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The clinical use of protein and peptide biotherapeutics requires fabrication of stable products. This particularly concerns stability towards aggregation of proteins or peptides. Here, we tested a hypothesis that interactions between a synthetic peptide, which is an aggregation-prone region analogue, and its homologous sequence on a protein of interest, could be exploited to design excipients which stabilise the protein against aggregation. A peptide containing the analogue of lysozyme aggregation-prone region (GILQINSRW) was conjugated to a RAFT agent and used to initiate the polymerisation of N-hydroxyethyl acrylamide, generating a GILQINSRW-HEA90 polymer, which profoundly reduced lysozyme aggregation. Substitution of tryptophan in GILQINSRW with glycine, to form GILQINSRG, revealed that tryptophan is a critical amino acid in the protein stabilisation by GILQINSRW-HEA90. Accordingly, polymeric peptide-mimetics of tryptophan, phenylalanine and isoleucine, which are often present in aggregation-prone regions, were synthesized. These were based on synthetic oligomers of acrylamide derivatives of indole-3 acetic acid (IND), phenylacetic acid (PHEN), or 2-methyl butyric acid (MBA), respectively, conjugated with hydrophilic poly(N-hydroxyethyl acrylamide) blocks to form amphiphilic copolymers denoted as INDm-, PHENm- and MTBm-b-HEAn. These materials were tested as protein stabilisers and it was shown that solution properties and the abilities of these materials to stabilise insulin and the peptide IDR 1018 towards aggregation are dependent on the chemical nature of their side groups. These data suggest a structure–activity relationship, whereby the indole-based INDm-b-HEAn peptide-mimetic displays properties of a potential stabilising excipient for protein formulations. [ABSTRACT FROM AUTHOR]

The temporary silencing of disease-associated genes utilising short interfering RNA (siRNA) is a potent and selective route for addressing a wide range of life limiting disorders. However, the few clinically approved siRNA therapies rely on lipid based formulations, which although potent, provide limited chemical space to tune the stability, efficacy and tissue selectivity. In this study, we investigated the role of molar mass and histidinylation for poly(lysine) based non-viral vectors, synthesised through a fully aqueous thermal condensation polymerisation. Formulation and in vitro studies revealed that higher molar mass derivatives yielded smaller polyplexes attributed to a greater affinity for siRNA at lower N/P ratios yielding greater transfection efficiency, albeit with some cytotoxicity. Histidinylation had a negligible effect on formulation size, yet imparted a moderate improvement in biocompatibility, but did not provide any meaningful improvement over silencing efficiency compared to non-histidinylated derivatives. This was attributed to a greater degree of cellular internalisation for non-histidinylated analogues, which was enhanced with the higher molar mass material. [ABSTRACT FROM AUTHOR]

Effective regenerative medicine requires delivery systems which can release multiple components at appropriate levels and at different phases of tissue growth and repair. However, there are few biomaterials and encapsulation techniques that are fully suitable for the loading and controlled release of multiple proteins. In this study we describe how proteins were physically and chemically loaded into a single coaxial electrospun fibre scaffold to obtain bi-phasic release profiles. Cyto-compatible polymers were used to construct the scaffold, using polyethylene oxide (PEO) for the core and polycaprolactone (PCL) reacted or mixed with (bis-aminopropyl)polyether (Jeffamine ED2003; JFA) for the shell. Horseradish peroxidase (HRP), a model protein, was loaded in the core and functionalised onto the scaffold surface by coupling of protein carboxyl groups to the available polymer amine groups. Fibre morphologies were evaluated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) and functional group content was determined using X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (TOF SIMS). Hydrophobicity profiles of the fibres before and after protein loading were evaluated by water contact angle (WCA) and the mechanical properties of the electrospun scaffolds were determined by performing tensile tests. The electrospun fibre scaffolds generated by reacting PEO/PCL with 1,6-diaminohexane and those from mixing PEO/PCL with JFA were further characterised for protein conjugation and release. Fibres prepared by the mixed PEO/PCL/JFA system were found to be the most appropriate for the simultaneous release of protein from the core and the immobilisation of another protein on the shell of the same scaffold. Moreover, JFA enhanced scaffold properties in terms of porosity and elasticity. Finally, we successfully demonstrated the cytocompatibility and cell response to protein-loaded and -conjugated scaffolds using HepG2 cells. Enhanced cell attachment (2.5 fold) was demonstrated using bovine serum albumin (BSA)-conjugated scaffolds, and increased metabolic activity observed with retinoic acid (RA)-loaded scaffolds (2.7 fold). [ABSTRACT FROM AUTHOR]

