Pascale Schwinte - Academia.edu (original) (raw)

Papers by Pascale Schwinte

Research paper thumbnail of Integrating Microtissues in Nanofiber Scaffolds for Regenerative Nanomedicine

Research paper thumbnail of Active Nanomaterials to Meet the Challenge of Dental Pulp Regeneration

Research paper thumbnail of Build-up of Polypeptide Multilayer Coatings with Anti-Inflammatory Properties Based on the Embedding of Piroxicam–Cyclodextrin Complexes

Advanced Functional Materials, 2004

... Px into the multilayers, we used a charged cyclodextrin molecule, 6A-carboxymethylthio-β-cycl... more ... Px into the multilayers, we used a charged cyclodextrin molecule, 6A-carboxymethylthio-β-cyclo-dextrin (cCD, see Scheme 1b), to form Px±cyclodextrin com-plexes (cCD±Px). ... The com-plexes were then embedded in poly(L-glutamic acid) (PGA)/ poly(L-lysine) (PLL) multilayers ...

Research paper thumbnail of Active implant combining human stem cell microtissues and growth factors for bone-regenerative nanomedicine

Nanomedicine (London, England), 2015

Mesenchymal stem cells (MSCs) from adult bone marrow provide an exciting and promising stem cell ... more Mesenchymal stem cells (MSCs) from adult bone marrow provide an exciting and promising stem cell population for the repair of bone in skeletal diseases. Here, we describe a new generation of collagen nanofiber implant functionalized with growth factor BMP-7 nanoreservoirs and equipped with human MSC microtissues (MTs) for regenerative nanomedicine. By using a 3D nanofibrous collagen membrane and by adding MTs rather than single cells, we optimize the microenvironment for cell colonization, differentiation and growth. Furthermore, in this study, we have shown that by combining BMP-7 with these MSC MTs in this double 3D environment, we further accelerate bone growth in vivo. The strategy described here should enhance the efficiency of therapeutic implants compared with current simplistic approaches used in the clinic today based on collagen implants soaked in bone morphogenic proteins.

Research paper thumbnail of Active Nanomaterials to Meet the Challenge of Dental Pulp Regeneration

Research paper thumbnail of Synthesis of Selectively13C-Labelled Bilin Compounds

Eur J Org Chem, 2007

A series of open-chain tetrapyrroles, each carrying one or more 13 C-labels in its three ring-bri... more A series of open-chain tetrapyrroles, each carrying one or more 13 C-labels in its three ring-bridging methine groups, were synthesized. These compounds - [5-, [10-, and [15-13 C]phycocyanobilins (PCB), [10-13 C]-phytochromobilin, and [10,15-13 C 2 ]-PCB -were each obtained by a convergent route, starting with the four pyrrole building blocks, with the initial formation of the left and the right halves of the tetrapyrrole separately, followed by a final condensation of the two dipyrrole units to yield the target bilin compound. The

Research paper thumbnail of Integrating Microtissues in Nanofiber Scaffolds for Regenerative Nanomedicine

Research paper thumbnail of Double compartmented and hybrid implant outfitted with well-organized 3D stem cells for osteochondral regenerative nanomedicine

Nanomedicine (London, England), 2015

Articular cartilage repair remains challenging, because most clinical failures are due to the lac... more Articular cartilage repair remains challenging, because most clinical failures are due to the lack of subchondral bone regeneration. We report an innovative approach improving cartilage repair by regenerating a robust subchondral bone, supporting articular cartilage. We developed a compartmented living implant containing triple-3D structure: stem cells as microtissues for embryonic endochondral development mimic, nanofibrous collagen to enhance mineralization for subchondral bone and alginate hydrogel for cartilage regeneration. This system mimics the natural gradient of the osteochondral unit, using only one kind of stem cell, targeting their ability to express specific bone or cartilage proteins. Mineralization gradient of articular cartilage and the natural 'glue' between subchondral bone and cartilage were reproduced in vitro.

Research paper thumbnail of Ditopic binding of nucleotides by heptakis(6-hydroxyethylamino-6-deoxy)-β-cyclodextrin

Journal of The Chemical Society-perkin Transactions 2, 1998

The potential of heptakis (6-hydroxyethylamino-6-deoxy)-β-cyclodextrin (1) as a ditopic receptor ... more The potential of heptakis (6-hydroxyethylamino-6-deoxy)-β-cyclodextrin (1) as a ditopic receptor capable of electrostatic interaction and hydrogen bonding by its amino side-chains, together with inclusion in its hydrophobic cavity, has been assessed for nucleotides as ...

