Kinetically Controlled Site-Specific Self-assembly of Hairy Colloids.

The solvophobicity-driven directional self-assembly of polymer-coated gold nanorods is a well-established phenomenon. Yet, the kinetics of this process, the origin of site-selectivity in the self-assembly, and the interplay of (attractive) solvophobic brush interactions and (repulsive) electrostatic forces are not fully understood. Herein, we use a combination of time-resolved (vis/NIR) extinction spectroscopy and finite-difference time-domain (FDTD) simulations to determine conversion profiles for the assembly of gold nanorods with polystyrene shells of distinct thicknesses into their (tip-to-tip) self-assembled structures. In particular, we demonstrate that the assembly process is highly protracted compared with diffusion-controlled rates, and we find that the assembly rate varies for different thickness values of the polymer shell. Our findings were rationalized using coarse-grained molecular dynamics simulations, which also corroborated the tip-to-tip preference in the self-assembly process, albeit with a uniform polymer coating. Utilizing the knowledge of quantified conversion rates for distinct colloidal species, we designed coassembling systems with different brush thicknesses, featuring "narcissistic" self-sorting behavior. This provides new perspectives for high-level supracolloidal self-assembly.

Turning on hotspots: supracolloidal SERS probes made brilliant by an external activation mechanism.

We achieved external activation of local hot-spot sites in supracolloidal assembly structures. The concept was demonstrated by boosting surface-enhanced Raman scattering (SERS) efficiency by one order of magnitude through a heating-induced process. Our approach involves assembling gold nanoparticles with distinct dimensions, i.e. 16 and 80 nm, into well-defined planet-satellite-type arrangement structures using thermoresponsive (poly(N-isopropylacrylamide)) star polymer linkers. Insights into the assembly process were obtained by calculations within the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory framework. We observe one order of magnitude increase in SERS enhancement by a heating-induced volume-phase transition. This magnification aligns with simulations run using the finite-difference time-domain (FDTD) method. The implications of this adaptive supracolloidal concept are twofold: Firstly, our approach bypasses limitations of existing systems that are associated with the limited accessibility of electromagnetic hot-spot sites in strongly coupled, static assemblies of plasmonic nanoparticles, by providing the capability of dynamic hot-spot re-configuration. Second, these externally activated probes offer promising opportunities for the development of messenger materials and associated sensing strategies.

Super-Radiant SERS Enhancement by Plasmonic Particle Gratings.

Despite recent developments, surface-enhanced Raman spectroscopy (SERS) applications face challenges in achieving both high sensitivity and uniform Raman signals over a large area. Using the directional self-assembly of plasmonic nanoparticles in lattice structures, we show how one can increase the SERS signal 43-fold over randomly aligned gold nanoparticles without relying on the photoluminescence of Rhodamine 6G. For this study, we have chosen the lattice constant for an off-resonant case that matches the lattice resonance and super-radiant plasmon mode along the particle chain. Supported by electromagnetic simulations, we systematically analyze the radiative components of the plasmon modes by varying the particle size while keeping the lattice periodicity constant. We perform polarization-dependent SERS measurements and compare them with other standard SERS excitation wavelengths. Using the self-assembled plasmonic particle lattice, we have developed an effective SERS substrate that provides a significantly higher signal with 73% less surface coverage. This colloidal approach enables the cost-effective and scalable fabrication of highly sensitive, uniform, and polarization-dependent SERS substrates.

A Quasi-2D Polypyrrole Film with Band-Like Transport Behavior and High Charge-Carrier Mobility.