Dabrafenib is one of the most widely used of the new generation of targeted anti-cancer drugs. However, its therapeutic window varies for different patients and so there is an unmet need for methods to monitor the dose of drug which the patient receives and at the specific site where it acts. In the case of cancers, it is critical to measure the concentration of drug not just in the bloodstream overall, but in or near tumours, as these will not be the same over multiple time periods. A novel sensor based on an optical fibre long period grating (LPG) modified with a molecular imprinted polymer (MIP) has been developed with the ultimate aim of achieving minimally invasive measurements of Dabrafenib at the tumour site. A molecularly imprinted polymer specific for Dabrafenib was coated on a methacryloylalkoxysilane-functionalised optical fibre long period grating. In vitro experimental results demonstrate that the Dabrafenib sensitivity is 15.2 pm (μg mL−1)−1 (R2 = 0.993) with a limit of detection (LoD) of 74.4 μg mL−1 in serum solution. Moreover, the proposed sensor shows selective response to Dabrafenib over structurally similar 2-Aminoquinoline. [ABSTRACT FROM AUTHOR]

Gene therapies are undergoing a renaissance, primarily due to their potential for applications in vaccination for infectious diseases and cancers. Although the biology of these technologies is rapidly evolving, delivery strategies need to be improved to overcome the poor pharmacokinetics and cellular transport of nucleic acids whilst maintaining patient safety. In this work, we describe the divergent synthesis of biodegradable cationic dendrimers based on the amino acid ornithine as non-viral gene delivery vectors and evaluate their potential as delivery vectors for DNA and RNA. The dendrimers effectively complexed model nucleic acids at lower N/P ratios than polyethyleneimine and outperformed it in DNA transfection experiments with ratios above 5. Remarkably, all dendrimer polyplexes at N/P = 2 achieved up to 7-fold higher protein content over an optimized PEI formulation when used for transfections with self-amplifying RNA (saRNA). Finally, transfection studies utilizing human skin explants revealed an increase of cells producing protein from 2% with RNA alone to 12% with dendrimer polyplexes, attributed to expression enrichment predominantly in epithelial cells, fibroblasts and leukocytes, with minor enrichment in NK cells, T cells, monocytes, and B cells. Overall, this study indicates the clear potential of ornithine dendrimers as safe and effective delivery vectors for both DNA and RNA therapeutics. [ABSTRACT FROM AUTHOR]

A bis-epoxide monomer was synthesised in two steps from (R)-carvone, a terpenoid renewable feedstock derived from spearmint oil, and used to prepare β-aminoalcohol oligomers in polyaddition reactions with bis-amines without requiring solvent or catalyst. A sub-set of the resultant materials were readily water soluble and were investigated for antifungal activity in combination with the fungicide iodopropynyl-butylcarbamate (IPBC) or the antifungal drug amphotericin B. The oligo-(β-aminoalcohol)s alone were inactive against Trichoderma virens and Candida albicans but in combination with IPBC and amphotericin B demonstrated synergistic growth-inhibition of both fungi. Quantitative analysis showed that the presence of the terpene-based oligomers decreased the minimum inhibitory concentration (MIC) of IPBC by up to 64-fold and of amphotericin B by 8-fold. The efficacy of the combined formulation was further demonstrated with agar disk diffusion assays, which revealed that IPBC and amphotericin B reduced the growth of the fungi, as shown by zones of inhibition, to a greater extent when in the presence of the oligo-(β-aminoalcohol)s. These data suggest potential future use of these renewable feedstock derived oligomers in antifungal material and related biomedical applications. [ABSTRACT FROM AUTHOR]

