Lignin Upconversion by Functionalization and Network Formation

Lignin, a complex and abundant biopolymer derived from plant cell walls, has emerged as a promising feedstock for sustainable material development. Due to the high abundance of phenylpropanoid units, aromatic rings, and hydroxyl groups, lignin is an ideal candidate for being explored in various material applications. Therefore, the demand on lignin valorization for development of value-added products is significantly increasing. This mini-review provides an overview of lignin upconversion, focusing on its functionalization through chemical and enzymatic routes, and its application in lignin-based polymer resins, hydrogels, and nanomaterials. The functionalization of lignin molecules with various chemical groups offers tailored properties and increased compatibility with other materials, expanding its potential applications. Additionally, the formation of lignin-based networks, either through cross-linking or blending with polymers, generates novel materials with improved mechanical, thermal, and barrier properties. However, challenges remain in optimizing functionalization techniques, preserving the innate complexity of lignin, and achieving scalability for industrial implementation. As lignin's potential continues to be unlocked, it is poised to contribute significantly to the shift towards more eco-friendly and resource-efficient industries.

Fabrication of Patchy Silica Microspheres with Tailor-Made Patch Functionality using Photo-Iniferter Reversible-Addition-Fragmentation Chain-Transfer (PI-RAFT) Polymerization

Their inherent directional information renders patchy particles interesting building blocks for advanced applications in materials science. In this study, a feasible method to fabricate patchy silicon dioxide microspheres is demonstrated, which they are able to equip with tailor-made polymeric materials as patches. Their fabrication method relies on a solid-state supported microcontact printing (µCP) routine optimized for the transfer of functional groups to capillary-active substrates, which is used to introduce amino functionalities as patches to a monolayer of particles. Acting as anchor groups for polymerization, photo-iniferter reversible addition-fragmentation chain-transfer (RAFT) is used to graft polymer from the patch areas. Accordingly, particles with poly(N-acryloyl morpholine), poly(N-isopropyl acrylamide), and poly(n-butyl acrylate) are prepared as representative acrylic acid-derived functional patch materials. To facilitate their handling in water, a passivation strategy of the particles for aqueous systems is introduced. The protocol introduced here, therefore, promises a vast degree of freedom in engineering the surface properties of highly functional patchy particles. This feature is unmatched by other techniques to fabricate anisotropic colloids. The method, thus, can be considered a platform technology, culminating in the fabrication of particles that possess locally precisely formed patches on particles at a low µm scale with a high material functionality.

Versatile Microfluidics Separation of Colloids by Combining External Flow with Light-Induced Chemical Activity

Separation of particles by size, morphology, or material identity is of paramount importance in fields such as filtration or bioanalytics. Up to now separation of particles distinguished solely by surface properties or bulk/surface morphology remains a very challenging process. Here a combination of pressure-driven microfluidic flow and local self-phoresis/osmosis are proposed via the light-induced chemical activity of a photoactive azobenzene-surfactant solution. This process induces a vertical displacement of the sedimented particles, which depends on their size and surface properties . Consequently, different colloidal components experience different regions of the ambient microfluidic shear flow. Accordingly, a simple, versatile method for the separation of such can be achieved by elution times in a sense of particle chromatography. The concepts are illustrated via experimental studies, complemented by theoretical analysis, which include the separation of bulk-porous from bulk-compact colloidal particles and the separation of particles distinguished solely by slight differences in their surface physico-chemical properties.

Proton Therapy for 166 Patients with Iris Melanoma: Side Effects and Oncologic Outcomes

OBJECTIVE

To investigate the oncologic and functional outcomes of a large cohort of patients with a favorable stage of circumscribed and diffuse iris melanoma who underwent primary proton treatment and the risk factors related to initial tumor characteristics and the treatment field architecture.

DESIGN

Retrospective, single-center, case study.

PARTICIPANTS

We reviewed 225 patients with iris melanoma who were consecutively treated with proton beam therapy at our institution between 1998 and 2020.

METHODS

We performed Kaplan-Meier time-to-event analyses and multivariate Cox proportional hazard analyses to identify the impacts of tumor characteristics and target volumes on oncologic and functional outcomes.

MAIN OUTCOME MEASURES

We measured local tumor control, eye preservation rates, metastasis-free survival, cataract and glaucoma-directed surgery, intraocular pressure, and changes in visual acuity.

RESULTS

Of the 192 patients with tumors confined to the iris (T1a-c) who underwent proton therapy as primary treatment, a total of 166 patients (mean age, 58.4 years; 88 women) with a minimum follow-up of 6 months were included. Multifocal or diffuse tumor spread was present in 77 (46.4%) patients. The median follow-up time was 54.0 (interquartile range, 27.4-91.8 months) months. Local recurrence occurred in 2 patients (1.2%) with circumscribed iris melanoma. Enucleation was a rare event (n = 5, 3%) and no patient developed metastatic disease. A large-treatment field (full aperture, involving > 10 clock hours) was identified as a risk factor for the development of secondary glaucoma (hazard ratio [HR], 6.3; P < 0.001) and subsequent surgical interventions (HR, 10.85; P < 0.001). The large-treatment field group showed a significant decline in visual acuity (logarithm of the minimum angle of resolution > 0.3; log-rank P < 0.0001), which was associated with secondary glaucoma (HR, 3.40; P = 0.002).

