AbstractThe introduction of controlled self-assembly into living organisms opens up desired biomedical applications in wide areas including bioimaging/assays, drug delivery, and tissue engineering. Besides the enzyme-activated examples reported before, controlled self-assembly under integrated stimuli, especially in the form of sequential input, is unprecedented and ultimately challenging. This study reports a programmable self-assembling strategy in living cells under sequentially integrated control of both endogenous and exogenous stimuli. Fluorescent polymerized vesicles are constructed by using cholinesterase conversion followed by photopolymerization and thermochromism. Furthermore, as a proof-of-principle application, the cell apoptosis involved in the overexpression of cholinesterase in virtue of the generated fluorescence is monitored, showing potential in screening apoptosis-inducing drugs. The approach exhibits multiple advantages for bioimaging in living cells, including specificity to cholinesterase, red emission, wash free, high signal-to-noise ratio.

AbstractDie Phosphorylierung und Dephosphorylierung von Peptiden durch Kinasen und Phosphatasen ist ein allgegenwärtiger Mechanismus der Signaltransduktion in biologischen Systemen. Eine unnatürlich hohe oder niedrige Aktivität dieser Enzyme steht im Zusammenhang mit vielen Krankheiten. Hier führen wir amphiphile Calixarene als supramolekulare Schlüsselkomponenten für einen Membrantransport von Peptiden ein, der sich durch Phosphorylierung regulieren lässt. Mithilfe von farbstoffbeladenen Liposomen zeigen wir, dass diese Calixarene als Gegenionen für etablierte zellpenetrierende Peptide fungieren und deren Transport effizient aktivieren können. Die ermittelten EC50-Werte liegen im niedrigen nanomolaren Bereich. Die Calixarene aktivieren sogar den Membrantransport von kurzen Peptiden, die Substrate für Kinasen in Signaltransduktionskaskaden sind. Dadurch dass das phosphorylierte Produkt viel weniger effektiv transportiert wird, ermöglicht dies die Regulierung des Membrantransports durch Proteinkinase A (PKA) und Proteinkinase C (PKC). Daraus folgt auch eine markierungsfreie Methode, um die Aktivität dieser Enzyme mittels Fluoreszenz nachzuweisen.

AbstractPhosphorylation and dephosphorylation of peptides by kinases and phosphatases is essential for signal transduction in biological systems, and many diseases involve abnormal activities of these enzymes. Herein, we introduce amphiphilic calixarenes as key components for supramolecular, phosphorylation-responsive membrane transport systems. Dye-efflux experiments with liposomes demonstrated that calixarenes are highly active counterion activators for established cell-penetrating peptides, with EC50 values in the low nanomolar range. We have now found that they can even activate membrane transport of short peptide substrates for kinases involved in signal transduction, whereas the respective phosphorylated products are much less efficiently transported. This allows regulation of membrane transport activity by protein kinase A (PKA) and protein kinase C (PKC), as well as monitoring of their activity in a label-free kinase assay.

A microcalorimetric study on molecular recognition of p-sulfonatocalix[4]arene derivatives at self-assembled interface in comparison with in bulk water was performed, inspired by the dramatic change in physicochemical characteristics from bulk water to interface. A total of six cationic molecules were screened as model guests, including ammonium (NH4+), guanidinium (Gdm+), N,N′-dimethyl-1,4-diazabicyclo[2.2.2]octane (DMDABCO2+), tropylium (Tpm+), N-methyl pyridinium (N-mPY+) and methyl viologen (MV2+). The complexation with NH4+, Gdm+ and DMDABCO2+ is pronouncedly enhanced when the recognition process moved from bulk water to interface, whereas the complexation stabilities with Tpm+, N-mPY+ and MV2+ increase slightly or even decrease to some extent. A more interesting phenomenon arises from the NH4+/Gdm+ pair that the thermodynamic origin at interface differs definitely from each other although with similar association constants. The results were discussed in terms of differential driving forces, electrostatic, hydrogen bond as well as π-stacking interactions, originating from the unique physicochemical features of interfaces, mainly the polarity and dielectric constant.The molecular recognition of sulfonatocalixarene at self-assembled interface was investigated by means of microcalorimetry, which is definitely different from that in aqueous phase owing to the unique physicochemical characteristics of interfaces.Download high-res image (127KB)Download full-size image

The design and development of novel broad-spectrum tunable photoluminescent materials for security printing with encrypted information is highly desirable. We construct a supramolecular co-assembly platform of amphiphilic cyclodextrin and calixarene, promoting energy transfer among three chromophores that are loaded by non-covalent interactions. A large matrix of colors was realized by delicately tuning the molar ratios of chromophores, which occupies most of the area in the Commission Internationale de l'Eclairage (CIE) chromaticity diagram. The elaborate supramolecular “cocktail” hides a dual-encryption coding, which exhibits feasible application as fluorescent security inks that are difficult to counterfeit but easy to authenticate.

Dissipative self-assembly is a chemical process ubiquitous in and essential to living systems. Its dynamic nature makes it quite appealing to directly visualize and monitor in real-time, thus facilitating the understanding of this phenomenon. Herein, we have demonstrated for the first time a dissipative self-assembling system that in situ exhibits intrinsic fluorescence only in the assembly state by the employment of AIEgens, enabling its direct visualization and real-time monitoring using fluorescence microscopy and spectroscopy, respectively. Fluorescence assay, as a non-invasive and real-time monitoring technique with high sensitivity and resolution, represents a privileged way to disclose the kinetics of dissipative systems, which is on demand on account of their dynamic feature. Furthermore, transient Förster resonance energy transfer was validated as a proof-of-principle function and also to afford dual-channel monitoring.

A novel FRET platform was fabricated based on a macrocyclic amphiphile, reliant on the self-sorting complexation of a donor on the periphery of the assemblies and entrapment of an acceptor within the inner hydrophobic phase. By tuning subtly the donor/acceptor ratio, white light emission was successfully achieved with high quantum yield.

A dynamic vesicle was constructed by the complexation of (dodecyloxybenzyl)tripropargylammonium and p-sulfonatocalix[4]arene, then the dynamic vesicle was cross-linked by a “click” reaction. The cross-linked vesicle presents improved stability over the dynamic one. Meanwhile, it can be disrupted with specific chemical stimuli to give the controlled release.

A dynamic vesicle was constructed by the complexation of (dodecyloxybenzyl)tripropargylammonium and p-sulfonatocalix[4]arene, then the dynamic vesicle was cross-linked by a “click” reaction. The cross-linked vesicle presents improved stability over the dynamic one. Meanwhile, it can be disrupted with specific chemical stimuli to give the controlled release.

A novel FRET platform was fabricated based on a macrocyclic amphiphile, reliant on the self-sorting complexation of a donor on the periphery of the assemblies and entrapment of an acceptor within the inner hydrophobic phase. By tuning subtly the donor/acceptor ratio, white light emission was successfully achieved with high quantum yield.