Porous sulfur polymers for effective aqueous-phase organic contaminant removal

Sulfur polymers produced through 'inverse vulcanization' exhibit various attributes, such as photocatalytic activity and a high capacity to adsorb heavy metals. Nevertheless, there is a lack of research investigating the use of sulfur polymers as materials for the removal of organic contaminants. In this work, porous sulfur polymers (PSPs) were synthesized from elemental sulfur and 1,3-diisopropenylbenzene, with porosity introduced via salt templating. The result is a material that can strongly adsorb and chemically neutralize a model organic contaminant (caffeine). PSPs show adsorption up to 5 times higher than a leading adsorption material (activated carbon). Furthermore, either the adsorption or degradation processes can govern the removal efficiency depending on the synthesis parameters of PSPs. This is the first-ever report demonstrating sulfur polymers as effective materials for removing emerging contaminants from water. The versatile synthesis of sulfur polymers offers variation, which means that there is much more to explore in this exciting research area.

X-Ray Visible Protein Scaffolds by Bulk Iodination

Protein-based biomaterial use is expanding within medicine, together with the demand to visualize their placement and behavior in vivo. However, current medical imaging techniques struggle to differentiate between protein-based implants and surrounding tissue. Here a fast, simple, and translational solution for tracking transplanted protein-based scaffolds is presented using X-ray CT-facilitating long-term, non-invasive, and high-resolution imaging. X-ray visible scaffolds are engineered by selectively iodinating tyrosine residues under mild conditions using readily available reagents. To illustrate translatability, a clinically approved hernia repair mesh (based on decellularized porcine dermis) is labeled, preserving morphological and mechanical properties. In a mouse model of mesh implantation, implants retain marked X-ray contrast up to 3 months, together with an unchanged degradation rate and inflammatory response. The technique's compatibility is demonstrated with a range of therapeutically relevant protein formats including bovine, porcine, and jellyfish collagen, as well as silk sutures, enabling a wide range of surgical and regenerative medicine uses. This solution tackles the challenge of visualizing implanted protein-based biomaterials, which conventional imaging methods fail to differentiate from endogenous tissue. This will address previously unanswered questions regarding the accuracy of implantation, degradation rate, migration, and structural integrity, thereby accelerating optimization and safe translation of therapeutic biomaterials.

Sustained release ocular drug delivery systems for glaucoma therapy

INTRODUCTION

Glaucoma is a group of progressive optic neuropathies resulting in irreversible blindness. It is associated with an elevation of intraocular pressure (>21 mm Hg) and optic nerve damage. Reduction of the intraocular pressure (IOP) through the administration of ocular hypotensive eye drops is one of the most common therapeutic strategies. Patient adherence to conventional eye drops remains a major obstacle in preventing glaucoma progression. Additional problems emerge from inadequate patient education as well as local and systemic side effects associated with adminstering ocular hypotensive drugs.

AREAS COVERED

Sustained-release drug delivery systems for glaucoma treatment are classified into extraocular systems including wearable ocular surface devices or multi-use (immediate-release) eye formulations (such as aqueous solutions, gels; ocular inserts, contact lenses, periocular rings, or punctual plugs) and intraocular drug delivery systems (such as intraocular implants, and microspheres for supraciliary drug delivery).

EXPERT OPINION

Sustained release platforms for the delivery of ocular hypotensive drugs (small molecules and biologics) may improve patient adherence and prevent vision loss. Such innovations will only be widely adopted when efficacy and safety has been established through large-scale trials. Sustained release drug delivery can improve glaucoma treatment adherence and reverse/prevent vision deterioration. It is expected that these approaches will improve clinical management and prognosis of glaucoma.

Synthesis of aromatic 1,2-disulfonimides and their prospects as monomers

The correlation between chemical structure and selective transport properties in polyimides led to the suggestion of poly-1,2-disulfonimides as materials for high-performance diffusion membranes. Higher polarity along with steric features of...