CONCLUSIONS

Proton therapy provides an effective, noninvasive treatment option for patients with a favorable stage of iris melanoma. Irradiation of the anterior segment for up to 10 clock hours is associated with a low risk of the development of secondary glaucoma and vision loss.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found after the references.

15 Years of Success and Still Improving: Polymers

In 2009, the inaugural issue of Polymers was released [...].

Treatment of neovascular age-related macular degeneration: insights into drug-switch real-world from the Berlin Macular Registry

PURPOSE

Bevacizumab, ranibizumab, and aflibercept are commonly used to treat neovascular age-related macular degeneration (nAMD). The results of various interventional, mostly randomized head-to-head studies, indicate statistical non-inferiority of these three drugs. The results of these studies are often interpreted as the three drugs being freely interchangeable, resulting in some health systems to pressure ophthalmologists to preferentially use the less expensive bevacizumab. This study analyzes switching from aflibercept or ranibizumab to bevacizumab and back under real-world conditions in order to investigate the assumption of interchangeability of the drugs.

METHODS

Treatment data of IVT patients with diagnosed nAMD were extracted from the clinical Berlin Macular Registry database. Patients who underwent a drug switch from aflibercept or ranibizumab to bevacizumab were subject of this study. Statistical comparisons were pre-planned for best corrected visual acuity, central retinal thickness, macular volume, and length of injection interval. Additional endpoints were analyzed descriptively.

RESULTS

Mean visual acuity decreased from 0.57 ± 0.05 under aflibercept/ranibizumab to 0.68 ± 0.06 logMAR after the switch (P = 0.001; N = 63). CRT increased from 308 ± 11 µm to 336 ± 16 µm (P = 0.011; N = 63). About half of the subjects were switched back: visual acuity increased from 0.69 ± 0.08 logMAR to 0.58 ± 0.09 logMAR (N = 26). CRT decreased from 396 ± 28 to 337 ± 20 µm (N = 28).

CONCLUSION

The data provides real-world evidence that there is loss of visual acuity and an increase in retinal edema after switching to bevacizumab. Thus, the assumption of free interchangeability cannot be confirmed in this cohort.

Impact of Adjuvant Ocular Interventions on the Quality of Life of Patients with Uveal Melanoma after Proton Beam Therapy

INTRODUCTION

Proton beam therapy is an established primary treatment for patients with nonmetastasized uveal melanoma. Adjuvant local interventions, like intravitreal injections or surgery, were shown to improve long-term eye preservation; however, their impact on the patient's quality of life (QOL) remains unknown.

METHODS

In a post-radiotherapeutic follow-up, we prospectively collected data on QOL, visual acuity, and interventional adjuvant procedures. QOL was measured with QOL-C30 questionnaire and quality of life questionnaire OPT30 at baseline, and at 3 and 12 months after proton therapy. Patients were grouped by the type of adjuvant treatment. The impact on QOL was analyzed by comparing changes in the mean score values and visual acuity for different interventional subgroups, with generalized linear mixed models and Wilcoxon signed-rank tests.

RESULTS

We received 108 (100%) and 95 (88.0%) questionnaires at 3 and 12 months post-therapy, respectively. Adjuvant interventions included observation (n = 61, 56.5%), intravitreal injections (n = 17, 15.7%), and an intraocular surgical procedure (n = 30, 27.8%). In the latter group, several QOL items significantly declined after the 3-month adjuvant interval, but they partially recovered at the 12-month follow-up. In all adjuvant-intervention groups, global QOL scores returned to baseline levels at 12 months.

CONCLUSION

Posttreatment adjuvant interventions had no long-lasting effects on QOL in patients with uveal melanoma.

A Dual pH‐ and Light‐Responsive Spiropyran‐Based Surfactant: Investigations on Its Switching Behavior and Remote Control over Emulsion Stability

A cationic surfactant containing a spiropyran unit is prepared exhibiting a dual‐responsive adjustability of its surface‐active characteristics. The switching mechanism of the system relies on the reversible conversion of the non‐ionic spiropyran (SP) to a zwitterionic merocyanine (MC) and can be controlled by adjusting the pH value and via light, resulting in a pH‐dependent photoactivity: While the compound possesses a pronounced difference in surface activity between both forms under acidic conditions, this behavior is suppressed at a neutral pH level. The underlying switching processes are investigated in detail, and a thermodynamic explanation based on a combination of theoretical and experimental results is provided. This complex stimuli‐responsive behavior enables remote‐control of colloidal systems. To demonstrate its applicability, the surfactant is utilized for the pH‐dependent manipulation of oil‐in‐water emulsions.

