Lucio D'Ilario | Università degli Studi "La Sapienza" di Roma (original) (raw)

Papers by Lucio D'Ilario

Research paper thumbnail of Antioxidant Hydroxytyrosol-Based Polyacrylate with Antimicrobial and Antiadhesive Activity Versus Staphylococcus Epidermidis

Advances in Experimental Medicine and Biology, 2015

The accumulation of reactive oxygen species (ROS) in microbial biofilms has been recently recogni... more The accumulation of reactive oxygen species (ROS) in microbial biofilms has been recently recognized to play a role in promoting antibiotic resistance in biofilm-growing bacteria. ROS are also over-produced when a medical device is implanted and they can promote device susceptibility to infection or aseptic loosening. High levels of ROS seem also to be responsible for the establishment of chronic wounds.In this study, a novel antioxidant polyacrylate was synthesized and investigated in terms of antimicrobial and antibiofilm activity. The polymer possesses in side-chain hydroxytyrosol (HTy), that is a polyphenolic compound extracted from olive oil wastewaters.The obtained 60 nm in size polymer nanoparticles showed good scavenging and antibacterial activity versus a strain of Staphylococcus epidermidis. Microbial adherence assays evidenced that the hydroxytyrosol-containing polymer was able to significantly reduce bacterial adhesion compared to the control. These findings open novel perspective for a successful use of this antioxidant polymer for the prevention or treatment of biofilm-based infections as those related to medical devices or chronic wounds.

Research paper thumbnail of A study on the location of radiation induced cross‐links in polyethylene single crystals by selective degradation

Die Makromolekulare Chemie

ABSTRACT

Research paper thumbnail of Self-Assembly of Catecholic Moiety-Containing Cationic Random Acrylic Copolymers

The Journal of Physical Chemistry B, 2015

Amphiphilic polyelectrolytes (APEs), exhibiting particular self-association properties in aqueous... more Amphiphilic polyelectrolytes (APEs), exhibiting particular self-association properties in aqueous media, can be used in different industrial applications, including drug delivery systems. Their typical core-shell structure (micelle) depends on the balance of interactions between hydrophobic and ionizable monomer units. In this work, the structure of amphiphilic cationic random copolymers, obtained by employing different molar ratios of two acrylic monomers, one bearing in the side chain a tertiary amine (N,N-diethylethylendiamine, DED) and the other one a hydrophobic catecholic group (hydroxytyrosol, HTy), was investigated by atomistic molecular dynamics (MD) simulation, (1)H NMR analysis, dynamic light scattering (DLS), and zeta potential measurements. The structures of p(AcDED-co-AcHTy) copolymers were compared with that of the cationic homopolymer (pAcDED). MD simulation showed a chain folding in water solution of all polymer materials consistent with the degree of hydrophobicity of the chain, that increases with the number of aromatic residues. This phenomenon was induced by the interaction between the charged amine groups with water and by the associated attraction between aromatic rings inside the molecule. In addition, the p(AcDED-co-AcHTy) 70/30 copolymer had a marked tendency to self-assemble as shown by the radial distribution function among catechol carbon atoms. Electrical conductivity measurements evidenced a micellar arragment for all of the synthesized copolymers, and specially for p(AcDED-co-AcHTy) 70/30, a flower micelle structure seem to be more likely. The stacking interactions among catecholic groups present in the side chain of the copolymers reduced the size and charge density specially for the p(AcDED-co-AcHTy) 70/30 copolymer. Finally, the good antimicrobial activity of all copolymers confirmed the right reached amphiphilic balance. Indeed, a considerable reduction of the minimum inhibitory concentration (from 100 μg/mL to 40 μg/mL for pAcDED and p(AcDED-co-AcHTy) 70/30, respectively) was obtained by introducing a hydrophobic group molar fraction of 0.3.

Research paper thumbnail of Amino-functionalized poly(L-lactide) lamellar single crystals as a valuable substrate for delivery of HPV16-E7 tumor antigen in vaccine development

