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Chlamydia psittaciis an avian bacterial pathogen that can cause atypical pneumonia in humans via zoonotic transmission. It is a Gram-negative intracellular bacterium that proliferates inside membrane bound inclusions in the cytoplasm of living eukaryotic cells. The study of such cells with C. psittaciinside without destroying them poses a significant challenge. We demonstrated in this work the utility of a combined multitool approach to analyze such complex samples. Atomic force microscopy was applied to obtain high-resolution images of the surface of infected cells upon entrance of bacteria. Atomic force microscopy scans revealed the morphological changes of the cell membrane of Chlamydiainfected cells such as changes in roughness of cell membrane and the presence of micro vesicles. 4Pi Raman microscopy was used to image and probe the molecular composition of intracellular bacteria inside intact cells. Information about the structure of the inclusion produced by C. psittaciwas obtained and it was found to have a similar molecular fingerprint as that of an intracellular lipid droplet but with less proteins and unsaturated lipids. The presented approach demonstrates complementarity of various microscopy-based approaches and might be useful for characterization of intracellular bacteria.

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Piezoelectric poly-L-lactide (PLLA) is a biodegradable polymer used in various biomedical applications. However, tailoring and controlling the structure of PLLA to enhance its piezoelectric response remains a challenge. In this work, extensive characterization was performed to reveal the effect of the reduced graphene oxide (rGO) content (0.2, 0.7, and 1.0 wt%) on the morphology, structure, thermal and piezoelectric behavior of PLLA scaffolds. Randomly oriented homogeneous fibers and a quasi-amorphous structure for pure PLLA and hybrid PLLA-rGO scaffolds were revealed. The addition of rGO affected the molecular structure of the PLLA scaffolds: for example, the number of polar C=O functional groups was increased. Increasing the content of rGO to 1 wt% resulted in decreased glass transition and melting temperatures and increased the degree of crystallinity of the scaffolds. The addition of 0.2 wt% rGO enhanced the effective local vertical and lateral piezoresponses by 2.3 and 15.4 times, respectively, in comparison with pure PLLA fibers. The presence of the shear piezoelectric α-phase (P212121) in uniaxially oriented PLLA fibers and C=O bond rotation in the polymer chains explained the observed piezoresponse. Thus, this study revealed routes to prepare hybrid biodegradable scaffolds with enhanced piezoresponse for tissue engineering applications.

Developing materials for tissue engineering and studying the mechanisms of cell adhesion is a complex and multifactor process that needs analysis using physical chemistry and biology. The major challenge is the labor-intensive data mining as well as requirements of the number of advanced techniques. For example, hydrogel-based biomaterials with cell-binding sites, tunable mechanical properties, and complex architectures have emerged as a powerful tool to control cell adhesion and proliferation for tissue engineering. Composite hydrogels could be used for bone tissue regeneration, but they exhibit poor ossification properties. In current work, we have designed new osteoinductive gellan gum hydrogels by a thermal annealing approach and consequently functionalized them with Ca/Mg carbonate submicron particles. Determination of key parameters, which influence a successful hydroxyapatite generation, was done via the principal component analysis of 18 parameters (Young’s modulus of the hydrogel and particles, particle size, and mass) and cell behavior at various time points (like viability, numbers of the cells, rate of alkaline phosphatase production, and cells area) obtained by characterizing such composite hydrogel. It is determined that the particles size and concentration of calcium ions have a dominant effect on the hydroxyapatite formation, because of providing local areas with a high Young’s modulus in a hydrogel, a desirable property for cell adhesion. The detailed analysis presented here allows identifying hydrogels for cell growth applications, while on the other hand, material properties can be predicted, and their overall number can be minimized leading to efficient optimization of bone reconstruction and other cell growth applications.

