Electrochemical and Mechanical Properties of Hexagonal Titanium Dioxide Nanotubes Formed by Sonoelectrochemical Anodization.

This study aimed to investigate the fabrication and characterization of hexagonal titanium dioxide nanotubes (hTNTs) compared to compact TiO2 layers, focusing on their structural, electrochemical, corrosion, and mechanical properties. The fabrication process involved the sonoelectrochemical anodization of titanium foil in various electrolytes to obtain titanium oxide layers with different morphologies. Scanning electron microscopy revealed the formation of well-ordered hexagonal TNTs with diagonals in the range of 30-95 nm and heights in the range of 3500-4000 nm (35,000-40,000 Å). The electrochemical measurements performed in 3.5% NaCl and Ringer's solution confirmed a more positive open-circuit potential, a lower impedance, a higher electrical conductivity, and a higher corrosion rate of hTNTs compared to the compact TiO2. The data revealed a major drop in the impedance modulus of hTNTs, with a diagonal of 46 ± 8 nm by 97% in 3.5% NaCl and 96% in Ringer's solution compared to the compact TiO2. Nanoindentation tests revealed that the mechanical properties of the hTNTs were influenced by their diagonal size, with decreasing hardness and Young's modulus observed with an increasing diagonal size of the hTNTs, accompanied by increased plastic deformation. Overall, these findings suggest that hTNTs exhibit promising structural and electrochemical properties, making them potential candidates for various applications, including biosensor platforms.

Structural, Electrical and Corrosion Properties of Bulk Ti-Cu Alloys Produced by Mechanical Alloying and Powder Metallurgy.

Binary Ti100-x-Cux (x = 1.6 and 3.0 wt.%) alloys were produced by the application of mechanical alloying and powder metallurgy processes. The influence of the copper concentration in titanium on the microstructure and properties of bulk alloys was investigated. The synthesized materials were characterized by an X-ray diffraction technique, scanning electron microscopy, and chemical composition determination. The electrochemical and corrosion properties were also investigated. Cold compaction and sintering reduced the content of α-Ti content in Ti98.4-Cu1.6 and Ti97-Cu3 alloys to 92.4% and 83.7%, respectively. Open Circuit Potential measurements showed a positive shift after the addition of copper, suggesting a potential deterioration in the corrosion resistance of the Ti-Cu alloys compared to pure Ti. Electrochemical Impedance Spectroscopy analysis revealed significant improvement in electrical conductivity after the addition of copper. Corrosion testing results demonstrated compromised corrosion resistance of Ti-Cu alloys compared to pure Ti. In summary, the comprehensive investigation of Ti100-x-Cux alloys provides valuable insights for potential applications in biosensing.

Shedding light on the problem: Influence of the radiator power, source-sample distance, and exposure time on the performance of UV-C lamps in laboratory and real-world conditions.

Effective surface disinfection is crucial for preventing the spread of pathogens in hospitals. Standard UltraViolet-C (UV-C) lamps have been widely used for this purpose, but their disinfection efficiency under real-world conditions is not well understood. To fill this gap, the influence of the power of the ultraviolet radiator, source-sample distance, and exposure time on the performance of UV-C lamps against Escherichia coli and Staphylococcus epidermidis were experimentally determined in the laboratory and hospital. The obtained results showed that the UV irradiance and, thus, the UV-C disinfection efficiency decreased significantly at distances greater than 100 cm from the UV-C lamp. Moreover, increasing the total power of the radiators does not improve the performance of UV-C lamps under real conditions. The UV-C disinfection efficiency greater than 90% was achieved only under laboratory conditions at a close distance from the UV-C lamp, i.e., 10 cm. These findings provide novel insights into the limitations of UV-C lamps in real-world conditions and highlight the need for more effective disinfection strategies in hospitals.

Evaluation of biofilm formation on acrylic resins used to fabricate dental temporary restorations with the use of 3D printing technology.