The near-infrared absorbing conjugated polymer poly[2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4-b′]-dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)] (PCPDTBT) has been investigated as a contrast agent for optical and photoacoustic imaging. Lipophilic π-conjugated polymers can be efficiently encapsulated within self-assembling diblock copolymer poly(ethylene glycol) methyl ether-block-poly(lactide-co-glycolide) (PEG–PLGA) nanoparticles, although the effect of variations in PEG and PLGA chain lengths on nanoparticle properties, performance and biocompatibility have not yet been investigated. In this study, PEG–PLGA with different block lengths (PEG2kDa–PLGA4kDa, PEG2kDa–PLGA15kDa and PEG5kDa–PLGA55kDa) were used to encapsulate PCPDTBT. Nanoparticle sizes were smallest (<100 nm) when using PEG2kDa–PLGA4kDa, with <5% PCPDTBT content and a reduction in the total solids concentration of the organic phase. All PEG–PLGA nanoparticles were colloidally stable in water and serum-supplemented cell culture medium over 24 h at 37 °C, with slight evidence of protein surface adsorption. PEG2kDa–PLGA4kDa systems showed a threefold lower cytotoxicity (IC50 value) than the other two systems. Haemolytic activity was <2.5% for all systems and no platelet aggregation or inhibition of ADP-induced platelet aggregation was observed. Encapsulation of PCPDTBT within a PEG–PLGA matrix shifted fluorescence emission towards red wavelengths (760 nm in THF vs. 840 nm in nanoparticles) and reduced the quantum yield by 30–70-fold compared to THF. Nonetheless, PCPDTBT:PEG2kDa–PLGA4kDa systems had a marginally higher quantum yield and signal-to-background ratio in a phantom mouse compared with PEG2kDa–PLGA15kDa and PEG5kDa–PLGA55kDa systems. As a photoacoustic imaging probe, PCPDTBT:PEG2kDa–PLGA4kDa systems also showed a higher photoacoustic amplitude compared to higher molecular weight PEG–PLGA systems. Overall, the low molecular weight PEG2kDa–PLGA4kDa nanoparticle systems conferred the benefits of smaller sizes, reduced cytotoxicity and enhanced imaging performance compared to higher molecular weight matrix polymers. [ABSTRACT FROM AUTHOR]

Here we describe a rapid inkjet formulation method for screening newly-synthesised cationic materials for siRNA delivery into cancer cells. Reduction responsive oligo-β-aminoesters were prepared and evaluated for their ability to condense siRNA into polyplexes through a fast inkjet printing method. A direct relationship between the oligomer structures and charge densities, and the final cell response in terms of uptake rate and transfection efficacy, was found. The oligo-β-aminoesters were well-tolerated by the cancer cells, compared to conventional cationic polymers so far employed in gene delivery, and were as active in silencing of a representative luciferase gene. [ABSTRACT FROM AUTHOR]

We report the synthesis of thermo-responsive polymer brushes with Upper Critical Solution Temperature (UCST)-type behaviour on glass to provide a new means to control cell attachment. Thermoresponsive poly(N-acryloyl glycinamide)-stat-poly(N-phenylacrylamide) (PNAGAm–PNPhAm) brushes with three different monomer ratios were synthesized to give tunable phase transition temperatures (Tp) in solution. Surface energies of surface-grafted brushes of these polymers at 25, 32, 37 and 50 °C were calculated from contact angle measurements and atomic force microscopy (AFM) studies confirmed that these polymers were highly extended at temperatures close to Tp in physiologically-relevant media. Importantly, NIH-3T3 cells were attached on the collapsed PNAGAm–PNPhAm brush surface at 30 °C after 20 h incubation, while release of cells from the extended brushes was observed within 2 h after the culture temperature was switched to 37 °C. Furthermore, the changes in cell attachment followed changes in the Lewis base component of surface energy. The results indicate that, in contrast to the established paradigm of enhanced cell attachment to surfaces where polymers are above a Lower Critical Solution Temperature (LCST), these novel substrates enable detachment of cells from surfaces at temperatures above a UCST. In turn these responsive materials open new avenues for the use of polymer-modified surfaces to control cell attachment for applications in cell manufacture and regenerative medicine. [ABSTRACT FROM AUTHOR]

