Silver and Carbon Nanomaterials/Nanocomplexes as Safe and Effective ACE2-S Binding Blockers on Human Skin Cell Lines.

(1) Background: Angiotensin-converting enzyme 2 (ACE2) is a crucial functional receptor of the SARS-CoV-2 virus. Although the scale of infections is no longer at pandemic levels, there are still fatal cases. The potential of the virus to infect the skin raises questions about new preventive measures. In the context of anti-SARS-CoV-2 applications, the interactions of antimicrobial nanomaterials (silver, Ag; diamond, D; graphene oxide, GO and their complexes) were examined to assess their ability to affect whether ACE2 binds with the virus. (2) Methods: ACE2 inhibition competitive tests and in vitro treatments of primary human adult epidermal keratinocytes (HEKa) and primary human adult dermal fibroblasts (HDFa) were performed to assess the blocking capacity of nanomaterials/nanocomplexes and their toxicity to cells. (3) Results: The nanocomplexes exerted a synergistic effect compared to individual nanomaterials. HEKa cells were more sensitive than HDFa cells to Ag treatments and high concentrations of GO. Cytotoxic effects were not observed with D. In the complexes, both carbonic nanomaterials had a soothing effect against Ag. (4) Conclusions: The Ag5D10 and Ag5GO10 nanocomplexes seem to be most effective and safe for skin applications to combat SARS-CoV-2 infection by blocking ACE2-S binding. These nanocomplexes should be evaluated through prolonged in vivo exposure. The expected low specificity enables wider applications.

Dielectric Spectroscopy Analysis of Liquid Crystals Recovered from End-of-Life Liquid Crystal Displays.

In the present work, the dielectric properties of recycled liquid crystals (LCs) (non-purified, purified, and doped with diamond nanoparticles at 0.05, 0.1, and 0.2 wt%) were investigated. The studied LC mixtures were obtained from industrial recycling of end-of-life LC displays presenting mainly nematic phases. Dielectric measurements were carried out at room temperature on a frequency range from 0.1 to 106 Hz using an impedance analyzer. The amplitude of the oscillating voltage was fixed at 1 V using cells with homogeneous and homeotropic alignments. Results show that the dielectric anisotropy of all purified samples presents positive values and decreases after the addition of diamond nanoparticles to the LC mixtures. DC conductivity values were obtained by applying the universal law of dielectric response proposed by Jonscher. In addition, conductivity of the doped LC mixtures is lower than that of the undoped and non-purified LC.

Microscale-Resolution Thermal Mapping Using a Flexible Platform of Patterned Quantum Sensors.

Temperature sensors with micro- and nanoscale spatial resolution have long been explored for their potential to investigate the details of physical systems at an unprecedented scale. In particular, the rapid miniaturization of transistor technology, with its associated steep boost in power density, calls for sensors that accurately monitor heating distributions. Here, we report on a simple and scalable fabrication approach, based on directed self-assembly and transfer-printing techniques, to constructing arrays of nanodiamonds containing temperature-sensitive fluorescent spin defects. The nanoparticles are embedded within a low-thermal-conductivity matrix that allows for repeated use on a wide range of systems with minimal spurious effects. Additionally, we demonstrate access to a wide spectrum of array parameters ranging from sparser single-particle arrays, with the potential for quantum computing applications, to denser devices with 98 ± 0.8% yield and stronger photoluminescence signals, ideal for temperature measurements. With these, we experimentally reconstruct the temperature map of an operating coplanar waveguide to confirm the accuracy of these platforms.

Diamond Nanoparticles Downregulate Expression of CycD and CycE in Glioma Cells.

