Surface Of Nanomaterials Research Articles

Photocatalytic hydrogen production on the surface of cadmium sulphide and other different doping nanomaterials dispersed on zinc oxide

Photocatalytic hydrogen production on the surface of cadmium sulphide and other different doping nanomaterials dispersed on zinc oxide

Poly(safranine T)-deep eutectic solvent/copper oxide nanoparticle-carbon nanotube nanocomposite modified electrode and its application to the simultaneous determination of hydroquinone and catechol

This work presents the combined use of safranine (SF) as a redox polymer and multiwalled carbon nanotubes (MWCNT)-copper oxide nanoparticles (CuO) in the development of a novel sensor for the simultaneous analysis of hydroquinone (HQ) and catechol (CAT). Electropolymerisation of SF was carried out in acid-doped ethaline deep eutectic solvent to prepare poly(safranine) (PSFEthaline) film electrodes with three different nanostructured architectures on pencil graphite electrodes (PGE) as electrode substrate. The polymerisation was done after nanomaterial surface modification to obtain PSFEthaline-HCl/MWCNT/PGE, PSFEthaline-HCl/CuO/PGE, and PSFEthaline-HCl/MWCNT-CuO/PGE. The synthesis, preparation, and characterisation of PSF film-coated electrodes were studied using cyclic voltammetry and electrochemical impedance spectroscopy to investigate the contribution of each nanomaterial on sensor performance. The best result for polymer film growth was obtained with PSF electrodeposited on MWCNT-CuO/PGE in HCl doped-ethaline. The analytical performance of the modified electrode was evaluated for electrochemical sensing of HQ and CAT by differential pulse voltammetry in aqueous Britton-Robinson buffer solution. Due to the combined effect of MWCNT-CuO nanocomposite film and PSF, the modified electrode sensor provided sensitive and selective detection of HQ and CAT with good peak separation. The simultaneousdetermination of HQ and CAT in both tap water and milk samples was successfully carried out to demonstrate the analytical applicability of the sensor. The sensor could be a promising analytical approach for monitoring the amount of HQ and CAT in real samples.

Adsorptive colorimetric determination of chromium(VI) ions at ultratrace levels using amine functionalized mesoporous silica

There is an urgent need for a rapid, affordable and sensitive analytical method for periodic monitoring of heavy metals in water bodies. Herein, we report for the first time a versatile method for ultratrace level metal detection based on colorimetric sensing. The method integrates preconcentration using a nanomaterial with a colorimetric assay performed directly on the metal-enriched nanomaterial surface. This method circumvents the need for tedious sample pre-processing steps and the complex development of colorimetric probes, thereby reducing the complexity of the analytical procedure. The efficacy of the proposed method was demonstrated for chromium(VI) ions detection in water samples. Amine functionalized mesoporous silica (AMS) obtained from a one-pot synthesis was utilized as a pre-concentration material. The structural and chemical analysis of AMS was conducted to confirm its physico-chemical properties. The pre-concentration conditions were optimized to maximise the colorimetric signal. AMS exhibited a discernible colour change from white to purple (visible to the naked eye) for trace Cr(VI) ions concentration as low as 0.5 μg L−1. This method shows high selectivity for Cr(VI) ions with no colorimetric signal from other metal ions. We believe our method of analysis has a high scope for de-centralized monitoring of organic/inorganic pollutants in resource-constrained settings.

Transformation of an Aqueous Micellar Phase to a Bilayer of Gemini Surfactants on Gold Nanoparticles: A Steady-State and Time-Resolved Fluorescence and Fluorescence Anisotropy Study by Tuning the Precise Locations of Probes