International Journal of Nanomedicine, 2015

Background: Poly(l-lactide) (PLLA) is a biodegradable polymer currently used in many biomedical a... more Background: Poly(l-lactide) (PLLA) is a biodegradable polymer currently used in many biomedical applications, including the production of resorbable surgical devices, porous scaffolds for tissue engineering, nanoparticles and microparticles for the controlled release of drugs or antigens. The surfaces of lamellar PLLA single crystals (PLLA sc) were provided with amino groups by reaction with a multifunctional amine and used to adsorb an Escherichia coli-produced human papillomavirus (HPV)16-E7 protein to evaluate its possible use in antigen delivery for vaccine development. Methods: PLLA single crystals were made to react with tetraethylenepentamine to obtain amino-functionalized PLLA single crystals (APLLA sc). Pristine and amino-functionalized PLLA sc showed a two-dimensional microsized and one-dimensional nanosized lamellar morphology, with a lateral dimension of about 15-20 µm, a thickness of about 12 nm, and a surface specific area of about 130 m 2 /g. Both particles were characterized and loaded with HPV16-E7 before being administered to C57BL/6 mice for immunogenicity studies. The E7-specific humoral-mediated and cell-mediated immune response as well as tumor protective immunity were analyzed in mice challenged with TC-1 cancer cells. Results: Pristine and amino-functionalized PLLA sc adsorbed similar amounts of E7 protein, but in protein-release experiments E7-PLLA sc released a higher amount of protein than E7-APLLA sc. When the complexes were dried for observation by scanning electron microscopy, both samples showed a compact layer, but E7-APLLA sc showed greater roughness than E7-PLLA sc. Immunization experiments in mice showed that E7-APLLA sc induced a stronger E7-specific immune response when compared with E7-PLLA sc. Immunoglobulin G isotyping and interferon gamma analysis suggested a mixed Th1/Th2 immune response in both E7-PLLA sc-immunized and E7-APLLA sc-immunized mice. However, only the mice receiving E7-APLLA sc were fully protected from TC-1 tumor growth after three doses of vaccine. Conclusion: Our results show that APLLA single crystals improve the immunogenicity of HPV16-E7 and indicate that E7-APLLA sc could be used for development of an HPV16 therapeutic vaccine against HPV16-related tumors.

Research paper thumbnail of Calculation of the van der Waals potential energy for polyethylene and polytetrafluoroethylene as two-atom and three-atom chains: rotational freedom in the crystals

Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry, 1974

The van der Waals potential energy of polyethylene and polytetrafluoroethylene has been computed ... more The van der Waals potential energy of polyethylene and polytetrafluoroethylene has been computed as a function of both two and three angles of rotation around the bonds of the backbone chain, the bond lengths and valence angles being held fixed. The calculations show that there are more minima than is predicted by the 'equivalence principle'. The implications of these results are important in the crystalline polymers and in the physical chemistry of the polymer solutions as well as in statistical-mechanical theories. In addition the evaluation of the van der Waals potential energy in the crystal of polytetrafluoroethylene by rotating in phase the polymer chains around their helical axes suggests that, surprisingly, the macromolecules are free-rotating.

Research paper thumbnail of The crystal and molecular structure of N-(t-butyloxycarbonyl)-L-azetidine-2-carboxylic acid and conformational analysis of poly-(L-azetidinecarboxylic acid)

Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry, 1975

N-(t-Butyloxycarbonyl)-L-azetidine-2-carboxylic acid (CgHlsNO4, BACA) was chosen as a model compo... more N-(t-Butyloxycarbonyl)-L-azetidine-2-carboxylic acid (CgHlsNO4, BACA) was chosen as a model compound to determine the geometry of the monomeric unit of poly-(L-azetidinecarboxylic acid), hereafter referred to as PACA. BACA is orthorhombic, space group P2~2~21, with a= 8"249 (8), b = 10-904 (9), c= 12"327 (11)~, Z=4. The structure was determined from 748 X-ray intensities measured on a Siemens automated diffractometer with Mo Ke radiation by the 0/20 scan technique. The structure was solved by direct methods with MULTAN and refined by least-squares calculations to a final R of 0.050. The azetidine ring and the oxycarbonyl group linked to the nitrogen atom are in the same plane, the greatest atomic deviation being 0.05 A,. The molecu!ar packing is characterized by hydrogen bonds along e and by van der Waals interactions, the strongest of which are between methyl and methylene groups. The bond distances and angles of BACA were employed to perform the conformational analysis of PACA as a function of two angles of rotation. The potential-energy calculations show the presence of two minima, markedly deeper than the others, in agreement with spectroscopic results.

Research paper thumbnail of Partially sulfonated ethylene-vinyl alcohol copolymer as new substrate for 3,4-ethylenedioxythiophene vapor phase polymerization

Journal of Polymer Science Part B: Polymer Physics, 2014

Research paper thumbnail of ChemInform Abstract: An Improved Procedure for the Preparation of 2-Halo-1,3- and -1,4- Diethynylbenzenes and Their Oxidative Polymerization. Synthesis and Characterization of the Corresponding Polymers via Oxidative Polymerization

Research paper thumbnail of Crystallization of short aliphatic chains. II. Example of even fold surface with adjacent fold reentry and of a transition to chain extension

Journal of Polymer Science Part A-2: Polymer Physics, 1972

... References 1. A. Keller and Y. Udagawa, J. Polym. Sci. A-2, 10,221 (1972). 2. D. M. Sadler an... more ... References 1. A. Keller and Y. Udagawa, J. Polym. Sci. A-2, 10,221 (1972). 2. D. M. Sadler and A. Keller, Kolloid 2.2. Polym., 239,641 (1970). 3. A. KeUer andY. Udagawa, J. Polym. Sci. A-2,8,19 (1970). 4. D. H. R. Barton, HP Faro, EP Serebryakov, and N. F. Woolsey, J. Chem. ...