pH-Responsive nanocomposite fibres allowing MRI monitoring of drug release

Magnetic resonance imaging (MRI) is one of the most widely-used non-invasive clinical imaging tools, producing detailed anatomical images whilst avoiding side effects such as trauma or X-ray radiation exposure. In this article, a new approach to non-invasive monitoring of drug release from a delivery vehicle via MRI was developed, using pH-responsive Eudragit L100 and S100 fibres encapsulating superparamagnetic iron oxide nanoparticles (SPIONs) and carmofur (a drug used in the treatment of colon cancer). Fibres were prepared by electrospinning, and found to be smooth and cylindrical with diameters of 645 ± 225 nm for L100 and 454 ± 133 nm for S100. The fibres exhibited pH responsive dissolution behaviour. Around the physiological pH range, clear pH-responsive proton relaxation rate changes due to matrix swelling/dissolution can be observed: r2 values of L100 fibres increase from 29.3 ± 8.3 to 69.8 ± 2.5 mM-1 s-1 over 3 h immersion in a pH 7.4 medium, and from 13.5 ± 2.0 mM-1 s-1 to 42.1 ± 3.0 mM-1 s-1 at pH 6.5. The r2 values of S100 fibres grow from 30.4 ± 4.4 to 64.7 ± 1.0 mM-1 s-1 at pH 7.4, but at pH 6.5, where the S100 fibres are not soluble, r2 remains very low (< 4 mM-1 s-1). These dramatic changes in relaxivity demonstrate that pH-responsive dissolution results in SPION release. In vitro drug release studies showed the formulations gave rapid release of carmofur at physiological pH values (pH 6.5 and 7.4), and acid stability studies revealed that they can protect the SPIONs from digestion in acid environments, giving the fibres potential for oral administration. Exploration of the relationship between relaxivity and carmofur release suggests a linear correlation (R2 > 0.94) between the two. Mathematical equations were developed to predict carmofur release in vitro, with very similar experimental and predicted release profiles obtained. Therefore, the formulations developed herein have the potential to be used for non-invasive monitoring of drug release in vivo, and could ultimately result in dramatic reductions to off-target side effects from interventions such as chemotherapy.

Ring-fused dimethoxybenzimidazole-benzimidazolequinone (DMBBQ): tunable halogenation and quinone formation using NaX/Oxone

Ring-fused benzimidazolequinones are well-known anti-tumour agents, but dimeric ring-fused adducts are new. The alicyclic [1,2-a] ring-fused dimethoxybenzimidazole-benzimidazolequinone (DMBBQ) intermediate allows late-stage functionalization of bis-p-benzimidazolequinones. DMBBQs are chlorinated and brominated at the p-dimethoxybenzene site using nontoxic sodium halide and Oxone in HFIP/water. X-ray crystallography is used to rationalize site preference in terms of the discontinuity in conjugation in the DMBBQ system. Quinone formation occurs by increasing in situ halogen generation and water. Conversely, radical trifluoromethylation occurs at the quinone of the DMBBQ.

Surface Interactions and Mechanisms Study on the Removal of Iodide from Water by Use of Natural Zeolite-Based Silver Nanocomposites

In this work a natural zeolite was modified with silver following two different methods to derive Ag2O and Ag0 nanocomposites. The materials were fully characterized and the results showed that both materials were decorated with nanoparticles of size of 5-25 nm. The natural and modified zeolites were used for the removal of iodide from aqueous solutions of initial concentration of 30-1400 ppm. Natural zeolite showed no affinity for iodide while silver forms were very efficient reaching a capacity of up to 132 mg/g. Post-adsorption characterizations showed that AgI was formed on the surface of the modified zeolites and the amount of iodide removed was higher than expected based on the silver content. A combination of experimental data and characterizations indicate that the excess iodide is most probably related to negatively charged AgI colloids and Ag-I complexes forming in the solution as well as on the surface of the modified zeolites.

Exploring precision polymers to fine-tune magnetic resonance imaging properties of iron oxide nanoparticles

The use of bio-polymers as stabilising agents for iron oxide-based negative magnetic resonance imaging (MRI) contrast agents has become popular in recent years, however the wide polydispersity of biologically-derived and commercially available polymers limits the ability to produce truly tuneable and reproducible behaviour, a major challenge in this area. In this work, stable colloids of iron oxide nanoparticles were prepared utilising precision-engineered bio-polymer mimics, poly(2-acrylamido-2-methylpropane sodium sulfonate) (P(AMPS)) polymers, with controlled narrow polydispersity molecular weights, as templating stabilisers. In addition to producing magnetic colloids with excellent MRI contrast capabilities (r₂ values reaching 434.2 mM^-1 s^-1 at 25 °C and 23 MHz, several times higher than similar commercial analogues), variable field relaxometry provided unexpected important insights into the dynamic environment of the hydrated materials, and hence their exceptional MRI behaviour. Thanks to the polymer's templating backbone and flexible conformation in aqueous suspension, nanocomposites appear to behave as "multi-core" clustered species, enhancing interparticle interactions whilst retaining water diffusion, boosting relaxation properties at low frequency. This clustering behaviour, evidenced by small-angle X-ray scattering, and strong relaxometric response, was fine-tuned using the well-defined molecular weight polymer species with precise iron to polymer ratios. By also showing negligible haemolytic activity, these nanocomposites exhibit considerable potential for MRI diagnostics.

