Density Of Surface Functional Groups Research Articles

Development of Spiropyran Immobilization and Characterization Protocols for Reversible Photopatterning of SiO2 Surfaces.

Spiropyran is a dynamic organic compound that is distinguished by its reversible conversion between two forms: the colorless closed spiropyran (SP) form and the purple open merocyanine (MC) form. Typically triggered by UV light and reversed by visible light, spiropyran-functionalized surfaces offer reversible conversion in properties including color, polarity, reactivity, and fluorescence, making them applicable to diverse applications in chemical sensors, biosensors, drug delivery, and heavy metal extraction. While spiropyran has been successfully incorporated into various material platforms with SiO2 surfaces, its application on flat surfaces has been limited due to surface area constraints and a lack of standardized evaluation methods, which largely depend on the integration approach and substrate type used. In this study, we systematically review the existing literature and categorize integration methods and substrate types first and then report on our experimental work, in which we developed a streamlined three-step immobilization protocol, which includes surface activation, amination with (3-aminopropyl) triethoxysilane (APTES), and subsequent functionalization with carboxylic spiropyran (SP-COOH). Using SiO2 surfaces as a demonstration, we have also established a robust characterization protocol, consisting of contact angle measurements, X-ray photoelectron spectroscopy (XPS), ellipsometry, and fluorometric analysis. Our results evaluate the newly developed immobilization protocol, demonstrating effective activation and optimal amination using a 2% APTES solution, achieved in 5 min at room temperature. Fluorescence imaging provided clear contrast between the SP and the MC forms. Furthermore, we discuss limitations in the surface density of functional groups and steric hindrance and propose future improvements. Our work not only underscores the versatility of spiropyran in surface patterning but also provides optimized protocols for its immobilization and characterization on SiO2 surfaces, which may be adapted for use on other substrates. These advancements lay the groundwork for on-chip sensing technologies and other applications.

Redox-mediated changes in the release dynamics of lead (Pb) and bacterial community composition in a biochar amended soil contaminated with metal halide perovskite solar panel waste

This study explored the redox-mediated changes in a lead (Pb) contaminated soil (900 mg/kg) due to the addition of solar cell powder (SC) and investigated the impact of biochar derived from soft wood pellet (SWP) and oil seed rape straw (OSR) (5% w/w) on Pb immobilization using an automated biogeochemical microcosm system. The redox potential (Eh) of the untreated (control; SC) and biochar treated soils (SC + SWP and SC + OSR) ranged from −151 mV to +493 mV. In SC, the dissolved Pb concentrations were higher under oxic (up to 2.29 mg L−1) conditions than reducing (0.13 mg L−1) conditions. The addition of SWP and OSR to soil immobilized Pb, decreased dissolved concentration, which could be possibly due to the increase of pH, co-precipitation of Pb with FeMn (hydro)oxides and pyromorphite, and complexation with biochar surface functional groups. The ability and efficiency of OSR for Pb immobilization were higher than SWP, owing to the higher pH and density of surface functional groups of OSR than SWP. Biochar enhanced the relative abundance of Proteobacteria irrespective of Eh changes, while the relative abundance of Bacteroidota increased under oxidizing conditions. Overall, we found that both OSR and SWP immobilized Pb in solar panel waste contaminated soil under both oxidizing and reducing redox conditions which may mitigate the potential risk of Pb contamination.

Quantification of carboxylic binding sites on functionalized silicon nitride surface through X-ray photoelectron signal and fluorescence labelling

The wet-chemical functionalization of inorganic surfaces by organic bifunctional interlayers is a viable method towards the realization of optical (bio-)sensing devices. A detailed description of the organic-inorganic interface and a quantification of the surface functional group density is desirable, as they will determine the interaction of the transducer surface with the bioreceptor, thus final sensor efficiency. By characterizing surfaces at different sample preparation stages, we demonstrate that X-ray photoelectron spectroscopy (XPS) can be used to identify different coexisting carbon species at the interface as well as to quantify the packing density of the bifunctional interlayer. As a model system for proof-of-concept, the silicon nitride surface was functionalized with a dodecanoic acid molecule bearing a carboxylic end group, and the molecular packing density was quantified both via standard fluorescence-based labelling and XPS attenuation. Our combined approach identifies the fraction of bioreceptor-accessible and -inaccessible binding sites on the functionalized surface. This information will help to optimize the formation of dense layers of immobilized bioreceptors at the transducer surface.

