Jan Becker

Synthesis of Rod-Shaped Gold Nanorattles with Improved Plasmon Sensitivity and Catalytic Activity

We prepared rod-shaped gold nanorattles solid gold nanorods surrounded by a thin gold shell using a galvanic replacement process starting with silver-coated gold nanorods. These structures are very promising candidates for catalytic applications and optimized plasmon sensors. They combine the advantages of rods (low plasmon resonance frequency, large polarizability, small damping) with the high surface area of hollow structures. The plasmon sensitivity to changes in the dielectric environment is up to 50% higher for gold nanorattles compared to gold nanorods with the same resonance frequency and 6x higher than for plasmons in spherical gold nanoparticles. The catalytic activity measured for the reduction of p-nitrophenol is 4x larger than for bare gold nanorods.

Nanoassembled Plasmonic-Photonic Hybrid Cavity for Tailored Light-Matter Coupling

We propose and demonstrate a hybrid cavity system in which metal nanoparticles are evanescently coupled to a dielectric photonic crystal cavity using a nanoassembly method. While the metal constituents lead to strongly localized fields, optical feedback is provided by the surrounding photonic crystal structure. The combined effect of plasmonic field enhancement and high quality factor (Q approximately 900) opens new routes for the control of light-matter interaction at the nanoscale.

Au@MnO Nanoflowers: Hybrid Nanocomposites for Selective Dual Functionalization and Imaging

Recently, the development of hybrid nanostructures consisting of various materials has attracted considerable interest. The assembly of different nanomaterials with specific optical, magnetic, or electronic properties to multicomponent composites can change and even enhance the properties of the individual constituents. Specifically tuning the structure and interface interactions within the nanocomposites has resulted in novel platforms of materials that may lead the way to various future technologies, such as synchronous biolabeling, protein separation and detection, heterogeneous catalysis, and multimodal imaging in biomedicine. Of the various kinds of nanomaterials, gold nanorods show an unusually high polarizability at optical frequencies arising from the excitation of localized surface-plasmon resonances (LSPRs). Furthermore, gold nanorods have promising therapeutic properties as hyperthermal agents because the local temperature around the gold nanorods can be increased by laser illumination through the tunable surface plasmon bands in the near infrared (NIR) region. Using NIR radiation for hyperthermal therapy is beneficial because of the low absorption and low scattering by blood and tissue in this spectral range. Magnetic nanoparticles constitute another major class of nanomaterials that have attracted much research effort over the past decades. In particular, exchange-coupled magnetic nanocomposites, such as antiferromagnetic/ferromagnetic core–shell nanoparticles, such as MnO/Mn3O4, have magnetic properties that are quite different from those of the individual components. Concerning biomedical applications, superparamagnetic nanoparticles are attractive as contrast agents for magnetic resonance imaging (MRI). The majority of nanoparticles that have been investigated in this field comprise iron oxides (Fe3O4, g-Fe2O3), which are known to shorten the transverse (or spin–spin) relaxation time T2. [11] Recently, manganese oxide nanoparticles (MnO NPs) have been shown to be interesting candidates as contrast agents for shortening of the longitudinal (or spin-lattice) relaxation time T1. [12] Consequently, a nanoparticulate system containing both an optically active plasmonic gold unit and a magnetically active MnO component would be advantageous for simultaneous optical and MRI detection. Although considerable research efforts have been put into the chemical design of suitable surface ligands, one of the major obstacles for biocompatible applications remains the lack of surface addressability. Therefore, a nanocomposite made up of individually addressable Au and MnO domains offers two functional surfaces for the attachment of different kinds of molecules, thus increasing both diagnostic and therapeutic potential. Furthermore, the size of either of the two components can be varied to optimize the magnetic and optical properties. Herein we present the successful synthesis of Au@MnO nanocomposites consisting of both paramagnetic MnO NPs and Au crystallites followed by separate surface functionalization of both domains with fluorescent ligands. Scheme 1 depicts a functionalized Au@MnO nanoflower with selective attachment of catechol anchors to the metal oxide petals and thiol anchors to the gold core. The nanoflowers were synthesized by decomposition of manganese acetylacetonate [Mn(acac)2] in diphenyl ether in the presence of preformed Au NPs (“seeds”), with oleic acid and oleylamine as surfactants, following a similar procedure for the preparation of Au@Fe3O4 heteroparticles by Sun et al. [15] The [*] T. D. Schladt, Dr. M. I. Shukoor, K. Schneider, Dr. M. N. Tahir, O. K hler, Prof. Dr. W. Tremel Institut f r Anorganische Chemie und Analytische Chemie Johannes-Gutenberg-Universit t Duesbergweg 10–14, 55099 Mainz (Germany) Fax: (+49)6131-39-25605 E-mail: tremel@uni-mainz.de

Highly sensitive plasmonic silver nanorods.

