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We present a microcontact printing (μCP) routine suitable to introduce defined (sub-) microscale patterns on surface substrates exhibiting a high capillary activity and receptive to a silane-based chemistry. This is achieved by transferring functional trivalent alkoxysilanes, such as (3-aminopropyl)-triethoxysilane (APTES) as a low-molecular weight ink via reversible covalent attachment to polymer brushes grafted from elastomeric polydimethylsiloxane (PDMS) stamps. The brushes consist of poly{N-[tris(hydroxymethyl)-methyl]acrylamide} (PTrisAAm) synthesized by reversible addition–fragmentation chain-transfer (RAFT)-polymerization and used for immobilization of the alkoxysilane-based ink by substituting the alkoxy moieties with polymer-bound hydroxyl groups. Upon physical contact of the silane-carrying polymers with surfaces, the conjugated silane transfers to the substrate, thus completely suppressing ink-flow and, in turn, maximizing printing accuracy even for otherwise not addressable substrate topographies. We provide a concisely conducted investigation on polymer brush formation using atomic force microscopy (AFM) and ellipsometry as well as ink immobilization utilizing two-dimensional proton nuclear Overhauser enhancement spectroscopy (1H–1H-NOESY-NMR). We analyze the μCP process by printing onto Si-wafers and show how even distinctively rough surfaces can be addressed, which otherwise represent particularly challenging substrates.

A highly porous cryogel is prepared and subsequently functionalized with an atom transfer radical polymerization (ATRP) initiator at the surface. Two new glycomonomers are introduced, which possess deprotected mannose as well as glucose moieties. These are copolymerized with N-isopropylacrylamide (NiPAm) from the cryogel surface, providing a highly hydrophilic porous material, which is characterized by SEM, FT-IR spectroscopy, and NMR spectroscopy. This functionalized support can be applied for affinity chromatography of whole cells owing to the high pore space and diameter. Such an application is exemplified by investigating the ability to capture Escherichia coli bacteria, revealing selective binding interactions of the bacteria with the mannose glycopolymer-functionalized cryogel surface. Thus, the presented glycopolymer-cryogel represents a promising material for affinity chromatography or enrichment of cells.

A synthetic cell mimic in the form of giant glycosylated polymersomes (GGPs) comprised of a novel amphiphilic diblock copolymer is reported. A synthetic approach involving a poly(dimethylsiloxane) (PDMS) macro-chain transfer agent (macroCTA) and postpolymerization modification was used to marry the hydrophobic and highly flexible properties of PDMS with the biological activity of glycopolymers. 2-Bromoethyl acrylate (BEA) was first polymerized using a PDMS macroCTA ( Mn,th ≈ 4900 g·mol-1, Đ = 1.1) to prepare well-defined PDMS- b-pBEA diblock copolymers ( Đ = 1.1) that were then substituted with 1-thio-β-d-glucose or 1-thio-β-d-galactose under facile conditions to yield PDMS- b-glycopolymers. Compositions possessing ≈25% of the glycopolymer block (by mass) were able to adopt a vesicular morphology in aqueous solution (≈210 nm in diameter), as indicated by TEM and light scattering techniques. The resulting carbohydrate-decorated polymersomes exhibited selective binding with the lectin concanavalin A (Con A), as demonstrated by turbidimetric experiments. Self-assembly of the same diblock copolymer compositions using an electroformation method yielded GGPs (ranging from 2-20 μm in diameter). Interaction of these cell-sized polymersomes with fimH positive E. coli was then studied via confocal microscopy. The glucose-decorated GGPs were found to cluster upon addition of the bacteria, while galactose-decorated GGPs could successfully interact with (and possibly immobilize) the bacteria without the onset of clustering. This demonstrates an opportunity to modulate the response of these synthetic cell mimics (protocells) toward biological entities through exploitation of selective ligand-receptor interactions, which may be readily tuned through a considered choice of carbohydrate functionality.