Research paper thumbnail of Release behavior and antibiofilm activity of usnic acid-loaded carboxylated poly(l-lactide) microparticles

European Journal of Pharmaceutics and Biopharmaceutics, 2014

The use of controlled drug delivery systems could give a significant contribution to the improvem... more The use of controlled drug delivery systems could give a significant contribution to the improvement of therapies against biofilm-based infections. The aim of this study was to develop polymer microparticles, based on carboxylated poly(L-lactide)s, to be employed as carriers for usnic acid (UA), a poorly soluble drug possessing antiviral, antiproliferative and wide spectrum antimicrobial activity. Thanks to polymer surfactant-like structure, 2.4 lm-in-size microparticles were obtained by a surfactant-free oil-in-water emulsion/evaporation method. UA was encapsulated into these microparticles with a high loading efficiency (80%). The drug release kinetics was found to be temperature dependent (the released dose increasing with temperature) and showed bimodal release behavior. By polarized optical microscopy observations and the application of kinetics models, the initial burst effect was attributed to the delivery of the drug amorphous fraction while the slower release occurring for longer times to the crystalline one, both entrapped in the polymer amorphous phase. UA-loaded microparticles were able to promote the killing of a 24 hold Staphylococcus epidermidis biofilm more efficaciously than free UA.

Research paper thumbnail of Doping Kinetics of Polyacetylene in the Short Range

Le Journal de Physique Colloques, 1983

/l/, a été étudiée dans les premières minutes du contact entre le dopant et le PA en suivant la v... more /l/, a été étudiée dans les premières minutes du contact entre le dopant et le PA en suivant la variation des propriétés électriques de conductivité et spectroscopique d'absorbance IR à 1400 Cm" et à 1023 et 750 cm~. Les données expérimentales ont mis en évidence l'existence, dans cet intervalle de temps, de au moins trois étapes de réaction caractérisées par des constantes cinétiques qui diffèrent par des ordres de grandeur. On a essayé d'élaborer un modèle cinétique du processus de dopage et on a calculé les valeurs des énergies d'activation.

Research paper thumbnail of Thermoplastic elastomers: Structural and morphological aspects of ether–esteramide copolymers

Journal of Polymer Science: Polymer Physics Edition, 1985

ABSTRACT

Research paper thumbnail of Conformational aspects of a “very simple” chain: Polyacetylene

Journal of Polymer Science: Polymer Chemistry Edition, 1983

... Polyacetylene ENRICO CERNIA and LUCIO D'ILARIO,* ASSORENI, Monterotondo (Rome), Italy ..... more ... Polyacetylene ENRICO CERNIA and LUCIO D'ILARIO,* ASSORENI, Monterotondo (Rome), Italy ... The conformational analysis was done to allow rotations around the 1.46 8, CC bonds only. Angular in-crements of 10' were used and a cutoff distance of 8 8, was assumed. ...

Research paper thumbnail of A ‘composite membrane’ bioreactor

Journal of Molecular Catalysis, 1989

Research paper thumbnail of A composite membrane bioreactor

Journal of Molecular Catalysis, 1989

Research paper thumbnail of Proceedings in Life Sciences

Journal of Molecular Catalysis, 1978

Research paper thumbnail of Potential-Energy Calculations of Ethylene-Butadiene Copolymers

Journal of Polymer Science Part a-Polymer Chemistry, 1975

The copolymer ethylene-butadiene (PEBU) was investigated by van der Waals potential energy .calcu... more The copolymer ethylene-butadiene (PEBU) was investigated by van der Waals potential energy .calculations as a function of four internal rotation angles. The butadiene/ethylene molar ratio was assumed to be very small, no greater than 0.25. The energy values corresponding to the fully extended chain of PEBU and polyethylene (PE) are nearly equal, so that the replacement of a-H&-CH2unit with the trans-HC=CHgroup (TDB) in P E crystals can be consflered feasible, as found by x-ray diffraction measurements. The three deepest minima of the van der Waals energy correspond to folded chains, with the double bonds lying in the fold parts. Similar calculations carried out on a PE chain point out that TDB behaves as fold-supporting. The two energetically more favorable conformations of PEBU reproduce rather well the (110) and (200) folds in P E crystals. The path of the (110) + (200) transition does not appear to be hindered by a large potential barrier. If the-HC=CHgroup is in the cis conformation, no stable folded chain can be obtained by means of only four intramolecular degrees of freedom. On the basis of these results it is reasonable to suppose that many TDB's could be located on the surface of PEBU single crystals.