Our previous studies have shown that diamond nanoparticles (NDs) exhibited antiangiogenic and proapoptotic properties in vitro in glioblastoma multiforme (GBM) cells and in tumors in vivo. Moreover, NDs inhibited adhesion, leading to the suppression of migration and invasion of GBM. In the present study, we hypothesized that the NDs might also inhibit proliferation and cell cycle in glioma cells. Experiments were performed in vitro with the U87 and U118 lines of GBM cells, and for comparison, the Hs5 line of stromal cells (normal cells) after 24 h and 72 h of treatment. The analyses included cell morphology, cell death, viability, and cell cycle analysis, double timing assay, and gene expression (Rb, E2F1, CycA, CycB, CycD, CycE, PTEN, Ki-67). After 72 h of ND treatment, the expression level of Rb, CycD, and CycE in the U118 cells, and E2F1, CycD, and CycE in the U87 cells were significantly lower in comparison to those in the control group. We observed that decreased expression of cyclins inhibited the G1/S phase transition, arresting the cell cycle in the G0/G1 phase in glioma cells. The NDs did not affect the cell cycle as well as PTEN and Ki-67 expression in normal cells (Hs5), although it can be assumed that the NDs reduced proliferation and altered the cell cycle in fast dividing cells.

Diamond nanoparticles coating for in-tube solid-phase microextraction to detect polycyclic aromatic hydrocarbons.

Diamond nanoparticles were coated onto stainless steel wires as a extraction material, then it was filled into a poly(ether ether ketone) tube for in-tube solid-phase microextraction. Coupled with high-performance liquid chromatography, the extraction tube was evaluated with different types of analytes including polycyclic aromatic hydrocarbons, estrogens and plasticizers. As the coating, diamond nanoparticles exhibited greater extraction capacity for hydrophobic analytes. Several polycyclic aromatic hydrocarbons were used as model analytes, four main extraction and desorption factors were optimized, including sampling volume, sampling rate, methanol content in sample and desorption time. A sensitive analysis method was established with wide linear range (0.016-20 µg/L), good correlation coefficients (0.9991-0.9997), low limits of detection (0.005-0.020 µg/L), low limits of quantitation (0.016-0.070 µg/L) and high enrichment factors (305-2396). Relative standard deviations for intra- and interday were less than 2.4% (n = 3) and 8.4% (n = 3), respectively. Durability and chemical stability were satisfactory with relative standard deviations less than 7.9% (n = 3). Finally, the method has been successfully applied to the detection of polycyclic aromatic hydrocarbons in real samples.

Voltammetric sensing based on the use of advanced carbonaceous nanomaterials: a review.

This review (with 210 references) summarizes recent developments in the design of voltammetric chemical sensors and biosensors based on the use of carbon nanomaterials (CNMs). It is divided into subsections starting with an introduction into the field and a description of its current state. This is followed by a large section on various types of voltammetric sensors and biosensors using CNMs with subsections on sensors based on the use of carbon nanotubes, graphene, graphene oxides, graphene nanoribbons, fullerenes, ionic liquid composites with CNMs, carbon nanohorns, diamond nanoparticles, carbon dots, carbon nanofibers and mesoporous carbon. The third section gives conclusion and an outlook. Tables are presented on the application of such sensors to voltammetric detection of neurotransmitters, metabolites, dietary minerals, proteins, heavy metals, gaseous molecules, pharmaceuticals, environmental pollutants, food, beverages, cosmetics, commercial goods and drugs of abuse. The authors also describe advanced approaches for the fabrication of robust functional carbon nano(bio)sensors for voltammetric quantification of multiple targets. Graphical Abstract Featuring execellent electrical, catalytic and surface properies, CNMs have gained enormous attention for designing voltammetric sensors and biosensors. Functionalized CNM-modified electrode interfaces have demonstrated their prominent role in biological, environmental, pharmaceutical, chemical, food and industrial analysis.

Synergistic effect of MoS2 and diamond nanoparticles in electrochemical sensors: determination of the anticonvulsant drug valproic acid.

