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Four years after its first report, expansion microscopy (ExM) is now being routinely applied in laboratories worldwide to achieve super-resolution imaging on conventional fluorescence microscopes. By chemically anchoring all molecules of interest to the polymer meshwork of an expandable hydrogel, their physical distance is increased by a factor of ∼4-5× upon dialysis in water, resulting in an imprint of the original sample with a lateral resolution up to 50-70 nm. To ensure a correct representation of the original spatial distribution of the molecules, it is crucial to confirm that the expansion is isotropic, preferentially in all three dimensions. To address this, we present an approach to evaluate the local expansion factor within a biological sample and in all three dimensions. We use photobleaching to introduce well-defined three-dimensional (3D) features in the cell and, by comparing the size and shape pre- and postexpansion, these features can be used as an intrinsic ruler. In addition, our method is capable of pointing out sample distortions and can be used as a quality control tool for expansion microscopy experiments in biological samples. ispartof: ACS OMEGA vol:5 issue:12 pages:6792-6799 ispartof: location:United States status: published

The development of novel molecular sieves opens opportunities in the development of more sensitive analytical devices. In this paper, metal organic frameworks (MOFs), specifically ZIF-8 and ZIF-93, are grown on fiber optic based surface plasmon resonance (FO-SPR) sensors. FO-SPR has enabled sensitive sensing capabilities in biomedical settings and the addition of an MOF coating opens the way for the sensing of volatile organic compounds (VOCs) in gaseous media. FO-SPR probes were homogeneously functionalized with ZIF-8 and ZIF-93 in each case using two different precursor solutions to obtain a sequential nucleation and growth phase. The difference in MOF nucleation and growth kinetics of the two solutions was directly monitored by the FO-SPR system. The two established MOF-FO-SPR sensors were then subjected to sensing experiments with several alcohol vapors to establish their sensing capabilities. Vapors with mPa partial pressures, ppm concentrations, could successfully be detected, e.g., an LOD of 2.5 ppm for methanol detection was acquired. The difference in recognition behavior of the hydrophobic ZIF-8 and more hydrophilic ZIF-93 recognition layers can be exploited to yield qualitative information regarding the vapor composition.

A highly reproducible and controllable deposition procedure for gold nanostructures on a titanium dioxide (TiO2) surface using femtosecond laser light has been demonstrated. This is realized by precisely focusing onto the TiO2 surface in the presence of a pure gold ion solution. The deposition is demonstrated both in dot arrays and line structures. Thanks to the multi-photon excitation, we observe that the deposition area of the nanostructures can be confined to a degree far greater than the diffraction limited focal spot. Finally, we demonstrate that catalytic activity with visible light irradiation is enhanced, proving the applicability of our new deposition technique to the catalytic field. ispartof: Nanoscale vol:9 issue:35 pages:13025-13033 ispartof: location:England status: published

Photocatalytic reactions occur at the crystal-solution interface, and hence specific crystal facet expression and surface defects can play an important role. Here we investigate the structure-related photoreduction at zinc oxide (ZnO) microparticles via integrated light and electron microscopy in combination with silver metal photodeposition. This enables a direct visualization of the photoreduction activity at specific crystallographic features. It is found that silver nanoparticle photodeposition on dumbbell-shaped crystals mainly takes place at the edges of O-terminated (0001̅) polar facets. In contrast, on ZnO microrods photodeposition is more homogeneously distributed with an increased activity at {101̅1̅} facets. Additional time-resolved measurements reveal a direct spatial link between the enhanced photoactivity and increased charge carrier lifetimes. These findings contradict previous observations based on indirect, bulk-scale experiments, assigning the highest photocatalytic activity to polar facets. The presented research demonstrates the need for advanced microscopy techniques to directly probe the location of photocatalytic activity. ispartof: JOURNAL OF PHYSICAL CHEMISTRY LETTERS vol:8 issue:2 pages:340-346 ispartof: location:United States status: published

© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim An integrated optical-electron microscope is presented that enables the in situ study of dynamic processes on photoactive materials. Here, the deposition of metallic silver nanostructures at ZnO photocatalyst particles is monitored in real time under ambient conditions by means of scanning electron microscopy. Zinc oxide crystals are immobilized on an electron transparent silicon nitride window. By passing UV light through an opposing optically transparent window, the zinc oxide is illuminated resulting in the photocatalytic formation of silver nanostructures. Both windows are part of a specially designed liquid cell filled with a dilute aqueous silver nitrate solution. Using the presented system, different electron detectors are evaluated for their ability to provide detailed images despite the interference caused by the liquid surrounding the sample. Special care has to be taken since direct silver reduction from solution induced by the electron beam interferes with the photocatalytic process. Oxygen gas, produced during the photocatalytic reaction, is also shown to complicate the imaging of the dynamic nanoscale processes in the scanning electron microscope. Nevertheless, the integrated approach allows to directly establish structure–activity relationships and to unravel optically induced processes at nanostructured materials. ispartof: PARTICLE & PARTICLE SYSTEMS CHARACTERIZATION vol:33 issue:7 pages:412-418 status: published

Optical microscopy has been a tool of choice ever since van Leeuwenhoek used Hooke's microscope to observe biological specimens. Chief among its advantages is the fact that imaging is noninvasive. In combination with the straightforward sample preparation and general convenience, optical microscopes remain essential to many aspects of modern-day research.

The performance of zeolites as solid acid catalysts is strongly influenced by the accessibility of active sites. However, synthetic zeolites typically grow as complex aggregates of small nanocrystallites rather than perfect single crystals. The structural complexity must therefore play a decisive role in zeolite catalyst applicability. Traditional tools for the characterization of heterogeneous catalysts are unable to directly relate nanometer scale structural properties to the corresponding catalytic performance. In this work, an innovative correlative super-resolution fluorescence and scanning electron microscope is applied and the appropriate analysis procedures are developed to investigate the effect of small-port H-mordenite (H-MOR) morphology on the catalytic performance, along with the effects of extensive acid leaching. These correlative measurements revealed catalytic activity at the interface between intergrown H-MOR crystallites that was assumed inaccessible, without compromising the shape selective properties. Furthermore, it was found that extensive acid leaching led to an etching of the originally accessible microporous structure, rather than the formation of an extended mesoporous structure. The associated transition of small-port to large-port H-MOR therefore did not render the full catalyst particle functional for catalysis. The applied characterization technique allows a straightforward investigation of the zeolite structure-activity relationship beyond the single-particle level. We conclude that such information will ultimately lead to an accurate understanding of the relationship between the bulk scale catalyst behavior and the nanoscale structural features, enabling a rationalization of catalyst design. ispartof: ACS Catalysis vol:7 issue:8 pages:5234-5242 ispartof: location:United States status: published

Please cite this paper as: Janssen P, Brolmann H, van Kesteren P, Bongers M, Thurkow A, Heymans M, Huirne J. Perioperative outcomes using LigaSure compared with conventional bipolar instruments in laparoscopic hysterectomy: a randomised controlled trial. BJOG 2011;118:1568–1575. Objective To compare the effects of LigaSure versus the conventional bipolar technique on operating time and blood loss during laparoscopic hysterectomy. Design A randomised controlled trial. Setting Three teaching hospitals. Population Women undergoing a laparoscopic hysterectomy for benign indications. Methods 140 women undergoing a laparoscopic hysterectomy were randomised for LigaSure or conventional bipolar instruments. Main outcome measures Primary outcome was operating time from initial skin incision till detachment of the uterus. Secondary outcome measures were total operating time (from initial skin incision till final skin closure), time to dissect the adnexal ligaments, intra-operative blood loss and subjective evaluation by the surgeon of the instrument used. Results No differences in operating time (from initial skin incision till uterine detachment and initial skin incision till final skin closure) using LigaSure versus conventional bipolar instruments: 97.6 versus 91.8 minutes (P = 0.39, 95% CI – 7.6 to 19.2), and 148.1 versus 142.1 minutes (P = 0.46, 95% CI – 10.1 to 22.3), respectively. The mean blood loss using LigaSure versus conventional bipolar was 234.1 versus 273.1 ml (P = 0.46, 95% CI -39.1 to 52.7). Various subjective efficacy and instrument handling parameters were significantly different between the two instruments and between the different participating centres. Conclusions There were no significant differences in operating time and blood loss between the use of LigaSure and the use of conventional bipolar instruments during laparoscopic hysterectomy, even after correction for potential confounders. User satisfaction parameters were assessed as significantly different by surgeons of the participating centres.