Research paper thumbnail of X-Ray and Conformational Study of Kapton-H

Journal of Polymer Science Part B-Polymer Physics, 1976

Potential energy calculations were performed on the isolated chain of Kapton H (KH) in order to o... more Potential energy calculations were performed on the isolated chain of Kapton H (KH) in order to obtain information on the most probable conformations. A model with a C-0-C angle of 130° and with the segments joining the ether oxygens forming a planar zigzag chain satisfactorily fits the x-ray experimental data. Although the equatorial reflections are very few and diffuse, it seems likely that the space group is P21 and the unit cell parameters are a = 4.66 A, b = 32.9 A, c = 5.96 A, p = 100". The observed density is in agreement with two monomers in the unit cell. An intrachain vector distribution map was computed by rotating (angle 0) the pyromellitic acid diimide (DIPA) unit about the N-C bond in the KH monomer. This map was compared with a one-dimensional Patterson synthesis calculated along b, the fiber axis, to establish the value of 0. Van der Waals' energy calculations were subsequently accomplished in the crystal as a function of 0 and of the rotation around the helical axis of the KH chains. The results allowed us to choose a reasonable macromolecular conformation and packing in the crystal. KH is mainly ordered along the fiber axis but shows little order in the packing of adjacent helixes. The macromolecules are held together by Van der Waals' and, probably, by charge-transfer forces.

Research paper thumbnail of Physicochemical Study of Crystals of Ethylene-Butadiene Copolymers

Journal of Polymer Science Part a-Polymer Chemistry, 1978

Ethylene-butadiene (PEBU) copolymer with low percentage of butadiene was previously investigated ... more Ethylene-butadiene (PEBU) copolymer with low percentage of butadiene was previously investigated by van der Waals potential energy calculations. The trans-HC=CH-group (TDB) was found to show fold-supporting behavior, so that it was supposed that many TDB's were located on the surface of PEBU single crystals under favorable conditions of TDB concentration and of thickness of crystal platelets. In order to verify this hypothesis, three PEBU samples with a butadiene/ (ethylene + butadiene) molar ratio of 2.3% (B), 3.6% (C), and 4.6% (D), by assuming that the-HC==CH-groups are all trans, were studied and compared with a polyethylene (PE) sample (A). Samples A, B, C, and D were grown isothermally at temperatures of 50,55,60,61,70,71,75, and 80°C from dilute xylene solutions. Infrared, differential scanning calorimetry (DSC), small-angle x-ray scattering (SAXS), bromination kinetics, and density measurements were performed. B, C, and D lamellar crystals show a long spacing L nearly equal to that of A at crystallization temperatures T, of 50 and 60°C. For T, 1 70°C, the fold period of samples B, C, and D increases more rapidly than that of A in the order D > C > B. The melting temperature T,,, and the enthalpy of fusion AHf decrease with increasing content of butadiene, except for B and C, which show nearly equal T,,, and AHf values. Two peaks appear in the fusion curves at temperatures TI and Tz, T I > Tz. The area of the peak a t T2 increases with the butadiene content, and, in the same sample, with T,. Results of bromination in suspension of B, C, and D single crystals, crystallid in the range 50-7loC, indicate that a high percentage of TDBs react on the fold surfaces. The chemical attack is more successful with crystals grown in the range 60-66"C, and, in the case of sample C, as much as 81% of the TDB's are consumed. The density of the samples increases with both T, and TDB percentage. On the basis of these observed results a simple model for PEBU is proposed. It is supposed that the copolymerization reaction leads to the formation of defects, consisting of one (b), two (bb), three (bbb), or more sequential molecules of butadiene, almost homogeneously distributed along a macromolecular chain. At very small percentage of butadiene, b defects prevail. The addition of further butadiene gives rise mainly to bb defects, and so on. Thus each kind of defect characterizes PEBU copolymers with a certain butadiene/ethylene molar ratio. The experimental data, valid for low butadienel ethylene molar ratios, agree with this reasonable model and with the potential energy calculations.

Research paper thumbnail of Chain Folding in Crystalline Syndiotactic Polyvinyl-Chloride)

Journal of Polymer Science Part B-Polymer Physics, 1979

Potential-energy calculations seem to be capable of providing information about the structural ch... more Potential-energy calculations seem to be capable of providing information about the structural characteristics of the folds in crystalline polymers. This paper deals with the conformational analysis of syndiotactic poly(viny1 chloride) (PVC) chains in order to reproduce satisfactory models of folding in the (OlO), (400), and (210) crystallographic planes. The results imply that tight (010) and (400) folds and, hence, adjacent reentry may occur. The folds are probably stabilized by a weak hydrogen-bond type of interaction. Moreover-CHCl-CHpCH-z-CHCl-segments in the folds have been taken into account, thus obtaining more energetically favored models. The crystal lattice energy has been computed as a function of the PVC unit-cell parameters a and b, releasing the fold's constraint of the stems. The energy minimum corresponds to a noticeable decrease of a in comparison with the experimental value, although the potentials used in the calculations are hard and have van der Waals radii greater than those usually accepted. As a consequence it seems reasonable to suppose that the folds strongly influence the PVC crystal packing and do not allow better interatomic contacts between stems to form.

