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Biomedical subjects

M N Jones

Publications and source records attributed to M N Jones.

At least 19 recordsLinked to original sources
PubMed2003

Calcium mobilisation and CCK secretion induced by modified fatty acids and latex microspheres reveal dual receptor mechanisms for lipid stimulation of STC-1 cells.

How fatty acids stimulate enteroendocrine cells to release cholecystokinin (CCK) is largely unknown. Recently, we proposed that the murine enteroendocrine cell line, STC-1, responds to insoluble fatty acid aggregates rather than fatty acid monomers in solution. This hypothesis led to two testable predictions. First, other insoluble particles of similar size but unrelated to fatty acid may be able to stimulate STC-1 cells in a similar fashion to dodecanoic acid and second, fatty acid sensing in STC-1 cells should be fairly insensitive to chemical modifications of the fatty acid as long as these modifications do not greatly alter the ability of the molecule to form insoluble aggregates. We used several analogues of dodecanoic acid and several varieties of latex microsphere (varying in size and surface charge) to see whether the predictions of our model hold. We found that while there was at least one latex microsphere that could induce CCK secretion and calcium mobilisation in STC-1 cells, there was a very poor correlation between the presence of insoluble aggregates and a cellular response. Instead the most important property, determining the potency of fatty acid analogues as stimulants of CCK secretion, was their amphipathicity. Removal of either the polar head or lipophilic tail completely abolished the ability of a given fatty acid analogue to stimulate STC-1 cells. These data suggested that while fatty acids can stimulate cells as aggregates, they may also be acting in monomeric form with the oil:water partitioning coefficient playing a crucial role. We finally resolved this issue with the observation that the sulfate ion greatly altered the response of STC-1 cells to monomeric dodecanoic acid. In the presence of sulfate, STC-1 cells will only respond to dodecanoic acid aggregates whereas when sulfate is replaced with chloride the cells clearly respond to dodecanoic acid monomers which are completely in solution. In summary, we propose that dodecanoic acid can stimulate STC-1 cells via two separate pathways one involving fatty acid monomers in solution and one involving fatty acid aggregates. Which pathway dominates depends on the presence of sulfate in the extracellular medium.

Animals↗
PubMed2002

Fatty acid signalling in a mouse enteroendocrine cell line involves fatty acid aggregates rather than free fatty acids.

Fatty acids induce cholecystokinin (CCK) secretion both in humans and from murine enteroendocrine cell lines. In both cases, only fatty acids above a critical acyl chain length (C(10)) are capable of inducing a response. Using the enteroendocrine cell line STC-1, the aim of this study was to determine whether this acyl chain length dependency is related to the fact that longer chain fatty acids are relatively insoluble in aqueous solutions and, if so, whether it is insoluble aggregates of fatty acids rather than free fatty acids which evoke CCK secretion. Solutions of fatty acids (chain length C(8)-C(14)), which were judged by filtration and Zeta sizer measurement to contain no fatty acid aggregates, never evoked CCK secretion from STC-1 cells. Filtering fatty acid solutions (of chain length C(10), C(12) and C(14)) through polytetrafluoroethylene (PTFE) filters (0.45 microm pore size) revealed a narrow concentration range for each acid over which the amount of fatty acid removed from the solution increased sharply due to the formation of fatty acid aggregates. Filtration experiments, in which suspensions of C(10), C(12) and C(14) fatty acids were passed through pore sizes of 0.2, 0.45 or 1.2 microm, suggested that STC-1 cells did not respond to fatty acid aggregates of greater than 1.2 microm, while at least 50 % of the CCK response was mediated by aggregates which were smaller than 0.45 microm. Fatty acids induce CCK secretion from STC-1 cells by elevating intracellular Ca(2+) concentration ([Ca(2+)](i)). We therefore measured the effects on [Ca(2+)](i) of filtered C(10), C(12) and C(14) fatty acids. In all cases, [Ca(2+)](i) responses were closely correlated with CCK secretion. Interestingly, while filtrates of fatty acid solutions evoked CCK secretion and elevated [Ca(2+)](i), freshly prepared solutions of fatty acids at the same concentration as the filtrates did not. This suggested that fatty acid aggregates were not in equilibrium with the solvent after filtration. The observation that the ability of C(10), C(12) and C(14) filtrates to elevate [Ca(2+)](i) decayed with time was consistent with this hypothesis. Furthermore, sonication of the filtrates abolished their ability to elevate [Ca(2+)](i). These data further suggest that it is a physical property of the fatty acid solution (the presence of insoluble fatty aggregates) which is responsible for the observed cellular responses. We conclude that Ca(2+) mobilisation and CCK secretion in STC-1 cells is driven by a signal transduction mechanism that senses insoluble fatty acid aggregates, rather than free fatty acids in solution.

