Selective Transport of Functional Polymer-Hybrid Vesicles into Cell Nuclei

The cell nucleus is the ultimate target for many therapeutic treatments including cancer, brain disorders and heart dysfunction. Therefore, organelle-specific nanocarriers (NCs) are highly sought after for delivering sufficient concentrations of the active therapeutic agent in situ. This requires the NCs to interact with the nucleocytoplasmic transport (NCT) to enter nuclear pore complexes (NPCs). Yet, little is known as to how NCs infiltrate this vital intracellular barrier to enter the nuclear interior. Furthermore, it is poorly understood how the physico-chemical NC properties influence this process. Here, ∼50 nm-sized synthetic NCs were developed based on polymer-hybrid vesicles, known as polymersomes. Following a bottom-up approach, biocompatible and amphiphilic PMOXA-PDMS-PMOXA triblock copolymers were self-assembled into NCs and surface-conjugated with nuclear localization sequences (NLS). Those NLS-NCs represent ideal candidates to study NCT, as they remain structurally intact during nuclear import due to the enhanced polymersome membrane stability and strength as compared to liposomes. Moreover, the NLS surface tags authenticate NCs as nucleus specific and enable the NCT mediated import. Applying a so-called film rehydration method permits encapsulating the hydrophilic model drug Ruthenium Red inside the aqueous vesicle cavity and post-treatment with Bodipy 630/650 allows intercalating a lipophilic model drug into the membrane of the same NC. The encapsulated drugs are consequently protected against premature degradation and carried together to the nucleus. In addition, NLS-NCs were used as large cargoes to study NCT mechanisms. Detailed chemical, biophysical and cellular analysis show that karyopherin receptors (Kaps) are required to bind and escort NLS-NCs through NPCs while Ran guanosine triphosphate (RanGTP) promotes their release from NPCs into the nuclear interior. Ultrastructural analysis by transmission electron microscopy further resolves NLS-NCs on transit in NPCs and inside the nucleus. By elucidating their ability to utilize NCT, these findings demonstrate the efficacy of polymersomes to deliver encapsulated payloads directly into cell nuclei

Organelle-specific targeting of polymersomes into the cell nucleus

Synthetic nanomaterials are being sought to shuttle therapeutic payloads directly into the cell nucleus as a major target for chemo- and gene-based therapies. However, it remains uncertain whether and how synthetic entities are able to bypass the nuclear pore complexes (NPCs) that regulate transport into and out of the nucleus. We have constructed biocompatible polymer vesicles that infiltrate NPCs and resolved their nuclear uptake mechanism in vitro and in vivo. Their ability to deliver payloads directly into cell nuclei is further validated by transmission electron microscopy.Organelle-specific nanocarriers (NCs) are highly sought after for delivering therapeutic agents into the cell nucleus. This necessitates nucleocytoplasmic transport (NCT) to bypass nuclear pore complexes (NPCs). However, little is known as to how comparably large NCs infiltrate this vital intracellular barrier to enter the nuclear interior. Here, we developed nuclear localization signal (NLS)-conjugated polymersome nanocarriers (NLS-NCs) and studied the NCT mechanism underlying their selective nuclear uptake. Detailed chemical, biophysical, and cellular analyses show that karyopherin receptors are required to authenticate, bind, and escort NLS-NCs through NPCs while Ran guanosine triphosphate (RanGTP) promotes their release from NPCs into the nuclear interior. Ultrastructural analysis by regressive staining transmission electron microscopy further resolves the NLS-NCs on transit in NPCs and inside the nucleus. By elucidating their ability to utilize NCT, these findings demonstrate the efficacy of polymersomes to deliver encapsulated payloads directly into cell nuclei

Dictator Games: A Meta Study

Over the last 25 years, more than a hundred dictator game experiments have been published. This meta study summarizes the evidence. Exploiting the fact that most experiments had to fix parameters they did not intend to test, the meta study explores a rich set of control variables for multivariate analysis. It shows that Tobit models (assuming that dictators would even want to take money) and hurdle models (assuming that the decision to give a positive amount is separate from the choice of amount, conditional on giving) outperform mere meta-regression and OLS

