Search

Eugenol is a phenolic monoterpenoid, emplyed in this study to obtain bio-based antimicrobial and antioxidant methacrylate polymers.

This study combines the use of corn starch and Tetradesmus obliquus microalgae for the production of antioxidant starch films as flexible packaging material. Starch was plasticized with glycerol and blended with 1 w% polyallylamine chosen as an agent to modify the film physical properties. The addition of polyallylamine improved film water stability and water vapor transmission rate as well as mechanical stiffness and tenacity. The dried Tetradesmus obliquus microalgae, which showed an EC50 value of 2.8 mg/mg DPPH (2.2-Diphenyl-1-picrylhydrazyl radical), was then used as antioxidant filler. The addition of microalgae provided the films with good antioxidant activity, which increased with microalgae content increasing. To our knowledge, this is the first study reporting the development of sustainable bioactive packaging films composed of almost 100% starch, and follows the European union’s goals on plastics strategy concerning the promotion of bio-based, compostable plastics and the setting up of approaches to prevent food waste with a simple plastic packaging.

Nanoparticle (NP) drug delivery systems are known to potentially enhance the efficacy of therapeutic agents. As for antimicrobial drugs, therapeutic solutions against drug-resistant microbes are urgently needed due to the worldwide antimicrobial resistance issue. Usnic acid is a widely investigated antimicrobial agent suffering from poor water solubility. In this study, polymer nanoparticles based on polyglycerol adipate (PGA) grafted with polycaprolactone (PCL) were developed as carriers for usnic acid. We demonstrated the potential of the developed systems in ensuring prolonged bactericidal activity against a model bacterial species, Staphylococcus epidermidis. The macromolecular architecture changes produced by PCL grafted from PGA significantly influenced the drug release profile and mechanism. Specifically, by varying the length of PCL arms linked to the PGA backbone, it was possible to tune the drug release from a burst anomalous drug release (high PCL chain length) to a slow diffusion-controlled release (low PCL chain length). The developed nanosystems showed a prolonged antimicrobial activity (up to at least 7 days) which could be used in preventing/treating infections occurring at different body sites, including medical device-related infection and mucosal/skin surface, where Gram-positive bacteria are commonly involved.

The development of low-cost and eco-friendly materials for the removal of pollutants from water is one of the main modern challenges. For this purpose, molecularly imprinted polymers were prepared under optimized conditions starting from chitosan (CS), chemically or ionically modified with glycidyl methacrylate (GMA) or itaconic acid (ITA), respectively. 2,4-Dichlorophenoxyacetic acid (2,4-D) was used as a template, obtaining the CS_GMA and CS_ITA series. The influence of the template concentration on the MIPs’ (molecularly imprinted polymers) morphology, thermal behaviour and swelling ability, as well as on the 2,4-D removal capacity, were analyzed. The amount of the template used for the imprinting, together with the different permeability of the matrices, were the key factors driving the analyte uptake process. Despite the good performance shown by the non-imprinted CS_GMA sample, the best results were obtained when CS_GMA was imprinted with the highest amount (5%) of template (CS_GMA_5). This system was also more efficient when consecutive adsorption experiments were carried out. In addition, CS_GMA_5 had a desorption efficiency of 90–100% when a low pesticide concentration was used. These findings suggest that the presence of imprinted cavities could be useful in improving the performance of sorbent materials making CS_GMA_5 a possible candidate for 2,4-D removal., This research was funded by the Sapienza University of Rome, through a grant to A.P. (RM11916B6F8A0DF6).

This article focuses on the study related to the estimation of packaging material properties of cellulose–wax nanocomposite using molecular dynamics simulation (MDS). Cellulose based packaging material is gaining lot of importance due to its good material properties and low cost. Cellulose with small amount of plant-derived wax (nonacosane-10-ol and nonacosane-5,10-diol) offers higher mechanical strength and modulus of elasticity compared to the conventional synthetic polymer materials. In this article, in addition to the estimation of mechanical properties, the thermal stability of the proposed ecofriendly cellulose–wax composite is evaluated by estimating the glass transition temperature which essentially provides critical information on the glassy state and rubbery state of this biopolymer. The glass transition temperature of this composite changes significantly compared to that of pure cellulose (which also suffers from poor mechanical strength). Transport properties such as diffusion volume and diffusion coefficient of oxygen, nitrogen, and water are estimated using the results obtained from MDS. The diffusion coefficients of these species within the cellulose–wax composite are analyzed using the diffusion volume and interaction energies of these constituents with the wax and cellulose.

