Short bowel syndrome (SBS) is a devastating disorder with both short- and long-term implications ... more Short bowel syndrome (SBS) is a devastating disorder with both short- and long-term implications for patients. Unfortunately, the prevalence of SBS has doubled over the past 40 years. Broadly speaking, the etiology of SBS can be categorized as congenital or secondary, the latter typically due to extensive small bowel resection following diseases of the small intestine, e.g., necrotizing enterocolitis, Hirschsprung’s disease or intestinal atresia. As of yet, no cure exists, thus, conservative treatment, primarily parenteral nutrition (PN), is the first-line therapy. In some cases, weaning from PN is not possible and operative therapy is required. The invention of the longitudinal intestinal lengthening and tailoring (LILT or Bianchi) procedure in 1980 was a major step forward in patient care and spawned further techniques that continue to improve lives for patients with severe SBS (e.g., double barrel enteroplasty, serial transverse enteroplasty, etc.). With this review, we aim to pr...
Langmuir : the ACS journal of surfaces and colloids, Jan 2, 2018
The ability to control supramolecular and macroscopic self-assembly and disassembly holds great p... more The ability to control supramolecular and macroscopic self-assembly and disassembly holds great potential for responsive, reversible adhesives that can efficiently broker stresses accumulated between two surfaces. Here, cucurbit[8]uril is used to directly adhere two functionalized mica substrates creating surface-surface interactions that are held together through photo-reversible CB[8] heteroternary complexes. Comparison of single molecule, bulk and macroscopic adhesion behavior give insight into cooperativity and stress dissipation in dynamic adhesive systems.
Langmuir : the ACS journal of surfaces and colloids, Feb 5, 2017
Cucurbit[8]uril (CB[8]) heteroternary complexes display certain characteristics making them well-... more Cucurbit[8]uril (CB[8]) heteroternary complexes display certain characteristics making them well-suited for molecular level adhesives. In particular, the ability to control adhesion through careful choice of host-guest binding pairs enables specific, fully reversible adhesion. Understanding the effect of the environment on the adhesive system is also critical when developing new molecular level adhesives. Here we explore the binding forces involved in the methyl viologen · CB[8] · napthol heteroternary complex using single-molecule force spectroscopy (SMFS) under a variety of conditions. From SMFS, the interaction of a single ternary complex was found to be in the region of 140 pN. Additionally, a number of surface interactions could be readily differentiated using the SMFS technique allowing for a deeper understanding of the dynamic heteroternary CB[8] system on the single-molecule scale.
Interest in thermoresponsive materials are generating significant interest on account of the shar... more Interest in thermoresponsive materials are generating significant interest on account of the sharp and tunable temperature de-swelling transition of the polymer chain. Such materials have shown promise in drug delivery devices, sensing systems and in self-assembly. Incorporation of nanoparticles (NPs), typically through covalent attachment of the polymer chains to the NP surface, can add additional functionality and tunability to such hybrid materials. The versatility of these thermoresponsive polymer/nanoparticle materials has been shown previously, however, significant and important differences exist in the published literature between virtually identical materials. Here we use PNIPAm-AuNPs as a model system to understand the aggregation behavior of thermoresponsive polymer-coated nanoparticles made by either grafting-to or grafting-from methods. We show that, contrary to popular belief, the aggregation of PNIPAm-coated AuNPs, and likely other such materials, relies on the size an...
Proceedings of the National Academy of Sciences, 2014
Significance The preservation of cultural heritage is of widespread importance all over the world... more Significance The preservation of cultural heritage is of widespread importance all over the world. Yet the lack of development in the field of conservation treatments means the fate of some of the most culturally important artifacts in the world remain in jeopardy. In the preservation of waterlogged wooden artifacts, conservators rely almost exclusively on poly(ethylene glycol) doped with a broad-spectrum biocide. The concept of a chemotactic consolidant, one that can adapt to the artifact it is treating, as described here has never before been described for an archaeological/conservation treatment. Additionally, the cross-links holding the consolidant together are entirely reversible, resulting in a material that is a greener, safer, and sustainable alternative to current conservation strategies.