We compare the single-particle plasmonic sensitivity of silver and gold nanorods with similar resonance wavelengths by monitoring the plasmon resonance shift upon changing the environment from water to 12.5% sucrose solution. We find that silver nanoparticles have 1.2 to 2 times higher sensitivity than gold, in good agreement with simulations based on the boundary-elements-method (BEM). To exclude the effect of particle volume on sensitivity, we test gold rods with increasing particle width at a given resonance wavelength. Using the Drude-model of optical properties of metals together with the quasi-static approximation (QSA) for localized surface plasmons, we show that the dominant contribution to higher sensitivity of silver is the lower background polarizability of the d-band electrons and provide a simple formula for the sensitivity. We improve the reversibility of the silver nanorod sensors upon repeated cycles of environmental changes by blocking the high energy parts of the illumination light.

Protein-Membrane Interaction Probed by Single Plasmonic Nanoparticles

We present a nanosized and addressable sensor platform based on membrane coated plasmonic particles and show unequivocally the covering with lipid bilayers as well as the subsequent detection of streptavidin binding to biotinylated lipids. The binding is detected on membrane covered gold nanorods by monitoring the spectral shift by fast single particle spectroscopy (fastSPS) on many particles in parallel. Our approach allows for local analysis of protein interaction with biological membranes as a function of the lateral composition of phase separated membranes.

Mapping the polarization pattern of plasmon modes reveals nanoparticle symmetry.

We study the wavelength and polarization dependent plasmon resonances of single silver and gold nanorods, triangles, cubes, and dimers with a novel single particle spectroscopy method (RotPOL). In RotPOL, a rotating wedge-shaped polarizer encodes the full polarization information of each particle within one image. This reveals the symmetry of the particles and their plasmon modes, allows analyzing inhomogeneous samples and the monitoring of particle shape changes during growth in situ.

Online Self-Help as an Add-On to Inpatient Psychotherapy: Efficacy of a New Blended Treatment Approach

Background: Depression is one of the most frequent and costly mental disorders. While there is increasing evidence for the efficacy of online self-help to improve depression or prevent relapse, there is little evidence in blended care settings, especially combined with inpatient face-to-face psychotherapy. Therefore, we evaluated whether an evidence-based online self-help program improves the efficacy of inpatient psychotherapy. Methods: A total of 229 depressed patients were randomly allocated either to an online self-help program (intervention group [IG]; Deprexis) or an active control group (CG; weekly online information on depression) in addition to inpatient psychodynamic psychotherapy. Both groups had access to their respective experimental intervention for 12 weeks, regardless of inpatient treatment duration. Reduction of depressive symptoms, as measured with the Beck Depression Inventory-II, was the primary outcome at the end of the intervention (T2). Results: Depressive symptoms were statistically significantly lower in the IG compared to the active CG at T2 with a moderate between-group effect size of d = 0.44. The same applied to anxiety (d = 0.33), quality of life (d = 0.34), and self-esteem (d = 0.38) at discharge from inpatient treatment (T1). No statistically significant differences were found regarding dysfunctional attitudes (d = 0.14) and work ability (d = 0.08) at T1. Conclusions: This is the first evidence for blended treatment combining online self-help with inpatient psychotherapy. The study opens new and promising avenues for increasing the efficacy of inpatient psychotherapy. Future studies should determine how integration of online self-help into the therapeutic process can be developed further.

Evaluation of a video-based Internet intervention as preparation for inpatient psychosomatic rehabilitation: study protocol for a randomized controlled trial

BackgroundPatients’ treatment expectations are a key factor in psychotherapy. Several studies have linked higher expectations to better treatment success. Therefore, we want to evaluate the impact of a targeted video-based intervention on patients’ expectations and the treatment success of inpatient rehabilitation.Methods/designAll patients who will be referred to inpatient psychosomatic rehabilitation in three clinics will receive a study flyer with information about how to log in to the study platform together with the usual clinic information leaflet. Patients will receive the study information and informed consent upon login and will be randomized into the intervention or the control group. The intervention group (n = 394) will get access to our virtual online clinic, containing several videos about inpatient rehabilitation, until their admission to inpatient rehabilitation. The control group (n = 394) will receive no special treatment preparation. Questionnaires will be given at study inclusion (T0), two weeks before admission to (T1), and at the end of (T2) inpatient rehabilitation. The primary outcome is the outcome expectancy measured with the Credibility Expectancy Questionnaire at T1. Secondary outcomes include treatment motivation, mental health, work ability, depression, anxiety, and satisfaction with and usage of the Internet platform.DiscussionWe expect the intervention group to benefit from the additional preparation concerning their outcome expectancy. If successful, this approach could be used in the future to enhance the efficacy of inpatient rehabilitation.Trial registrationClinicalTrials.gov: NCT02532881. Registered on 25 August 2015.

