Bio Nano Consulting

The increasing incidenceof drug-resistant bacterial strains, suchas methicillin-resistant Staphylococcus aureus (MRSA), poses a significant threat to public health owing to theirhigh morbidity and mortality rates. Conventional methods for MRSAdetection are expensive and time-consuming, necessitating advancedtechnological solutions. This study aimed to develop a direct detectionstrategy for MRSA by using magnetic nanoparticles (MNPs) as captureprobes and quantum dots (QDs) as fluorescent detection probes. MNPcapture probes were prepared by the coprecipitation of Fe3O4 NPs, followed by co-condensation to obtain amine-functionalizedsilica coatings on Fe3O4 NPs (amine-Si@MNPs).Carboxyl modification of amine-Si@MNPs was achieved via the hydrolyticcleavage of succinic anhydride. QDs were prepared using a one-potchemical reduction method for CdTe core, followed by inorganic epitaxialgrowth of ZnS shell (CdTe/ZnS QDs). The size, morphology, surfacefunctionalization, and magnetic and optical properties of the nanoprobeswere characterized using several techniques. Both the nanoprobes wereconjugated to protein A using carbodiimide chemistry. QD–proteinA was conjugated to an anti-PBP2a antibody that specifically targetsMRSA. In contrast, MNP–protein A was conjugated with humanIgG to target outer membrane protein A of MRSA. MRSA detection wasachieved by mixing the sample with the QD detection probe, followedby MNP capture probe, magnetic separation, and fluorescence measurements.Detection was achieved within ∼25 min, with a detection limitof 5 colony-forming units (CFU)/mL. The selectivity of this methodwas investigated by using mixed cultures of various bacterial isolates.

With the extensive use of silver nanoparticles (AgNPs) in various consumer products their potential toxicity is of great concern especially for highly sensitive population groups such as pregnant women and even the developing fetus. To understand if AgNPs are taken up and cross the human placenta, we studied their translocation and accumulation in the human ex vivo placenta perfusion model by single particle ICP-MS (spICP-MS). The impact of different surface modifications on placental transfer was assessed by AgNPs with two different modifications: polyethylene glycol (AgPEG NPs) and sodium carboxylate (AgCOONa NPs). AgNPs and ionic Ag were detected in the fetal circulation in low but not negligible amounts. Slightly higher Ag translocation across the placental barrier for perfusion with AgPEG NPs and higher AgNP accumulation in placental tissue for perfusion with AgCOONa NPs were observed. Since these AgNPs are soluble in water, we tried to distinguish between the translocation of dissolved and particulate Ag. Perfusion with AgNO3 revealed the formation of Ag containing NPs in both circulations over time, of which the amount and their size in the fetal circulation were comparable to those from perfusion experiments with both AgNP types. Although we were not able to clarify whether intact AgNPs and/or Ag precipitates from dissolved Ag cross the placental barrier, our study highlights that uptake of Ag ions and/or dissolution of AgNPs in the tissue followed by re-precipitation in the fetal circulation needs to be considered as an important pathway in studies of AgNP translocation across biological barriers.

It is now possible to create atomically thin regions of dopant atoms in silicon patterned with lateral dimensions ranging from the atomic scale (angstroms) to micrometers. These structures are building blocks of quantum devices for physics research and they are likely also to serve as key components of devices for next-generation classical and quantum information processing. Until now, the characteristics of buried dopant nanostructures could only be inferred from destructive techniques and/or the performance of the final electronic device; this severely limits engineering and manufacture of real-world devices based on atomic-scale lithography. Here, we use scanning microwave microscopy (SMM) to image and electronically characterize three-dimensional phosphorus nanostructures fabricated via scanning tunneling microscope-based lithography. The SMM measurements, which are completely nondestructive and sensitive to as few as 1900 to 4200 densely packed P atoms 4 to 15 nm below a silicon surface, yield electrical and geometric properties in agreement with those obtained from electrical transport and secondary ion mass spectroscopy for unpatterned phosphorus δ layers containing ~1013 P atoms. The imaging resolution was 37 ± 1 nm in lateral and 4 ± 1 nm in vertical directions, both values depending on SMM tip size and depth of dopant layers. In addition, finite element modeling indicates that resolution can be substantially improved using further optimized tips and microwave gradient detection. Our results on three-dimensional dopant structures reveal reduced carrier mobility for shallow dopant layers and suggest that SMM could aid the development of fabrication processes for surface code quantum computers.

Aerosol-assisted chemical vapour deposition of substituted polyoxometalates H4 [PMo11 VO40 ], H7 [PMo8 V4 O40 ], [nBu4 N]4 [PVW11 O40 ] and [nBu4 N]5 [PV2 W10 O40 ] resulted in the formation of vanadium-doped metal oxide thin films. Depositions were carried out at 550 °C in methanol or acetonitrile for the POMs that contained molybdenum or tungsten, respectively. The as-deposited films were X-ray amorphous and relatively non-adherent. However, on annealing in air at 600 °C, decolourised translucent films that were more mechanically robust were obtained. Films deposited from H4 [PMo11 VO40 ] and H7 [PMo8 V4 O40 ] consisted of V-doped MoO3 in the orthorhombic phase and films from [nBu4 N]4 [PVW11 O40 ] and [nBu4 N]5 [PV2 W10 O40 ] comprised of monoclinic V-doped WO3 . All films were fully characterised by using X-ray photoelectron spectroscopy, energy-dispersive X-ray diffraction, scanning electron microscopy and UV/Vis spectroscopy.

