Hydrogels based on poly(methacrylic acid) and nanocellulose with potential application in dental treatments

pH sensitive hydrogels, such as hydrogels based on poly(methacrylic acid) (PMAA), are tremendous materials with great properties due to which they have application in many fields, such as: targeted drug delivery, tissue engineering, as contact lenses etc. Hydrogels based on PMAA are non-toxic, biocompatible and able to absorb and retain huge amount of water. These hydrogels are widely used for targeted drug delivery due to their specific pH swelling behavior which enable drug release in environments with pH values higher than pKa(PMAA). However, poor mechanical properties of hydrogels based on PMAA often limit their application. In order to overcome this limitation, green approach is used in present study. Namely, nanocellulose (NC) extracted from wood waste material is added to PMAA due to NC non-toxicity, biocompatibility, biodegradability and great mechanical properties (which is used for improvement of hydrogels mechanical characteristics). Further improvement of hydrogels based on PMAA and NC is achieved by adding carboxymethyl cellulose (CMC). CMC is non-toxic, biocompatible, biodegradable, pH-sensitive derivate of cellulose widely used in drug delivery systems. Drug delivery system prepared in that way can enable controlled release of drug (such as lidocaine hydrochloride (Lid)) for prolonged period of time and therefore, reduce the number of acquired drug dosages which further lead to safe and efficient drug application. Therefore, Lid is encapsulated in hydrogels based on PMAA, NC and CMC (PM/NC-Lid). Lid is local anesthetic often used in dental treatment and it is usually administrated by injection, which is painful, unpleasant and treatment is often required several dosages. These limitations can be overcome by applying PM/NC-Lid hydrogels as buccal patches for controlled release of lidocaine hydrochloride. Present study describes green synthesis and characterization of PM/NC-Lid hydrogels (using the Fourier Transform Infrared spectroscopy (FT-IR), the Scanning Electron Microscopy (SEM) and the single compression tests). Also, PM/NC-Lid swelling behavior and Lid controlled release from PM/NC-Lid hydrogels is investigated depending on the variable synthesis parameter (NC wt%) in simulated buccal environment. Results presented in this study show that PM/NC-Lid hydrogels are promising materials for controlled release of anesthetic drugs and for potential application as buccal patches in dental treatments

Effect of neutralization degree of methacrylic acid on hydrogel swelling and drug release

Drug delivery system is an amazing tool which is widely used for drug protection and its controlled release in order to enhance drug bioavailability, reduce side effects and therefore to improve overall therapy. Hydrogels have been attracted great attention as drug carriers due to their great physicochemical properties, similarity to the living tissues and biocompatibility. One group of pH sensitive hydrogels are based on poly(methacrylic acid) (PMAA). These non-toxic hydrogels are used as drug delivery system because they swell as a response to the change in pH of external environment and drug is being released during the process. In present study, in order to improve the control of drug release rate, caffeine was encapsulated in liposomes which were further embedded into PMC hydrogel (PMCL). It was investigated how the change in neutralization degree of methacrylic acid affect the swelling degree of PMCL hydrogels and caffeine release in two environments at 37 °C for 24 h: 0.1 M hydrochloride acid (pH 1) and phosphate buffer with pH value of 6.8 (pH 6.8), as a simulation of pH environment in human stomach and intestines, respectively. Obtained results show that PMCL hydrogels have great potential for controlled release of poorly water-soluble drugs in human intestines

Modification of hydrophilic polymer network to design a carrier for a poorly water-soluble substance

pH sensitive, nontoxic, and biocompatible poly(methacrylic) acid (PMAA) based soft networks have been extensively used in the design of systems for targeted drug delivery. Still, their highly hydrophilic nature limits their potential to be used as a carrier of poorly water-soluble substances. With the aim to overcome this limitation, the present study details a new approach for modification of PMAA based carriers using two amphiphilic components: casein and liposomes. The FTIR analysis revealed structural features of each component as well as the synergetic effect that originated from the formation of specific interactions. Namely, hydrophobic interactions between the poorly water-soluble model drug (caffeine) and casein enabled caffeine encapsulation and controlled release, while addition of liposomes ensured better control of the release rate. The morphological properties of the carriers, swelling behavior, and release kinetics of caffeine were investigated depending on the variable synthesis parameters (neutralization degree of methacrylic acid, concentration of caffeine, presence/absence of liposomes) in two different media simulating the pH environment of human intestines and stomach. The data obtained from in vitro caffeine release were correlated and analyzed in detail using several mathematical models, indicating significant potential of investigated carriers for targeted delivery and controlled release of poorly water-soluble substances