Solid-phase extraction (SPE) coupled to LC/MS/MS analysis is a valid approach for the determination of organic micropollutants (OMPs) in liquid samples. To remove the greatest number of OMPs from environmental matrices, the development of innovative sorbent materials is crucial. Recently, much attention has been paid to inorganic nanosystems such as graphite-derived materials. Graphene oxide has been employed in water-purification processes, including the removal of several micropollutants such as dyes, flame retardants, or pharmaceutical products. Polysaccharides have also been widely used as convenient media for the dispersion of sorbent materials, thanks to their unique properties such as biodegradability, biocompatibility, nontoxicity, and low cost. In this work, chitosan–graphene oxide (CS_GO) composite membranes containing different amounts of GO were prepared and used as sorbents for the SPE of pesticides. To improve their dimensional stability in aqueous medium, the CS_GO membranes were surface crosslinked with glutaraldehyde. The composite systems were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, swelling degree, contact angle, and mechanical measurements. As the GO content increased, a decrease in surface homogeneity, an improvement of mechanical properties, and a reduction of thermal stability of the CS-based membranes were observed. The increased dimensional stability in water, together with the presence of high GO amounts, made the prepared composite membranes more efficacious than the ones based just on CS in isolating and preconcentrating different hydrophilic/hydrophobic pollutants.

Here, we present a one-pot procedure for the preparation of hyaluronic acid (HA) sulfonated hydrogels in aqueous alkaline medium. The HA hydrogels were crosslinked using 1,4-butanedioldiglycidyl ether (BDDE) alone, or together with N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid (Bes), as a safe sulfonating agent. Conditions for the simultaneous reaction of HA with BDDE and Bes were optimized and the resulting hydrogels were characterized under different reaction times (24, 72, and 96 h). The incorporation of sulfonic groups into the HA network was proven by elemental analysis and FTIR spectroscopy and its effect on water uptake was evaluated. Compared with the non-sulfonated sample, sulfonated gels showed improved mechanical properties, with their compressive modulus increased from 15 to 70 kPa, higher stability towards hyaluronidase, and better biocompatibility to 10T1/2 fibroblasts, especially after the absorption of collagen. As main advantages, the procedure described represents an easy and reproducible methodology for the fabrication of sulfonated hydrogels, which does not require toxic chemicals and/or solvents.

In this study, a new scaffold fabrication method based on the combination of a series of stabilization processes was set up to obtain chitosan scaffolds with improved mechanical properties for regeneration of load-bearing tissues. Specifically, thermally induced phase separation (TIPS) of chitosan solutions was used to obtain an open structure which was then stabilized by freeze-gelation and photo cross-linking. Freeze-gelation combined with freeze-drying permitted to obtain a porous structure with a 95 μm-mean pore size suitable for osteoblast cells' housing. Photo-crosslinking improved by ca. three times the scaffold compressive modulus, passing from 0,8 MPa of the uncrosslinked scaffolds to 2,2 MPa of the crosslinked one. Hydrated crosslinked scaffolds showed a good elastic response, with an 80% elastic recovery for at least 5 consecutive compressive cycles. The herein reported method has the advantage to not require the use of potentially toxic cross-linking agents and may be extended to other soft materials.

Background: Antioxidants are multifaceted molecules playing a crucial role in several cellular functions. There is by now a well-established knowledge about their involvement in numerous processes associated with aging, including vascular damage, neurodegenerative diseases and cancer. An emerging area of application has been lately identified for these compounds in relation to the recent findings indicating their ability to affect biofilm formation by some microbial pathogens, including Staphylococcus aureus, Streptococcus mutans, and Pseudomonas aeruginosa. Methods: A structured search of bibliographic databases for peer-reviewed research literature was performed using a focused review question. The quality of retrieved papers was appraised using standard tools. Results: One hundred sixty-five papers extracted from pubmed database and published in the last fifteen years were included in this review focused on the assessment of the antimicrobial and antibiofilm activity of antioxidant compounds, including vitamins, flavonoids, non-flavonoid polyphenols, and antioxidant polymers. Mechanisms of action of some important antioxidant compounds, especially for vitamin C and phenolic acids, were identified. Conclusion: The findings of this review confirm the potential benefits of the use of natural antioxidants as antimicrobial/antibiofilm compounds. Generally, gram-positive bacteria were found to be more sensitive to antioxidants than gram-negatives. Antioxidant polymeric systems have also been developed mainly derived from functionalization of polysaccharides with antioxidant molecules. The application of such systems in clinics may permit to overcome some issues related to the systemic delivery of antioxidants, such as poor absorption, loss of bioactivity, and limited half-life. However, investigations focused on the study of antibiofilm activity of antioxidant polymers are still very limited in number and therefore they are strongly encouraged in order to lay the foundations for application of antioxidant polymers in treatment of biofilm-based infections.