Biomaterials engineered with specific cell binding sites, tunable mechanical properties, and complex architectures are essential to control cell adhesion and proliferation. The influence of the local properties, such as the local hardness and stability on the interaction with cells, has not been yet fully understood and exploited. This is particularly relevant for hydrogels, very promising materials with, unfortunately, poor cell adhesion properties, attributed mostly to their softness. Here, we propose a new approach for producing hybrid hydrogels by functionalizing them with particles and performing a thermal treatment. Exploring the interaction of cells with these materials we introduce a new concept, cells-grabbing-onto-particles, a facilitation of the cell adhesion through modulation of local properties. The approach is implemented on alginate hydrogels typically unsuitable for cell growth by turning them into a very effective cell culture growth platform. Specifically, alginate hydrogels are bio-mineralized with calcium carbonate (CaCO3) particles, where an additional thermal annealing (T-A) process has been applied. The local Young’s modulus of new T-A treated hybrid hydrogels has increased to over 3 MPa on areas of hydrogels containing particles and to around 1 MPa on areas without particles, which is drastically different from 130 to 180 kPa values for unmodified hydrogels. Intriguingly, our results show that enhancement of local mechanical properties alone is a necessary, but insufficient, condition; the particles must be stably fixed in gels for cell growth and proliferation. Extended for hydrogels functionalized with silica particles too, the cells-grab-on-particles concept is shown applicable to different materials and cells for cell biology and tissue engineering.

2,2′-Bipyridine is the most widely used chelating ligand for developing metal complexes in coordination and supramolecular chemistry. Here, we present a series of three bipyridine periodic mesoporous organosilicas (BPy-PMOs) grafted with lanthanide β-diketonate complex for the purpose of obtaining thermochromic materials, which can be employed as ratiometric temperature sensors. Such thermometers are based on the ratio of two emission intensity peaks and are not affected by factors such as alignment or optoelectronic drift of the excitation source and detectors. Three thermometric systems are studied: Dy–Dy, Tb–Sm, and Tb–Eu with the first two showing very attractive performance. For the first two systems, some of the best reported to date relative sensitivities are observed. In the BPy-PMO@Dy(acac)3system, it is very unusual that the 4I15/2→ 6H15/2transition is already occupied at low temperature such as 200 K, which influences its thermometric behavior. The Tb–Sm shows excellent performance in the physiological range and when suspended in water. We have additionally confirmed that the BPy-PMO hybrid materials lack toxicity to human cells, proving them very promising candidates for biomedical thermometric applications.

The plasma polymerization of amide-based precursors is a nearly unexplored research area, which is in contrast with the abundance of reports focusing on amide-based surface modification using wet chemistry. Therefore, this study aims to profoundly investigate the near-atmospheric pressure plasma polymerization of N,N-dimethylacrylamide (DMAM) to obtain stable coatings. In contrast to the unstable coatings obtained at lower discharge powers, the stable coatings that were obtained at higher powers showed a lower hydrophilicity as assessed by water contact angle (WCA). This decrease in hydrophilicity with increasing plasma power was found to be related to a reduced preservation of the monomer structure, as observed by Fourier transform infrared (FTIR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and XPS C60depth profiling, a rarely used but effective combination of techniques. Furthermore, the chemical composition of the coating was found to be in good agreement with the plasma active species observed by optical emission spectroscopy. Additionally, XPS C60depth profiling indicated a difference between the top layer and bulk of the plasma polymer due to spontaneous oxidation and/or postplasma coating deposition. Finally, the stable coatings were also found to have cell-interactive behavior toward MC3T3 as studied by in vitro live/dead fluorescence imaging and (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) (MTS) assays. With the latter technique, a cell viability of up to 89% as compared with tissue culture plates after 1 day of cell culture was observed, indicating the potential of these coatings for tissue engineering purposes.

Hydrogels, which are versatile three-dimensional structures containing polymers and water, are very attractive for use in biomedical fields, but they suffer from rather weak mechanical properties. In this regard, biocompatible particles can be used to enhance their mechanical properties. The possibility of loading such particles with drugs (e.g. enzymes) makes them a particularly useful component in hydrogels. In this study, micro/nanoparticles containing various ratios of Ca2+/Mg2+with sizes ranging from 1 to 8 μm were prepared and mixed with gellan gum (GG) solution to study the in-situ formation of hydrogel-particle composites. The particles provide multiple functionalities: 1) they efficiently crosslink GG to induce hydrogel formation through the release of the divalent cations (Ca2+/Mg2+) known to bind to GG polymer chains; 2) they enhance mechanical properties of the hydrogel from 2 up to 100 kPa; 3) the samples most efficiently promoting cell growth were found to contain two types of minerals: vaterite and hydroxymagnesite, which enhanced cells proliferation and hydroxyapatite formation. The results demonstrate that such composite materials are attractive candidates for applications in bone regeneration.