Research paper thumbnail of Antioxidant Hydroxytyrosol-Based Polyacrylate with Antimicrobial and Antiadhesive Activity Versus Staphylococcus Epidermidis

Advances in Experimental Medicine and Biology, 2015

The accumulation of reactive oxygen species (ROS) in microbial biofilms has been recently recogni... more The accumulation of reactive oxygen species (ROS) in microbial biofilms has been recently recognized to play a role in promoting antibiotic resistance in biofilm-growing bacteria. ROS are also over-produced when a medical device is implanted and they can promote device susceptibility to infection or aseptic loosening. High levels of ROS seem also to be responsible for the establishment of chronic wounds.In this study, a novel antioxidant polyacrylate was synthesized and investigated in terms of antimicrobial and antibiofilm activity. The polymer possesses in side-chain hydroxytyrosol (HTy), that is a polyphenolic compound extracted from olive oil wastewaters.The obtained 60 nm in size polymer nanoparticles showed good scavenging and antibacterial activity versus a strain of Staphylococcus epidermidis. Microbial adherence assays evidenced that the hydroxytyrosol-containing polymer was able to significantly reduce bacterial adhesion compared to the control. These findings open novel perspective for a successful use of this antioxidant polymer for the prevention or treatment of biofilm-based infections as those related to medical devices or chronic wounds.

Research paper thumbnail of A study on the location of radiation induced cross‐links in polyethylene single crystals by selective degradation

Die Makromolekulare Chemie

ABSTRACT

Research paper thumbnail of Self-Assembly of Catecholic Moiety-Containing Cationic Random Acrylic Copolymers

The Journal of Physical Chemistry B, 2015

Amphiphilic polyelectrolytes (APEs), exhibiting particular self-association properties in aqueous... more Amphiphilic polyelectrolytes (APEs), exhibiting particular self-association properties in aqueous media, can be used in different industrial applications, including drug delivery systems. Their typical core-shell structure (micelle) depends on the balance of interactions between hydrophobic and ionizable monomer units. In this work, the structure of amphiphilic cationic random copolymers, obtained by employing different molar ratios of two acrylic monomers, one bearing in the side chain a tertiary amine (N,N-diethylethylendiamine, DED) and the other one a hydrophobic catecholic group (hydroxytyrosol, HTy), was investigated by atomistic molecular dynamics (MD) simulation, (1)H NMR analysis, dynamic light scattering (DLS), and zeta potential measurements. The structures of p(AcDED-co-AcHTy) copolymers were compared with that of the cationic homopolymer (pAcDED). MD simulation showed a chain folding in water solution of all polymer materials consistent with the degree of hydrophobicity of the chain, that increases with the number of aromatic residues. This phenomenon was induced by the interaction between the charged amine groups with water and by the associated attraction between aromatic rings inside the molecule. In addition, the p(AcDED-co-AcHTy) 70/30 copolymer had a marked tendency to self-assemble as shown by the radial distribution function among catechol carbon atoms. Electrical conductivity measurements evidenced a micellar arragment for all of the synthesized copolymers, and specially for p(AcDED-co-AcHTy) 70/30, a flower micelle structure seem to be more likely. The stacking interactions among catecholic groups present in the side chain of the copolymers reduced the size and charge density specially for the p(AcDED-co-AcHTy) 70/30 copolymer. Finally, the good antimicrobial activity of all copolymers confirmed the right reached amphiphilic balance. Indeed, a considerable reduction of the minimum inhibitory concentration (from 100 μg/mL to 40 μg/mL for pAcDED and p(AcDED-co-AcHTy) 70/30, respectively) was obtained by introducing a hydrophobic group molar fraction of 0.3.

Research paper thumbnail of Amino-functionalized poly(L-lactide) lamellar single crystals as a valuable substrate for delivery of HPV16-E7 tumor antigen in vaccine development

