Preparation and characterization of novel antibacterial castor oil-based polyurethane membranes for wound dressing application

Antimicrobial Efficacy of a Vegetable Oil Plasticizer in PVC Matrices

The growing prevalence of bacterial and viral infections, highlighted by the recent COVID-19 pandemic, urgently calls for new antimicrobial strategies. To this end, we have synthesized and characterized a novel fatty acid epoxy-ester plasticizer for polymers, named GDE. GDE is not only sustainable and user-friendly but also demonstrates superior plasticizing properties, while its epoxy components improve the heat stability of PVC-based matrices. A key feature of GDE is its ability to confer antimicrobial properties to surfaces. Indeed, upon contact, this material can effectively kill enveloped viruses, such as herpes simplex virus type 1 (HSV-1) and the β-coronavirus prototype HCoV-OC43, but it is ineffective against nonenveloped viruses like human adenovirus (HAdV). Further analysis using transmission electron microscopy (TEM) on HSV-1 virions exposed to GDE showed significant structural damage, indicating that GDE can interfere with the viral envelope, potentially causing leakage. Moreover, GDE demonstrates antibacterial activity, albeit to a lesser extent, against notorious pathogens such as Staphylococcus aureus and Escherichia coli. Overall, this newly developed plasticizer shows significant potential as an antimicrobial agent suitable for use in both community and healthcare settings to curb the spread of infections caused by microorganisms contaminating physical surfaces.

Antibacterial Host-Guest Intercalated LDH-Adorned Polyurethane for Accelerated Dermal Wound Healing

Curcumin has a limited clinical application because of its extremely poor accessibility. In the present study, improved curcumin bioavailability within a castor oil polyurethane/layered double hydroxide (LDH) wound cover was achieved by preparing a curcumin p-sulfonic acid calix[4]arene (SC4A) inclusion complex. Then, it was utilized to intercalate MgAl-layered double hydroxide (MgAl-LDH) nanosheets. The incorporation of the nanostructure into a PU/Cur-SC4A-LDH film provided bacteria-killing performance against both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli bacteria. This finding is due to an increase in curcumin bioavailability in the PU matrix. Furthermore, all PU nanocomposites exhibited appropriate cytocompatibility based on an MTT assay. Mainly, the proliferation of L929 fibroblast cells in contact with the PU/Cur-SC4A-LDH sample was significantly further enhanced than that for other nanocomposites within 7 days. This observation can be related to the better availability of curcumin on the film's surface, which causes an improvement in the proliferation rate of cells. Regarding the histological results, the hematoxylin and eosin (H&E) images showed faster epidermal layer formation and a larger quantity of matured hair follicles for PU/Cur-SC4A-LDH-healed wounds in comparison with those for the negative control over a period of 28 days. Thus, this practical healing ability of the PU/Cur-SC4A-LDH nanocomposite makes it a promising candidate as a wound dressing film.

Nonedible Vegetable Oil-Based Polyols in Anticorrosive and Antimicrobial Polyurethane Coatings

This review describes the preparation of nonedible vegetable oil (NEVO)-based polyols and their application in anticorrosive and antimicrobial polyurethane (PU) coatings. PUs are a class of versatile polymers made up of polyols and isocyanates. Renewable vegetable oils are promising resources for the development of ecofriendly polyols and the corresponding PUs. Researchers are interested in NEVOs because they provide an alternative to critical global food issues. The cultivation of plant resources for NEVOs can also be popularized globally by utilizing marginal land or wastelands. Polyols can be prepared from NEVOs following different conversion routes, including esterification, etherification, amidation, ozonolysis, hydrogenation, hydroformylation, thio-ene, acrylation, and epoxidation. These polyols can be incorporated into the PU network for coating applications. Metal surface corrosion and microbial growth are severe problems that cause enormous economic losses annually. These problems can be overcome by NEVO-based PU coatings, incorporating functional ingredients such as corrosion inhibitors and antimicrobial agents. The preferred coatings have great potential in high performance, smart, and functional applications, including in biomedical fields, to cope with emerging threats such as COVID-19.