Research paper thumbnail of A persubstituted cationic beta-cyclodextrin for chiral separations

Analytical chemistry, 1997

The applications of a novel polycationic derivative of beta-cyclodextrin (beta-CD), heptakis(6-hy... more The applications of a novel polycationic derivative of beta-cyclodextrin (beta-CD), heptakis(6-hydroxyethylamino-6-deoxy-beta-cyclodextrin) (beta-CD-EA), as a chiral host--guest additive for the enantioseparation of various classes of chiral anionic analytes are presented. The cationic beta-CD described in this paper is persubstituted with seven ethanolamine side arms at the primary rim of each cyclodextrin (CD) molecule. It is found that the electrophoretic mobility of beta-CD-EA can be adjusted to influence the chiral selectivity by changing the pH of the background electrolyte. Most of the observed CD capillary zone electrophoresis (CZE) separations of anionic drugs and herbicides were accomplished in the pH range of 4.0-7.0 with a reverse polarity configuration. At pH 5.0, enantioseparation of a mixture of three structurally related antiinflammatory agents (fenoprofen, flurbiprofen, and ibuprofen) was possible in about 30 min. However, other chiral acids, such as a series of phe...

Research paper thumbnail of Cyclodextrin as a Template for Molecular Assembly: Formation of Heterodimers Between a Polyamino- and a Polysulfonato-β-Cyclodextrin

ABSTRACT A poly(hydroxyethylamino)- and a poly(sulfonatophenyloxy)-ß-cyclodextrin derivative, bea... more ABSTRACT A poly(hydroxyethylamino)- and a poly(sulfonatophenyloxy)-ß-cyclodextrin derivative, bearing opposite ionic charges, have been shown by potentiometric titration to form stable pH-dependent heterodimers with each other in water. The formation constants of these dimers show that a very stable assembly is formed between the fully deprotonated sulfonato derivative and the fully protonated amino derivative (log Ka = 8.5), which constitutes the assembly of multiple extended atomic groupings on cyclodextrin as template.

Research paper thumbnail of Amphiphilic 6-S-alkyl-6-thiocyclodextrins: unimolecular micellar and reverse micellar behaviour

Journal of the Chemical Society, Perkin Transactions 2, 1998

ABSTRACT Micellar behaviour of the amphiphilic 6-S-alkyl-6-thiocyclomaltooligosaccharid (2) in ch... more ABSTRACT Micellar behaviour of the amphiphilic 6-S-alkyl-6-thiocyclomaltooligosaccharid (2) in chloroform has been measured by use of the fluorescent probe 8-anilinonaphthalene-1-sulfonate (ANS) as guest molecule, as well as by water-chloroform interfacial tension measurements. At low concentrations the amphiphiles show behaviour consistent with their being oligomers of monosaccharide amphiphiles, or `unimolecular micelles'. Thus, with ANS, 1:1 complexes are formed for which the association constants are in proportion to the length of the chains. At higher concentrations, the long-chained (C-16, C-18) alkylthioeyclodextrins form inverted micellar aggregates. The NMR shift changes associated with inclusion of 1-naphthol indicate that even in these aggregates, the carbohydrate cavity plays a part in complexation, while the hydrophobic chains act as extensions of the more hydrophobic primary-hydroxy side of the cavity.

Research paper thumbnail of Stabilizing Effects of Various Polyelectrolyte Multilayer Films on the Structure of Adsorbed/Embedded Fibrinogen Molecules:  An ATR−FTIR Study †

The Journal of Physical Chemistry B, 2001

The structural changes in fibrinogen as a consequence of its adsorption onto the surface of or it... more The structural changes in fibrinogen as a consequence of its adsorption onto the surface of or its embedding into the interior of poly(allylamine hydrochloride) (PAH) or poly(styrenesulfonate) (PSS) multilayers are investigated by means of attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy. It is found that both adsorption and embedding preserve the secondary structure of the fibrinogen molecules. Furthermore, the interactions of the polyelectrolytes with the protein molecules prevent their aggregation, especially in the embedded state, at room temperature. Thus, it seems that the structure and the biological activity of proteins adsorbed on or embedded in polyelectrolyte multilayers could largely be preserved, which opens up great perspectives in the design of new bioactive surfaces. The nature and the extent of the polyelectrolyte-protein interactions are further studied via analysis of the thermotropic responses of the different architectures. It is found that both PAH-and PSS-terminated polyelectrolyte multilayers can elevate the onset temperature of the structural changes in adsorbed/embedded fibrinogen molecules by about 5°C as compared with that for fibrinogen in solution. These polyelectrolytes also broaden the thermally induced structural transitions in the adsorbed/embedded fibrinogen molecules. The magnitude of these thermally induced structural changes is polyelectrolyte-and architecture-dependent. Whereas multilayer PAH-fibrinogen and multilayer PSS-fibrinogen constructions exhibit roughly the same large-scale thermally induced structural changes, in all architectures where fibrinogen is embedded the scale of these structural changes is restricted. The restriction becomes stronger as the presence of PSS at the polyelectrolyte-fibrinogen interfaces increases (PAH-fib-PAH < PAH-fib-PSS ≈ PSS-fib-PAH < PSS-fib-PSS). In the PSS-fib-PSS arrangement, the secondary structure of fibrinogen as determined from its infrared spectrum changes only slightly up to 90°C. The underlying processes of the thermally induced structural changes is, in addition, different for fibrinogen molecules adsorbed onto or embedded into PAH-terminated polyelectrolyte multilayers. A tentative model based on "encapsulation" of the embedded protein by the polyelectrolytes is proposed to explain the observed features. † Part of the special issue "Howard Reiss Festschrift".