Wound healing is a dynamic process that can be seriously delayed by many factors including infectious complications. The development of dressings with intrinsic wound healing activity and/or releasing bioactive compounds may help with addressing such an issue. In this study, hyaluronic acid (HA) at different percentages (1&ndash, 35%) was used to modify chitosan (CS) biological and physico-chemical properties in order to obtain 2D-matrices able to promote healing and protect from infection. HA incorporation in the CS matrix decreased film transparency and homogeneity, but improved film water uptake and surface wettability. The water vapor transmission rate (WVTR) increased up to a 5% HA content, where it reached the highest value (672 g/m2 day), and decreased for higher HA contents. At all of the tested HA concentrations, HA affected mechanical properties providing matrices more flexible than pure CS with benefit for wound care. Pure CS films permitted S. epidermidis adhesion and biofilm formation. That was not true for CS/HA matrices, where HA at concentrations equal to or greater than 5% was able to avoid S. epidermidis adhesion. Fibroblasts adhesion also took benefit from the HA presence in the film, especially at 5% content, where the best adhesion and proliferation was found.

The inclusion of pH-sensitive components in liposome formulations can allow a more controlled and efficient release in response to low pH typical of some pathological tissues and/or subcellular compartments. On the other hand decorating the surface of liposomes with sugar moieties attributes to lipid vesicles specificity toward lectins, sugar-binding proteins overexpressed in many tumor tissues. A novel multifunctional pH-sensitive glucosylated amphiphile was synthesized and characterized as pure aggregate component and in mixtures with a natural phospholipid. The comparison of the properties of the new glucosylated amphiphile with respect to those of a previously described cationic structural analogue demonstrates that the pH-sensitivity can strongly affect drug release, lipid organization, as well as the exposure of the glucose residues on liposome surface and their ability to interact with Concanavalin A, a plant lectin used as model system.

A novel hydroxytyrosol-based polyacrylate polymer material (pAcHTy) endowed with metal ion adsorption ability was obtained by free radical polymerization of a monomer containing a hydroxytyrosol precursor (tyrosol). Hydroxytyrosol (HTy) is the main natural polyphenolic compound with antioxidant activity occurring in virgin olive oil and in olive oil wastewaters. pAcHTy showed a good chelating activity with respect to Cu2+ ions, especially at pH 6 where short equilibrium times and high adsorption capacity were observed (146 mg/g). From thermodynamic parameters, it has been found that the sorption process was spontaneous at low temperature and exothermic in nature. The adsorption process has been studied by employing three simplified kinetic models, including a pseudo-first-order equation, pseudo-second-order equation, and intraparticle diffusion equation. Kinetic parameters, rate constants, equilibrium sorption capacities, and related correlation coefficients, for each kinetic model, were calculated and discussed. It was shown that the adsorption of Cu2+ ions could be described by the pseudo-second-order equation, suggesting that the adsorption process is presumable a chemisorption. The pAcHTy polymer could find an important application in the medical field, particularly in chelation therapy as well as in the wastewater and drinking water treatment plants.

Despite advances in material sciences and clinical procedures for surgical hygiene, medical device implantation still exposes patients to the risk of developing local or systemic infections. The development of efficacious antimicrobial/antifouling materials may help with addressing such an issue. In this framework, polyethylene glycol (PEG)-grafted segmented polyurethanes were synthesized, physico-chemically characterized, and evaluated with respect to their bacterial fouling-resistance properties. PEG grafting significantly altered the polymer bulk and surface properties. Specifically, the PEG-grafted polyurethanes possessed a more pronounced hard/soft phase segregated microstructure, which contributed to improving the mechanical resistance of the polymers. The better flexibility of the soft phase in the PEG-functionalized polyurethanes compared to the pristine polyurethane (PU) was presumably also responsible for the higher ability of the polymer to uptake water. Additionally, dynamic contact angle measurements evidenced phenomena of surface reorganization of the PEG-functionalized polyurethanes, presumably involving the exposition of the polar PEG chains towards water. As a consequence, Staphylococcus epidermidis initial adhesion onto the surface of the PEG-functionalized PU was essentially inhibited. That was not true for the pristine PU. Biofilm formation was also strongly reduced.