Antibacterial and Biocompatible Hydrogel Dressing Based on Gelatin- and Castor-Oil-Derived Biocidal Agent

Favored antibacterial activity associated with excellent biocompatibility, mechanical durability, and exudate handling needs to be addressed by modern dressing to achieve the desired wound healing. This paper deals with developing a new green and facile approach to manufacturing nonleachable antibacterial gelatin-based films for wound dressing. Therefore, a reactive methoxy-silane-functionalized quaternary ammonium compound bearing a fatty amide residue originating from castor oil (Si-CAQ) was initially synthesized. The antibacterial dressings were then fabricated via sol-gel and condensation reactions of the mixture containing gelatin, Si-CAQ, (3-glycidyloxypropyl) trimethoxysilane, and poly(vinyl alcohol). By utilizing bioactive polymers as starting materials and eliminating organic solvents during the dressing preparation, desirable clinical safety could be ensured. The gelatin-based films presented appropriate mechanical properties, such as flexibility and strength, in both dried and hydrated states (tensile strength >6 MPa and elongation >100). It is due to the in situ generations of the inorganic silicon domain in the organic framework via the sol-gel cross-linking process. The prepared dressings exhibited desirable features, including excellent biocompatibility (cell viability >95%), proper wound-exudate-managing characteristics (equilibrium water contact (EWA) 280-350% and water vapor transmission rate (WVTR) 2040-2200 g/m²/day), fluid handling capacity (FHC) (3-3.35 g), as well as commendable hemocompatibility. The promising bactericidal activity of the dressing against Bacillus subtilis, methicillin-resistant Staphylococcus aureus, and Escherichia coli strains with a contact-killing efficacy of 100% could prevent infection development at the wounded area. As evaluated by the wound scratch assay, the desired fibroblast cell growth, migration, and proliferation indicated the capability of the dressing to facilitate the healing process by encouraging fibroblast cell migration to the damaged area. In vivo wound-healing results showed that the prepared biocidal dressing stimulates wound healing and enhances epithelialization, collagen maturation, and vascularization of wounds due to their antibacterial effects and accelerated cellular functions.

Therapeutic potential of castor oil in managing blepharitis, meibomian gland dysfunction and dry eye

The multifactorial pathogenesis and interrelationship of blepharitis, meibomian gland dysfunction and dry eye disease poses challenges to any therapeutic approach. Current treatments are mostly palliative, with success limited by perceived inefficacy and poor patient compliance. Castor oil, a natural derivative of the Ricinus communis plant, is widely used as an emollient in cosmetics and personal care products, drug delivery systems and wound dressings. Castor oil is deemed safe and tolerable, with strong anti-microbial, anti-inflammatory, anti-nociceptive, analgesic, antioxidant, wound healing and vaso-constrictive properties. Its main constituent, ricinoleic acid, has a bipolar molecular structure that promotes the formation of esters, amides and polymers. These can supplement deficient physiological tear film lipids, enabling enhanced lipid spreading characteristics and reducing aqueous tear evaporation. Studies reveal that castor oil applied topically to the ocular surface has a prolonged residence time, facilitating increased tear film lipid layer thickness, stability, improved ocular surface staining and symptoms. This review summarises the properties, current uses of, and therapeutic potential of castor oil in managing ocular surface disease. The biochemical, medicinal actions of castor oil are explored from the perspective of ocular surface pathology, and include microbial and demodectic over-colonisation, inflammatory and oxidative processes, as well as clinical signs and symptoms of dryness and discomfort.

Polymers and Composites Derived from Castor Oil as Sustainable Materials and Degradable Biomaterials: Current Status and Emerging Trends

Recent years have seen rapid growth in utilizing vegetable oils to derive a wide variety of polymers to replace petroleum-based polymers for minimizing environmental impact. Nonedible castor oil (CO) can be extracted from castor plants that grow easily, even in an arid land. CO is a promising source for developing several polymers such as polyurethanes, polyesters, polyamides, and epoxy-polymers. Several synthesis routes have been developed, and distinct properties of polymers have been studied for industrial applications. Furthermore, fillers and fibers, including nanomaterials, have been incorporated in these polymers for enhancing their physical, thermal, and mechanical properties. This review highlights the development of CO-based polymers and their composites with attractive properties for industrial and biomedical applications. Recent advancements in CO-based polymers and their composites are presented along with a discussion on future opportunities for further developments in diverse applications.

