Nanodiamonds (ND) possess unique properties, including high biocompatibility, tunable surface chemistry, and stable photoluminescence, that make them highly attractive for biomedical applications. In this study, we synthesized gold-coated nanodiamonds (NDAu) using a green chemistry route based on Nymphaea alba root extract as a natural reducing agent. The hybrids were produced from two types of ND with median diameters of 50 nm and 230 nm, which were subjected to different thermal treatments prior to the gold coating to modulate their surface properties. The functionalized particles were comprehensively characterized using a combination of spectroscopic techniques (UV-Vis spectroscopy, ATR-FTIR spectroscopy, Raman spectroscopy, PIXE), Powder X-ray Diffraction (PXRD), electron microscopy (SEM and TEM), and zeta potential. These techniques evidenced the impact of the thermal treatments on the NDs, reported the influence of the plant extracts on the final nanoparticles, as well as confirmed and quantified the presence of metallic gold in this material. Moreover, we carried out biological evaluation on A549 lung cell line to assess their cytotoxicity, cellular uptake, and impact on cell survival. Our results confirmed the efficacy of the gold-coating method, elucidating the modifications in particles structural, physical and chemical properties due to functionalization, and the interaction with cells. These nanoparticles could then be used for various biomedical applications, such as drug delivery or as potential radiosensitizers.

In this work, we investigate how hydrogenated nanodiamonds (NDs) influence the radiolytic formation of hydrogen peroxide (H2O2) and OH radicals (center dot OH) under X-rays to understand their potential roles as radio-sensitizer. To do so, changes in yields of H2O2and center dot OH in the presence of hydrogenated nanodiamonds (NDs) under X-rays are explored. Yields of H2O2are quantified by Ghomley technique. Yields of H2O2increase with the concentration of NDs under both oxygenated and de-oxygenated conditions. This enhancement is attributed to the structured adsorbed water layer at the ND surface, which alters secondary radical recombination pathways and promotes H2O2formation. Additionally, yields of center dot OH are evaluated using Amplex Red solution. Yields of center dot OH do not vary in the presence of NDs. This finding indicates that NDs do not decompose H2O2, the dominant route to additional center dot OH generation in nanoparticle-enhanced systems. Overall, while NDs do not amplify indirect action via center dot OH, their modulation of H2O2yields would still influence downstream oxidative processes and warrants further biological investigation.

This work presents a comprehensive comparative study of different methods to induce graphitization in diamond, with a focus on their impact on the material properties and potential applications. The employed graphitization methods vary between laser writing-based strategies using Bessel beams and irradiation-based methods incorporating keV broad beam implantation, focused Gallium ion beam lithography, and a thermal-based graphitization method. The study emphasizes the effects of annealing time in the thermal method and the influence of the induced graphite on the material electrical properties for all the employed methods. A key highlight of this work is the exploration of easy and innovative approaches to create 3D conductive patterns within diamonds. This is achieved through combining laser-based and ion beam methods, as well as optimizing ion beam parameters to enable the creation of 3D conductive patterns. Each method presents unique advantages: thermal annealing enables simple surface graphitization, ion implantation allows precise depth control for sub-surface structures, and Bessel beam laser writing facilitates direct 3D in-bulk modification without mechanical movement or masking. This comparative insight helps to identify the most suitable technique depending on the required electrode geometry and device integration constraints. The outcomes of each graphitization approach showcase unique benefits and limitations, giving various possibilities to employ diamonds in electrical applications. By building on prior research, this study offers an extended perspective on integrating advanced fabrication techniques to expand the use of diamonds in emerging technologies.

In recent decades, nanodiamonds (NDs) have emerged as innovative nanotools for weak magnetic fields and small temperature variation sensing, especially in biological systems. At the basis of the use of NDs as quantum sensors are nitrogen-vacancy center lattice defects, whose electronic structures are influenced by the surrounding environment and can be probed by the optically detected magnetic resonance technique. Ideally, limiting the NDs' size as much as possible is important to ensure higher biocompatibility and provide higher spatial resolution. However, size reduction typically worsens the NDs' sensing properties. This study endeavors to obtain sub-100 nm NDs suitable to be used as quantum sensors. Thermal processing and surface oxidations were performed to purify NDs and control their surface chemistry and size. Ion irradiation techniques were also employed to increase the concentration of the nitrogen-vacancy centers. The impact of these processes was explored in terms of surface chemistry (diffuse reflectance infrared Fourier transform spectroscopy), structural and optical properties (Raman and photoluminescence spectroscopy), dimension variation (atomic force microscopy measurements), and optically detected magnetic resonance temperature sensitivity. Our results demonstrate how surface optimization and defect density enhancement can reduce the detrimental impact of size reduction, opening to the possibility of minimally invasive high-performance sensing of physical quantities in biological environments with nanoscale spatial resolution.