BACKGROUND: Temporary implant-retained restorations are required to support function and esthetics of the masticatory system until the final restoration is completed and delivered. Acrylic resins are commonly used in prosthetic dentistry and lately they have been used in three-dimensional (3D) printing technology. Since this technology it is fairly new, the number of studies on their susceptibility to microbial adhesion is low. Restorations placed even for a short period of time may become the reservoir for microorganisms that may affect the peri-implant tissues and trigger inflammation endangering further procedures. The aim of the study was to test the biofilm formation on acrylamide resins used to fabricate temporary restorations in 3D printing technology and to assess if the post-processing impacts microbial adhesion. METHODS: Disk-shaped samples were manufactured using the 3D printing technique from three commercially available UV-curable resins consisting of acrylate and methacrylate oligomers with various time and inhibitors of polymerization (NextDent MFH bleach, NextDent 3D Plus, MazicD Temp). The tested samples were raw, polished and glazed. The ability to create biofilm by oral streptococci (S. mutans, S. sanguinis, S. oralis, S. mitis) was tested, as well as species with higher pathogenic potential: Staphylococcus aureus, Staphylococcus epidermidis and Candida albicans. The roughness of the materials was measured by an atomic force microscope. Biofilm formation was assessed after 72 h of incubation by crystal violet staining with absorbance measurement, quantification of viable microorganisms, and imaging with a scanning electron microscope (SEM). RESULTS: Each tested species formed the biofilm on the samples of all three resins. Post-production processing resulted in reduced roughness parameters and biofilm abundance. Polishing and glazing reduced roughness parameters significantly in the NextDent resin group, while glazing alone caused significant surface smoothing in Mazic Temp. A thin layer of microbial biofilm covered glazed resin surfaces with a small number of microorganisms for all tested strains except S. oralis and S. epidermidis, while raw and polished surfaces were covered with a dense biofilm, rich in microorganisms. CONCLUSIONS: UV-curing acrylic resins used for fabricating temporary restorations in the 3D technology are the interim solution, but are susceptible to adhesion and biofilm formation by oral streptococci, staphylococci and Candida. Post-processing and particularly glazing process significantly reduce bacterial biofilm formation and the risk of failure of final restoration.

Numerical Analyses of Fracture Mechanism of the Pelvic Ring during Side-Impact Load.

The aim of this study is the analysis of the multiple pelvis fracture mechanism in side-impact dynamic load cases. The elaborated numerical model of a pelvis complex includes pelvic and sacral bones as well as soft tissues such as ligaments and cartilages. The bone has been modelled as a viscoelasticity material based on the Johnson-Cook model. The model parameters have been chosen based on the experimental data. The uniqueness of a presented approach refers to the selection of crack criteria for the bone. Thus, it was allowed to analyse the process of multiple fractures inside the pelvic bones. The analysis was evaluated for the model in which the deformation rate influences the bone material properties. As a result, the stress distributions inside particular bones were changed. It has been estimated that the results can vary by 50% or even more depending on the type of boundary conditions adopted. The second step of work was a numerical analysis of military vehicle subjected to an IED. An analysis of the impactor's impact on the pelvis of the Hybrid ES-2RE mannequin was conducted. It was shown that the force in the pelvis exceeds the critical value by a factor of 10. The results of the numerical analysis were then used to validate the model of a military vehicle with a soldier. It was shown that for the adopted loading conditions, the critical value of the force in the pelvis was not exceeded.

Spectrum of Bacterial Pathogens from Urinary Infections Associated with Struvite and Metabolic Stones.

