Cristian Pirvu

Copper has become more important owing to its eco-friendliness and persistent efficacy against infections. Furthermore, copper has benefits such as safety in use and durability. This study aimed to develop and assess the antibacterial efficacy of stainless steel coated with a composite layer, which is nanostructured and incorporates copper, to create antibacterial surfaces with good adherence and good corrosion resistance. The composite coating was produced using anodic oxidation, with an external copper layer applied via pulse electroplating. The homogenous cauliflower-like covering showed important characteristics, like increased surface roughness, boosted surface free energy, reduced contact angle, and higher hardness. Additionally, the adherence between the composite covering and the substrate was exceptional. Electrochemical experiments indicated aggressive corrosion behavior in chloride-containing settings. Antibacterial tests were conducted on four prevalent bacterial strains: Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Salmonella typhimurium—microorganisms often linked to healthcare and environmental pollution. The coating exhibited enhanced antibacterial efficacy relative to untreated steel and anodized steel. Results indicated that the composite coating is an effective and possibly cost-efficient method for controlling the surface proliferation of the mentioned pathogens.

This study investigates the antibacterial performance of Ti50Zr alloys modified by anodization and ZnO coating, emphasizing the complex interplay of surface properties that influence bacterial inhibition. Three surface morphologies were created via anodization: compact oxide (CO), nanotube (NT), and nanochannels (NC). The antibacterial activity of the modified surfaces was evaluated against Escherichia coli using inhibition rates and bactericidal ratios. The results showed that surface roughness and morphology significantly affected antibacterial efficiency, with the Ti50Zr NC structure exhibiting the highest inhibition rate (60%). ZnO coating further enhanced antibacterial activity, particularly with Ti50Zr NCZnO, which showed the best performance (75% inhibition). Additionally, Ti50Zr NTZnO demonstrated a significant improvement in antibacterial efficiency, with ZnO nanoparticles (10 nm) playing a key role in membrane penetration. The study also examined the impact of surface energy, wettability, and electrochemical properties on bacterial adhesion and killing mechanisms. These findings underscore the critical influence of surface nanostructuring, ZnO nanoparticle size, and coating on enhancing the antibacterial properties of Ti50Zr, highlighting the complexity of surface interactions in optimizing biomaterials for medical applications.

TiO₂ nanotubes and self-reduced TiO₂ nanotube semiconductor electrodes were used for electrochemical metal ion detection in an open circuit under photo-accumulation conditions. Due to their surface properties, the electrodes showed different responses towards metal ions at different wavelengths of light radiation. Using TiO₂ nanotube-based electrodes, Pb(II) and Cu(II) ions were detected at irradiation wavelengths of 389 nm and 426 nm. Detection limits of 8 × 10⁻⁹ M and 5 × 10⁻⁹ M for Pb(II) and 3 × 10⁻⁸ and 7 × 10⁻⁹ M for Cu(II) were obtained at the two wavelengths, respectively. The self-reducing electrode showed a response to Pb(II) and Cu(II) ions when irradiated with light at 389 nm, while at 426 nm, Hg(II) ions along with Pb(II) and Cu(II) ions were detected. The obtained detection limits with self-reduced TiO₂ nanotube electrodes for Pb(II) and Cu(II) at 389 nm were 2 × 10⁻⁷ M and 8 × 10⁻⁹ M, respectively. At a wavelength of 426 nm, the detection limits were 1 × 10⁻⁷ M, 3 × 10⁻⁹, and 4 × 10⁻⁹ M for Pb(II), Cu(II), and Hg(II), respectively.

Estrogens, widely used for therapeutic or contraceptive purposes, act as endocrine disruptors in aquatic systems and have adverse effects on a wide range of living organisms. Wastewater insufficiently treated by conventional methods is the main way for estrogens to enter aquatic systems. Therefore, the purpose of this paper is to develop a novel photocatalytic system for the removal of the estrogenic mixture estradiol valerate/norgestrel from wastewater. The photocatalytic modules are operated in a plug flow reactor system under a UV-A radiation field, and the photocatalyst (TiO₂, ZnO or TiO₂/ZnO) is immobilized on an inert support of glass balls that are strung on stainless-steel wire and arranged in rows along the photocatalytic modules. The photocatalysts were synthesized by the sol–gel method and then deposited on the inert glass support by the hot method, after which it was calcined for two hours at a temperature of 500 °C. The experimental results showed that the efficiency of photocatalytic degradation largely depends on the dose of photocatalyst. The dose of photocatalyst can be adjusted by adding or removing photocatalytic modules, each of which have an approximately equal amount of photocatalyst. The best result was obtained for the TiO₂/ZnO photocatalyst, the organic substrate being practically mineralized in 120 min, for which only two photocatalytic modules are needed.