Methacrylic Acid Based Polymer Networks with a High Content of Unfunctionalized Nanosilica: Particle Distribution, Swelling, and Rheological Properties

The poor stability and tendency to agglomerate of unfunctionalized nano-SiO₂ in the presence of ionic species presents a challenge for preparing poly­(methacrylic acid)/nano-SiO₂ nanocomposite (NC) hydrogels with desired strength and swelling capability. We proposed a facile and eco-friendly method for the preparation of PMAA/SiO₂ NC hydrogels using unfunctionalized silica nanoparticles (NPs) in the form of a suspension. SEM and TEM analyses showed that the NP distribution in the polymer matrix highly depended on the particle concentration. At lower concentrations (up to 13.9 wt %), the NPs were uniformly dispersed as single nanoparticles. With an increase in NP concentration, homogeneously dispersed nanoscale aggregates were formed, while a further increase in the silica concentration led to the formation of homogeneous structures consisting of mutually interacting nanosilica particles coated with PMAA. Swelling experiments confirmed that the silica NPs behaved as adhesive fillers that interacted with PMAA chains, causing the formation of a thin polymer layer strongly adsorbed at the particle interface. The thicknesses of the adsorbed polymer layer, as well as the swelling kinetic parameters, were strongly influenced by nanoparticle size and concentration. Combining nanosilica and PMAA in the form of a soft hydrogel network provided stabilization of the NPs and ensured better mechanical properties of the obtained NC hydrogels compared to pure polymer matrix. The optimal loadings, necessary to ensure the most improved dynamical-mechanical properties, were found in the case of the formation of homogeneously dispersed, nanosized silica aggregates in a PMAA matrix

Synthesis and characterization of fully bio-based unsaturated polyester resins

The sustainable tomorrow for future generations lies with the present industrial development toward the proper utilization of various bio-based products. For a transition to a higher level of sustainability, it is necessary to form a new platform for advanced technology products. This paper reports the development of new fully bio-based unsaturated polyesters resins (UPRs). A series of prepolymers were synthesized by varying saturated diacids (oxalic, succinic and adipic acid), itaconic acid and 1,2-propandiol. Dimethyl itaconate was used as a reactive diluent (RD) in amounts of 30, 35 and 40 wt%. Rheological measurements showed that the obtained resins possessed viscosities (234-2226 mPa s) amenable to a variety of liquid molding techniques. The impact of composition variables-prepolymer structure and amount of RD-on the chemical, mechanical and thermal properties of the thermosets was examined by DMA, TA and tensile measurements and was discussed in detail. The tensile properties (37-52 MPa), glass transition temperature (60-97 A degrees C) and coefficient of thermal expansion (71-168 10(-6) A degrees C-1) of the cured resins were in the desired range for UPRs. This investigation showed that UPRs based on itaconic acid can be tailored during synthesis of the prepolymer to meet the needs of different property profiles

Methacrylic Acid Based Polymer Networks with a High Content of Unfunctionalized Nanosilica: Particle Distribution, Swelling, and Rheological Properties

The poor stability and tendency to agglomerate of unfunctionalized nano-SiO2 in the presence of ionic species presents a challenge for preparing poly(methacrylic acid)/nano-SiO2 nanocomposite (NC) hydrogels with desired strength and swelling capability. We proposed a facile and eco-friendly method for the preparation of PMAA/SiO2 NC hydrogels using unfunctionalized silica nanoparticles (NPs) in the form of a suspension. SEM and TEM analyses showed that the NP distribution in the polymer matrix highly depended on the particle concentration. At lower concentrations (up to 13.9 wt %), the NPs were uniformly dispersed as single nanoparticles. With an increase in NP concentration, homogeneously dispersed nanoscale aggregates were formed, while a further increase in the silica concentration led to the formation of homogeneous structures consisting of mutually interacting nanosilica particles coated with PMAA. Swelling experiments confirmed that the silica NPs behaved as adhesive fillers that interacted with PMAA chains, causing the formation of a thin polymer layer strongly adsorbed at the particle interface. The thicknesses of the adsorbed polymer layer, as well as the swelling kinetic parameters, were strongly influenced by nanoparticle size and concentration. Combining nanosilica and PMAA in the form of a soft hydrogel network provided stabilization of the NPs and ensured better mechanical properties of the obtained NC hydrogels compared to pure polymer matrix. The optimal loadings, necessary to ensure the most improved dynamical-mechanical properties, were found in the case of the formation of homogeneously dispersed, nanosized silica aggregates in a PMAA matrix