Exosome-like vesicles (ELVs) are nanovectors released by cells that are endowed with a variety of molecules, including proteins, nucleic acids, and chemicals that reflect the molecular signature of the producing cell. Given their presence in many biofluids, they form an easily accessible biomarker for early disease detection. Previously we demonstrated the possibility of identifying individual ELVs by analyzing their molecular signatures with surface-enhanced Raman scattering (SERS) after functionalization of ELVs with 4-(dimethylamino)pyridine (DMAP)-stabilized gold nanoparticles (AuNP). Although this strategy was capable of distinguishing ELVs from different cellular origins, the quality of the SERS spectra was suboptimal due to high background coming from the DMAP stabilizing molecules at the AuNP surface. In this study we demonstrate that it is possible to eliminate interfering SERS signals from stabilizing molecules at the AuNP surface by overgrowing in situthe ELV-attached AuNPs with a silver layer so as to form a core–shell nanoparticle (Au@AgNPs) directly at the ELV surface. As such it represents the first known strategy to generate clear SERS spectral fingerprints of delicate biological structures without interference of linker molecules that are needed to ensure colloidal stability of the plasmonic NP and to allow them to associate to the ELV surface. This new strategy using core–shell plasmonic NPs as SERS substrate showed higher near-field enhancements than previous approaches, which resulted in SERS spectra with improved signal-to-noise ratio. This allowed us to discriminate individual vesicles derived from B16F10 melanoma cells and red blood cells (RBC) with an unprecedented sensitivity and specificity >90%. Importantly, thanks to the higher near field enhancement the acquisition time could be reduced by 20-fold in comparison to previously reported strategies, paving the way toward high-throughput label-free single ELV identification.

The importance of thermodynamics does not need to be emphasized. Indeed, elevated temperature processes govern not only industrial scale production but also self-assembly, chemical reaction, interaction between molecules, etc. Not surprisingly, biological processes typically take place at a specific temperature. Here, we look at possibilities to raise the localized temperature by a laser around noble-metal nanoparticles incorporated into shells of layer-by-layer polyelectrolyte microcapsules—freely suspended delivery vehicles in an aqueous solution, developed in the Department of Interfaces, Max Planck Institute of Colloids and Interfaces, headed by Helmuth Möhwald. Understanding the mechanisms of localized temperature rise is essential, that is why we analyze the influence of incident intensity, nanoparticle size, their distribution and aggregation state, as well as thermodynamics at the nanoscale. This leads us to scrutinize “global” (used for thermal encapsulation) versus “local” (used for release of encapsulated materials) temperature rise. Similar analysis is extended to planar polymeric coatings, the lipid membrane system of vesicles and cells, on which nanoparticles are adsorbed. Insights are provided into the mechanisms of physicochemical and biological effects, the nature of which has always been profoundly, interactively, and engagingly discussed in the Department of Interfaces. This analysis is combined with recent developments providing outlook and highlighting a broad range of emerging applications.

Layer-by-layer (LbL) assembly is a widely used tool for engineering materials and coatings. In this Perspective, dedicated to the memory of ACS Nanoassociate editor Prof. Dr. Helmuth Möhwald, we discuss the developments and applications that are to come in LbL assembly, focusing on coatings, bulk materials, membranes, nanocomposites, and delivery vehicles.

The deposition of nanosize and microsize spherical particles on planar solid substrates by hydrodynamic-evaporative spin-casting is studied. The particles are dispersed in a volatile liquid, which evaporates during the process, and the particles are finally deposited on the substrate. Their coverage, Γ, depends on the processing parameters (concentration by weight, particles size, etc.). The behavior of the particles during the spin-casting process and their final Γ values are investigated. It is found that for up to particle diameters of a few micrometers, particle deposition can be described by a theoretical approach developed for the spin-casting of polymer solutions (Karpitschka, S.; Weber, C. M.; Riegler, H. Chem. Eng. Sci.2015, 129, 243–248. Danglad-Flores, J.; Eickelmann, S.; Riegler, H. Chem. Eng. Sci.2018, 179, 257–264). For large particles, this basic theory fails. The causes of this failure are analyzed, and a corrected, more general theoretical approach is presented. It takes into account particle size effects as well as particle sedimentation. In summary, we present new insights into the spin-cast process of particle dispersions, analyze the contributions affecting the final particle coverage, and present a theoretical approach which describes and explains the experimental findings.