The current research aims to elucidate the influence of reduction process of TiO₂ nanostructures on the surface properties of a bioinspired Ti modified implant, considering that the interface between a biomaterial surface and the living tissue plays an important role for this interaction. The production of reduced TiO₂ nanotubes (RNT) with lower band gap is optimized and their performance is compared with those of simple TiO₂ nanotubes (NT). The more conductive surfaces provided by the presence of RNT on Ti, allow a facile deposition of silk fibroin (SF) film using the electrochemical deposition method. This hybrid film is then functionalized with ZnO nanoparticles, to improve the antibacterial effect of the coating. The modified Ti surface is evaluated in terms of surface chemistry, morphology and roughness, wettability, surface energy, surface charge and antibacterial properties. Surface analysis such as SEM, AFM, FTIR and contact angle measurements were performed to obtain topographical features and wettability. FT‐IR analysis confirms that SF was effectively attached to TiO₂ nanotubes surfaces. The electrochemical deposition of SF and SF‐ZnO reduced the interior diameter of nanotubes from ~85 nm to approx. 50–60 nm. All modified surfaces have a hydrophilic character.

Inspired by natural photosynthesis, a new green catalyst with better photocatalytic properties was obtained. Nanostructured TiO₂, a cheap cost natural Chlorophyll‐a as an electron promotor and a mussel‐inspired polydopamine (PD) bio adhesive were synergistically combined in the double S‐scheme hybrid photocatalysts The role of PD as a bridging molecule between the pigments of Chl and TiO₂ was clearly demonstrated by improved charge transfer and recombination rate. Methylorange as a probe molecule was used to test the stability and efficiency of the new photocatalyst. This challenging approach on obtaining new green bioinspired catalysts avoiding critical raw materials is in line with the new vision on catalysts. The results of this study show the effectiveness and stability of the new photocatalyst. Based on the combined effect of PD functionalization and Chl sensitization, the NT/PD‐Chl heterostructure photocatalyst had the best photo(electro)catalytic performance for MO degradation which was shown to be 97.74 % after 180 min.

Antibiotics are a novel class of contaminants that represent a substantial risk to human health, making their detection an important task. In this study, ZnO nanostructures were prepared starting from Bombyx mori silk fibroin and Zn(NO₃)₂, using thermal treatment. The resulting ZnO structures were characterized using SEM, FT-IR, and XRD. They had a fibrous morphology with a wurtzite crystalline structure, with nanometric dimensions. FT-IR and XRD confirmed silk fibroin’s disappearance after thermal treatment. To prepare modified electrodes for amoxicillin (AMX) antibiotic detection, ZnO nanostructures were mixed with Nafion polymer and drop-casted on an electrode’s surface. Parameters such as drying time and concentration appeared to be important for electrochemical detection. Differential pulse voltammetry (DPV) was sensitive for AMX detection. The measurements revealed that the novel electrode based on ZnO nanostructures embedded in Nafion polymer has potential to be used for AMX electrochemical detection.

Due to their superior mechanical and chemical properties, titanium (Ti) and its alloys have been widely used as orthopedic implantable devices. However, their bioinertness represents a limitation, which can be overcome by employing various surface modifications, such as TiO₂ nanotube (TNT) fabrication via electrochemical anodization. Anodic TNTs present tunable dimensions and unique structures, turning them into feasible drug delivery platforms. In the present work, TNTs were loaded with icariin (Ica) through an adhesive intermediate layer of polydopamine (DP), and their in vitro and in vivo biological performance was evaluated. The successful fabrication of the modified surfaces was verified by scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), and contact angle measurements (CA), while the in vitro release of Ica was evaluated via UV-VIS spectrophotometry. In terms of in vitro behaviour, comparative studies on RAW 264.7 macrophages demonstrated that the TNT substrates, especially TNT-DP-Ica, elicited a lower inflammatory response compared to the Ti support. Moreover, the in vivo implantation studies evinced generation of a reduced fibrotic capsule around this implant and increased thickness of the newly formed bone tissue at 1 month and 3 months post-implantation, respectively. Overall, our results indicate that the controlled release of Ica from TNT surfaces could result in an improved osseointegration process.

This research deals with the deposition of copper on a steel substrate. Two different methods were investigated: electrochemical and magnetron sputtering. The deposition parameters were optimized to obtain a coating layer with uniform granular structure and good adhesion to the substrate. As a novelty, carbon nanowalls (CNW) were used as reinforcement in copper coatings on the steel surface. The morphology of the coatings, adhesion and Vickers microhardness were performed to emphasize the CNW influence on the coating properties. Open circuit potential and Tafel analysis were used for electrochemical characterization. These kinds of CNW-copper composite with improved hardness and adhesion and surface electrical resistance around 1 Ω·cm could have miscellaneous applications in different domains such as aerospace, electronics, automotive and power-generation.