Enhanced healing of a full-thickness wound by a thermoresponsive dressing utilized for simultaneous transfer and protection of adipose-derived mesenchymal stem cells sheet

To boost the healing process in a full-thickness wound, a simple and efficient strategy based on adipose-derived mesenchymal stem cells (ADSCs) transplantation is described in this work. To increase the chance of ADSCs immobilization in the wound bed and prevent its migration, these cells are fully grown on the surface of a thermoresponsive dressing membrane under in vitro condition. Then, the cells sheet with their secreted extracellular matrix (ECM) is transferred to the damaged skin with the help of this dressing membrane. This membrane remains on wound bed and acts both as a cell sheet transfer vehicle, after external reduction of temperature, and protect wound during the healing process like a common wound dressing. The visual inspection of wounded skin (rat animal model) at selected time intervals shows a higher wound closure rate for ADSCs treated group. For this group of rats, the better quality of reconstructed tissue is approved by results of histological and immunohistochemical analysis since the higher length of the new epidermis, the higher thickness of re-epithelialization layer, a higher level of neovascularization and capillary density, and the least collagen deposition are detected in the healed tissue.

Biological applications study of bio-nanocomposites based on chitosan/TiO2 nanoparticles polymeric films modified by oleic acid

The aim of the present study was to prepare and characterize nanocomposite films to improve the treatment of skin wounds by applying the film as a bandage. To modify chitosan (Cs) and to prepare nanocomposites, a mixture between titanium dioxide nanoparticles (TiO₂ NPs) was performed at different concentrations (2, 5, 10 and 15 wt%) and oleic acid (OA). The thin nanocomposite films were prepared by using casting method. The prepared films (Cs, Cs/TiO₂ NPs, Cs/OA and Cs/OA/TiO₂ NPs) were described by water absorption (swelling study) and biological degradation. Physico-chemical characterizations of Cs, Cs/OA, Cs/TiO₂ NPs and Cs/OA/TiO₂ NPs (with only 15 wt% TiO₂ NPs) films were determined by X-ray diffraction, transmission high-resolution electron microscopy, field emission scanning electron microscopy, thermal analysis and Fourier transform infrared spectroscopy as well as their mechanical properties. Antimicrobial activity against microorganisms has been studied to assess activity against bacteria. The prepared nanocomposite films showed good antimicrobial activity for both Gram-positive and Gram-negative bacteria. The therapeutic effects of Cs-TiO₂ NPs-oleic acid nanocomposites on healing excision wounds were studied in rat animal model. The data obtained revealed that groups treated with nanocomposites showed enhancement wound closure and speed up wound healing time.

Assessment of the Efficacy of Tributylammonium Alginate Surface-Modified Polyurethane as an Antibacterial Elastomeric Wound Dressing for both Noninfected and Infected Full-Thickness Wounds

Risk factors of nonhealing wounds include persistent bacterial infections and rapid onset of dehydration; therefore, wound dressings should be used to accelerate the healing process by helping to disinfect the wound bed and provide moisture. Herein, we introduce a transparent tributylammonium alginate surface-modified cationic polyurethane (CPU) wound dressing, which is appropriate for full-thickness wounds. We studied the physicochemical properties of the dressing using Fourier transform infrared, ¹H NMR, and ¹³C NMR spectroscopies and scanning electron microscopy, energy-dispersive X-ray, and thermomechanical analyses. The surface-modified polyurethane demonstrated improved hydrophilicity and tensile Young's modulus that approximated natural skin, which was in the range of 1.5-3 MPa. Cell viability and in vitro wound closure, assessed by MTS and the scratch assay, confirmed that the dressing was cytocompatible and possessed fibroblast migratory-promoting activity. The surface-modified CPU had up to 100% antibacterial activity against Staphylococcus aureus and Escherichia coli as Gram-positive and Gram-negative bacteria, respectively. In vivo assessments of both noninfected and infected wounds revealed that the surface-modified CPU dressing resulted in a faster healing rate because it reduced the persistent inflammatory phase, enhanced collagen deposition, and improved the formation of mature blood vessels when compared with CPU and commercial Tegaderm wound dressing.