The authors describe an electrochemical sensor based on the use of diamond nanoparticles (DNPs) and molybdenum disulfide (MoS2) platelets. The sensor was applied to the voltammetric determination of the anticonvulsant valproic acid which was previously derivatized with ferrocene. The MoS2 platelets were obtained by an exfoliation method, and the DNPs were directly dispersed in water and subsequently deposited on a glassy carbon electrode (GCE). The sensor response was optimized in terms of the solvent employed for dispersing the MoS2 nanomaterial and the method for modifying the GCE. Sensors consisting of a first layer of MoS2 dispersed in ethanol/water and a second layer of DNPs give better response. The single steps of sensor construction were characterized by atomic force microscopy and electrochemical impedance spectroscopy. The differential pulse voltammetric response of the GCE (measured at +0.18 V vs. Ag/AgCl) was compared to that of sensors incorporating only one of the nanomateriales (DNPs or MoS2). The formation of a hybrid MoS2-DNP structure clearly improves performance. The GCE containing both nanomaterials exhibits high sensitivity (740 µA ⋅ mM-1 ⋅ cm-2), a 0.27 µM detection limit, and an 8% reproducibility (RSD). The sensor retained 99% of its initial response after 45 days of storage. Graphical abstract Electrochemical sensor by co-immobilization of MoS2 and diamond nanoparticles (DNP). The formation of a hybrid MoS2-DNP structure enhances the performance of the sensor towards valproic acid derivatized with a ferrocene group, when compared with sensors incorporating only DNP or MoS2.

Impact of diamond nanoparticles on neural cells.

Diamond nanoparticles (DNPs) are very attractive for biomedical applications, particularly for bioimaging. The aim of this study was to evaluate the impact of DNPs on neural cancer cells and thus to assess the possible application of DNPs for these cells imaging. For this purpose, the neuroblastoma SH-SY5Y cell line was chosen. Cells were cultured in medium with different concentrations (15, 50, 100 and 150 µg/ml) of DNPs. After 48 h of incubation, cell metabolic activity was evaluated by the XTT assay. For assessment of cellular metabolic activity, cells were also cultured on differently terminated nanocrystalline diamond (NCD) coatings in medium with 150 µg/ml of DNPs. Cell adhesion and morphology were evaluated by brightfield microscopy. Diamond nanoparticle internalization was determined by confocal microscopy. The obtained results showed that low concentrations (15, 50 and 100 µg/ml) of nanoparticles did not significantly affect the SH-SY5Y cell metabolic activity. However, a higher concentration (150 µg/ml) of DNPs statistically significantly reduced SH-SY5Y cell metabolic activity. After 48 h incubation with 150 µg/ml DNPs, cell metabolic activity was 23% lower than in medium without DNPs on standard tissue culture polystyrene.

Differences in the Cell Type-Specific Toxicity of Diamond Nanoparticles to Endothelial Cells Depending on the Exposure of the Cells to Nanoparticles.

Introduction: Diamond nanoparticles are considered to be one of the most cytocompatible carbon nanomaterials; however, their toxicity varies significantly depending on the analysed cell types. The aim was to investigate the specific sensitivity of endothelial cells to diamond nanoparticles dependent on exposure to nanoparticles. Methods: Diamond nanoparticles were characterized with Raman spectroscopy, Fourier-transform infrared spectroscopy (FTIR) and dynamic light scattering (DLS). Toxicity of diamond nanoparticles was assessed for endothelial cells (HUVEC), human mammary epithelial cells (HMEC) and HS-5 cell line. The effect of diamond nanoparticles on the level of ROS, NO, NADPH and protein synthesis of angiogenesis-related proteins of endothelial cells was evaluated. Results and Discussion: Our studies demonstrated severe cell type-specific toxicity of diamond nanoparticles to endothelial cells (HUVEC) depending on nanoparticle surface interaction with cells. Furthermore, we have assessed the effect on cytotoxicity of the bioconjugation of nanoparticles with a peptide containing the RGD motive and a serum protein corona. Our study suggests that the mechanical interaction of diamond nanoparticles with the endothelial cell membranes and the endocytosis of nanoparticles lead to the depletion of NADPH, resulting in an intensive synthesis of ROS and a decrease in the availability of NO. This leads to severe endothelial toxicity and a change in the protein profile, with changes in major angiogenesis-related proteins, including VEGF, bFGF, ANPT2/TIE-2, and MMP, and the production of stress-related proteins, such as IL-6 and IL-8. Conclusion: We confirmed the presence of a relationship between the toxicity of diamond nanoparticles and the level of cell exposure to nanoparticles and the nanoparticle surface. The results of the study give new insights into the conditioned toxicity of nanomaterials and their use in biomedical applications.