The rapid increase in the emergence of antibiotic-resistant bacterial strains combined with a dwindling rate of discovery of novel antibiotic molecules has lately created an alarming issue worldwide [...]

Protein mussel-inspired adhesive polymers, characterized by the presence of catechol groups, possess superior muco-adhesive properties and have great potentiality in wound healing. Suitable materials for wound dressing should properly combine muco-adhesiveness and antimicrobial activity. In this work, catechol-functionalized chitosan was obtained by reaction with hydrocaffeic acid (HCAF), in order to investigate how catechol introduction at different content could affect the intrinsic antimicrobial activity of the polymer itself. Unexpectedly, an enhancement of chitosan antimicrobial activity was observed after catechol functionalization, with a fourfold reduction in the polymer minimum inhibitory concentration versus Staphylococcus epidermidis. Additionally, a commercial wound dressing coated with one of the synthesized CS-HCAF derivatives showed a significant reduction in the adhesion of S. epidermidis compared to the uncoated dressing (3-log reduction). The CS-HCAF derivatives also showed an interesting antioxidant property (EC50 ranging from 20 to 60 μg/mL), which further confirms the potentiality of these materials as wound dressings. © 2017 Elsevier Ltd

Biocompatible and degradable poly(α-hydroxy acids) are one of the most widely used materials in scaffolds for tissue engineering. Nevertheless, they often need surface modification to improve interaction with cells. Aminolysis is a common method to increase the polymer hydrophilicity and to introduce surface functional groups, able to covalently link or absorb, through electrostatic interaction, bioactive molecules or macromolecules. For this purpose, multi-functional amines, such as diethylenediamine or hexamethylenediamine are used. However, common drawbacks are their toxicity and the introduction of positive charges on the surface. Thus, these kind of modified surfaces are unable to link directly proteins, such as collagens, a promising substrate for many cell types, in particular chondrocytes and osteoblasts. In this work, poly(L-lactide) (PLLA) film surface was labelled with negatively charged sulfonate groups by grafting taurine (TAU) through an aminolysis reaction. The novel modified PLLA film (PLLA-TAU) was able to interact directly with collagen. The reaction was carried out in mild conditions by using a solution of tetrabutylammonium salt of TAU in methanol. ATR-FTIR, XPS and contact angle measurements were used to verify the outcome of the reaction. After the exchange of tetrabutylamonium cation with Na+, collagen was absorbed on the TAU grafted PLLA film (PLLA-TAU-COLL). In vitro biological tests with human primary chondrocytes showed that PLLA-TAU and PLLA-TAU-COLL improved cell viability and adhesion, compared to the unmodified polymer, suggesting that these modifications make PLLA substrate suitable for cartilage repair.

The aim of the present work was to study the possibility of building a porous scaffold for tissue engineering with a new bottom-up approach, obtained by assembling two-dimensional-micro, one-dimensional-nano sized poly(L-lactide) lamellar single crystals. This choice was dictated by the fact that polymer single crystals have structural and morphological features which can be exploited for chemical surface modifications to give a system characterized by a high specific active surface area. Indeed, the outermost amorphous regions can undergo functionalization reactions easily, whereas the inner, relatively inaccessible and inert crystalline core ensures morphological and mechanical stability. The assembling method employed to give the porous structures is based on a mould pressing, salt leaching technique and was found to be facile and versatile. In the first part of this paper we report the experimental results obtained to find the best conditions to achieve a suitable frame in terms of morphology, porosity and mechanical properties. In the second part of the paper, we describe the biological tests performed by using mouse fibroblasts seeded onto scaffolds prepared from pristine and surface hydrolysed lamellae. The results show that the samples obtained are suitable for sustaining cells which can proliferate and reach the inner pores of the scaffold containing hydrolysed single crystals much better than those prepared from pristine lamellae. Copyright © 2012 Society of Chemical Industry

