Titanium Nanoclusters Research Articles

The PVDF-HFP/Ag NWs-based wide electrochemical stability window ECL system for miRNA 21 detection in gastric cancer ascites

Due to the limitation of the electrochemical stability window (ESW), the high potential usually led to more side reactions during the electrochemical reaction. Therefore, a novel electrochemiluminescence (ECL) sensor with wide ESW was constructed in this study. Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)/silver nanowires (Ag NWs) composite was used as the substrate of the ECL biosensor. PVDF-HFP was good mechanical strength, high temperature stability and electrochemical stability. Meanwhile, Ag NWs with excellent electrical conductivity, light transmission and flexibility were employed to improve the charge transfer efficiency in the PVDF-HFP and provide binding sites for biomolecules. The optimized ESW of PVDF-HFP/Ag NWs/GCE was up to 3.717 V. Furthermore, titanium nanoclusters (Ti NCs) were synthesized and used as the aggregation-induced ECL (AIECL) probe. In addition, the biosensor achieved the good quantitative detection of miRNA 21 in ascites of gastric cancer patients within the linear range of 1 fM − 1 nM.

Engineering of TiN (N = 1 – 15) nanoclusters by doping osmium impurity

Bimetallic transition metal nanoclusters have attracted significant attention in recent years due to their wide range of applications such as heterogeneous catalysts, electrochemistry and alloy design. However many studies were reported on pure transition metal nanoclusters and bimetallic of late transition metal nanoclusters. In this study the density functional theory (DFT) with PBEsol exchange correlation functional was employed to investigate the structural and electronic properties of TiN-1Os (N = 2-16) nanoclusters. The calculations showed that osmium impurity mostly prefers to be encapsulated by titanium nanoclusters. The binding energies gradually decrease with the cluster size N. The Os dopant was found to enhance the binding energy of titanium nanoclusters. The relative stability or second order energies showed that Ti6Os and Ti12Os clusters are the most stable. Interestingly, osmium dopant converted the nanocluster with 13 atoms to be the most stable. Furthermore, the dissociation energy or first order energies showed an excellent correlation with the relative stability trend. The HOMO-LUMO revealed the lowest energy gap at Ti12Os (N = 13) which correlates well with the predicted binding energy, relative stability and dissociation energy.

Synthesis of Fluorescent Titanium Nanoclusters at ambient temperature for highly sensitive and selective detection of Creatine Kinase MM in myocardial infarction

Fluorescent-based biosensing in Photoluminescence nanomaterials has emerged as a new sensing platform commonly used for disease diagnosis. However, the synthesis of Titanium nanoclusters is highly challenging since Titanium is easily oxidized into TiO2 at ambient temperature. To overcome this problem, we used an acidic medium and simple and robust protocol to synthesize the Titanium nanoclusters of 3–4 nm diameter, which could report the first fluorescent Titanium nanoclusters. New approaches for the novel synthesis of TiNCs can be used for rapid sensing of myocardial infarction (cardiac arrest). In converting creatine to phosphocreatine, CK-MM activates the reaction to convert ATP to ADP, thereby releasing the phosphate groups. Titanium nanoclusters bind strongly to the phosphate group and then quench the Fluorescence. Thus, this phenomenon can be further applied for quantification approaches. The quenching of fluorescence intensity with CK-MM concentration is linear with R² = 0.9829. The current approach can be applied for CK-MM sensing for a wide concentration range (0.625 U/L - 10 U/L). The detection limit was 0.2513 ng/ml in aqueous medium and 0.3465 ng/ml in human serum with high sensitivity when compared with the previous reported methods. Also, this is the first fluorescent-based sensing method to detect CK- MM. The fluorescent TiNCs is a novel platform to be widely applied for the phosphopeptide and phosphoprotein analysis due to the strong and covalent bondings between Ti with P atoms in the near future in medicine, biomedicine, and biological fields.