A Study of V(IV/V) and V(II/III) Reactions on Carbon Based Electrodes

The vanadium redox flow battery (VRFB) is one of the most promising energy storage technologies for large scale commercialization. Carbon based electrodes, such as carbon felts or carbon paper, are used for V(II/III) and V(IV/V) reactions. To improve the vanadium redox reaction kinetics, the carbon electrodes are usually activated by a variety of methods such as thermal treatment, heteroatom doping, catalyst incorporation etc. [1] It is generally considered that surface functional group such as C–OH, C=O play an important role in vanadium redox reaction [1-6]. Even though there are reports showing higher surface functional group content e.g. total C–O content leads to improved vanadium redox reaction kinetics [2-6], qualitative correlation of the surface property of the carbon materials and the vanadium redox reaction is not reported. There is a need for fundamental understanding of the surface properties of the carbon electrodes and their relation with the reaction kinetics, including the key parameters that determine them.In this work, using cyclic voltammetry (CV), we studied the surface properties of a variety of carbon based electrodes (glassy carbon (GC), edge plane pyrolytic graphite, base plane pyrolitic graphite, graphite (from Pine Research, called graphite-Pine thereafter), graphite rod, and H2SO4 soaked graphite rod), and the V(II/III) and V(IV/V) reaction kinetics on these electrodes. The goal of soaking the graphite rod electrode in H2SO4 is to activate the electrode and make it comparable to the carbon felt electrode [1]. XPS was also used to analyze the functional group. The relationship between the surface properties and the reaction kinetic parameters was analyzed.Fig. 1 compares the cyclic voltammograms (CV) of the edge plane, basal plane graphite and GC electrodes in 2 M H2SO4. Two redox couples are observed, ascribed to C=O and COOH group redox peak respectively [7]. On basal plane electrode, these two redox peaks are less significant, and an extra reduction peak is observed at 0.24 V due to the C–OH reduction. On the GC electrode, the C=O redox peak is still discernable but the COOH redox peak is almost undetectable. A capacitance region appears between 0.6 – 0.75 V vs Ag/AgCl for all these electrodes. Similar features are observed with the graphite-Pine, graphite rod and H2SO4 soaked graphite rod electrodes with significantly enhanced redox peaks and larger capacitance. The H2SO4 soaked graphite rod electrode presents the highest surface functional group density and capacitance. XPS also shows that the H2SO4 soaked graphite rod electrode has the highest total C–O content.CV of V(IV/V) and V(II/III) were measured using these electrodes at different scan rates. Fig. 2 shows the CV of V(IV/V) reaction on these electrodes. The three graphite rod electrodes show better reversible feature than the edge plane, basal plane and GC electrodes. Diffusion coefficient, transfer coefficient and reaction rate constant were obtained from the CVs. The diffusion coefficient follows the sequence of soaked graphite rod > graphite rod > Graphite-Pine > Edge plane > GC > basal plane electrode. The transfer coefficient and reaction rate constant are also different for these electrodes. Similarly, the diffusion coefficient, transfer coefficient and reaction rate constant are obtained for the V(II/III) reaction. The diffusion coefficient and reaction rate constant for the V(II/III) reaction are smaller than that for the V(IV/V) reaction on the corresponding electrodes. For both V(IV/V) and V(II/III), a linear relationship was found for diffusion coefficient versus the logarithm of capacitance and C=O group functional group. Higher value of log(capacitance) and log(C=O density) leads to larger diffusion coefficient. However, there is no clear relationship between transfer coefficient, reaction rate constant vs capacitance or C=O density. It seems that the capacitance and C=O functional group density are the importance parameters determining the vanadium redox reaction kinetics.References He, Y. Lv, T. Zhang, Y. Zhu, L. Dai, S. Yao., W. Zhu, L. Wang, Chem. Eng. J., 427 (2022) 131680Zhang, J. Xia, Z. Li, H. Zhou, L. Liu, Z. Wu, X. Qiu, Electrochim. Acta 89 (2013) 429– 435Liu, L. Yang, Q. Xu, C. Yan, RSC Adv., 2014, 4, 55666Choi, H. Noh, S. Kim, R. Kim, R. Kim, J. Lee, J. Heo, H.-T. Kim, J. Energy Storage, 21 (2019) 321 – 327Eifert, R. Banerjee, Z. Jusys, R. Zeis, J. Electrochem. Soc., 165 (2018) A2577 – A2586Leuna, D. Priyadarshani, A. K. Tripathi, M. Neergat, J. Electroanal. Chem., 878 (2020) 114590K. Singh, M. Pahlevaninezhad, N. Yasri, E. P. L. Roberts, ChemSusChem 2021, 14, 2100–2111 Figure 1