OBJECTIVE: The purposes of this multi-center study were to evaluate the rate of infection stones and to evaluate the urine cultures of patients with infection stones. MATERIALS: Charts of adulpatients with urinary stones were reviewed and data on stone analyses and urine cultures were collected. RESULTS: In total, 1204 renal stone formers (RSFs) from 10 countries were included (776 males, 428 females). Fifty-six patients (4.6%) had struvite stones. The highest frequency of struvite stones was observed in India (23%) and Pakistan (18%). Lower rates were reported in Canada (2%), China (3%), Argentina (3%), Iraq (3%), Italy (3.5%) and Poland (3%), and intermediate rates in Egypt (5.5%) and Bulgaria (5.4%). Urine cultures were retrieved from 508 patients. Patients with struvite stones had a positive culture in 64.3% of the samples and patients with other stones, in 26.7%. In struvite stones, the most common isolates were Escherichia coli (27.7%) and Proteus spp. (27.7%), followed by Klebsiella spp. (16.7%); in other types of stone, it was Escherichia coli (47.6%), followed by Gram-positive bacteria (14.0%) Conclusions: The struvite stone composition was associated with a urinary infection, although an infection was not demonstrable with a conventional midstream urine culture in about 30%.

Personalized, 3D- printed fracture fixation plates versus commonly used orthopedic implant materials- biomaterials characteristics and bacterial biofilm formation.

Additive manufacturing enabled the development of personalized, ideally fitting medical devices. The topography of the surface of the 3D-printed implant may not only facilitate its integration but also cause its rejection, as the surface may become a reservoir for different bacterial strains. In this study, the innovative, raw, 3D- printed fracture fixation plates, manufactured by using selective laser melting (SLM) from Ti-6Al-4V were compared with commercially available, surface-modified plates commonly used in orthopedic surgery. The topography surface of the plates was studied by atomic force microscopy. Susceptibility to the development of biofilm was tested for Staphylococcus epidermidis, Staphylococcus aureus and Streptococcus mutans by using crystal violet staining of biomass, confocal, and scanning electron microscopy (SEM). 3D- printed plates showed higher roughness (Sa=131.0 nm) than commercial plates (CP1 and CP2), Sa= 60.67 nm and Sa=55.48 nm, respectively. All strains of bacteria colonized 3D- printed raw plates more densely than commercial plates. The microscopic visualization showed biofilm mostly in irregular cavities of printed plates while on commercial plates it was mainly located along the edges. The research has indicated that there is need for further development of this technology to optimize its effectiveness and safety.

Encrustation of the ureteral double-J Stents made of styrene/ethylene/butylene and polyurethane before and after implantation.

PURPOSE: The aim of this study was to determine the affinity to crystal, calculi and biofilm deposition on ureteral double-J stents (DJ stents) after ureterorenoscopic-lithotripsy procedure (URS-L). The analysis was performed in two aspects: to determine which material used for fabricating ureteral stents promotes encrustation and which part of the DJ stents is the most vulnerable for blockage. METHODS: One hundred and twenty patients with an indwelling DJ stent duration between 7 and 78 days were included in this study. The encrustation of DJ stents was characterized by scanning electron microscopy (SEM), and the mechanical properties of DJ stents were examined using the standard MTS Micro Bionix tensile test. RESULTS: This study showed that polyurethane catheters have a much higher affinity for encrustation than styrene/ethylene/butylene block copolymer. Obtained results indicated the proximal (renal pelvis) and distal (urinary bladder) part is the most susceptible to post-URS-L fragments and urea salt deposition. Both the DJ ureteral stents' outer and inner surfaces were completely covered even after 7 days of implantation. CONCLUSIONS: Performed analysis pointed out that polyurethane DJ stents have a much higher affinity for encrustation of calculi and NaCl crystals compared to the silicone-based copolymer. The surface of the ureteral stents needs improvement to minimize salt and kidney stone deposition, causing pre-biofilm formation and the occurrence of defects and cracks.

Fabrication of Electrochemical Biosensor Based on Titanium Dioxide Nanotubes and Silver Nanoparticles for Heat Shock Protein 70 Detection.