ABSTRACT Dopamine (DA) is an important biomarker for diseases and biological disorders. Existing ... more ABSTRACT Dopamine (DA) is an important biomarker for diseases and biological disorders. Existing techniques for DA detection suffer from drawbacks including low sensitivity and selectivity as well as interfering signals from non-target molecules. A simple and selective photochemical sensor for the determination of DA in a supramolecular manner is presented. This approach utilises the complexation properties of a highly fluorescent water-soluble complex of perylene bis(diimide) dye with the macrocyclic host cucurbit[8]uril. The method can be used for the determination of DA in aqueous media, with detection limits below 2 × 10− 5 M, even in the presence of known interferents including ascorbic acid and the catecholamines epinephrine and norepinepherine.
Spiropyran photochromic compounds can be switched using light exposure between a non-polar spiro ... more Spiropyran photochromic compounds can be switched using light exposure between a non-polar spiro form (SP) and a zwitterionic merocyanine form (MC) that is subject to protonation (MC-H+). It has recently been demonstrated by Walsh et al. that, under acidic conditions, electroosmotic flow (EOF) generated in vinyl based spiropyran monoliths can be modulated using light irradiation [1]. In this paper, we report a spiropyran-modified acrylate based monolith which is particularly sensitive to protonation in the MC form, producing a positively charged surface that converts to the unpolar SP form by exposure to white light. When the MC-H+ form is dominant, it produces a charged surface which enables a relatively high flow rate (up to 1.6 μl/min) to be generated under electroosmotic conditions. Upon exposure to white light, the concentration of MC-H+ decreases due to the photo-conversion to the uncharged SP form, with up to 20% reduction of the EOF. The process is reversible, and removal of...
Conserving the world’s cultural and natural heritage is considered a key contributor to achieving... more Conserving the world’s cultural and natural heritage is considered a key contributor to achieving the targets set out in the United Nation’s Sustainable Development Goals, yet how much attention do we pay to the methods we use to conserve and protect this heritage? With a specific focus on wooden objects of cultural heritage, this review discusses the current state-of-the-art in heritage conservation in terms of sustainability, sustainable alternatives to currently used consolidants, and new research directions that could lead to more sustainable consolidants in the future. Within each stage a thorough discussion of the synthesis mechanisms and/or extraction protocols, particularly for bio-based resources is provided, evaluating resource usage and environmental impact. This is intended to give the reader a better understanding of the overall sustainability of each different approach and better evaluate consolidant choices for a more sustainable approach. The challenges facing the de...
Enclosed is the raw data for the UV-Vis study that was presented in the manuscript, along with th... more Enclosed is the raw data for the UV-Vis study that was presented in the manuscript, along with the DLS data collected.
The removal of water from archaeological wooden objects for display or storage is of great import... more The removal of water from archaeological wooden objects for display or storage is of great importance to their long-term conservation. Any mechanical instability caused during drying can induce warping or cracking of the wood cells, leading to irreparable damage of the object. Drying of an object is commonly carried out in one of three ways: (i) air-drying with controlled temperature and relative humidity, (ii) drying-out of a non-aqueous solvent or (iii) freeze-drying. Recently, there has been great interest in the replacement of the standard, but limited, polyethylene glycol with biopolymers for wood conservation; however, their behaviour and action within the wood is not completely understood. Three polysaccharides—low-molar-mass (Mw) chitosan (Mw ca. 60,000 g/mol), medium-molar-mass alginate (Mw ca. 100,000 g/mol) and cellulose nanocrystals (CNCs)-are investigated in relation to their drying behaviour. The method of drying reveals a significant difference in the morphology of th...
