CLPFFD-PEG functionalized NIR-absorbing hollow gold nanospheres and gold nanorods inhibit β-amyloid aggregation

Gold nanoparticles with specific optical properties in combination with the CLPFFD peptide that exhibits selectivity for β-amyloid (Aβ) aggregates are promising photothermal absorbers for application in Alzheimer's disease therapy. We report on hollow gold nanospheres (HAuNS) and gold nanorods (AuNR), which exhibit strong plasmonic near infrared (NIR) absorbance in the optical window of biological tissue and which are functionalized with CLPFFD in two different ways. Therefore the peptide was either directly bound to the particle surface or indirectly to a particle-protecting polyethylene glycol (PEG) ligand shell, thereby reducing the CLPFFD density on the surfaces of both types of particles. Fully PEGylated particles were used for comparison. The effects on cell viability and the fundamental suitability of the HAuNS and AuNR conjugates as photothermal absorbers to inhibit Aβ-fibrillation are analysed in vitro. The positive influence of the use of PEG ligands on the reduced cytotoxicity of the conjugates and on the Aβ-disaggregation is discussed.

Ion specific effects on the immobilisation of charged gold nanoparticles on metal surfaces

Since the pioneering work of F. Hofmeister, Arch. Exp. Pathol. Pharmakol., 1888, 24, 247, ion specific effects have been steadily reported in the context of colloidal or protein stabilisation in electrolyte solutions. Although the observed effects are omnipresent in chemistry and biology, their origin is still under ferocious discussion. Here, we report on ion specific effects affecting the self-assembly of amine and carboxylic acid functionalised gold nanoparticles on metal surfaces as well as in electrolyte solution as a function of the monovalent cations Li⁺, Na⁺, K⁺ and Cs⁺. Mercaptooctanoic acid and 1,8-amine-octanethiol functionalised gold nanoparticles were adsorbed on structured AuPd/Pt substrates under addition of the respective chloride salts. Furthermore, the influence of the same salts on the salt induced aggregation of these AuNP was investigated. Our results demonstrate that the assembly processes on the metal surface as well as in electrolyte solution are influenced by the addition of different cations. We attribute the observed effects to ion pairing of the functional end groups with the added cations. With these findings we introduce a new parameter to control the self-assembly of 2D AuNP arrays on solid supports or of 3D AuNP networks in solution, which could be of relevance for the fabrication of new tailor-made functional materials or for biomedical applications.

Different monovalent cations influence the immobilisation of carboxylic acid and amine terminated gold nanoparticles.

Gold nanoparticles stabilized with βcyclodextrin-2-amino-4-(4-chlorophenyl)thiazole complex: A novel system for drug transport

While 2-amino-4-(4-chlorophenyl)thiazole (AT) drug and thiazole derivatives have several biological applications, these compounds present some drawbacks, such as low aqueous solubility and instability. A new complex of βCD-AT has been synthesized to increase AT solubility and has been used as a substrate for the deposit of solid-state AuNPs via magnetron sputtering, thus forming the βCD-AT-AuNPs ternary system, which is stable in solution. Complex formation has been confirmed through powder X-ray diffraction and 1D and 2D nuclear magnetic resonance. Importantly, the amine and sulfide groups of AT remained exposed and can interact with the surfaces of the AuNPs. The complex association constant (970 M^-1) has been determined using phase solubility analysis. AuNPs formation (32 nm average diameter) has been studied by UV-Visible spectroscopy, transmission/scanning electron microscopy and energy-dispersive X-ray analysis. The in vitro permeability assays show that effective permeability of AT increased using βCD. In contrast, the ternary system did not have the capacity to diffuse through the membrane. Nevertheless, the antibacterial assays have demonstrated that AT is transferred from βCD-AT-AuNPs, being available to exert its antibacterial activity. In conclusion, this novel βCD-AT-AuNPs ternary system is a promising alternative to improve the delivery of AT drugs in therapy.