Cationic polymers have been widely employed as gene delivery vectors to help circumvent extracellular and intracellular delivery barriers. Among them, polyethylenimine (PEI) is the most commonly used despite its associated high cytotoxicity. PEI is typically obtained by uncontrolled ring opening polymerisation of aziridine, leading to either linear polymer architectures with only secondary amines, or branched architectures containing primary, secondary, and tertiary amines. In contrast, we describe the preparation of hyperbranched poly(ethylenimine-co-oxazoline) that contains only secondary amines, via a fast thiol–yne based one pot reaction. A small library of these compounds with varying PEI contents was then used to study the effect of polymer architecture on pDNA polyplex formation, cytotoxicity, and in vitro transfection studies with plasmid DNA. Hyperbranched poly(ethylenimine-co-oxazoline) was found to have reduced toxicity compared to the commercial standard 25 000 g mol−1 branched PEI (bPEI), with transfection efficiencies only slightly lower than its bPEI counterpart. Obtained results highlight the importance of the polymer architecture on the transfection efficiency of a gene delivery system, which was demonstrated by excluding other parameters such as molecular weight and charge density.

Cationic polymers play a crucial role within the field of gene delivery offering the possibility to circumvent (biological) barriers in an elegant way. However, polymers are accompanied either by a high cytotoxicity or low efficiency. In this study, a series of high molar mass poly(2-oxazoline)-based copolymers was synthesized introducing 2-ethyl-2-oxazoline, ethylene imine, and primary amine bearing monomer units representing a new generation of poly(ethylene imine) (PEI). The potential of these modified PEIs as non-viral gene delivery agents was assessed and compared to linear PEI by studying the cytotoxicity, the polyplex characteristics, the transfection efficiency, and the cellular uptake using plasmid DNA (pDNA) as well as small interfering RNA (siRNA). High transfection efficiencies, even in serum containing media, were achieved using pDNA without revealing any cytotoxic effects on the cell viability at concentrations up to 1 mg mL−1. The delivery potential for siRNA was further investigated showing the importance of polymer composition for different genetic materials. To elucidate the origins for this superior performance, super-resolution and electron microscopy of transfected cells were used, identifying the endosomal release of the polymers as well as a reduced protein interaction as the main difference to PEI-based transfection processes. In this respect, the investigated copolymers represent remarkable alternatives as non-viral gene delivery agents.

A benzoin-derived diol linker was synthesized and used to generate biocompatible polyesters that can be fully decomposed on demand upon UV irradiation. Extensive structural optimization of the linker unit was performed to enable the defined encapsulation of diverse organic compounds in the polymeric structures and allow for a well-controllable polymer cleavage process. Selective tracking of the release kinetics of encapsulated model compounds from the polymeric nano- and microparticle containers was performed by confocal laser scanning microscopy in a proof-of-principle study. The physicochemical properties of the incorporated and released model compounds ranged from fully hydrophilic to fully hydrophobic. The demonstrated biocompatibility of the utilized polyesters and degradation products enables their use in advanced applications, for example, for the smart packaging of UV-sensitive pharmaceuticals, nutritional components, or even in the area of spatially selective self-healing processes.

Antimicrobial resistance is an increasingly serious challenge for public health and could result in dramatic negative consequences for the health care sector during the next decades. To solve this problem, antibacterial materials that are unsusceptible toward the development of bacterial resistance are a promising branch of research. In this work, a new type of polymeric antimicrobial peptide mimic featuring a bottlebrush architecture is developed, using a combination of reversible addition-fragmentation chain transfer (RAFT) polymerization and ring-opening metathesis polymerization (ROMP). This approach enables multivalent presentation of antimicrobial subunits resulting in improved bioactivity and an increased hemocompatibility, boosting the selectivity of these materials for bacterial cells. Direct probing of membrane integrity of treated bacteria revealed highly potent membrane disruption caused by bottlebrush copolymers. Multivalent bottlebrush copolymers clearly outperformed their linear equivalents regarding bioactivity and selectivity. The effect of segmentation of cationic and hydrophobic subunits within bottle brushes was probed using heterograft copolymers. These materials were found to self-assemble under physiological conditions, which reduced their antibacterial activity, highlighting the importance of precise structural control for such applications. To the best of our knowledge, this is the first example to demonstrate the positive impact of multivalence, generated by a bottlebrush topology in polymeric antimicrobial peptide mimics, making these polymers a highly promising material platform for the design of new bactericidal systems.