Research paper thumbnail of Ditopic binding of nucleotides by heptakis(6-hydroxyethylamino-6-deoxy)-β-cyclodextrin

Journal of the Chemical Society, Perkin Transactions 2, 1998

The potential of heptakis (6-hydroxyethylamino-6-deoxy)-β-cyclodextrin (1) as a ditopic receptor ... more The potential of heptakis (6-hydroxyethylamino-6-deoxy)-β-cyclodextrin (1) as a ditopic receptor capable of electrostatic interaction and hydrogen bonding by its amino side-chains, together with inclusion in its hydrophobic cavity, has been assessed for nucleotides as ...

Research paper thumbnail of Complexation of Pr3+, Eu3+, Yb3+ and Th4+ ions by calixarene carboxylates

Journal of the Chemical Society, Dalton Transactions, 1997

J. Chem. Soc., Dalton Trans., 1997, Pages 329–334 ... Complexation of Pr3+, Eu3+, Yb3+ and Th4+ i... more J. Chem. Soc., Dalton Trans., 1997, Pages 329–334 ... Complexation of Pr3+, Eu3+, Yb3+ and Th4+ ions by calixarene carboxylates* ... Françoise Arnaud-Neu,a Suzane Cremin,b Steve Harris,c M. Anthony McKervey,b Marie-José Schwing-Weill,a Pascale Schwintéa and ...

Research paper thumbnail of A living thick nanofibrous implant bifunctionalized with active growth factor and stem cells for bone regeneration

International Journal of Nanomedicine, 2015

Research paper thumbnail of Amphiphilic Cyclodextrin Complexation of Clofazimine

Journal of Inclusion Phenomena, 2003

ABSTRACT The cyclodextrin amphiphilesheptakis[6-(1&#39;-sulfonato-3&#39;-propyl)-6-thio-2... more ABSTRACT The cyclodextrin amphiphilesheptakis[6-(1&#39;-sulfonato-3&#39;-propyl)-6-thio-2,3-di-O-acetyl]--cyclodextrin,heptakis[6-(6&#39; -sulfonato-2&#39;-benzimidazolyl)-6-thio-2,3-di-O-acetyl]--cyclodextrin, and heptakis[6-(-D-glucosyl)-6-thio-2,3-di-O-acetyl]--cyclodextrin have been shown to form aggregates in water by fluorescencemeasurements on the binding of 2-anilinonaphthalene, and by laserlight-scattering measurements. Estimates of aggregation number have been obtained.These aggregates successfully incorporate clofazimine, a lipophilic heterocyclic drug,and increase its water solubility by a factor of 30 to 50.

Research paper thumbnail of Selective alkali-metal cation complexation by chemically modified calixarenes. Part 4. Effect of substituent variation on the Na+/K+ selectivity in the ester series and X-ray crystal structure of the trifluoroethyl ester

Journal of the Chemical Society, Perkin Transactions 2, 1992

ABSTRACT The cation complexing abilities of a series of p-tert-butylcalix[4]arenes bearing ligati... more ABSTRACT The cation complexing abilities of a series of p-tert-butylcalix[4]arenes bearing ligating ester groups in the cone conformation have been assessed by stability constant measurements in methanol and extraction studies from water into dichloromethane. The cations studied were Na+ and K+ and variations in the ester function (CO2R) included R = methyl, ethyl, n-butyl, tert-butyl, benzyl, phenyl, phenacyl, methoxyethyl, trifluoroethyl, methylthioethyl and prop-2-ynyl. The effect of replacing one or two ester functions in the tetraethyl ester by methyl ester, carboxylic acid, ketone and amide functions was also studied. Selectivities for Na+ relative to K+ in stability constants range from 2 to 2500, the phenacyl derivative having the highest selectivity. X-Ray diffraction analysis was used to probe the conformation of the trifluoroethyl ester 11. Crystals of 11 are monoclinic, space group P21/n, in a cell of dimensions a= 13.987(2), b= 16.194(3), c= 27.630(5)Å; β= 98.70(1)°; R= 0.077 for 3172 observed data. The compound possesses a distorted cone conformation.