Here we describe a methoxy poly(ethyleneglycol)-b-poly(ε-decalactone) (mPEG-b-PεDL) copolymer and investigate the potential of the copolymer as a vehicle for solubilisation and sustained release of indomethacin (IND). The indomethacin loading and release from mPEG-b-PεDL micelles (amorphous cores) was compared against methoxy poly(ethyleneglycol)-b-poly(ε-caprolactone)(mPEG-b-PCL) micelles (semicrystalline cores). The drug–polymer compatibility was determined through a theoretical approach to predict drug incorporation into hydrated micelles. Polymer micelles were prepared by solvent evaporation and characterised for size, morphology, indomethacin loading and release. All the formulations generated spherical micelles but significantly larger mPEG-b-PεDL micelles were observed compared to mPEG-b-PCL micelles. A higher compatibility of the drug was predicted for PCL cores based on Flory–Huggins interaction parameters (χsp) using the Hansen solubility parameter (HSP) approach, but higher measured drug loadings were found in micelles with PεDL cores compared to PCL cores. This we attribute to the higher amorphous content in the PεDL-rich regions which generated higher micellar core volumes. Drug release studies showed that the semicrystalline PCL core was able to release IND over a longer period (80% drug release in 110 h) compared to PεDL core micelles (80% drug release in 72 h). [ABSTRACT FROM AUTHOR]

A family of novel ‘smart’ drug nanovectors based on 2-(methacryloyloxy)ethyl-3-chloro-4-hydroxybenzoate (MCH), a functional pH-responsive monomer, and poly(methoxy-ethylene glycol) methacrylate (PEGMA) block copolymers is presented. Modification of the monomers' relative ratios allowed facile switching from micellar (PEGMA11-b-MCH21) to polymersome-based (PEGMA11-b-MCH38) drug delivery nanocarriers. The ability of the latter to incorporate model anticancer drugs – tamoxifen, paclitaxel and doxorubicin hydrochloride – was investigated. High drug loading – up to 18 w/w% – was observed for tamoxifen, a hydrophobic drug which bears an amino group able to form ion pairs with MCH acidic functionalities. Non-loaded nanovectors were characterized (CAC, DLS and TEM), and were found to be very stable under physiological conditions (PBS pH 7.4, 37 °C), even in the presence of 10% plasma proteins for at least 48 h. Tamoxifen loaded nanocarriers showed slow drug release at pH 7.4 and faster release after exposure to weakly acidic environments, due to the loss of polymer/drug ionic interactions. Importantly, at pH 7.4 tamoxifen-loaded PEGMA11-b-MCH21 micelles were found to be less cytotoxic than free tamoxifen against MCF-7 cells, while under more acidic conditions, at pH 6.8, the opposite behaviour was observed, with a 10-fold increase in cytotoxicity for the micellar nanocarriers. The empty nanocarriers were found to be non-toxic in 48 h incubation time experiments. Pharmacokinetic studies proved the increased half-life and the slower clearance of tamoxifen after encapsulation in the micelles. These PEGMA-b-MCH based nanoassemblies could represent a novel promising delivery platform for low molecular weight ionisable drugs. [ABSTRACT FROM AUTHOR]