Animals↗
PubMed2001

The molecular properties of humic substances isolated from a UK upland peat system: a temporal investigation.

The study concerns the possible changes in the molecular characteristics of humic materials isolated from the same source as a function of time. A great deal of data has been reported concerning the contrast in molecular characteristics of humic substances isolated from different environments. This has primarily been an attempt to identify source-specific molecular characteristics. However, data presented in this paper suggests that humic substances isolated from a single catchment have significant changes in molecular characteristics over time. Two naturally occurring peat pools (X and Y) situated upon a small organic catchment on Great Dun Fell, Cumbria, UK were sampled monthly between November 1994 and November 1996. Dissolved organic matter (DOM) from the pool water samples was fractionated using macroporous nonionic resins (XAD8 and 4), and the humic, fulvic and hydrophilic acids were collected. These fractions were analysed for elemental composition (C, H and N), weight average molecular weight, functional group content and adsorption (340 nm) of a 1 g l(-1) solution measured in a 1-cm spectrophotometer cell. The molecular characteristics were compared to those of natural DOM described by Scott et al. (1998). Scott et al. reported that drought conditions and seasonal climatic changes could have appreciable effects upon molecular characteristics of natural DOM. Results showed that the atomic H/C ratio of the humic substances increased immediately after strong drought conditions experienced in the summer of 1995. This change was temporary with atomic H/C ratio decreasing gradually over the following months. A similar decrease was observed in the carboxyl group content of the isolated compounds. The data set suggested that atomic H/C ratio in the fulvic and hydrophilic fractions exhibited seasonal characteristics of higher ratios during the late summer/early autumn months. This was not observed in the humic fraction. Humic acids exhibited a seasonal pattern of higher weight average molecular weight during the summer months. These trends were explained in terms of summer production of DOM in the catchment soils, their sequestering in the soil due to limited soil water movement during the summer months and their relative ease of dissolution when rainfall and soil water movement increased during the late summer/early autumn period. The results were found to support seasonal and long-term patterns observed in natural DOM as reported by Scott et al. (1998).

Benzopyrans↗
PubMed2000

The biodegradation of surfactants in the environment.

The possible contamination of the environment by surfactants arising from the widespread use of detergent formulations has been reviewed. Two of the major surfactants in current use are the linear alkylbenzene sulphonates (LAS) and the alkyl phenol ethoxylates (APE). These pass into the sewage treatment plants where they are partially aerobically degraded and partially adsorbed to sewage sludge that is applied to land. The biodegradation of these and a range of other surfactants both in wastewater treatment plants and after discharge into natural waters and application to land resulting in sewage sludge amended soils has been considered. Although the application of sewage sludge to soil can result in surfactant levels generally in a range 0 to 3 mg kg(-1), in the aerobic soil environment a surfactant can undergo further degradation so that the risk to the biota in soil is very small, with margins of safety that are often at least 100. In the case of APE, while the surfactants themselves show little toxicity their breakdown products, principally nonyl and octyl phenols adsorb readily to suspended solids and are known to exhibit oestrogen-like properties, possibly linked to a decreasing male sperm count and carcinogenic effects. While there is little serious risk to the environment from commonly used anionic surfactants, cationic surfactants are known to be much more toxic and at present there is a lack of data on the degradation of cationics and their fate in the environment.

Biodegradation, Environmental↗
PubMed2000

Effect of grafted polyethylene glycol (PEG) on the size, encapsulation efficiency and permeability of vesicles.

