The detection and inactivation of pathogenic strains of bacteria continues to be an important therapeutic goal. Hence, there is a need for materials that can bind selectively to specific microorganisms, for diagnostic or anti-infective applications, but which can be formed from simple and inexpensive building blocks. Here, we exploit bacterial redox systems to induce a copper-mediated radical polymerisation of synthetic monomers at cell surfaces, generating polymers in situ that bind strongly to the microorganisms which produced them. This 'bacteriainstructed synthesis' can be carried out with a variety of microbial strains, and we show that the polymers produced are self-selective binding agents for the 'instructing' cell types. We further expand on the bacterial redox chemistries to 'click' fluorescent reporters onto polymers directly at the surfaces of a range of clinical isolate strains, allowing rapid, facile and simultaneous binding and visualisation of pathogens.The recognition and inactivation of pathogenic microorganisms remains a scientific challenge and a practical problem of enormous significance. 1 Conventional antibiotics have been extremely successful in combating microbial infections, but the emergence of resistant Reprints and permissions information is available online at.Users may view, print, copy, and download text and data-mine the content in such documents, for the purposes of academic research, subject always to the full Conditions of use:http://www.nature.com/authors/ editorial_policies/license.html#terms * Correspondence and requests for materials should be addressed to C. A. : cameron.alexander@nottingham.ac.uk, Fax: +44 115 951 5102; Tel: +44 115 846 7678 . Author contributionsAll authors contributed to design of the experiments. E. P.M., C. A., G. M., and F. F-T designed the polymer syntheses, K. W., D. C. and D. B., designed the microbiology assays. E. P. M., C.S., and S.G.S. carried out the experiments; C. A., E. P.M., G. M., F. F-T and K. W. analysed the data and wrote the paper. Additional informationSupplementary information is available in the online version of the paper. Competing financial interestsThe authors declare no competing financial interests. Europe PMC Funders GroupAuthor Manuscript Nat Mater. Author manuscript; available in PMC 2015 January 08. Published in final edited form as:Nat Mater. 2014 July ; 13(7): 748-755. doi:10.1038/nmat3949. Europe PMC Funders Author ManuscriptsEurope PMC Funders Author Manuscripts strains of many pathogens is an increasing concern. New approaches to prevent bacterial infections are required that do not invoke the selection of resistant populations. 2 Non-lethal means for targeting bacteria include inactivating their invasive pathways, for example by disrupting cell-cell signalling mechanisms known as Quorum Sensing within microbial populations, [3][4][5] or, more simply, by sequestering bacteria away from an infective site. 6 The latter route is attractive also from a diagnostic perspective, 7 as the binding of a specific orga...

The purpose of this Expert Review is to discuss the impact of click chemistry in nanosized drug delivery systems. Since the introduction of the click concept by Sharpless and coworkers in 2001, numerous examples of click reactions have been reported for the preparation and functionalization of polymeric micelles and nanoparticles, liposomes and polymersomes, capsules, microspheres, metal and silica nanoparticles, carbon nanotubes and fullerenes, or bionanoparticles. Among these click processes, Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC) has attracted most attention based on its high orthogonality, reliability, and experimental simplicity for non-specialists. A renewed interest in the use of efficient classical transformations has been also observed (e.g., thiol-ene coupling, Michael addition, Diels-Alder). Special emphasis is also devoted to critically discuss the click concept, as well as practical aspects of application of CuAAC to ensure efficient and harmless bioconjugation.

Bacteria deploy a range of chemistries to regulate their behaviour and respond to their environment. Quorum sensing is one method 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 therefore a potential means to control bacterial population responses. Here, we report how polymeric 'bacteria sequestrants', designed to bind to bacteria through electrostatic interactions and therefore 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 characterize the feedback between bacteria clustering and quorum sensing signalling. We have also derived design principles and chemical strategies for controlling bacterial behaviour at the population level.

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Outer membrane vesicles are nano-sized microvesicles shed from the outer membrane of Gram-negative bacteria and play important roles in immune priming and disease pathogenesis. However, our current mechanistic understanding of vesicle-host cell interactions is limited by a lack of methods to study the rapid kinetics of vesicle entry and cargo delivery to host cells. Here, we describe a highly sensitive method to study the kinetics of vesicle entry into host cells in real-time using a genetically encoded, vesicle-targeted probe. We found that the route of vesicular uptake, and thus entry kinetics and efficiency, are shaped by bacterial cell wall composition. The presence of lipopolysaccharide O antigen enables vesicles to bypass clathrin-mediated endocytosis, which enhances both their entry rate and efficiency into host cells. Collectively, our findings highlight the composition of the bacterial cell wall as a major determinant of secretion-independent delivery of virulence factors during Gram-negative infections.

Elastin-based side-chain polymers (EBPs) were prepared by the polymerization of a methacrylate derivative of the pentapeptide valine-proline-glycine-valine-glycine (VPGVG) using reversible additionfragmentation chain transfer (RAFT) polymerization. The polymerizations proceeded in a controlled manner, yielding polymers with a narrow molecular weight distribution (polydispersity indices 1.03-1.23) and molecular weights in good agreement with those predicted from the initial monomer:initiator ratio for the conversion obtained. The dithioester end groups of the resulting polymers were removed by reaction with azo initiator-derived radicals. The lower critical solution temperature (LCST) behavior of the series of EBPs so obtained was investigated in solutions of varying pH (1.5-5.1) and polymer concentration (0.11-0.97 mg/mL) and for polymers of different degrees of polymerization (29-88 repeating units). These EBPs behaved similarly to linear polypeptides, known as elastin-like peptides (ELPs); the transition temperature decreased with increasing polymer concentration and molecular weight. Unlike ELPs, but in common with previously reported EBPs, a strong dependence of transition temperature on pH was observed due to the presence of the carboxylic acid from the C-terminal residue in the peptide side chains. Significant differences between the EBPs described here and those reported earlier were found, however, regarding the transition temperature at a given pH and its variation with molecular weight. These variations are attributed to differences in architecture between the polymers described here (higher molecular weight homopolymers) and those reported earlier (A-B-A triblock copolymers with short EBP A blocks and a PEG B block).