Publications

In this study, we report the performance improvement of wound dressings by covering them with magnetite-based nanostructured coatings. The magnetite nanoparticles (Fe3O4 NPs) were functionalized with Nigella sativa (N. sativa) powder/essential oil and dicloxacillin and were synthesized as coatings by matrix assisted pulsed laser evaporation (MAPLE). The expected effects of this combination of materials are: (i) to reduce microbial contamination, and (ii) to promote rapid wound healing. The crystalline nature of core/shell Fe3O4 NPs and coatings was determined by X-ray diffraction (XRD). Differential Scanning Calorimetry (DSC) and Thermo Gravimetric Analysis (TGA) have been coupled to investigate the stability and thermal degradation of core/shell nanoparticle components. The coatings' morphology was examined by scanning electron microscopy (SEM). The distribution of chemical elements and functional groups in the resulting coatings was evidenced by Fourier transform infrared (FTIR) spectrometry. In order to simulate the interaction between wound dressings and epithelial tissues and to evaluate the drug release in time, the samples were immersed in simulated body fluid (SBF) and investigated after different durations of time. The antimicrobial effect was evaluated in planktonic (free-floating) and attached (biofilms) bacteria models. The biocompatibility and regenerative properties of the nanostructured coatings were evaluated in vitro, at cellular, biochemical, and the molecular level. The obtained results show that magnetite-based nanostructured coatings functionalized with N. sativa and dicloxacillin are biocompatible and show an enhanced antimicrobial effect against Gram positive and Gram negative opportunistic bacteria.

Due to the great significance of amino acids, a substantial number of research studies has been directed toward the development of effective and reliable platforms for their evaluation, detection, and identification. In order to support these studies, a new electrochemical platform based on PANI/ZnO nanowires' modified carbon inks screen-printed electrodes was developed for qualitative analysis of electroactive amino acids, with emphasis on tyrosine (Tyr) and tryptophan (Trp). A comparative investigation of the carbon ink before and after modification with the PANI/ZnO was performed by scanning electron microscopy and by Raman spectroscopy, confirming the presence of PANI and ZnO nanowires. Electrochemical investigations by cyclic voltammetry and electrochemical impedance spectroscopy have shown a higher charge-transfer rate constant, which is reflected into lower charge-transfer resistance and higher capacitance values for the PANI/ZnO modified ink when compared to the simple carbon screen-printed electrode. In order to demonstrate the electrochemical performances of the PANI/ZnO nanowires' modified carbon inks screen-printed electrodes for amino acids analysis, differential pulse voltammograms were obtained in individual and mixed solutions of electroactive amino acids. It has been shown that the PANI/ZnO nanowires' modified carbon inks screen-printed electrodes allowed for tyrosine and tryptophan a peak separation of more than 100 mV, enabling their screening and identification in mixed solutions, which is essential for the electrochemical analysis of proteins within the proteomics research field.

Drinking water contamination has become a worldwide problem due to the highly negative effects that pollutants can have on human organisms and the environment. Hydroxyapatite (HAp) has the appropriate properties for the immobilization of various pollutants, being considered amongst the most cost-effective materials for water decontamination. The main objective of this study was to use synthesized hydroxyapatite for the elimination of Sr2+ ions from contaminated solutions. The hydroxyapatite used in the decontamination process was synthesized in the laboratory using an adapted method. The hydroxyapatite powder (HAp) resulting from the synthesis was analyzed both before and after the elimination of Sr2+ ions from contaminated solutions. The efficiency of the HAp nanoparticles in removing Sr2+ ions from contaminated solution was determined by batch adsorption experiments. X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) were used to study the HAp samples before and after the removal of Sr2+ ions. The ability of HAp nanoparticles to eliminate strontium ions from contaminated solutions was established. Moreover, the removal of Sr2+ ions from the contaminated aqueous solutions was highlighted by ultrasound measurements. The value of the stability parameter calculated by ultrasonic measurements after the removal of Sr2+ ions from the contaminated solution was similar to that of double distilled water whose stability was used as reference. The outcomes of the batch experiments and the parameters obtained from Langmuir and Freundlich models indicated that the HAp nanoparticles had a strong affinity for the elimination of Sr2+ ions from polluted solutions. These results emphasized that HAp nanoparticles could be excellent candidates in the development of new technologies for water remediation. More than that, the outcomes of the cytotoxic assays proved that HAp nanoparticles did not induce any noticeable harmful effects against HeLa cells and did not affect their proliferation after 1 day and 7 days of incubation.