Ionic liquid tethered PEG-based polyurethane-siloxane membranes for efficient CO2/CH4 separation

This study introduces a new polyethylene glycol (PEG) based polyurethane-siloxane membrane containing a quaternary ammonium ionic liquid for CO₂/CH₄ separation. The designed ionic liquid was prepared in two steps: (i) (3-chloropropyl)triethoxysilane (CPS) and N,N-dimethylpropyl amine (NDPA) were reacted with each other to form the methoxysilane-functionalized quaternary ammonium component, then (ii) chloride ion (Cl^-) of the product was exchanged with tetrafluoroborate ion (BF₄^-). The resulting compound, a reactive methoxysilane-functionalized ionic liquid (Si-IL) was chemically anchored to the polymer backbone through the sol-gel hydrolysis and condensation reaction. Based on the permeation tests, the IL containing PEG-based polyurethane-siloxane membranes at different concentration of Si-IL (XSi-PPUIL) were found to be potential candidates for CO₂ removal from CH₄. For instance, the CO₂/CH₄ selectivity of XSi-PPUIL membranes with the Si-IL content of 10 wt% was 3.3-fold greater than the Si-IL free membranes; while, the CO₂ permeability for IL tethered membranes was 9.7% higher than the corresponding IL-free membrane.

Antimicrobial wound dressings with high mechanical conformability prepared through thiol-yne click photopolymerization reaction

Radical mediated photochemical thiol-yne click polymerization of thiol-terminated polyurethane prepolymers, with poly(ethylene glycol) soft segment at two different molecular weights, a propargyl terminated urethane crosslinker and silver salt was utilized to prepare versatile wound dressings containing well-dispersed Ag° nanoparticles produced via in situ reduction of Ag⁺ ions. The dressings with optimized chemical structure showed desirable fluid handling capacity (up to 4.84 g/10 cm² d^-1) to provide moist environment over damaged tissue. They were permeable to oxygen and carbon dioxide, therefore, the processes related to tissue regeneration of wound bed could be continued without problem. Their appropriate tensile strength (up to 3.87 MPa) and suitable conformability (less than 0.1% permanent set) enabled protection of damaged skin tissue from external physical forces during the healing process, even for wounds present at organs with a high degree of freedom. The proper cytocompatibility of the prepared dressings and their ability to support growth and proliferation of fibroblast cells as determined by wound scratch healing assay showed the potential utility of the dressings to motivate wound healing progression by migration of cells to the damaged area. In addition, these dressings with in situ formed silver nanoparticles exhibited promising antimicrobial activity against different bacterial and fungal strains, and consequently could encourage wound healing process by prevention from infection in the wound site.

Silver triethanolamine-loaded PVB/CO films for a potential liquid bandage application

Many studies have reported that silver has excellent antibacterial properties. However, silver ions can easily react with oxygen to form Ag2O, thus leading to a color change and a reduction in its anti-microbial characteristics. In this study, silver triethanolamine- (ST) loaded PVB/CO solution was prepared as a potential candidate liquid bandage. PVB/CO/ST retained high transparency after exposure to light for 12 months, which allowed convenient inspection of the wound bed without removal of the dressing. The PVB/CO/ST film exhibited favorable properties, such as speed of drying, excellent tensile strength and elongation characteristics and water vapor transmission rate (WVTR). It was comfortable and waterproof, and therefore effective at preventing bacterial invasion, providing effective biosafety. PVB/CO/ST solution-treated wounds exhibited accelerated healing and reduced inflammation in a nude mouse mode. Our data suggested that PVB/CO/ST solution could serve as a promising liquid bandage for treatment of minor trauma.

Castor oil: a suitable green source of capping agent for nanoparticle syntheses and facile surface functionalization

Castor oil (CO) is an inedible vegetable oil (VO) that has been employed extensively as a bioresource material for the synthesis of biodegradable polymers, cosmetics, lubricants, biofuels, coatings and adhesives. It is used in medicine, pharmaceuticals and biorefineries, due to its versatile chemistry. However, there has been less focus on CO as an alternative to toxic and expensive solvents, and capping/stabilizing agents routinely used in nanoparticle syntheses. It provides a richer chemistry than edible VOs as a solvent for green syntheses of nanoparticles. CO, being the only rich source of ricinoleic acid (RA), has been used as a solvent, co-solvent, stabilizing agent and polyol for the formation of polymer-nanoparticle composites. RA is a suitable alternative to oleic acid used as a capping and/or stabilizing agent. Unlike oleic acid, it provides a facile route to the functionalization of surfaces of nanoparticles and the coating of nanoparticles with polymers. For applications requiring more polar organic solvents, RA is more preferred than oleic acid. In this review, we discuss the production, chemical and physical properties, triglyceride and fatty acid (FA) compositions and applications of CO, focusing on the use of CO and RA as well as other VOs and FAs in syntheses of nanoparticles and surface functionalization.