Dependence of diamond nanoparticle cytotoxicity on physicochemical parameters: comparative studies of glioblastoma, breast cancer, and hepatocellular carcinoma cell lines.

Reports on the cytotoxicity of diamond nanoparticles (ND) are ambiguous and depend on the physicochemical properties of the material and the tested cell lines. Thus, the aim of this research was to evaluate the influence of thirteen types of diamond nanoparticles, differing in production method, size, and surface functional groups, on their cytotoxicity against four tumor cell lines (T98G, U-118 MG, MCF-7, and Hep G2) and one non-tumor cell line (HFF-1). In order to understand the dependence of diamond nanoparticles on physicochemical properties, the following parameters were analyzed: viability, cell membrane damage, morphology, and the level of intracellular general ROS and mitochondrial superoxide. The performed analyses revealed that all diamond nanoparticles showed no toxicity to MCF-7, Hep G2, and HFF-1 cells. In contrast, the same nanomaterials were moderately toxic for the glioblastoma T98G and U-118 MG cell lines. In general, the effect of the production method did not influence ND toxicity. Some changes in cell response after treatment with modified nanomaterials were observed, with the presence of carboxyl groups having a more detrimental effect than the presence of other functional groups. Although nanoparticles of different sizes caused similar toxicity, nanomaterials with bigger particles caused a more pronounced effect.

Synergistic effect of manganese (II) phosphate & diamond nanoparticles in electrochemical sensors for reactive oxygen species determination in seminal plasma.

In this work, we explore the ability of manganese (II) phosphate (MnP) as a catalytic element for the determination of reactive oxygen species (ROS) in seminal plasma, when MnP is employed as modifier of a glassy carbon electrode. The electrochemical response of the manganese (II) phosphate-modified electrode shows a wave at around +0.65 V due to the oxidation of Mn2+ to MnO2+, which is clearly enhanced after addition of superoxide, the molecule considered as the mother of ROS. Once proved the suitability of manganese (II) phosphate as catalyst, we evaluate the effect of including a 0D (diamond nanoparticles) or a 2D (ReS2) nanomaterial in the sensor design. The system consisting of manganese (II) phosphate and diamond nanoparticles yielded the largest improvement of the response. The morphological characterization of the sensor surface was performed by scanning electron microscopy and atomic force microscopy, while cyclic and differential pulse voltammetry were employed for the electrochemical characterization of the sensor. After optimizing the sensor construction, calibration procedures by chronoamperometry were performed, leading to a linear relation between peak intensity and the superoxide concentration in the range of 1.1 10-4 M - 1.0 10-3 M with a limit of detection of 3.2 10-5 M. Seminal plasma samples were analysed by the standard addition method. Moreover, the analysis of samples fortified with superoxide at the µM level leads to recoveries of 95%.

2D-ReS2 & diamond nanoparticles-based sensor for the simultaneous determination of sunset yellow and tartrazine in a multiple-pulse amperometry FIA system.