Hydrophobic superparamagnetic FePt nanoparticles in hydrophilic poly(N-vinylcaprolactam) microgels: a new multifunctional hybrid system

We report the synthesis of a new multifunctional colloidal hybrid system consisting of thermoresponsive amphiphilic biocompatible poly(N-vinylcaprolactam) microgels loaded with hydrophobic superparamagnetic FePt nanoparticles (NPs).

Surface coupling strength of gold nanoparticles affects cytotoxicity towards neurons

Weakly bound gold nanoparticles reveal awful toxicity towards neurons.

Multivalency of PEG-thiol ligands affects the stability of NIR-absorbing hollow gold nanospheres and gold nanorods

In this work the effect of multivalency on the stability of NIR-absorbing HAuNSs and AuNRs functionalized by mono-, bi- and tridentate polyethyleneglycol (PEG) thiol ligands is reported.

The Müller acetabular reinforcement ring--still an option in acetabular revision of Paprosky 2 defects? Longterm results after 10 years

BACKGROUND

Aim of this study was to measure the clinical and radiological longterm outcome after acetabular revision arthroplasty (RTHA) using the Müller acetabular reinforcement ring.

MATERIAL AND METHODS

86 patients with 90 revision arthroplasties and a mean age of 68 years (41 to 84) were included. The mean follow-up was 10 years (range 7-12). The Harris Hip Score and the WOMAC Index were used to assess pain and functional outcome. Furthermore clinical examination of range of motion and radiologic examinations were performed in 34 patients.

RESULTS

The radiologic analysis reports no signs of loosening in 79%, 15% showed possibly loosening and 6% probable loosening. Definite radiologic loosening has not been detected. In the meantime 12 patients (13.3%) of 90 revision total hip arthroplasty underwent a revision of the acetabulum with change of the acetabular component which means a survival rate of 86.7% after 10 years follow-up. The mean center of rotation of the hip moved 0.15 cm (SD 0.74 cm) laterally and 0.1 cm (SD 0.97 cm) cranially based on the geometrically reconstructed center of rotation. A mean score of 58 points for the Harris Hip Score (range 14-93) indicated a poor functional outcome, while a mean value of 96 points (range 0-223) for the WOMAC Index indicated good results for functional outcome in daily living.

CONCLUSIONS

The revision arthroplasty in cases with acetabular defects using the Müller acetabular reinforcement ring shows acceptable longterm results.

LEVEL OF EVIDENCE

Level IV.

Feasibility study of the Mn–Na2WO4/SiO2 catalytic system for the oxidative coupling of methane in a fluidized-bed reactor

The catalytic system Mn–Na₂WO₄/SiO₂, was studied in a miniplant fluidized-bed reactor for oxidative coupling of methane.

Polydiacetylene stabilized gold nanoparticles – extraordinary high stability and integration into a nanoelectrode device

A new diacetylene containing photopolymerizable ligand molecule was developed, and tailored for applications in nanoelectronic devices based on gold nanoparticles.

Enhanced catalytic performance of MnxOy–Na2WO4/SiO2 for the oxidative coupling of methane using an ordered mesoporous silica support

The oxidative coupling of methane is a highly promising reaction for its direct conversion.

Preferential adhesion of silver nanoparticles onto crystal faces of alpha-cyclodextrin/carboxylic acids inclusion compounds

Alpha-Cyclodextrin (alpha-CD) inclusion compounds containing the carboxylic acids (octanoic, decanoic, lauric or dodecanoic, myristic or tetradecanoic, palmitic or hexadecanoic and stearic or octadecanoic) as guests were synthesized and applied for preferential adhesion of silver nanoparticles (AgNPs). The binding affinity depends of the chain length of the respective guest and is most efficient for octanoic and decanoic acids. The immobilization of nanoparticles is caused by the spatial replacing of the stabilized shell of the nanoparticles by COOH groups of the guests molecules, located at the entrance of cavity of alpha-CD, corresponding to the {001} crystal plane. Crystalline coating with nanoparticles provides a means of storing of AgNPs on solids state without aggregation. The stabilization of the particles on the surface is valid for a given length and ordering of the guest in the cavities of the alpha-CD being the octanoic and decanoic acid the most appropriated.