Quasi-2D (q2D) conjugated polymers (CPs) are polymers that consist of linear CP chains assembled through non-covalent interactions to form a layered structure. In this work, the synthesis of a novel crystalline q2D polypyrrole (q2DPPy) film at the air/H2 SO4 (95%) interface is reported. The unique interfacial environment facilitates chain extension, prevents disorder, and results in a crystalline, layered assembly of protonated quinoidal chains with a fully extended conformation in its crystalline domains. This unique structure features highly delocalized π-electron systems within the extended chains, which is responsible for the low effective mass and narrow electronic bandgap. Thus, the temperature-dependent charge-transport properties of q2DPPy are investigated using the van der Pauw (vdP) method and terahertz time-domain spectroscopy (THz-TDS). The vdP method reveals that the q2DPPy film exhibits a semiconducting behavior with a thermally activated hopping mechanism in long-range transport between the electrodes. Conversely, THz-TDS reveals a band-like transport, indicating intrinsic charge transport up to a record short-range high THz mobility of ≈107.1 cm2 V-1 s-1 .

The Rise of Structurally Anisotropic Plasmonic Janus Gold Nanostars.

Nanostructures intrinsically possessing two different structural or functional features, often called Janus nanoparticles, are emerging as a potential material for sensing, catalysis, and biomedical applications. Herein, we report the synthesis of plasmonic gold Janus nanostars (NSs) possessing a smooth concave pentagonal morphology with sharp tips and edges on one side and, contrastingly, a crumbled morphology on the other. The methodology reported herein for their synthesis - a single-step growth reaction - is different from any other Janus nanoparticle preparation involving either template-assisted growth or a masking technique. Interestingly, the coexistence of lower- and higher-index facets was found in these Janus NSs. The general paradigm for synthesizing gold Janus NSs was investigated by understanding the kinetic control mechanism with the combinatorial effect of all the reagents responsible for the structure. The optical properties of the Janus NSs were realized by corelating their extinction spectra with the simulated data. The size-dependent surface-enhanced Raman scattering (SERS) activity of these Janus NSs was studied with 1,4-BDT as the model analyte. Finite-difference time-domain simulations for differently sized particles revealed the distribution of electromagnetic hot-spots over the particles resulting in enhancement of the SERS signal in a size-dependent manner.

Block Copolymer-Templated Au@CdSe Core-Satellite Nanostructures with Solvent-Dependent Optical Properties.

In the present work, we report the fabrication and characterization of well-defined core-satellite nanostructures. These nanostructures comprise block copolymer (BCP) micelles, containing a single gold nanoparticle (AuNP) in the core and multiple photoluminescent cadmium selenide (CdSe) quantum dots (QDs) attached to the micelle's coronal chains. The asymmetric polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) BCP was employed to develop these core-satellite nanostructures in a series of P4VP-selective alcoholic solvents. The BCP micelles were first prepared in 1-propanol and subsequently mixed with AuNPs, followed by gradual addition of CdSe QDs. This method resulted in the development of spherical micelles that contained a PS/Au core and a P4VP/CdSe shell. These core-satellite nanostructures, developed in different alcoholic solvents, were further employed for the time-resolved photoluminescence analysis. It was found that solvent-selective swelling of the core-satellite nanostructures tunes the distance between the QDs and AuNPs and modulates their Förster resonance energy transfer (FRET) behavior. The average lifetime of the donor emission varied from 12.3 to 10.3 nanoseconds (ns) with the change in the P4VP-selective solvent within the core-satellite nanostructures. Furthermore, the distances between the donor and acceptor were also calculated using efficiency measurements and corresponding Förster distances. The resulting core-satellite nanostructures hold promising potential in various fields, such as photonics, optoelectronics, and sensors that utilize the FRET process.

Prevalence of HSPB6 gene variants in peripartum cardiomyopathy: Data from the German PPCM registry.

