Microfluidic-Generated Seeds for Gold Nanotriangle Synthesis in Three or Two Steps

Nanoparticle synthesis has drawn great attention in the last decades. The study of crystal growth mechanisms and optimization of the existing methods lead to the increasing accessibility of nanomaterials, such as gold nanotriangles which have great potential in the fields of plasmonics and catalysis. To form such structures, a careful balance of reaction parameters has to be maintained. Herein, a novel synthesis of gold nanotriangles from seeds derived with a micromixer, which provides a highly efficient mixing and simple parameter control is reported. The impact of the implemented reactor on the primary seed characteristics is investigated. The following growth steps are studied to reveal the phenomena affecting the shape yield. The use of microfluidic seeds led to the formation of well-defined triangles with a narrower size distribution compared to the entirely conventional batch synthesis. A shortened two-step procedure for the formation of triangles directly from primary seeds, granting an express but robust synthesis is further described. Moreover, the need for a thorough study of seed crystallinity depending on the synthesis conditions, which – together with additional parameter optimization – will bring a new perspective to the use of micromixers which are promising for scaling up nanomaterial production is highlighted.     

LSPR-Based Biosensing Enables the Detection of Antimicrobial Resistance Genes

The development of rapid, simple, and accurate bioassays for the detection of nucleic acids has received increasing demand in recent years. Here, localized surface plasmon resonance (LSPR) spectroscopy for the detection of an antimicrobial resistance gene, sulfhydryl variable β-lactamase (blaSHV), which confers resistance against a broad spectrum of β-lactam antibiotics is used. By performing limit of detection experiments, a 23 nucleotide (nt) long deoxyribonucleic acid (DNA) sequence down to 25 nm was detected, whereby the signal intensity is inversely correlated with sequence length (23, 43, 63, and 100 nt). In addition to endpoint measurements of hybridization events, the setup also allowed to monitor the hybridization events in real-time, and consequently enabled to extract kinetic parameters of the studied binding reaction. Performing LSPR measurements using single nucleotide polymorphism (SNP) variants of blaSHV revealed that these sequences can be distinguished from the fully complementary sequence. The possibility to distinguish such sequences is of utmost importance in clinical environments, as it allows to identify mutations essential for enzyme function and thus, is crucial for the correct treatment with antibiotics. Taken together, this system provides a robust, label-free, and cost-efficient analytical tool for the detection of nucleic acids and will enable the surveillance of antimicrobial resistance determinants.     

Transparent Plasmonic Nanowire Electrodes via Self‐Organised Ion Beam Nanopatterning

A self‐organised approach for the synthesis of transparent metal nanowire arrays is based on defocused ion beam sputtering. The nanowire arrays, supported on low‐cost dielectric substrates (glass slides), feature a dual functionality: they exhibit anisotropic conductivity, with sheet resistances which are reduced in comparison to those of transparent conductive oxides, and additionally they support localised plasmon resonances. The latter represents an attractive feature in view of plasmon enhanced photon harvesting applications, in which the nanostructured metal electrodes are employed as an alternative to conventional transparent conductive oxides.     

Crystallization of progesterone polymorphs using polymer-induced heteronucleation (PIHn) method

Progesterone is a natural hormone steroid used in humans for several treatments and in livestock for artificial insemination, which exhibits two polymorphic forms at ambient conditions: form 1 and form 2. Form 2 is metastable and more soluble than form 1; however, it is not suitable to use as powder raw material because it transforms into form 1 by the effects of grinding. A polymorphic screening of progesterone based on polymer-induced heteronucleation method was performed as an alternative to prepare the metastable form. Polyvinyl alcohol, hydroxypropyl methylcellulose (HPMC), dextran, gelatin, polyisoprene (PI) and acrylonitrile-butadiene (NBR) copolymer were used. Crystals were prepared from 0.5, 10 and 40?mg/mL solutions in acetone at room temperature by solvent evaporation. The samples were characterized by X-ray powder diffraction, differential scanning calorimetry (DSC), scanning electron microcopy and attenuated total reflectance infrared Fourier transform spectroscopy. Form 1 was nucleated from 40?mg/mL solutions on the six polymers and from 10?mg/mL solutions on PI and NBR. The mixture of form 1 and form 2 was obtained from 10?mg/mL solution on HPMC, dextran and gelatin and from 0.5?mg/mL solution crystallizations. Therefore, the polymeric devices, which crystallized the metastable and more soluble polymorph (2) of progesterone, would be a promissory alternative for the pharmaceutical applications.     