Intracellular persistence of bacteria represents a clinical challenge as bacteria can thrive in an environment protected from antibiotics and immune responses. Novel targeting strategies are critical in tackling antibiotic resistant infections. Synthetic antimicrobial peptides (SAMPs) are interesting candidates as they exhibit a very high antimicrobial activity. We first compared the activity of a library of ammonium and guanidinium polymers with different sequences (statistical, tetrablock and diblock) synthesized by RAFT polymerization against methicillin-resistant S. aureus (MRSA) and methicillin-sensitive strains (MSSA). As the guanidinium SAMPs were the most potent, they were used to treat intracellular S. aureus in keratinocytes. The diblock structure was the most active, reducing the amount of intracellular MSSA and MRSA by two-fold. We present here a potential treatment for intracellular, multi-drug resistant bacteria, using a simple and scalable strategy.

Controlling the size and charge of nanometer-sized objects is of upmost importance for their interactions with cells. We herein present the synthesis of poly(2-oxazoline) based nanogels comprising a hydrophilic shell and an amine containing core compartment. Amine groups were cross-linked using glutaraldehyde resulting in imine based nanogels. As a drug model, amino fluorescein was covalently immobilized within the core, quenching excessive aldehyde functions. By varying the amount of cross-linker, the zeta potential and, hence, the cellular uptake could be adjusted. The fluorescence of the nanogels was found to be dependent on the cross-linking density. Finally, the hemocompatibility of the described systems was studied by hemolysis and erythrocyte aggregation assays. While cellular uptake was shown to be dependent on the zeta potential of the nanogel, no harmful effects to red blood cells was observed, rendering the present system as an interesting toolbox for the production of nanomaterials with a defined biological interaction profile.

Polymer conjugated biologics form a multibillion dollar market, dominated by poly(ethylene glycol) (PEG). Recent reports linked PEGs to immunological concerns, fueling the need for alternative polymers. Therefore, we are presenting a strategy replacing PEG by poly(2-oxazoline) (POx) polymers using genetically engineered interleukin-4 (IL-4) featuring an unnatural amino acid for site-specific conjugation through bioorthogonal copper-catalyzed azide alkyne cycloaddition (CuAAC). Conjugation yields of IL-4-PEG were poor and did not respond to an increase in the copper catalyst. In contrast, POxylated IL-4 conjugates resulted in homogeneous conjugate outcome, as demonstrated electrophoretically by size exclusion chromatography and analytical ultracentrifugation. Furthermore, POxylation did not impair thermal and chemical stability, and preserved wild-type IL-4 activity for the conjugates as demonstrated by TF-1 cell proliferation and STAT-6 phosphorylation in HEK293T cells, respectively. In conclusion, POxylation provides an interesting alternative to PEGylation with superior outcome for the synthesis yield by CuAAC and resulting in conjugates with excellent thermal and chemical stress profiles as well as biological performances.

The combination of the reversible addition fragmentation chain transfer (RAFT) polymerization R-group grafting from approach and RAFT one-pot acrylamide multiblock methodology is used to synthesise complex bottle-brush architectures. This is demonstrated for block copolymer grafted side chains and the insertion of ungrafted blocks into the backbone to yield multi-segmented bottle-brushes.

Well defined ‘hyperstar’ copolymers were synthesized by combining hyperbranched polymers produced by thiol–yne chemistry with poly(oxazoline)s. The hyperbranched core was prepared using an AB2 monomer and a trifunctional alkene, applying a monomer feeding approach. The degree of branching was high (0.9) while maintaining low dispersities (1.3). Poly(2-ethyl-2-oxazoline) (PEtOx) functionalized with a thiol end group was coupled to the surface of the hyperbranched structure accessing terminal alkyne units. PEtOx-SH was produced by the termination of the living polymerization with ethyl xanthate and subsequent conversion to thiol under alkaline conditions. The degree of polymerization was varied producing PEtOx with 23 or 42 repeating units, respectively with a dispersity of around 1.1. After conjugation of the polymer arms, hyperstar copolymers were characterized by SEC, NMR spectroscopy, light scattering, and AFM. The polymers were able to encapsulate the hydrophobic dye Nile red within the core of the structure with loading efficiencies between 0.3 and 0.9 wt%. Cytotoxicity of the hyperstars was assessed using A2780 human ovarian carcinoma cells resulting in IC50 values of around 0.7 mg ml−1. Successful internalization and colocalization with lysosomal compartments was observed by confocal microscopy studies.\ud \ud