The importance of the clearance of dead cells is shown to have a regulatory role for normal tissue homeostasis and for the modulation of immune responses. However, how mechanobiological properties of dead cells affect efferocytosis remains largely unknown. Here, it is reported that the Young's modulus of cancer cells undergoing ferroptosis is reduced. To modulate their Young's modulus a layer‐by‐layer (LbL) nanocoating is developed. Scanning electron and fluorescence microscopy confirm coating efficiency of ferroptotic cells while atomic force microscopy reveals encapsulation of the dead cells increases their Young's modulus dependent on the number of applied LbL layers which increases their efferocytosis by primary macrophages. This work demonstrates the crucial role of mechanobiology of dead cells in regulating their efferocytosis by macrophages which can be exploited for the development of novel therapeutic strategies for diseases where modulation of efferocytosis can be potentially beneficial and for the design of drug delivery systems for cancer therapy. In this work, the effect of changing the mechanical properties of ferroptotic cells on the efferocytosis process by macrophages is investigated. By applying layer‐by‐layer coating on the ferroptotic cells using polyelectrolytes, a significant increase in cellular Young's modulus can be achieved. These changes in mechanical properties caused by coating result in an increase of efferocytosis of ferroptotic cells by macrophages.

Immunogenic Cell Death By coating dying tumor cells, represented by the blue mesh around the red cell, the mechanical properties of the dying cells are changed. These properties are measured using atomic force microscopy here represented with the cantilever, laser and quadrant diode. This changing of the mechanical properties affects the interaction with macrophages, here represented by the green cell which is engulfing the coated cell. This work is found in article 2301025by Louis Van der Meeren, Andre G. Skirtach, and co‐workers.

Targeted cell delivery viamagnetically sensitive microcapsules of an applied magnetic field would advance localized cell transplantation therapy, by which healthy cells can be introduced into tissues to repair damaged or diseased organs. In the present research, we implement magnetically sensitive cells viaan uptake of microcapsules containing magnetic nanoparticles in their walls. As is shown in an example of the MA-104 cell line, the magnetic polyelectrolyte multilayer capsules have no toxicity effect on the cells after internalization. Microscopy methods have been used to evaluate the uptake of capsules by the cells. Magnetically sensitive cells are retained in the capillary flow when the magnetic gradient field is applied (<200 T m−1), but they proliferate at the site of retention for several days after the magnet is removed. As an example of cell manipulation, we have demonstrated a novel methodology for cell sheet isolation and transfer using cells impregnated with magnetic microcapsules. A weak enzyme treatment is used to facilitate tissue engineering assemblies by cell monolayer deposition. This type of cell monolayer assembly has provided a 3D tissue engineering construction using an externally applied magnetic field, which is modelled in this study. The approach presented in this work opens perspectives for preclinical studies of tissue and organ repair.

The advent of 4π microscopy broke the conventional optical resolution limit in the axial direction of the microscope. In combination with fluorescence microscopy, it broadened the knowledge of cell biology at the expense of perturbing the samples with extrinsic fluorescent labels. In contrast, Raman microscopy acquires the molecular fingerprint of the sample without the need of extrinsic labels, and therefore improving its resolution can make an even greater impact. Here, we take advantage of the improved axial resolution of a 4π configuration to form a 4π Raman microscope. With this microscope, we independently and simultaneously analyzed different nanolayers in a multilayer stack. We identified their chemical composition and retrieved their relative subwavelength optical separation with a precision of 6 nm.

We have designed multifunctional silver alginate hydrogel microcontainers referred to as loaded microcapsules with different sizes by assembling them via a template assisted approach using natural, highly porous calcium carbonate cores. Sodium alginate was immobilized into the pores of calcium carbonate particles of different sizes followed by cross-linking via addition of silver ions, which had a dual purpose: on one hand, the were used as a cross-linking agent, albeit in the monovalent form, while on the other hand they have led to formation of silver nanoparticles. Monovalent silver ions, an unusual cross-linking agent, improve the sensitivity to ultrasound, lead to homogeneous distribution of silver nanoparticles. Silver nanoparticles appeared on the shell of the alginate microcapsules in the twin-structure as determined by transmission electron microscopy. Remote release of a payload from alginate containers by ultrasound was found to strongly depend on the particle size. The possibility to use such particles as a platform for label-free molecule detection based on the surface enhanced Raman scattering was demonstrated. Cytotoxicity and cell uptake studies conducted in this work have revealed that microcontainers exhibit nonessential level of toxicity with an efficient uptake of cells. The above-described functionalities constitute building blocks of a theranostic system, where detection and remote release can be achieved with the same carrier.

