Vladimir Lucian Ene

This study aimed to compare the surface morphology and antimicrobial/antibiofilm behavior of three semi-permanent cements used in implantology: FOZ (zinc oxide-based), DT (resin-based), and CIS (glass ionomer), after aging in air and artificial saliva, and after exposure to clinically relevant oral microbial strains. Surface morphology and elemental composition were analyzed by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS), and antimicrobial and antibiofilm activity was quantified by determining the number of colony-forming units (CFU/mL) for Gram-positive bacteria (Staphylococcus aureus, Enterococcus faecalis), Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa), and fungi (Candida albicans, C. parapsilosis). FOZ exhibited a very rough surface rich in zinc, associated with the most pronounced reduction in microbial adhesion; CIS showed a relatively compact ionomer matrix with barium-rich domains and good antibiofilm activity, particularly against P. aeruginosa, while DT exhibited a predominantly organic, smooth surface with isolated inorganic aggregates and a more pronounced inhibition profile against E. coli. The results indicate that the microstructure and surface chemical composition of the cements directly influence the pattern of microbial colonization and antibiofilm efficacy, providing a rationale for selecting the cementing material based on microbiological risk and specific clinical conditions.

This study aimed to compare the surface morphology and antimicrobial/antibiofilm behavior of three semi-permanent cements used in implantology: FOZ (zinc oxide-based), DT (resin-based), and CIS (glass ionomer), after aging in air and artificial saliva, and after exposure to clinically relevant oral microbial strains. Surface morphology and elemental composition were analyzed by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS), and antimicrobial and antibiofilm activity was quantified by determining the number of colony-forming units (CFU∕mL) for Gram-positive bacteria (Staphylococcus aureus, Enterococcus faecalis), Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa), and fungi (Candida albicans, C. parapsilosis). FOZ exhibited a very rough surface rich in zinc, associated with the most pronounced reduction in microbial adhesion; CIS showed a relatively compact ionomer matrix with barium-rich domains and good antibiofilm activity, particularly against P. aeruginosa, while DT exhibited a predominantly organic, smooth surface with isolated inorganic aggregates and a more pronounced inhibition profile against E. coli. The results indicate that the microstructure and surface chemical composition of the cements directly influence the pattern of microbial colonization and antibiofilm efficacy, providing a rationale for selecting the cementing material based on microbiological risk and specific clinical conditions.

In recent years, significant advancements in nanotechnology have facilitated the synthesis of zinc oxide (ZnO) nanoparticles with tailored sizes and shapes, offering versatile applications across various fields, particularly in biomedicine. ZnO’s multifunctional properties, such as semiconductor behavior, luminescence, photocatalytic activity, and antibacterial efficacy, make it highly attractive for biomedical applications. This study focuses on synthesizing ZnO nanoparticles via the microwave-assisted hydrothermal method, varying the precursor concentrations (0.3488 mol/L, 0.1744 mol/L, 0.0872 mol/L, 0.0436 mol/L, and 0.0218 mol/L) and reaction times (15, 30, and 60 min). Characterization techniques, including X-ray diffraction, scanning electron microscopy, transmission electron microscopy, BET surface area analysis, and Fourier transform infrared spectroscopy were employed to assess the structural, morphological, and chemical properties. The predominant morphology is observed to be platelets, which exhibit a polygonal shape with beveled corners and occasionally include short rod-like inserts. The thickness of the platelets varies between 10 nm and 50 nm, increasing with the concentration of Zn²⁺ in the precursor solution. Preliminary antimicrobial studies indicated that all strains (S. aureus, E. coli, and C. albicans) were sensitive to interaction with ZnO, exhibiting inhibition zone diameters greater than 10 mm, particularly for samples with lower precursor concentrations. Cell viability studies on human osteoblast cells demonstrated good compatibility, affirming the potential biomedical applicability of synthesized ZnO nanoparticles. This research underscores the influence of synthesis parameters on the properties of ZnO nanoparticles, offering insights for optimizing their design for biomedical applications.