A booming global population and the environmental impact of concrete and steel has forced constru... more A booming global population and the environmental impact of concrete and steel has forced construction engineers to expand their horizons in the search for new materials for sustainable housing. A promising solution is the use of fast-growing native woods for the construction of housing and shelter, particularly in developing countries and to quickly replace housing destroyed by natural disaster. In contrast to slower-growing species, such as wood is often of a lower construction grade and, therefore not suitable for use without further modification. Attempting to solve this issue has led to widespread research on the development of polymer-infused or -treated wood products, so-called wood polymer composites (WPCs). The extraordinary properties of WPCs have led to further research in the area of wood polymer nanocomposites (WPNCs), generally containing additional nanofillers to enhance strength. These composites provide a positive outlook not only for new wooden constructions but al...
The preservation of cultural heritage is of great importance worldwide and, as such, has been the... more The preservation of cultural heritage is of great importance worldwide and, as such, has been the focus of an increasing number of research projects in recent years. In spite of considerable efforts around the world, significant problems have arisen with the conservation of many shipwrecks. The most common issues facing conservators are structural instability upon drying and biological degradation stemming from the aquatic flora and fauna active around the excavation site. However, many important artefacts – such as the sixteenth century warship Mary Rose – also suffer from metal ion saturation from degraded bolts and fittings. In most cases Fe3+ is the greatest problem, which catalyses the production of sulfuric and oxalic acid in the waterlogged timbers, adding chemical degradation to the potential conservation issues. Moreover, the Fe3+ also feeds biological degradation by providing bacteria with an iron source for sustained growth. As such, multi-functional consolidants are grea...
A noninvasive method to assess the local monomer concentration within a wooden matrix, post monom... more A noninvasive method to assess the local monomer concentration within a wooden matrix, post monomer impregnation, by time-resolved diffuse optical spectroscopy is demonstrated. A data analysis technique for improving accuracy, which takes account of changes in the refractive index during the monomer uptake, has been employed. This technique can be potentially applied in the wood industry for the study of polymer composites as well as in cultural heritage science for noninvasively monitoring the penetration of chemical compounds used for consolidation or conservation purposes.
Short bowel syndrome (SBS) is a devastating disorder with both short- and long-term implications ... more Short bowel syndrome (SBS) is a devastating disorder with both short- and long-term implications for patients. Unfortunately, the prevalence of SBS has doubled over the past 40 years. Broadly speaking, the etiology of SBS can be categorized as congenital or secondary, the latter typically due to extensive small bowel resection following diseases of the small intestine, e.g., necrotizing enterocolitis, Hirschsprung’s disease or intestinal atresia. As of yet, no cure exists, thus, conservative treatment, primarily parenteral nutrition (PN), is the first-line therapy. In some cases, weaning from PN is not possible and operative therapy is required. The invention of the longitudinal intestinal lengthening and tailoring (LILT or Bianchi) procedure in 1980 was a major step forward in patient care and spawned further techniques that continue to improve lives for patients with severe SBS (e.g., double barrel enteroplasty, serial transverse enteroplasty, etc.). With this review, we aim to pr...
Langmuir : the ACS journal of surfaces and colloids, Jan 2, 2018
The ability to control supramolecular and macroscopic self-assembly and disassembly holds great p... more The ability to control supramolecular and macroscopic self-assembly and disassembly holds great potential for responsive, reversible adhesives that can efficiently broker stresses accumulated between two surfaces. Here, cucurbit[8]uril is used to directly adhere two functionalized mica substrates creating surface-surface interactions that are held together through photo-reversible CB[8] heteroternary complexes. Comparison of single molecule, bulk and macroscopic adhesion behavior give insight into cooperativity and stress dissipation in dynamic adhesive systems.