Research paper thumbnail of Complexation Mechanism of Bovine Serum Albumin and Poly(allylamine hydrochloride)

The Journal of Physical Chemistry B, 2002

ABSTRACT The mechanism of aggregation of bovine serum albumin (BSA) by poly(allylamine) hydrochlo... more ABSTRACT The mechanism of aggregation of bovine serum albumin (BSA) by poly(allylamine) hydrochloride (PAH) is investigated as a function of the mixing ratio r defined as the ratio of the number of BSA molecules and PAH chains present in the solution, under pH conditions of strong binding between the two partners. It is found that as r increases the turbidity first increases, passes through a maximum at a value rmax before decreasing again. For small and large values of r, one forms small aggregates in the 10 nanometer size range, whereas at rmax, the size of the aggregates becomes of the order of micrometers. The structure of the aggregates appears to be independent of the history of the systems but depends only on the value of r despite the strong BSA/PAH binding. The desaggregation of the large aggregates formed at rmax by the addition of BSA or PAH is shown to be an isenthalpic process and is thus entirely entropically driven. Moreover, we prove that rmax corresponds to the state of the system where both the PAH chains and the BSA molecules interact one with each other, both with their maximum number of interaction points per molecule. This explains the independence of rmax on the BSA or PAH concentration in the solution and why it varies linearly with the molecular weight of the polyelectrolyte. Moreover, we show that at rmax, all the BSA and PAH molecules present in the solution are involved in the aggregates. At small (respectively large) values of r, the aggregates appear positively (respectively negatively) charged, corresponding to a charge excess at the surface of the aggregates. Finally, it is found that the protein/polyelectrolyte interaction is endothermic, indicating that the BSA/PAH binding must thus be entropically driven. The binding enthalpy of BSA molecules with PAH chains for r &lt; rmax is of the order of 400 kJ·mol-1 of BSA molecules for solutions containing less than 0.1M of NaCl. The effect of the salt concentration of the solution on the binding process is also briefly discussed.

Research paper thumbnail of Dynamical Behavior of Human Serum Albumin Adsorbed on or Embedded in Polyelectrolyte Multilayers

The Journal of Physical Chemistry B, 2002

We investigate the lateral diffusion of Human Serum Albumin-Fluorescein Isothiocyanate (HSA) adso... more We investigate the lateral diffusion of Human Serum Albumin-Fluorescein Isothiocyanate (HSA) adsorbed "on" or embedded "in" poly(sodium 4-styrenesulfonate)/poly(allylamine hydrochloride) (PSS/PAH) multilayers. Special attention is brought to the evolution of the diffusion coefficient with the surface HSA concentration. We find that while on PSS terminating films the diffusion coefficient of adsorbed HSA is independent of the protein surface concentration in the explored range, it decreases strongly with the surface concentration when HSA is adsorbed on PAH ending films. On both films, the mobile fraction of adsorbed protein molecules decreases when the surface concentration increases. At low surface coverage, up to 90% of the adsorbed protein molecules are mobile both on PSS and PAH terminating films. The decrease of the mobile fraction with the HSA surface concentration is more pronounced on PSS than on PAH reaching, respectively, 50% and 70% of mobile HSA molecules at high surface coverage. This behavior is typical for protein aggregation. Infrared spectroscopy in the ATR mode confirms the presence of protein interactions but also rules out that this constitutes the unique reason for the evolution of the mobile fraction with the surface coverage. We also find that the diffusion coefficient, at small surface concentration, is more than 1 order of magnitude smaller on PSS than on PAH ending films, the diffusion coefficients being, respectively, equal to 6.2 × 10 -11 cm 2 /s and 2 × 10 -9 cm 2 /s. A tentative model based on the wrapping of HSA molecules by PAH chains and bridging between the chains by both polyelectrolytes is proposed to explain the observed features. Finally, we also determine the diffusion coefficient of HSA embedded in PSS/PAH multilayers. We find that the diffusion coefficient of HSA embedded in -PAH-HSA-PAH-type multilayers is close to that determined when HSA is adsorbed on PAH terminating films. When HSA is embedded in -PSS-HSA-PSS-type films the diffusion coefficient is independent of the HSA surface concentration and is surprisingly slightly larger than when HSA is adsorbed on PSS terminating films, 1.1 × 10 -10 cm 2 /s compared to 6.2 × 10 -11 cm 2 /s.