A Multisite copolymer with functionalizable units inserted at precise locations was synthesised by one-pot Reversible Addition–Fragmentation Chain-Transfer (RAFT) polymerization and sequential Single Monomer Unit Insertion (SMUI) and Chain Extension (ChainExt) using Styrene (Sty) and Maleic Anhydride (MAnh) as comonomers. The multisite copolymer was based on a polystyrene (PSty) backbone (ca. 5700 g mol−1) with MAnh units inserted locally at four positions in the backbone. First, a well-defined macroCTA (1400 g mol−1 – Đ = 1.07) was synthesised by optimized RAFT polymerization (high conversion, high livingness and low dispersity) of styrene (DP = 10) using industrial grade butyl-2-methyl-2-[(dodecylsulfanylthiocarbonyl)sulfanyl] propionate as chain transfer agent (CTA-Ester – 80% pure). Subsequently, the polystyrene macroCTA was used for one-pot SMUI using a small excess of MAnh monomer (DPtarget = 1.5). The copolymer was chain extended by styrene leading to a polystyrene backbone with MAnh units (1.5 in average) located in the middle of the chain. By repeating SMUI and ChainExt, several units of MAnh were inserted locally along the polystyrene backbone (every 10 units on average) to give a functionalizable multisite copolymer (Đ = 1.35). Long alkyl chains (stearyl) were added by esterification of maleic anhydride moieties to obtain branched architecture.

A looped flow process was designed for the synthesis of well-defined multiblock copolymers using reversible addition–fragmentation chain transfer (RAFT) polymerization. The reaction conditions were optimized to reach high conversions whilst maintaining a high end-group fidelity. The loop set-up proved to be a flexible, robust and time-efficient process for scaling-up multiblock copolymers.

Living systems are driven by molecular machines that are composed of folded polypeptide chains, which are assembled together to form multimeric complexes. Although replicating this type of system is a longstanding goal in polymer science, the complexity the structures impose is synthetically very challenging, and generating synthetic polymers to mimic the process of these assemblies appears to be a more appealing approach. To this end, we report a linear polymer programmable for stepwise folding and assembly to higher order structures. To achieve this, a diblock copolymer composed of 4-acryloylmorpholine and glycerol acrylate was synthesised with high precision via reversible addition fragmentation chain transfer polymerisation (Đ < 1.22). Both intramolecular folding and intermolecular assembly were driven by a pH responsive cross-linker, benzene-1,4-diboronic acid. The resulting intramolecular folded single chain nanoparticles were well defined (Đ < 1.16) and successfully assembled into a multimeric structure (Dh = 245 nm) at neutral pH with no chain entanglement. The assembled multimer was observed with a spherical morphology as confirmed by TEM and AFM. These structures were capable of unfolding and disassembling either at low pH or in the presence of sugar. This work offers a new perspective for the generation of adaptive smart materials.

Current approaches to generate core–shell nanoparticles for biomedical applications are limited by factors such as synthetic scalability and circulatory desorption of cytotoxic surfactants. Developments in controlled radical polymerization, particularly in dispersed states, represent a promising method of overcoming these challenges. In this work, well‐defined PEGylated nanoparticles are synthesized using reversible addition fragmentation chain transfer emulsion polymerization to control particle size and surface composition and were further characterized with light scattering, electron microscopy, and size exclusion chromatography. Importantly, the nanoparticles are found to be tolerated both in vitro and in vivo, without the need for any purification after particle synthesis. Pharmacokinetic and biodistribution studies in mice, following intraperitoneal injection of the nanoparticles, reveal a long (>76 h) circulation time and accumulation in the liver.