Liposomes have been prepared by the vesicle extrusion method (VETs) from mixtures of dipalmitoylphosphatidylcholine (DPPC), phosphatidylinositol (PI) and dipalmitoylphosphatidylethanolamine with covalently linked poly(ethylene glycol) molecular mass 5000 and 2000 (DPPE-PEG 5000 and DPPE-PEG 2000) covering a range of 0-7.5 mole%. The encapsulation of D-glucose has been studied and found to be markedly dependent on the mole% DPPE-PEG. The permeability of the liposomes to D-glucose has been measured both as a function of temperature and liposome composition. The permeability coefficients for D-glucose increase with mole% DPPE-PEG 5000 and with temperature over the range 25-50 degrees C. The activation energies for glucose permeability range from 90 to 23 kJ mol(-1). The decrease in activation energy with increasing temperature is attributed to an increasing number of bilayer defects as the liposome content of PEG-grafted lipid is increased. The dependence of D-glucose encapsulation as a function of PEG-grafted lipid content is discussed in terms of the conformation of the PEG molecules on the inner surface of the bilayer. For liposomes containing DPPE-PEG 5000 the relative percentage encapsulation of glucose, assuming that the PEG surface layer excludes glucose, is comparable to that predicted from the mushroom and brush conformational models.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed2000

The use of immunoliposomes for specific delivery of antimicrobial agents to oral bacteria immobilized on polystyrene.

Antibacterial immunoliposomes have been prepared using covalently bound antibody, raised to the cell surface of the bacterium Streptococcus oralis (S. oralis), and incorporating the bactericides chlorhexidine and Triclosan. A regrowth assay, in which the ability of a bacterial biofilm immobilised on polystyrene to grow after exposure to a test solution, was undertaken to study the action of the antibacterial immunoliposomes. The antibacterial anti-oralis immunoliposomes show enhanced growth inhibition of S. oralis, compared to free bactericide, using low bactericide concentrations. For short exposure times to the biofilms, antibacterial anti-oralis immunoliposomes can show several times enhanced growth inhibition of S. oralis compared to free bactericide. Antibacterial anti-oralis immunoliposomes inhibit the growth of S. oralis more than that of other oral bacteria. The extent of growth inhibition by antibacterial anti-oralis immunoliposomes is linearly related to the number of immunoliposomes targeted to the biofilm surface.

Anti-Infective Agents, Local↗
PubMed1999

Hydrogen peroxide production from reactive liposomes encapsulating enzymes.

Reactive cationic and anionic liposomes have been prepared from mixtures of dimyristoylphosphatidylcholine (DMPC) and cholesterol incorporating dimethyldioctadecylammonium bromide and DMPC incorporating phosphatidylinositol, respectively. The liposomes were prepared by the vesicle extrusion technique and had the enzymes glucose oxidase (GO) encapsulated in combination with horseradish peroxidase (HRP) or lactoperoxidase (LPO). The generation of hydrogen peroxide from the liposomes in response to externally added D-glucose substrate was monitored using a Rank electrode system polarised to +650 mV, relative to a standard silver-silver chloride electrode. The effects of encapsulated enzyme concentration, enzyme combinations (GO+HRP, GO+LPO), substrate concentration, electron donor and temperature on the production of hydrogen peroxide have been investigated. The electrode signal (peroxide production) was found to increase linearly with GO incorporation, was reduced on addition of HRP and an electron donor (o-dianisidine) and showed a maximum at the lipid chain-melting temperature from the anionic liposomes containing no cholesterol. To aid interpretation of the results, the permeability of the non-reactive substrate (methyl glucoside) across the bilayer membranes was measured. It was found that the encapsulation of the enzymes effected the permeability coefficients of methyl glucoside, increasing them in the case of anionic liposomes and decreasing them in the case of cationic liposomes. These observations are discussed in terms of enzyme bilayer interactions.

Cholesterol↗
PubMed1999

Surfactants in membrane solubilisation.

An understanding of the action of many drugs requires a knowledge of how the drug reaches the site of action in a cell. A detailed knowledge of the structure and function of cell membranes is often required to understand the transport of drugs across the plasma membrane. To obtain this information proteins must be isolated. The isolation and characterisation of cell membrane proteins usually requires the solubilisation of the membrane and a method of separation of the various membrane proteins and glycoproteins. The starting point for such an investigation is the choice of a suitable surfactant (detergent) to solubilise the membrane. This review considers the range of surfactants that are available for membrane solubilisation, how surfactants interact with membranes, the part they play in the separation of integral membrane proteins and in the reconstitution of membrane proteins for functional studies. The solubilisation of specific membrane proteins and glycoproteins including the human erythrocyte anion transporter, mitochondrial porin, sarcoplasmic reticulum Ca(2+)-ATPase, the ATPase-active multidrug transporter P-glycoprotein, bacteriorhodopsin and rhodopsin are also discussed.