In recent years the employment of implantable medical devices has increased remarkably, notwithstanding that microbial infections are a frequent complication associated with their use. Different strategies have been attempted to overcome this problem, including the incorporation of antimicrobial agents into the device itself. In this study a new approach to obtain intrinsically antimicrobial materials was developed. Polymer anionomers containing Ag(I), Cu(II), Zn(II), Al(III) and Fe(III) were prepared by neutralization of a carboxylated polyurethane. In the case of the PEUA-Ag, PEUA-Fe and PEUA-Cu ionomers the ion aggregates behaved as reinforcing filler particles, increasing the mechanical properties of the systems in terms of hardness and strength at break over the pristine carboxylated polymer. With the exception of the Al-containing polymer, all the other experimented ionomers showed satisfactory antimicrobial properties. The best antibacterial effect was obtained with the silver ion-containing polymer, which inhibited Staphylococcus epidermidis growth for up to 16 days. Ciprofloxacin was also adsorbed onto the above mentioned ionomers. A synergistic effect of the antibiotic and silver ions on bacterial growth inhibition was observed for at least 25 days.

BACKGROUND: Micellar systems are widely applied as reactors to encapsulate inorganic nanoparticles in polymeric materials. However, only low inorganic contents and microscale dimensions are often achieved. RESULTS: The adsorption of albumin protein on ferrite nanoparticles permits to increase the stability of inorganic dispersions in water by inhibiting particle flocculation. Subsequent glutaraldehyde addition induces protein crosslinking and ferrite entrapment. Polymer–ferrite composite nanoparticles were obtained in this way. The magnetic albumin nanoparticles (25 nm mean diameter) obtained contain about 40 wt% of ferrite and show superparamagnetic behaviour. The composite powder was successfully functionalized with a model drug and the biological activity was evaluated. CONCLUSION: Using a reverse micelle approach, ferrite–albumin composite nanoparticles with a high inorganic content were obtained. The method permits the formulation of biocompatible magnetic particles of nanoscale dimensions. The exhibited superparamagnetic behaviour permits to hypothesize an application of the powder composite as a carrier in biomedical technologies. Copyright © 2009 Society of Chemical Industry

Heparin–Toluidine Blue (C.I. Basic Blue 17) interaction was studied using UV–vis spectroscopic analysis of the titration of the functional groups present on the polyanion chain. The study took into consideration both the pH and relative amount of the dye as a function of the Heparin repeat unit number; formation of a dye/polysaccharide aggregate was studied under the same conditions and structural models of the two types of aggregates were proposed. As a consequence of such an investigation a new Heparin determination methodology was developed.

The silver coating of polymers has been intensively investigated in the last few decades as an effective non-resistance-inducing strategy to prevent medical device-related infections. We have developed a completely new approach to incorporate silver ions in polymers by the synthesis of a carboxylated polyurethane able to coordinate Ag + . The obtained polymers possess mechanical properties suitable for the development of medical devices, without any risk of loss of activity. To minimize the risk of increasing antibiotic resistance, the metal ion-containing polymers are loaded with ciprofloxacin, which possesses a different mechanism of antimicrobial action, thus a system able to inhibit Staphylococcus epidermidis and Pseudomonas aeruginosa growth for at least one month is developed. SEM images showing a mature S. epidermidis biofilm on the surface of the carboxylated polyurethane (left) and the surface of the silver ion-containing polyurethane free from bacterial colonization (right) after 48 h of incubation.

Vinyl polymers such as poly(ethylene-co-vinyl alcohol) (EVAL) and polyallylamine (PALA) both commercially available were chemically modified by introduction of carboxylic and sulfonate groups to obtain polymeric materials with improved haemocompatibility. The introduction of carboxyl groups was carried out by reaction of EVAL's hydroxy groups with acrylonitrile followed by basic hydrolysis of -CN groups. Amino groups of PALA were transformed into sulfonate groups by reaction with pyridine-SO 3 complex. Influence of reagents molar ratio, temperature and reaction time on the carboxylation degree was evaluated. In particular, yields of 86% (EVAL-CN 0.52) and 30% (EVALCOOH 0.16) were obtained for the cyanoethylation and the hydrolysis reaction of the -CN groups, respectively, whereas a sulfonation of 24% of the PALA amino groups was found. The functionalised polymers were characterized by physicochemical measurements. Preliminary biological tests proved the importance of strong acidic groups on the anticoagulant properties of the polymeric materials.