Research paper thumbnail of Integrating Microtissues in Nanofiber Scaffolds for Regenerative Nanomedicine

Research paper thumbnail of Active Nanomaterials to Meet the Challenge of Dental Pulp Regeneration

Research paper thumbnail of Build-up of Polypeptide Multilayer Coatings with Anti-Inflammatory Properties Based on the Embedding of Piroxicam–Cyclodextrin Complexes

Advanced Functional Materials, 2004

... Px into the multilayers, we used a charged cyclodextrin molecule, 6A-carboxymethylthio-β-cycl... more ... Px into the multilayers, we used a charged cyclodextrin molecule, 6A-carboxymethylthio-β-cyclo-dextrin (cCD, see Scheme 1b), to form Px±cyclodextrin com-plexes (cCD±Px). ... The com-plexes were then embedded in poly(L-glutamic acid) (PGA)/ poly(L-lysine) (PLL) multilayers ...

Research paper thumbnail of Active implant combining human stem cell microtissues and growth factors for bone-regenerative nanomedicine

Nanomedicine (London, England), 2015

Mesenchymal stem cells (MSCs) from adult bone marrow provide an exciting and promising stem cell ... more Mesenchymal stem cells (MSCs) from adult bone marrow provide an exciting and promising stem cell population for the repair of bone in skeletal diseases. Here, we describe a new generation of collagen nanofiber implant functionalized with growth factor BMP-7 nanoreservoirs and equipped with human MSC microtissues (MTs) for regenerative nanomedicine. By using a 3D nanofibrous collagen membrane and by adding MTs rather than single cells, we optimize the microenvironment for cell colonization, differentiation and growth. Furthermore, in this study, we have shown that by combining BMP-7 with these MSC MTs in this double 3D environment, we further accelerate bone growth in vivo. The strategy described here should enhance the efficiency of therapeutic implants compared with current simplistic approaches used in the clinic today based on collagen implants soaked in bone morphogenic proteins.

Research paper thumbnail of Active Nanomaterials to Meet the Challenge of Dental Pulp Regeneration

Research paper thumbnail of Synthesis of Selectively13C-Labelled Bilin Compounds

Eur J Org Chem, 2007

A series of open-chain tetrapyrroles, each carrying one or more 13 C-labels in its three ring-bri... more A series of open-chain tetrapyrroles, each carrying one or more 13 C-labels in its three ring-bridging methine groups, were synthesized. These compounds - [5-, [10-, and [15-13 C]phycocyanobilins (PCB), [10-13 C]-phytochromobilin, and [10,15-13 C 2 ]-PCB -were each obtained by a convergent route, starting with the four pyrrole building blocks, with the initial formation of the left and the right halves of the tetrapyrrole separately, followed by a final condensation of the two dipyrrole units to yield the target bilin compound. The

Research paper thumbnail of Integrating Microtissues in Nanofiber Scaffolds for Regenerative Nanomedicine

Research paper thumbnail of Double compartmented and hybrid implant outfitted with well-organized 3D stem cells for osteochondral regenerative nanomedicine

Nanomedicine (London, England), 2015

Articular cartilage repair remains challenging, because most clinical failures are due to the lac... more Articular cartilage repair remains challenging, because most clinical failures are due to the lack of subchondral bone regeneration. We report an innovative approach improving cartilage repair by regenerating a robust subchondral bone, supporting articular cartilage. We developed a compartmented living implant containing triple-3D structure: stem cells as microtissues for embryonic endochondral development mimic, nanofibrous collagen to enhance mineralization for subchondral bone and alginate hydrogel for cartilage regeneration. This system mimics the natural gradient of the osteochondral unit, using only one kind of stem cell, targeting their ability to express specific bone or cartilage proteins. Mineralization gradient of articular cartilage and the natural 'glue' between subchondral bone and cartilage were reproduced in vitro.

Research paper thumbnail of Ditopic binding of nucleotides by heptakis(6-hydroxyethylamino-6-deoxy)-β-cyclodextrin

Journal of The Chemical Society-perkin Transactions 2, 1998

The potential of heptakis (6-hydroxyethylamino-6-deoxy)-β-cyclodextrin (1) as a ditopic receptor ... more The potential of heptakis (6-hydroxyethylamino-6-deoxy)-β-cyclodextrin (1) as a ditopic receptor capable of electrostatic interaction and hydrogen bonding by its amino side-chains, together with inclusion in its hydrophobic cavity, has been assessed for nucleotides as ...