Synthesis of nanostructured protein-mineral-microcapsules by sonication

We propose a simple and eco-friendly method for the formation of composite protein-mineral-microcapsules induced by ultrasound treatment. Protein- and nanoparticle-stabilized oil-in-water (O/W) emulsions loaded with different oils are prepared using high-intensity ultrasound. The formation of thin composite mineral proteinaceous shells is realized with various types of nanoparticles, which are pre-modified with Bovine Serum Albumin (BSA) and subsequently characterized by EDX, TGA, zeta potential measurements and Raman spectroscopy. Cryo-SEM and EDX mapping visualizations show the homogeneous distribution of the densely packed nanoparticles in the capsule shell. In contrast to the results reported in our previous paper,¹ the shell of those nanostructured composite microcapsules is not cross-linked by the intermolecular disulfide bonds between BSA molecules. Instead, a Pickering-Emulsion formation takes place because of the amphiphilicity-driven spontaneous attachment of the BSA-modified nanoparticles at the oil/water interface. Using colloidal particles for the formation of the shell of the microcapsules, in our case silica, hydroxyapatite and calcium carbonate nanoparticles, is promising for the creation of new functional materials. The nanoparticulate building blocks of the composite shell with different chemical, physical or morphological properties can contribute to additional, sometimes even multiple, features of the resulting capsules. Microcapsules with shells of densely packed nanoparticles could find interesting applications in pharmaceutical science, cosmetics or in food technology.

Nanodeformations of microcapsules: comparing the effects of cross-linking and nanoparticles

The mechanical properties of proteinaceous and composite microcapsules loaded with oil were measured by SFM and evaluated using the Reissner model. Comparison of the obtained results reveals significantly higher Young’s moduli of protein capsules due to intermolecular crosslinking. In contrast, conformational restrictions in composite microcapsules inhibit protein crosslinking leading to the reduction of their elasticity.

SFM results for protein and composite microcapsules are evaluated by the Reissner model. Protein capsules show higher Young’s moduli due to crosslinking, which is absent in composite capsules because of restrictions in the protein conformations.

Protein Nanopore Membranes Prepared by a Simple Langmuir-Schaefer Approach

Filtration through membranes with nanopores is typically associated with high transmembrane pressures and high energy consumption. This problem can be addressed by reducing the respective membrane thickness. Here, a simple procedure is described to prepare ultrathin membranes based on protein nanopores, which exhibit excellent water permeance, two orders of magnitude superior to comparable, industrially applied membranes. Furthermore, incorporation of either closed or open protein nanopores allows tailoring the membrane's ion permeability. To form such membranes, the transmembrane protein ferric hydroxamate uptake protein component A (FhuA) or its open-pore variant are assembled at the air-water interface of a Langmuir trough, compressed to a dense film, crosslinked by glutaraldehyde, and transferred to various support materials. This approach allows to prepare monolayer or multilayer membranes with a very high density of protein nanopores. Freestanding membranes covering holes up to 5 μm in diameter are visualized by atomic force microscopy (AFM), helium ion microscopy, and transmission electron microscopy. AFM PeakForce quantitative nanomechanical property mapping (PeakForce QNM)  demonstrates remarkable mechanical stability and elastic properties of freestanding monolayer membranes with a thickness of only 5 nm. The new protein membrane can pave the way to energy-efficient nanofiltration.

Solid-Phase Microcontact Printing for Precise Patterning of Rough Surfaces: Using Polymer-Tethered Elastomeric Stamps for the Transfer of Reactive Silanes

We present a microcontact printing (μCP) routine suitable to introduce defined (sub-) microscale patterns on surface substrates exhibiting a high capillary activity and receptive to a silane-based chemistry. This is achieved by transferring functional trivalent alkoxysilanes, such as (3-aminopropyl)-triethoxysilane (APTES) as a low-molecular weight ink via reversible covalent attachment to polymer brushes grafted from elastomeric polydimethylsiloxane (PDMS) stamps. The brushes consist of poly{N-[tris(hydroxymethyl)-methyl]acrylamide} (PTrisAAm) synthesized by reversible addition-fragmentation chain-transfer (RAFT)-polymerization and used for immobilization of the alkoxysilane-based ink by substituting the alkoxy moieties with polymer-bound hydroxyl groups. Upon physical contact of the silane-carrying polymers with surfaces, the conjugated silane transfers to the substrate, thus completely suppressing ink-flow and, in turn, maximizing printing accuracy even for otherwise not addressable substrate topographies. We provide a concisely conducted investigation on polymer brush formation using atomic force microscopy (AFM) and ellipsometry as well as ink immobilization utilizing two-dimensional proton nuclear Overhauser enhancement spectroscopy (¹H-¹H-NOESY-NMR). We analyze the μCP process by printing onto Si-wafers and show how even distinctively rough surfaces can be addressed, which otherwise represent particularly challenging substrates.