Prediction of heavy metals adsorption by hydrochars and identification of critical factors using machine learning algorithms

Hydrochar has become a popular product for immobilizing heavy metals in water bodies. However, the relationships between the preparation conditions, hydrochar properties, adsorption conditions, heavy metal types, and the maximum adsorption capacity (Qm) of hydrochar are not adequately explored. Four artificial intelligence models were used in this study to predict the Qm of hydrochar and identify the key influencing factors. The gradient boosting decision tree (GBDT) showed excellent predictive capability for this study (R2 = 0.93, RMSE = 25.65). Hydrochar properties (37%) controlled heavy metal adsorption. Meanwhile, the optimal hydrochar properties were revealed, including the C, H, N, and O contents of 57.28–78.31%, 3.56–5.61%, 2.01–6.42%, and 20.78–25.37%. Higher hydrothermal temperatures (>220 °C) and longer hydrothermal time (>10 h) lead to the optimal type and density of surface functional groups for heavy metal adsorption, which increased the Qm values. This study has great potential for instructing industrial applications of hydrochar in treating heavy metal pollution.

Functional polymers for modeling the formation of biogenic calcium carbonate and the design of new materials

AbstractSkeletal elements of living organisms (bones, teeth, horns, frustules of diatomic algae, mollusk shells, sea urchin needles, and sponge spicules) are biogenic composite materials consisting of an inorganic part (calcium phosphate and carbonate, silica) and various organic compounds. The first step in the synthesis of these materials is the condensation of an inorganic precursor under the control of biopolymers capable of interacting with the growing inorganic particle. We studied formation of calcium carbonate in the presence of copolymers of acrylic acid, 1‐vinylimidazole and vinylamine. Some of the copolymers were new, so their acid–base properties were characterized. The polymers have an influence on the precipitation of CaCO3 in aqueous medium, and depending on the polymer structure and the polymer‐calcium ratio, composite precipitates or stable dispersions were obtained. Composite nanoparticles have a negative charge, and they can interact with polymer bases to form calcium‐organic composite materials. Calcium carbonate formation under the control of organic polymers is a chemical model of calcium skeletal growth in living nature. The resulting composites containing micrometer‐range CaCO3 particles are promising materials for the design of microstructured coatings with a high surface density of functional groups. Some of the polymers studied are not involved in the resulting material, but affect the morphology of CaCO3, forming particles in the micrometer range, which are promising as fillers for plastics.

Effects of process liquid recirculation on material properties of hydrochar and corresponding adsorption of cationic dye

Hydrochar has been gaining tremendous interest as adsorbent materials, however, change in material properties due to process liquid recirculation needs to be explored, since commercial hydrothermal carbonization (HTC) is likely to recycle HTC process liquid in order to preheat the feedstock as well as minimize the wastewater accumulation. Therefore, this study focused on the process liquid recirculation up to 9 times and evaluated how surface functionalities as well as Rhodamine B adsorption capacities change with the number of recycle. HTC of corn stover was performed at a fixed temperature (230 °C) and a fixed residence time (30 mins) with 50 wt% process liquid recirculation. Results indicate that the mass yield for control was 60.6 ± 0.9 wt% which was increased to 66.9 ± 0.0 wt% with HTC process liquid recirculation. Meanwhile, ash was concentrating with HTC process liquid recirculation (from 10.3 ± 1.1% to 13.9 ± 0.3%). The Brunauer, Emmett, and Teller (BET) surface area and total pore volume for control were 6.7 ± 0.1 m2/g and 9.8 × 10−3 cm3/g, respectively, which were increased to 7.4 ± 0.0 m2/g (recycle-1) - 10.8 ± 0.1 m2/g (recycle-9) and 12.4 × 10−3 cm3/g (recycle-1) − 17.3 × 10−3 cm3/g (recycle-9). However, Boehm titration revealed that the recycle-3 retained higher oxygen-containing surface functional group density (231.2 ± 3.9 µmol/g) than control (161.9 ± 2.5 µmol/g) and recycle-9 (132.2 ± 1.5 µmol/g). These morphological characteristics also reflect on the Rhodamine B adsorption capacities, where maximum equilibrium adsorption capacity was found for recycle-3 (30.7 mg/g) followed by recycle-9 (23.6 mg/g) and control (21.4 mg/g) and the adsorption isotherms were following combined Langmuir-Freundlich isotherm.

