3D-printed extraction devices fabricated from silica particles suspended in acrylate resin

In recent years, there has been an increasing worldwide interest in the use of alternative sample preparation methods. Digital light processing (DLP) is a 3D printing technique based on using UV light to form photo-curable resin layer upon layer, which results in a printed shape. This study explores the application of this technique for the development of novel drug extraction devices in analytical chemistry. A composite material consisting of a photocurable resin and C18-modified silica particles was employed as a sorbent device, demonstrating its effectiveness in pharmaceutical analysis. Apart from estimating optimal printing parameters, microscopic examination of the material surface, and sorbent powder to resin ratio, the extraction procedure was also optimised. Optimisation included the type and amount of sample matrix additives, desorption solvent, sorption and desorption times, and proper number of sorbent devices needed in extraction protocol. To demonstrate this method's applicability for sample analysis, the solid-phase extraction followed by gas chromatography coupled with mass spectrometry (SPE-GC-MS) method was validated for its ability to quantify benzodiazepine-type drugs. This evaluation confirmed good linearity in the concentration range of 50-1000 ng/mL, with R2 values being 0.9932 and 0.9952 for medazepam and diazepam, respectively. Validation parameters proved that the presented method is precise (with values ranging in-between 2.98 %-7.40 %), and accurate (88.81 % to 110.80 %). A negative control was also performed to investigate possible sorption properties of the resin itself, proving that the addition of C18-modified silica particles significantly increases the extraction efficiency and repeatability. The cost-effectiveness of this approach makes it particularly advantageous for single-use scenarios, eliminating the need for time-consuming sorbent-cleaning procedures, common in traditional solid-phase extraction techniques. Future optimisation opportunities include refining sorbent size, shape, and geometry to achieve lower limits of quantification. As a result of these findings, 3D-printed extraction devices can serve as a viable alternative to commercially available SPE or solid-phase microextraction (SPME) protocols for studying new sample preparation approaches.

An Affordable NIR Spectroscopic System for Fraud Detection in Olive Oil

Adulterations of olive oil are performed by adding seed oils to this high-quality product, which are cheaper than olive oils. Food safety controls have been established by the European Union to avoid these episodes. Most of these methodologies require expensive equipment, time-consuming procedures, and expert personnel to execute. Near-infrared spectroscopy (NIRS) technology has many applications in the food processing industry. It analyzes food safety and quality parameters along the food chain. Using principal component analysis (PCA), the differences and similarities between olive oil and seed oils (sesame, sunflower, and flax oil) have been evaluated. To quantify the percentage of adulterated seed oil in olive oils, partial least squares (PLS) have been employed. A total of 96 samples of olive oil adulterated with seed oils were prepared. These samples were used to build a spectra library covering various mixtures containing seed oils and olive oil contents. Eighteen chemometric models were developed by combining the first and second derivatives with Standard Normal Variable (SNV) for scatter correction to classify and quantify seed oil adulteration and percentage. The results obtained for all seed oils show excellent coefficients of determination for calibration higher than 0.80. Because the instrumental aspects are not generally sufficiently addressed in the articles, we include a specific section on some key aspects of developing a high-performance and cost-effective NIR spectroscopy solution for fraud detection in olive oil. First, spectroscopy architectures are introduced, especially the Texas Instruments Digital Light Processing (DLP) technology for spectroscopy that has been used in this work. These results demonstrate that the portable prototype can be used as an effective tool to detect food fraud in liquid samples.

Study on CerAMfacturing of Novel Alumina Aerospike Nozzles by Lithography-Based Ceramic Vat Photopolymerization (CerAM VPP)

Advanced ceramics are recognized as key enabling materials possessing combinations of properties not achievable in other material classes. They provide very high thermal, chemical and mechanical resistance and typically exhibit lower densities than metals. These properties predestine ceramics for many different applications, especially those in space. Aerospike nozzles promise an increased performance compared to classic bell nozzles but are also inherently more complex to manufacture due to their shape. Additive manufacturing (AM) drastically simplifies or even enables the fabrication of very complex structures while minimizing the number of individual parts. The applicability of ceramic AM (“CerAMfacturing”) on rocket engines and especially nozzles is consequently investigated in the frame of the “MACARONIS” project, a cooperation of the Institute of Aerospace Engineering at Technische Universität Dresden and the Fraunhofer Institute for Ceramic Technologies and Systems (IKTS) in Dresden. The goal is to develop novel filigree aerospike nozzles with 2.5 N and 10 N thrust. For this purpose, CerAM VPP (ceramic AM via Vat Photopolymerization) using photoreactive and highly particle-filled suspensions was utilized. This contribution gives an overview of the component development starting from CAD modeling, suspension development based on alumina AES-11C, heat treatment and investigation of the microstructure of the sintered components. It could be shown that modifying the suspension composition significantly reduced the formation of cracks during processing, resulting in defect-free filigree aerospike nozzles for application in space.