We present a novel approach for the optical activation of the negatively-charged silicon vacancy ( VSi−) center in ion irradiated silicon carbide (SiC) via ns-pulsed laser annealing in the 234–2180 mJ cm− 2 energy density range. The laser annealing process is investigated under 355 nm and 532 nm wavelengths at pulse energy densities below the melting threshold and validated by means of Raman spectroscopy and photoluminescence mapping. The combined effect of ns pulsed laser annealing and subsequent thermal treatment is also assessed. The results offer a promising resource for the development of integrated photonic SiC devices and could be extended to a potentially wide range of applications involving other classes of solid-state quantum emitters.

The existing synthetic protocols for the direct functionalization of carbon-based nanomaterials often entail limitations due to their harsh reaction conditions, which require the use of high temperatures for extended periods. This study aims to overcome these limitations by developing mild and efficient synthetic protocols around 1,3-dipolar cycloaddition. Beginning with the well-established azomethine ylide derivatization, we progress to the utilization of nitrile oxide, and of nitrone derivatives for the functionalization of reduced graphene oxide (rGO) as well as of nanodiamonds (NDs). This comparative work employs both classical heating and microwave activation with the aim of reducing reaction times and enhancing efficacy. Results demonstrate that nitrone can react at 60 °C and that the reaction temperature may be decreased to 30 °C with nitrile oxide. Excellent progress was made in reducing the large excess of dipoles typically required for derivatization. Nitrile oxide was proved to be the most efficient in terms of derivatization degree, while nitrone was the most versatile reagent, facilitating the decoration of the carbon nanolayer with disubstituted dihydroisoxazole. To accurately assess the degree of functionalization, the reaction products underwent characterization using various spectroscopic and analytical techniques. Additionally, an indirect evaluation of the reaction outcome was conducted through Fmoc deprotection and quantification.

Novel approach for the functionalization of nanodiamonds with Hyaluronic Acid is proposed, utilizing non-covalent anchoring. NDs exhibit improved properties including increased internalization in human adenocarcinoma cells overexpressing CD44 receptor.

Sensing based on Nitrogen-Vacancy (NV) centers in nanodiamonds (NDs) offers significant potential across various applications. However, optimizing their quantum-optical properties remains challenging. This study focuses on enhancing and controlling the optical properties of NV centers in NDs through surface chemistry tuning and proton beam irradiation. Systematic thermal oxidations were performed to investigate the evolution of surface chemical groups using IR spectroscopy and their influence on optical properties using photoluminescence spectroscopy and PL decay measurements. Proton irradiation was explored over a wide range of fluences (10^14 to 10^17 cm^-2) to precisely control the NV center concentration, identifying conditions that maximize creation and emission intensity. Furthermore, NV center charge state control was achieved by analyzing the NV-/NV0 ratio with varying surface terminations and NV center concentrations. A novel predictive mathematical model was developed to evaluate the efficiencies of forming NV- and NV0. Although tested specifically with proton-irradiated NDs, this model has broad applicability, representing a significant advancement in predicting the outcomes of ion-beam-based color center generation in diamond.

Droplet-based microfluidics systems have become widely used in recent years thanks to their advantages, varying from the possibility of handling small fluid volumes to directly synthesizing and encapsulating various living forms for biological-related applications. The effectiveness of such systems mainly depends on the ability to control some of these systems' parameters, such as produced droplet size and formation time, which represents a challenging task. This work reports an experimental study on tuning droplet size and generation time in a flow-focusing geometry fabricated with stereolithography 3D printing by exploring the interplay of phase and geometrical parameters. We produced droplets at different low flow rates of continuous and dispersed phases to assess the effect of each of these phases on the droplets' size and formation time. We observed that smaller droplets were produced for high viscosity oil and water phase, along with high flow rates. In addition, changing the microfluidics channels' width, and morphology of the orifice has shown a similar effect on droplet size, as shown in the case of high-viscosity solutions. The variation of the bifurcation angle shows a noticeable variation in terms of the achieved droplet size and formation time. We further investigated the impact of modifying the width ratio of the continuous and dispersed phases on droplet formation.