Polyurethane/siloxane membranes containing graphene oxide nanoplatelets as antimicrobial wound dressings: in vitro and in vivo evaluations

Preserving wounds from bacterial and fungal infections and retaining optimum moist environment over damaged tissue are major challenges in wound care management. Application of wound dressings with antimicrobial activity and appropriate wound exudates handling ability is of particular significance for promoting wound healing. To this end, preparation and evaluation of novel wound dres1sings made from polyurethane/siloxane network containing graphene oxide (GO) nanoplatelets are described. The particular sol-gel hydrolysis/condensation procedure applied for the preparation of dressings leads to an appropriate distribution of GO nanoplatelets in the dressing membranes. The crosslinked siloxane domains and the presence of GO nanoplatelets within polymeric chains offered necessary mechanical strength for dressings. Meanwhile, a combination of hydrophilic and hydrophobic moieties in dressing backbone enabled suitable wound exudate management. Therefore, both of physical protection from external forces and preservation of moist environment over wound were attained by using the designed dressings. Widespread antimicrobial activity against gram-positive, gram-negative and fungal strains was recorded for the dressing with the optimum amount of GO, meanwhile, very good cytocompatibility against fibroblast cells was noted for these dressings. In vivo assay of the GO containing dressing on rat animal model reveals that the dressing can promote wound healing by complete re-epithelization, enhanced vascularization and collagen deposition on healed tissue.

Hyperbranched polyesters as biodegradable and antibacterial additives

Herein, we present novel hyperbranched poly(amino-ester)s functionalized with quaternary ammonium salts.

The use of medicinal herbs in gynecological and pregnancy-related disorders by Jordanian women: a review of folkloric practice vs. evidence-based pharmacology

Context National statistical reports in Jordan indicate a decrease in the total fertility rate along with a parallel increase in contraceptive use. The folkloric use of medicinal herbs in gynecological disorders has been growing in Jordan, despite of deficient reports on the evidence-based safety and efficacy of these practices. Objective The aim of this comprehensive article is to review medicinal plants with claimed ethnonpharmacological usage in various gynecological and pregnancy-related issues in Jordan, and to assess their evidence-based pharmacological studies as well as their phytochemistry. Methods The published literature was surveyed using Google Scholar entering the terms "ethnopharmacology AND Jordan AND infertility AND gynecology OR gestation". We included ethnopharmacological surveys in Jordan with available full-text. Results Twelve articles were reviewed. Plant species which are commonly used for female gynecological issues such as Artemisia monosperma Del. and A. herba-alba Asso. (Asteraceae) have been found to exert an antifertility effect. Ricinus communis L. (Euphorbiaceae) and Citrullus colocynthis (L.) Schrad. (Cucurbitaceae) had antifertility effects in male rats, but Nigella sativa oil L. (Ranunculaceae) and Cinnamon zeylanicum J. Presl (Lauraceae) were found to enhance it. Conclusion Using plants for gynecological disorders is a common practice in Jordan. Many of them, whether utilised for gynecological or non-gynecological conditions equally, were found to have detrimental effects on female or male fertility. Thus, couples planning pregnancy should be discouraged from the consumption of these herbs. Further local studies are warranted to confirm the appreciable beneficial pharmacological effects and safety of these plants.

Thermoresponsive polyurethane/siloxane membrane for wound dressing and cell sheet transplantation: In-vitro and in-vivo studies

Polyurethane/siloxane based wound dressing for transferring fibroblast cell sheet to wounded skin and ability to provide an optimum condition for cellular activity at damaged tissue was prepared in this research. The dressing was made thermoresponsive, via the introduction of a poly(N-isopropyl acrylamide) copolymer into the backbone of dressing. The ability of membrane for adhesion, growth, and proliferation of fibroblast cells was improved via surface modification with gelatin. The optimized dressing exhibited appropriate tensile strength (4.5MPa) and elongation at break (80%) to protect wound against physical forces. Due to controlled equilibrium water absorption of about 89% and water vapor transmission rate of 2040g/m(2)day, the dressing could maintain the favorable moist environment over moderate to high exuding wounds. The grown cell sheet on dressing membrane could easily roll up from the surface just with lowering the temperature. The in vivo study of the wound dressed with cell loaded membrane confirmed the accelerated healing and production of tissue with complete re-epithelization, enhanced vascularization, and increased collagen deposition on the damaged area.

