Towards bioactive containing restorative materials: from design to testing in vitro approach

In any repair of a tooth with permanent restorative materials, the interface is always a sensitive region. The appearance of adhesive materials was a great step forward in dealing with the problems of this region and improving the overall performance of the restorations. However, contemporary adhesive materials do have a major disadvantage, namely that their durability is limited, a limitation which often arises due to their inadequate marginal adaptation. Restorative materials in the new era aim to be “bio-active” and long lasting. As part of our continuous interest in developing the novel bioactive containing restorative materials, we evaluated the effect of the additional bio-actives (such as chitosan, β-carotene, guar gum resin and the combination of the materials) to the commercially available flowable restorative materials such as Premise on the volumetric shrinkage, flexural strength, compressive strength, the surface hardness of the “bio-active” containing composit

Insights into chitosan hydrogels on dentine bond strength and cytotoxicity

Contemporary dental adhesives show favorable im- mediate results in terms of bonding effectiveness. However, the durability of resin-dentin bonds is their major problem. Materials and Methods: Preparation of 3 chitosan-antioxidant hydrogels was achieved us- ing modified hydrogel preparation method. Their effect on the bond strength to dentine both short term (after 24 hours) and long term (after 6 months) were evaluated using shear bond strength measurements using Instron Universal Testing Mascine). The SEM was used to study the surface of the hydrogels. The cell survival rate (cytotoxicity) of the antioxidants re- sveratrol, β-carotene and propolis towards Balb/c 3T3 mouse fibroblast cells was also assessed using the standard MTT assay. Results: It was found that chi- tosan-H treated dentine gives significantly (p propolis (68%) > resveratrol (33%). Conclusion: the antioxidant-chitosan hydro- gels significantly improved bonding to dentine with or without phosphoric acid treatment. The pH of the growth medium had a high influence on the cell survival rate of Balb/c mouse 3T3 fibroblast cells. The release of the antioxidant β-carotene would not have an influence on the pulp cells. These materials might address the current perspectives for improving bond durability.DDF fund of the South African Dental Association; School of Dentistry and Oral Health, Griffith UniversityWeb of Scienc

Vinyl Ester Oligomer Crosslinked Porous Polymers Prepared via Surfactant-Free High Internal Phase Emulsions

Using vinyl ester resin (VER) containing styrene (or methyl methacrylate) and vinyl ester oligomer (VEO) as external phase, Pickering high internal phase emulsions (Pickering HIPEs) having internal phase volume fraction of up to 95 vol% were prepared with copolymer particles as sole stabilizer. Polymerizing the external phase of these Pickering HIPEs led to porous polymers (poly-Pickering-HIPEs). Compared to the polystyrene- (PS-) based poly-Pickering-HIPEs which were prepared with mixture of styrene and divinylbenzene (DVB) as crosslinker, the poly-Pickering-HIPEs herein showed much higher elastic modulus and toughness. The elastic modulus of these poly-Pickering-HIPEs increased with increasing the VEO concentration in the external phase, while it decreased with increasing internal phase volume fraction. Increasing VEO concentration in the external phase also resulted in a decrease in the average void diameter as well as a narrow void diameter distribution of the resulting poly-Pickering-HIPEs. In addition, there were many small pores in the voids surface caused by the volume contraction of VER during the polymerization, which suggests a new method to fabricate porous polymers having a well-defined hierarchical pore structure

Preparation and evaluation of PEGylated phospholipid membrane coated layered double hydroxide nanoparticles

AbstractThe aim of the present study was to develop layered double hydroxide (LDH) nanoparticles coated with PEGylated phospholipid membrane. By comparing the size distribution and zeta potential, the weight ratio of LDH to lipid materials which constitute the outside membrane was identified as 2:1. Transmission electron microscopy photographs confirmed the core-shell structure of PEGylated phospholipid membrane coated LDH (PEG-PLDH) nanoparticles, and cell cytotoxicity assay showed their good cell viability on Hela and BALB/C-3T3 cells over the concentration range from 0.5 to 50 μg/mL

Bio-Active Nano-Diamond Designer Materials and Dentures: From Design to Application

Objective: The present study aims to design functional biomaterials and evaluate performance of nano-diamond: chitosan based bio-active containing PMMA (polymethyl methacrylate) materials towards application in treatment and prevention of denture stomatitis and associated conditions in denture wearers. Methods: The bio-active nano-diamond modified PMMA were prepared by dispersion of the corresponding component in glycerol and acetic acid with the addition of chitosan gelling agent. The release behaviors at physiological pH and also under acidic conditions and stability of the antioxidant-chitosan-nano-diamond were also evaluated. Mechanical performance such as tensile strength and compressive strength were measured as well bio-adhesive studies were investigated in order to assess the suitability of these designer materials. Results: The bio-active nano-diamond modified PMMA materials showed a high adhesive force and they only swelled slightly in the aqueous medium. Bioactive release suggested prolonged release of the therapeutic agent from the hydrogels. The hydrogels also had significant free radical defense capability. Conclusion: In this study we demonstrated that the newly prepared bio-active modified PMMA resins are suitable novel bio-active materials capable of comparable performance with the conventional PMMA materials with additional benefit of therapeutic bioactive release as well as potential antimicrobial properties to be demonstrated in vitro. Our findings might be thus a step forward towards the development of alternative non antibiotic based strategies targeting bacterial infections