Oxygen Atom Exchange between Gaseous CO2 and TiO2 Nanoclusters

Isotopic exchange of oxygen atoms between gaseous C18O2 and Ti16O2 nanoparticles has been studied using high-resolution Fourier transform infrared absorption and first-principles density functional theory calculations. The rate of formation of gaseous C16O2 is found to be highly dependent on the nature of the titania sample, growing with increasing calcination temperature (i.e., with decreasing surface area) for both quasi-amorphous and crystalline samples. The unprecedented faster kinetics on high-surface-area titania made from Ti(IV) isopropoxide points at fundamental differences between this material and the usual nanocrystalline TiO2 (anatase). This is attributed to unique cluster-like structure of the noncalcined ex-isopropoxide titania. The experimental observations are rationalized by calculations of the activation barriers for oxygen exchange on a (TiO2)10 cluster. The calculations predict that titanium nanoclusters with 4-fold coordinated titanium atoms have much lower barriers for O atom exchange than previously found for the oxygen defect sites on the single crystal (101) anatase surface.

Phase Transformation in Titanium Nanoparticles from First Principles

We have used molecular dynamics and first-principles calculations to investigate the structure and agglomeration of Ti nanoparticles. The results indicate that Ti nanoclusters undergo a phase transition with a change of point group symmetry. In addition, we found that titanium nanocluster growth occurred along the [0001] direction.

First principles calculations of the agglomeration of Ti nanoparticles

We have used molecular dynamics and first-principles calculations to investigate the structure, electronic properties, and agglomeration of Ti nanoparticles. The results indicate that cluster agglomeration leads to a decrease in the band gap compared with the isolated Ti13 cluster. In addition, we found that titanium nanocluster growth occurred along the [0001] direction. The difference of the atomic structures of the icosahedral Ti13 cluster and the bulk phase of titanium was also studied. The results show that spin polarization disappears when nanoparticles agglomerate.

Molecular nitrogen adsorption on individual platinum and titanium nanoclusters

Molecular nitrogen adsorption on single platinum and titanium nanoclusters is investigated by scanning tunneling microscopy and spectroscopy, including the use of an inverse scheme of spectroscopic measurements. Some regularities of the occurring processes are found.

Structure and Composition of Titanium Nanocluster Films Prepared by a Gas Aggregation Cluster Source

Structure and composition of titanium nanocluster films were studied on samples prepared by a gas aggregation cluster source based on a planar magnetron following the Haberland concept. Elemental composition of the nanoclusters was studied by X-ray photoelectron spectroscopy (XPS), their crystal structure was determined by X-ray diffraction, and their optical properties were characterized by UV–vis spectroscopy. Both as-prepared (without any additional postdeposition treatment) and annealed films were studied. Annealing of selected nanocluster films was done in air at 420 °C for 1 h followed by a natural cool-down. Titanium nanocluster films were found to oxidize immediately when exposed to ambient atmosphere. The as-prepared nanoclusters were composed of both Ti and TiO2. The nanoclusters undergo further oxidation in time and their structure and properties change. The transformation from a metal to an oxide structure of the nanoclusters upon annealing ends up in a semistable anatase crystal form of TiO2 with traces of a thermodynamically stable rutile crystal form.

Electronic structure of the nitride-like structures formed on platinum and titanium nanoclusters

The molecular nitrogen adsorption on single titanium and platinum nanoclusters was investigated by scanning tunneling microscopy and spectroscopy with the “inverted” mode of spectroscopic measurements. Certain physical characteristics of electron structure of surface covered with adsorbed nitrogen were discovered.

Morphology of Titanium Nanocluster Films Prepared by Gas Aggregation Cluster Source

AbstractTitanium nanocluster films were prepared using a gas aggregation cluster source based on a planar magnetron following a Haberland concept and using Ar as a working gas. The films were deposited in dependence on the argon pressure inside the cluster source and on the magnetron current. Prior to the analysis, deposited metal nanocluster films were allowed to oxidize in air at room temperature. Selected nanocluster films were annealed in air at 420 °C. The films were studied by TEM, SEM, and AFM in order to describe their morphology and topography. Crystal structure of the nanoclusters was estimated from electron diffraction patterns by SAD analysis. Chemical composition of the film surface was determined by XPS. Special attention was paid to describing the changes in the nanocluster films connected with ageing. magnified image

Interaction between nitrogen and single titanium clusters

The adsorption of molecular nitrogen on a single titanium nanocluster has been investigated by scanning tunneling microscopy and spectroscopy using the “inversed” method of spectroscopic measurements. It has been found that the nitride-like structures that formed during dissociative adsorption can exhibit both semiconductor (at low infills) and metallic (at high infills) conductivities. Defects of nitride-like structures (nitrogen vacancies) have been detected. The dependence that the nitride-like structure morphology has on the titanium nanocluster charge has been revealed.