Optimizing bromide anchors for easy tethering of amines, nitriles and thiols in porous organic polymers towards enhanced CO2 capture

Porous organic polymers with labile leaving groups offer direct access to reactive functional groups, otherwise not permissible during network formation. In a one-step, open air, self-coupling reaction of tris bromomethyl benzene, we report highly porous, bromine rich C–C bonded porous polymers. Due to the steric nature of the monomer, restrictive crosslinking allowed pendent bromine groups to remain unreacted and provided rapid exchange into amines, nitriles, and thiols. This simple but powerful strategy yielded two isostructural but varying porosity and pendent group density polymers, allowing a comparative gas uptake study. Despite having lower surface area, the porous polymer formed at low temperature showed higher amination due to higher density of bromine groups. The polymers with more pendant groups resulted better CO 2 uptake performances than higher porosity polymers with less pendant groups. Although post-modification decreased surface area of materials, amine functionalization greatly improved the CO 2 uptake capacity. The ethylenediamine appended version exhibited 4.7 times increase in CO 2 uptake capacity with highest CO 2 /N 2 selectivity of 729 (298 K), and with an isosteric heat of 97 kJ mol −1 at zero coverage. • The one-step synthesis of bromine tethered C–C bonded nanoporous polymers. • The tuning of porosity and number of bromine anchors by changing reaction temperature. • Successful tailoring of benzyl bromides with amine, thiol, and nitrile moieties. • The density of surface functional groups exhibits higher impact on CO 2 adsorption performance than porosity.

Role of Surface Chemistry in the In Vitro Lung Response to Nanofibrillated Cellulose.

Wood-derived nanofibrillated cellulose (NFC) has emerged as a sustainable material with a wide range of applications and increasing presence in the market. Surface charges are introduced during the preparation of NFC to facilitate the defibrillation process, which may also alter the toxicological properties of NFC. In the present study, we examined the in vitro toxicity of NFCs with five surface chemistries: nonfunctionalized, carboxymethylated, phosphorylated, sulfoethylated, and hydroxypropyltrimethylammonium-substituted. The NFC samples were characterized for surface functional group density, surface charge, and fiber morphology. Fibril aggregates predominated in the nonfunctionalized NFC, while individual nanofibrils were observed in the functionalized NFCs. Differences in surface group density among the functionalized NFCs were reflected in the fiber thickness of these samples. In human bronchial epithelial (BEAS-2B) cells, all NFCs showed low cytotoxicity (CellTiter-GloVR luminescent cell viability assay) which never exceeded 10% at any exposure time. None of the NFCs induced genotoxic effects, as evaluated by the alkaline comet assay and the cytokinesis-block micronucleus assay. The nonfunctionalized and carboxymethylated NFCs were able to increase intracellular reactive oxygen species (ROS) formation (chloromethyl derivative of 2′,7′-dichlorodihydrofluorescein diacetate assay). However, ROS induction did not result in increased DNA or chromosome damage.

Fabrication of Magnetic Nanoparticles Integrated Carbon Matrix from Chrysopogon zizanioides Roots: Strong Dye Adsorption and Persulphate Assisted Photodegradation

Activated carbon with magnetic nanoparticles was prepared from the roots of Chrysopogon zizanioides by impregnating the biomass with Fe3+ followed by carbonization in a muffle furnace. To assist the carbonization process, Zn2+ ions were also taken along with ferric ions during impregnation. The pHZPC, density of surface functional groups, surface acidity constants and advanced characterizations like FT-IR, N2 adsorption-desorption isotherms, SEM with EDAX, DLS, XRD and VSM analysis were carried out. The adsorption and natural sunlight induced photooxidation of two cationic dyes, namely, methylene blue and rhodamine B in presence of potassium persulphate were studied by varying parameters like time, dye concentration, pH of the dye solution, amount of magnetic activated carbon and concentration of persulphate ions. The adsorption capacities of methylene blue and rhodamine B were found to be 5.97 and 0.96 mg/g, respectively. Photocatalytic oxidation of the dyes was very rapid in the presence of persulphate with the observed rate constants being 5.3 × 10–3 min–1 for methylene blue and 13.0 × 10–3 min–1 for rhodamine B. The magnetic activated carbon is found to be effective even after five successive degradation experiments.