Research paper thumbnail of A persubstituted cationic beta-cyclodextrin for chiral separations

Analytical chemistry, 1997

The applications of a novel polycationic derivative of beta-cyclodextrin (beta-CD), heptakis(6-hy... more The applications of a novel polycationic derivative of beta-cyclodextrin (beta-CD), heptakis(6-hydroxyethylamino-6-deoxy-beta-cyclodextrin) (beta-CD-EA), as a chiral host--guest additive for the enantioseparation of various classes of chiral anionic analytes are presented. The cationic beta-CD described in this paper is persubstituted with seven ethanolamine side arms at the primary rim of each cyclodextrin (CD) molecule. It is found that the electrophoretic mobility of beta-CD-EA can be adjusted to influence the chiral selectivity by changing the pH of the background electrolyte. Most of the observed CD capillary zone electrophoresis (CZE) separations of anionic drugs and herbicides were accomplished in the pH range of 4.0-7.0 with a reverse polarity configuration. At pH 5.0, enantioseparation of a mixture of three structurally related antiinflammatory agents (fenoprofen, flurbiprofen, and ibuprofen) was possible in about 30 min. However, other chiral acids, such as a series of phe...

Research paper thumbnail of Cyclodextrin as a Template for Molecular Assembly: Formation of Heterodimers Between a Polyamino- and a Polysulfonato-β-Cyclodextrin

ABSTRACT A poly(hydroxyethylamino)- and a poly(sulfonatophenyloxy)-ß-cyclodextrin derivative, bea... more ABSTRACT A poly(hydroxyethylamino)- and a poly(sulfonatophenyloxy)-ß-cyclodextrin derivative, bearing opposite ionic charges, have been shown by potentiometric titration to form stable pH-dependent heterodimers with each other in water. The formation constants of these dimers show that a very stable assembly is formed between the fully deprotonated sulfonato derivative and the fully protonated amino derivative (log Ka = 8.5), which constitutes the assembly of multiple extended atomic groupings on cyclodextrin as template.

Research paper thumbnail of Amphiphilic 6-S-alkyl-6-thiocyclodextrins: unimolecular micellar and reverse micellar behaviour

Journal of the Chemical Society, Perkin Transactions 2, 1998

ABSTRACT Micellar behaviour of the amphiphilic 6-S-alkyl-6-thiocyclomaltooligosaccharid (2) in ch... more ABSTRACT Micellar behaviour of the amphiphilic 6-S-alkyl-6-thiocyclomaltooligosaccharid (2) in chloroform has been measured by use of the fluorescent probe 8-anilinonaphthalene-1-sulfonate (ANS) as guest molecule, as well as by water-chloroform interfacial tension measurements. At low concentrations the amphiphiles show behaviour consistent with their being oligomers of monosaccharide amphiphiles, or `unimolecular micelles&#39;. Thus, with ANS, 1:1 complexes are formed for which the association constants are in proportion to the length of the chains. At higher concentrations, the long-chained (C-16, C-18) alkylthioeyclodextrins form inverted micellar aggregates. The NMR shift changes associated with inclusion of 1-naphthol indicate that even in these aggregates, the carbohydrate cavity plays a part in complexation, while the hydrophobic chains act as extensions of the more hydrophobic primary-hydroxy side of the cavity.

Research paper thumbnail of Stabilizing Effects of Various Polyelectrolyte Multilayer Films on the Structure of Adsorbed/Embedded Fibrinogen Molecules:  An ATR−FTIR Study †

The Journal of Physical Chemistry B, 2001

The structural changes in fibrinogen as a consequence of its adsorption onto the surface of or it... more The structural changes in fibrinogen as a consequence of its adsorption onto the surface of or its embedding into the interior of poly(allylamine hydrochloride) (PAH) or poly(styrenesulfonate) (PSS) multilayers are investigated by means of attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy. It is found that both adsorption and embedding preserve the secondary structure of the fibrinogen molecules. Furthermore, the interactions of the polyelectrolytes with the protein molecules prevent their aggregation, especially in the embedded state, at room temperature. Thus, it seems that the structure and the biological activity of proteins adsorbed on or embedded in polyelectrolyte multilayers could largely be preserved, which opens up great perspectives in the design of new bioactive surfaces. The nature and the extent of the polyelectrolyte-protein interactions are further studied via analysis of the thermotropic responses of the different architectures. It is found that both PAH-and PSS-terminated polyelectrolyte multilayers can elevate the onset temperature of the structural changes in adsorbed/embedded fibrinogen molecules by about 5°C as compared with that for fibrinogen in solution. These polyelectrolytes also broaden the thermally induced structural transitions in the adsorbed/embedded fibrinogen molecules. The magnitude of these thermally induced structural changes is polyelectrolyte-and architecture-dependent. Whereas multilayer PAH-fibrinogen and multilayer PSS-fibrinogen constructions exhibit roughly the same large-scale thermally induced structural changes, in all architectures where fibrinogen is embedded the scale of these structural changes is restricted. The restriction becomes stronger as the presence of PSS at the polyelectrolyte-fibrinogen interfaces increases (PAH-fib-PAH < PAH-fib-PSS ≈ PSS-fib-PAH < PSS-fib-PSS). In the PSS-fib-PSS arrangement, the secondary structure of fibrinogen as determined from its infrared spectrum changes only slightly up to 90°C. The underlying processes of the thermally induced structural changes is, in addition, different for fibrinogen molecules adsorbed onto or embedded into PAH-terminated polyelectrolyte multilayers. A tentative model based on "encapsulation" of the embedded protein by the polyelectrolytes is proposed to explain the observed features. † Part of the special issue "Howard Reiss Festschrift".