Radio-metal cross-linking of alginate hydrogels for non-invasive in vivo imaging

Alginate hydrogels are cross-linked polymers with high water content, tuneable chemical and material properties, and a range of biomedical applications including drug delivery, tissue engineering, and cell therapy. However, their similarity to soft tissue often renders them undetectable within the body using conventional bio-medical imaging techniques. This leaves much unknown about their behaviour in vivo, posing a challenge to therapy development and validation. To address this, we report a novel, fast, and simple method of incorporating the nuclear imaging radio-metal 111In into the structure of alginate hydrogels by utilising its previously-undescribed capacity as an ionic cross-linking agent. This enabled non-invasive in vivo nuclear imaging of hydrogel delivery and retention across the whole body, over time, and across a range of model therapies including: nasal and oral drug delivery, stem cell transplantation, and cardiac tissue engineering. This information will facilitate the development of novel therapeutic hydrogel formulations, encompassing alginate, across disease categories.

In situ formation of low molecular weight organogelators for slick solidification

We have investigated the in situ formation of Low Molecular Weight Organogelator (LMWO) molecules in oil-on-water slicks through dual reactive precursor injection. This method alleviates the need for any carrier solvent or prior heating, therefore reducing the environmental impact of LMWOs, giving instantaneous gelation, even at low temperatures (−5 °C). We show minimal leaching from our gels into the water layer.

Instantaneous gelation: a reactive precursors approach for the near-instant gelation of oil-on-water slicks down to −5 °C.

Influence of Solvent in Crystal Engineering: A Significant Change to the Order-Disorder Transition in Ferrocene

We present the structure of a novel solvate adduct formed by dissolving ferrocene, FeCp₂, in hexafluorobenzene, C₆F₆. This adduct demonstrates the remarkably strong interactions between the five-membered aromatic rings of FeCp₂ and the six-membered aromatic ring of C₆F₆. These molecular interactions are sufficiently strong and anisotropic to change the temperature of the order-disorder transition of the ferrocene molecule from below ca. 164 K to RT. No solvate adduct could be formed between benzene and FeCp₂. These observations will be of particular relevance to the crystal engineering community, whose goal is the design of solids with bespoke properties.

Surface radio-mineralisation mediates chelate-free radiolabelling of iron oxide nanoparticles

We introduce the concept of surface radio-mineralisation (SRM) to describe the chelate-free radiolabelling of iron-oxide and ferrite nanoparticles. We demonstrate the effectiveness of SRM with both 111In and 89Zr for bare, polymer-matrix multicore, and surface-functionalised magnetite/maghemite nanoparticles; and for bare Y3Fe5O12 nanoparticles. By analogy with geological mineralisation (the hydrothermal deposition of metals as minerals in ore bodies or lodes) we demonstrate that the heat-induced and aqueous SRM process deposits radiometal-oxides onto the nanoparticle or core surfaces, passing through the matrix or coating if present, without changing the size, structure, or magnetic properties of the nanoparticle or core. We show in a mouse model followed over 7 days that the SRM is sufficient to allow quantitative, non-invasive, prolonged, whole-body localisation of injected nanoparticles with nuclear imaging.

A new family of urea-based low molecular-weight organogelators for environmental remediation: the influence of structure

Gelation processes grant access to a wealth of soft materials with tailorable properties, in applications as diverse as environmental remediation, biomedicine and electronics. Several classes of self-assembling gelators have been studied and employ non-covalent bonds to direct assembly, but recently attention has come to focus on how the overall shape of the gelator molecule impacts its gelation. Here we study a new sub-family of low molecular weight organogelators and explore how steric rearrangement influences their gelation. The gels produced are characterised with X-ray diffraction and small-angle neutron scattering (SANS) to probe their ex situ and in situ gelation mechanisms. The best examples were then tested for environmental remediation applications, gelling petrol and oils in the presence of water and salts.

Chemically Treated 3D Printed Polymer Scaffolds for Biomineral Formation

We present the synthesis of nylon-12 scaffolds by 3D printing and demonstrate their versatility as matrices for cell growth, differentiation, and biomineral formation. We demonstrate that the porous nature of the printed parts makes them ideal for the direct incorporation of preformed nanomaterials or material precursors, leading to nanocomposites with very different properties and environments for cell growth. Additives such as those derived from sources such as tetraethyl orthosilicate applied at a low temperature promote successful cell growth, due partly to the high surface area of the porous matrix. The incorporation of presynthesized iron oxide nanoparticles led to a material that showed rapid heating in response to an applied ac magnetic field, an excellent property for use in gene expression and, with further improvement, chemical-free sterilization. These methods also avoid changing polymer feedstocks and contaminating or even damaging commonly used selective laser sintering printers. The chemically treated 3D printed matrices presented herein have great potential for use in addressing current issues surrounding bone grafting, implants, and skeletal repair, and a wide variety of possible incorporated material combinations could impact many other areas.