Nucleocytoplasmic Transport: A Paradigm for Molecular Logistics in Artificial Systems

Artificial organelles, molecular factories and nanoreactors are membrane-bound systems envisaged to exhibit cell-like functionality. These constitute liposomes, polymersomes or hybrid lipo-polymersomes that display different membrane-spanning channels and/or enclose molecular modules. To achieve more complex functionality, an artificial organelle should ideally sustain a continuous influx of essential macromolecular modules (i.e. cargoes) and metabolites against an outflow of reaction products. This would benefit from the incorporation of selective nanopores as well as specific trafficking factors that facilitate cargo selectivity, translocation efficiency, and directionality. Towards this goal, we describe how proteinaceous cargoes are transported between the nucleus and cytoplasm by nuclear pore complexes and the biological trafficking machinery in living cells (i.e. nucleocytoplasmic transport). On this basis, we discuss how biomimetic control may be implemented to selectively import, compartmentalize and accumulate diverse macromolecular modules against concentration gradients in artificial organelles

Chapter 6 Bio-inspired Polymer Membranes

Bio-inspired polymer membranes are artificial membranes designed to be combined with biomolecules (proteins, enzymes, mimics, nucleic acids), and provide both an increased mechanical stability of the overall system and an environment to preserve the functionality of the biomolecules. Here, we present synthetic membranes resulting from the self-assembly of amphiphilic block copolymers, both as 3D assemblies (polymer vesicles), and as 2D planar membranes (free standing films or membranes on solid/porous supports). Whilst in their early stage of research, the advantages of bio-inspired membranes support them as ideal candidates for the development of hybrid materials with multifunctionality and selectivity resulting from the presence of the biomolecules, and with stability and robustness due to the synthetic membrane. By serving as mimics of natural membranes with improved properties, bio-inspired synthetic membranes are on focus today for various applications in domains such as medicine, environment, and technology

Photodecarboxylative addition of carboxylates to phthalimides: a concise access to biologically active 3-(alkyl and aryl)methylene-1H-isoindolin-1-ones

A series of 3-(alkyl and aryl)methyleneisoindolin-1-one derivatives were synthesized in a simple two-step procedure using a recently established photodecarboxylative addition of carboxylates to phthalimides as the key-step. Subsequent acid-catalyzed dehydration and deprotection furnished the desired target compounds with high E-selectivity. The reaction sequence was applied to the synthesis of the known bioactive phenylethylene derivative, AKS-186. Different analogues, including heteroatom-containing isosteres were also synthesized using this approach

Synthesis and characterization of POSS-(PAA)8 star copolymers and GICs for dental applications

Objective To investigate the application of a new type of multiarm polymer resins in the formulation of Glass Ionic Cements. Methods A series of star copolymers of t-butyl acrylate has been prepared by ATRP using a multiarm POSS-Br initiator. The resulting POSS-co-t-butyl acrylate star copolymers with eight arms were subsequently hydrolysed by trifluoroacetic acid to produce the corresponding POSS-co-acrylic acid star copolymers. All of the copolymers have been characterized by H and C NMR and FTIR spectroscopies and TGA/DSC. The as-prepared star copolymers were mixed with the glass powder from Fuji IX GP to produce the GIC samples for compression testing. Results The new type of multiarm polymer resins have been shown to have narrow molecular weight distributions and thermal properties of the acrylic acid copolymers are similar to that of poly(acrylic acid), with a two stage degradation profile involving transitions at ≈140 °C and 250 °C, corresponding to anhydride formation and loss of carbon dioxide, respectively. In aqueous solution the POSS-co-acrylic acid copolymers form aggregates with ≈33 nm dimensions. When aqueous solutions of POSS-(PAA) are mixed with a glass powder, a rigid glass ionomer cement, GIC, is formed with a maximum compressive stress significantly greater than that for a linear PAA GIC of a comparable polymer molecular weight. Significance Therefore, these POSS-(PAA) copolymers demonstrate the potential for the application of well characterized star copolymers in the future development of new GICs as dental materials