Alginate Capsules with Cuttlebone-derived Fillers as an Integrated Solution for Bone Repair

Alginate capsules with cuttlebone-derived fillers were developed for bone repair applications. Prepared capsules were designed to be suitable for the treatment of small-sized bone loss provocative diseases, such as endodontic and periodontal diseases. Cuttlebone microparticles, as a source of calcium carbonate, or cuttlebone-derived hydroxyapatite microparticles were used as mineral fillers for the preparation of alginate capsules. The capsules were additionally covered with chitosan layer for the hard structure formation and improvement of adhesive properties. Encapsulation efficiency of dexamethasone as a model allopathic drug was 19 %, 24 % and 12 % for capsules with cuttlebone microparticles, capsules with cuttlebone-derived hydroxyapatite and capsules without any mineral filler (control group), respectively. We observed that chitosan coating and lyophilisation contributed for the preservation of spherical structure of alginate capsules with mineral fillers. Swelling study of dried capsules in simulated physiological environment (in phosphate buffer saline, pH = 7.2 at 37 °C temperature) showed that average swelling index of alginate-based capsules without mineral fillers was much higher in comparison to capsules with cuttlebone fillers: 121 %, 17 % and 3 % for control group, capsules with cuttlebone microparticles and capsules with cuttlebone-derived hydroxyapatite, respectively.DOI: http://dx.doi.org/10.5755/j01.ms.24.3.18858</p

Photoinitiator Free Resins Composed of Plant-Derived Monomers for the Optical µ-3D Printing of Thermosets

In this study, acrylated epoxidized soybean oil (AESO) and mixtures of AESO and vanillin dimethacrylate (VDM) or vanillin diacrylate (VDA) were investigated as photosensitive resins for optical 3D printing without any photoinitiator and solvent. The study of photocross-linking kinetics by real-time photorheometry revealed the higher rate of photocross-linking of pure AESO than that of AESO with VDM or VDA. Through the higher yield of the insoluble fraction, better thermal and mechanical properties were obtained for the pure AESO polymer. Here, for the first time, we validate that pure AESO and mixtures of AESO and VDM can be used for 3D microstructuring by employing direct laser writing lithography technique. The smallest achieved spatial features are 1 &micro;m with a throughput in 6900 voxels per second is obtained. The plant-derived resins were laser polymerized using ultrashort pulses by multiphoton absorption and avalanche induced cross-linking without the usage of any photoinitiator. This advances the light-based additive manufacturing towards the 3D processing of pure cross-linkable renewable materials

Life Cycle Assessment, Optical 3D printing of dental models using acrylic resin based on soybean oils

To facilitate the current transition toward a circular economy, the availability of renewable materials for additive manufacturing also becomes increasingly important. Additive manufacturing started in the 1980s with the development of the stereolithography apparatus (SLA) by Hull at 3D Systems (Hull 1984, Gross 2014). SLA printing is the layer-by-layer curing of liquid photopolymer resins using a focused laser beam. When a light projector is applied instead, exposing the entire layer to UV light simultaneously, the process is named digital light processing (DLP). Additive manufacturing via SLA or DLP process is applicable for high-resolution prototyping and fabrication of biomedical devices, for example, dental implants (l’Alzit 2022). The commercialized photopolymer resins used in SLA/DLP process are expensive and fossil fuel-based (Gross 2014, Voet 2021). The increased interest in bio-based products lead to active research and development that resulted in the development of vegetable oil-based 3D printable resin formulations. It is important to ensure that the new bio-based resin formulations do not have unintended environmental or health impacts from emissions during the production of novel ingredients, during the product use phase and during end-of-life disposal. Therefore, it is necessary to apply a holistic assessment tool to measure the sustainability of the resin formulation and the product made of it on a life cycle basis. Life Cycle Assessment (LCA) is a tool to assess the potential environmental impacts and resources used throughout a product’s life cycle, considering all potentially hazardous emissions and multiple categories of health and environmental impacts that result from those emissions (International Organization for Standartisation 2006). LCA can be used to investigate the most important contributors to environmental impacts by identifying the processes or materials in product life. Thus, it will provide data for designers to guide material selection, assist in supply chain management efforts, compare alternate designs or formulations, and provide product-level assessments that can be used for technology development and marketing (Montazeri 2018). The advancement in digital technology has increased the options available for dental treatment. To produce solid casts from digital data, there are two types of 3D manufacturing processes. Subtractive manufacturing is one of the processes that can produce 3D models (Kafle 2021). The other fabrication method being used is additive manufacturing such as 3D printing. This method of fabrication includes many advantages such as a minimum material usage with diminished waste accumulation during the production and the ability to create multiple products at a time (Kafle 2021). Dental model printing generally requires exceptional surface quality and very high accuracy as these models are used by dental technicians and dentists not only for a visual purpose but for the planning of dental treatment as well. Optical 3D printing here is also very beneficial as most of these prints are personalized, unique and applied to a specific customer only. Currently, the dental models are made from petroleum-based acrylic resins. Cradle-to-gate LCA results are compared across multiple impact categories to highlight potential environmental benefits or impacts of printing a batch of dental models from soybean oil-based resin formulation and provide recommendations for further improvements applicable to different life cycle phases of the product

