Several Aspects of Application of Nanodiamonds as Reinforcements for Metal Matrix Composites

Water treatment membranes embedded with a stable and bactericidal nanodiamond material

Filtration has emerged as a critical technology to reduce waterborne diseases caused by poor water quality. Filtration technology presents key challenges, such as membrane selectivity, permeability and biofouling. Nanomaterials can offer solutions to these challenges by varying the membranes' mechanical and bactericidal properties. This research uses nanodiamond particles with facile surface functionality and biocompatibility properties that are added to membranes used for filtration treatments. Scanning and transmission electron microscopy (SEM and TEM) and Fourier transform infrared spectroscopy (FTIR) were performed to study the membrane surface. FTIR spectra confirms an increase in oxygen functional groups onto the ultradispersed diamond's (UDD) surface following acid treatment. SEM images show particle deagglomeration of functionalized UDD at the membrane surface. Tensile strength tests were done to measure the UDD mechanical properties and Coliscan membrane filtration characterization was performed to determine the filter effectiveness. Polyether sulfone (PES) and polyvinylidene (PVDF) membranes expressed a change in their yield point when UDD was incorporated into the porous matrix. A significant microorganism reduction was obtained and confirmed using t-test analysis at a 95% level of confidence. UDD-embedded membranes exhibit a significant bactericidal reduction compared to commercial membranes suggesting these membranes have the potential to enhance current membrane filtration systems.

Nanoscale Tribological Properties of Nanostructure Fe3Al and (Fe,Ti)3Al Compounds Fabricated by Spark Plasma Sintering Method

Nanostructured powder particles of Fe3Al and (Fe,Ti)3Al phases were produced using mechanical alloying. These intermetallic phases with a nearly complete density were consolidated by spark plasma sintering. The mechanical properties of the bulk samples, i.e., elasticity modulus, hardness, and plasticity index, and also their tribological behavior were investigated using nanoindentation and nano-scratch tests. It was found that both Fe3Al and (Fe,Ti)3Al phases can be synthesized after 30 h of high-energy ball milling. In addition, no phase evolution was observed after spark plasma sintering. An analysis of the atomic force microscope images obtained from the nanoindentation tests showed a higher elasticity modulus, higher hardness, and lower plasticity index due to the addition of Ti to the Fe3Al system. (Fe,Ti)3Al displayed better tribological properties as compared with Fe3Al. A smaller volume of the scratched line was clearly seen in the atomic force microscope images of the nanostructured (Fe,Ti)3Al compound.

Characterization of Carbon Nanostructures by Photoelectron Spectroscopies

Recently, the scientific community experienced two revolutionary events. The first was the synthesis of single-layer graphene, which boosted research in many different areas. The second was the advent of quantum technologies with the promise to become pervasive in several aspects of everyday life. In this respect, diamonds and nanodiamonds are among the most promising materials to develop quantum devices. Graphene and nanodiamonds can be coupled with other carbon nanostructures to enhance specific properties or be properly functionalized to tune their quantum response. This contribution briefly explores photoelectron spectroscopies and, in particular, X-ray photoelectron spectroscopy (XPS) and then turns to the present applications of this technique for characterizing carbon nanomaterials. XPS is a qualitative and quantitative chemical analysis technique. It is surface-sensitive due to its limited sampling depth, which confines the analysis only to the outer few top-layers of the material surface. This enables researchers to understand the surface composition of the sample and how the chemistry influences its interaction with the environment. Although the chemical analysis remains the main information provided by XPS, modern instruments couple this information with spatial resolution and mapping or with the possibility to analyze the material in operando conditions at nearly atmospheric pressures. Examples of the application of photoelectron spectroscopies to the characterization of carbon nanostructures will be reviewed to present the potentialities of these techniques.

Nanodiamond conjugated SARS-CoV-2 spike protein: electrochemical impedance immunosensing on a gold microelectrode

A promising immunosensing strategy in diagnosing SARS-CoV-2 is proposed using a 10-µm gap-sized gold interdigitated electrode (AuIDE) to target the surface spike protein (SP). The microelectrode surface was modified by (3-glycidyloxypropyl) trimethoxysilane to enforce the epoxy matrix, which facilitates the immobilization of the anti-SP antibody. The immunosensing performance was evaluated by integrating a nanosized (~ 10 nm) diamond-complexed SP as a target. The proposed immunoassay was quantitatively evaluated through electrochemical impedance spectroscopy (EIS) with the swept frequency from 0.1 to 1 MHz using a 100 mV_RMS AC voltage supply. The immunoassay performed without diamond integration showed low sensitivity, with the lowest SP concentration measured at 1 pM at a determination coefficient of R² = 0.9681. In contrast, the nanodiamond-conjugated SP on the immunosensor showed excellent sensitivity with a determination coefficient of R² = 0.986. SP detection with a nanodiamond-conjugated target on AuIDE reached the low limit of detection at 189 fM in a linear detection range from 250 to 8000 fM. The specificity of the developed immunosensor was evaluated by interacting influenza-hemagglutinin and SARS-CoV-2-nucleocapsid protein with anti-SP. In addition, the authentic interaction of SP and anti-SP was validated by enzyme-linked immunosorbent assay.

Structure evolution of nanodiamond aggregates: a SANS and USANS study

Nanodiamonds (NDs) produced by two different techniques have been studied by ultra-small- (USANS) and small-angle neutron scattering (SANS): (i) produced by the detonation of explosives in an oxygen-deficient atmosphere (TNT + hexogen), which results in the production of detonation nanodiamonds, and (ii) produced by laser ablation of a carbon–hydro­carbon mixture. The size distribution of the particles and the composition of the outer layers are expected to vary depending on the source of the NDs.

Ultra-small-angle neutron scattering (USANS) and small-angle neutron scattering (SANS) measurements, covering length scales from micrometres to nanometres, were made to investigate the structure of nanodiamonds (NDs) and their suspensions. These nanodiamonds were produced by two different techniques, namely by the detonation method and by the laser ablation of a carbon–hydro­carbon mixture. The (U)SANS results indicated the presence of structures four orders of magnitude larger than the dimensions of a single ND particle, consisting of aggregations of ND particles. This aggregation of the ND particles was studied by employing the contrast variation technique. Two different solvents, namely H₂O and dimethyl sulfoxide (and their deuterated counterparts), were used to understand the role of hydrogen in the shape and size of the aggregates. The analysis of experimental data from SANS measurements also reveals the ND particles to have an ellipsoidal structure. Using a defined shape model and the SANS contrast variation technique, it was possible to characterize the non-diamond outer shell of the particles and determine the outer layer thickness. This clarification of the structure of the NDs will allow better preparation of suspensions/samples for various applications. Understanding the structure of NDs at multiple length scales also provides crucial knowledge of particle–particle interaction and its effect on the aggregation structures.