Nanoscale, conformal films of graphitic carbon nitride deposited at room temperature: a method for construction of heterojunction devices

Graphitic carbon nitrides (GCNs) represent a family of 2D materials composed of carbon and nitrogen with variable amounts of hydrogen, used in a wide variety of applications. We report a method of room temperature thin film deposition which allows ordered GCN layers to be deposited on a very wide variety of substrates, including conductive glass, flexible plastics, nanoparticles and nano-structured surfaces, where they form a highly conformal coating on the nanoscale. Film thicknesses of below 20 nm are achievable. In this way we construct functional nanoscale heterojunctions between TiO₂ nanoparticles and GCN, capable of producing H₂ photocatalytically under visible light irradiation. The films are hydrogen rich, have a band gap around 1.7 eV, display transmission electron microscopy lattice fringes as well as X-ray diffraction peaks despite being deposited at room temperature, and show characteristic Raman and IR bands. We use cluster etching to reveal the chemical environments of C and N in GCN using X-ray photoelectron spectroscopy. We elucidate the mechanism of this deposition, which operates via sequential surface adsorption and reaction analogous to atomic layer deposition. The mechanism may have implications for current models of carbon nitride formation.

Understanding the Effect of Functional Groups on the Seeded Growth of Copper on Carbon Nanotubes for Optimizing Electrical Transmission

We present a study of the seeded growth of copper on the surface of two classes of single-walled carbon nanotubes (SWNTs) in order to compare the effects of surface functional groups. Pyridine-functionalized HiPco SWNTs and ultrashort SWNTs (US-SWNTs) were synthesized (py-SWNTs and py-US-SWNTs, respectively), and the functionality was used as seed sites for copper, via an aqueous electroless deposition reaction, as a comparison to the carboxylic acid functionality present on piranha-etched SWNTs and the native US-SWNTs. UV-vis spectroscopy demonstrated the take-up of Cu(II) ions by the functionalized SWNTs. TEM showed that the SWNTs with pyridine functionality more rapidly produced a more even distribution of copper seeds with a narrower size distribution (3-12 nm for py-US-SWNTs) than those SWNTs with oxygen functional groups (ca. 30 nm), showing the adventitious role of the pyridine functional group in the seeding process. Seed composition was confirmed as Cu(0) by XPS and SAED. Copper growth rate and morphology were shown to be affected by degree of pyridine functionality, the length of the SWNT, and the electroless reaction solvent used.

Active removal of waste dye pollutants using Ta3N5/W18O49 nanocomposite fibres

A scalable solvothermal technique is reported for the synthesis of a photocatalytic composite material consisting of orthorhombic Ta₃N₅ nanoparticles and WO_x≤3 nanowires. Through X-ray diffraction and X-ray photoelectron spectroscopy, the as-grown tungsten(VI) sub-oxide was identified as monoclinic W₁₈O₄₉. The composite material catalysed the degradation of Rhodamine B at over double the rate of the Ta₃N₅ nanoparticles alone under illumination by white light, and continued to exhibit superior catalytic properties following recycling of the catalysts. Moreover, strong molecular adsorption of the dye to the W₁₈O₄₉ component of the composite resulted in near-complete decolourisation of the solution prior to light exposure. The radical species involved within the photocatalytic mechanisms were also explored through use of scavenger reagents. Our research demonstrates the exciting potential of this novel photocatalyst for the degradation of organic contaminants, and to the authors' knowledge the material has not been investigated previously. In addition, the simplicity of the synthesis process indicates that the material is a viable candidate for the scale-up and removal of dye pollutants on a wider scale.

Enhancing the Antibacterial Activity of Light-Activated Surfaces Containing Crystal Violet and ZnO Nanoparticles: Investigation of Nanoparticle Size, Capping Ligand, and Dopants

Healthcare-associated infections pose a serious risk for patients, staff, and visitors and are a severe burden on the National Health Service, costing at least £1 billion annually. Antimicrobial surfaces significantly contribute toward reducing the incidence of infections as they prevent bacterial adhesion and cause bacterial cell death. Using a simple, easily upscalable swell-encapsulation-shrink method, novel antimicrobial surfaces have been developed by incorporating metal oxide nanoparticles (NPs) and crystal violet (CV) dye into medical-grade polyurethane sheets. This study compares the bactericidal effects of polyurethane incorporating ZnO, Mg-doped ZnO, and MgO. All metal oxide NPs are well defined, with average diameters ranging from 2 to 18 nm. These materials demonstrate potent bactericidal activity when tested against clinically relevant bacteria such as Escherichia coli and Staphylococcus aureus. Additionally, these composites are tested against an epidemic strain of methicillin-resistant Staphylococcus aureus (MRSA) that is rife in hospitals throughout the UK. Furthermore, we have tested these materials using a low light intensity (∼500 lx), similar to that present in many clinical environments. The highest activity is achieved from polymer composites incorporating CV and ∼3 nm ZnO NPs, and the different performances of the metal oxides have been discussed.