Langmuir : the ACS journal of surfaces and colloids, Feb 5, 2017
Cucurbit[8]uril (CB[8]) heteroternary complexes display certain characteristics making them well-... more Cucurbit[8]uril (CB[8]) heteroternary complexes display certain characteristics making them well-suited for molecular level adhesives. In particular, the ability to control adhesion through careful choice of host-guest binding pairs enables specific, fully reversible adhesion. Understanding the effect of the environment on the adhesive system is also critical when developing new molecular level adhesives. Here we explore the binding forces involved in the methyl viologen · CB[8] · napthol heteroternary complex using single-molecule force spectroscopy (SMFS) under a variety of conditions. From SMFS, the interaction of a single ternary complex was found to be in the region of 140 pN. Additionally, a number of surface interactions could be readily differentiated using the SMFS technique allowing for a deeper understanding of the dynamic heteroternary CB[8] system on the single-molecule scale.
Interest in thermoresponsive materials are generating significant interest on account of the shar... more Interest in thermoresponsive materials are generating significant interest on account of the sharp and tunable temperature de-swelling transition of the polymer chain. Such materials have shown promise in drug delivery devices, sensing systems and in self-assembly. Incorporation of nanoparticles (NPs), typically through covalent attachment of the polymer chains to the NP surface, can add additional functionality and tunability to such hybrid materials. The versatility of these thermoresponsive polymer/nanoparticle materials has been shown previously, however, significant and important differences exist in the published literature between virtually identical materials. Here we use PNIPAm-AuNPs as a model system to understand the aggregation behavior of thermoresponsive polymer-coated nanoparticles made by either grafting-to or grafting-from methods. We show that, contrary to popular belief, the aggregation of PNIPAm-coated AuNPs, and likely other such materials, relies on the size an...
Proceedings of the National Academy of Sciences, 2014
Significance The preservation of cultural heritage is of widespread importance all over the world... more Significance The preservation of cultural heritage is of widespread importance all over the world. Yet the lack of development in the field of conservation treatments means the fate of some of the most culturally important artifacts in the world remain in jeopardy. In the preservation of waterlogged wooden artifacts, conservators rely almost exclusively on poly(ethylene glycol) doped with a broad-spectrum biocide. The concept of a chemotactic consolidant, one that can adapt to the artifact it is treating, as described here has never before been described for an archaeological/conservation treatment. Additionally, the cross-links holding the consolidant together are entirely reversible, resulting in a material that is a greener, safer, and sustainable alternative to current conservation strategies.
ABSTRACT Dopamine (DA) is an important biomarker for diseases and biological disorders. Existing ... more ABSTRACT Dopamine (DA) is an important biomarker for diseases and biological disorders. Existing techniques for DA detection suffer from drawbacks including low sensitivity and selectivity as well as interfering signals from non-target molecules. A simple and selective photochemical sensor for the determination of DA in a supramolecular manner is presented. This approach utilises the complexation properties of a highly fluorescent water-soluble complex of perylene bis(diimide) dye with the macrocyclic host cucurbit[8]uril. The method can be used for the determination of DA in aqueous media, with detection limits below 2 × 10− 5 M, even in the presence of known interferents including ascorbic acid and the catecholamines epinephrine and norepinepherine.
Spiropyran photochromic compounds can be switched using light exposure between a non-polar spiro ... more Spiropyran photochromic compounds can be switched using light exposure between a non-polar spiro form (SP) and a zwitterionic merocyanine form (MC) that is subject to protonation (MC-H+). It has recently been demonstrated by Walsh et al. that, under acidic conditions, electroosmotic flow (EOF) generated in vinyl based spiropyran monoliths can be modulated using light irradiation [1]. In this paper, we report a spiropyran-modified acrylate based monolith which is particularly sensitive to protonation in the MC form, producing a positively charged surface that converts to the unpolar SP form by exposure to white light. When the MC-H+ form is dominant, it produces a charged surface which enables a relatively high flow rate (up to 1.6 μl/min) to be generated under electroosmotic conditions. Upon exposure to white light, the concentration of MC-H+ decreases due to the photo-conversion to the uncharged SP form, with up to 20% reduction of the EOF. The process is reversible, and removal of...