Humans↗
PubMed1999

Fatty acid chain length determines cholecystokinin secretion and effect on human gastric motility.

BACKGROUND & AIMS: Fatty acids induce cholecystokinin (CCK) secretion and modify gastric motility, but the chain length requirements for these effects are not known. Nor is it clear whether the effects of fatty acids on gastric motility in humans are CCK mediated or directly exerted. The aim of this study was to determine the role of fatty acyl chain length in CCK secretion and in influencing gastric motility. METHODS: Fatty acids were infused into the upper gut in healthy volunteers; plasma CCK was determined by radioimmunoassay. Effects of fatty acids on antral contractility were determined by percutaneous ultrasonography; effects on proximal gastric tone were studied during fundal distention. RESULTS: Plasma CCK concentration was consistently and similarly elevated by fatty acids with a chain of 12 carbon atoms or longer, whereas those of 11 or fewer carbon atoms failed to increase plasma CCK. A 12-carbon but not a 10-carbon-long chain fatty acid reduced antral contractile amplitude, an effect that was abolished by loxiglumide (a specific CCK-A receptor antagonist). The 12-carbon fatty acid also reduced proximal gastric tone more than the 10-carbon fatty acid. CONCLUSIONS: A highly specific, chain length-sensitive fatty acid recognition system exists in the proximal gut mediating CCK secretion and gastric motility. An additional, probably CCK-independent, effect of fatty acid also regulates proximal gastric tone.

Adolescent↗
PubMed1998

Phospholipid free thin liquid films with grafted poly(ethylene glycol)-2000: formation, interaction forces and phase states.

Free thin liquid films (foam films) formed from aqueous dispersions of dimyristoylphosphatidylcholine (DMPC) and dipalmitoylphosphatidylethanolamine with covalently bound poly-(ethylene glycol) of molecular weight 2000 (DPPE-PEG-2000) were studied by the thin liquid film microinterferometric technique of Scheludko and Exerowa in the temperature range 14-36 degrees C. The surface tension kinetics of the dispersions were studied in order to ensure equilibration of the foam films. These measurements showed that the rate of surface coverage depends slightly on the temperature and does not reach equilibrium values within reasonable time intervals for the dispersions containing only one amphiphile (DPPE-PEG-2000). The destruction of the vesicles at the air/(aqueous dispersion) interface was much faster for the dispersions containing DMPC/DPPE-PEG-2000 mixtures above 23 degrees C, the temperature of the chain-melting phase transition of the main lipid component (DMPC). The dependence of the equilibrium thickness of the foam films on the electrolyte concentration was measured for 1 and 9 mol% DPPE-PEG-2000 at 28 degrees C in the range 10-3 to 0.5 M NaCl. These results indicate that at the low electrolyte concentrations the electrostatic and van der Waals interactions are dominant similar to the foam films stabilized with DMPC alone. At the high electrolyte concentrations the steric repulsion of the PEG layers becomes dominant. The temperature-composition dependence of the bilayer thickness was measured for the foam bilayers at 0.14 M NaCl. The data for the foam bilayer thickness and the comparison with the phase diagrams of PC/PE-PEG dispersions, show that the DMPC/DPPE-PEG-2000 foam bilayers are able to exist in two phase states characterised by different conformations (mushroom and brush) of the grafted polymer.

Adsorption↗
PubMed1998

The specificity and affinity of immunoliposome targeting to oral bacteria.

Immunoliposomes have been prepared using antibodies raised to an antigenic determinant on the cell surface of the oral bacterium Streptococcus oralis (S. oralis) in an investigation of their potential to reduce dental plaque. The N-succinimidyl-S-acetylthioacetate (SATA) derivative of the antibodies were conjugated through the reactive m-maleimidobenzoyl-N-hydroxysuccinimide (MBS) derivative of dipalmitoyl-phosphatidylethanolamine (DPPE) incorporated into liposomes. The degree of antibody conjugation to the liposomes was controlled by the percentage of DPPEMBS incorporated into the liposomes. The chemical modification of the antibodies did not affect the ability of the antibodies to bind to a S. oralis biofilm. However, the affinity of the immunoliposomes for S. oralis was much lower than that of the free antibody. The anti-oralis antibodies were highly specific for S. oralis. The anti-oralis immunoliposomes showed the greatest affinity for S. oralis, when targeted to a range of different oral bacterial biofilms. The immunoliposome targeting affinity for S. oralis was largely unaffected by the number of antibodies conjugated to the liposomal surface or by the net charge of the liposomal lipid bilayer. The immunoliposomes showed a greater affinity for S. oralis than 'naked' (bearing no antibody) liposomes. However, positively charged liposomes, incorporating stearylamine, adsorbed to S. oralis with greater affinities than the immunoliposomes. The immunoliposomes appeared to be physically stable over a period of 18 months, as judged by particle-size measurements.