Magnetic hyperthermia controlled drug release in the GI tract: solving the problem of detection

Drug delivery to the gastrointestinal (GI) tract is highly challenging due to the harsh environments any drug- delivery vehicle must experience before it releases it's drug payload. Effective targeted drug delivery systems often rely on external stimuli to effect release, therefore knowing the exact location of the capsule and when to apply an external stimulus is paramount. We present a drug delivery system for the GI tract based on coating standard gelatin drug capsules with a model eicosane- superparamagnetic iron oxide nanoparticle composite coating, which is activated using magnetic hyperthermia as an on-demand release mechanism to heat and melt the coating. We also show that the capsules can be readily detected via rapid X-ray computed tomography (CT) and magnetic resonance imaging (MRI), vital for progressing such a system towards clinical applications. This also offers the opportunity to image the dispersion of the drug payload post release. These imaging techniques also influenced capsule content and design and the delivered dosage form. The ability to easily change design demonstrates the versatility of this system, a vital advantage for modern, patient-specific medicine.

Advanced Compositional Analysis of Nanoparticle-polymer Composites Using Direct Fluorescence Imaging

The fabrication of polymer-nanoparticle composites is extremely important in the development of many functional materials. Identifying the precise composition of these materials is essential, especially in the design of surface catalysts, where the surface concentration of the active component determines the activity of the material. Antimicrobial materials which utilize nanoparticles are a particular focus of this technology. Recently swell encapsulation has emerged as a technique for inserting antimicrobial nanoparticles into a host polymer matrix. Swell encapsulation provides the advantage of localizing the incorporation to the external surfaces of materials, which act as the active sites of these materials. However, quantification of this nanoparticle uptake is challenging. Previous studies explore the link between antimicrobial activity and surface concentration of the active component, but this is not directly visualized. Here we show a reliable method to monitor the incorporation of nanoparticles into a polymer host matrix via swell encapsulation. We show that the surface concentration of CdSe/ZnS nanoparticles can be accurately visualized through cross-sectional fluorescence imaging. Using this method, we can quantify the uptake of nanoparticles via swell encapsulation and measure the surface concentration of encapsulated particles, which is key in optimizing the activity of functional materials.

A SPION-eicosane protective coating for water soluble capsules: Evidence for on-demand drug release triggered by magnetic hyperthermia

An orally-administered system for targeted, on-demand drug delivery to the gastrointestinal (GI) tract is highly desirable due to the high instances of diseases of that organ system and harsh mechanical and physical conditions any such system has to endure. To that end, we present an iron oxide nanoparticle/wax composite capsule coating using magnetic hyperthermia as a release trigger. The coating is synthesised using a simple dip-coating process from pharmaceutically approved materials using a gelatin drug capsule as a template. We show that the coating is impervious to chemical conditions within the GI tract and is completely melted within two minutes when exposed to an RF magnetic field under biologically-relevant conditions. The overall simplicity of action, durability and non-toxic and inexpensive nature of our system demonstrated herein are key for successful drug delivery systems.

On-demand, magnetic hyperthermia-triggered drug delivery: optimisation for the GI tract

An orally-administered vehicle for targeted on-demand delivery to the gastrointestinal tract is presented. Hyperthermia is induced from an external AC magnetic field to melt a super paramagnetic iron oxide nanoparticle wax composite coating and hence release the capsule content.

Superhydrophobic Au/polymer nanocomposite films via AACVD/swell encapsulation tandem synthesis procedure

A synthetic route is presented for creating well-attached Au/polymer nanocomposite thin films on glass which exhibit superhydrophobicity.

Direct and continuous synthesis of VO2 nanoparticles

Monoclinic VO2 nanoparticles are of interest due to the material's thermochromic properties, however, direct synthesis routes to VO2 nanoparticles are often inaccessible due to the high synthesis temperatures or long reaction times required. Herein, we present a two-step synthesis route for the preparation of monoclinic VO2 nanoparticles using Continuous Hydrothermal Flow Synthesis (CHFS) followed by a short post heat treatment step. A range of particle sizes, dependent on synthesis conditions, were produced from 50 to 200 nm by varying reaction temperatures and the residence times in the process. The nanoparticles were characterised by powder X-ray diffraction, Raman and UV/Vis spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). The nanoparticles were highly crystalline with rod and sphere-like morphologies present in TEM micrographs, with the size of both the rod and spherical particles being highly dependent on both reaction temperature and residence time. SEM micrographs showed the surface of the powders produced from the CHFS process to be highly uniform. The samples were given a short post synthesis heat treatment to ensure that they were phase pure monoclinic VO2, which led to them exhibiting a large and reversible switch in optical properties (at near-IR wavelengths), which suggests that if such materials can be incorporated into coatings or in composites, they could be used for fenestration in architectural applications.