The present work reports the transformation of aqueous micelles of gemini surfactants (12-4-12,2Br– or 12-8-12,2Br–) to a bilayer of surfactants on the surface of gold nanoparticles (AuNPs) capped with citrate during their in situ synthesis. The synthesized AuNPs are characterized using surface plasmon resonance (SPR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), dynamic light scattering (DLS), scanning transmission electron microscopy (STEM), and high-resolution transmission electron microscopy (HR-TEM) techniques. The transformation of micelles to a surfactant bilayer with time is understood with the help of fluorescence measurements such as steady-state and time-resolved fluorescence and fluorescence anisotropy, probed by tuning the precise locations of two fluorophores, Coumarin-480 (C-480) and rhodamine 6G (Rh6G), present in the micelles. As the formation of AuNPs initiates, the dyes get relocated from micelles to a site near the NP surface, which results in fluorescence quenching and a decrease in lifetime due to the nanomaterial surface energy transfer (NSET) from the donor dye to the acceptor AuNPs. The results indicated that Rh6G lies close to the head groups of the surfactant in micelles. Fast segmental/tumbling motions of Rh6G in micelles/bilayers are primarily responsible for the decay of anisotropy to zero. Lateral diffusion is responsible for slow rotational relaxation. With the growth of rod/needle-shaped NPs, the average lifetime and rotational relaxation time increase with an increase in fluorescence intensity due to the transfer of dye molecules from the NP surface to the interior of the bilayer. A significant change in the weightage of the slow component of C-480 compared to that of Rh6G with the formation of the bilayer supports that the former dye is located deep inside the bilayer with an equal contribution to depolarization from both the rotational motions at equilibrium. The excitation wavelength-dependent rotational relaxation time of Rh6G in the bilayer supports the prolate ellipsoidal shape of AuNPs surrounded by the bilayer. This study can help understand the mechanism of drug loading in forming metal NP-based hybrid drug delivery systems in an aqueous micellar solution of gemini surfactants.

Superior uptake of Cu(II) from aquatic media via Y[formula omitted]O[formula omitted]-ZnO nanostructures

Y2O3-ZnO nanostructures with an effective surface area of 20.6 m2/g−1 and crystalline size of 15 nm were successfully synthesized through a solid-state procedure. The composition, crystallinity, surface characteristics, Raman shifting, chemical vibration binding and textural characteristics of the nanomaterials generated were determined using XRD, BET, Raman, FTIR, SEM-EDX and XPS techniques. The fabricated adsorbent Y2O3-ZnO was utilized to remove Cu(II) ions from an aqueous phase. Batch elimination experiments indicated that removing Cu(II) contaminants from the surface of the Y2O3-ZnO nanomaterial is pH-dependent, with the maximum removal occurring at pH = 5. Pseudo-second-order kinetics and the Langmuir hypothesis adequately characterize the absorptive removal of Cu(II) ions from the Y2O3-ZnO surface. After a 19-minute prep period, the nanocomposite’s maximal absorption capacity was measured to be 606 mg/g. The experiments demonstrated that Y2O3-ZnO is a highly effective adsorbent for removing Cu(II) ions from aqueous systems.

Synthesis, Characterization, and Electrochemical Sensing Applications of Bimetallic Oxide/Carbon Nanomaterials Hybrids

Bimetallic oxide/carbon nanomaterials hybrids were chemically synthesized and fully characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Field Emission Scanning Electron Microscopy (FESEM), High-resolution transmission electron microscopy (HRTEM), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The elemental analysis confirmed the successful formation of MnCo2O4/carbon nanomaterials. The fingerprint area of FTIR showed the incorporation of the metal oxides onto CNTs and GO surfaces. Morphological investigations of the hybrids, using FESEM and HRTEM, revealed the uniform distribution of bimetallic oxides nanostructures over the surface of carbon nanomaterials. Furthermore, electrochemical characteristics were explored using the CV and EIS. The obtained electrochemical results demonstrated significant improvements in the electrocatalytic properties, in addition to the direct and fast electron transfer provided by the modified surfaces whereas the MnCo2O4/CNTs were exploited for the nano-enzymatic amperometric detection of hydrogen peroxide as an example to show the promising applications of such nanomaterials in designing high-efficiency nano-sensors and biosensors.

Engineering Nanointerfaces of Au25 Clusters for Chaperone-Mediated Peptide Amyloidosis.