Research paper thumbnail of Ditopic binding of nucleotides by heptakis(6-hydroxyethylamino-6-deoxy)-β-cyclodextrin

Journal of the Chemical Society, Perkin Transactions 2, 1998

The potential of heptakis (6-hydroxyethylamino-6-deoxy)-β-cyclodextrin (1) as a ditopic receptor ... more The potential of heptakis (6-hydroxyethylamino-6-deoxy)-β-cyclodextrin (1) as a ditopic receptor capable of electrostatic interaction and hydrogen bonding by its amino side-chains, together with inclusion in its hydrophobic cavity, has been assessed for nucleotides as ...

Research paper thumbnail of Complexation of Pr3+, Eu3+, Yb3+ and Th4+ ions by calixarene carboxylates

Journal of the Chemical Society, Dalton Transactions, 1997

J. Chem. Soc., Dalton Trans., 1997, Pages 329–334 ... Complexation of Pr3+, Eu3+, Yb3+ and Th4+ i... more J. Chem. Soc., Dalton Trans., 1997, Pages 329–334 ... Complexation of Pr3+, Eu3+, Yb3+ and Th4+ ions by calixarene carboxylates* ... Françoise Arnaud-Neu,a Suzane Cremin,b Steve Harris,c M. Anthony McKervey,b Marie-José Schwing-Weill,a Pascale Schwintéa and ...

Research paper thumbnail of A living thick nanofibrous implant bifunctionalized with active growth factor and stem cells for bone regeneration

International Journal of Nanomedicine, 2015

Research paper thumbnail of Amphiphilic Cyclodextrin Complexation of Clofazimine

Journal of Inclusion Phenomena, 2003

ABSTRACT The cyclodextrin amphiphilesheptakis[6-(1&#39;-sulfonato-3&#39;-propyl)-6-thio-2... more ABSTRACT The cyclodextrin amphiphilesheptakis[6-(1&#39;-sulfonato-3&#39;-propyl)-6-thio-2,3-di-O-acetyl]--cyclodextrin,heptakis[6-(6&#39; -sulfonato-2&#39;-benzimidazolyl)-6-thio-2,3-di-O-acetyl]--cyclodextrin, and heptakis[6-(-D-glucosyl)-6-thio-2,3-di-O-acetyl]--cyclodextrin have been shown to form aggregates in water by fluorescencemeasurements on the binding of 2-anilinonaphthalene, and by laserlight-scattering measurements. Estimates of aggregation number have been obtained.These aggregates successfully incorporate clofazimine, a lipophilic heterocyclic drug,and increase its water solubility by a factor of 30 to 50.

Research paper thumbnail of Selective alkali-metal cation complexation by chemically modified calixarenes. Part 4. Effect of substituent variation on the Na+/K+ selectivity in the ester series and X-ray crystal structure of the trifluoroethyl ester

Journal of the Chemical Society, Perkin Transactions 2, 1992

ABSTRACT The cation complexing abilities of a series of p-tert-butylcalix[4]arenes bearing ligati... more ABSTRACT The cation complexing abilities of a series of p-tert-butylcalix[4]arenes bearing ligating ester groups in the cone conformation have been assessed by stability constant measurements in methanol and extraction studies from water into dichloromethane. The cations studied were Na+ and K+ and variations in the ester function (CO2R) included R = methyl, ethyl, n-butyl, tert-butyl, benzyl, phenyl, phenacyl, methoxyethyl, trifluoroethyl, methylthioethyl and prop-2-ynyl. The effect of replacing one or two ester functions in the tetraethyl ester by methyl ester, carboxylic acid, ketone and amide functions was also studied. Selectivities for Na+ relative to K+ in stability constants range from 2 to 2500, the phenacyl derivative having the highest selectivity. X-Ray diffraction analysis was used to probe the conformation of the trifluoroethyl ester 11. Crystals of 11 are monoclinic, space group P21/n, in a cell of dimensions a= 13.987(2), b= 16.194(3), c= 27.630(5)Å; β= 98.70(1)°; R= 0.077 for 3172 observed data. The compound possesses a distorted cone conformation.