The cationic dyes 9-aminoacridine (9AA) and safranine (Sf) were entrapped into silica spheres of about 0.2 μm diameter prepared by modified Stober method. The fluorescent materials are investigated by steady-state and time-resolved emission, in addition of confocal fluorescence microscopy. Silica particles containing 9-aminoacridine (SP9AA) and safranine (SPSf) or both dyes (SPSf9AA) are emissive particles. When both dyes are present in the same particle but loaded in sequential stages 9AA emission is quenched as a consequence of energy transfer from 9AA (donor) to Sf (acceptor). This result suggests that particle growing processes where the acceptor is incorporated first into the core do not prevent donor/acceptor pairs to be close due to an overlay of the concentration gradients of both dyes in a radial core-shell like distribution.

This paper is the first report of a fiber optic SPR biosensor with nanobead signal enhancement. We evaluated the system with a bioassay for the fast and accurate detection of peanut allergens in complex food matrices. Three approaches of an immunoassay to detect Ara h1 peanut allergens in chocolate candy bars were compared; a label-free assay, a secondary antibody sandwich assay and a nanobead enhanced assay. Although label-free detection is the most convenient, our results illustrate that functionalized nanobeads can offer a refined solution to improve the fiber SPR detection limit. By applying magnetite nanoparticles as a secondary label, the detection limit of the SPR bioassay for Ara h1 was improved by two orders of magnitude from 9 to 0.09 μg/mL. The super paramagnetic character of the nanoparticles ensured easy handling. The SPR fibers could be regenerated easily and one fiber could be reused for up to 35 times without loss of sensitivity. The results were benchmarked against a commercially available polyclonal ELISA kit. An excellent correlation was found between the Ara h1 concentrations obtained with the ELISA and the concentrations measured with the SPR fiber assay. In addition, with the SPR fiber we could measure the samples twice as fast as compared to the fastest ELISA protocol. Since the dipstick fiber has no need for microchannels that can become clogged, time consuming rinsing step could be avoided. The linear dynamic range of the presented sensor was between 0.1 and 2 μg/mL, which is considerably larger than the ELISA benchmark.

Organometal halide perovskites show promising features for cost-effective application in photovoltaics. The material instability remains a major obstacle to broad application because of the poorly understood degradation pathways. Here, we apply simultaneous luminescence and electron microscopy on perovskites for the first time, allowing us to monitor in situ morphology evolution and optical properties upon perovskite degradation. Interestingly, morphology, photoluminescence (PL), and cathodoluminescence of perovskite samples evolve differently upon degradation driven by electron beam (e-beam) or by light. A transversal electric current generated by a scanning electron beam leads to dramatic changes in PL and tunes the energy band gaps continuously alongside film thinning. In contrast, light-induced degradation results in material decomposition to scattered particles and shows little PL spectral shifts. The differences in degradation can be ascribed to different electric currents that drive ion migration. Moreover, solution-processed perovskite cuboids show heterogeneity in stability which is likely related to crystallinity and morphology. Our results reveal the essential role of ion migration in perovskite degradation and provide potential avenues to rationally enhance the stability of perovskite materials by reducing ion migration while improving morphology and crystallinity. It is worth noting that even moderate e-beam currents (86 pA) and acceleration voltages (10 kV) readily induce significant perovskite degradation and alter their optical properties. Therefore, attention has to be paid while characterizing such materials using scanning electron microscopy or transmission electron microscopy techniques. ispartof: Journal of Physical Chemistry Letters vol:7 issue:3 pages:561-566 ispartof: location:United States status: published

Supported metal nanoparticle catalysts are commonly obtained through deposition of metal precursors onto the support using incipient wetness impregnation. Typically, empirical relations between metal nanoparticle structure and catalytic performance are inferred from ensemble averaged data in combination with high-resolution electron microscopy. This approach clearly underestimates the importance of heterogeneities present in a supported metal catalyst batch. Here we show for the first time how incipient wetness impregnation leads to 10-fold variations in silver loading between individual submillimeter-sized silica support granules. This heterogeneity has a profound impact on the catalytic performance, with 100-fold variations in hydrogenation performance at the same level. In a straightforward fashion, optical microscopy interlinks single support particle level catalytic measurements to structural and compositional information. These detailed correlations reveal the optimal silver loading. A thorough consideration of catalyst heterogeneity and the impact thereof on the catalytic performance is indispensable in the development of catalysts. ispartof: ACS Catalysis vol:5 issue:11 pages:6690-6695 ispartof: location:United States status: published