The design and use of materials in the nanoscale size range for addressing medical and health-related issues continues to receive increasing interest. Research in nanomedicine spans a multitude of areas, including drug delivery, vaccine development, antibacterial, diagnosis and imaging tools, wearable devices, implants, high-throughput screening platforms, etc.using biological, nonbiological, biomimetic, or hybrid materials. Many of these developments are starting to be translated into viable clinical products. Here, we provide an overview of recent developments in nanomedicine and highlight the current challenges and upcoming opportunities for the field and translation to the clinic.

This is the first comprehensive study of the impact of biodegradation on the structure, surface potential, mechanical and piezoelectric properties of poly(3‐hydroxybutyrate) (PHB) scaffolds supplemented with reduced graphene oxide (rGO) as well as cell behavior under static and dynamic mechanical conditions. There is no effect of the rGO addition up to 1.0 wt% on the rate of enzymatic biodegradation of PHB scaffolds for 30 d. The biodegradation of scaffolds leads to the depolymerization of the amorphous phase, resulting in an increase in the degree of crystallinity. Because of more regular dipole order in the crystalline phase, surface potential of all fibers increases after the biodegradation, with a maximum (361 ± 5 mV) after the addition of 1 wt% rGO into PHB as compared to pristine PHB fibers. By contrast, PHB‐0.7rGO fibers manifest the strongest effective vertical (0.59 ± 0.03 pm V−1) and lateral (1.06 ± 0.02 pm V−1) piezoresponse owing to a greater presence of electroactive β‐phase. In vitro assays involving primary human fibroblasts reveal equal biocompatibility and faster cell proliferation on PHB‐0.7rGO scaffolds compared to pure PHB and nonpiezoelectric polycaprolactone scaffolds. Thus, the developed biodegradable PHB‐rGO scaffolds with enhanced piezoresponse are promising for tissue‐engineering applications. This work reveals the advantages of biodegradable piezoelectric polymer‐based materials for tissue‐engineering applications. The addition of reduced graphene oxide nanoflakes into electrospun poly(3‐hydrobutyrate) fibrous scaffolds allows a significant increase in both surface potential and piezoresponse, without any alteration of their biodegradation rate. The enhanced piezoresponse provides the improved cell proliferation on the surface of hybrid scaffolds.

There is a great interest in delivering macromolecular agents into living cells for therapeutic purposes, such as siRNA for gene silencing. Although substantial effort has gone into designing nonviral nanocarriers for delivering macromolecules into cells, translocation of the therapeutic molecules from the endosomes after endocytosis into the cytoplasm remains a major bottleneck. Laser-induced photoporation, especially in combination with gold nanoparticles, is an alternative physical method that is receiving increasing attention for delivering macromolecules in cells. By allowing gold nanoparticles to bind to the cell membrane, nanosized membrane pores can be created upon pulsed laser illumination. Depending on the laser energy, pores are created through either direct heating of the AuNPs or by vapor nanobubbles (VNBs) that can emerge around the AuNPs. Macromolecules in the surrounding cell medium can then diffuse through the pores directly into the cytoplasm. Here we present a systematic evaluation of both photoporation mechanisms in terms of cytotoxicity, cell loading, and siRNA transfection efficiency. We find that the delivery of macromolecules under conditions of VNBs is much more efficient than direct photothermal disturbance of the plasma membrane without any noticeable cytotoxic effect. Interestingly, by tuning the laser energy, the pore size could be changed, allowing control of the amount and size of molecules that are delivered in the cytoplasm. As only a single nanosecond laser pulse is required, we conclude that VNBs are an interesting photoporation mechanism that may prove very useful for efficient high-throughput macromolecular delivery in live cells.

