QCM-D Investigations on Cholesterol-DNA Tethering of Liposomes to Microbubbles for Therapy.

Lipid-shelled microbubbles (MBs) offer potential as theranostic agents, capable of providing both contrast enhancement in ultrasound imaging as well as a route for triggered drug release and improved localized drug delivery. A common motif in the design of such therapeutic vehicles is the attachment of the drug carrier, often in the form of liposomes, to the microbubble. Traditionally, such attachments have been based around biotin-streptavidin and maleimide-PDP chemistries.

Horizon: Microfluidic platform for the production of therapeutic microbubbles and nanobubbles.

Microbubbles (MBs) have a multitude of applications including as contrast agents in ultrasound imaging and as therapeutic drug delivery vehicles, with further scope for combining their diagnostic and therapeutic properties (known as theranostics). MBs used clinically are commonly made by mechanical agitation or sonication methods, which offer little control over population size and dispersity. Furthermore, clinically used MBs are yet to be used therapeutically and further research is needed to develop these theranostic agents.

Freeze-Dried Therapeutic Microbubbles: Stability and Gas Exchange.

Microbubbles (MBs) are widely used as contrast enhancement agents for ultrasound imaging and have the potential to enhance therapeutic delivery to diseases such as cancer. Yet, they are only stable in solution for a few hours to days after production, which limits their potential application. Freeze-drying provides long-term storage, ease of transport, and consistency in structure and composition, thereby facilitating their use in clinical settings.

Ultrasound-triggered therapeutic microbubbles enhance the efficacy of cytotoxic drugs by increasing circulation and tumor drug accumulation and limiting bioavailability and toxicity in normal tissues.

Most cancer patients receive chemotherapy at some stage of their treatment which makes improving the efficacy of cytotoxic drugs an ongoing and important goal. Despite large numbers of potent anti-cancer agents being developed, a major obstacle to clinical translation remains the inability to deliver therapeutic doses to a tumor without causing intolerable side effects. To address this problem, there has been intense interest in nanoformulations and targeted delivery to improve cancer outcomes.

A bioinspired peptide matrix for the detection of 2,4,6-trinitrotoluene (TNT).

A novel peptide-based three-dimensional probe called "peptide matrix," inspired by the antibody paratope region, was fabricated on a surface plasmon resonance (SPR) sensor chip to enhance the sensitivity of detecting the explosive 2,4,6-trinitrotoluene (TNT). Although peptide aptamer is an attractive candidate for a molecular recognition probe because of its ease of synthesis and chemical stability, it still has difficulty in applying to highly sensitive (i.e.

Controlling the fluorescence and room-temperature phosphorescence behaviour of carbon nanodots with inorganic crystalline nanocomposites.

There is a significant drive to identify alternative materials that exhibit room temperature phosphorescence for technologies including bio-imaging, photodynamic therapy and organic light-emitting diodes. Ideally, these materials should be non-toxic and cheap, and it will be possible to control their photoluminescent properties. This was achieved here by embedding carbon nanodots within crystalline particles of alkaline earth carbonates, sulphates and oxalates.

A highly reactive precursor in the iron sulfide system.

Iron sulfur (Fe-S) phases have been implicated in the emergence of life on early Earth due to their catalytic role in the synthesis of prebiotic molecules. Similarly, Fe-S phases are currently of high interest in the development of green catalysts and energy storage. Here we report the synthesis and structure of a nanoparticulate phase (FeS) that is a necessary solid-phase precursor to the conventionally assumed initial precipitate in the iron sulfide system, mackinawite.

Enhanced Tubulation of Liposome Containing Cardiolipin by MamY Protein from Magnetotactic Bacteria.

Lipid tubules are of particular interest for many potential applications in nanotechnology. Among various lipid tubule fabrication techniques, the morphological regulation of membrane structure by proteins mimicking biological processes may provide the chances to form lipid tubes with highly tuned structures. Magnetotactic bacteria synthesize magnetosomes (a unique prokaryotic organelle comprising a magnetite crystal within a lipid envelope).

The influence of intercalating perfluorohexane into lipid shells on nano and microbubble stability.

Microbubbles are potential diagnostic and therapeutic agents. In vivo stability is important as the bubbles are required to survive multiple passages through the heart and lungs to allow targeting and delivery. Here we have systematically varied key parameters affecting microbubble lifetime to significantly increase in vivo stability.

Phospholipid dependent mechanism of smp24, an α-helical antimicrobial peptide from scorpion venom.

Determining the mechanism of action of antimicrobial peptides (AMPs) is critical if they are to be developed into the clinical setting. In recent years high resolution techniques such as atomic force microscopy (AFM) have increasingly been utilised to determine AMP mechanism of action on planar lipid bilayers and live bacteria. Here we present the biophysical characterisation of a prototypical AMP from the venom of the North African scorpion Scorpio maurus palmatus termed Smp24.

On-chip preparation of nanoscale contrast agents towards high-resolution ultrasound imaging.

Micron-sized lipid-stabilised bubbles of heavy gas have been utilised as contrast agents for diagnostic ultrasound (US) imaging for many years. Typically bubbles between 1 and 8 μm in diameter are produced to enhance imaging in US by scattering sound waves more efficiently than surrounding tissue. A potential area of interest for Contrast Enhanced Ultrasound (CEUS) are bubbles with diameters <1 μm or 'nanobubbles.