Construction of Highly Ordered Glyco-Inside Nano-Assemblies through RAFT Dispersion Polymerization of Galactose-Decorated Monomer

Glyco-assemblies derived from amphiphilic sugar-decorated block copolymers (ASBCs) have emerged prominently due to their wide application, for example, in biomedicine and as drug carriers. However, to efficiently construct these glyco-assemblies is still a challenge. Herein, we report an efficient technology for the synthesis of glyco-inside nano-assemblies by utilizing RAFT polymerization of a galactose-decorated methacrylate for polymerization-induced self-assembly (PISA). Using this approach, a series of highly ordered glyco-inside nano-assemblies containing intermediate morphologies were fabricated by adjusting the length of the hydrophobic glycoblock and the polymerization solids content. A specific morphology of complex vesicles was captured during the PISA process and the formation mechanism is explained by the morphology of its precursor and intermediate. Thus, this method establishes a powerful route to fabricate glyco-assemblies with tunable morphologies and variable sizes, which is significant to enable the large-scale fabrication and wide application of glyco-assemblies.

Primary Vitreoretinal Lymphoma Therapy Monitoring: Significant Vitreous Haze Reduction After Intravitreal Rituximab

BACKGROUND/AIMS

Intravitreal rituximab is an off-label treatment option for primary vitreoretinal lymphoma (PVRL). The objective of this study was to monitor the therapeutic response and safety profile of intravitreal rituximab in a cohort of PVRL patients.

METHODS

In this retrospective, uncontrolled, open label, multicentre study, 20 eyes from 15 consecutive patients diagnosed with PRVL received at least one intravitreal injection of 1mg in 0.1ml rituximab. Biodata of the PVRL patients was recorded as well as visual acuity and vitreous haze score immediately before rituximab intravitreal injection and at follow-up examinations. Intravitreal rituximab safety data was also recorded. Additional rituximab injections were made during control visits on a pro re nata (PRN) regime using increased vitreous haze to indicate recurrence.

RESULTS

There was significant vitreous haze reduction (p=0.0002) followed by significant improvement of visual acuity (mean best visual acuity before therapy 0.57 logMAR, after therapy 0.20 logMAR (p=0.0228) during the follow-up time up to 4 years. Only mild ocular side effects were reported. Median follow-up time was 565 days (range, 7-1253 days).

CONCLUSION

Intravitreal rituximab therapy shows promising PVRL regression without any severe side effects. Although our clinical data support rituximab as intravitreal therapy in PVRL disease, further study is warranted.

About the mechanism of ultrasonically induced protein capsule formation

In this paper, we propose a consistent mechanism of protein microcapsule formation upon ultrasound treatment. Aqueous suspensions of bovine serum albumin (BSA) microcapsules filled with toluene are prepared by use of high-intensity ultrasound following a reported method. Stabilization of the oil-in-water emulsion by the adsorption of the protein molecules at the interface of the emulsion droplets is accompanied by the creation of the cross-linked capsule shell due to formation of intermolecular disulfide bonds caused by highly reactive species like superoxide radicals generated sonochemically. The evidence for this mechanism, which until now remained elusive and was not proven properly, is presented based on experimental data from SDS-PAGE, Raman spectroscopy and dynamic light scattering.

A consistent mechanism of protein microcapsule formation upon ultrasound treatment is proposed. The evidence for this mechanism is based on experimental data from SDS-PAGE, Raman spectroscopy and dynamic light scattering.

Self-Assembly Behavior of Oppositely Charged Inverse Bipatchy Microcolloids

A directed attractive interaction between predefined "patchy" sites on the surfaces of anisotropic microcolloids can provide them with the ability to self-assemble in a controlled manner to build target structures of increased complexity. An important step toward the controlled formation of a desired superstructure is to identify reversible electrostatic interactions between patches which allow them to align with one another. The formation of bipatchy particles with two oppositely charged patches fabricated using sandwich microcontact printing is reported. These particles spontaneously self-aggregate in solution, where a diversity of short and long chains of bipatchy particles with different shapes, such as branched, bent, and linear, are formed. Calculations show that chain formation is driven by a combination of attractive electrostatic interactions between oppositely charged patches and the charge-induced polarization of interacting particles.

Shaping Metallic Nanolattices: Design by Microcontact Printing from Wrinkled Stamps

A method for the fabrication of well-defined metallic nanostructures is presented here in a simple and straightforward fashion. As an alternative to lithographic techniques, this routine employs microcontact printing utilizing wrinkled stamps, which are prepared from polydimethylsiloxane (PDMS), and includes the formation of hydrophobic stripe patterns on a substrate via the transfer of oligomeric PDMS. Subsequent backfilling of the interspaces between these stripes with a hydroxyl-functional poly(2-vinyl pyridine) then provides the basic pattern for the deposition of citrate-stabilized gold nanoparticles promoted by electrostatic interaction. The resulting metallic nanostripes can be further customized by peeling off particles in a second microcontact printing step, which employs poly(ethylene imine) surface-decorated wrinkled stamps, to form nanolattices. Due to the independent adjustability of the period dimensions of the wrinkled stamps and stamp orientation with respect to the substrate, particle arrays on the (sub)micro-scale with various kinds of geometries are accessible in a straightforward fashion. This work provides an alternative, cost-effective, and scalable surface-patterning technique to fabricate nanolattice structures applicable to multiple types of functional nanoparticles. Being a top-down method, this process could be readily implemented into, e.g., the fabrication of optical and sensing devices on a large scale.