Research paper thumbnail of Complexation Mechanism of Bovine Serum Albumin and Poly(allylamine hydrochloride)

The Journal of Physical Chemistry B, 2002

ABSTRACT The mechanism of aggregation of bovine serum albumin (BSA) by poly(allylamine) hydrochlo... more ABSTRACT The mechanism of aggregation of bovine serum albumin (BSA) by poly(allylamine) hydrochloride (PAH) is investigated as a function of the mixing ratio r defined as the ratio of the number of BSA molecules and PAH chains present in the solution, under pH conditions of strong binding between the two partners. It is found that as r increases the turbidity first increases, passes through a maximum at a value rmax before decreasing again. For small and large values of r, one forms small aggregates in the 10 nanometer size range, whereas at rmax, the size of the aggregates becomes of the order of micrometers. The structure of the aggregates appears to be independent of the history of the systems but depends only on the value of r despite the strong BSA/PAH binding. The desaggregation of the large aggregates formed at rmax by the addition of BSA or PAH is shown to be an isenthalpic process and is thus entirely entropically driven. Moreover, we prove that rmax corresponds to the state of the system where both the PAH chains and the BSA molecules interact one with each other, both with their maximum number of interaction points per molecule. This explains the independence of rmax on the BSA or PAH concentration in the solution and why it varies linearly with the molecular weight of the polyelectrolyte. Moreover, we show that at rmax, all the BSA and PAH molecules present in the solution are involved in the aggregates. At small (respectively large) values of r, the aggregates appear positively (respectively negatively) charged, corresponding to a charge excess at the surface of the aggregates. Finally, it is found that the protein/polyelectrolyte interaction is endothermic, indicating that the BSA/PAH binding must thus be entropically driven. The binding enthalpy of BSA molecules with PAH chains for r &lt; rmax is of the order of 400 kJ·mol-1 of BSA molecules for solutions containing less than 0.1M of NaCl. The effect of the salt concentration of the solution on the binding process is also briefly discussed.

Research paper thumbnail of Dynamical Behavior of Human Serum Albumin Adsorbed on or Embedded in Polyelectrolyte Multilayers

The Journal of Physical Chemistry B, 2002

We investigate the lateral diffusion of Human Serum Albumin-Fluorescein Isothiocyanate (HSA) adso... more We investigate the lateral diffusion of Human Serum Albumin-Fluorescein Isothiocyanate (HSA) adsorbed "on" or embedded "in" poly(sodium 4-styrenesulfonate)/poly(allylamine hydrochloride) (PSS/PAH) multilayers. Special attention is brought to the evolution of the diffusion coefficient with the surface HSA concentration. We find that while on PSS terminating films the diffusion coefficient of adsorbed HSA is independent of the protein surface concentration in the explored range, it decreases strongly with the surface concentration when HSA is adsorbed on PAH ending films. On both films, the mobile fraction of adsorbed protein molecules decreases when the surface concentration increases. At low surface coverage, up to 90% of the adsorbed protein molecules are mobile both on PSS and PAH terminating films. The decrease of the mobile fraction with the HSA surface concentration is more pronounced on PSS than on PAH reaching, respectively, 50% and 70% of mobile HSA molecules at high surface coverage. This behavior is typical for protein aggregation. Infrared spectroscopy in the ATR mode confirms the presence of protein interactions but also rules out that this constitutes the unique reason for the evolution of the mobile fraction with the surface coverage. We also find that the diffusion coefficient, at small surface concentration, is more than 1 order of magnitude smaller on PSS than on PAH ending films, the diffusion coefficients being, respectively, equal to 6.2 × 10 -11 cm 2 /s and 2 × 10 -9 cm 2 /s. A tentative model based on the wrapping of HSA molecules by PAH chains and bridging between the chains by both polyelectrolytes is proposed to explain the observed features. Finally, we also determine the diffusion coefficient of HSA embedded in PSS/PAH multilayers. We find that the diffusion coefficient of HSA embedded in -PAH-HSA-PAH-type multilayers is close to that determined when HSA is adsorbed on PAH terminating films. When HSA is embedded in -PSS-HSA-PSS-type films the diffusion coefficient is independent of the HSA surface concentration and is surprisingly slightly larger than when HSA is adsorbed on PSS terminating films, 1.1 × 10 -10 cm 2 /s compared to 6.2 × 10 -11 cm 2 /s.