We present a flow injection system with a multiple pulse amperometric detection (FIA-MPA)-based methodology for the simultaneous analysis of sunset yellow and tartrazine. As transducer, we have developed a novel electrochemical sensor based on the synergistic effect of ReS2 nanosheets and diamond nanoparticles (DNPs). Among several transition dichalcogenides for the sensor development, we have selected ReS2 nanosheets since it yields a better response towards both colourants. Scanning probe microscopy characterization shows that the surface sensor is composed by scattered and stacked ReS2 flakes and large aggregates of DNPs. With this system, the gap between the oxidation potential values of sunset yellow and tartrazine is wide enough to allow the simultaneous determination of both dyes. Under the optimum potential pulse conditions (0.8 and 1.2 V) during 250 ms, a flow rate of 3 mL/min and a volume injection of 250 µL, detection limits of 3.51 × 10-7 M and 2.39 × 10-7 M for sunset yellow and tartrazine, respectively, were obtained. This method exhibits good accuracy and precision with Er minor than 13% and RSD lower than 8% with a sampling frequency of 66 samples per hour. Pineapple jelly samples were analyzed by the standard addition method, obtaining 53.7 mg/kg and 29.0 mg/kg of sunset yellow and tartrazine, respectively. From the analysis of fortified samples, recoveries of 94% and 105% were obtained.

Assessment of the Mechanical and Corrosion Properties of Mg-1Zn-0.6Ca/Diamond Nanocomposites for Biomedical Applications.

In this work, the microstructure, mechanical properties, and corrosion behavior of the Mg-1Zn-0.6Ca matrix alloy (ZX10), reinforced by adding various amounts of nanodiamond particles (0.5, 1, and 2 wt.%), prepared by the ultrasound-assisted stir-casting method, were investigated as they are deemed as potential implant materials in biomedical applications. Microstructure, nanoindentation, mechanical tensile, immersion, and potentiodynamic polarization tests were performed for evaluating the influence of the addition of nanodiamond particles on the alloy's mechanical and biocorrosion properties. The results revealed that the addition of nanodiamond particles causes a reduction in the alloy's grain size. The alloy's nanohardness and elastic modulus values increased when the amount of added nanodiamond particles were increased. The nanocomposite with an addition of 0.5% ND showed the best composition with regard to an acceptable corrosion rate as the corrosion rates are too high with higher additions of 1 or 2% NDs. At the same time, the yield strength, tensile strength, and elongation improved slightly compared to the matrix alloy.

Rapid Generation of Coronaviral Immunity Using Recombinant Peptide Modified Nanodiamonds.

Vaccination remains one of the most effective tools to prevent infectious diseases. To ensure that the best possible antigenic components are chosen to stimulate a cognitive immune response, boosting antigen presentation using adjuvants is common practice. Nanodiamond-based adjuvants are proposed here as a rapid and versatile platform for antigen conjugation, utilizing peptides common to different pathogenic strains and making this strategy a good candidate for a "ready-to-use" vaccine. Initiation of an inflammatory reaction with a resulting immune response is based on the ability of living organisms to entrap nanostructures such as nanodiamonds with neutrophil extracellular traps (NETs) formation. In this work, coronavirus peptide homological for MERS-CoV, fusion inhibitor, was conjugated to nanodiamonds and used to induce neutrophilic-driven self-limiting inflammation. The resulting adjuvant was safe and did not induce any tissue damage at the site of injection. Mice immunization resulted in IgG titers of »,000 within 28 days. Immunization of rabbits resulted in the formation of a high level of antibodies persistently present for up to 120 days after the first immunization (animal lifespan ~3 years). The peptide used for immunization proved to be reactive with sera of convalescent COVID patients, demonstrating the possibility of developing pancoronaviral vaccine candidates.

Effects of Coenzyme Q10 and Diamond Nanoparticles on Ischemia-Reperfusion-Induced Testicular Damages in Rats.