Patterned self-assembly of gold nanoparticles on chemical templates fabricated by soft UV nanoimprint lithography

Chemical templates for the patterned immobilization of gold nanoparticles were fabricated by soft UV nanoimprint lithography. The template structures were fabricated by means of the consecutively performed process steps of nanoimprint lithography, reactive ion etching, chemical functionalization with amino groups, and lift-off of imprint resist. These chemical templates were used for the defined assembly of 20 nm diameter citrate stabilized gold nanoparticles from aqueous solution. By reducing the ionic strength of the solution, one- and zero-dimensional particle assemblies were generated on sub-100-nm template structures. By this means, the pattern resolution predefined by the lithography process could be easily enhanced by dilution of the nanoparticle solution.

Electronic Properties of Compact and Diluted Metal-Clusters by Impedance Spectroscopy

All presently published electrical and optical measurements on concentrated ligand stabilized Au55-cluster samples reveal an inter-cluster tunnel-conductivity and indicate the influence of a “quantum-size-effect” (QSE) [1],[2]. However these data do not show any initials for the separation of inter- and possible intracluster effects. In the present Raper electronic intra-cluster Properties such as the electrical “conductivity” of 1nm chemical auantum dots, their relaxation frequencies and the relevant activation enthalpies as well as the respective Properties of pairs of Au55-clusters have been investigated in comparison to diluted clusters and interpreted by means of Impedance Spectroscopy. Furthermore a method to determine the number and the density of states (DOS) in the metal-core from the measuring data by means of very simple quantum-size assumptions is presented, which is compatible with both the SIMIT[3] and the existing cluster models.

[Cementless femoral neck prosthesis CUT--clinical and radiological results after 5 years]

AIM

With regard to total replacement of the hip, revision arthroplasty poses a challenge especially for younger patients. In spite of substantial improvements, new materials and operation techniques are still not able to prevent a shorter running life of prostheses in this group. The present work aims at evaluating clinical and radiological mid-term results of the femoral neck prosthesis CUT (ESKA Orthodynamics Lübeck) to answer the question of whether this implant is recommendable for younger patients.

METHOD

Between 2001 and 2005 a consecutive series of 99 CUT prostheses was performed in 86 patients (50 female, 36 male) with a mean age of 50 (17-72) years and again evaluated clinically and radiologically after 5.4 (1.7-6.5) years. 84 cases were operated using a posterior approach and 15 cases were operated according to the anterolateral Watson-Jones approach. For clinical evaluation the Harris hip score and the visual analogue scale (VAS) for pain measurement were applied. Standard anteroposterior radiographs of the pelvis and lateral radiographs of the operated hip were compared to radiographs taken in the recovery room by two independent observers. Interobserver measurement discrepancy of the implant angle was 2.6 +/- 1.4 degrees. With 4 degrees being the maximum discrepancy, it was defined as the threshold of the normal range of 145 degrees (141-149 degrees). Additionally, the amount of femoral neck resection, the contact of the medial corticalis with the proximal stem, and the contact of the lateral corticalis with the distal part of the stem, periarticular ossifications and stable fixation by bone ingrowth according to Engh et al. were evaluated. Five delineated sections around the femoral component for evaluation of looseness or progressive loosening were used according to Gruen et al. Radiological evaluation of the cup was performed according to Charnley and DeLee.

RESULTS

The survival rate according to Kaplan-Meier was 98 % after on average 6.6 years. The Harris hip score significantly improved from 50 (16-83) points preoperatively to 98 (40-100) points at the time of follow-up (p < or = 0.05). 82 % achieved an excellent result (91-100 points), 10% a good (91-90 points), 4% had a moderate (71-80 points) and 4% had a bad (< 70 points) result. Six prostheses had to be revised. One of them had to be changed to a cementless standard stem after 5 years because of aseptic loosening. Another one had to be revised after 2.7 years because of chronic thigh pain. Two painful hips had a capsular revision. In one case the liner had to be changed and one case had an exchange of the femoral ball for a better femoral offset. The VAS revealed a significant reduction of pain in rest and under load (p < or = 0.05). 92% had a correct subcapital neck resection. The recommended implant angle of 145 degrees was seen in 72% while a valgus alignment in 18% and a varus alignment in 10% was measured. Undersizing of the CUT-prosthesis was seen in 27 cases. Nine of these cases developed a varus alignment. Osseous integration of the cup and stem was seen in 100% and in 95%, respectively.