Evaluation of a transdiagnostic psychodynamic online intervention to support return to work: A randomized controlled trial

Objectives Given their flexibility, online interventions may be useful as an outpatient treatment option to support vocational reintegration after inpatient rehabilitation. To that purpose we devised a transdiagnostic psychodynamic online intervention to facilitate return to work, focusing on interpersonal conflicts at the workplace often responsible for work-related stress. Research design and methods In a randomized controlled trial, we included employed patients from cardiologic, psychosomatic and orthopedic rehabilitation with work-related stress or need for support at intake to inpatient rehabilitation after they had given written consent to take part in the study. Following discharge, maladaptive interpersonal interactions at the workplace were identified via weekly blogs and processed by written therapeutic comments over 12 weeks in the intervention group (IG). The control group (CG) received an augmented treatment as usual condition. The main outcome, subjective prognosis of gainful employment (SPE), and secondary outcomes (psychological complaints) were assessed by means of online questionnaires before, at the end of aftercare (3 months) and at follow-up (12 months). We used ITT analyses controlling for baseline scores and medical group. Results N = 319 patients were enrolled into IG and N = 345 into CG. 77% of the IG logged in to the webpage (CG 74%) and 65% of the IG wrote blogs. Compared to the CG, the IG reported a significantly more positive SPE at follow-up. Measures of depression, anxiety and psychosocial stressors decreased from baseline to follow-up, whereas the corresponding scores increased in the CG. Correspondingly, somatization and psychological quality of life improved in the IG. Conclusions Psychodynamic online aftercare was effective to enhance subjective prognosis of future employment and improved psychological complaints across a variety of chronic physical and psychological conditions, albeit with small effect sizes.

Transdiagnostic, Psychodynamic Web-Based Self-Help Intervention Following Inpatient Psychotherapy : Results of a Feasibility Study and Randomized Controlled Trial.

Background Mental disorders have become a major health issue, and a substantial number of afflicted individuals do not get appropriate treatment. Web-based interventions are promising supplementary tools for improving health care for patients with mental disorders, as they can be delivered at low costs and used independently of time and location. Although psychodynamic treatments are used frequently in the face-to-face setting, there has been a paucity of studies on psychodynamic Web-based self-help interventions. Objective The objective of this study was to determine the feasibility and preliminary efficacy of a transdiagnostic affect-focused psychodynamic Web-based self-help intervention designed to increase emotional competence of patients with mental disorders. Methods A total of 82 psychotherapy inpatients with mixed diagnoses were randomized into two groups. Following discharge, the intervention group (IG) got access to a guided version of the intervention for 10 weeks. After a waiting period of 10 weeks, the wait-list control group (WLCG) got access to an unguided version of the intervention. We reported the assessments at the beginning (T0) and at the end of the intervention, resp. the waiting period (T1). The primary outcome was satisfaction with the treatment at T1. Secondary outcome measures included emotional competence, depression, anxiety, and quality of life. Statistical analyses were performed with descriptive statistics (primary outcome) and analysis of covariance; a repeated measurement analysis of variance was used for the secondary outcomes. Effect sizes were calculated using Cohen d and data were analyzed as per protocol, as well as intention-to-treat (ITT). Results Patients were chronically ill, diagnosed with multiple diagnoses, most frequently with depression (84%, 58/69), anxiety (68%, 47/69), personality disorder (38%, 26/69), and depersonalization-derealization disorder (22%, 15/69). A majority of the patients (86%, 36/42) logged into the program, of which 86% (31/36) completed the first unit. Satisfaction with the units mastered was rated as good (52%, 16/31) and very good (26%, 9/31). However, there was a steady decline of participation over the course of the program; only 36% of the participants (13/36) participated throughout the trial completing at least 50% of the sessions. According to the ITT analysis, participants improved statistically significantly and with moderate effect sizes (Cohen d) compared with the WLCG regarding depression (d=0.60), quality of life (d=0.53), and emotional competence (d=0.49). Effects were considerably stronger for the completers with respect to depression (d=1.33), quality of life (d=0.83), emotional competence (d=0.68), and general anxiety (d=0.62). Conclusions Although overall program satisfaction and benefit of the program were favorable with respect to the indicators of emotional disorders, the rate of completion was low. Our findings point to the need to target the intervention more specifically to the needs and capabilities of participants and to the context of the intervention. Trial Registration Clinicaltrials.gov NCT02671929; https://clinicaltrials.gov/ct2/show/NCT02671929 (Archived by WebCite at http://www.webcitation.org/6ntWg1yWb)