Synthetic nanomaterials possessing biomolecular-chaperone functions are good candidates for modulating physicochemical interactions in many bioapplications. Despite extensive research, no general principle to engineer nanomaterial surfaces is available to precisely manipulate biomolecular conformations and behaviors, greatly limiting attempts to develop high-performance nanochaperone materials. Here, we demonstrate that, by quantifying the length (-SCxR±, x = 3-11) and charges (R- = -COO-, R+ = -NH3+) of ligands on Au25 gold nanochaperones (AuNCs), simulating binding sites and affinities of amyloid-like peptides with AuNCs, and probing peptide folding and fibrillation in the presence of AuNCs, it is possible to precisely manipulate the peptides' conformations and, thus, their amyloidosis via customizing AuNCs nanointerfaces. We show that intermediate-length liganded AuNCs with a specific charge chaperone peptides' native conformations and thus inhibit their fibrillation, while other types of AuNCs destabilize peptides and promote their fibrillation. We offer a microscopic molecular insight into peptide identity on AuNCs and provide a guideline in customizing nanochaperones via manipulating their nanointerfaces.

Citrate-promoted dissolution of nanostructured manganese oxides: Implications for nano-enabled sustainable agriculture

Nanostructured manganese oxides (nano-MnOx) have shown great promises as versatile agrochemicals in nano-enabled sustainable agriculture, owing to the coupled benefits of controlled release of dissolved Mn2+, an essential nutrient needed by plants, and oxidative destruction of environmental organic pollutants. Here, we show that three δ-MnO2 nanomaterials consisting of nanosheet-assembled flower-like nanospheres not only exhibit greater kinetics in citrate-promoted dissolution, but also are less prone to passivation, compared with three α-MnO2 nanowire materials. The better performance of the δ-MnO2 nanomaterials can be attributed to their higher abundance of surface unsaturated Mn atoms–particularly Mn(III)–that is originated from their specific exposed facets and higher abundance of surface defects sites. Our results underline the great potential of modulating nanomaterial surface atomic configuration to improve their performance in sustainable agricultural applications.

Nanomaterials Aiming to Tackle Antibiotic-Resistant Bacteria.

The global health of humans is seriously affected by the dramatic increases in the resistance patterns of antimicrobials against virulent bacteria. From the statements released by the Centers for Disease Control and Prevention about the world entering a post-antibiotic era, and forecasts about human mortality due to bacterial infection being increased compared to cancer, the current body of literature indicates that emerging tools such as nanoparticles can be used against lethal infections caused by bacteria. Furthermore, a different concept of nanomaterial-based methods can cope with the hindrance faced by common antimicrobials, such as resistance to antibiotics. The current review focuses on different approaches to inhibiting bacterial infection using nanoparticles and aiding in the fabrication of antimicrobial nanotherapeutics by emphasizing the functionality of nanomaterial surface design and fabrication for antimicrobial cargo.

Stimuli-Responsive Liquid-Crystal-Infused Porous Surfaces for Manipulation of Underwater Gas Bubble Transport and Adhesion.

Biomimetic artificial surfaces that enable the manipulation of gas bubble mobility have been explored in a wide range of applications in nanomaterial synthesis, surface defouling, biomedical diagnostics, and therapeutics. Although many superhydrophobic surfaces and isotropic-lubricant-infused porous surfaces have been developed to manipulate gas bubbles, the simultaneous control over the adhesion and transport of gas bubbles underwater remains a challenge. Thermotropic liquid crystals (LCs), a class of structured fluids, provide an opportunity to tune the behavior of gas bubbles through LC mesophase transitions using a variety of external stimuli. Using this central idea, the design and synthesis of LC-infused porous surfaces (LCIPS) is reported and the effects of the LC mesophase on the transport and adhesion of gas bubbles on LCIPS immersed in water elucidated. LCIPS are demonstrated to be a promising class of surfaces with an unprecedented level of responsiveness and functionality, which enables the design of cyanobacteria-inspired object movement, smart catalysts, and bubble gating devices to sense and sort volatile organic compounds and control oxygen levels in biomimetic cell cultures.

Understanding the Significance of Sample Preparation in Studies of the Nanoparticle Metabolite Corona.