Bi-phasic titanium dioxide nanoparticles doped with nitrogen and neodymium for enhanced photocatalysis

Bi-phasic or multi-phasic composite nanoparticles for use in photocatalysis have been produced by a new synthetic approach. Sol-gel methods are used to deposit multiple layers of active material onto soluble substrates. In this work, a layer of rutile (TiO2) was deposited onto sodium chloride pellets followed by an annealing step and a layer of anatase. After dissolving the substrate, bi-phasic nanoparticles containing half anatase and half rutile TiO2; with "Janus-like" characteristics are obtained. Nitrogen and neodymium doping of the materials were observed to enhance the photocatalytic properties both under UV and white light irradiation. The unique advantage of this synthetic method is the ability to systematically dope separate sides of the nanoparticles. Nitrogen doping was found to be most effective on the anatase side of the nanoparticle while neodymium was found to be most effective on the rutile side. Rhodamine B dye was effectively photodegraded by co-doped particles under white light.

Functionalised gold and titania nanoparticles and surfaces for use as antimicrobial coatings

We report the preparation, characterisation and antimicrobial functional testing of various titanium dioxide and gold modified titanium dioxide nanoparticles embedded into a polysiloxane polymer by a swell dip-coating procedure. We show that the surfaces are effective in killing both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria under different lighting conditions. The presence of the nanoparticles was of critical importance in improving the functional properties of the surface. These materials have the potential to reduce hospital-acquired infection, by killing bacteria on the polymer surface.

Prolonging the circulatory retention of SPIONs using dextran sulfate: in vivo tracking achieved by functionalisation with near-infrared dyes

The rapid reticuloendothelial system (RES) mediated clearance of superparamagnetic iron oxide nanoparticles (SPIONs) from circulation is considered a major limitation of their clinical utility. We aimed to address this by using dextran sulfate 500 (DSO4 500), a Kupffer cell blocking agent, to prolong SPIONs circulatory time. Blood concentrations of SPIONs are difficult to quantify due to the presence of haemoglobin. We therefore developed methods to functionalise SPIONs with near-infrared (NIR) dyes in order to trace their biodistribution. Two SPIONs were investigated: Nanomag®-D-spio-NH(2) and Ferucarbotran. Nanomag®-D-spio-NH(2) was functionalised using NHS (N-hydroxysuccinimide) ester NIR dye and Ferucarbotran was labelled using periodate oxidation followed by reductive amination or a combination of EDC (ethyl(dimethylaminopropyl) carbodiimide )/NHS and click chemistries. Stability after conjugation was confirmed by dynamic light scattering (DLS), superconducting quantum interference device (SQUID) and transmission electron microscopy (TEM). In vivo experiments with the functionalised SPIONs showed a significant improvement in SPIONs blood concentrations in mice pre-treated with dextran sulfate sodium salt 500 (DSO4 500).

Lethal photosensitisation of Staphylococcus aureus and Escherichia coli using crystal violet and zinc oxide-encapsulated polyurethane

Bactericidal polymer surfaces were prepared by crystal violet and ZnO nanoparticle encapsulation, demonstrating 99.9% dark kill ofE. coli.

Nanoparticle–sulphur “inverse vulcanisation” polymer composites

Sulfur based mouldable nanocomposite polymers by “inverse vulcanisation”. Functional materials from waste.

Organic–inorganic hybrid materials: nanoparticle containing organogels with myriad applications

Remouldable, recyclable, hybrid materials from a low molecular weight organogelator and nanomaterials have diverse practical applications.

A low cost synthesis method for functionalised iron oxide nanoparticles for magnetic hyperthermia from readily available materials

The synthesis of iron oxide nanocrystals from reagents taken from high street sources using thermal decomposition of an iron–fatty acid precursor in a high boiling point solvent in the presence of surfactants is presented. The nanocrystals were characterised using a variety of techniques including: electron microscopy, X-ray dispersive spectroscopy, infrared spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and magnetometry. Thermogravimetric analysis (TGA) is also used to compare the decomposition behaviour of iron oleate and iron palmitate, our nanoparticle precursors. The nanoparticles also exhibit shape anisotropy when prepared under optimum conditions. We show that these nanoparticles have potential in magnetic hyperthermia after transfer to aqueous media via an amphiphilic polymer.

Copper-doped CdSe/ZnS quantum dots: controllable photoactivated copper(I) cation storage and release vectors for catalysis

The first photoactivated doped quantum dot vector for metal-ion release has been developed. A facile method for doping copper(I) cations within ZnS quantum dot shells was achieved through the use of metal-dithiocarbamates, with Cu⁺ ions elucidated by X-ray photoelectron spectroscopy. Photoexcitation of the quantum dots has been shown to release Cu⁺ ions, which was employed as an effective catalyst for the Huisgen [3+2] cycloaddition reaction. The relationship between the extent of doping, catalytic activity, and the fluorescence quenching was also explored.

Superhydrophobic photocatalytic surfaces through direct incorporation of titania nanoparticles into a polymer matrix by aerosol assisted chemical vapor deposition

A new class of superhydrophobic photocatalytic surfaces that are self-cleaning through light-induced photodegradation and the Lotus effect are presented. The films are formed in a single-step aerosol-assisted chemical vapor deposition (AACVD) process. The films are durable and show no degradation on continuous exposure to UV-C radiation.