Accelerator Mass Spectrometry (AMS) and cosmogenic nuclides techniques are used in quantitative geomorphological studies on large time scale. In order to accurately date surface exposure to cosmic rays, the amount of pure quartz taken into account, needs to be well determined. Depending on the particularity of the rocks, sometimes the presence of feldspar in geological samples hinders the accurate determination of 26Al and 10Be by AMS. To overcome this problem, our paper proposes the assessment of quartz purity by SEM-EDX analysis, in an objective and facile way, compared to ICP-MS method. The proposed methodology is not only effective, but it shows features that save time and excessive consumption of reagents that often are not environment and health friendly.

A numerical algorithm for interface analysis of wicking drops was developed. The code identifies the interface points and subsequently calculates the diameter, volume and contact angle of the drop. As the code can work with multiple frames, it can evaluate the evolution in time of these parameters and calculate the spreading velocity and the flow rate. The performance of the code was tested with solutions of poly(ethylene oxide) of 0.5% and 5% (w/v) concentration. The mean execution time was 0.5 seconds per frame. Therefore, the code can greatly improve the analysis of fluids wicking in porous media, where numerous frames are involved.

The purpose of the work is the synthesis and characterization of TiO2 nanoparticles. These were obtained by two different methods, precipitation and sol-gel, starting from titanium(IV) isopropoxide and calcining at 500 degrees C for 2 h. The compositional, structural, morphological and optical properties of the resulting powders were investigated by energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, Raman spectroscopy, scanning electron microscopy, reflectance spectroscopy and photoluminescence spectroscopy. The thermally treated samples contain TiO2 as single phase with tetragonal structure, known as anatase. SEM analysis showed quasi-spherical particles with a diameter of few nanometres for the calcined samples, while the optical studies revealed band gap values of 3.04 and 3.17 eV, as a function of the preparation route.

Cu2SnS3 thin films emerged as promising materials for sustainable photovoltaics due to their earth-abundant constituents and great optoelectronic properties. The formation of secondary phases during synthesis poses challenges to achieving efficient performances. This study investigates the impact of secondary on the of CTS films.

In this study, we evaluate the feasibility of using quantum neural networks for classifying gravitational waveforms, using both simulators and quantum computers. The analysis is quite interdisciplinary in its nature, combining knowledge involving astrophysics, quantum information as well as quantum and classical machine learning. We showed that the quantum classifiers and hybrid classical-quantum layers give highly accurate results when tested on a simple dataset and ran on a simulator; also, adding a quantum layer to poorly performing classical neural network can highly improve its accuracy. When running on a real quantum computer, error minimizing algorithms need to be implemented in order to obtain a satisfying accuracy.

Proteins are vital components of living cells and the loss of their native functions has been associated with a wide variety of medical conditions. From this point of view, investigation of the protein microenvironment is crucial to support the development of therapeutic approaches capable of ensuring cellular functions. Therefore, analytical assays for the detection, quantification, and characterization of proteins, drugs, and protein-drug complexes play an essential role in fundamental research and clinical applications. Electrochemistry arises as an alternative methodology for fast assessment of proteins and drugs and is attractive due to the adaptability to miniaturization and scalability of electroanalytical devices, which then can be further employed as strategies towards personalized medical care. Thus, this review summarizes electrochemical investigations in the past 10 years on protein-based analytical devices and biosensors. A general overview of electrochemical assays that integrate proteins with nanostructured materials and conductive polymers is presented. Applications of electrochemical assays and biosensors were divided into four categories. First, those designed for drug screening strategies that focus on targeting specific intracellular, extracellular, or membrane protein subdomains to modulate their functions, aggregation/misfolding of proteins, and protein degradation pathways. Then, drug metabolism assays that involve mimicking natural metabolic pathways to identify potential safety and efficacy issues related to a drug or its metabolites. The third was dedicated to electrochemical drug delivery systems with anchored drugs in the form of bioconjugates, while the fourth was dedicated to electroanalytical methodologies for quantitative drug assays, where the electroactivity of the target species is often used to correlate the electrochemical signal to their concentration.

In this study, we characterized the temperature-dependent electrical conductivity properties of undoped and lightly doped bulk InSb samples using terahertz time-domain spectroscopy. We obtained the permittivity spectra at low temperatures and analyzed the carrier density and mobility by fitting the spectra to the Drude model. Based on our analysis, we show the temperature dependence of the optical constants and explain the underlying physical mechanisms for the observed behavior. Our results provide important insights into the electronic properties of InSb.