Background: Ischemia-reperfusion (I/R) induced by testicular torsion can damage the testicles. In the present study, we assessed the effects of coenzyme Q10 (CoQ10) and diamond nanoparticles on sperm parameters in I/R testes in rats. Materials and Methods: Forty-eight Wistar adult male rats were divided into eight groups: healthy control (Ch), diamond nanoparticle healthy control group (Ch+Dia), CoQ10 healthy control group (Ch+Q10), diamond nanoparticles+CoQ10 healthy control group (Ch+Q10+Dia), torsion/detorsion group (Ct), the Ct group that received diamond nanoparticles (Ct+Dia), the Ct group that received CoQ10 (Ct+Q10), and Ct group that received diamond nanoparticles and CoQ10 (Ct+Q10+Dia). The rats were euthanized, and we collected the semen from the epididymal tissues to evaluate sperm viability, motility, concentration, and morphology parameters. Results: The I/R of the testicles significantly reduced sperm concentration, motility, viability, and altered sperm morphology in the rats. However, the administration of CoQ10 significantly improved sperm parameters in the rats with testicular I/R. Diamond nanoparticles decreased the sperm parameters; however, simultaneous administration of diamond nanoparticles and CoQ10 led to improved sperm parameters. Conclusion: CoQ10 potentially appeared to have protective effects against the long-term side-effects of I/R in testes in rats. Co-administration of diamond nanoparticles with CoQ10 significantly improved sperm parameters and greatly reduced the negative effects of diamond nanoparticles alone. Therefore, green synthesis of nanoparticles with the use of antioxidants such as CoQ10 is recommended.

A supramolecular hybrid sensor based on cucurbit[8]uril, 2D-molibdenum disulphide and diamond nanoparticles towards methyl viologen analysis.

We develop an electrochemical sensor by using 2D-transition metal dichalcogenides (TMD), specifically MoS2, and nanoparticles stabilized with cucurbit[8]uril (CB[8]) incorporated together with them. Two different nanoparticles are assayed: diamond nanoparticles (DNPs) and gold nanoparticles (AuNp). 0D materials, together with TMD, provide increased conductivity and active surface while the macrocycle CB[8] affords selectivity towards the guest methyl viologen (MV2+), also named paraquat. Glassy Carbon (GC) electrodes are modified by drop-casting of suspensions of MoS2, followed by either a CB[8]-DNPs hybrid dispersion or a CB[8]-AuNp suspension. Atomic force microscopy is employed for the morphological characterization of the electrochemical sensor surface while cyclic voltammetry and electrochemical impedance spectroscopy techniques allow the electrochemical characterization of the sensor. The well-stablished signals of CB[8]-encapsulated MV2+ arise in voltammetric measurements when the macrocycle modifies the 0D-materials. Once the sensor construction and differential pulse voltammetry parameters have been optimized for quantification purposes, calibration procedures are performed with the platform GC/MoS2/CB[8]-DNPs. This sensing platform shows linear relations between peak intensity and the MV2+ concentration in the linear concentration range of (0.73-8.0) · 10-6 M with a limit of detection of 2.2 · 10-7 M. Analyses of river water samples fortified with MV2+ at the µM level shows recoveries of 100% with RSD values of 6.4% (n = 3).

Electrospinning Fabrication and Cytocompatibility Investigation of Nanodiamond Particles-Gelatin Fibrous Tubular Scaffolds for Nerve Regeneration.

This paper reports the electrospinning fabrication of flexible nanostructured tubular scaffolds, based on fish gelatin (FG) and nanodiamond nanoparticles (NDs), and their cytocompatibility with murine neural stem cells. The effects of both nanofiller and protein concentration on the scaffold morphology, aqueous affinity, size modification at rehydration, and degradation are assessed. Our findings indicate that nanostructuring with low amounts of NDs may modify the fiber properties, including a certain regional parallel orientation of fiber segments. NE-4C cells form dense clusters that strongly adhere to the surface of FG50-based scaffolds, while also increasing FG concentration and adding NDs favor cellular infiltration into the flexible fibrous FG70_NDs nanocomposite. This research illustrates the potential of nanostructured NDs-FG fibers as scaffolds for nerve repair and regeneration. We also emphasize the importance of further understanding the effect of the nanofiller-protein interphase on the microstructure and properties of electrospun fibers and on cell-interactivity.