Nanoparticles are being increasingly studied to enhance radiation effects. Among them, nanodiamonds (NDs) are taken into great consideration due to their low toxicity, inertness, chemical stability, and the possibility of surface functionalization. The objective of this study is to explore the influence of the chemical/physical properties of NDs on cellular radiosensitivity to combined treatments with radiation beams of different energies. DAOY, a human radioresistant medulloblastoma cell line was treated with NDs—differing for surface modifications [hydrogenated (H-NDs) and oxidized (OX-NDs)], size, and concentration—and analysed for (i) ND internalization and intracellular localization, (ii) clonogenic survival after combined treatment with different radiation beam energies and (iii) DNA damage and apoptosis, to explore the nature of ND–radiation biological interactions. Results show that chemical/physical characteristics of NDs are crucial in determining cell toxicity, with hydrogenated NDs (H-NDs) decreasing either cellular viability when administered alone, or cell survival when combined with radiation, depending on ND size and concentration, while OX-NDs do not. Also, irradiation at high energy (γ-rays at 1.25 MeV), in combination with H-NDs, is more efficient in eliciting radiosensitisation when compared to irradiation at lower energy (X-rays at 250 kVp). Finally, the molecular mechanisms of ND radiosensitisation was addressed, demonstrating that cell killing is mediated by the induction of Caspase-3-dependent apoptosis that is independent to DNA damage. Identifying the optimal combination of ND characteristics and radiation energy has the potential to offer a promising therapeutic strategy for tackling radioresistant cancers using H-NDs in conjunction with high-energy radiation.

MicroGraphited-Diamond-Multi Electrode Arrays (μG-D-MEAs) can be successfully used to reveal, in real time, quantal exocytotic events occurring from many individual neurosecretory cells and/or from many neurons within a network. As μG-D-MEAs arrays are patterned with up to 16 sensing microelectrodes, each of them recording large amounts of data revealing the exocytotic activity, the aim of this work was to support an adequate analysis code to speed up the signal detection. The cutting-edge technology of microGraphited-Diamond-Multi Electrode Arrays (μG-D-MEAs) has been implemented with an automated analysis code (APE, Amperometric Peak Analysis) developed using Matlab R2022a software to provide easy and accurate detection of amperometric spike parameters, including the analysis of the pre-spike foot that sometimes precedes the complete fusion pore dilatation. Data have been acquired from cultured PC12 cells, either collecting events during spontaneous exocytosis or after L-DOPA incubation. Validation of the APE code was performed by comparing the acquired spike parameters with those obtained using Quanta Analysis (Igor macro) by Mosharov et al.

Nanodiamonds (NDs) gained increasing attention in multiple research areas due to the possibility of tuning their physical and chemical features by functionalizing their surface. This has a crucial impact on their electrical properties, which are essential in applications such as the development of innovative sensors and in the biomedical field. The great interest in electrical conduction in NDs has driven the scientific community to its extensive investigation. The role of various functionalities has been considered and different conduction mechanisms have been proposed. In this work, we reported on a systematic study of the modification of the electrical properties of differently sized NDs, as a function of different thermal treatments in air, hydrogen or inert atmosphere. Samples were electrically characterized in controlled humidity conditions to consider the influence of water on conductivity. NDs electrical properties were interpreted in connection with their surface chemistry and structural features, probed with infrared and Raman spectroscopies. The presence of surface graphite, hydrogen terminations or water adsorbed on hydrophilic oxygen-containing functional groups rendered NDs more conductive. These moieties indeed enabled different conduction mechanisms, which were respectively graphite-mediated conduction, water-induced transfer doping and Grotthus mechanism in surface-adsorbed water. The effect of particles size on conductivity has also been evaluated and discussed. Our experimental findings shed light on the link between surface modifications and electrical properties of NDs, providing at the same time an interpretative key to understanding the effect of particles dimensions.

In recent decades, nanodiamonds (NDs) have earned increasing interest in a wide variety of research fields, thanks to their excellent mechanical, chemical, and optical properties, together with the possibility of easily tuning their surface chemistry for the desired purpose. According to the application context, it is essential to acquire an extensive understanding of their interaction with water in terms of hydrophilicity, environmental adsorption, stability in solution, and impact on electrical properties. In this paper, we report on a systematic study of the effects of reducing and oxidizing thermal processes on ND surface water adsorption. Both detonation and milled NDs were analyzed by combining different techniques. Temperature-dependent infrared spectroscopy was employed to study ND surface chemistry and water adsorption, while dynamic light scattering allowed the evaluation of their behavior in solution. The influence of water adsorption on their electrical properties was also investigated and correlated with structural and optical information obtained via Raman/photoluminescence spectroscopy. In general, higher oxygen-containing surfaces exhibited higher hydrophilicity, better stability in solution, and higher electrical conduction, although for the latter the surface graphitic contribution was also crucial. Our results provide in-depth information on the hydrophilicity of NDs in relation to their surface chemical and physical properties, by also evaluating the impacts on their aggregation and electrical conductance.