Dendrons as active clicking tool for generating non-leaching antibacterial materials

Dendrons with a focal point and quaternary ammonium peripheral groups are tools for making non-active polymers and surfaces antibacterial.

Stimulation of Wound Healing by Electroactive, Antibacterial, and Antioxidant Polyurethane/Siloxane Dressing Membranes: In Vitro and in Vivo Evaluations

A series of novel polyurethane/siloxane-based wound dressing membranes was prepared through sol-gel reaction of methoxysilane end-functionalized urethane prepolymers composed of castor oil and ricinoleic methyl ester as well as methoxysilane functional aniline tetramer (AT) moieties. The samples were fully characterized and their physicochemical, mechanical, electrical, and biological properties were assayed. The biological activity of these dressings against fibroblast cells and couple of microbes was also studied. It was revealed that samples that displayed electroactivity by introduction of AT moieties showed a broad range of antimicrobial activity toward different microorganisms, promising antioxidant (radical scavenging) efficiency and significant activity for stimulation of fibroblast cell growth and proliferation. Meanwhile, these samples showed appropriate tensile strength and ability for maintaining a moist environment over a wound by controlled equilibrium water absorption and water vapor transmission rate. The selected electroactive dressing was subjected to an in vivo assay using a rat animal model and the wound healing process was monitored and compared with analogous dressing without AT moieties. The recorded results showed that the electroactive dressings induced an increase in the rate of wound contraction, promoted collagen deposition, and encouraged vascularization in the wounded area. On the basis of the results of in vitro and in vivo assays, the positive influence of designed dressings for accelerated healing of a wound model was confirmed.

Wound Healing Bionanocomposites Based on Castor Oil Polymeric Films Reinforced with Chitosan-Modified ZnO Nanoparticles

Castor oil (CO), which is a readily available, relatively inexpensive, and environmentally benign nonedible oil, has been successfully used as matrix material to prepare biocompatible and biodegradable nanocomposite films filled with chitosan (CS)-modified ZnO nanoparticles. The biocomposites were synthesized via a simple and versatile solution mixing and casting method. The morphology, structure, thermal stability, water absorption, biodegradability, cytocompatibility, barrier, mechanical, viscoelastic, antibacterial, and wound healing properties of the films have been analyzed. FT-IR spectra were used to obtain information about the nanoparticle-matrix interactions. The thermal stability, hydrophilicity, degree of porosity, water absorption, water vapor transmission rate (WVTR), oxygen permeability (Dk), and biodegradability of the films increased with the CS-ZnO loading. The WVTR and Dk data obtained are within the range of values reported for commercial wound dressings. Tensile tests demonstrated that the nanocomposites displayed a good balance between elasticity, strength, and flexibility under both dry and simulated body fluid (SBF) environments. The flexibility increased in a moist atmosphere due to the plasticization effect of absorbed water. The nanocomposites also exhibited significantly enhanced dynamic mechanical performance (storage modulus and glass transition temperature) than neat CO under different humidity conditions. The antibacterial activity of the films against Escherichia coli, Staphylococcus aureus, and Micrococcus luteus bacteria was investigated in the presence and the absence of UV light. The biocide effect increased progressively with the CS-ZnO content and was systematically stronger against Gram-positive cells. Composites with nanoparticle loading ≤5.0 wt % exhibited very good in vitro cytocompatibility and enabled a faster wound healing than neat CO and control gauze, hence showing great potential to be applied as antibacterial wound dressings.

Assessments of antibacterial and physico-mechanical properties for dental materials with chemically anchored quaternary ammonium moieties: thiol-ene-methacrylate vs. conventional methacrylate system

OBJECTIVE

Fabrication of low shrinkage stress and strain dental resins containing highly available immobilized bactericidal moieties has been reported. The goal of this study is producing dental restorative materials with long-last antibacterial activity and reduced secondary caries. It is anticipated that antibacterial properties of quaternary ammonium moieties chemically immobilized in the backbone of dental resins is directly depended on accessibility of these functions. In the present study the antibacterial effect of a series of antibacterial monomers polymerized in a ternary thiol-ene-methacrylate system were compared with corresponding classical methacrylate system against Streptococcus mutans (an oral bacteria Strain). Physical and mechanical properties of dental materials obtained from these two systems were also evaluated and compared.