A challenge in tissue engineering and the pharmaceutical sector is the development of controlled local release of drugs that raise issues when systemic administration is applied. Strontium is an example of an effective anti-osteoporotic agent, used in treating osteoporosis due to both anti-resorptive and anabolic mechanisms of action. Designing bone scaffolds with a higher capability of promoting bone regeneration is a topical research subject. In this study, we developed composite multi-layer three-dimensional (3D) scaffolds for bone tissue engineering based on nano-hydroxyapatite (HA), Sr-containing nano-hydroxyapatite (SrHA), and poly-ε-caprolactone (PCL) through the material extrusion fabrication technique. Previously obtained HA and SrHA with various Sr content were used for the composite material. The chemical, morphological, and biocompatibility properties of the 3D-printed scaffolds obtained using HA/SrHA and PCL were investigated. The 3D composite scaffolds showed good cytocompatibility and osteogenic potential, which is specifically recommended in applications when faster mineralization is needed, such as osteoporosis treatment.

Fine-tuning of grain sizes can significantly influence the interaction between different dielectric phenomena, allowing the development of materials with tailored dielectric resistivity. By virtue of various synthesis mechanisms, a pathway to manipulate grain sizes and, consequently, tune the material’s dielectric response is revealed. Understanding these intricate relationships between granulation and dielectric properties can pave the way for designing and optimizing materials for specific applications where tailored dielectric responses are sought. The experimental part involved the fabrication of dense BCT-BZT ceramics with different grain sizes by varying the synthesis (conventional solid-state reaction route and sol-gel) and consolidation methods. Both consolidation methods produced well-crystallized specimens, with Ba_0.85Ca_0.15O₃Ti_0.9Zr_0.1 (BCTZ) perovskite as the major phase. Conventional sintering resulted in microstructured and submicron-structured BCT-BZT ceramics, with average grain sizes of 2.35 μm for the solid-state sample and 0.91 μm for the sol-gel synthesized ceramic. However, spark plasma sintering produced a nanocrystalline specimen with an average grain size of 67.5 nm. As the grain size decreases, there is a noticeable decrease in the maximum permittivity, a significant reduction in dielectric losses, and a shifting of the Curie temperature towards lower values.

Our concern was to obtain a biocomposite material with improved properties of the constituent materials (poly(lactic- co-glycolic acid) (PLGA) and zinc–boron (Zn–B) complex) in accordance with the novelties in the field of delivery systems for therapeutic agents which lately redefine the importance of biopolymer nanocomposites with PLGA (biodegradable composites). The advantages of such a biomaterial target the health system, being easy to obtain, through a cost-effective method. The water/oil/water double emulsion method also allows the adjustment of the synthesis parameters, to maximize the degree of Zn–B complex encapsulation. The morphological aspects of the samples (size, shape, porosity) were established by scanning electron microscopy (SEM). Particle size distribution (by volume and by number) was determined by direct light scattering (DLS). For all the synthesized materials, the observed morphology was typical for PLGA, spherical one. The particle size distribution showed that depending on the synthesis conditions, the particles can be obtained with diameters between 10–450 nm range and the value of the zeta potential (ZP) shows that the particles have electronegative surface charge, which offers a favorable perspective on the phenomena of aggregation, flocculation, dispersion. It was observed, applying the design of experiments (DoE), that the size of the particles increased with increasing amounts of PLGA and polyvinyl alcohol (PVA) in the formulation, while ZP increased with higher PLGA and smaller PVA. The encapsulation efficiency was determined by ultra-high performance liquid chromatography/mass spectrometry (UHPLC/MS).