Aging of nanocluster Ti/TiOx films prepared by means of gas aggregation cluster source

Nanocluster films composed of Ti and TiOx were prepared using a gas aggregation cluster source. The films were first characterized immediately after their preparation and afterwards were allowed to oxidize in air at room temperature for a given time to study their aging. Selected nanocluster films were annealed at 420°C in air for 1h. The prepared nanocluster films were studied by a variety of methods in order to fully characterize their properties. Transmission electron microscopy (TEM) was utilized to determine size of the clusters. Chemical composition of the films was determined by X-ray Photoelectron Spectroscopy (XPS) and secondary ion mass spectrometry (SIMS). Optical properties were studied using ultraviolet–visible spectroscopy (UV–vis). Special attention was paid to the description of oxidation of the titanium nanoclusters and other changes in the films connected with aging.

Gas aggregation nanocluster source — Reactive sputter deposition of copper and titanium nanoclusters

Copper and titanium nanoclusters in Ar and in Ar+O2 gas mixtures were prepared using a magnetron based gas aggregation cluster source designed for Ultra High Vacuum operation. A considerable influence of oxygen addition on the formation of clusters was observed even at oxygen-to-argon admixture levels of the order of 1:1000. A quadrupole mass filter determined nanocluster size distribution while the total deposition rate was determined by quartz crystal measurements.

Analysis of the X-ray absorption fine structure near the TiL 2, 3 edge in free titanium nanoclusters

A theoretical analysis is made of the experimental TiL2, 3 X-ray absorption near edge structure (XANES) spectra of free titanium nanoclusters containing 15–55 or 100–120 atoms. Good agreement between experimental and simulated data is obtained using the time-dependent local density approximation.

Electronic conductance of ion implanted and plasma modified polymers

The authors used the plasma immersion ion implantation and deposition technique to modify polyethylene terephthalate (PET) and by using conductive atomic force microscope, the spatial distribution of ∼10nm size titanium nanoclusters embedded in PET matrices were observed. The I-V plots showed typical metal-semiconductor junction conductivity between the conductive tip and the surface. In addition, the authors also measured the temperature dependent conductivity and fitted it well to the Mott law, which implied that the conductance arose from electron hopping process. Such technique to create the surface structure of metal/polymer nanocomposites may open an alternative way for plastic nanoelectronics.

Free small nanoclusters of titanium: XANES study

X-ray absorption near-edge structure (XANES) spectra at the Ti L 2,3-edge of small titanium nanoclusters have been studied. XANES spectra have been measured at the GasPhase beamline of Elettra synchrotron radiation facility. For theoretical interpretation of XANES, both self-consistent full multiple-scattering theory within time-dependent local density approximation (TDLDA) and non-muffin-tin finite difference method (FDM) were applied.

Solventless Acid‐Free Synthesis of Mesostructured Titania: Nanovessels for Metal Complexes and Metal Nanoclusters

AbstractA new and highly reproducible method to obtain mesostructured titania materials is introduced in this contribution. The mesostructured titania is obtained by employing self‐assembled structures of non‐ionic alkyl‐poly(ethylene oxide) surfactants as templates. The materials are produced without additional solvents such as alcohols, or even water. Only the titanium(IV) ethoxide and the surfactant (C12EO10) are needed. Water, in the form of that attached to the surfactant and from the atmosphere, induces growth of titania nanoclusters in the synthesis sol. It is indicated that these nanoclusters interact with the surfactant EO‐head groups to form a new titanotropic amphiphile. The new amphiphiles self‐assemble into titanium nanocluster–surfactant hybrid lyotropic phases, which are transformed to the final mesostructured materials by further condensation of the titania network. The titania materials can be obtained also with noble‐metal particles immobilized in the mesostructured framework. It is seen that when different metal salts are used as the metal precursors, different interactions with the titania walls are found. The materials are characterized by X‐ray diffraction (XRD), polarization optical microscopy (POM), transmission electron microscopy (TEM), UV‐vis spectroscopy, and micro‐Raman analysis.