One-step fabrication method of non-fouling amine-functionalized polyethylene glycol thin film using a single precursor through plasma-enhanced chemical vapor deposition

Fabrication methods to produce an amine-functionalized surface have been widely investigated as it is a promising substrate for biological studies, owing to its ability to stably immobilize various biomolecules. In this study, a biocompatible amine-functionalized polyethylene glycol (aPEG) thin film was fabricated by using plasma-enhanced chemical vapor deposition (PECVD) to overcome the disadvantages of the conventional wet process. A functionalized PEG diamine was used as a single precursor to simplify the fabrication process, and the relationship between the surface functional group density and the plasma power was investigated. Also, the surfaces of the functionalized thin films were quantitatively analyzed to determine the optimal fabrication condition that yields the most excellent surface amine density. The non-fouling resistance of the aPEG thin film and its applicability for biological applications was demonstrated by successfully immobilizing the matrix metalloproteinase-7 (MMP-7) enzyme, which is a well-known biomarker for cancers, with minimal non-specific adsorption (NSA). Our fabrication method was further applied to the modification of rather challenging substrates, including carbon paper, polyethylene terephthalate (PET) film, silicon wafer, polyvinylidene fluoride (PVDF), and successful modification was confirmed by the results of time-of-flight secondary ion mass spectrometry (ToF-SIMS) analysis. It is expected that our fabrication method can enable applications of the functionalized thin film in bioscience by presenting a versatile surface modification technique for deposition of biocompatible material onto various substrates, which can be potentially used in disease diagnosis, medical implants, and bioengineering.

Periodic surface functional group density on graphene via laser-induced substrate patterning at Si/SiO2 interface

Controlling the spatial distribution of functional groups on 2D materials on a micrometer scale and below represents a fascinating opportunity to achieve anisotropic (opto)electronic properties of these materials. Periodic patterns of covalent functionalization can lead to periodic potentials in the monolayer; however, creating such superstructures is very challenging. Here, we describe an original approach to the periodic functionalization of graphene induced by substrate patterning using a pulsed laser. Laser-induced periodic surface structures (LIPSS) are produced on silicon wafers with thermally-grown oxide layers. The irradiation conditions for the formation of LIPSS confined at the SiO2/Si interface have been unravelled. LIPSS imprint their periodicity to the reactivity of the monolayer graphene placed on the substrate via modulation of its local doping level. This method is clean, straightforward and scalable with high spatial resolution.

Mitochondrial delivery of microRNA mimic let-7b to NSCLC cells by PAMAM-based nanoparticles

Many biological mechanisms including cellular metabolism and cell death are regulated by mitochondria known as powerhouse of the cell. Recently, let-7b, a tumour-suppressor microRNA has been detected in mitochondria of human cells targeting several mitochondrial-encoded respiratory chain genes. Triphenylphosphonium cation (TPP) is one of the major classes of mitochondriotropics that possess the ability of specifically targeting the mitochondria. PAMAM dendrimers are one of the most available agents in gene delivery due to their well-defined and beneficial features such as large density of surface functional groups. Hyaluronic acid (HA), a natural polysaccharide has been demonstrated to have the abilities such as good biocompatibility and targeting CD44 overexpressed receptors on non-small cell lung cancer (NSCLC) cells. In this research, let-7b-PAMAM (G5)-TPP and let-7b-PAMAM (G5)-TPP-HA nano-carriers were designed to deliver let-7b miRNA mimic to NSCLC cells’ mitochondria as a novel way of cancer cells inhibition. Nano-carriers were capable of being successfully taken up by A549 cells and localised in mitochondria environment. Let-7b loaded nanoparticles reduced cell viability and induced apoptosis significantly. Expression of genes involved in mitochondrial oxidative function was decreased resulting in nanoparticles effect on mitochondria. Application of mitochondria targeted-miRNA delivery systems could regulate cellular functions to inhibit lung cancer.