BACKGROUND: Heat shock protein family B (small) member 6 (HSPB6) mediates cardioprotective effects against stress-induced injury. In humans two gene variants of HSPB6 have been identified with a prevalence of 1% in patients with dilated cardiomyopathy (DCM). Peripartum cardiomyopathy (PPCM) is a potentially life-threatening heart disease of unknown etiology in previously healthy women of whom 16-20% of PPCM carry gene variants associated with cardiomyopathy. This study was designed to analyze the prevalence of pathogenic HSPB6 gene variants in PPCM. METHODS AND RESULTS: Whole-exome sequencing was performed in whole blood samples of PPCM patients (n = 65 PPCM patients from the German PPCM registry) and screened subsequently for HSPB6 gene variants. In this PPCM cohort one PPCM patient carries a HSPB6 gene variant of uncertain significance (VUS), which was not associated with changes in the amino acid sequence and no likely pathogenic or pathogenic variants were detected. CONCLUSION: HSPB6 gene variants did not occur more frequently in a cohort of PPCM patients from the German PPCM registry, compared to DCM patients. Genetic analyses in larger cohorts and in cohorts of different ethiologies of PPCM patients are needed to address the role of the genetic background in the pathogenesis of PPCM.

Mechanochemical Activation of Anthracene [4+4] Cycloadducts.

Controlled formation and breaking of weak chemical bonds is a versatile method for modifying the properties of materials. Anthracene [4+4] cycloadducts are a prime example that can be formed by light and opened by external forces. We address the theoretical description of mechanochemistry of these cycloadducts, where the standard constraint geometry simulates forces approach fails due to the lack of consideration of temperature. Explicit inclusion of external forces reveals the corresponding transition barriers that are clearly dominated by rupture of the [4+4] inter-anthracene bonds. Other bonds come into play at extremely large forces only, which cannot be expected to be reached under ambient conditions. The theoretical results are in line with the experimental rheology of [4+4]-linked anthracene polymers, which indicates reversible re-formation of [4+4] cycloaddition bonds with ultraviolet light after mechanochemical bond breaking due to applied shear stress.

Directional Amplified Photoluminescence through Large-Area Perovskite-Based Metasurfaces.

Perovskite nanocrystals are high-performance, solution-processed materials with a high photoluminescence quantum yield. Due to these exceptional properties, perovskites can serve as building blocks for metasurfaces and are of broad interest for photonic applications. Here, we use a simple grating configuration to direct and amplify the perovskite nanocrystals' original omnidirectional emission. Thus far, controlling these radiation properties was only possible over small areas and at a high expense, including the risks of material degradation. Using a soft lithographic printing process, we can now reliably structure perovskite nanocrystals from the organic solution into light-emitting metasurfaces with high contrast on a large area. We demonstrate the 13-fold amplified directional radiation with an angle-resolved Fourier spectroscopy, which is the highest observed amplification factor for the perovskite-based metasurfaces. Our self-assembly process allows for scalable fabrication of gratings with predefined periodicities and tunable optical properties. We further show the influence of solution concentration on structural geometry. By increasing the perovskite concentration 10-fold, we can produce waveguide structures with a grating coupler in one printing process. We analyze our approach with numerical modeling, considering the physiochemical properties to obtain the desired geometry. This strategy makes the tunable radiative properties of such perovskite-based metasurfaces usable for nonlinear light-emitting devices and directional light sources.

Clinical characteristics and long-term outcomes in patients with peripartum cardiomyopathy (PPCM) receiving left ventricular assist devices (LVAD).

BACKGROUND: Peripartum cardiomyopathy (PPCM) is a rare cause of heart failure (HF), presenting with left ventricular (LV) systolic dysfunction either at the end of pregnancy or in the months following delivery. In rare cases, PPCM leads to severe impairment of LV function, refractory cardiogenic shock or advanced HF. LV assist devices (LVAD) have been shown to be a feasible treatment option in advanced HF. However, little is known about long-term outcomes and prognosis of PPCM patients undergoing LVAD implantation. METHODS: A retrospective analysis of data from PPCM patients undergoing LVAD implantation in two tertiary centers with respect to long-term outcomes was performed. RESULTS: Twelve patients of median age 30 (18-39) years were included. Eight patients were experiencing cardiogenic shock (INTERMACS 1) at implantation. Seven patients were implanted within 1 month of their PPCM diagnosis. Median duration of LVAD support was 19 (2-92) months with median follow up of 67 (18-136) months (100% complete). In-hospital and 1-year mortality were 0% and 8.3%, respectively. Two patients died on LVAD support, four patients were successfully bridged to transplantation, two patients are still on LVAD, and four were successfully weaned due to sufficient LV recovery (one died after LV function deteriorated again). CONCLUSION: LVAD treatment of decompensated end-stage PPCM is feasible. Early LVAD provision led to hemodynamic stabilization in our cohort and facilitated safe LV recovery in one third of these young female patients.