International Journal of Nanomedicine, 2015

Background: Poly(l-lactide) (PLLA) is a biodegradable polymer currently used in many biomedical a... more Background: Poly(l-lactide) (PLLA) is a biodegradable polymer currently used in many biomedical applications, including the production of resorbable surgical devices, porous scaffolds for tissue engineering, nanoparticles and microparticles for the controlled release of drugs or antigens. The surfaces of lamellar PLLA single crystals (PLLA sc) were provided with amino groups by reaction with a multifunctional amine and used to adsorb an Escherichia coli-produced human papillomavirus (HPV)16-E7 protein to evaluate its possible use in antigen delivery for vaccine development. Methods: PLLA single crystals were made to react with tetraethylenepentamine to obtain amino-functionalized PLLA single crystals (APLLA sc). Pristine and amino-functionalized PLLA sc showed a two-dimensional microsized and one-dimensional nanosized lamellar morphology, with a lateral dimension of about 15-20 µm, a thickness of about 12 nm, and a surface specific area of about 130 m 2 /g. Both particles were characterized and loaded with HPV16-E7 before being administered to C57BL/6 mice for immunogenicity studies. The E7-specific humoral-mediated and cell-mediated immune response as well as tumor protective immunity were analyzed in mice challenged with TC-1 cancer cells. Results: Pristine and amino-functionalized PLLA sc adsorbed similar amounts of E7 protein, but in protein-release experiments E7-PLLA sc released a higher amount of protein than E7-APLLA sc. When the complexes were dried for observation by scanning electron microscopy, both samples showed a compact layer, but E7-APLLA sc showed greater roughness than E7-PLLA sc. Immunization experiments in mice showed that E7-APLLA sc induced a stronger E7-specific immune response when compared with E7-PLLA sc. Immunoglobulin G isotyping and interferon gamma analysis suggested a mixed Th1/Th2 immune response in both E7-PLLA sc-immunized and E7-APLLA sc-immunized mice. However, only the mice receiving E7-APLLA sc were fully protected from TC-1 tumor growth after three doses of vaccine. Conclusion: Our results show that APLLA single crystals improve the immunogenicity of HPV16-E7 and indicate that E7-APLLA sc could be used for development of an HPV16 therapeutic vaccine against HPV16-related tumors.

Research paper thumbnail of Calculation of the van der Waals potential energy for polyethylene and polytetrafluoroethylene as two-atom and three-atom chains: rotational freedom in the crystals

Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry, 1974

The van der Waals potential energy of polyethylene and polytetrafluoroethylene has been computed ... more The van der Waals potential energy of polyethylene and polytetrafluoroethylene has been computed as a function of both two and three angles of rotation around the bonds of the backbone chain, the bond lengths and valence angles being held fixed. The calculations show that there are more minima than is predicted by the 'equivalence principle'. The implications of these results are important in the crystalline polymers and in the physical chemistry of the polymer solutions as well as in statistical-mechanical theories. In addition the evaluation of the van der Waals potential energy in the crystal of polytetrafluoroethylene by rotating in phase the polymer chains around their helical axes suggests that, surprisingly, the macromolecules are free-rotating.

Research paper thumbnail of The crystal and molecular structure of N-(t-butyloxycarbonyl)-L-azetidine-2-carboxylic acid and conformational analysis of poly-(L-azetidinecarboxylic acid)

Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry, 1975

N-(t-Butyloxycarbonyl)-L-azetidine-2-carboxylic acid (CgHlsNO4, BACA) was chosen as a model compo... more N-(t-Butyloxycarbonyl)-L-azetidine-2-carboxylic acid (CgHlsNO4, BACA) was chosen as a model compound to determine the geometry of the monomeric unit of poly-(L-azetidinecarboxylic acid), hereafter referred to as PACA. BACA is orthorhombic, space group P2~2~21, with a= 8"249 (8), b = 10-904 (9), c= 12"327 (11)~, Z=4. The structure was determined from 748 X-ray intensities measured on a Siemens automated diffractometer with Mo Ke radiation by the 0/20 scan technique. The structure was solved by direct methods with MULTAN and refined by least-squares calculations to a final R of 0.050. The azetidine ring and the oxycarbonyl group linked to the nitrogen atom are in the same plane, the greatest atomic deviation being 0.05 A,. The molecu!ar packing is characterized by hydrogen bonds along e and by van der Waals interactions, the strongest of which are between methyl and methylene groups. The bond distances and angles of BACA were employed to perform the conformational analysis of PACA as a function of two angles of rotation. The potential-energy calculations show the presence of two minima, markedly deeper than the others, in agreement with spectroscopic results.

Research paper thumbnail of Partially sulfonated ethylene-vinyl alcohol copolymer as new substrate for 3,4-ethylenedioxythiophene vapor phase polymerization

Journal of Polymer Science Part B: Polymer Physics, 2014

Research paper thumbnail of ChemInform Abstract: An Improved Procedure for the Preparation of 2-Halo-1,3- and -1,4- Diethynylbenzenes and Their Oxidative Polymerization. Synthesis and Characterization of the Corresponding Polymers via Oxidative Polymerization

Research paper thumbnail of Crystallization of short aliphatic chains. II. Example of even fold surface with adjacent fold reentry and of a transition to chain extension

Journal of Polymer Science Part A-2: Polymer Physics, 1972

... References 1. A. Keller and Y. Udagawa, J. Polym. Sci. A-2, 10,221 (1972). 2. D. M. Sadler an... more ... References 1. A. Keller and Y. Udagawa, J. Polym. Sci. A-2, 10,221 (1972). 2. D. M. Sadler and A. Keller, Kolloid 2.2. Polym., 239,641 (1970). 3. A. KeUer andY. Udagawa, J. Polym. Sci. A-2,8,19 (1970). 4. D. H. R. Barton, HP Faro, EP Serebryakov, and N. F. Woolsey, J. Chem. ...