Quantifying the influence of surface physico-chemical properties of biosorbents on heavy metal adsorption

Heavy metals present in industrial wastewater contribute to human and ecosystem health risk when discharged without proper treatment. Low-cost biosorbents with high metal-binding capacity are increasingly being utilized for the removal of heavy metals. Inherent physico-chemical properties of biosorbents significantly influence their adsorption capacity. Studies quantifying the influence exerted by these properties on adsorption capacity are scarce. This study quantifies the influence and relative importance of selected physico-chemical properties on the adsorption capacity of three divalent heavy metals; Cu2+, Cd2+ and Pb2+ using multivariate analysis. Twenty one biosorbent mixtures were created, systematically varying their physico-chemical properties using tea factory waste and coconut shell biochar. Their adsorption capacities were measured using batch sorption studies. The influence of physico-chemical properties on the adsorption capacity is comparable for all three metal cations. Regression models were developed to quantify the influence of physico-chemical parameters on the adsorption capacity based on regression coefficients. All models were found to have high reliability with R2 values above 0.98. Acidic surface functional groups were found to act as the key property that governs the adsorption capacity of Pb2+, Cu2+ and Cd2+. Carboxylic groups played a major role in the adsorption of Cu2+ and Pb2+, while lactonic groups were more important in providing binding sites to Cd2+. SSA failed to demonstrate a significant impact on the adsorption capacity of these three metals on its own when the biosorbent had a low surface functional group density.

Direct/Alternating Current Electrochemical Method for Removing and Recovering Heavy Metal from Water Using Graphene Oxide Electrode.

Treatment of heavy-metal pollution in both point-of-use water and industrial wastewater is critical in protecting human health and the environment. Current methods for heavy-metal treatment in both sources have limitations. For point-of-use water, current methods usually suffer from limited capacity and difficulties in spontaneously removing multiple heavy metals. For industrial wastewater, current methods greatly reduce the value of heavy metal by precipitating them as sludge which requires further treatment. Here we developed an electrochemical method that can treat both low-concentration and high-concentration heavy-metal pollution using either direct current (DC) or alternating current (AC) electrodeposition with graphene-oxide-modified carbon felt electrode (CF-GO). The graphene oxide provides a high density of surface functional groups to assist the electrodeposition. The electrodeposition method showed 2 orders of magnitude higher capacity (>29 g heavy metal for 1 g of graphene oxide) compared with traditional adsorption methods. For low levels of heavy-metal pollution in point-of-use water, DC electrodeposition with a CF-GO electrode can reduce single heavy-metal ion pollution (Cu, Cd, and Pb) as well as multiple ion mixtures to below safe water drinking levels. This method can tolerate a much wider range of heavy-metal pollution in point-of-use water than traditional adsorption methods. For high-level pollution in industrial wastewater, AC electrodeposition can recover >99.9% heavy-metal ions. By tuning the AC frequency and voltage, the electrodeposition method can further selectively recover Cu, Cd, and Pb separately, which adds values to the heavy-metal removal process.

Plasma polymer film designs through the eyes of ToF-SIMS.

Time-of-flight secondary ion mass spectrometry (ToF-SIMS) is increasingly used for the detailed chemical characterization of complex organic materials. Of particular interest in biointerface materials, it provides the accurate molecular information on their surface, a prerequisite for the understanding of subsequent interaction with biomaterials. Plasma polymer films are promising biointerface materials, as tuning the deposition parameters allows the control over film stability and density of surface functional groups. However, the optimization of these film properties not only requires a detailed characterization of the film chemistry, but also that of the deposition mechanisms. Here, ToF-SIMS is used within its different operation modes to investigate those on several plasma polymer film designs. The detailed information on surface molecular chemistry, interface conformation, vertical and lateral chemical and cross-linking gradients is gathered and linked to the underlying deposition mechanisms. In combination with other techniques, the interpretation and understanding of the final functional property of the films in terms of protein adsorption and site-specific binding is achieved.