New classes of information-rich DNA block co-polymer conjugates were synthesised, encoded with thermoresponsive and biocompatible poly(tri(ethylene glycol)ethyl ether methacrylate) (pTriEGMA) chains and oligomeric nucleic acids connected by either bioreducible or non-reducible links. The pTriEGMA chains were grown from initiator-functionalised hybridised DNA, designed to assemble with toehold overhangs. Functional information in the conjugates was explored via dynamic light scattering (DLS) and atomic force microscopy (AFM), in order to evaluate (i) reversible self-assembly into supramolecular structures across the pTriEGMA phase transition temperature; (ii) conformational change via addition of competing DNA sequences across the toeholds, and (iii) reductive cleavage of polymer–DNA links. The results showed that discrete nanoscale conjugates could reversibly associate through pTriEGMA phase behaviour and that size and association behaviour in one class of conjugate could be switched by addition of a competing DNA sequence and by reduction to break the polymer–DNA links. Preliminary experiments with the DNA-conjugates as delivery systems for doxorubicin to a cancer cell line indicated good tolerability of the conjugates alone and cytotoxic efficacy when loaded with the drug. [ABSTRACT FROM AUTHOR]

Small interfering ribonucleic acids (siRNAs) form potentially the most important class of next generation therapeutics. However, achieving their efficient delivery in the correct dose, time and location in the body remains a significant challenge. Rapid developments in the chemistries of siRNA formulations are enabling new strategies to overcome the core obstacles to delivery which include poor ribonuclease (RNase) resistance, short biological half-life, lack of tissue targeting, inefficient cellular uptake and undesirable toxicity. In this review we describe these principal challenges and evaluate recent approaches proposed to overcome the chemical, biochemical and physiological barriers. The role of the specific chemical structure of siRNA is considered and an overview of selected literature-reported siRNA formulations is provided. These include chemically-modified siRNAs and analogues, aptamer–siRNA chimeras, self-assembled nanoparticles, lipid and polymer complexes, bioconjugates and fusion protein complexes. We conclude the review with an outlook for the clinical use of this highly promising, but pharmaceutically challenging biotherapeutic. [ABSTRACT FROM AUTHOR]

The article focuses on a research paper examining peptide-based amphiphiles and their ability to assemble into complex higher-order architectures by professor Sam Stupp. It is noted that water is one of the most important factors in driving the association of materials with connected hydrophilic and hydrophobic blocks. It is stated that the presence of bound water makes many protein interactions and a number of important protein DNA binding domains notable.

Cell based therapies offer potentially revolutionary treatments for a number of diseases, but are dependent on the culture and supply of defined cell types in appropriate numbers. In turn, this supply requires changes to current cell culture passaging methods, which commonly use enzymatic digestion. Here we demonstrate, for the first time, the use of thermoresponsive poly(methoxyethoxyethylmethacrylate-co-oligoethyleneglycolmethacrylate) (poly(MEO2MA-co-OEGMA)) as a responsive surface on which to culture embryonic stem cells (mouse; used as a model embryonic stem cell type). Thermo-responsive copolymer brushes composed of MEO2MA and OEGMA were grafted from hydroxyl plasma-polymer functionalised glass slides using atom transfer radical polymerisation (ATRP) and their thermo-responsive behaviour characterised. Feeder-free mouse embryonic stem cells (mESCs) were seeded on these surfaces following adsorption of fibronectin (to encourage cell attachment) and cultured for three days. Subsequent passaging experiments were performed over 10 passage cycles and the cells analysed for population doubling times and retention of the stem cell geno/phenotype. These thermoresponsive polymer/fibronectin surfaces were found to be suitable for mESC culture without promoting differentiation during the early stages of culture. This indicated that these materials have promise as a new generation of culture materials for enzyme free cell culture and passage suitable for generating cell populations for clinical applications. [ABSTRACT FROM AUTHOR]

The use of nucleic acids as therapeutics offers many potential benefits for treating disease. However, for these delicate yet potent biomolecules to be practical in the clinic, carrier vehicles are needed not only to protect the nucleic acids during transport in the body, but also release the biopolymers at the disease site. Polycations can meet the complex needs of nucleic acid delivery as they can condense the polyanionic nucleic acids to form stable polyelectrolyte complexes and, through appropriate design, can release the biotherapeutic at a target site. In this feature article, we review recent advances in the field, and indicate the ways in which future materials of this type might lead to enhanced therapies and treatments for currently untreatable diseases. [ABSTRACT FROM AUTHOR]