Radiation-Induced Optic Neuropathy: Observation versus Intravitreal Treatment: Can Visual Acuity Be Maintained by Intravitreal Treatment?

PURPOSE

To compare intravitreal therapy with the natural course of radiation optic neuropathy after primary proton beam therapy for choroidal melanoma with respect to long-term visual acuity and development of optic atrophy.

DESIGN

Retrospective comparative case series.

METHODS

Inclusion criteria: patients treated with primary proton beam therapy for choroidal melanoma with a minimum follow-up of 24 months after the occurrence of radiation optic neuropathy and optic disc imaging during follow-up.

EXCLUSION CRITERIA

pathologic condition of the optic disc before irradiation and intravitreal therapy to treat cystoid macular edema not originating from the optic disc.

RESULTS

Of 93 patients, 48 were observed only after radiation optic neuropathy, and 45 were treated with intravitreal therapy (triamcinolone, bevacizumab, and/or dexamethasone). Median follow-up was 55 months (29-187 months); median interval between onset of radiation optic neuropathy and the last patient visit was 34 months (24-125 months). Of 48 observed patients, 41 (85.4%) developed an optic atrophy after a median of 14 months (3-86 months) after radiation optic neuropathy; and of 45 intravitreally treated patients, 34 (75.5%) presented with an optic atrophy after a median of 12.5 months (1-55 months) following optic neuropathy, indicating no statistically significant differences between the groups. Comparing the change in visual acuity from occurrence of optic neuropathy to final visual acuity, no statistically significant differences were found between either group (P = 0.579).

CONCLUSIONS

Patients treated with intravitreal therapy for radiation optic neuropathy showed no statistically significant differences related to visual acuity or optic atrophy development from patients who underwent only observation.

A Biocatalytically Active Membrane Obtained from Immobilization of 2-Deoxy-d-ribose-5-phosphate Aldolase on a Porous Support

Aldol reactions play an important role in organic synthesis, as they belong to the class of highly beneficial C-C-linking reactions. Aldol-type reactions can be efficiently and stereoselectively catalyzed by the enzyme 2-deoxy-d-ribose-5-phosphate aldolase (DERA) to gain key intermediates for pharmaceuticals such as atorvastatin. The immobilization of DERA would open the opportunity for a continuous operation mode which gives access to an efficient, large-scale production of respective organic intermediates. In this contribution, we synthesize and utilize DERA/polymer conjugates for the generation and fixation of a DERA bearing thin film on a polymeric membrane support. The conjugation strongly increases the tolerance of the enzyme toward the industrial relevant substrate acetaldehyde while UV-cross-linkable groups along the conjugated polymer chains provide the opportunity for covalent binding to the support. First, we provide a thorough characterization of the conjugates followed by immobilization tests on representative, nonporous cycloolefinic copolymer supports. Finally, immobilization on the target supports constituted of polyacrylonitrile (PAN) membranes is performed, and the resulting enzymatically active membranes are implemented in a simple membrane module setup for the first assessment of biocatalytic performance in the continuous operation mode using the combination hexanal/acetaldehyde as the substrate.

Biocatalytically active microgels by precipitation polymerization of N-isopropyl acrylamide in the presence of an enzyme

We present a novel protocol for the synthesis of enzymatically active microgels. The protocol is based on the precipitation polymerization of N-isopropylacrylamide (NIPAm) in the presence of an enzyme and a protein binding comonomer. A basic investigation on the influence of different reaction parameters such as monomer concentration and reaction temperature on the microgel size and size distribution is performed and immobilization yields are determined. Microgels exhibiting hydrodynamic diameters between 100 nm and 1 μm and narrow size distribution could be synthesized while about 31-44% of the enzyme present in the initial reaction mixture can be immobilized. Successful immobilization including a verification of enzymatic activity of the microgels is achieved for glucose oxidase (GOx) and 2-deoxy-d-ribose-5-phosphate aldolase (DERA). The thermoresponsive properties of the microgels are assessed and discussed in the light of activity evolution with temperature. The positive correlation of enzymatic activity with temperature for the GOx containing microgel originates from a direct interaction of the enzyme with the PNIPAm based polymer matrix whose magnitude is highly influenced by temperature.