Numerous studies have reported the possibility of enhancing the properties of materials by incorporating foreign elements within their crystal lattice. In this context, while magnetite has widely known properties that have been used for various biomedical applications, the introduction of other metals within its structure could prospectively enhance its effectiveness. Specifically, zinc and cerium have demonstrated their biomedical potential through significant antioxidant, anticancer, and antimicrobial features. Therefore, the aim of the present study was to develop a series of zinc and/or cerium-substituted magnetite nanoparticles that could further be used in the medical sector. The nanostructures were synthesized through the co-precipitation method and their morpho-structural characteristics were evaluated through X-ray diffraction (XRD), inductively coupled plasma mass spectrometry (ICP-MS), X-ray photoelectron spectroscopy (XPS), dynamic light scattering (DLS), zeta potential, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDX) analyses. Furthermore, the nanostructures were subjected to a ROS-Glo H₂O₂ assay for assessing their antioxidant potential, MTT assay for determining their anticancer effects, and antimicrobial testing against S. aureus, P. aeruginosa, and C. albicans strains. Results have proven promising for future biomedical applications, as the nanostructures inhibit oxidative stress in normal cells, with between two- and three-fold reduction and cell proliferation in tumor cells; a two-fold decrease in cell viability and microbial growth; an inhibition zone diameter of 4–6 mm and minimum inhibitory concentration (MIC) of 1–2 mg/mL.

The main objective of the study was to produce alternative binder materials, obtained with low cost, low energy consumption, and low CO₂ production, by regenerating end-of-life (EOL) materials from mineral deposits, to replace ordinary Portland cement (OPC). The materials analyzed were ash and slag from the Turceni thermal power plant deposit, Romania. These were initially examined for morphology, mineralogical composition, elemental composition, degree of crystallinity, and heating behavior, to determine their ability to be used as a potential source of supplementary cementitious materials (SCM) and to establish the activation and transformation temperature in the SCM. The in-situ pozzolanic behavior of commercial cement, as well as cement mixtures with different percentages of ash addition, were further observed. The mechanical resistance, water absorption, sorptivity capacity, resistance to alkali reactions (ASR), corrosion resistance, and resistance to reaction with sulfates were evaluated in this study using low-vacuum scanning electron microscopy.

In this work, we obtain mesoporous silica systems loaded with polyphenolic compounds (p-coumaric acid, trans-ferulic acid, epicatechin, and catechin). Polyphenolic compounds are used as biologically active agents for the treatment of various diseases. These compounds have high antioxidant activity. As a carrier, two types of mesoporous silica have been proposed and obtained according to the classical templating method with cetyltrimethylammonium bromide, CTAB, under alkaline conditions. Polyphenols (p-coumaric acid, trans-ferulic acid, epicatechin, and catechin) were loaded under vacuum into the mesoporous silica. The materials obtained were characterized by Scanning Electron Microscopy, X-ray Diffraction, the Brunauer–Emmett–Teller Method, Complex Thermal Analysis–DTA-TG and Fourier Transform Infrared Spectroscopy. In this study, mesoporous silica systems were obtained and further loaded with p-coumaric acid, trans-ferulic acid, epicatechin and catechin. The results highlight that the materials can be used as drug delivery systems, with the results being promising (simulated gastric fluid, SGF, and simulated intestinal fluid, SIF) for various environments. The proposed loading methodology is suitable for loading these natural agents, mostly, inside the pores.

Replacing the petroleum-based materials in the food industry is one of the main objectives of the scientists and decision makers worldwide. Biodegradable packaging will help diminish the environmental impact of human activity. Improving such biodegradable packaging materials by adding antimicrobial activity will not only extend the shelf life of foodstuff, but will also eliminate some health hazards associated with food borne diseases, and by diminishing the food spoilage will decrease the food waste. The objective of this research was to obtain innovative antibacterial films based on a biodegradable polymer, namely alginate. Films were characterized by environmental scanning electron microscopy (ESEM), Fourier-transform infrared spectroscopy (FTIR) and microscopy, complex thermal analysis (TG-DSC-FTIR), UV-Vis and fluorescence spectroscopy. Water vapor permeability and swelling behavior were also determined. As antimicrobial agents, we used silver spherical nanoparticles (Ag NPs) and lemongrass essential oil (LGO), which were found to act in a synergic way. The obtained films exhibited strong antibacterial activity against tested strains, two Gram-positive (Bacillus cereus and Staphylococcus aureus) and two Gram-negative (Escherichia coli and Salmonella Typhi). Best results were obtained against Bacillus cereus. The tests indicate that the antimicrobial films can be used as packaging, preserving the color, surface texture, and softness of cheese for 14 days. At the same time, the color of the films changed (darkened) as a function of temperature and light presence, a feature that can be used to monitor the storage conditions for sensitive food.