On page 28, a fundamental study of the direct resistive heating of emulsion-templated graphene aerogels demonstrates reliable, fast, energy-efficient and uniform temperature control of the graphene framework. R. Menzel, M. S. P. Shaffer, and team's findings lay a framework that may be exploited in a wide range of novel applications for nanocarbon aerogels, including flow-through local gas heaters, temperature-sensitive catalytic reactions, and thermally regenerable filter and storage systems.

This paper shows the aerosol assisted chemical vapour deposition of transparent, blue coloured and conductive tantalum doped titanium dioxide films from the CVD reaction of Ti(OEt)4 and Ta(OEt)5. Hall effect measurements showed the doped films to have excellent n-type electrical conductivity showing, to the best of our knowledge, the lowest reported sheet resistance ever recorded for Ta-doped TiO2 of 14 Ω sq−1. The Ta 6 atom% doped TiO2 film also showed the best electrical results with a charge carrier concentration of 1.60 × 1021 cm−3 and mobility of 1.44 cm2 V−1 s−1 making it a suitable electrode in photovoltaic devices. The doped films were multifunctional, showing good photocatalytic activity under UV-light illumination. XPS and XRD studies gave strong evidence that the Ta was entering the TiO2 lattice as Ta5+ and that a reduction of some Ti4+ to Ti3+ was observed.

Many electrical scanning probe microscopy (SPM) techniques suffer from parasitic stray EM field contributions, which give rise to low signal to noise ratio and make the image retrieval process more difficult. Here, we validate via computational modeling a calibration procedure that employs three calibration standards and three complex coefficients to obtain a black-box transfer function between the systemic reflection coefficient and the reflection coefficient at the tip of the probe, from which the impedance, capacitance and dielectric constant of nano-sized structures can be determined. We find that a 1o variation in the inclination angle of the cantilever can cause a 10% variation in the bulk systemic impedance. Experimental scanning microwave microscope measurements agree with our simulation results.

Aerosol assisted chemical vapour deposition (AACVD) was used to synthesise a TiO2–SnO2 composite film onto a glass substrate. For comparison a TiO2 film and a SnO2 film were also prepared. All films were characterised by X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and wavelength dispersive X-ray spectroscopy (WDX). XPS and WDX of the composite film revealed a TiO2 rich film with a high level of SnO2 segregation at the surface. Highly structured pyramid-like features gave rise to hydrophobic films with static water contact angles of 134°. Photocatalytic activities were determined by monitoring the degradation of intelligent ink (containing Resazurin redox dye) via UV-visible spectroscopy. Under UVA irradiation, the TiO2 film only began to degrade the dye after being irradiated in excess of 100 minutes, whereas the composite TiO2–SnO2 film required only 6 minutes of irradiation before degradation was observed. The formal quantum efficiency (FQE) for the TiO2–SnO2 composite was determined to be 1.01 × 10−2 molecules per incident photon and the formal quantum yield (FQY) was 1.17 × 10−2 molecules per absorbed photon. This is an order of magnitude superior to Pilkington Activ™ self-cleaning glass a commercial self-cleaning TiO2 coating on glass. This improved photocatalytic activity is attributed to the presence of electron scavenging SnO2 sites that increase charge separation and the increased surface area due to the highly structured morphology.

Layered double hydroxides (LDHs) are promising materials for CO2 sorption, although improvements in performance are required for practical applications. In the current study, the CO2 sorption capacity and multi-cycle stability were both increased by introducing an open supporting framework of multi-walled carbon nanotubes (MWNTs). This nanostructured inert network provides a high surface area, maximizing the gas accessibility and minimizing coarsening effects. Specifically, LDH nanoparticles were precipitated directly onto MWNTs, initially oxidised to ensure a favourable electrostatic interaction and hence a good dispersion. The dependence of the structural and physical properties of the Mg–Al LDH grown on MWNT supports has been studied, using electron microscopy, X-ray diffraction, thermogravimetric analysis (TGA), and BET surface area, and correlated with the CO2 sorption capacity, established via TGA and temperature programmed desorption measurements. The use of a MWNT support was found to improve the absolute capacity and cycle stability of the hybrid adsorbent under dry conditions.

The activation of synthetic hydrotalcite, the carbonated layered double hydroxide (LDH) with ratio Mg 2+/Al 3+ = 3 and structural formula [Mg 6Al 2(OH) 16] 2+· CO 3 2-n(H 2O), has been investigated using neutron and X-ray diffraction. In situ neutron diffraction was used to follow the structural phase transformations during the thermal decomposition (calcination) of hydrotalcite under vacuum in the temperature range 298-723 K, and during which the residual gas evolved by the sample was analysed by mass spectrometry. Detailed structural information of the LDH and mixed metal oxides (MMOs) was extracted from both the Bragg peaks and the total scattering. These two analysis techniques provide complementary insight into the relevant transition mechanisms, since Bragg diffraction originates from long-range periodicities within the samples while total scattering reveals the subtleties of the local atomic environment. This latter information is particularly important for our understanding of catalytic activity since it elucidates the local metal coordination. We find that, during the calcination process, the local environment around the metal centres is robust, as the various stages during the phase transition have identical local structures. The implications of these new results for the nature of the MMOs is discussed in relation to the well-studied, reverse, rehydration reaction, and the high propensity of trivalent Al ions to migrate to tetrahedrally-coordinated lattice sites.