Anti-Bacterial Agents↗
PubMed1997

Characterization of apical potassium channels induced in rat distal colon during potassium adaptation.

1. Chronic dietary K+ loading stimulates an active K+ secretory process in rat distal colon, which involves an increase in the macroscopic apical K+ conductance of surface epithelial cells. In the present study, the abundance and characteristics of K+ channels constituting this enhanced apical K+ conductance were evaluated using patch clamp recording techniques. 2. In isolated non-polarized surface cells, K+ channels were seen in 9 of 90 (10%) cell-attached patches in cells from control animals, and in 247 of 437 (57%) cell-attached patches in cells from K(+)-loaded animals, with a significant (P < 0.001) shift in distribution density. Similarly, recordings from cell-attached patches of the apical membrane of surface cells surrounding the openings of distal colonic crypts revealed identical K+ channels in 1 of 11 (9%) patches in control animals, and in 9 of 13 (69%) patches in K(+)-loaded animals. 3. In isolated surface cells and surface cells in situ, K+ channels had mean slope conductances of 209 +/- 6 and 233 +/- 14 pS, respectively, when inside-out patches were bathed symmetrically in K2SO4 solution. The channels were sensitive to 'cytosolic' Ca2+ concentration, were voltage sensitive at 'cytosolic' Ca2+ concentrations encountered in colonic epithelial cells, and were inhibited by 1 mM quinidine, 20 mM TEA or 5 mM Ba2+ ions. 4. The data show that dietary K+ loading increases the abundance of Ca(2+)- and voltage-sensitive large-conductance K+ channels in the apical membrane of surface cells in rat distal colon. These channels constitute the enhanced macroscopic apical K+ conductance previously identified in these cells, and are likely to play a critical role in the active K+ secretory process that typifies this model of colonic K+ adaptation.

Adaptation, Physiological↗
PubMed1997

Reactive liposomes encapsulating a glucose oxidase-peroxidase system with antibacterial activity.

Liposomes were prepared from phospholipid mixtures of dipalmitoylphosphatidylcholine (DPPC) and phosphatidylinositol (PI), encapsulating the enzymes glucose oxidase (GO) and GO in combination with horse radish peroxidase (HRP) by both extrusion (VET) and reverse-phase evaporation (REV). The optimum level of PI in DPPC/PI liposomes for targeting to biofilms of the oral bacterium Streptococcus gordonii has been established. The liposomes were characterised in terms of the content and activity of the encapsulated enzymes. The antibacterial activity of these 'reactive' liposomes arising from hydrogen peroxide and oxyacids in the presence of the substrates glucose and iodide ions, after targeting to the biofilms, were measured both as a function of liposome-biofilm incubation time and incubation time with the substrates. Bacterial inhibition increases with both liposome-biofilm and substrate-biofilm incubation time and with the extent of enzyme encapsulation. The reactive liposomes also display antibacterial activity in the presence of saliva. The reactive liposomes have potential value in the context of oral hygiene.

Anti-Bacterial Agents↗
PubMed1997

Selectivity in the complexation of actinides by humic substances.

The interactions of a range of actinide elements (Th, U, Np, Pu, Am) with humic substances from the Needle's Eye natural analogue site were studied by gel permeation chromatography. Bulk humic substances were isolated by ammonia extraction, followed by dialysis against distilled water and freeze-drying. The gel permeation results suggest that Needle's Eye humic substances can be fractionated into three incompletely resolved fractions with average molecular weights determined by analytical ultracentrifugation around 49 000 for Fraction 1, around 14 700 for Fraction 2 and around 8000 for Fraction 3. Although there are significant differences between the organic matter elution patterns in individual gel permeation experiments, presumably due to differences in column packing, these are much smaller than the differences between metal ions. The uranium that is naturally present in these humic substances is largely bound in the late-eluting fraction. Spikes of the early actinides, including Np and Pu in controlled valency states, have been added to the humic substances, and gel permeation of the spiked humic substances shows that the three humic fractions vary greatly in their effectiveness and selectivity as ligands for early actinides.