This paper presents the fabrication methodology of an electrochemical biosensor for the detection of heat shock protein 70 (HSP70) as a potential tumor marker with high diagnostic sensitivity. The sensor substrate was a composite based on titanium dioxide nanotubes (TNTs) and silver nanoparticles (AgNPs) produced directly on TNTs by electrodeposition, to which anti-HSP70 antibodies were attached by covalent functionalization. This manuscript contains a detailed description of the production, modification, and the complete characteristics of the material used as a biosensor platform. As-formed TNTs, annealed TNTs, and the final sensor platform-AgNPs/TNTs, were tested using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction analysis (XRD). In addition, open circuit potential (OCP), electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV) of these substrates were used to assess the influence of TNTs modification on their electrochemical characteristics. The EIS technique was used to monitor the functionalization steps of the AgNPs/TNTs electrode and the interaction between anti-HSP70 and HSP70. The produced composite was characterized by high purity, and electrical conductivity improved more than twice compared to unmodified TNTs. The linear detection range of HSP70 of the developed biosensor was in the concentration range from 0.1 to 100 ng/mL.

The affinity for dialysate species of thermally modified titania nanotubes under static and dynamic conditions.

PURPOSE: During the dialysis process, hemolysis is the most frequently occurring problem to solve. Titanium dioxide nanotubes (TNTs) can be considered as a material preventing hemodialysis or blood species deposition thanks to their unique properties, i.e., hydrophilicity, smooth surface, and antibacterial. The purpose of this work was the electrochemical, chemical, and morphological characteristics of the TNTs and the evaluation of the possibility of using them as filter parts in dialysis techniques. METHODS: The tests were carried out on as-formed TNTs with a diameter of 50 ± 5 nm and 1000 ± 100 nm in height, and TNTs thermally modified in air atmosphere temperatures ranging from 350 to 550 °C. Electrochemical and microscopic analyses were performed both in the static and dynamic system of dialysis fluid (flow rate: 250 cm3 /min). Additionally, deposition or damage of blood cells was specified during the ex vivo dialysis experiment. RESULTS: Obtained results proved relationship between electrochemical properties of TNTs and the method of their modification. The results demonstrated that the TNTs annealed at 450 °C TNTs can be potentially applied for constructions dialysis membrane in the hemodialysis area due to their most stable stationary potential in dialysate, the highest value of impedance modulus, and the most favourable electrokinetic properties. Additionally, it was confirmed that annealed process causes improvement of corrosion resistance and protective properties for TNTs in the dialysis fluid. CONCLUSIONS: The result allowed for the conclusion that annealing is responsible for reduction of adsorption properties of TNTs, though this titanium dioxide nanotube still can be used as filter part in haemodialysis.

Surface analysis of ureteral stent before and after implantation in the bodies of child patients.

The aim of this work was to determine which part of a double-J ureteral stent (DJ stents) showed the highest tendency to crystal, calculi, and biofilm deposition after ureterorenoscopic-lithotripsy procedure (URS-L) to treat calcium oxalate stones. Additionally, the mechanical strength and the stiffness of DJ stents were evaluated before and after exposure to urine. Obtained results indicated that the proximal (renal pelvis) and distal (urinary bladder) part is the most susceptible for post-URS-L fragments and urea salt deposition. Both, the outer and inner surfaces of the DJ ureteral stents were completely covered even after 7 days of implantation. Encrustation of DJ stents during a 31-day period results in reducing the Young's modulus by 27-30%, which confirms the loss of DJ stent elasticity and increased probability of cracks or interruption. Performed analysis pointed to the need to use an antibacterial coating in the above-mentioned part of the ureteral stent to prolong its usage time and to prevent urinary tract infection.

Electrodes Based on a Titanium Dioxide Nanotube-Spherical Silver Nanoparticle Composite for Sensing of Proteins.

The aim of the research was to provide electrochemical, chemical, phase, and microscopic characteristics of electrodes based on titanium dioxide nanotubes (TNTs) containing uniformly deposited, nonagglomerated spherical silver nanoparticles (AgNPs). The nanoparticles were produced with the use of electrodeposition and sputter deposition methods. This paper presents the results of research of these platforms with the use of the following techniques: electrochemical impedance spectroscopy, X-ray diffraction analysis, X-ray photoelectron spectroscopy, and scanning electron microscopy. Evaluation of the adsorption of proteins-bovine serum albumin (BSA)-was carried out to establish the possibility of the use of the electrodes in a low-cost, simple detection system without surface functionalization. The research proved that the AgNP deposition facilitated the electron transfer increasing their conductivity properties as well as promoting the protein adsorption. The AgNPs/TNT electrodes showed a high selectivity to the BSA-anti-BSA complex. Half an hour of immobilization was enough to completely saturate the TNT electrodes, whereas for AgNPs/TNTs, 1 h of immobilization seemed to be not enough. The impedance parameter changes for electrodes with the AgNPs reached even about 300%. The biggest changes were noted for the platform obtained using cyclic voltammetry, so it is the best detection platform for biosensing.