The controlled release of nucleic acids from cationic polymers is an important criteria for the design of gene delivery systems, and can be difficult to achieve due to the persistent positive charges required to initially complex the nucleic acids. Here, we report the use of highly branched tertiary amine-rich polymers for the complexation and release of dsRNA over a prolonged period of time. Controlled release of dsRNA is obtained via self-catalysed hydrolysis of the polymer side chains and associated change in electrostatic charge. Reversible addition–fragmentation chain transfer (RAFT) polymerization was utilised to synthesise a series of branched polymers of 2-(dimethylamino)ethyl acrylate (DMAEA), 3-(dimethylamino)propyl acrylate (DMAPA), and 2-(dimethylamino)ethyl methacrylate (DMAEMA) (MW ∼60 000–200 000 g mol−1) and copolymers thereof. The hydrolysis kinetics of all synthesised polymer materials were followed by 1H NMR spectroscopy. Complexation with dsRNA resulted in the formation of polyplex nanoparticles (N/P ratio of 5) with sizes of approximately 400 nm and surface charges of +15 mV. An agarose gel retardation assay showed sustained release of dsRNA from p(DMAEA-co-DMAEMA) for a period of more than 2 weeks. Unlike branched PEI commonly used for gene delivery, the majority of these systems showed little toxicity to cells (NIH3T3 fibroblasts). The results point towards pDMAPA and p(DMAEA-co-DMAEMA) being promising polymers for the controlled release of nucleic acids over prolonged periods.

Poly(urea)s are a polymer class widely used in industry. Their utilization in biomedical applications is already described, however, the use of controlled polymerization methods instead of polycondensation approaches would allow a better control over the degree of polymerization and the dispersity of the resulting polymers, improving their suitability for this particular field of application. Cationic ring-opening polymerization (CROP) as a chain growth polymerization enables those requirements and, additionally, allows the copolymerization with 2-oxazolines, which are generally known for their biocompatibility. In this report, a Boc protected oxazolidine imine monomer is synthesized and polymerized in a homopolymerization, as well as in a copolymerization with 2-ethyl-2-oxazoline (EtOx) via CROP. The synthesized polymers were analyzed regarding their chemical and physical properties, using NMR, GC, MALDI-MS, SEC, TGA and DSC. Copolymerization kinetics revealed the formation of quasi-block copolymers, able to self-assemble in aqueous solution as indicated by DLS.

Commercially-available linear and branched PEIs (LPEI and BPEI) were chemically-modified with carbohydrates and carbohydrate-mimetics to improve biocompatibility. Hydroxyl moieties were installed in a close proximity via reaction of PEI's amines with paraformaldehyde (pF) or glycidol. Mixing PEI with pF led to the formation of hemiaminal moieties as well as N-methylation of the backbone through an Eschweiler–Clarke-type rearrangement. The amount of attached hydroxyl groups depended on the initial amount of pF and the results were in agreement with NMR studies on model reactions with primary and secondary amines. The primary amines of BPEI triggered the ring-opening of glycidol and sugar-containing epoxides, in methanol and at room temperature. PEI chains modified with pF displayed the same cytotoxicity as the parent polymer, unless a sufficient amount of pF was added to trigger N-methylation of the backbone. In contrast, glycidol and sugar-functionalized BPEIs exhibited lower toxicity but similar (if not higher) transfection efficiency as compared to unmodified BPEI.

Self-assembling cyclic peptides (CP) consisting of amino acids with alternating D- and L-chirality form nanotubes by hydrogen bonding, hydrophobic interactions, and π–π stacking in solution. These highly dynamic materials are emerging as promising supramolecular systems for a wide range of biomedical applications. Herein, we discuss how varying the polymer conformation (linear vs. brush), as well as the number of polymer arms per peptide unimer affects the self-assembly of PEGylated cyclic peptides in different solvents, using small angle neutron scattering. Using the derived information, strong correlations were drawn between the size of the aggregates, solvent polarity, and its ability to compete for hydrogen bonding interactions between the peptide unimers. Using these data, it could be possible to engineer cyclic peptide nanotubes of a controlled length.