CONCLUSION

This study demonstrates the CUT prosthesis as a bone-preserving prosthesis with good functional and radiological results and therefore as an alternative joint replacement in younger patients.

Simulation of the nutrient supply in fracture healing

The healing process for bone fractures is sensitive to mechanical stability and blood supply at the fracture site. Most currently available mechanobiological algorithms of bone healing are based solely on mechanical stimuli, while the explicit analysis of revascularization and its influences on the healing process have not been thoroughly investigated in the literature. In this paper, revascularization was described by two separate processes: angiogenesis and nutrition supply. The mathematical models for angiogenesis and nutrition supply have been proposed and integrated into an existing fuzzy algorithm of fracture healing. The computational algorithm of fracture healing, consisting of stress analysis, analyses of angiogenesis and nutrient supply, and tissue differentiation, has been tested on and compared with animal experimental results published previously. The simulation results showed that, for a small and medium-sized fracture gap, the nutrient supply is sufficient for bone healing, for a large fracture gap, non-union may be induced either by deficient nutrient supply or inadequate mechanical conditions. The comparisons with experimental results demonstrated that the improved computational algorithm is able to simulate a broad spectrum of fracture healing cases and to predict and explain delayed unions and non-union induced by large gap sizes and different mechanical conditions. The new algorithm will allow the simulation of more realistic clinical fracture healing cases with various fracture gaps and geometries and may be helpful to optimise implants and methods for fracture fixation.

Face preferred deposition of gold nanoparticles on α-cyclodextrin/octanethiol inclusion compound

The preferred deposition of gold nanoparticles (Au NPs) onto microcrystal faces of alpha-cyclodextin/octanethiol inclusion compound was obtained. The immobilization of Au NPs is caused by the spatial replacing of the citrate shell of the NPs by the free dangling SH groups of the guest molecule.

High-Throughput Gas Sensing Screening of Surface-Doped In2O3

The effect of various surface doping elements on the electrical and gas sensing properties of indium(III) oxide thick films sensors was investigated by means of high-throughput impedance spectroscopy (HTIS). Some doping elements lead to changes in both the conductivity in air as well as in the gas sensing properties towards oxidizing (NO(2), NO) and reducing (H(2), CO, propene) gases. Correlations between the sensing and the electrical properties in reference atmosphere indicate that the effect of the doping elements can be ascribed to an influence on the oxidation state of the metal oxide surface rather that to an interaction with the respective testing gases. An equation for the description of the temperature-dependent conductivity in air and nitrogen is proposed to describe the oxidation state of the metal oxide surface taking into account sorption of oxygen. Furthermore, a model associating the sensing properties and the oxidation state of the surface layer of the metal oxide based on oxygen spillover from doping element particles to the metal oxide surface is introduced.

Patient information on cognitive symptoms in multiple sclerosis - acceptability in relation to disease duration

OBJECTIVE

Recently, regular cognitive screening assessments have been advised in multiple sclerosis (MS). No studies have been carried out yet on the acceptability of information on cognitive deficits among MS patients.

MATERIALS AND METHODS

Translation of an information booklet developed by a working group of European MS Rehabilitation Centers. Distribution of the booklet among 133 MS patients of two rehabilitation units and one outpatient clinic together with a one-page questionnaire.

RESULTS

The booklet was highly understandable and rated to give moderate new information. Overall, the brochure was perceived as encouraging but significantly less so (P = 0.014) in recently diagnosed patients. Patients with subjectively perceived deficits considered the brochure to be significantly more relevant (P = 0.002).

CONCLUSION

Information on cognitive deficits does not increase fears even in recently diagnosed MS patients. Patients with perceived deficits found the information more relevant than others and also less familiar. Thus, it seems appropriate to offer information about cognitive impairments to MS patients.