Graphene as a functional layer for semiconducting carbon nanotube transistor sensors

Single-walled carbon nanotubes (SWCNTs) hold vast potential for future electronic devices due to their outstanding properties, however covalent functionalization often destroys the intrinsic properties of SWCNTs, thus limiting their full potential. Here, we demonstrate the fabrication of a functionalized graphene/semiconducting SWCNT (T@fG) heterostructured thin film transistor as a chemical sensor. In this structural configuration, graphene acts as an atom-thick, impermeable layer that can be covalently functionalized via facile diazonium chemistry to afford a high density of surface functional groups while protecting the underlying SWCNT network from chemical modification, even during a covalent chemical reaction. As a result, the highly functionalized carbon-based hybrid structure exhibits excellent transistor properties with a carrier mobility and ON/OFF ratio as high as 64 cm2/Vs and 5400, respectively. To demonstrate its use in potential applications, T@fG thin films were fabricated as aqueous ammonium sensors exhibiting a detection limit of 0.25 μM in a millimolar ionic strength solution, which is comparable with state-of-the-art aqueous ammonium nanosensors.

Dendrimers Effects on the Immune System: Insights into Toxicity and Therapeutic Utility

Dendrimers are hyperbranched polymeric nanomaterials increasingly used in research, industrial and biomedical applications. Establishing safety profile of these particles includes an understanding of their interactions with blood components and the immune system. Herein I review the literature demonstrating how tuning dendrimer physicochemical properties influences their interaction with erythrocytes, platelets, plasma proteins, complement and coagulation systems. Dendrimer immunogenicity, adjuvanticity, allergenicity, anti-inflammatory, immunosuppressive and antibacterial properties are also discussed. Dendrimers hemato- and immune- compatibility are determined by particle size, architecture, type and density of surface functional groups. Case studies from the literature are discussed to support this conclusion. The review also highlights questions which require more thorough investigation to fill the gaps in our understanding of immunological properties of dendrimers.

Effect of the Structure and Length of Flexible Chains on Dendrimers Grafted Fe3O4@SiO2/PAMAM Magnetic Nanocarriers for Lipase Immobilization

Polyamidoamine (PAMAM) dendrimers have been widely applied in biomacromolecule immobilization, catalysis carriers, gene therapy, and drug delivery. However, there is still a lack of systematic research about lipase and protein immobilized by PAMAM dendrimers. Herein, we used three types of amine reagents to graft dendritic macromolecules on Fe3O4 nanoparticles and obtained a variety of Fe3O4@SiO2/PAMAM magnetic nanocarriers with different generations. The density of surface functional groups, the structure, and the length (generation) of the flexible chain play an important role in immobilizing Candida rugosa lipase (CRL). As a result, hexamethylenediamine (HMD) grafted dendritic magnetic carriers with the fourth generation (Gc-4) exhibited a superior performance in terms of immobilizing CRL. Then, polyethylenimine (PEI) instead of HMD was grafted to the Gc-4 to obtain a higher activity with respect to immobilized CRL (955.53 U/g) and free lipase. Furthermore, the immobilized CRL improved its tolerability...

Role of surface chemistry in modified ACF (activated carbon fiber)-catalyzed peroxymonosulfate oxidation

A commercial activated carbon fiber (ACF-0) was modified by three different methods: nitration treatment (ACF-N), heat treatment (ACF-H) and heat treatment after nitration (ACF-NH), and the effects of textural and chemical properties on the ability of the metal-free ACF-catalyzed peroxymonosulfate (PMS) oxidation of Reactive Black 5 (RB5), an azo dye being difficultly adsorbed onto ACF, in aqueous solution were investigated in this work. Surface density of functional groups, surface area changes, surface morphology and the chemical state inside ACF samples were characterized by Boehm titration, N2 adsorption, scanning electron microscopy in couple with energy dispersive spectroscopy (SEM-EDS) and X-ray photoelectron spectroscopy (XPS), respectively. XPS spectra deconvolution was applied to figure out the importance of surface nitrogen-containing function groups. We found that π-π, pyridine and amine have promoting effect on the catalytic oxidation while the −NO2 has inhibitory effect on the ACF/PMS systems for RB5 destroy. Sustainability and renewability of the typical ACF-NH for catalytic oxidation of RB5 were also discussed in detail. Information about our conclusions are useful to control and improve the performance of ACF-catalyzed PMS oxidation for organic pollutants in wastewater treatment.