Detection of allergens and micro bacteria on a fiber optic SPR sensor is performed by means of an oligonucleotide bio-recognition surface. In this work, the DNA surface is optimized by mixing with PEG monolayers to suppress unspecific and enhance specific detection. Furthermore, due to the surface characteristic of DNA functionalized gold nanoparticles the bioassay sensitivity is increased and a mean of real-time multiplexing is introduced.

Aptamers are short, single stranded DNA/RNA oligonucleotides with the ability to fold into well-defined three-dimensional structures, which are fundamental for their highly selective target recognition, rivaling thus antibodies in terms of affinity and specificity. Thanks to these properties, they have been integrated into different micro- and nanoscale transducers, resulting in a new type of biosensors, known as `aptasensors', used in a truly new generation of diagnostic tools. Here, an overview will be given of different aptamer selection approaches, with the focus on lab-on-a-chip technology based methods, different concepts reported for integrating aptamers into micro- and nanobiosystems aiming at the development of sensitive diagnostics concluding with an outlook on the future of aptamers in theranostics.

8 ] More recently, PCR related research has advanced to include solid-phase PCR (SP-PCR) because it holds sig-nifi cant promise for applications in high-throughput DNA sequencing and large-scale single-nucleotide polymorphism analysis, circumventing some of the short-comings of con-ventional PCR in these applications. In spite of its poten-tial, SP-PCR is often hampered by relatively low yields of amplicon and subsequent low effi ciencies that are seen in a typical reaction.

Nowadays, an increasing number of minimal invasive treatment alternatives to hysterectomy may be offered to the patient. In determining the appropriate treatment option, the patient has a distinct dilemma if a minimal invasive treatment with lesser effect than hysterectomy should be chosen or if a hysterectomy should be chosen which is a major surgery and requires longer recovery than the minimal invasive alternative. Quality-of-life (QoL) questionnaires that take subjective health perception into account are currently used to assess the treatment effects. The objective of this literature study is to determine and discuss the role of QoL as an outcome in randomized controlled trials (RCT) or systematic reviews of RCTs that study the treatment effect of hysterectomy compared to that of minimal invasive alternatives. A systematic literature search was performed in the PubMed database and in the Cochrane database to find randomized trials and systematic reviews of randomized trials, comparing hysterectomy with minimal invasive or conservative treatment options with sufficient follow-up using satisfaction, health status, and quality of life as outcomes. The results were based on nine randomized trials and two systematic reviews. The differences are mostly in favor of hysterectomy. In two out of four studied treatment alternatives, the satisfaction or health status is different in favor of hysterectomy while the QoL is equivalent. After 2 years of follow-up, differences between both groups have disappeared, possibly because of the crossover effect. Possible reasons for the lesser response of QoL compared to satisfaction or health status are discussed. The fundamental question if patients have a better quality of life at all times if they choose for a minimal invasive alternative of hysterectomy remains unresolved. Information, individualization, and freedom of choice before surgery probably best serve the sense of well being and quality of life thereafter.

Significant research efforts are continually being directed towards the development of sensitive and accurate surface plasmon resonance biosensors for sequence specific DNA detection. These sensors hold great potential for applications in healthcare and diagnostics. However, the performance of these sensors in practical usage scenarios is often limited due to interference from the sample matrix. This work shows how the co-immobilization of glycol (PEG) diluents or ?back filling? of the DNA sensing layer can successfully address these problems. A novel SPR based melting assay is used for the analysis of a synthetic oligomer target as well as PCR amplified genomic DNA extracted from Legionella pneumophila. The benefits of sensing layer back filling on the assay performance are first demonstrated through melting analysis of the oligomer target and it is shown how back filling enables accurate discrimination of Legionella pneumophila serogroups directly from the PCR reaction product with complete suppression of sensor fouling.