Paola Di Bonito,1 Linda Petrone,1 Gabriele Casini,2 Iolanda Francolini,2 Maria Grazia Ammendolia,3 Luisa Accardi,1 Antonella Piozzi,2 Lucio D’Ilario,2 Andrea Martinelli2 1Department of Infectious, Parasitic and Immune-mediated Diseases, Italian National Institute of Health, 2Department of Chemistry, Sapienza University of Rome, Rome, Italy; 3Department of Technology and Health, Italian National Institute of Health, Rome, Italy 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 (PLLAsc) 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 (APLLAsc). Pristine and amino-functionalized PLLAsc 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 m2/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 PLLAsc adsorbed similar amounts of E7 protein, but in protein-release experiments E7-PLLAsc released a higher amount of protein than E7-APLLAsc. When the complexes were dried for observation by scanning electron microscopy, both samples showed a compact layer, but E7-APLLAsc showed greater roughness than E7-PLLAsc. Immunization experiments in mice showed that E7-APLLAsc induced a stronger E7-specific immune response when compared with E7-PLLAsc. Immunoglobulin G isotyping and interferon gamma analysis suggested a mixed Th1/Th2 immune response in both E7-PLLAsc-immunized and E7-APLLAsc-immunized mice. However, only the mice receiving E7-APLLAsc 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-APLLAsc could be used for development of an HPV16 therapeutic vaccine against HPV16-related tumors. Keywords: poly(L-lactide), lamellar crystals, human papillomavirus, HPV16-E7, therapeutic vaccine

In order to obtain polymers provided with improved haemocompatibility a commercial ethylene-vinyl alcohol copolymer (EVAL) was chemically modified by the introduction of different amounts of carboxylated groups. The carboxylation was carried out by reaction of the EVAL hydroxy groups with three different anhydrides. The influence of the reagents molar ratio on the functionalization degree was evaluated. The new terpolymers (EVAL–COOH) have been characterized by chemical and physico-chemical techniques as titration of the acidic groups, elemental analysis, Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis and 1 H-NMR.

Full Paper: In order to obtain polymers provided with improved haemocompatibility a commercial ethylene-vinyl alcohol copolymer (EVAL) was chemically modified by introduction of different amounts of sulfate groups. The sulfation reaction was carried out by the reaction was carried out by the reaction of hydroxy groups with two different sulfating reagents (CISO 3 H and PySO 3 ). The influence of the molar ratio of the reagents and the reaction time on the functionalization degree was evaluated also for elevated substitution degrees. No difference in the sulfation agents efficiency was noted. the new terpolymers (EVAL-SO 3 H) have been characterized by chemical and physico-chemical techniques as: titration of the acidic groups, Fourier Transform IR reflectrance spectroscopy (FTIR-ATR), differential scanning calometry (DSC), X-ray photoelectron spectroscopy (XPS° and 1 H-NMR. The haemocompatibility was evaluated by in vitro plasma coagulation (APTT) and platelet aggregation tests and is proved to be excellent for sulfation degrees higher than 35% of the hydroxylgroups of the polymer.

Hydrophobic terpolymers ethylene/vinyl alcohol/vinyl stearate, of three different compositions, have been obtained by reaction of a commercial ethylene/vinyl alcohol copolymer (EVAL) with stearoyl chloride at different molar ratios. The obtained polymers were characterized by means of 'H NMR, transmission FT-IR spectroscopy, differential scanning calorimetry and thermogravimetric analysis. The hydrophobic character of the film surfaces was investigated by IR-ATR and by determining their surface and critical tensions. It was seen that it increased with increasing degree of substitution of the hydroxy groups of EVAL.

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 μm-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 24h-old Staphylococcus epidermidis biofilm more efficaciously than free UA.

In order to prepare polymer surfaces of vinyl type, provided with long-term haemocompatibility, a commercial ethylene-vinyl alcohol copolymer (EVAL) was covalently heparinized, employing two different bifunctional reagents (adipoil chloride and hexamethylene diisocyanate). The amount and activity of the heparin bonded to the polymer films were evaluated as a function of the concentration of the heparin solutions employed. Also, the influence exerted by the presence of various hydrophilic 'spacing arms' of different molecular weights, either neutral or provided with electrical charge, was investigated. By in vitro measurements of activated partial thromboplastin time it was seen that all the heparinized samples possessed a high degree of haemocompatibility. For the sake of comparison, heparin was also bonded ionically to EVAL functionalized by introduction of quaternary ammonium groups bonded covalently (by adipoil chloride) to the hydroxyl groups of the polymer. It was seen that the covalent immobilization system provides the polymer surfaces with a superior haemocompatibility.