[Peripartum Cardiomyopathy]. / Peripartale Kardiomyopathie.

Peripartum cardiomyopathy (PPCM) is a rare but potentially life-threatening heart disease, with onset in the last month of pregnancy or in the first months after delivery in previously heart-healthy women. PPCM patients typically present with heart failure due to left ventricular (LV) dysfunction with an LV ejection fraction (EF) < 45 %. In the last years clinical and experimental studies contributed to a better understanding of the pathophysiology and the clinical course of PPCM. In the context of oxidative stress, the nursing hormone prolactin is cleaved into a smaller antiangiogenic and proapoptotic 16k Da form, leading to myocardial dysfunction. In an animal model this can be prevented by treatment with the dopamine agonist bromocriptine, which suppresses prolactin release. This therapeutic approach was confirmed in several clinical studies. Therefore, the current guidelines recommend a treatment consisting of a heart failure treatment according to current guidelines in combination with the dopamine agonist bromocriptine. If the diagnosis is made early and the treatment is started immediately, the prognosis is good compared to other forms of cardiomyopathies, as LV function recovers in most cases.In the acute phase the severity of heart failure differs among PPCM patients. Some patients present with mild forms, whereas some PPCM patients display severely reduced LV function and cardiogenic shock. Especially the latter cases are still challenging, as treatment with ß1-adrenergic receptor agonists is associated with progression of heart failure and a worse cardiac outcome. Therefore, patients with cardiogenic shock complicating PPCM should be treated in centers experienced in mechanical circulatory support in combination with bromocriptine treatment.

Novel Therapeutic Strategies to Reduce Reperfusion Injury After Acute Myocardial Infarction.

For almost 30 years, urgent revascularization termed primary percutaneous coronary intervention has been a cornerstone of modern care for acute myocardial infarction (AMI). It lowers mortality and improved cardiovascular outcome compared to conservative therapy including thrombolysis. Reperfusion injury, which occurs after successful re-opening of the formerly occluded coronary artery, had been exploited as a potential therapeutic target. When revascularization became faster and primary percutaneous coronary intervention was successfully performed within 60-90 minutes of symptom onset, the interest in a potential additive effect of targeting reperfusion injury vanished. More recently, several meta-analyses indicated that limiting reperfusion injury prevents microvascular obstruction and reduces final infarct size, thereby lowering the probability of heart failure events and improving quality of life in AMI survivors. Here, we describe the current strategies to limit reperfusion injury and to improve post-AMI outcomes such as systemic or intracoronary hypothermia, left-ventricular unloading, intracoronary infusion of super-saturated oxygen, intermittent coronary sinus occlusion, and C-reactive protein apheresis.

Disentangling the Orientations of Spectrally Overlapping Transition Dipoles in Dense Dye Layers.

The transition dipole orientations of dye assemblies in heterostructures have a crucial impact on the efficiency of novel optoelectronic devices such as organic thin-film transistors and light-emitting diodes. These devices are frequently based on heterojunctions and tandem structures featuring multiple optical transitions. Precise knowledge of preferred orientations, spatial order, and spatial variations is highly relevant. We present a fast and universal large-area screening method to determine the transition dipole orientations in dye assemblies with diffraction-limited spatial resolution. Moreover, our hyperspectral imaging approach disentangles the orientations of different chromophores. As a demonstration, we apply our technique to dye monolayers with two optical transitions sandwiched between two ultrathin silicate nanosheets. A comprehensive model for dipole orientation distributions in monolayers reveals a long-range orientational order and a strong correlation between the two transitions.