Research paper thumbnail of Release behavior and antibiofilm activity of usnic acid-loaded carboxylated poly(l-lactide) microparticles

European Journal of Pharmaceutics and Biopharmaceutics, 2014

The use of controlled drug delivery systems could give a significant contribution to the improvem... more The use of controlled drug delivery systems could give a significant contribution to the improvement of therapies against biofilm-based infections. The aim of this study was to develop polymer microparticles, based on carboxylated poly(L-lactide)s, to be employed as carriers for usnic acid (UA), a poorly soluble drug possessing antiviral, antiproliferative and wide spectrum antimicrobial activity. Thanks to polymer surfactant-like structure, 2.4 lm-in-size microparticles were obtained by a surfactant-free oil-in-water emulsion/evaporation method. UA was encapsulated into these microparticles with a high loading efficiency (80%). The drug release kinetics was found to be temperature dependent (the released dose increasing with temperature) and showed bimodal release behavior. By polarized optical microscopy observations and the application of kinetics models, the initial burst effect was attributed to the delivery of the drug amorphous fraction while the slower release occurring for longer times to the crystalline one, both entrapped in the polymer amorphous phase. UA-loaded microparticles were able to promote the killing of a 24 hold Staphylococcus epidermidis biofilm more efficaciously than free UA.

Research paper thumbnail of Doping Kinetics of Polyacetylene in the Short Range

Le Journal de Physique Colloques, 1983

/l/, a été étudiée dans les premières minutes du contact entre le dopant et le PA en suivant la v... more /l/, a été étudiée dans les premières minutes du contact entre le dopant et le PA en suivant la variation des propriétés électriques de conductivité et spectroscopique d'absorbance IR à 1400 Cm" et à 1023 et 750 cm~. Les données expérimentales ont mis en évidence l'existence, dans cet intervalle de temps, de au moins trois étapes de réaction caractérisées par des constantes cinétiques qui diffèrent par des ordres de grandeur. On a essayé d'élaborer un modèle cinétique du processus de dopage et on a calculé les valeurs des énergies d'activation.

Research paper thumbnail of Thermoplastic elastomers: Structural and morphological aspects of ether–esteramide copolymers

Journal of Polymer Science: Polymer Physics Edition, 1985

ABSTRACT

Research paper thumbnail of Conformational aspects of a “very simple” chain: Polyacetylene

Journal of Polymer Science: Polymer Chemistry Edition, 1983

... Polyacetylene ENRICO CERNIA and LUCIO D'ILARIO,* ASSORENI, Monterotondo (Rome), Italy ..... more ... Polyacetylene ENRICO CERNIA and LUCIO D'ILARIO,* ASSORENI, Monterotondo (Rome), Italy ... The conformational analysis was done to allow rotations around the 1.46 8, CC bonds only. Angular in-crements of 10' were used and a cutoff distance of 8 8, was assumed. ...

Research paper thumbnail of A ‘composite membrane’ bioreactor

Journal of Molecular Catalysis, 1989

Research paper thumbnail of A composite membrane bioreactor

Journal of Molecular Catalysis, 1989

Research paper thumbnail of Proceedings in Life Sciences

Journal of Molecular Catalysis, 1978

Research paper thumbnail of Potential-Energy Calculations of Ethylene-Butadiene Copolymers

Journal of Polymer Science Part a-Polymer Chemistry, 1975

The copolymer ethylene-butadiene (PEBU) was investigated by van der Waals potential energy .calcu... more The copolymer ethylene-butadiene (PEBU) was investigated by van der Waals potential energy .calculations as a function of four internal rotation angles. The butadiene/ethylene molar ratio was assumed to be very small, no greater than 0.25. The energy values corresponding to the fully extended chain of PEBU and polyethylene (PE) are nearly equal, so that the replacement of a-H&-CH2unit with the trans-HC=CHgroup (TDB) in P E crystals can be consflered feasible, as found by x-ray diffraction measurements. The three deepest minima of the van der Waals energy correspond to folded chains, with the double bonds lying in the fold parts. Similar calculations carried out on a PE chain point out that TDB behaves as fold-supporting. The two energetically more favorable conformations of PEBU reproduce rather well the (110) and (200) folds in P E crystals. The path of the (110) + (200) transition does not appear to be hindered by a large potential barrier. If the-HC=CHgroup is in the cis conformation, no stable folded chain can be obtained by means of only four intramolecular degrees of freedom. On the basis of these results it is reasonable to suppose that many TDB's could be located on the surface of PEBU single crystals.