The adsorption of metabolites to the surface of nanomaterials is a growing area of interest in the field of bionanointeractions. Like its more-established protein counterpart, it is thought that the metabolite corona has a key role in the uptake, distribution, and toxicity of nanomaterials in organisms. Previous research has demonstrated that nanomaterials obtain a unique metabolite fingerprint when exposed to biological matrices; however, there have been some concerns raised over the reproducibility of bionanointeraction research due to challenges in dispersion of nanomaterials and their stability. As such, this work investigates a much-overlooked aspect of this field, i.e., sample preparation, which is vital to the accurate, reproducible, and informative analysis of the metabolite corona. The impact of elution buffer pH, volume, and ionic strength on the metabolite corona composition acquired by uncapped and polyvinylpyrrolidone (PVP)-capped TiO2 from mixtures of cationic and anionic metabolites was studied. We demonstrate the temporal evolution of the TiO2 metabolite corona and the recovery of the metabolite corona, which resulted from a complex biological matrix, in this case human plasma. This work also demonstrates that it is vital to optimize sample preparation for each nanomaterial being investigated, as the metabolite recovery from Fe3O4 and Dispex-capped TiO2 nanomaterials is significantly reduced compared to the aforementioned uncapped and PVP-capped TiO2 nanomaterials. These are important findings for future bionanointeraction studies, which is a rapidly emerging area of research in nanoscience.

High performance of nitrite electrochemical sensing based on Au-poly(thionine)-tin oxide/graphene nanosheets nanocomposites

A novel non-enzymatic nitrite (NO2−) electrochemical sensor was fabricated based on Au-poly(thionine) and tin oxide/graphene nanosheets (Au-PTH/SGN) nanocomposites. The morphology, composition and structure of the nanocomposites were characterized by Transmission electron microscopy, Energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy. And the results indicated that homogeneous Au NPs with a size of approximate 80 nm and network nanostructure of PTH were attached on the surface of SGN nanomaterials. It had been also verified to satisfactory electrochemical results. The linear range of the proposed sensor was five orders of magnitude wide with the range of 0.2–127.7 (R2 = 0.9991) and 127.7–2800 (R2 = 0.9983) μmol L−1, the detection limit was determined to be 0.06 μmol L−1 (S/N＝3) and the sensitivity were 61.92 and 43.19 μA (mmol L−1)−1 cm−2, respectively. Compared with the similar type of NO2− sensors previously reported, the linear range was expanded by at least an order of magnitude and the detection limit was kept at the same level as the lowest. Furthermore, the constructed Au-PTH/SGN/GCE displayed fast response, excellent stability, reproducibility, and high anti-interference ability for NO2− detection. Moreover, the as-proposed electrode was successfully applied for detecting NO2− in tap water and sewage samples with recoveries ranging from 97.3% to 103.0%97.3%-103.0% and 98.7–102.6%, respectively. The present work is expected to provide a useful route and reference for designing novel high performance electrochemical sensors and broaden the applications of sensors.

Adsorption of a wide variety of antibiotics on graphene-based nanomaterials: A modelling study

The knowledge on the sorption behaviour of antibiotics on nanomaterials is limited, especially regarding the reaction mechanism on the surface of carbon nanomaterials, which may determine both the adsorptive capacity and regeneration efficiency of graphene adsorbers. In this work, we used molecular modelling to generate the most comprehensive (to date) adsorption dataset for pristine and functionalised graphene interacting with 8 β-lactams, 3 macrolide, 12 quinolone, 4 tetracycline, 15 sulphonamide, trimethoprim, 2 lincosamide, 2 phenicole and 4 nitroimidazole antibiotics, and their transformation products in water and n-octanol. Results show that various non-covalent interactions that operate simultaneously, including van der Waals dispersion forces, π-interactions, hydrophobic interaction and hydrogen bonding, facilitate adsorption. The molecular properties of antibiotics and graphene/graphene oxide, as well as the composition of the background solution regulate the magnitude of these interactions. Our findings demonstrate that the most efficient method for the removal of antibiotics from aquatic environments is the use of graphene at environmental pH. The subsequent regeneration of the sorbent is best achieved through washing with slightly basic (pH 8–10) non-polar solvents. The obtained theoretical insights expand and complement experimental observations and provide important information that can contribute to further exploration into the adsorbent properties of graphene-based materials, and towards the development of predictive adsorption models.

