Search

Individually tailored drug delivery systems (DDSs) are considered one of the most promising therapeutic tools for the creation of safe and effective treatments. DDSs as a novel approach should be beneficial in curing systemic as well as local ailments, where a high topical concentration of the drug and a reduction of side effects are desirable. It could also be favorable for patients requiring customized treatments, showing atypical profiles of drug metabolism. Development of particular drug delivery devices require the selection of a suitable scaffold material, which should exhibit proper mechanical and biological properties, but also enable adjustment of the drug release according to a specific need. Thus, it is extremely important to expand the knowledge concerning potential DDS components. Poly(ethylene glycol) diacrylate (PEGDA) according to its properties can be easily used as a DDS resin and shaped into a desired structure with the employment of techniques based on photopolymerization, including some novel 3D printing techniques. As a continuation of our previous works, in this paper drug release studies from conventionally prepared PEGDA scaffolds are presented. We have shown that in PEGDA materials, the release profile of the low molecular weight model drug acetylsalicylic acid can be altered by water content. PEGDA as a delivery material should be further investigated to specify its potential as a comonomer and a matrix for pharmaceutical agents.

Three-dimensional (3D) printing has become a popular technique in many areas. One emerging field is the use of 3D printing for the development of 3D drug delivery systems (DDS) and drug-loaded medical devices. This article describes a novel concept for the fabrication of timecontrolled drug delivery systems based on stereolithography combined with inkjet printing. An inkjet printhead and an UV-LED light source have been integrated into an existing stereolithography system. Inkjet printing is used to selectively incorporate active pharmaceutical ingredients (API) during a stereolithographic 3D printing process. In an initial experimental study, poly (ethylene glycol) diacrylate (PEGDA) was used as polymer whereas 2-Hydroxy-4´-(2- hydroxyethoxy)-2-methylpropiophenone (Irgacure 2959) and Lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP) were used as photoinitiators. Basic structures could be manufactured successfully by the new hybrid 3D printing system.

Current research activities focus on personalized, comfortable and safe products for systemic or local drug application in patients. Poly(ethylene glycol) diacrylate is in particular interest as a drug delivery material, as it shows appropriate biological properties such as hydrophilicity and low toxicity. Additionally, as an easily photopolymerizable compound it can be also utilized for the production of scaffolds with the use of different techniques such as stereolithography. Even though it is often used as a biomaterial or as a copolymer in many photopolymer systems for drug delivery, thermomechanical analysis and basic understanding are rare.

The technology of pharmaceutical drug delivery systems (DDS) as an individual and adjustable tool for drug administration has been intensively developed in the last years. Additive manufacturing (AM) techniques, such as stereolithography, are a promising approach towards DDS scaffold manufacturing. Stereolithography, by using layerby- photo-polymerisation, creates DDS scaffolds with highly controlled 3D geometry. Combined with inkjet printing it allows a very precise positioning of the drug depot in the basic scaffold and therefore also a better control of the drug release. Furthermore, this hybrid AM technique also allows for the creation of a multi-drug DDS with a several drug depots localized in desired positions within the scaffold. Determination of the scaffold and drug depot material properties is one of the initial steps for such novel DDS development. Basic characteristics, such as stiffness, elasticity or glass transition temperature (Tg), are important for designing and adapting the material for biomedical application. The photosensitive poly(ethylene glycol) diacrylate (PEGDA) can be easily formed into a desired biocompatible scaffold geometry via stereolithography. In this study we have focused on the evaluation of PEGDA (Mn=700 g/mol) as a pure and copolymer system in combination with other acrylates (butanediol diacrylate, pentaerythritol triacrylate) as possible materials for DDS using this novel hybrid AM technique. Irgacure 2959, a biocompatible photoinitiator (PI), was used as a radical starter for photopolymerisation. Samples varying in PI and coacrylate concentration were prepared by conventional photopolymerisation. Physico-chemical analyses of the samples were performed and several parameters, such as stiffness, elongation at break and glass transition temperatures, were determined.

Novel fabrication techniques based on photopolymerization enable the preparation of complex multi-material constructs for biomedical applications. This requires an understanding of the influence of the used reaction components on the properties of the generated copolymers. The identification of fundamental characteristics of these copolymers is necessary to evaluate their potential for biomaterial applications. Additionally, knowledge of the properties of the starting materials enables subsequent tailoring of the biomaterials to meet individual implantation needs. In our study, we have analyzed the biological, chemical, mechanical and thermal properties of photopolymerized poly(ethyleneglycol) diacrylate (PEGDA) and specific copolymers with different photoinitiator (PI) concentrations before and after applying a post treatment washing process. As comonomers, 1,3-butanediol diacrylate, pentaerythritol triacrylate and pentaerythritol tetraacrylate were used. The in vitro studies confirm the biocompatibility of all investigated copolymers. Uniaxial tensile tests show significantly lower tensile strength (82% decrease) and elongation at break (76% decrease) values for washed samples. Altered tensile strength is also observed for different PI concentrations: on average, 6.2 MPa for 1.25% PI and 3.1 MPa for 0.5% PI. The addition of comonomers lowers elongation at break on average by 45%. Moreover, our observations show glass transition temperatures (Tg) ranging from 27 °C to 56 °C, which significantly increase with higher comonomer content. These results confirm the ability to generate biocompatible PEGDA copolymers with specific thermal and mechanical properties. These can be considered as resins for various additive manufacturing-based applications to obtain personalized medical devices, such as drug delivery systems (DDS). Therefore, our study has advanced the understanding of PEGDA multi-materials and will contribute to the future development of tools ensuring safe and effective individual therapy for patients. [ABSTRACT FROM AUTHOR]