In Situ Monitoring of Membrane Protein Insertion into Block Copolymer Vesicle Membranes and Their Spreading via Potential-Assisted Approach

Synthosomes are polymer vesicles with transmembrane proteins incorporated into block copolymer membranes. They have been used for selective transport in or out of the vesicles as well as catalysis inside the compartments. However, both the insertion process of the membrane protein, forming nanopores, and the spreading of the vesicles on planar substrates to form solid-supported biomimetic membranes have been rarely studied yet. Herein, we address these two points and, first, shed light on the real-time monitoring of protein insertion via isothermal titration calorimetry. Second, the spreading process on different solid supports, namely, SiO₂, glass, and gold, via different techniques like spin- and dip-coating as well as a completely new approach of potential-assisted spreading on gold surfaces was studied. While inhomogeneous layers occur via traditional methods, our proposed potential-assisted strategy to induce adsorption of positively charged vesicles by applying negative potential on the electrode leads to remarkable vesicle spreading and their further fusion to form more homogeneous planar copolymer films on gold. The polymer vesicles in our study are formed from amphiphilic copolymers poly(2-methyl oxazoline)-block-poly(dimethylsiloxane)-block-poly(2-methyl oxazoline) (PMOXA-b-PDMS-b-PMOXA). Engineered variants of the transmembrane protein ferric hydroxamate uptake protein component A (FhuA), one of the largest β-barrel channel proteins, are used as model nanopores. The incorporation of FhuA Δ1-160 is shown to facilitate the vesicle spreading process further. Moreover, high accessibility of cysteine inside the channel was proven by linkage of a fluorescent dye inside the engineered variant FhuA ΔCVF^tev and hence preserved functionality of the channels after spreading. The porosity and functionality of the spread synthosomes on the gold plates have been examined by studying the passive ion transport response in the presence of Li⁺ and ClO₄^- ions and electrochemical impedance spectroscopy analysis. Our approach to form solid-supported biomimetic membranes via the potential-assisted strategy could be important for the development of new (bio-) sensors and membranes.

Temperature-Controlled Solvent Vapor Annealing of Thin Block Copolymer Films

Solvent vapor annealing is as an effective and versatile alternative to thermal annealing to equilibrate and control the assembly of polymer chains in thin films. Here, we present scientific and practical aspects of the solvent vapor annealing method, including the discussion of such factors as non-equilibrium conformational states and chain dynamics in thin films in the presence of solvent. Homopolymer and block copolymer films have been used in model studies to evaluate the robustness and the reproducibility of the solvent vapor processing, as well as to assess polymer-solvent interactions under confinement. Advantages of utilizing a well-controlled solvent vapor environment, including practically interesting regimes of weakly saturated vapor leading to poorly swollen states, are discussed. Special focus is given to dual temperature control over the set-up instrumentation and to the potential of solvo-thermal annealing. The evaluated insights into annealing dynamics derived from the studies on block copolymer films can be applied to improve the processing of thin films of crystalline and conjugated polymers as well as polymer composite in confined geometries.

Mono-patchy zwitterionic microcolloids as building blocks for pH-controlled self-assembly

A directional molecular interaction between microcolloids can be achieved through pre-defined sites on their surface, "patches", which might make them follow each other in a controlled way and assemble into target structures of more complexity. In this article, we report the successful generation and characterization of mono-patchy melamine-formaldehyde microparticles with oppositely charged patches made of poly(methyl vinyl ether-alt-maleic acid) or polyethyleneimine via microcontact printing. The study of their self-aggregation behavior in solution shows that by change of pH, particle dimers are formed via attractive electrostatic force between the patchy and non-patchy surface of the particles, which reaches its optimum at a specific pH.

Broadening the scope of sortagging

Sortases are enzymes occurring in the cell wall of Gram-positive bacteria. Sortase A (SrtA), the best studied sortase class, plays a key role in anchoring surface proteins with the recognition sequence LPXTG covalently to oligoglycine units of the bacterial cell wall. This unique transpeptidase activity renders SrtA attractive for various purposes and motivated researchers to study multiple in vivo and in vitro ligations in the last decades. This ligation technique is known as sortase-mediated ligation (SML) or sortagging and developed to a frequently used method in basic research. The advantages are manifold: extremely high substrate specificity, simple access to substrates and enzyme, robust nature and easy handling of sortase A. In addition to the ligation of two proteins or peptides, early studies already included at least one artificial (peptide equipped) substrate into sortagging reactions - which demonstrates the versatility and broad applicability of SML. Thus, SML is not only a biology-related technique, but has found prominence as a major interdisciplinary research tool. In this review, we provide an overview about the use of sortase A in interdisciplinary research, mainly for protein modification, synthesis of protein-polymer conjugates and immobilization of proteins on surfaces.

Tailoring patches on particles: a modified microcontact printing routine using polymer-functionalised stamps

Herein, we report a modified microcontact printing (μCP) routine suitable to introduce particle patches of a low molecular weight ink (LMWI) on porous SiO2 microparticles. Thereby, patch precision could be significantly improved by utilising stamps which have been surface-functionalised with grafted polymers. This improvement was evaluated by a profound software-assisted statistical analysis.

Characteristics of microcontact printing with polyelectrolyte ink for the precise preparation of patches on silica particles

This publication demonstrates the abilities of a precise and straightforward microcontact printing approach for the preparation of patchy silica particles. In a broad particle size range, it is possible to finely tune the number and parameters of three-dimensional patches like diameter and thickness using only polyethyleneimine ink, poly(dimethoxysilane) as stamp material and a suitable release solvent.

