulting NAA-PCs is demonstrated to be optimal for the development of optical sensing platforms in combination with reflectometric interference spectroscopy (RIfS). This application is demonstrated by monitoring in real-time the formation of monolayers of thiol molecules (11-mercaptoundecanoic acid) on the surface of gold-coated NAA-PCs. The obtained results reveal that the adsorption mechanism between thiol molecules and gold-coated NAA-PCs follows a Langmuir isotherm model, indicating a monolayer sorption mechanism.

The synthesis of a thiol-functionalized graphene composite with a unique three-dimensional porous structure composed of graphene nanosheets decorated with αFeOOH and porous silica microparticles (diatomaceous earth) is presented. The performance of this material for the removal of mercury ions (Hg2+) from water is evaluated using a batch adsorption and membrane separation approach. An outstanding adsorption performance of >800 mg g−1(at 400 mg L−1Hg2+) was demonstrated significantly exceeding currently available benchmark adsorbents. An excellent adsorption performance was confirmed for the efficient (~100%) removal of a low (4 mg L−1) and high (120 mg L−1) concentration of Hg in real water samples using this composite in the form of membranes. The results indicate the versatility of the developed composite to be used in different forms for several water purification scenarios (batch, column, membranes) relevant for both drinking and wastewater treatments. Based on their outstanding performance, low cost, and simple and scalable preparation, the presented 3D graphene composites have a considerable potential for the development of efficient and cost-competitive adsorbents and membranes for environmental applications.

This work presents the synthesis of carbon nanotubes (CNTs) inside titania nanotube (TNTs) templates by a catalyst-free chemical vapor deposition (CVD) approach as composite platforms for photocatalytic applications. The nanotubular structure of TNTs prepared by electrochemical anodization provides a unique platform to grow CNTs with precisely controlled geometric features. The formation mechanism of carbon nanotubes inside nanotubular titania without using metal catalysts is explored and explained. The structural features, crystalline structures, and chemical composition of the resulting CNTs–TNTs composites were systematically characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. The deposition time during CVD process was used to determine the formation mechanism of CNTs inside TNTs template. The photocatalytic properties of CNTs–TNTs composites were evaluated via the degradation of rhodamine B, an organic model molecule, in aqueous solution under mercury–xenon Hg (Xe) lamp irradiation monitored by UV–visible spectroscopy. The obtained results reveal that CNTs induces a synergestic effect on the photocatalytic activity of TNTs for rhodamine B degradation, opening new opportunities to develop advanced photocatalysts for environmental and energy applications.

Superhydrophobic surfaces for self-cleaning applications often suffer from mechanical instability and do not function well after abrasion/scratching. To address this problem, we present a method to prepare graphene-based superhydrophobic composite coatings with robust mechanical strength, self-cleaning, and barrier properties. A suspension has been formulated that contains a mixture of reduced graphene oxide (rGO) and diatomaceous earth (DE) modified with polydimethylsiloxane (PDMS) that can be applied on any surface using common coating methods such as spraying, brush painting, and dip coating. Inclusion of TiO2nanoparticles to the formulation shows further increase in water contact angle (WCA) from 159 ± 2° to 170 ± 2° due to the structural improvement with hierarchical surface roughness. Mechanical stability and durability of the coatings has been achieved by using a commercial adhesive to bond the superhydrophobic “paint” to various substrates. Excellent retention of superhydrophobicity was observed even after sandpaper abrasion and crosscut scratching. A potentiodynamic polarization study revealed excellent corrosion resistance (96.78%) properties, and an acid was used to provide further insight into coating barrier properties. The ease of application and remarkable properties of this graphene-based composite coating show considerable potential for broad application as a self-cleaning and protective layer.