A patient-specific computational model of hypoxia-modulated radiation resistance in glioblastoma using 18F-FMISO-PET

Glioblastoma multiforme (GBM) is a highly invasive primary brain tumour that has poor prognosis despite aggressive treatment. A hallmark of these tumours is diffuse invasion into the surrounding brain, necessitating a multi-modal treatment approach, including surgery, radiation and chemotherapy. We have previously demonstrated the ability of our model to predict radiographic response immediately following radiation therapy in individual GBM patients using a simplified geometry of the brain and theoretical radiation dose. Using only two pre-treatment magnetic resonance imaging scans, we calculate net rates of proliferation and invasion as well as radiation sensitivity for a patient''s disease. Here, we present the application of our clinically targeted modelling approach to a single glioblastoma patient as a demonstration of our method. We apply our model in the full three-dimensional architecture of the brain to quantify the effects of regional resistance to radiation owing to hypoxia in vivo determined by [¹⁸F]-fluoromisonidazole positron emission tomography (FMISO-PET) and the patient-specific three-dimensional radiation treatment plan. Incorporation of hypoxia into our model with FMISO-PET increases the model–data agreement by an order of magnitude. This improvement was robust to our definition of hypoxia or the degree of radiation resistance quantified with the FMISO-PET image and our computational model, respectively. This work demonstrates a useful application of patient-specific modelling in personalized medicine and how mathematical modelling has the potential to unify multi-modality imaging and radiation treatment planning.     

Development of an Active Thermoplastic Film with Oxygen Scavengers Made of Activated Carbon and Sodium Erythorbate

An active thermoplastic film made of low‐density polyethylene (LDPE) filled with oxygen scavengers made of powdered activated carbon (PAC) impregnated with sodium erythorbate (SE) was developed for packaging applications. Initial tests indicated that the impregnation of PAC with SE enhanced the heat resistance of SE, thereby allowing processing at temperatures typical of LDPE manufacturing. Subsequently, LDPE films with PAC/SE particles were manufactured in coupons that represented a typical juice package, and experiments indicated that these films absorbed 3.57 mg of oxygen in 11 days. This amount corresponded to 80% the concentration of oxygen in the headspace of the package. Furthermore, findings indicated that active particles alone have 10 times higher oxygen absorption capacity than the active LDPE film. Finally, the physical properties of the film were characterized by microscopy where oxygen scavengers showed a good dispersion within the matrix. However, 20 wt.% of these active particles decreased tensile strength of the film by 53%. Copyright © 2014 John Wiley & Sons, Ltd.     

Enhancement of the Magnetic Coupling in Exfoliated CrCl3 Crystals Observed by Low-Temperature Magnetic Force Microscopy and X-ray Magnetic Circular Dichroism

Magnetic crystals formed by 2D layers interacting by weak van der Waals forces are currently a hot research topic. When these crystals are thinned to nanometric size, they can manifest strikingly different magnetic behavior compared to the bulk form. This can be the result of, for example, quantum electronic confinement effects, the presence of defects, or pinning of the crystallographic structure in metastable phases induced by the exfoliation process. In this work, an investigation of the magnetism of micromechanically cleaved CrCl₃ flakes with thickness >10 nm is performed. These flakes are characterized by superconducting quantum interference device magnetometry, surface-sensitive X-ray magnetic circular dichroism, and spatially resolved magnetic force microscopy. The results highlight an enhancement of the CrCl₃ antiferromagnetic interlayer interaction that appears to be independent of the flake size when the thickness is tens of nanometers. The estimated exchange field is 9 kOe, representing an increase of ≈900% compared to the one of the bulk crystals. This effect can be attributed to the pinning of the high-temperature monoclinic structure, as recently suggested by polarized Raman spectroscopy investigations in thin (8–35 nm) CrCl₃ flakes.     