Structural and Electrochemical Characteristics of Platinum Nanoparticles Supported on Various Carbon Carriers

Graphene-like materials have attracted significant attention as alternative catalyst carriers due to the broad possibilities of changing their shape, composition, and properties. In this study we investigated the structural and electrochemical characteristics of platinum electrocatalysts supported on reduced graphene oxide (rGO), including those modified with amine functionalities, nitrogen heteroatoms (rGO-Am), and oxygen enriched (rGO-O). Synthesis of Pt nanoparticles (20 wt.%) on the graphene-like nanomaterials surface was carried out using a modified polyol procedure. The Pt20/rGO-Am showed a lower Pt nanoparticles size together with high Pt utilization and EASA values compared to rGO-supported catalysts and the Pt/C reference sample due to the uniform distribution of nucleation centers on the surface of graphene nanoparticles, and the greater ability of these centers to electrically bond with platinum.

Delamination of MXenes using bovine serum albumin

Delamination of two-dimensional materials is a requisite step for exploiting their unique properties. Herein, we report on the formation of stable colloidal solutions of Ti3C2 and Mo2Ti2C3 MXene nanosheets by the dispersion and electrostatic exfoliation of stacked multilayer MXenes in the presence of albumin. Delamination of multilayered MXenes into atomically thin nanosheets resulted in stable colloidal solutions with good stability due to the adsorption of albumin, which prevents re-aggregation of the few-layer nanosheets. Cascading centrifugation was used to produce monodisperse colloids. This study demonstrates a processing method that can be utilized to prepare MXenes for biomedical applications. Since protein adsorption onto nanomaterial surfaces plays a significant role in many fields, including medicine, biology, pharmaceuticals, and environmental engineering, albumin coated MXenes may find many applications.

Nanomaterial Probes for Nuclear Imaging.

Nuclear imaging is a powerful non-invasive imaging technique that is rapidly developing in medical theranostics. Nuclear imaging requires radiolabeling isotopes for non-invasive imaging through the radioactive decay emission of the radionuclide. Nuclear imaging probes, commonly known as radiotracers, are radioisotope-labeled small molecules. Nanomaterials have shown potential as nuclear imaging probes for theranostic applications. By modifying the surface of nanomaterials, multifunctional radio-labeled nanomaterials can be obtained for in vivo biodistribution and targeting in initial animal imaging studies. Various surface modification strategies have been developed, and targeting moieties have been attached to the nanomaterials to render biocompatibility and enable specific targeting. Through integration of complementary imaging probes to a single nanoparticulate, multimodal molecular imaging can be performed as images with high sensitivity, resolution, and specificity. In this review, nanomaterial nuclear imaging probes including inorganic nanomaterials such as quantum dots (QDs), organic nanomaterials such as liposomes, and exosomes are summarized. These new developments in nanomaterials are expected to introduce a paradigm shift in nuclear imaging, thereby creating new opportunities for theranostic medical imaging tools.

Transforming Passive into Active: Multimodal Pheophytin-Based Carbon Dots Customize Protein Corona to Target Metastatic Breast Cancer.

Formation of protein corona on nanomaterials surface in vivo is usually considered as an unpredictable event for a predefined targeted delivery system for malignant cancers. In most situations, these protein coronas substantially change targeting efficiency or even cause adverse reactions which both hinder the clinical translation of the cargo-delivery systems. Active customization of protein corona onto nanomaterials surfaces can benefit their biomedical performances and open up new opportunities in construction of targeted delivery systems. Herein, lipid-PEG/pheophytin carbon dots (LPCDs) are prepared from natural chlorophyll and integrate seamlessly with positron emission tomography imaging, near-infrared fluorescence imaging, and photodynamic therapy capacity. In vitro measurements demonstrate that the LPCDs can actively absorb apolipoproteins into the protein corona to enhance their uptakes in breast cancer cells. In vivo studies confirm that LPCDs can give accurate delineation of metastatic breast cancer foci from surrounding normal tissues with multimodal biomedical functions. The feasibility of using LPCDs as a multimodal imaging and cancer-targeting nanoplatform may provide impetus for developing precise yet facile protein corona-targeted delivery systems for future clinical practice.