Magnetic Field-Induced Assembly of Superparamagnetic Cobalt Nanoparticles on Substrates and at Liquid-Air Interface

Superparamagnetic cobalt nanoparticles (Co NPs) are an interesting material for self-assembly processes because of their magnetic properties. We investigated the magnetic field-induced assembly of superparamagnetic cobalt nanoparticles and compared three different approaches, namely, the assembly on solid substrates, at water-air, and ethylene glycol-air interfaces. Oleic acid- and trioctylphosphine oxide-coated Co NPs were synthesized via a thermolysis of cobalt carbonyl and dispersed into either hexane or toluene. The Co NP dispersion was dropped onto different substrates (e.g., transmission electron microscopy (TEM) grid, silicon wafer) and onto liquid surfaces. Transmission electron microscopy (TEM), scanning force microscopy, optical microscopy, as well as scanning electron microscopy showed that superparamagnetic Co NPs assembled into one-dimensional chains in an external magnetic field. By varying the concentration of the Co NP dispersion (1-5 mg/mL) and the strength of the magnetic field (4-54 mT), the morphology of the chains changed. Short, thin, and flexible chain structures were obtained at low NP concentration and low strength of magnetic field, whereas they became long, thick and straight when the NP concentration and the magnetic field strength increased. In comparison, the assembly of Co NPs from hexane dispersion at ethylene glycol-air interface showed the most regular and homogeneous alignment, since a more efficient spreading could be achieved on ethylene glycol than on water and solid substrates.

Synthesis of thermo-responsive nanocomposites of superparamagnetic cobalt nanoparticles/poly(N-isopropylacrylamide)

Novel nanocomposites of superparamagnetic cobalt nanoparticles (Co NPs) and poly(N-isopropylacrylamide) (PNIPAM) were fabricated through surface-initiated atom-transfer radical polymerization (SI-ATRP). We firstly synthesized a functional ATRP initiator, containing an amine (as anchoring group) and a 2-bromopropionate group (SI-ATRP initiator). Oleic acid- and trioctylphosphine oxide-coated Co NPs were then modified with the initiator via ligand exchange. The process is facile and rapid for efficient surface functionalization and afterwards the Co NPs can be dispersed into polar solvent DMF without aggregation. Transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and dynamic light scattering measurements confirmed the success of ligand exchange. The following polymerization of NIPAM was conducted on the surface of Co NPs. Temperature-dependent dynamic light scattering study showed the responsive behavior of PNIPAM-coated Co NPs. The combination of superparamagnetic and thermo-responsive properties in these hybrid nanoparticles is promising for future applications e.g. in biomedicine.

[Peripheral Ischemia in Diabetic Retinopathy and Retinal Vein Occlusion: New Insights with Ultra-Wide-Angle Fundus Imaging and Wide-Angle Fluorescein Angiography]

BACKGROUND

In several diseases such as diabetic retinopathy and retinal vein occlusion, relevant pathophysiological changes take place in the retinal periphery. These changes may determine the prognosis and outcomes of therapy. Recent ultra-wide-angle camera systems promise improved and simplified visualisation of the outer periphery of the retina. This could potentially lead to novel clinical applications of these methods, with potential impact on therapy decisions.

MATERIAL AND METHODS

Literature and database research on ultra-wide imaging for diabetic retinopathy and retinal vein occlusion.

RESULTS

With ultra-wide-angle angiography, it is possible to visualise up to 3.2-fold more retinal surface than conventional 7SF images (7SF: 7 standard field). Initial studies imply that diabetic changes can be found outside of the boundaries of the 7SF images. Patients with central vein occlusion have more extended and severe macular oedema and poorer visual acuity if ischemia of the periphery is more pronounced (measured by the ischemic index [ISI]). The amount of ischemia influences the size of the macular oedema, its resolution under therapy and the number of anti-VEGF injections needed to treat it.

DISCUSSION

Ultra-wide-angle camera systems allow visualisation of the peripheral retina outside the boundaries of standard methods. Initial studies have detected potentially relevant changes in the outer periphery, which would have been missed by 7SF. Nevertheless, there have been no systematic studies on the relevance of these changes with regards to prognosis and therapeutic decisions.

Proton Beam Irradiation: A Safe Procedure in Postequatorial Extraocular Extension From Uveal Melanoma

PURPOSE

This study was performed to show long-term outcomes concerning metastasis rates and local recurrence rates after primary proton beam therapy in uveal melanoma with posterior extraocular extension (EOE) with the main focus on optic nerve invasion.

DESIGN

Retrospective case series.

METHODS

All patients treated with primary proton beam therapy for choroidal or ciliary body melanoma with posterior EOE between July 1998 and August 2010 were included. EOE was detected either upon sonography at primary examination or during the surgical application of tantalum clips onto the sclera. Ultrasound was performed in each patient before surgery, and if EOE was detected, a magnetic resonance imaging (MRI) scan was performed to confirm EOE. All patients with tumors exceeding 6 mm in thickness or abutting the optic disc received a 1.5 Tesla MRI scan after clip surgery. To assess EOE during follow-up, either ultrasound examinations or-if initially detected only by MRI-MRI scans were performed during follow-up.