Temporomandibular Joint Dysfunctions and Bio-Materials: Design, Free Radical Defense and Mechanism In Vitro

The aim of this investigation is to evaluate the suitability and flexibility of the bio-active containing designer materials to act as an “in vitro” probe to gain insights into molecular origin of TMJ. The hydroxyapatite/chitosan containing hydrogels represent a reliable biocompatible scaffold and allowed to evaluate the defense “build in” free radical defense mechanism of the functionalized bio-scaffolds on the molecular level, compare the effectiveness of the designer materials with the earlier reported capabilities of N-acetyl cysteine and apply the newly developed materials for the evaluation of new therapeutic treatment modalities in the TMJ therapy in vitro. Materials and Methods: The hydrogels were prepared by dispersion of the corresponding component in glycerol and acetic acid with the addition of chitosan: hydroxyapatite as a molecular scaffold. The surface morphology (SEM), release behaviors (physiological pH and also in acidic conditions), stability of the antioxidant-chitosan were also evaluated. Structural investigations of the reactive surface of the hydrogel are reported. Bio-adhesive studies and mechanical properties of newly prepared materials were conducted to assess the suitability of these designer materials. Ability of the materials to release the phenolic components as potential therapeutic agents was assessed. Results: The sustained release of total phenolic component as a potential therapeutic agent confirms the added benefit of synergistic action of a functional therapeutic delivery when comparing the newly designed chitosan/HA-based hydrogel molecular scaffold. The hydrogel formulations have a uniform distribution of drug content. The bio-adhesive capacity, tensile strength, compressive strength as well as modulus of elasticity of the hydroxyapatite containing materials in the “in vitro” systems was tested and quantified. Conclusion: The added benefits of the chitosan hydroxyapatite treated hydrogels involved positive influence on the phenolic component release, sustainable bio-adhesion, tensile strength, compressive strength as well as modulus of elasticity of the hydroxyapatite containing materials in the “in vitro” systems was tested and demonstrated in vitro “build in” free radical defense mechanism

Miniature intravascular photoacoustic endoscopy with coaxial excitation and detection

Recent research pointed out that the degree of inflammation in the adventitia could correlate with the severity of atherosclerotic plaques. Intravascular photoacoustic endoscopy can provide the information of arterial morphology and plaque composition, and even detecting the inflammation. However, most reported work used a non-coaxial configuration for the photoacoustic catheter design, which formed a limited light-sound overlap area for imaging so as to miss the adventitia information. Here we developed a novel 0.9 mm-diameter intravascular photoacoustic catheter with coaxial excitation and detection to resolve the aforementioned issue. A miniature hollow ultrasound transducer with a 0.18 mm-diameter orifice in the center was successfully fabricated. To show the significance and merits of our design, phantom and ex vivo imaging experiments were conducted on both coaxial and non-coaxial catheters for comparison. The results demonstrated that the coaxial catheter exhibited much better photoacoustic/ultrasound imaging performance from the intima to the adventitia

A miniature multi-functional photoacoustic probe

Photoacoustic technology is a promising tool to provide morphological and functional information in biomedical research. To enhance the imaging efficiency, the reported photoacoustic probes have been designed coaxially involving complicated optical/acoustic prisms to bypass the opaque piezoelectric layer of ultrasound transducers, but this has led to bulky probes and has hindered the applications in limited space. Though the emergence of transparent piezoelectric materials helps to save effort on the coaxial design, the reported transparent ultrasound transducers were still bulky. In this work, a miniature photoacoustic probe with an outer diameter of 4 mm was developed, in which an acoustic stack was made with a combination of transparent piezoelectric material and a gradient-index lens as a backing layer. The transparent ultrasound transducer exhibited a high center frequency of ~47 MHz and a −6 dB bandwidth of 29.4%, which could be easily assembled with a pigtailed ferrule of a single-mode fiber. The multi-functional capability of the probe was successfully validated through experiments of fluid flow sensing and photoacoustic imaging

Towards Bio-active Restorative Materials with Copaiba Oil and Oblepicha Oil: In vitro

We developed and evaluated chitosan - fucoidan bio-composites with additional bioactive components of oblepicha oil and copaiba oil for bioactive restorative material as intra-dental and wound healing applications such as bioadhesion to soft and hard tissue in vitro, dentin bond strength and free radical defense mechanism for the compounds in the oral environment

Synthesis of Monodisperse Styrene/Methyl Methacrylate/Acrylic Acid Latex Using Surfactant-Free Emulsion Copolymerization in Air

International audienceMonodisperse styrene/methyl methacrylate/acrylic acid (St/MMA/AA) copolymer microspheres have been prepared with surfactant-free emulsion polymerization in air. The presence of oxygen in the system not only caused an induction period but also decreased the average particle size (D(p)). However increasing AA concentration ([AA]) gave a reduction in the induction period. The FTIR and NMR analysis of the latex copolymer confirmed that the correlation of the copolymer compositions with the feed compositions was much better at the lower [AA] than at the higher levels. The AA contents of the copolymers obtained in air were much lower than those of the copolymers obtained under N(2) protection. Decreasing [AA] led to decrease in the copolymer molecular weight and broadening of the molecular weight distribution, but the particle size distribution (delta/D(p)) was unaffected. In addition, the average particle diameter (D(p)) was proportional to [AA](-0-2.55), and increasing comonomers feed content caused linear increase of D(p), and a monodisperse sample with final solids contents up to 34.2 wt % was obtained