Polymerization mechanisms initiated by spatio-temporally confined light

Ultrafast laser 3D lithography based on non-linear light–matter interactions, widely known as multi-photon lithography (MPL), offers unrivaled precision rapid prototyping and flexible additive manufacturing options. 3D printing equipment based on MPL is already commercially available, yet there is still no comprehensive understanding of factors determining spatial resolution, accuracy, fabrication throughput, repeatability, and standardized metrology methods for the accurate characterization of the produced 3D objects and their functionalities. The photoexcitation mechanisms, spatial-control or photo-modified volumes, and the variety of processable materials are topics actively investigated. The complexity of the research field is underlined by a limited understanding and fragmented knowledge of light-excitation and material response. Research to date has only provided case-specific findings on photoexcitation, chemical modification, and material characterization of the experimental data. In this review, we aim to provide a consistent and comprehensive summary of the existing literature on photopolymerization mechanisms under highly confined spatial and temporal conditions, where, besides the excitation and cross-linking, parameters such as diffusion, temperature accumulation, and the finite amount of monomer molecules start to become of critical importance. Key parameters such as photoexcitation, polymerization kinetics, and the properties of the additively manufactured materials at the nanoscale in 3D are examined, whereas, the perspectives for future research and as well as emerging applications are outlined

Polymerization mechanisms initiated by spatio-temporally confined light

Ultrafast laser 3D lithography based on non-linear light-matter interactions, widely known as multi-photon lithography (MPL), offers unrivaled precision rapid prototyping and flexible additive manufacturing options. 3D printing equipment based on MPL is already commercially available, yet there is still no comprehensive understanding of factors determining spatial resolution, accuracy, fabrication throughput, repeatability, and standardized metrology methods for the accurate characterization of the produced 3D objects and their functionalities. The photoexcitation mechanisms, spatial-control or photo-modified volumes, and the variety of processable materials are topics actively investigated. The complexity of the research field is underlined by a limited understanding and fragmented knowledge of light-excitation and material response. Research to date has only provided case-specific findings on photoexcitation, chemical modification, and material characterization of the experimental data. In this review, we aim to provide a consistent and comprehensive summary of the existing literature on photopolymerization mechanisms under highly confined spatial and temporal conditions, where, besides the excitation and cross-linking, parameters such as diffusion, temperature accumulation, and the finite amount of monomer molecules start to become of critical importance. Key parameters such as photoexcitation, polymerization kinetics, and the properties of the additively manufactured materials at the nanoscale in 3D are examined, whereas, the perspectives for future research and as well as emerging applications are outlined

UV-Cured Green Polymers for Biosensorics: Correlation of Operational Parameters of Highly Sensitive Biosensors with Nano-Volumes and Adsorption Properties

The investigated polymeric matrixes consisted of epoxidized linseed oil (ELO), acrylated epoxidized soybean oil (AESO), trimethylolpropane triglycidyl ether (RD1), vanillin dimethacrylate (VDM), triarylsulfonium hexafluorophosphate salts (PI), and 2,2-dimethoxy-2-phenylacetophenone (DMPA). Linseed oil-based (ELO/PI, ELO/10RD1/PI) and soybean oil-based (AESO/VDM, AESO/VDM/DMPA) polymers were obtained by cationic and radical photopolymerization reactions, respectively. In order to improve the cross-linking density of the resulting polymers, 10 mol.% of RD1 was used as a reactive diluent in the cationic photopolymerization of ELO. In parallel, VDM was used as a plasticizer in AESO radical photopolymerization reactions. Positron annihilation lifetime spectroscopy (PALS) was used to characterize vegetable oil-based UV-cured polymers regarding their structural stability in a wide range of temperatures (120–320 K) and humidity. The polymers were used as laccase immobilization matrixes for the construction of amperometric biosensors. A direct dependence of the main operational parameters of the biosensors and microscopical characteristics of polymer matrixes (mostly on the size of free volumes and water content) was established. The biosensors are intended for the detection of trace water pollution with xenobiotics, carcinogenic substances with a very negative impact on human health. These findings will allow better predictions for novel polymers as immobilization matrixes for biosensing or biotechnology applications