Impedimetric Detection of Femtomolar Levels of Interleukin6, Interleukin 8, and Tumor Necrosis Factor Alpha Based on Thermally Modified Nanotubular Titanium Dioxide Arrays.

An inexpensive, easy to prepare, and label-free electrochemical impedance spectroscopy-based biosensor has been developed for the selective detection of human interleukin 6 (IL-6), interleukin 8 (CXCL8, IL-8), and tumor necrosis factor (TNFα)-potential inflammatory cancer biomarkers. We describe a, so far, newly developed and unexplored method to immobilize antibodies onto a titanium dioxide nanotube (TNT) array by physical adsorption. Immobilization of anti-IL-6, anti-IL-8, and anti-TNFα on TNT and the detection of human IL-6, IL-8, and TNFα were examined using electrochemical impedance spectroscopy (EIS). The impedimetric immunosensor demonstrates good selectivity and high sensitivity against human biomarker analytes and can detect IL-6, IL-8, and TNFα at concentrations as low as 5 pg/mL, equivalent to the standard concentration of these proteins in human blood. The calibration curves evidenced that elaborated biosensors are sensitive to three cytokines within 5 ÷ 2500 pg/mL in the 0.01 M phosphate-buffered saline solution (pH 7.4).

Susceptibility to biofilm formation on 3D-printed titanium fixation plates used in the mandible: a preliminary study.

Background: In the oral and maxillofacial surgery, fixation plates are commonly used for the stabilization of bone fragments. Additive manufacturing has enabled us to design and create personalized fixation devices that would ideally fit any given fracture. Aim: The aim of the present preliminary study was to assess the susceptibility of 3D-printed titanium fixation plates to biofilm formation. Methods: Plates were manufactured using selective laser melting (SLM) from Ti-6Al-4 V. Reference strains of Streptococcus mutans, Staphyloccocus epidermidis, Staphylococcus aureus, Lactobacillus rhamnosus, and Candida albicans, were tested to evaluate the material's susceptibility to biofilm formation over 48 hours. Biofilm formations were quantified by a colorimetric method and colony-forming units (CFU) quantification. Scanning electron microscopy (SEM) visualized the structure of the biofilm. Results: Surface analysis revealed the average roughness of 102.75 nm and irregular topography of the tested plates. They were susceptible to biofilm formation by all tested strains. The average CFUs were as follows: S. mutans (11.91 x 107) > S.epidermidis (4.45 x 107) > S. aureus (2.3 x 107) > C.albicans (1.22 x 107) > L. rhamnosus (0.78 x 107). Conclusions: The present preliminary study showed that rough surfaces of additively manufactured titanium plates are susceptible to microbial adhesion. The research should be continued in order to compare additively manufactured plates with other commercially available osteotomy plates. Therefore, we suggest caution when using this type of material.

Comparison of Gold Nanoparticles Deposition Methods and Their Influence on Electrochemical and Adsorption Properties of Titanium Dioxide Nanotubes.