RESULTS

A total of 27 patients underwent primary proton beam therapy. The EOE was separated into 3 growth types: optic nerve infiltration in 10 patients, vortex vein infiltration in 9 patients, and transscleral growth postequatorially in 8 patients. No local recurrences were found during the overall median follow-up of 80 months (11-168 months). Metastasis rates correlated with AJCC stages but not EOE volume.

CONCLUSION

This study shows that posterior EOE can safely be treated by proton beam therapy, even if the optic nerve is infiltrated. MRI enables safe detection of optic nerve invasion.

Generation of 3-dimensional multi-patches on silica particles via printing with wrinkled stamps

A simple route towards patchy particles with anisotropic patches with respect to a different functionality and directionality is presented. This method is based on microcontact printing of positively charged polyethylenimine (PEI) on silica particles using wrinkled stamps. Due to the wrinkled surface, the number of patches on the particles as well as the distance between two patches can be controlled.

From 2D to 3D patches on multifunctional particles: how microcontact printing creates a new dimension of functionality

A straightforward approach for the precise multifunctional surface modification of particles with three-dimensional patches using microcontact printing is presented. By comparison to previous works it was possible to not only control the diameter, but also to finely tune the thickness of the deposited layer, opening up the way for three-dimensional structures and orthogonal multifunctionality. The use of PEI as polymeric ink, PDMS stamps for microcontact printing on silica particles and the influence of different solvents during particle release on the creation of functional particles with three-dimensional patches are described. Finally, by introducing fluorescent properties by incorporation of quantum dots into patches and by particle self-assembly via avidin-biotin coupling, the versatility of this novel modification method is demonstrated.

Physical Polyurethane Hydrogels via Charge Shielding through Acids or Salts

Physical hydrogels with tunable stress-relaxation and excellent stress recovery are formed from anionic polyurethanes via addition of acids, monovalent salts, or divalent salts. Gel properties can be widely adjusted through pH, salt valence, salt concentration, and monomer composition. We propose and investigate a novel gelation mechanism based on a colloidal system interacting through charge repulsion and chrage shielding, allowing a broad use of the material, from acidic (pH 4-5.5) to pH-neutral hydrogels with Young's moduli ranging from 10 to 140 kPa.

Biocatalytically Active Thin Films via Self-Assembly of 2-Deoxy-d-ribose-5-phosphate Aldolase-Poly(N-isopropylacrylamide) Conjugates

2-Deoxy-d-ribose-5-phosphate aldolase (DERA) is a biocatalyst that is capable of converting acetaldehyde and a second aldehyde as acceptor into enantiomerically pure mono- and diyhydroxyaldehydes, which are important structural motifs in a number of pharmaceutically active compounds. However, substrate as well as product inhibition requires a more-sophisticated process design for the synthesis of these motifs. One way to do so is to the couple aldehyde conversion with transport processes, which, in turn, would require an immobilization of the enzyme within a thin film that can be deposited on a membrane support. Consequently, we developed a fabrication process for such films that is based on the formation of DERA-poly(N-isopropylacrylamide) conjugates that are subsequently allowed to self-assemble at an air-water interface to yield the respective film. In this contribution, we discuss the conjugation conditions, investigate the interfacial properties of the conjugates, and, finally, demonstrate a successful film formation under the preservation of enzymatic activity.

Nano-thin walled micro-compartments from transmembrane protein-polymer conjugates

The high interfacial activity of protein-polymer conjugates has inspired their use as stabilizers for Pickering emulsions, resulting in many interesting applications such as synthesis of templated micro-compartments and protocells or vehicles for drug and gene delivery. In this study we report, for the first time, the stabilization of Pickering emulsions with conjugates of a genetically modified transmembrane protein, ferric hydroxamate uptake protein component A (FhuA). The lysine residues of FhuA with open pore (FhuA ΔCVF^tev) were modified to attach an initiator and consequently controlled radical polymerization (CRP) carried out via the grafting-from technique. The resulting conjugates of FhuA ΔCVF^tev with poly(N-isopropylacrylamide) (PNIPAAm) and poly((2-dimethylamino)ethyl methacrylate) (PDMAEMA), the so-called building blocks based on transmembrane proteins (BBTP), have been shown to engender larger structures. The properties such as pH-responsivity, temperature-responsivity and interfacial activity of the BBTP were analyzed using UV-Vis spectrophotometry and pendant drop tensiometry. The BBTP were then utilized for the synthesis of highly stable Pickering emulsions, which could remain non-coalesced for well over a month. A new UV-crosslinkable monomer was synthesized and copolymerized with NIPAAm from the protein. The emulsion droplets, upon crosslinking of polymer chains, yielded micro-compartments. Fluorescence microscopy proved that these compartments are of micrometer scale, while cryo-scanning electron microscopy and scanning force microscopy analysis yielded a thickness in the range of 11.1 ± 0.6 to 38.0 ± 18.2 nm for the stabilizing layer of the conjugates. Such micro-compartments would prove to be beneficial in drug delivery applications, owing to the possibility of using the channel of the transmembrane protein as a gate and the smart polymer chains as trigger switches to tune the behavior of the capsules.