Intracoronary Application of Super-Saturated Oxygen to Reduce Infarct Size Following Myocardial Infarction.

Optimal medical therapy for secondary prevention following acute myocardial infarction reduces non-fatal ischaemic events. Intensive antithrombotic or lipid-lowering approaches have failed to significantly lower mortality. In the past, reduction of infarct size in patients undergoing primary percutaneous revascularisation for acute myocardial infarction had been considered as a surrogate outcome marker. However, infarct size measured by magnetic resonance imaging or SPECT is strongly associated with all-cause mortality and hospitalization for heart failure within the first year after an acute myocardial infarction. Intracoronary administration of super-saturated oxygen (SSO2) immediately after revascularisation is an approach that can be used to reduce infarct size and, therefore, improve cardiovascular outcome in patients with acute myocardial infarction. In this article, we describe the modulation of pathophysiology by SSO2, review the existing trial data and present our first impressions with the technique in real clinical practice.

Complex Metal Nanostructures with Programmable Shapes from Simple DNA Building Blocks.

Advances in DNA nanotechnology allow the design and fabrication of highly complex DNA structures, uisng specific programmable interactions between smaller nucleic acid building blocks. To convey this concept to the fabrication of metallic nanoparticles, an assembly platform is developed based on a few basic DNA structures that can serve as molds. Programming specific interactions between these elements allows the assembly of mold superstructures with a range of different geometries. Subsequent seeded growth of gold within the mold cavities enables the synthesis of complex metal structures including tightly DNA-caged particles, rolling-pin- and dumbbell-shaped particles, as well as T-shaped and loop particles with high continuity. The method further supports the formation of higher-order assemblies of the obtained metal geometries. Based on electrical and optical characterizations, it is expected that the developed platform is a valuable tool for a self-assembly-based fabrication of nanoelectronic and nanooptic devices.

Mechano-tunable chiral metasurfaces via colloidal assembly.

Dynamic control of circular polarization in chiral metasurfaces is being used in many photonic applications. However, simple fabrication routes to create chiral materials with considerable and fully tunable chiroptical responses at visible and near-infrared wavelengths are scarce. Here, we describe a scalable bottom-up approach to construct cross-stacked nanoparticle chain arrays that have a circular dichroism of up to 11°. Due to their layered design, the strong superchiral fields of the inter-layer region are accessible to chiral analytes, resulting in a tenfold enhanced sensitivity in a chiral sensing proof-of-concept experiment. In situ restacking and local mechanical compression enables full control over the entire set of circular dichroism characteristics, namely sign, magnitude and spectral position. Strain-induced reconfiguration opens up an intriguing route towards actively controlled pixel arrays using local deformation, which fosters continuous polarization engineering and multi-channel detection.

Advanced Preconditioning: Impella 5.5 Support for Decompensated Heart Failure Before Left Ventricular Assist Device Surgery.

Left ventricular assist devices (LVAD) are increasingly used in patients with advanced heart failure, and available devices and surgical techniques have strongly evolved over time. Adequate recompensation of patients before surgery is important for optimal surgical outcomes. However, patients with terminal heart failure frequently suffer from cardiorenal syndrome, which complicates recompensation by medical means. Here, we report on the use of an Impella 5.5 microaxial pump for supporting a patient with severely decompensated heart failure before LVAD implantation, which resulted in hemodynamic stabilization and effective recompensation prior to surgery.

Casting of Gold Nanoparticles with High Aspect Ratios inside DNA Molds.

DNA nanostructures provide a powerful platform for the programmable assembly of nanomaterials. Here this approach is extended to synthesize rod-like gold nanoparticles in a full DNA controlled manner. The approach is based on DNA molds containing elongated cavities. Gold is deposited inside the molds using a seeded-growth procedure. By carefully exploring the growth parameters it is shown that gold nanostructures with aspect ratios of up to 7 can be grown from single seeds. The highly anisotropic growth is in this case controlled only by the rather soft and porous DNA walls. The optimized seeded growth procedure provides a robust and simple routine to achieve continuous gold nanostructures using DNA templating.