The increasing interest of attachment of gold nanoparticles (AuNPs) on titanium dioxide nanotubes (TNTs) has been devoted to obtaining tremendous properties suitable for biosensor applications. Achieving precise control of the attachment and shape of AuNPs by methods described in the literature are far from satisfactory. This work shows the comparison of physical adsorption (PA), cyclic voltammetry (CV) and chronoamperometry (CA) methods and the parameters of these methods on TNTs properties. The structural, chemical, phase and electrochemical characterizations of TNTs, Au/TNTs, AuNPs/TNTs are carried out using scanning electron microscopy (SEM), electrochemical impedance spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy. The use of PA methods does not allow the deposition of AuNPs on TNTs. CV allows easily obtaining spherical nanoparticles, for which the diameter increases from 20.3 ± 2.9 nm to 182.3 ± 51.7 nm as a concentration of tetrachloroauric acid solution increase from 0.1 mM to 10 mM. Increasing the AuNPs deposition time in the CA method increases the amount of gold, but the AuNPs diameter does not change (35.0 ± 5 nm). Importantly, the CA method also causes the dissolution of the nanotubes layer from 1000 ± 10.0 nm to 823 ± 15.3 nm. Modification of titanium dioxide nanotubes with gold nanoparticles improved the electron transfer and increased the corrosion resistance, as well as promoted the protein adsorption. Importantly, after the deposition of bovine serum albumin, an almost 5.5-fold (324%) increase in real impedance, compared to TNTs (59%) was observed. We found that the Au nanoparticles-especially those with smaller diameter-promoted the stability of bovine serum albumin binding to the TNTs platform. It confirms that the modification of TNTs with gold nanoparticles allows the development of the best platform for biosensing applications.

Influence of geometry and annealing temperature in argon atmosphere of TiO2 nanotubes on their electrochemical properties.

PURPOSE: In this paper, electrochemical properties of the as-formed and thermally treated titanium dioxide (TiO2) nanotubes with diameter in the range of 20-100 nm and height in the range of 100-1000 nm were presented. In addition, the effects of annealing temperature (450-550 °C) on the electrochemical characteristics of these structures, as well as the influence of diameter and height of TiO2 nanotubes on these properties were examined. The results were referred to a compact TiO2 layer (100 nm thick). METHODS: The electrochemical test included open circuit potential, impedance spectroscopy and cyclic voltammetry measurements. The scanning electron microscope with energy dispersive spectroscopy analyser, x-ray photoelectron spectroscopy, and x-ray diffraction analysers were used for surface morphology characterisation as well as elemental, phase and chemical composition of TiO2 layers. RESULTS: It was found that nanotubes with the diameter of 50 and 75 nm (height of 1000 nm) annealed at 550 °C exhibit the lowest impedance and phase angle values. However, the voltammetric detection of potassium ferricyanide indicated that the closest to 1 Ipc /Ipa ratio were shown by nanotubes with a diameter of 50 and 75 nm annealed at 450 °C. CONCLUSIONS: On the basis of performed analysis, it can be stated that the TiO2 layer with nanotubes of 50 nm in diameter and of 1000 nm in height, annealed in 450 °C may be indicated as the ones having the most favourable sensing and biosensing properties.

Electrochemical Evaluation of the Compact and Nanotubular Oxide Layer Destruction under Ex Vivo Ti6Al4V ELI Transpedicular Screw Implantation.

Nano-engineered implants are a promising orthopedic implant modification enhancing bioactivity and integration. Despite the lack of destruction of an oxide layer confirmed in ex vivo and in vivo implantation, the testing of a microrupture of an anodic layer initiating immune-inflammatory reaction is still underexplored. The aim of this work was to form the compact and nanotubular oxide layer on the Ti6Al4V ELI transpedicular screws and electrochemical detection of layer microrupture after implantation ex vivo by the Magerl technique using scanning electron microscopy and highly sensitive electrochemical methods. For the first time, the obtained results showed the ability to form the homogenous nanotubular layer on an Ti6Al4V ELI screw, both in α and ß-phases, with favorable morphology, i.e., 35 ÷ 50 ± 5 nm diameter, 1500 ± 100 nm height. In contrast to previous studies, microrupture and degradation of both form layers were observed using ultrasensitive electrochemical methods. Mechanical stability and corrosion protection of nanotubular layer were significantly better when compared to compact oxide layer and bare Ti6Al4V ELI.