Introduction:Red blood cells (RBCs) and lipid-based carriers on the one hand and polymeric capsules on the other hand represent two of the most widely used carriers in drug delivery. Each class of these carriers has its own set of properties, specificity and advantages. Thorough comparative studies of such systems are reported here for the first time.Areas covered:In this review, RBCs are described in comparison with synthetic polymeric drug delivery vehicles using polyelectrolyte multilayer capsules as an example. Lipid-based composition of the shell in the former case is particularly attractive due to their inherent biocompatibility and flexibility of the carriers. On the other hand, synthetic approaches to fabrication of polyelectrolyte multilayer capsules permit manipulation of the permeability of their shell as well as tuning their composition, mechanical properties, release methods and targeting.Expert Opinion:In conclusion, properties of RBCs and polyelectrolyte multilayer capsules are reported here highlighting similarities and differences in their preparation and applications. In addition, their advantages and disadvantages are discussed.

We report on the selective cell detachment from nanoengineered gold nanoparticle (AuNP) surfaces triggered by laser irradiation, which occurs in a nonthermal manner. The gold nanoparticle-based surfaces reveal good adhesion of NIH3T3 fibroblast cells. Patterning is achieved by lithographic microcontact printing, selective gold nanoparticle deposition, and by laser beam profiling. It is shown that the effectiveness of fibroblast cell detachment depends on the cell age, laser power, and AuNP patterning profile. Heat distribution and temperature rise around gold nanoparticle functionalized surfaces is modeled, revealing low heating of nanoparticles by laser illumination. The nonthermal photochemical mechanism of cell detachment due to production of reactive oxygen species under illumination of gold nanoparticles by green laser light is studied. We also demonstrate that cells migrate from unirradiated areas leading to their reattachment and surface recovery which is important for controlled spatial organization of cells in wound healing and tissue engineering. Research presented in this work is targeted at designing biointerfaces for cell cultures.

A nanoplasmonics-based opto-nanoporation method of creating nanopores upon laser illumination is applied for inducing diffusion and triggered release of small and large molecules from red blood cells (RBCs). The method is implemented using absorbing gold nanoparticle (Au-NP) aggregates on the membrane of loaded RBCs, which, upon near-IR laser light absorption, induce release of encapsulated molecules from selected cells. The binding of Au-NPs to RBCs is characterized by Raman spectroscopy. The process of release is driven by heating localized at nanoparticles, which impacts the permeability of the membrane by affecting the lipid bilayer and/or trans-membrane proteins. Localized heating and temperature rise around Au-NP aggregates is simulated and discussed. Research reported in this work is relevant for generating nanopores for biomolecule trafficking through polymeric and lipid membranes as well as cell membranes, while dual- and multi-molecule release is relevant for theragnostics and a wide range of therapies.

Direction‐specific release induced through osmotic pressure inside giant microcapsules is realized and monitored at high and low concentrations of encapsulated polymer. A clear correlation between the release kinetics upon opening the shell and encapsulated polymer concentration is observed. This has been independently confirmed by shell opening via nanoindentation and laser radiation. To quantify these observations, the internal pressure of the capsules is determined by analysis of mechanical tests performed via colloidal probe AFM. As expected, larger amounts of encapsulated material lead to increased internal pressures and enhanced release kinetics. The results show how drug release can be accelerated by encapsulation of osmotic pressure generating species. Such pressurized capsules systems show large ejection velocities and are envisioned as an inexpensive biolistic transfection device for in vitro applications.

Breaking out: Liposomes that are adsorbed onto porous CaCO3particles and that contain the peroxidase substrate Amplex Red (AR) are disrupted by ultrasonic treatment. The substrate is released and diffuses into the inner part of the multicompartment containers where the peroxidase enzyme is found, and the enzymatic reaction is triggered. This approach may be useful for the simultaneous delivery of multiple molecules into cells.

Raus aus dem Käfig, rein in die Reaktion: Liposomen, die auf porösen CaCO3‐Partikeln adsorbiert sind und das Peroxidase‐Substrat Amplex Red (AR) enthalten, brechen bei Ultraschallbehandlung auf und setzen das Substrat frei; dieses diffundiert ins Innere des Multikompartimentbehälters, der das Enzym Peroxidase enthält, und setzt die enzymatische Reaktion in Gang. Dieses Verfahren könnte zum gleichzeitigen Einschleusen von mehreren Molekülen in Zellen nützlich sein.