Autosomal dominant polycystic kidney disease: new information for genetic counselling

We evaluated the accuracy of ultrasonographic diagnosis of autosomal dominant polycystic kidney disease (ADPKD) and factors influencing its prognosis in members of 17 Newfoundland families originally described in 1984. In 10 families showing genetic linkage between ADPKD and markers for the PKD1 locus, rates of false negative ultrasonographic diagnosis are estimated as 36% below the age of 10 years and 8% or less thereafter, comparable with findings of genetic linkage studies of a subset of family members. At ages above 30 years, false negative ultrasonographic diagnosis of PKD1 disease is unlikely. In 2 families in which ADPKD is not co-inherited with PKD1 markers, only 11% of members aged less than 30 years had kidney cysts. The mean (SE) age of onset of ESRD is 56.3 (1.8) years for persons with the PKD1 form of ADPKD, and 68.7 (1.7) years for affected members of families in which ADPKD is not co-inherited with PKD1 markers (P = 0.01). In the PKD1 families, age of onset of end stage renal disease (ESRD) was unrelated to the sex of the affected individual but was earlier in persons inheriting the disease from their mothers than from their fathers (50.5 vs. 64.8 years, P = 0.004), consistent with an influence of genetic imprinting on disease progression. In females with a PKD1 mutation, onset of ESRD was not influenced by parity. In PKD1 families, resemblance in age of onset of ESRD was apparent; variation was less within than between families (F = 13.0, P less than 0.0001), and risk of false negative ultrasonographic diagnosis appears largely restricted to families in which ESRD occurs relatively late.

The diagnosis and prognosis of autosomal dominant polycystic kidney disease

BACKGROUND

Autosomal dominant polycystic kidney disease is usually caused by a mutant gene at the PKD1 locus on the short arm of chromosome 16, but in about 4 percent of families with the disorder it is caused by unknown mutations elsewhere in the genome. The natural course of the disease in both genetic forms is not well characterized.

METHODS

We studied 17 families with autosomal dominant polycystic kidney disease to compare presymptomatic diagnosis by ultrasonography with diagnosis by genetic-linkage studies and to relate clinical variation of the disease to whether the PKD1 mutation was implicated.

RESULTS

In 10 families the disorder was found to cosegregate with polymorphic DNA markers flanking the PKD1 locus, in 2 families it did not, and in 5 families linkage could not be determined. In the 10 families with the PKD1 mutation, 46 percent of the members less than 30 years old who had a 50 percent risk of inheriting a mutation had renal cysts, as compared with 11 percent of the members of the two families without linkage (P less than 0.001). In the PKD1 families, all 67 diagnoses made by ultrasonography were confirmed by determination of the genotype as inferred from linkage. Forty of 48 members (83 percent) less than 30 years old who inherited the PKD1 mutation had renal cysts. All 27 members 30 years old or older who inherited the mutation had renal cysts, suggesting that the probability of a false negative diagnosis did not exceed 0.13 in this age group (P less than 0.05). The mean (+/- SE) age at the onset of end-stage renal disease among members of the PKD1 families was 56.7 +/- 1.9 years, as compared with 69.4 +/- 1.7 years among members with cysts in the families without linkage (P = 0.0025). Hypertension and renal impairment were less frequent and occurred later in the families without the PKD1 mutation.

CONCLUSIONS

At present, in most persons with a 50 percent risk of autosomal dominant polycystic kidney disease, imaging techniques are the only mode of reaching a diagnosis before symptoms appear. In such persons a negative ultrasonographic study during early adult life indicates that the likelihood of inheriting a PKD1 mutation is small. In the few who inherit a non-PKD1 mutation for polycystic kidney disease, renal failure is likely to occur relatively late in life.

Regional localization of the autosomal dominant polycystic kidney disease locus

The localization of the autosomal dominant polycystic kidney disease locus (PKD1) within an array of anonymous polymorphic DNA sequences on chromosome 16 band p13 was determined by multipoint mapping. Nine polymorphic DNA markers, including two hypervariable sequences, were used to study 19 PKD1 and 21 reference families. PKD1 was found to lie proximal to the 3' and 5' hypervariable regions of alpha-globin and distal to the anonymous sequence CRI-0327. Somatic cell hybrid mapping places PKD1 within the region 16p13.11-16pter. The availability of an array of linked markers which bracket the PKD1 locus provides a framework for further attempts to identify the PKD1 gene and offers an improved method of presymptomatic diagnosis of the disease.