METHODS

The viscosities of the resin matrixes were measured on a MCR 300 rheometer. Degree of conversion (DC%) of monomers was measured using FTIR spectroscopy. The shrinkage-strain of photocured resins was measured using the bonded-disk technique. A universal testing machine combined with a stress measurement device was utilized to measure the polymerization-induced shrinkage stress. Viscoelastic properties of the samples were also determined by dynamic mechanical thermal analysis (DMTA). Assessment of antibacterial properties was performed through agar diffusion test (AD) to confirm non-release behavior of chemically anchored moieties. Quantitative assay of antibacterial activity was evaluated through direct contact test (DCT) against S. mutans. Direct contact cytotoxicity assay with fibroblast cell line L-929 was also performed to find more insight regarding cytotoxicity of the antibacterial matrixes. The data were analyzed and compared by ANOVA and Tukey HSD tests (significance level=0.05).

RESULTS

Neat methacrylate systems had significantly higher viscosity than thiol-ene-methacrylate analogous. The degree of conversion of methacrylate moieties in thiol-ene-methacrylate system was improved in comparison to conventional methacrylate system. Shrinkage stress and strain of thiol-ene-methacrylate system was lower than the neat methacrylate system. The thiol-ene-methacrylate systems show increased homogeneity and decreased glass transition temperature (Tg) and crosslink density (νc) in comparison to the neat methacrylate-based resins. The incorporated monofuctional quaternized monomer reduces degree of conversion, shrinkage stress and crosslink density of matrix. The results showed significant improvement in antibacterial activity and cytocompatibility of dental materials obtained from thiol-ene polymerization system.

SIGNIFICANCE

It was shown that with proper control of monomers molar ratio, significant improvement in antibacterial activity and cytocompatibility as well as acceptable mechanical properties can be attained for dental resins prepared through the application of thiol-ene polymerization methodology.

Thermoresponsive antimicrobial wound dressings via simultaneous thiol-ene polymerization and in situ generation of silver nanoparticles

Thermoresponsive and antimicrobial wound dressing via thiol-ene polymerization reaction.

Epoxidized soybean oil/ZnO biocomposites for soft tissue applications: preparation and characterization

Biocompatible and biodegradable nanocomposites comprising epoxidized soybean oil (ESO) as matrix, zinc oxide (ZnO) nanoparticles as reinforcements, and 4-dimethylaminopyridine (DMAP) as a catalyst have been successfully prepared via epoxidization of the double bonds of the vegetable oil, ultrasonication, and curing without the need for interfacial modifiers. Their morphology, water uptake, thermal, mechanical, barrier, tribological, and antibacterial properties have been investigated. FT-IR analysis revealed the existence of strong ESO-ZnO hydrogen-bonding interactions. The nanoparticles acted as mass transport barriers, hindering the diffusion of volatiles generated during the decomposition process and leading to higher thermal stability, and also reduced the water absorption and gas permeability of the bioresin. Significant improvements in the static and dynamic mechanical properties, such as storage and Young's moduli, tensile strength, toughness, hardness, glass transition, and heat distortion temperature, were attained on reinforcement. A small drop in the nanocomposite stiffness and strength was found after exposure to several cycles of steam sterilization or to simulated body fluid (SBF) at physiological temperature. Extraordinary reductions in the coefficient of friction and wear rate were detected under both dry and SBF conditions, confirming the potential of these nanoparticles for improving the tribological performance of ESO. The nanocomposites displayed antimicrobial action against human pathogen bacteria with and without UV illumination, which increased progressively with the ZnO content. These sustainable, ecofriendly, and low-cost biomaterials are very promising for use in biomedical applications, like structural tissue engineering scaffolds.

The influence of applied silica nanoparticles on a bio-renewable castor oil based polyurethane nanocomposite and its physicochemical properties

Bio-renewable castor oil polyurethane–silica nanocomposite films with improved thermal, surface and mechanical properties were prepared. These films find application in biomaterials development.