Setup for High-Throughput Impedance Screening of Gas-Sensing Materials

This paper reports on the setup for a high-throughput impedance measurement system that allows rapid screening of the electrical and dielectrical properties of solid-state sample libraries in variable atmospheres and temperatures. Using multielectrode arrays, most time-consuming steps in the workflow are parallelized. In addition, an approach for automated data evaluation of impedance spectra is presented. For reasons of verification of robust measuring results and reproducibility, screening results of a sample library composed of doped indium(III) oxide as a resistive-type gas-sensing material are discussed on the basis of the determined sensitivities focusing temperature and testing gas gradients.

Gold nanoparticles: assembly and electrical properties in 1–3 dimensions

Ligand stabilized gold nanoparticles have attracted much attention in the search for new chemically designed compounds for a future information technology, based on single-electron devices. This article gives an overview about the strategies used to synthesize and to assemble uniform gold nanoparticles in different dimensions as well as about the present status of the electrical properties of these. Examples are given for three-dimensional organisations, for the formation of self-assembled monolayers as well as for one-dimensional assemblies.

A new acceleration apparatus for the study of whiplash with human cadaveric cervical spine specimens

The biomechanics of whiplash is often studied using cadaveric cervical spine specimens. One of the most important points in this kind of study is to create realistic loading conditions. The aim of the present project therefore was to develop an acceleration apparatus, which allows the study of whiplash with human cadaveric cervical spine specimens under as realistic loading conditions as possible. The new acceleration apparatus mainly consisted of a sled, a pneumatic acceleration unit and a railtrack and offered several unique features to create more realistic loading conditions. Among these features, the possibility to simulate the passive movements of the trunk is of capital importance. In this new apparatus, first, the general feasibility of whiplash experiments was studied, second, the reproducibility of the impacts was quantified and third, the effect of simulated movements of the trunk on accelerations and loads was examined. In the new acceleration apparatus various types of collisions could reproducibly be simulated. Simulated passive movements of the trunk strongly influenced the loading pattern of the neck. Without pivoting a steep increase of all loading parameters could be observed. This increase was less pronounced if pivoting was allowed. In conclusion, biomechanical aspects of whiplash could reproducibly be examined in the new acceleration apparatus. Due to its significant effects on the loading of the neck, pivoting of the trunk should always be taken into account in future experiments on the biomechanics of whiplash in which isolated cervical spine specimens are used.

Preserving the abductor mechanism in robotic THR: the influence of stem design and cutterpath

OBJECTIVE

The tip of the greater trochanter is the attachment site for the abductor muscles of the hip joint. Its preservation in robotic and conventional THR is important for normal gait. The effect of different stem designs and robotic cutterpaths on the preservation of the trochanter tip is examined.

MATERIALS AND METHODS

One anatomical stem, one straight stem, and one stem specifically designed for robotic THR were implanted virtually in CT scans of osteoarthrotic hip joints using the Torch preoperative planning unit (URS-ortho). In transverse sections of the trochanter tip, dimensions of the trochanter area removed by the milling tool were recorded for each stem design and different cutterpaths (3-axis versus 5-axis milling).

RESULTS

Five-axis milling showed significantly better results than 3-axis milling. For straight stems, more bone was removed than for anatomic stems. The most favorable results were achieved with 5-axis milling and a curved stem specifically designed for robotic THR.

CONCLUSIONS

The introduction of 5-axis milling in robotic THR is an improvement of the technique and makes preservation of the abductor mechanism at the tip of the greater trochanter easier for the surgeon.