The special issue “Antimicrobial Polymers” includes research and review papers concerning the recent advances on preparation of antimicrobial polymers and their relevance to industrial settings and biomedical field. Antimicrobial polymers have recently emerged as promising candidates to fight microbial contamination onto surfaces thanks to their interesting properties. In this special issue, the main strategies pursued for developing antimicrobial polymers, including polymer impregnation with antimicrobial agents or synthesis of polymers bearing antimicrobial moieties, were discussed. The future application of these polymers either in industrial or healthcare settings could result in an extremely positive impact not only at the economic level but also for the improvement of quality of life.

Usnic acid, a potent antimicrobial and anticancer agent, poorly soluble in water, was complexed to novel antimicrobial polyacrylamides by establishment of strong acidic-base interactions. Thermal and spectroscopic analysis evidenced a molecular dispersion of the drug in the polymers and a complete drug/polymer miscibility for all the tested compositions. The polymer/drug complexes promptly dissolved in water and possessed a greater antimicrobial activity against Staphylococcus epidermidis than both the free drug and the polymer alone. The best results were obtained with the complex based on the lowest molecular weight polymer and containing a low drug content. Such a complex showed a larger inhibition zone of bacterial growth and a lower minimum inhibitory concentration (MIC) with respect to usnic acid alone. This improved killing effect is presumably due to the reduced size of the complexes that allows an efficient cellular uptake of the antimicrobial complexes. The killing effect extent seems to be not significantly dependent on usnic acid content in the samples.

The synthesis of new segmented polyurethanes containing as chain extender N-hexadecyl-2,2-bis(hydroxymethyl)propionamide (alone or with 1,4-butanediol at different mole ratios) is described. The degree of hydrophobicity and the glass transition temperatures Tg were found to be proportional to the alkyl chain content of the polymer. Also the amount of bonded albumin is proportional to the alkyl group content of the polymer, and platelet adhesion is remarkably lower for the 100% alkylated polymer (PEUHDA) than for the standard non-alkylated polyurethane (PEU). This behaviour was confirmed by SEM evaluation, showing a much lower degree of activation of platelets on albuminized PEUHDA films. It was not possible to ascertain with sufficient reliability a different behaviour, with respect to platelet adhesion, of the polymers containing alkyl chains in the range 9 ÷ 50 mol-%, due to the relatively high error of the evaluation systems.

The synthesis of new segmented polyurethanes containing different amounts of N,N-diethylaminoethyl-N′-2,2 hydroxymethylpropionamide, and able to bind, after suitable quaternization, high amounts of heparin, is described. The quaternization is carried out on organic solutions of the polymers. Polymers have been characterized by spectroscopic techniques (transmission and reflectance IR and 1H and 13C NMR), molecular weight measurements and differential scanning calorimetry. The heparin content of the polymer films was determined by a colorimetric system, and its biological activity was evaluated in vitro by activated partial thromboplastin time (APTT) measurements. The distribution of heparin on the surface and in bulk of the heparinized films was evaluated by scanning electron microscopy (SEM) combined with X-ray energy dispersive spectroscopy.

To obtain biodegradable amphiphilic block polymers for biomedical applications, a series of poly(ether-ester)s based on poly(ethylene oxide) and various hydrophobic/hydrophilic segment ratios were synthesized by the solution polymerization technique. The polyesters were characterized using 1H NMR spectroscopy, elemental analysis, gel permeation chromatography, differential scanning calorimetry, thermogravimetric analysis and compression stress–strain measurements. The composition of the poly(ether-ester)s agreed with the feed ratio. A study of the degree of phase segregation in the polymers evidenced that microphase mixing increases with the presence in the hydrophobic segments of polar groups able to establish interactions with the poly(ethylene oxide). This phase mixing increased the thermal stability of the acidic poly(ether-ester)s. Nanospheres for drug delivery with an average diameter of 50 nm were obtained by employing the acidic poly(ether-ester) showing less microphase segregation, while a scaffold structure with a homogeneous and highly interconnected porosity and an average pore size of approximately 15 µm for tissue engineering was prepared using the more hydrophobic copolymer not possessing functional groups. Compression mechanical measurements carried out on the scaffold showed that the more hydrophobic copolymer was suitable for tissue engineering applications. In order to obtain polymers employable both in drug delivery and in tissue engineering a series of block poly(ether-ester)s showing various phase segregations were synthesized by varying the hydrophobic/hydrophilic segment ratio. Copyright © 2010 Society of Chemical Industry