Inbreeding in outport Newfoundland

We investigated inbreeding in 3 outport Newfoundland study areas in which persistent genetic isolation was demonstrated previously. The inbreeding coefficient of every person born in each area was calculated from reconstructed pedigree data. The average inbreeding coefficient for persons born between 1960 and 1979 is 0.0032 in Trepassey Parish (southern Avalon Peninsula), 0.0171 for a group of communities on the west coast of the Great Northern Peninsula, and 0.0007 for southeastern Labrador. Average inbreeding of these populations was higher earlier in this century. Averages are high compared to those reported for other populations, consistent with genetic isolation. Coefficients of kinship were calculated for large samples of pairs of births in each study area, and frequency distributions of inbreeding coefficients compared with frequency distributions of kinship coefficients, to evaluate random and nonrandom mating with respect to consanguinity. These comparisons show that matings between unrelated individuals are more frequent than expected, that matings between first cousins are not strongly avoided in 2 of the 3 study areas, that matings between first cousins once removed are favored, and that matings between distantly related individuals are becoming more frequent. To gain an impression of the potential contribution of inbreeding to the prevalence of recessive disease, we calculated indirect estimates of the expected excess of prereproductive mortality due to inbreeding. These estimates are 15% for Trepassey Parish, 49% for the West Coast study area, and 2% for southeastern Labrador. It is unlikely that genetic isolation of outport Newfoundland populations will decrease. Elevated prevalences of recessive disease, due primarily to matings between persons unaware of their distant consanguinity, therefore require consideration in health care planning in Newfoundland.

How the method used to measure refractive error is expected to affect statistical results

Values of refractive error (RE) observed for subjects and groups depend on the degree to which the measurement method used relaxes accommodation. This affects statistics calculated on RE measurements in predictable ways. Comparing noncycloplegic (NC) with cycloplegic (C) methods, myopia is expected to be more frequent, differences between group means should be less, and correlations and regressions relating RE to other variables may be reduced slightly. Tests based on the categorization of RE will show weaker associations with putative influencing variables. The implications of this are discussed for comparing published studies and choosing measurement methods in epidemiological and genetic studies.

Persistent genetic isolation in outport Newfoundland

The historical development of genetic isolation has been evaluated for three outport Newfoundland study areas. An attempt was made to ascertain all livebirths in each study area, and determine the parentage of each. Data from records of baptism and marriage were used for this, supplemented with other historical and ethnographic information. Parent-offspring migration was used as a measure of genetic exchange between subpopulations within study areas, and gene flow into the study areas. Currently, 1-8% of parents originate outside the study areas; these rates are low compared to earlier periods, and compared to present-day rates for European isolate populations. Average kinship was estimated, to measure genetic relatedness within and between subpopulations of each area and the potential for random inbreeding; these values, which are minimum estimates, are now at historically high levels. Increased migration into the study areas, which would decrease average kinship, is not likely. Thus, any regionally or locally elevated frequencies of deleterious alleles will persist, and must be taken into account in providing genetic counseling and evaluating the utility of local screening programs.

The burden of genetically determined eye disease

We determined the underlying aetiology of blindness for the registered blind population of the Province of Newfoundland and Labrador. In both 1981 and 1984 single-gene disorders accounted for 30% of total blindness and congenital defects for another 10-11%. Genetically determined conditions, diabetes, and senile macular degeneration (SMD) were the three leading causes of registration in each year, 1980-4. We calculated mean ages of registration and mean ages of death over the last four years for five major aetiological groups. Patients with genetic conditions were registered at a much younger age and had a correspondingly longer duration of blindness (21 years as compared with 5 years for either diabetes or SMD). Total 'person-years of blindness' was then calculated from the product of this duration of blindness and the total numbers registered in each group. This index shows that the overall individual and population impact of monogenic blindness is overwhelmingly greater than that of other causes (6849 person-years compared with 270 for diabetes and 430 for SMD). In view of this frequency and duration of monogenic blindness, and also of the substantial hereditary liability to relatively common causes of blindness such as glaucoma, diabetic retinopathy, and high myopia, we suggest that more attention needs to be paid to elucidating the genetic contribution to blindness.

Heterogeneity of systemic lupus erythematosus elucidated by cluster analysis. The influence of HLA

For 75 patients with systemic lupus erythematosus (SLE), 39 laboratory and clinical characteristics, including HLA-A, B, C and DR typing, were analysed using a cluster analysis technique. Three groups were identified. Group I (46 patients) was characterized by infrequently severe disease, good response to therapy and infrequent multisystem involvement. Group II (24 patients) was characterized by a severe course of disease (although the tendency to remit after therapy was not unusual), and frequently, renal involvement and pericarditis. Group III (5 patients) was characterized by more severe renal disease. Of the 75 patients studied, 38.7% possessed HLA-DR3, compared to 17.4% of controls. Group I patients did not differ from controls but 80% of Group II patients and 4/5 Group III patients had DR3. Cluster analysis identifies subsets of SLE patients who show marked differences in disease course and severity, correlated with possession of the HLA B8, DR3 phenotype.