Persistent Room Temperature Phosphorescence from Triarylboranes: A Combined Experimental and Theoretical Study

Achieving highly efficient phosphorescence in purely organic luminophors at room temperature remains a major challenge due to slow intersystem crossing (ISC) rates in combination with effective non‐radiative processes in those systems. Most room temperature phosphorescent (RTP) organic materials have O‐ or N‐lone pairs leading to low lying (n, π*) and (π, π*) excited states which accelerate k_isc through El‐Sayed's rule. Herein, we report the first persistent RTP with lifetimes up to 0.5 s from simple triarylboranes which have no lone pairs. RTP is only observed in the crystalline state and in highly doped PMMA films which are indicative of aggregation induced emission (AIE). Detailed crystal structure analysis suggested that intermolecular interactions are important for efficient RTP. Furthermore, photophysical studies of the isolated molecules in a frozen glass, in combination with DFT/MRCI calculations, show that (σ, B p)→(π, B p) transitions accelerate the ISC process. This work provides a new approach for the design of RTP materials without (n, π*) transitions.     

Microwave-Assisted Azide-Alkyne Cycloaddition in Water Using a Heterogeneous Cu-Catalyst

Several triazoles have been synthesized. They were obtained by a Cu-catalyzed cycloaddition of azides and alkynes. The reaction takes place in aqueous media under microwave irradiation using a copper catalyst based on porous glass. The products have been characterized by infrared, gas chromatography–mass spectrometry, ¹H NMR, and ¹³C NMR in addition to melting = point determination. Furthermore the in situ building of some azides and alkynes and the influence of the used metal species was investigated.     

A Protein‐Based Encapsulation System with Calcium‐Controlled Cargo Loading and Detachment

Protein‐based encapsulation systems have a wide spectrum of applications in targeted delivery of cargo molecules and for chemical transformations in confined spaces. By engineering affinity between cargo and container proteins it has been possible to enable the efficient and specific encapsulation of target molecules. Missing in current approaches is the ability to turn off the interaction after encapsulation to enable the cargo to freely diffuse in the lumen of the container. Separation between cargo and container is desirable in drug delivery applications and in the use of capsids as catalytic nanoparticles. We describe an encapsulation system based on the hepatitis B virus capsid in which an engineered high‐affinity interaction between cargo and capsid proteins can be modulated by Ca²⁺. Cargo proteins are loaded into capsids in the presence of Ca²⁺, while ligand removal triggers unbinding inside the container. We observe that confinement leads to hindered rotation of cargo inside the capsid. Application of the designed container for catalysis was also demonstrated by encapsulation of an enzyme with β‐glucosidase activity.     

MaxSynBio: Avenues Towards Creating Cells from the Bottom Up

A large German research consortium mainly within the Max Planck Society (“MaxSynBio”) was formed to investigate living systems from a fundamental perspective. The research program of MaxSynBio relies solely on the bottom‐up approach to synthetic biology. MaxSynBio focuses on the detailed analysis and understanding of essential processes of life through modular reconstitution in minimal synthetic systems. The ultimate goal is to construct a basic living unit entirely from non‐living components. The fundamental insights gained from the activities in MaxSynBio could eventually be utilized for establishing a new generation of biotechnological processes, which would be based on synthetic cell constructs that replace the natural cells currently used in conventional biotechnology.     

Can the Shape of Nanoparticles Enable the Targeting to Cancer Cells over Healthy Cells?

Macropinocytosis is a consequence of oncogenic alterations of cancer cells while most healthy cells are non-macropinocytic. It is currently unclear whether macropinocytic cancer cells can be targeted rather than healthy cells, by adjusting the shape and size of nanoparticles. Herein, the endocytosis of two differently shaped nanoparticles; nanorods and nanospheres are compared in cancer and healthy cells. The cells are breast epithelial cancer cells (MCF7) and breast epithelial healthy cells (MCF10A) and pancreas cancer cells (PANC-1 cells) and non-tumourogenic patient-derived cancer-associated fibroblasts (CAFs). The endocytosis pathway is quantified by a combination of pair correlation microscopy and endocytosis inhibitors. MCF7 cells use clathrin-mediated endocytosis and macropinocytosis to take up the nanorods while MCF10A cells use predominantly clathrin-mediated endocytosis. Based on the comparison of endocytic behavior of cancer and healthy cells, MCF7 cells can be induced to take up more nanorods and suppress the metabolism and endocytosis of nanorods in MCF10A cells. The nanorods allow targeting to breast cancer MCF7 cells and pancreas cancer cells over the healthy cells. This study opens exciting possibilities for shape to target the cancer cells over healthy cells, by adjusting nanoparticle shape.     

Direct View on Non-Equilibrium Heterogeneous Dynamics in Glassy Nanorods

Amorphous solids are potential candidates for room temperature applications, such as structural materials, due to their outstanding mechanical properties. For the first time, the local atomic dynamics of amorphous metallic nanorods are spatially resolved at room temperature using electron microscopy. Methodologically, quasi-equilibrium conditions are verified by two-time correlation functions. FeNiP is chosen as a suitable model system since a bamboo structure forms upon electrodeposition into nanotubular confinement, consisting of thin Fe-rich and Ni-rich amorphous layers. Therefore, the present nano-glassy structure allows studying the glass dynamics of two glassy phases at once, at the same time avoiding any preparation-related structural artifacts of the intrinsically electron-transparent samples. By comparing the local atomic mobility with the local composition and the local structural information of the glassy phases, correlations between medium-range order and time scales of heterogeneous glassy dynamics are consistently obtained.