Single‐wall carbon nanotubes modified by anionic polyelectrolyte molecules are embedded into the shells of microcapsules. Carbon nanotubes serve as rigid rods in a softer polymeric capsule, which forms a free‐standing shell upon treatment with glutaraldehyde and subsequent drying. The embedded carbon nanotubes exhibit a broad absorption in the UV–near‐infrared part of the spectrum, and that allows point‐wise activation and opening of the microcapsules by laser. Raman signal analysis shows changes of carbon‐nanotube‐specific lines after high‐power laser irradiation, which is characteristic of the formation of disordered carbonlike structures. These polyelectrolyte/carbon nanotube composite capsules represent a novel light‐addressable type of microcontainers.

We introduce a novel and versatile approach to the corrosion protection by use of “smart” laser-controllable coating. The main advantage of the proposed technique is that one could terminate the corrosion process by very intensive healing after an appearance of corrosion centers using local laser irradiation. It is also shown that by applying a polyelectrolyte shell with noble metal particles over the mesoporous titania and silica vialayer-by-layer assembly it is possible to fabricate micro- and nanoscaled reservoirs, which, being incorporated into the zirconia−organosilica matrix, are responsible for the ability of laser-driven release of the loaded materials (e.g., corrosion inhibitor). Furthermore, the resultant films are highly adhesive and could be easily deposited onto different metallic substrates. Laser-mediated remote release of incorporated corrosion inhibitor (benzotriazole) from engineered mesoporous containers with silver nanoparticles in the container shell is observed in real time on single and multicontainer levels.

A novel method of macromolecule encapsulation using micron‐sized polymeric shells constructed with a photoactive azobenzene containing polyelectrolyte is discussed. Fluorescently labeled dextran molecules were encapsulated using light to remotely shrink and change the wall permeability of new polymeric hollow shells. We observed that the proportion of shells with dye encapsulated increased along with the duration of irradiation. Electron microscopy imaging illustrated significant changes in the surface roughness of shells after being exposed to light. Finally, this new system was shown to possess a high thermal stability.

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Piezoelectricity is considered to be one of the key functionalities in biomaterials to boost bone tissue regeneration, however, integrating biocompatibility, biodegradability and 3D structure with pronounced piezoresponse remains a material challenge. Herein, novel hybrid biocompatible 3D scaffolds based on biodegradable poly(3-hydroxybutyrate) (PHB) and reduced graphene oxide (rGO) flakes have been developed. Nanoscale insights revealed a more homogenous distribution and superior surface potential values of PHB fibers (33 ± 29 mV) with increasing rGO content up to 1.0 wt% (314 ± 31 mV). The maximum effective piezoresponse was detected at 0.7 wt% rGO content, demonstrating 2.5 and 1.7 times higher out-of-plane and in-plane values, respectively, than that for pure PHB fibers. The rGO addition led to enhanced zigzag chain formation between paired lamellae in PHB fibers. In contrast, a further increase in rGO content reduced the α-crystal size and prevented zigzag chain conformation. A corresponding model explaining structural and molecular changes caused by rGO addition in electrospun PHB fibers is proposed. In addition, finite element analysis revealed a negligible vertical piezoresponse compared to lateral piezoresponse in uniaxially oriented PHB fibers based on α-phase (P212121space group). Thus, the present study demonstrates promising results for the development of biodegradable hybrid 3D scaffolds with an enhanced piezoresponse for various tissue engineering applications.

•Cells are coated in a hybrid coating using polyelectrolytes and Au-nanoparticles using the LbL-method.•Au-nanoparticles were visualized by AFM and their concentration was determined using absorption spectrophotometry.•LBL-coating of the cells is verified using microscopy revealing a strong coverage.•Using a PrestoBlue assay, the viability of coated cells is confirmed.•Near-infrared laser is used to induce immediate drastic changes in the cellular membrane.

Review: 122 refs.

Cover:Optically‐adressable polymeric microshells made principally of poly(allylamine hydrochloride) and of an azobenzene‐containing polyelectrolyte (PAzo) were produced using the layer‐by‐layer assembly technique. In water, these hollow containers are permeable to labeled polymers. However, by irradiating the loaded capsules with a light source of sufficient intensity, the former shrink and become impermeable to the dye. The supernatant may then be removed and the microshells along with their encapsulated material resuspended in water. Further details can be found in the article by M. Bédard,*A. G. Skirtach, G. B. Sukhorukov on page 1517.