Carbon-based nanocoating for extended lifetime of conventional scale inhibitor squeeze treatment in sandstone reservoirs

Scale inhibition squeeze treatment is a common practice to prevent scale deposition within the downhole utilities, valve applications, and tubular components of the oil and gas producing wells. The conventional squeeze treatment has a short lifetime due to the reservoir rocks' limited adsorption of scale inhibitors and the quick desorption rate. As a result, this process has to be repeated multiple times per year, leading to massive increases in operational costs. Carbon-based nanomaterials are known for their high specific surface area, making them an attractive coating agent to enhance the capability of rocks’ surfaces to adsorb chemicals such as scale inhibitors. In this paper, carbon-based nanomaterials of graphene nanoplatelet (GNPs) and three different types of carbon nanotubes (CNTs) are proposed as novel nanocoating to extend the lifetime of the conventional scale inhibitor squeeze treatment. A natural polymer of Gum Arab (GA) was used to graft the nanomaterials surfaces to ensure a homogeneous and stabilized coating solution. The adsorption of diethylenetriamine penta (methylene phosphonic acid) (DTPMP) scale inhibitor into GNPs and CNTs was investigated using a UV–Vis spectrophotometer. Various characterization techniques such as FTIR, Raman spectroscopy, and XPS were performed to evaluate the interaction between DTPMP and the proposed nanocoating (GNPs/CNTs). Based on UV–Vis results, GNPs was found to be the optimal coating agent with an adsorption capacity of 135 mg/g at ambient temperature and 114 mg/g at 96 °C. Its coating gets saturated with DTPMP within 1 h of interaction. Increasing the initial scale inhibitor concentration was found to increase the adsorption capacity of GNPs. Based on the core flooding conducted on Berea sandstone, the injection of nanocoating into the core sample reduces the permeability by only 12%. Finally, the injected nanomaterial was safely transported through the core, and the primary retention mechanism was adsorption rather than physical filtration/plugging.

Influence of citrate and PEG coatings on the bioaccumulation of TiO2 and CeO2 nanoparticles following dietary exposure in rainbow trout

BackgroundThis study was conducted to provide much needed information on the potential of low solubility, highly biodurable nanoparticles (NPs) (TiO2 and CeO2 NPs), to bioaccumulate in fish and to investigate the relationship between an engineered nanomaterials surface coating, uptake and biokinetics in vivo. Rainbow trout (Oncorhynchus mykiss) were fed diets spiked with uncoated or surface coated (polyethylene glycol (PEG) or citrate (CIT)) TiO2 and CeO2 NPs (100 mg NPs/kg feed) for 10 days and thereafter fish were allowed to depurate for 42 days. Special care was taken to measure the real dispersed and actual administered concentrations, taking into consideration any potential losses from leaching, and to characterise the form (size, aggregation state, charge) of the NPs to which the fish were exposed.ResultsThe coatings had an influence on levels of uptake and distributions. Most notably a higher uptake of PEG and CIT coated TiO2 and CeO2 NPs compared to fish exposed to uncoated materials was observed. The elimination of any Ti from tissues was rapid during the first day of depuration, whereas Ce levels remained in fish tissues (stomach, intestine and liver) with differences in depuration and redistribution of the three types of CeO2 NPs. However, no bioaccumulation potential for both tested metal oxide NPs in fish irrespective of coatings is expected according to BMF values < 1.ConclusionsDistinct uptake, distribution and depuration kinetics in rainbow trout have been evidenced for different metal oxide NPs (TiO2 and CeO2 NPs). Coatings influenced uptake and in some cases led to slower depuration and distinct distributions, but do not make the uncoated NPs studied bioaccumulative (BMF > 1).Graphical

Haralick's texture analysis to predict cellular proliferation on randomly oriented electrospun nanomaterials.

Using a computer vision approach we have extracted the Haralick's texture features of randomly oriented electrospun nanomaterials in order to predict the proliferative behavior of cells which were subsequently seeded onto the nanosurfaces.