Assessment of major mental disorders in a German peripartum cardiomyopathy cohort.

AIMS: Peripartum cardiomyopathy (PPCM) is a heart disease affecting women during the last month of pregnancy or in the first months after delivery. The impact of the disease on mental health is largely unknown. METHODS AND RESULTS: Major mental disorders were assessed by a structured clinical interview in 40 patients with a confirmed PPCM diagnosis, and the data were compared with published prevalence in postpartum women. Circulating biomarkers associated with mental health, such as kynurenine, serotonin, and microRNA (miR)-30e, were evaluated in PPCM and compared with matched healthy pregnancy-matched postpartum controls (PP-Ctrl). Major mental disorders were diagnosed in 65% (26/40) of the PPCM cohort. The prevalence for major depressive disorders was 4-fold, for post-traumatic stress disorder 14-fold, and for panic disorder 6-fold higher in PPCM patients compared with postpartum women without a PPCM diagnosis. Compared with PP-Ctrl, PPCM patients displayed elevated levels of serum kynurenine (P < 0.01), reduced levels of serum serotonin (P < 0.05), and elevated levels of plasma miR-30e (P < 0.05). CONCLUSIONS: The majority of PPCM patients in the present cohort displayed mental disorders with a higher prevalence of major depressive disorders, post-traumatic stress disorder (PTBS), and panic disorder, compared with postpartum women without a PPCM diagnosis. This higher prevalence was associated with an impaired tryptophan metabolism and elevated levels of the depression-associated miR-30e, suggesting a potential predisposition for mental disorders at the time of PPCM diagnosis. Consequently, physicians should be aware of the increased risk for mental disorders in PPCM patients, and psychiatric assessment should be included in the diagnosis and management of PPCM patients.

Outcome in German and South African peripartum cardiomyopathy cohorts associates with medical therapy and fibrosis markers.

AIMS: This study aims to compare the clinical course of peripartum cardiomyopathy (PPCM) cohorts from Germany (G-PPCM) and South Africa (SA-PPCM) with fibrosis-related markers to get insights into novel pathomechanisms of PPCM. METHODS AND RESULTS: G-PPCM (n = 79) and SA-PPCM (n = 72) patients and healthy pregnancy-matched women from Germany (n = 56) and South Africa (n = 40) were enrolled. Circulating levels of procollagen type-I (PINP) and type-III (PIIINP) N-terminal propeptides, soluble ST2, galectin-3, and full-length and cleaved osteopontin (OPN) were measured at diagnosis (baseline) and 6 months of follow-up. Both cohorts received standard heart failure therapy while anticoagulation therapy was applied in 100% of G-PPCM but only in 7% of SA-PPCM patients. In G-PPCM patients, baseline left ventricular ejection fraction (LVEF) was lower, and outcome was better (baseline LVEF, 24 ± 8%, full recovery: 52%, mortality: 0%) compared with SA-PPCM patients (baseline LVEF: 30 ± 9%, full recovery: 32%, mortality: 11%; P < 0.05). At baseline, PINP/PIIINP ratio was lower in SA-PPCM and higher in G-PPCM compared with respective controls, whereas total OPN was elevated in both collectives. Cleaved OPN, which increases PIIINP levels, is generated by thrombin and was reduced in patients receiving anticoagulation therapy. High baseline galectin-3, soluble ST2, and OPN levels were associated with poor outcome in all PPCM patients. CONCLUSIONS: SA-PPCM patients displayed a more profibrotic biomarker profile, which was associated with a less favourable outcome despite better cardiac function at baseline, compared with G-PPCM patients. Use of bromocriptine and anticoagulation therapy in G-PPCM may counteract fibrosis and may in part be responsible for their better outcome.