Self-assembly of actin scaffolds on lipid microbubbles.

Microbubbles offer unique properties as combined carriers of therapeutic payloads and diagnostic agents. Here we report on the development of novel microbubble architectures that in addition to the usual lipid shell have an actin cytoskeletal cortex assembled on their exterior. We show, using atomic force microscopy that this biomimetic coating creates a thin mesh that allows tuning of the mechanical properties of microbubbles and that the nature of actin assembly is determined by the fluidity of the lipid layer.

Actin assembly at model-supported lipid bilayers.

We report on the use of supported lipid bilayers to reveal dynamics of actin polymerization from a nonpolymerizing subphase via cationic phospholipids. Using varying fractions of charged lipid, lipid mobility, and buffer conditions, we show that dynamics at the nanoscale can be used to control the self-assembly of these structures. In the case of fluid-phase lipid bilayers, the actin adsorbs to form a uniform two-dimensional layer with complete surface coverage whereas gel-phase bilayers induce a network of randomly oriented actin filaments, of lower coverage.

Expanding 3D geometry for enhanced on-chip microbubble production and single step formation of liposome modified microbubbles.

Micron sized, lipid stabilized bubbles of gas are of interest as contrast agents for ultra-sound (US) imaging and increasingly as delivery vehicles for targeted, triggered, therapeutic delivery. Microfluidics provides a reproducible means for microbubble production and surface functionalisation. In this study, microbubbles are generated on chip using flow-focussing microfluidic devices that combine streams of gas and liquid through a nozzle a few microns wide and then subjecting the two phases to a downstream pressure drop.

Aβ42 oligomers, but not fibrils, simultaneously bind to and cause damage to ganglioside-containing lipid membranes.

Aβ (amyloid-β peptide) assembles to form amyloid fibres that accumulate in senile plaques associated with AD (Alzheimer's disease). The major constituent, a 42-residue Aβ, has the propensity to assemble and form soluble and potentially cytotoxic oligomers, as well as ordered stable amyloid fibres. It is widely believed that the cytotoxicity is a result of the formation of transient soluble oligomers.

Concentrating membrane proteins using asymmetric traps and AC electric fields.

Membrane proteins are key components of the plasma membrane and are responsible for control of chemical ionic gradients, metabolite and nutrient transfer, and signal transduction between the interior of cells and the external environment. Of the genes in the human genome, 30% code for membrane proteins (Krogh et al. J.

Effect of the structure of cholesterol-based tethered bilayer lipid membranes on ionophore activity.

Tethered bilayer lipid membranes (tBLM) are formed on 1) pure tether lipid triethyleneoxythiol cholesterol (EO(3)C) or on 2) mixed self-assembled monolayers (SAMs) of EO(3)C and 6-mercaptohexanol (6MH). While EO(3)C is required to form a tBLM with high resistivity, 6MH dilutes the cholesterol content in the lower leaflet of the bilayer forming ionic reservoirs required for submembrane hydration. Here we show that these ionic reservoirs are required for ion transport through gramicidin or valinomycin, most likely due to the thermodynamic requirements of ions to be solvated once transported through the membrane.

In vitro biosynthesis of bacterial peptidoglycan using D-Cys-containing precursors: fluorescent detection of transglycosylation and transpeptidation.

Peptidoglycan precursors containing D-Cys at position 4 were polymerised to form a synthetic peptidoglycan layer, which could be fluorescently labelled, providing a new method to monitor peptidoglycan transglycosylation and transpeptidation.

Minimal F-actin cytoskeletal system for planar supported phospholipid bilayers.

Preferential binding of F-actin to lipid bilayers containing ponticulin was investigated on both planar supported bilayers and on a cholesterol-based tethering system. The transmembrane protein ponticulin in Dictyostelium discoideum is known to provide a direct link between the actin cytoskeleton and the cell membrane ( Wuestehube, L. J.

Native E. coli inner membrane incorporation in solid-supported lipid bilayer membranes.

Solid-supported bilayer lipid membranes (SBLMs) containing membrane protein have been generated through a simple lipid dilution technique. SBLM formation from mixtures of native Escherichia coli bacterial inner membrane (IM) vesicles diluted with egg phosphatidylcholine (egg PC) vesicles has been explored with dissipation enhanced quartz crystal microbalance (QCM-D), atomic force microscopy (AFM), attenuated total internal-reflection Fourier-transform infrared spectroscopy (ATR-FTIR), and fluorescence recovery after photobleaching (FRAP). QCM-D studies reveal that SBLM formation from vesicle mixtures ranging between 0% and 100% IM can be divided into two regimes.

Site-directed conjugation of "clicked" glycopolymers to form glycoprotein mimics: binding to mammalian lectin and induction of immunological function.

Synthesis of well-defined neoglycopolymer-protein biohybrid materials and a preliminary study focused on their ability of binding mammalian lectins and inducing immunological function is reported. Crucial intermediates for their preparation are well-defined maleimide-terminated neoglycopolymers (M(n) = 8-30 kDa; M(w)/M(n) = 1.20-1.

Self-assembly of actin scaffolds at ponticulin-containing supported phospholipid bilayers.

Phospholipid vesicles containing ponticulin have been used to form solid supported and tethered bilayer lipid membranes. The ponticulin serves as both a nucleation site for actin polymerization as well as a binding site for F-actin. Studies of F-actin binding to such bilayers have demonstrated the formation of an in vitro actin scaffold.