Selective cytotoxicity mechanisms and biodistribution of diamond nanoparticles on the skin cancer in C57 mouse.

The cytotoxicity of diamond nanoparticles (DNs) to various cell lines has been on focus by numerous scientists. The cellular toxicity system of DNs has not been fully understood or explained in skin cancer, at this point. This research was carried out to discover and reveal the potential impacts of DNs on the secluded brain, heart, liver, kidney, and skin in addition to evaluation of their cytotoxicity mechanism under test conditions. Their biological activities, for example cell viability, the level of reactive oxygen species (ROS), lipid peroxidation, cytochrome c release and Apoptosis/Necrosis were evaluated. Additionally, the bio-distribution of these nanomaterials in tissues was examined in the C57 mouse. Relying on the findings of the investigation, DNs were found to increase the ROS level, Malondialdehyde (MDA) content, release of cytochrome c, and cell death in skin significantly compared to other groups. In the C57 mouse, DNs were observed to have accumulated in skin tissue more intensively than they did in other organs. The present study presents for the proof that DNs can completely induce cell death signaling in skin cancer without bringing about a high cytotoxicity in other tissues. Results suggest that DNs can be valuable in recognition of skin cancer.

Fluorination of Diamond Nanoparticles in Slow Neutron Reflectors Does Not Destroy Their Crystalline Cores and Clustering While Decreasing Neutron Losses.

If the wavelength of radiation and the size of inhomogeneities in the medium are approximately equal, the radiation might be intensively scattered in the medium and reflected from its surface. Such efficient nanomaterial reflectors are of great scientific and technological interest. In previous works, we demonstrated a significant improvement in the efficiency of reflection of slow neutrons from a powder of diamond nanoparticles by replacing hydrogen located on the surface of nanoparticles with fluorine and removing the residual sp2 amorphous shells of nanoparticles via the fluorination process. In this paper, we study the mechanism of this improvement using a set of complementary experimental techniques. To analyze the data on a small-angle scattering of neutrons and X-rays in powders of diamond nanoparticles, we have developed a model of discrete-size diamond nanospheres. Our results show that fluorination does not destroy either the crystalline cores of nanoparticles or their clustering in the scale range of 0.6-200 nm. This observation implies that it does not significantly affect the neutron scattering properties of the powder. We conclude that the overall increase in reflectivity from the fluorinated nanodiamond powder is primarily due to the large reduction of neutron losses in the powder caused by the removal of hydrogen contaminations.

Evaluation of oxidative stress: Nanoparticle-based electrochemical sensors for hydrogen peroxide determination in human semen samples.

We have developed electrochemical sensors for the determination of H2O2 in a complex matrix such as human semen as a method to evaluate oxidative stress related to male infertility. Our sensors are based on the modification of conventional electrode surfaces with nanoparticles. We used diamond nanoparticles (DNp) either on glassy carbon or gold surfaces (GC/DNp and Au/DNp sensors, respectively), and copper nanoparticles electrochemically generated directly on glassy carbon surfaces (GC/CuNp). The morphology of the modified electrode surfaces was characterized by Atomic Force Microscopy (AFM), and the H2O2 determination performance evaluated by chronoamperometric measurements at different applied potentials. The best results are obtained for GC/DNp at +1.0 V, Au/DNp at -0.6 V and GC/CuNp at +0.2 V with detection limits (LD) of 1.1 µM, 2.4 µM and 2.6 µM, respectively. The analysis of H2O2 in doped synthetic semen using the GC/CuNp sensor shows the best recoveries, reaching a mean value of 103%. The GC/CuNp sensor was successfully applied to H2O2 analysis in real human semen. In this case, a H2O2 concentration of 1.42 ± 0.05 mM is found and recoveries of 102% on average are obtained.