Evaluation of the Antibacterial Activity of Ag- and Au-Nanoparticles Loaded TiO2 Nanotubes.

Current research on the antibacterial properties of implant surfaces has focused on using titanium nanotubes (TNTs) with diameters of 100 and 200 nm, which simultaneously show the best antibacterial properties, poor osseointegration, and ability to immobilize proteins. Therefore, the research aimed to develop an implantable material based on titanium dioxide nanotubes with a diameter of 50 nm doped with silver (AgNPs) and gold nanoparticles (AuNPs), indicating good absorption and antibacterial properties. Moreover, metallic nanoparticles deposited by varying methods should maintain sphericity and lack of agglomeration. For this purpose, the surface charge, wettability, stability of nanoparticles, and antibacterial properties against Gram-positive and Gram-negative bacteria, i. e., Staphylococcus epidermidis, Streptococcus mutans, and Pseudomonas aeruginosa , were performed. Obtained results indicate a greater resistance to leaching of silver nanoparticles compared to gold nanoparticles. These results are reflected in microbiological studies, both into the time and the effectiveness of the implantable material's antibacterial activity. A greater antibacterial effect of AgNPs than AuNPs has been confirmed. Also, AgNPs inhibit the multiplication of Gram-negative bacteria to a greater extent than Gram-positive bacteria. It has been proven that the TNT platforms deposited with metal nanoparticles via the voltammetric method are more effective in deactivating microorganisms. Besides, the results have proven that smaller TNTs effectively reduce live bacteria as nanotubes with a diameter of 100 and 200 nm.

The Influence of the Parameters of a Gold Nanoparticle Deposition Method on Titanium Dioxide Nanotubes, Their Electrochemical Response, and Protein Adsorption.

The goal of this research was to find the best conditions to prepare titanium dioxide nanotubes (TNTs) modified with gold nanoparticles (AuNPs). This paper, for the first time, reports on the influence of the parameters of cyclic voltammetry process (CV) -based AuNP deposition, i.e., the number of cycles and the concentration of gold salt solution,on corrosion resistance and the capacitance of TNTs. Another innovation was to fabricate AuNPs with well-formed spherical geometry and uniform distribution on TNTs. The AuNPs/TNTs were characterized using scanning electron microscopy, X-ray photoelectron spectroscopy, electrochemical impedance spectroscopy, and open-circuit potential measurement. From the obtained results,the correlation between the deposition process parameters, the AuNP diameters,and the electrical conductivity of the TNTs was found in a range from 14.3 ± 1.8 to 182.3 ± 51.7 nm. The size and amount of the AuNPs could be controlled by the number of deposition cycles and the concentration of the gold salt solution.The modification of TNTs using AuNPs facilitated electron transfer, increased the corrosion resistance, and caused better adsorption properties for bovine serum albumin.

Influence of the Silver Nanoparticles (AgNPs) Formation Conditions onto Titanium Dioxide (TiO2) Nanotubes Based Electrodes on Their Impedimetric Response.

This paper presents the comparison of the effects of three methods of production of silver spherical and near-spherical nanoparticles (AgNPs) on the titanium dioxide nanotubes (TNT) base: cyclic voltammetry, chronoamperometry, and sputter deposition. It also evaluates the influence of silver nanoparticles on the electrochemical properties of the developed electrodes. The novelty of this research was to fabricate regular AgNPs free of agglomerates uniformly distributed onto the TNT layer, which has not been accomplished with previous attempts. The applied methods do not require stabilizing and reducing reagents. The extensive electrochemical characteristic of AgNP/TNT was performed by open circuit potential and electrochemical impedance spectroscopy methods. For AgNPs/TNT obtained by each method, the impedance module of these electrodes was up to 50% lower when compared to TNT, which means that AgNPs enabled more efficient electron transfer due to the effective area increase. In addition, the presence of nanoparticles increases the corrosion resistance of the prepared electrodes. These substrates can be used as electrochemical sensors due to their high electrical conductivity, and also as implants due to the antibacterial properties of both the TNT and AgNPs.