The synthesis of a new nanogel drug carrier system loaded with the anti-cancer drug doxorubicin (DOX) is presented. Poly(2-oxazoline) (POx) based nanogels from block copolymer micelles were cross-linked and covalently loaded with DOX using pH-sensitive Schiff' base chemistry. DOX loaded POx based nanogels showed a toxicity profile comparable to the free drug, while unloaded drug carriers showed no toxicity. Hemolytic activity and erythrocyte aggregation of the drug delivery system was found to be low and cellular uptake was investigated by flow cytometry and fluorescence microscopy. While the amount of internalized drug was enhanced when incorporated into a nanogel, the release of the drug into the nucleus was delayed. For in vivo investigations the nanogel drug delivery system was combined with a metronomic treatment of DOX. Low doses of free DOX were compared to equivalent DOX loaded nanogels in a xenograft mouse model. Treatment with POx based nanogels revealed a significant tumor growth inhibition and increase in survival time, while pure DOX alone had no effect on tumor progression. The biodistribution was investigated by microscopy of organs of mice and revealed a predominant localization of DOX within tumorous tissue. Thus, the POx based nanogel system revealed a therapeutic efficiency despite the low DOX concentrations and could be a promising strategy to control tumor growth with fewer side effects.

Multiblock copolymers (MBCPs) are an emerging class of materials that are becoming more accessible in recent years. However, to date there is still a lack of fundamental understanding of their physical properties. In particular, the glass transition temperature (Tg) which is known to be affected by the phase separation has not been well characterized experimentally. To this end, we report the first experimental study on the evolution of the Tgs and the corresponding phase separation of linear MBCPs with increasing number of blocks while keeping the overall degree of polymerization (DP) constant (DP = 200). Ethylene glycol methyl ether acrylate (EGMEA) and tert-butyl acrylate (tBA) were chosen as monomers for reversible addition-fragmentation chain transfer polymerization to synthesize MBCPs. We found the Tgs (as measured by differential scanning calorimetry) of EGMEA and tBA segments within the MCBPs to converge with increasing number of blocks and decreasing block length, correlating with the loss of the heterogeneity as observed from small-angle X-ray scattering (SAXS) analysis. The Tgs of the multiblock copolymers were also compared to the Tgs of the polymer blends of the corresponding homopolymers, and we found that Tgs of the polymer blends were similar to those of the respective homopolymers, as expected. SAXS experiments further demonstrated microphase separation of multiblock copolymers. This work demonstrates the enormous potential of multiblock architectures to tune the physical properties of synthetic polymers, by changing their glass transition temperature and their morphologies obtained from microphase separation, with domain sizes reaching under 10 nm.

Peptides and proteins control and direct all aspects of cellular function and communication. Having been honed by nature for millions of years, they also typically display an unsurpassed specificity for their biological targets. This underlies the continued focus on peptides as promising drug candidates. However, the development of peptides into viable drugs is hampered by their lack of chemical and pharmacokinetic stability and the cost of large scale production. One method to overcome such hindrances is to develop polymer systems that are able to retain the important structural features of these biologically active peptides, while being cheaper and easier to produce and manipulate chemically.\ud \ud This review illustrates these principles using examples of polymers designed to mimic antimicrobial host-defence peptides. The host-defence peptides have been identified as some of the most important leads for the next generation of antibiotics as they typically exhibit broad spectrum antimicrobial ability, low toxicity toward human cells and little susceptibility to currently known mechanisms of bacterial resistance. Their movement from the bench to clinic is yet to be realised, however, due to the limitations of these peptides as drugs. The literature provides a number of examples of polymers that have been able to mimic these peptides through all levels of structure, starting from specific amino acid sidechains, through to more global features such as overall charge, molecular weight and three-dimensional structure (e.g. α-helical). The resulting optimised polymers are able retain the activity profile of the peptides, but within a synthetic macromolecular construct that may be better suited to the development of a new generation of antimicrobial therapeutics. Such work has not only produced important new leads to combat the growing threat of antibiotic resistance, but may also open up new ways for polymers to mimic other important classes of biologically active peptides.\ud \ud

A photochemical strategy for the sequential dual compaction of single polymer chains is introduced. Two photoreactive methacrylates, with side chains bearing either a phenacyl sulfide (PS) or an alpha-methylbenzaldehyde (photoenol, PE) moiety, are selectively incorporated by one-pot iterative reversible-addition fragmentation chain transfer copolymerization into the outer blocks of a well-defined poly (methyl methacrylate) based ABC triblock copolymer possessing a nonfunctional spacer block (M-n = 23 400 g mol(-1), D = 1.2; approximate to 15 units of each photoreactive moieties of each type) as well as in model statistical copolymers bearing only one type of photoreactive unit. Upon UVA irradiation, PS and PE lead to highly reactive thioaldehydes and o-quinodimethanes, which rapidly react with dithiol and diacrylate linkers, respectively. The monomerfunctional copolymers are employed to establish the conditions for controlled intramolecular photo-crosslinking, which are subsequently applied to the bifunctional triblock copolymer. All compaction/folding experiments are monitored by size-exclusion chromatography and dynamic light scattering. The dual compaction consists of two events of dissimilar amplitude: the first folding step reveals a large reduction in hydrodynamic diameters, while the second compaction lead to a far less pronounced reduction of the single-chain nanoparticles size, consistent with the reduced degrees of freedom available after the first covalent compaction step.