Conserving the world’s cultural and natural heritage is considered a key contributor to achieving... more Conserving the world’s cultural and natural heritage is considered a key contributor to achieving the targets set out in the United Nation’s Sustainable Development Goals, yet how much attention do we pay to the methods we use to conserve and protect this heritage? With a specific focus on wooden objects of cultural heritage, this review discusses the current state-of-the-art in heritage conservation in terms of sustainability, sustainable alternatives to currently used consolidants, and new research directions that could lead to more sustainable consolidants in the future. Within each stage a thorough discussion of the synthesis mechanisms and/or extraction protocols, particularly for bio-based resources is provided, evaluating resource usage and environmental impact. This is intended to give the reader a better understanding of the overall sustainability of each different approach and better evaluate consolidant choices for a more sustainable approach. The challenges facing the de...
Enclosed is the raw data for the UV-Vis study that was presented in the manuscript, along with th... more Enclosed is the raw data for the UV-Vis study that was presented in the manuscript, along with the DLS data collected.
The removal of water from archaeological wooden objects for display or storage is of great import... more The removal of water from archaeological wooden objects for display or storage is of great importance to their long-term conservation. Any mechanical instability caused during drying can induce warping or cracking of the wood cells, leading to irreparable damage of the object. Drying of an object is commonly carried out in one of three ways: (i) air-drying with controlled temperature and relative humidity, (ii) drying-out of a non-aqueous solvent or (iii) freeze-drying. Recently, there has been great interest in the replacement of the standard, but limited, polyethylene glycol with biopolymers for wood conservation; however, their behaviour and action within the wood is not completely understood. Three polysaccharides—low-molar-mass (Mw) chitosan (Mw ca. 60,000 g/mol), medium-molar-mass alginate (Mw ca. 100,000 g/mol) and cellulose nanocrystals (CNCs)-are investigated in relation to their drying behaviour. The method of drying reveals a significant difference in the morphology of th...
A booming global population and the environmental impact of concrete and steel has forced constru... more A booming global population and the environmental impact of concrete and steel has forced construction engineers to expand their horizons in the search for new materials for sustainable housing. A promising solution is the use of fast-growing native woods for the construction of housing and shelter, particularly in developing countries and to quickly replace housing destroyed by natural disaster. In contrast to slower-growing species, such as wood is often of a lower construction grade and, therefore not suitable for use without further modification. Attempting to solve this issue has led to widespread research on the development of polymer-infused or -treated wood products, so-called wood polymer composites (WPCs). The extraordinary properties of WPCs have led to further research in the area of wood polymer nanocomposites (WPNCs), generally containing additional nanofillers to enhance strength. These composites provide a positive outlook not only for new wooden constructions but al...
The preservation of cultural heritage is of great importance worldwide and, as such, has been the... more The preservation of cultural heritage is of great importance worldwide and, as such, has been the focus of an increasing number of research projects in recent years. In spite of considerable efforts around the world, significant problems have arisen with the conservation of many shipwrecks. The most common issues facing conservators are structural instability upon drying and biological degradation stemming from the aquatic flora and fauna active around the excavation site. However, many important artefacts – such as the sixteenth century warship Mary Rose – also suffer from metal ion saturation from degraded bolts and fittings. In most cases Fe3+ is the greatest problem, which catalyses the production of sulfuric and oxalic acid in the waterlogged timbers, adding chemical degradation to the potential conservation issues. Moreover, the Fe3+ also feeds biological degradation by providing bacteria with an iron source for sustained growth. As such, multi-functional consolidants are grea...
A noninvasive method to assess the local monomer concentration within a wooden matrix, post monom... more A noninvasive method to assess the local monomer concentration within a wooden matrix, post monomer impregnation, by time-resolved diffuse optical spectroscopy is demonstrated. A data analysis technique for improving accuracy, which takes account of changes in the refractive index during the monomer uptake, has been employed. This technique can be potentially applied in the wood industry for the study of polymer composites as well as in cultural heritage science for noninvasively monitoring the penetration of chemical compounds used for consolidation or conservation purposes.
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Papers by Zarah Walsh-Korb