Publications by authors named "Alexandra Rollett"

The folate antagonist methotrexate is a cytotoxic drug used in the treatment of several cancer types. The entry of methotrexate into the cell is mediated by two main transport systems: the reduced folate carrier and membrane-associated folate receptors. These transporters differ considerably in their mechanism of (anti)folate uptake, substrate specificity, and tissue specificity.

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There is a strong need of point-of-care diagnostics for early detection of wound infection. In this study, substrates based on functionalized chitosan were developed for visual detection of elevated lysozyme activity, an infection biomarker in wound fluids. For efficient hydrolysis by lysozyme, N-acetyl chitosan with a final degree of acetylation of around 50% was synthesized.

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Chito-oligosaccharides (COSs) are bioactive molecules with interesting characteristics; however, their exploitation is still restricted due to limited amounts accessible with current production strategies. Here we present a strategy for the production of COSs based on hydrolysis of chitosan by using readily available glycosidases. Cellobiohydrolases (EC 3.

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Increasing prevalence of chronic wounds and microbial infection constitute a severe health challenge. The situation is further complicated by emerging multidrug resistance making the treatment of infections increasingly difficult. Here, a novel antimicrobial system based on in situ release of hydrogen peroxide (H2O2) by cellobiose dehydrogenase (CDH) immobilized on chitosan (CTS) particles is described.

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Bovine serum albumin (BSA) nanoemulsions were produced by high pressure homogenization with a tri-block copolymer (Poloxamer 407), which presents a central hydrophobic chain of polyoxypropylene (PPO) and two identical lateral hydrophilic chains of polyethylene glycol (PEG). We observed a linear correlation between tri-block copolymer concentration and size - the use of 5mg/mL of Poloxamer 407 yields nanoemulsions smaller than 100nm. Molecular dynamics and fluorescent tagging of the tri-block copolymer highlight their mechanistic role on the size of emulsions.

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Specific folate receptors are abundantly overexpressed in chronically activated macrophages and in most cancer cells. Directed folate receptor targeting using liposomes is usually achieved using folate linked to a phospholipid or cholesterol anchor. This link is formed using a large spacer like polyethylene glycol.

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Introduction: Genetically engineered biomaterials are useful for controlled delivery owing to their rational design, tunable structure-function, biocompatibility, degradability and target specificity. Silk-elastin-like proteins (SELPs), a family of genetically engineered recombinant protein polymers, possess these properties. Additionally, given the benefits of combining semi-crystalline silk-blocks and elastomeric elastin-blocks, SELPs possess multi-stimuli-responsive properties and tunability, thereby becoming promising candidates for targeted cancer therapeutics delivery and controlled gene release.

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The chronic autoimmune disorder rheumatoid arthritis (RA) affects millions of adults and children every year. Chronically activated macrophages secreting enzymes and inflammatory cytokines play a key role in RA. Distinctive marker molecules on the macrophage surface could be used to design a targeted drug delivery device for the treatment of RA without affecting healthy cells and tissues.

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Activated synovial macrophages play a key role in Rheumatoid Arthritis (RA). Recent studies have shown that folate receptor beta (FRβ) is specifically expressed by activated macrophages. Therefore a folate-based nanodevice would provide the possibility of delivering therapeutic agents to activated macrophages without affecting normal cells and tissues.

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Polysaccharide acid (PSA) based devices (consisting of alginic acid and polygalacturonic acid) were investigated for the detection of contaminating microorganisms. PSA-CaCl(2) hydrogel systems were compared to systems involving covalent cross-linking of PSA with glycidylmethacrylate (PSA-GMA) which was confirmed with Fourier Transformed Infrared (FTIR) analysis. Incubation of PSA-CaCl(2) and PSA-GMA beads loaded with Alizarin as a model ingredient with trigger enzymes (polygalacturonases or pectate lyases) or bacteria lead to a smoothening of the surface and exposure of Alizarin according to Environmental Scanning Electron Microscopy (ESEM) analysis.

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New complexes of pyridine-bis(oxazoline) derivatized with -H, -OMe, and -Br at the para position of the pyridine ring with Eu(III) and Tb(III) have been isolated. These are highly luminescent in the solid state, regardless of the ligand-to-metal ratio. Several of the metal complexes were isolated and characterized by single crystal X-ray diffraction, showing the rich diversity of structures that can be obtained with this family of ligands.

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Immobilisation of enzyme substrates is a powerful tool in the detection of enzymes in the chemosphere and the environment. A siloxane based strategy for the covalent immobilisation of oxidoreductase and protease substrates was developed involving activation of silica gel and polyethylene terephthalate (PET) as model carriers with (3-aminopropyl)-triethoxysilane or (3-mercaptopropyl)-trimethoxysilane (APTS, MPTS). Ferulic acid and L-Leucine-p-nitroanilide, Gly-Phe p-nitroanilide (GPpNA) and N-Succinyl-Ala-Ala-Pro-Leu p-nitroanilide (SAAPLpNA) as laccase and protein substrates, respectively, were covalently attached using glutaraldehyde or carbodiimide based cross-linking strategies.

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