Research paper thumbnail of X-Ray and Conformational Study of Kapton-H

Journal of Polymer Science Part B-Polymer Physics, 1976

Potential energy calculations were performed on the isolated chain of Kapton H (KH) in order to o... more Potential energy calculations were performed on the isolated chain of Kapton H (KH) in order to obtain information on the most probable conformations. A model with a C-0-C angle of 130° and with the segments joining the ether oxygens forming a planar zigzag chain satisfactorily fits the x-ray experimental data. Although the equatorial reflections are very few and diffuse, it seems likely that the space group is P21 and the unit cell parameters are a = 4.66 A, b = 32.9 A, c = 5.96 A, p = 100". The observed density is in agreement with two monomers in the unit cell. An intrachain vector distribution map was computed by rotating (angle 0) the pyromellitic acid diimide (DIPA) unit about the N-C bond in the KH monomer. This map was compared with a one-dimensional Patterson synthesis calculated along b, the fiber axis, to establish the value of 0. Van der Waals' energy calculations were subsequently accomplished in the crystal as a function of 0 and of the rotation around the helical axis of the KH chains. The results allowed us to choose a reasonable macromolecular conformation and packing in the crystal. KH is mainly ordered along the fiber axis but shows little order in the packing of adjacent helixes. The macromolecules are held together by Van der Waals' and, probably, by charge-transfer forces.

Research paper thumbnail of Physicochemical Study of Crystals of Ethylene-Butadiene Copolymers

Journal of Polymer Science Part a-Polymer Chemistry, 1978

Ethylene-butadiene (PEBU) copolymer with low percentage of butadiene was previously investigated ... more Ethylene-butadiene (PEBU) copolymer with low percentage of butadiene was previously investigated by van der Waals potential energy calculations. The trans-HC=CH-group (TDB) was found to show fold-supporting behavior, so that it was supposed that many TDB's were located on the surface of PEBU single crystals under favorable conditions of TDB concentration and of thickness of crystal platelets. In order to verify this hypothesis, three PEBU samples with a butadiene/ (ethylene + butadiene) molar ratio of 2.3% (B), 3.6% (C), and 4.6% (D), by assuming that the-HC==CH-groups are all trans, were studied and compared with a polyethylene (PE) sample (A). Samples A, B, C, and D were grown isothermally at temperatures of 50,55,60,61,70,71,75, and 80°C from dilute xylene solutions. Infrared, differential scanning calorimetry (DSC), small-angle x-ray scattering (SAXS), bromination kinetics, and density measurements were performed. B, C, and D lamellar crystals show a long spacing L nearly equal to that of A at crystallization temperatures T, of 50 and 60°C. For T, 1 70°C, the fold period of samples B, C, and D increases more rapidly than that of A in the order D > C > B. The melting temperature T,,, and the enthalpy of fusion AHf decrease with increasing content of butadiene, except for B and C, which show nearly equal T,,, and AHf values. Two peaks appear in the fusion curves at temperatures TI and Tz, T I > Tz. The area of the peak a t T2 increases with the butadiene content, and, in the same sample, with T,. Results of bromination in suspension of B, C, and D single crystals, crystallid in the range 50-7loC, indicate that a high percentage of TDBs react on the fold surfaces. The chemical attack is more successful with crystals grown in the range 60-66"C, and, in the case of sample C, as much as 81% of the TDB's are consumed. The density of the samples increases with both T, and TDB percentage. On the basis of these observed results a simple model for PEBU is proposed. It is supposed that the copolymerization reaction leads to the formation of defects, consisting of one (b), two (bb), three (bbb), or more sequential molecules of butadiene, almost homogeneously distributed along a macromolecular chain. At very small percentage of butadiene, b defects prevail. The addition of further butadiene gives rise mainly to bb defects, and so on. Thus each kind of defect characterizes PEBU copolymers with a certain butadiene/ethylene molar ratio. The experimental data, valid for low butadienel ethylene molar ratios, agree with this reasonable model and with the potential energy calculations.

Research paper thumbnail of Chain Folding in Crystalline Syndiotactic Polyvinyl-Chloride)

Journal of Polymer Science Part B-Polymer Physics, 1979

Potential-energy calculations seem to be capable of providing information about the structural ch... more Potential-energy calculations seem to be capable of providing information about the structural characteristics of the folds in crystalline polymers. This paper deals with the conformational analysis of syndiotactic poly(viny1 chloride) (PVC) chains in order to reproduce satisfactory models of folding in the (OlO), (400), and (210) crystallographic planes. The results imply that tight (010) and (400) folds and, hence, adjacent reentry may occur. The folds are probably stabilized by a weak hydrogen-bond type of interaction. Moreover-CHCl-CHpCH-z-CHCl-segments in the folds have been taken into account, thus obtaining more energetically favored models. The crystal lattice energy has been computed as a function of the PVC unit-cell parameters a and b, releasing the fold's constraint of the stems. The energy minimum corresponds to a noticeable decrease of a in comparison with the experimental value, although the potentials used in the calculations are hard and have van der Waals radii greater than those usually accepted. As a consequence it seems reasonable to suppose that the folds strongly influence the PVC crystal packing and do not allow better interatomic contacts between stems to form.