Oligocarbonate Molecular Transporters: Oligomerization-Based Syntheses and Cell-Penetrating Studies

A new family of guanidinium-rich molecular transporters featuring a novel oligocarbonate backbone with 1,7-side chain spacing is described. Conjugates can be rapidly assembled irrespective of length in a one-step oligomerization strategy that can proceed with concomitant introduction of probes (or by analogy drugs). The new transporters exhibit excellent cellular entry as determined by flow cytometry and fluorescence microscopy, and the functionality of their drug delivery capabilities was confirmed by the delivery of the bioluminescent small molecule probe luciferin and turnover by its intracellular target enzyme

Structural reorganization of cylindrical nanoparticles triggered by polylactide stereocomplexation

YesCo-crystallization of polymers with different configurations/tacticities provides access to materials with enhanced performance. The stereocomplexation of isotactic poly(L-lactide) and poly(D-lactide) has led to improved properties compared with each homochiral material. Herein, we report the preparation of stereocomplex micelles from a mixture of poly(L-lactide)-b-poly(acrylic acid) and poly(D-lactide)-b-poly(acrylic acid) diblock copolymers in water via crystallization-driven self-assembly. During the formation of these stereocomplex micelles, an unexpected morphological transition results in the formation of dense crystalline spherical micelles rather than cylinders. Furthermore, mixture of cylinders with opposite homochirality in either THF/H2O mixtures or in pure water at 65 °C leads to disassembly into stereocomplexed spherical micelles. Similarly, a transition is also observed in a related PEO-b-PLLA/PEO-b-PDLA system, demonstrating wider applicability. This new mechanism for morphological reorganization, through competitive crystallization and stereocomplexation and without the requirement for an external stimulus, allows for new opportunities in controlled release and delivery applications.University of Warwick, Swiss National Science Foundation and the EPSRC. The Royal Society - an Industry Fellowship to A.P.D. The Engineering and Physical Sciences Research Council (EP/G004897/1) - funding to support postdoctoral fellowships for A.P.B. as well as funding for J.S. and M.A.D. through the Warwick Centre for Analytical Science (EP/F034210/1). The Science City Research Alliance and the HEFCE Strategic Development Fund - funding support. Some items of equipment that were used in this research were funded by Birmingham Science City, with support from Advantage West Midlands and part-funded by the European Regional Development Fund

Bacteria clustering by polymers induces the expression of quorum sense controlled phenotypes

Bacteria deploy a range of chemistries to regulate their behaviour and respond to their environment. Quorum sensing is one mean by which bacteria use chemical reactions to modulate pre-infection behaviour such as surface attachment. Polymers that can interfere with bacterial adhesion or the chemical reactions used for quorum sensing are thus a potential means to control bacterial population responses. Here we report how polymeric "bacteria sequestrants", designed to bind to bacteria through electrostatic interactions and thus inhibit bacterial adhesion to surfaces, induce the expression of quorum sensing controlled phenotypes as a consequence of cell clustering. A combination of polymer and analytical chemistry, biological assays and computational modelling has been used to characterise the feedback between bacteria clustering and quorum sensing signaling. We have also derived design principles and chemical strategies for controlling bacterial behaviour at the population leve

Melt Derived Blocky Copolyesters: New Design Features for Polycondensation

Melt polycondensation was utilized to chain extend polytrimethylene terephthalate with 1,3-propanediol based fluorinated isophthalic oligomers, resulting in copolymers with retained microstructure. Our findings point toward the formation of a blocky type copolymer. In general, formation of block or segmented copolymers from melt derived polycondensation is a very challenging task due to the propensity for adverse randomization reactions. Supported by size exclusion chromatography, our copolymers are fully chain extended, with no presence of the initial components. Furthermore, thermal differential scanning calorimetry has confirmed that the melt characteristics of the starting components are retained. In addition, interaction polymer chromatography and sequence distribution analysis using ¹³C NMR supports a blocky backbone microstructure. Seemingly, intermolecular chain end condensation occurs, whereas transesterification is dormant. While these findings open up new doors for polymer/materials development, we are particularly interested in these structures as melt additives to address oil repellency of polyester blends. When used in blends these blocky additives show an improvement in oil repellency compared with random additives of identical molar composition, i.e., they are more fluorine efficient

A supramolecularly assisted transformation of block-copolymer micelles into nanotubes

Once around the block: Incorporation of a rigid hydrogen-bonding benzamide unit, placed at the interface between two polymer blocks, in poly(ethylene glycol) (PEG)-(thio)urea-poly(L-lactide) (PLLA) block copolymers transforms the morphology of the block copolymers, from spherical micelles, as formed by PEG-PLLA diblock copolymers, into nanotubes in solutio