A one-step treatment for chondral and osteochondral knee defects: clinical results of a biomimetic scaffold implantation at 2 years of follow-up

The increasing interest in the role of subchondral bone with regard to articular surface disease led to the development of new bioengineered strategies. Aim of this study is to evaluate the clinical and MRI outcome after the implantation of a nanostructured biomimetic three-phasic collagen–hydroxyapatite construct for the treatment of chondral and osteochondral defects of the knee in a large cohort of patients. Seventy-nine patients (63 M, 16 W), affected by grade III–IV femoral condyle or trochlea chondral lesions or osteochondritis dissecans (OCD) were consecutively treated. Mean age was 31.0 ± 11.3 years, mean lesion size was 3.2 ± 2.0 cm². Fifty patients underwent previous surgeries, concurrent procedures were necessary in 39 cases. The clinical outcome was evaluated using the IKDC and Tegner scores at 12 and 24 months of follow-up. At follow-up times an MRI was performed and evaluated with the MOCART score. All the scores improved significantly from the baseline. IKDC subjective score showed a further increase between 12 and 24 months of follow-up, and 82.2 % of the patients improved their symptoms at the final evaluation. Patients affected by OCDs had better results than those with degenerative lesions. Some abnormal MRI findings were present, even though no correlation was found with the clinical outcome. This one-step biomimetic approach developed to favor osteochondral tissue regeneration is effective in treating knees affected by damages of the articular surface, leading to a significant clinical improvement. However, abnormal MRI findings were present, even if not correlated with the clinical outcome.     

A comparative study of zirconium and titanium implants in rat: osseointegration and bone material quality

Permanent metal implants are widely used in human medical treatments and orthopedics, for example as hip joint replacements. They are commonly made of titanium alloys and beyond the optimization of this established material, it is also essential to explore alternative implant materials in view of improved osseointegration. The aim of our study was to characterize the implant performance of zirconium in comparison to titanium implants. Zirconium implants have been characterized in a previous study concerning material properties and surface characteristics in vitro, such as oxide layer thickness and surface roughness. In the present study, we compare bone material quality around zirconium and titanium implants in terms of osseointegration and therefore characterized bone material properties in a rat model using a multi-method approach. We used light and electron microscopy, micro Raman spectroscopy, micro X-ray fluorescence and X-ray scattering techniques to investigate the osseointegration in terms of compositional and structural properties of the newly formed bone. Regarding the mineralization level, the mineral composition, and the alignment and order of the mineral particles, our results show that the maturity of the newly formed bone after 8 weeks of implantation is already very high. In conclusion, the bone material quality obtained for zirconium implants is at least as good as for titanium. It seems that the zirconium implants can be a good candidate for using as permanent metal prosthesis for orthopedic treatments.     

Fracture toughness characterisation of a glass fibre‐reinforced plastic composite

By examining the state of the art, it can be realised that few research works have been done on the fracture behaviour of plastic composites reinforced with continuous glass fibres. Therefore, the present paper deals with the fracture toughness of a unidirectional glass fibre‐reinforced plastic (GFRP), such a parameter being analytically determined by means of the modified two‐parameter model (MTPM). The input data of the MTPM are obtained from an experimental campaign related to three‐point bending tests on single edge‐notched specimens characterised by different sizes. The novelty of this research work is that the MTPM, originally proposed for isotropic materials, is here employed to estimate the fracture toughness of GFRPs characterised by orthotropic mechanical properties.