The synthesis of a hydroxylated polyurethane, by reduction with diborane of the corresponding carboxylated polymer, is described. The starting polyurethane, of the segmented type, contains as chain extender dihydroxymethylpropionic acid. Various conditions for hydrogenation of the carboxy group have been investigated, and it was possible to transform quantitatively carboxy into hydroxymethyl groups, without hydrogenolytic reactions affecting the main chain of the polymer. The obtained polymer was characterized by chemical titration, viscometry, i.r., NMR and DSC.

Poly(L-lactide) (PLLA) single crystals grown from dilute solution were employed for the first time in the preparation of drug delivery systems. PLLA single crystals were selectively hydrolyzed with HCl to provide the lamellar surface with carboxylic groups, which were employed to graft Dipyridamole (Dip), chosen as a model drug. The influence of the hydrolysis conditions on the single crystals properties was investigated by FT-IR, DSC and GPC measurements, while Dip grafting yield and drug release in lipase solution were followed by UV-vis spectroscopy. Dip was slowly delivered over a few days, suggesting the potential use of PLLA single crystals as controlled drug release carriers for either oral or parenteral injection administration.

The electrical characteristics of poly( p -phenylene sulphide) single crystals, grown from dilute solutions in diphenyl ether, have been investigated before and after doping with I 2 and AlCl 3 . The resulting modifications in the thermal and i.r. spectroscopic properties are described. The results indicate marked anisotropy of the transport properties in the crystals, with preferential movement of the charges in the direction perpendicular to the chain axis.

The glass transition of poly(phenylene sulfide) (PPS) has been examined by Fourier transform infrared spectroscopy (FT-IR). The relative absorbances A 1470 A 1072 , A 1383 A 1072 , A 1091 A 1072 and A 1009 A 1072 vs temperature showed a change of the slope at T = 75 °C, corresponding to the glass transition temperature of PPS when heated at 0.5 K/min. The results obtained have been discussed in the light of the possible causes.

In order to prepare polymers provided with better haemocompatibility with respect both to the coagulative cascade and to platelet aggregation and activation, we have synthesized new polyurethanes containing in the chain extender [di-(2-hydroxyethyl) hexa-decylamine (DHHA)] both a long chain alkyl group (able to bond albumin) and a tertiary ammonium group able, after suitable quaternization reaction, to bind ionically significant amounts of heparin. The amounts of heparin and albumin bonded to the polymer films were determined spectrophotometrically. A biological in vitro evaluation of the heparinized and albuminized films was also carried out, with respect to the blood coagulation factors (by APTT measurements) and to platelet adhesion. For the sake of comparison, polyurethanes containing as chain extenders two different monomers (containing, respectively, the long alkyl and the quaternary ammonium group), and polymer blends consisting of these copolymers, were also prepared and evaluated as above. It was seen that the type of the adsorption sequence for albumin and heparin, respectively, onto films of the various homopolymers, copolymers and blends, plays an important role in their biological properties.

In this paper we want to report the results obtained in our study of the cold-crystallization kinetics of PPS samples quenched from the melt state and analyzed in the crystallization temperature range 90–112°C. Such a wide range was explored by employing three different experimental techniques: the first one was the usual Differential Scanning Calorimetry (DSC), for the highest temperature range, the second and third ones were the less conventional FT-IR spectroscopy and energy dispersive X-ray diffraction (EDXD), able to explore the lowest temperature range. The experimental data obtained by the three above mentioned methods have been all together analyzed by means of the Avrami equation. FT-IR and EDXD have also allowed us to study the secondary crystallization process of PPS, which otherwise could not be observed just with the DSC technique. The overall crystallization process of such a polymer has been interpreted in the light of the model proposed by Ravindranath and Jog to explain the crystallization of the polymer from the melt state.