The specific activity of proteins can be traced back to their highly defined tertiary structure, which is a result of a perfectly controlled intrachain folding process. In the herein presented work the folding of different distinct domains within a single macromolecule is demonstrated. RAFT polymerization was used to produce multiblock copolymers, which are decorated with pendant hydroxyl groups in foldable sections, separated by nonfunctional spacer blocks in between. OH-bearing blocks were folded using an isocyanate cross-linker prior to chain extension to form single chain nanoparticles (SCNP). After addition of a spacer block and a further OH decorated block, folding was repeated to generate individual SCNP within a polymer chain. Control experiments were performed indicating the absence of interblock cross-linking. SCNP were found to be condensed by a combination of covalent and supramolecular (hydrogen bonds) linkage. The approach was used to create a highly complex pentablock copolymer having three individually folded subdomains with an overall dispersity of 1.21. The successful formation of SCNP was confirmed by size exclusion chromatography (SEC), nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC), and atomic force microscopy (AFM).\ud \ud

Cellulose derivatives bearing azide- and alkyne moieties were prepared by conversion of cellulose p -toluenesulphonic acid ester with sodium azide, on one hand, and propargylamine, on the other. The products obtained were carboxymethylated to yield water soluble multifunctional cellulose derivatives. Elemental analysis, FTIR- and NMR spectroscopy were applied to prove the structure of the polymers. SEC of the hydrogel components revealed values of the degree of polymerization (DP) between 43 and 200 that are acceptable values after this multi-step reaction starting from celluloses with DP 600. The copper(I)-catalyzed 1,3-dipolar cycloaddition reaction (Huisgen-reaction) was applied for the cross-linking. Gel formation occurred within 55 and 1600 s after mixing of the aqueous solutions of both components and copper(I) catalyst. The gelation time was found to depend on both the degree of functionalization and the amount of copper(I) catalyst. FTIR spectroscopy revealed incomplete conversion of the reactive sites. The gels contain up to 98.4% water. Freeze-drying led to spongy materials with a porous structure as visualised by SEM.

The authors report the preparation of a novel range of functional polyacrylamide stabilized polystyrene nanoparticles, obtained by surfactant-free reversible addition-fragmentation chain transfer (RAFT) emulsion polymerization, their fluorescent tagging, cellular uptake, and biodistribution. The authors show the versatility of the RAFT emulsion process for the design of functional nanoparticles of well-defined size that can be used as drug delivery vectors. Functionalization with a fluorescent tag offers a useful visualization tool for tracing, localization, and clearance studies of these carriers in biological models. The studies are carried out by labeling the sterically stabilized latex particles chemically with rhodamine B. The fluorescent particles are incubated in a healthy human renal proximal tubular cell line model, and intravenously injected into a mouse model. Cellular localization and biodistribution of these particles on the biological models are explored.

Self-assembling peptides have the ability to spontaneously aggregate into large ordered structures. The reversibility of the peptide hydrogen bonded supramolecular assembly make them tunable to a host of different applications, although it leaves them highly dynamic and prone to disassembly at the low concentration needed for biological applications. Here we demonstrate that a secondary hydrophobic interaction, near the peptide core, can stabilise the highly dynamic peptide bonds, without losing the vital solubility of the systems in aqueous conditions. This hierarchical self-assembly process can be used to stabilise a range of different β-sheet hydrogen bonded architectures., Reversibility of peptide hydrogen bonded supramolecular assemblies makes them tunable but highly dynamic and prone to disassembly at the low concentration. Here the authors show a secondary hydrophobic interaction, near the peptide core that stabilises the peptide bonds, without losing the solubility of the systems in aqueous conditions.