Journal Article↗
PubMed1997

The interaction of phospholipid liposomes with bacteria and their use in the delivery of bactericides.

Liposomes have been prepared from dipalmitoylphosphatidylcholine (DPPC) incorporating the cationic lipids stearylamine (SA), dimethyldioctadecylammonium bromide (DDAB) and dimethylaminoethane carbamoyl cholesterol (DCchol) and the anionic lipids dipalmitoylphosphatidylglycerol (DPPG) and phosphatidylinositol (PI). Their adsorption to biofilms of skin-associated bacteria (Staphylococcus epidermidis and Proteus vulgaris) and oral bacteria (Streptococcus mutans and sanguis) has been investigated as a function of mole % cationic and anionic lipid. Targeting (adsorption) was most effective for the systems DPPC-chol-SA, DPPC-DPPG and DPPC-PI liposomes to S. epidermidis. The effect of extracellular mucopolysaccharide on targeting was investigated for S. epidermidis biofilms. It was found that targeting increased with the level of extracellular mucopolysaccharide for all liposome compositions studied. The delivery of the oil-soluble bactericide Triclosan and the water soluble bactericide chlorhexidine was studied for a number of liposomal compositions. Superior delivery of both bactericides relative to the free bactericide occurred for DPPC-chol-SA liposomes and for Triclosan delivery by DPPC-DPPG and DPPC-PI liposomes targeted to S. epidermidis at low bactericide concentrations. DPPC-chol-SA liposomes were also effective for delivery of Triclosan to S. sanguis biofilms. Double labelling experiments using [14C]-chlorhexidine and [3H]-DPPC suggested that there was exchange between adsorbed liposomes which had delivered bactericide to the biofilm and those in the bulk solution implying a diffusion mechanism for bactericide delivery.

Anti-Bacterial Agents↗
PubMed1996

Effect of grafted PEG-2000 on the size and permeability of vesicles.

The permeability of PEG-derivatized vesicles produced by the extrusion technique (VETs) to encapsulated D-glucose has been studied. Vesicles were prepared from mixtures of dipalmitoylphosphatidylcholine (DPPC), phosphatidylinositol (PI) and dipalmitoylphosphatidylethanolamine with covalently attached poly(ethylene glycol) of molecular weight 2000 (DPPE-PEG2000). The occurrence of an irreversible temperature-induced size transition of the PEG-derivatized VETs was detected close to the temperature of the main phase transition of the predominant phospholipid component by photon correlation spectroscopy. The permeability of the vesicles towards radioactive D-glucose was studied by a method similar to the one proposed by Johnson and Bangham at 25, 37 and 50 degrees C for VETs with DPPE-PEG content from 0 to 9 mol%. A complex effect of the PEG-coverage was found with a maximum leakage in the range of the transition of the polymer from the mushroom to the brush conformation.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1996

The interaction of cationic liposomes with the skin-associated bacterium Staphylococcus epidermidis: effects of ionic strength and temperature.

Cationic liposomes have been prepared from dipalmitoylphosphatidylcholine (DPPC), cholesterol (Chol) and stearylamine (SA). These phospholipid vesicles were exposed to adsorbed biofilms of the skin-associated bacteria Staphylococcus epidermidis, to which they showed a strong affinity. The interaction (as assessed by the apparent monolayer coverage of the biofilms by liposomes) was described in terms of a Langmuir adsorption isotherm which enabled determination of the maximum theoretical coverage of the bacterial surface and association/dissociation constants. The interaction was shown to be dependent on the ionic strength of the surrounding medium; on increasing the ionic strength the biofilm-vesicle dissociation constant decreased. This suggested that the adsorption was mediated by electrostatic effects. The adsorption of the vesicles was examined at various temperatures, enabling determination of thermodynamic parameters for the interaction. The adsorbed state of the liposomes was energetically favoured and the interaction was enthalpy driven. The Gibbs energies of adsorption were in a range from -15 to -19 kJ mol-1 and the enthalpies of adsorption from -26 to -22 kJ mol-1. Studies using cell populations of different hydrophobicity showed that the hydrophobic character of the bacterial cells also had an effect on the adsorption of the vesicles to the biofilm.

Adsorption↗