Hydrophilic excipients in digital light processing (DLP) printing of sustained release tablets: Impact on internal structure and drug dissolution rate

Three-dimensional (3D) printing enables the production of different objects adjusted for the specific application, which has particular importance of providing personalized therapy, whereby the challenge is to apply pharmaceutical materials into 3D printing technology. In this study, effect of poly(ethylene glycol) 400 (PEG 400), sodium chloride (NaCl), and mannitol, as hydrophilic excipients, was investigated in order to overcome very slow and incomplete drug release from tablets (printlets) fabricated by photopolymerization using digital light processing (DLP) technology. Paracetamol (acetaminophen) was used as a model drug, while polyethylene glycol diacrylate (PEGDA) was used as a photopolymer and diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide as a photoinitiator in photoreactive mixtures. Most of printlet formulations exhibit sustained release over 8 h, wherein drug release kinetics is the best described with Korsmeyer-Peppas kinetics. Variation in the content of photopolymer and excipients had an influence on the dissolution rate, mechanical characteristics, and internal structure of the investigated samples. The addition of hydrophilic polymers increased drug release rate, while PEGDA had the greatest influence on the tensile strength of printlets. The results indicate the possibility of implementation of traditional excipients into different formulations for photopolymerization based 3D printing for the production of small batches of tablets with tailored drug release.

Optimization of photocrosslinkable resin components and 3D printing process parameters

The role of 3D printing in the biomedical field is growing. In this context, photocrosslink-based 3D printing procedures for resorbable polymers stand out. Despite much work, more studies are needed on photocuring stereochemistry, new resin additives, new polymers and resin components. As part of these studies it is vital to present the logic used to optimize the amount of each resin constituent and how that effects printing process parameters. The present manuscript aims to analyze the effects of poly(propylene fumarate) (PPF) resin components and their effect on 3D printing process parameters. Diethyl fumarate (DEF), bisacylphosphine oxide (BAPO), Irgacure 784, 2-hydroxy-4-methoxybenzophenone (HMB) and, for the first time, in biomedical 3D printing, ethyl acetate (EA), were the resin components under investigation in this study. Regarding printing process parameters, Exposure Time, Voxel Depth, and Overcuring Depth were the parameters studied. Taguchi Design of Experiments was used to search for the effect of varying these resin constituent concentrations and 3D printing parameters on the curing behavior of 3D printable PPF resins. Our results indicate that resins with higher polymer cross-link density, especially those with a higher content of PPF, are able to be printed at higher voxel depth and with greater success (i.e., high yield). High voxel depth, as long as it does not sacrifice required resolution, is desirable as it speeds printing. Nevertheless, the overall process is governed by the correct setup of the voxel depth in relation to overcuring depth. In regards to resin biocompatibility, it was observed that EA is more effective than DEF, the material we had previously relied on. Our preliminary in vitro cytotoxicity tests indicate that the use of EA does not reduce scaffold biocompatibility as measured by standard cytotoxicity testing (i.e., ISO 10993-5). We demonstrate a workpath for resin constituent concentration optimization through thin film tests and photocrosslinkable process optimization. STATEMENT OF SIGNIFICANCE: We report here the results of a study of photo-crosslinkable polymer resin component optimization for the 3D printing of resorbable poly(propylene fumarate) (PPF) scaffolds. Resin additives are initially optimized for PPF thin film printing. Once those parameters have been optimized the 3D printing process parameters for PPF objects with complex, porous shapes can be optimized. The design of experiments to optimize both polymer thin films and complex porous resorbable polymer scaffolds is important as a guess and check, or in some cases a systematic method, are very likely to be too time consuming to accomplish. Previously unstudied resin components and process parameters are reported.

3D Printing a Mechanically-Tunable Acrylate Resin on a Commercial DLP-SLA Printer

Multi-material 3D printing with several mechanically distinct materials at once has expanded the potential applications for additive manufacturing technology. Fewer material options exist, however, for additive systems that employ vat photopolymerization (such as stereolithography, SLA, and digital light projection, DLP, 3D printers), which are more commonly used for advanced engineering prototypes and manufacturing. Those material selections that do exist are limited in their capacity for fusion due to disparate chemical and physical properties, limiting the potential mechanical range for multi-material printed composites. Here, we present an ethylene glycol phenyl ether acrylate (EGPEA)-based formulation for a polymer resin yielding a range of elastic moduli between 0.6 MPa and 33 MPa simply by altering the ratio of monomer and crosslinker feedstocks in the formulation. This simple chemistry is also well suited to form seamless adhesions between mechanically dissimilar formulations, making it a promising candidate for multi-material DLP 3D printing. Preliminary tests with these polymer formulations indicate that variability due to molecular differences between hard and soft formulations is near net shape and less than 3% of the prescribed dimensions, comparable to existing commercial DLP and SLA resins, with unique advantages of a wide range of elastomer stiffness and seamless fusion for 3D printing of structurally detailed and mechanically heterogeneous composites.