Extension of a state-of-the-art optimization criterion to predict co-contraction

Most studies concerned with the prediction of muscle forces have tried to predict a physiologically reasonable, synergistic muscle behavior. In addition to the load sharing of synergistic muscles, co-contraction of antagonistic muscles also occurs. An extension to a standard quadratic criterion for the calculation of muscle forces is presented in this study. This extension however is not limited to quadratic optimization. The extension is applied to a planar, one degree of freedom model of the human knee. For this model an analytical solution is presented. With the extended criterion it was possible to predict and control the amount of co-contraction for the knee model. The enforced antagonistic muscle activity led to higher agonistic muscle activity. In the absence of an external load flexor and extensor muscles were activated. As a consequence the knee joint was preloaded. This might indicate that antagonistic muscle activity is generated to maintain or improve joint stability. In conclusion, this study presents a novel approach to predict co-contraction when using optimization techniques to determine muscle forces by introducing a shift parameter for the optimization criterion.

Influence of the stiffness of bone defect implants on the mechanical conditions at the interface--a finite element analysis with contact

The study focused on the influence of the implant material stiffness on stress distribution and micromotion at the interface of bone defect implants. We hypothesized that a low-stiffness implant with a modulus closer to that of the surrounding trabecular bone would yield a more homogeneous stress distribution and less micromotion at the interface with the bony bed. To prove this hypothesis we generated a three-dimensional, non-linear, anisotropic finite element (FE) model. The FE model corresponded to a previously developed animal model in sheep. A prismatic implant filled a standardized defect in the load-bearing area of the trabecular bone beneath the tibial plateau. The interface was described by face-to-face contact elements, which allow press fits, friction, sliding, and gapping. We assumed a physiological load condition and calculated contact pressures, shear stresses, and shear movements at the interface for two implants of different stiffness (titanium: E=110GPa; composite: E=2.2GPa). The FE model showed that the stress distribution was more homogeneous for the low-stiffness implant. The maximum pressure for the composite implant (2.1 MPa) was lower than for the titanium implant (5.6 MPa). Contrary to our hypothesis, we found more micromotion for the composite (up to 6 microm) than for the titanium implant (up to 4.5 microm). However, for both implants peak stresses and micromotion were in a range that predicts adequate conditions for the osseointegration. This was confirmed by the histological results from the animal studies.

1K versus 2K monitor: a clinical alternative free-response receiver operating characteristic study of observer performance using pulmonary nodules

OBJECTIVE

The aim of this study was to investigate whether and how observer performance in detecting pulmonary nodules is influenced by the use of 1K and 2K monitors with and without voluntary postprocessing.

MATERIALS AND METHODS

The study was conducted with clinical digital chest radiographs of 48 patients. CT images of the same patient group served as the gold standard. Data on four different monitor conditions (1K overview, 2K overview, 1K with postprocessing, and 2K with postprocessing) were collected using a 6-point confidence-rating scale and interpreted with an alternative free-response receiver operating characteristic.

RESULTS

When magnification and window settings were applied on the 1K monitor at the expense of an increased interpretation time, observer performance with the 1K monitor was not significantly different from that with the 2K monitor. A significant difference only occurred between the 1K monitor postprocessing condition and the 1K monitor overview condition.

CONCLUSION

Considering diagnostic accuracy, the 1K monitor is sufficient for the detection of pulmonary nodules, provided that postprocessing options--especially magnification--are applied. Further comparative monitor studies on the detectability of other abnormalities (e.g., fine interstitial structures) need to be performed.

Dispersion pre-compensation of 15 femtosecond optical pulses for high-numerical-aperture objectives

The excitation efficiency in two-photon absorption (TPA) microscopy depends strongly - owing to the square dependence of the TPA fluorescence on the excitation intensity - on the temporal width of the excitation pulse. Because of their inherently large frequency bandwidth, ultrashort optical pulses tend to broaden substantially because of dispersion from propagation through the dispersive elements in the microscope. In this paper, the dispersion characteristics of a wide range of microscope objectives are investigated. It is shown that the induced dispersion can be pre-compensated in all cases for pulses as short as 15 fs. Because of the excellent agreement between the results from theoretical modelling and the experimental data, predictions of the possibility of dispersion control for microscope objectives in general, as well as for even shorter pulses, can be inferred. Since for TPA imaging the background due to single photon absorption processes and scattering is independent of the pulse width, proper dispersion pre-compensation - which minimizes the pulse duration at the focal point and hence maximizes the excitation efficiency - provides optimal image contrast in TPA microscopy.