“From Academia” features recent, relevant, close to commercialization academic publications. Subjects include but not limited to healthcare 3D printing, 3D bioprinting, and related emerging technologies.
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Drug Incorporation into Polymer Filament Using Simple Soaking Method for Tablet Preparation Using Fused Deposition Modeling
The use of three-dimensional (3D) printing technology is expanding in various fields. The application of 3D printing is expected to increase in the pharmaceutical industry after 3D-printed tablets were approved by the U.S. Food and Drug Administration (FDA). Fused deposition modeling (FDM), a type of 3D printing, has been extensively studied for the manufacturing of tablets. A drug-loaded polymer filament, the ink of FDM 3D printers, can be prepared using the hot melt extrusion method or a simple drug-soaking method. In the present study, we investigate the influence of the experimental conditions on the loading of curcumin (model drug with fluorescence) into a polyvinylalcohol polymer filament using the soaking method. We show that organic solvent type (isopropanol, methanol, acetone, and ethanol), temperature (25 and 80°C), and drug concentration (2-333 mg/mL) greatly affect drug loading. Around 5% curcumin can be incorporated into the polyvinylalcohol filament using the soaking method. The drug dissolution from 3D-printed tablets depends on the drug content in the polymer filament. The incorporation of a higher amount of curcumin, which has poor water solubility, greatly delays drug dissolution. These results provide useful information on the preparation of 3D-printed tablets using a drug-loaded polymer filament obtained with the soaking method.
Recent advances in three-dimensional (3D) printing technology has enabled to shape food in unique and complex 3D shapes. To showcase the capability of 3D food printing, chocolates have been commonly used as printing inks, and 3D printing based on hot-melt extrusion have been demonstrated to model 3D chocolate products. Although hot-melt extrusion of chocolates is simple, the printing requires precise control over the operating temperature in a narrow range. In this work, for the first time, we directly printed chocolate-based inks in its liquid phase using direct ink writing (DIW) 3D printer to model complex 3D shapes without temperature control. We termed this method as chocolate-based ink 3D printing (Ci3DP). The printing inks were prepared by mixing readily available chocolate syrup and paste with cocoa powders at 5 to 25 w/w% to achieve desired rheological properties. High concentrations of cocoa powders in the chocolate-based inks exhibited shear-thinning properties with viscosities ranging from 102 to 104 Pa.s; the inks also possessed finite yield stresses at rest. Rheology of the inks was analyzed by quantifying the degree of shear-thinning by fitting the experimental data of shear stress as a function of shear rate to Herschel-Bulkley model. We demonstrated fabrication of 3D models consisting of chocolate syrups and pastes mixed with the concentration of cocoa powders at 10 to 25 w/w%. The same method was extended to fabricate chocolate-based models consisting of multiple type of chocolate-based inks (e.g. semi-solid enclosure and liquid filling). The simplicity and flexibility of Ci3DP offer great potentials in fabricating complex chocolate-based products without temperature control.
Shape-morphing structured materials have the ability to transform a range of applications. However, their design and fabrication remain challenging due to the difficulty of controlling the underlying metric tensor in space and time. Here, we exploit a combination of multiple materials, geometry, and 4-dimensional (4D) printing to create structured heterogeneous lattices that overcome this problem. Our printable inks are composed of elastomeric matrices with tunable cross-link density and anisotropic filler that enable precise control of their elastic modulus (E) and coefficient of thermal expansion. The inks are printed in the form of lattices with curved bilayer ribs whose geometry is individually programmed to achieve local control over the metric tensor. For independent control of extrinsic curvature, we created multiplexed bilayer ribs composed of 4 materials, which enables us to encode a wide range of 3-dimensional (3D) shape changes in response to temperature. As exemplars, we designed and printed planar lattices that morph into frequency-shifting antennae and a human face, demonstrating functionality and geometric complexity, respectively. Our inverse geometric design and multi-material 4D printing method can be readily extended to other stimuli-responsive materials and different 2-dimensional (2D) and 3D cell designs to create scalable, reversible, shape-shifting structures with unprecedented complexity.
Dynamic imine bonds based shape memory polymers with permanent shape reconfigurability for 4D printing
Shape memory polymer (SMP)-based 4D printing combines the advantages of SMP and 3D printing to form active materials with delicate structure. Nowadays, studies of SMP-based 4D printing materials mainly focus on crosslinked (meth)acrylate, of which the permanent shape cannot be changed for their covalent linkage, limiting the usage of 4D printing materials. In this paper, a novel methacrylate monomer with aldehyde group (2-(methacryloyloxy)ethyl 4-formylbenzoate, MEFB) and hyperbranched crosslinker (HPASi) are synthesized to build (meth)acrylate systems (IEMSis) with dynamic imine bonds for 4D printing. The flexible chain structure of HPASi significantly enhances the toughness of IEMSis, which are 33-97-fold higher than that of the one without HPASi (IEM). The addition of HPASi also endows IEMSis good shape memory properties, and the shape fixity ratio and shape recovery ratio of them are 97.5-97.6 % and 91.4-93.7 %, respectively. At the same time, IEMSis can undergo stress relaxation process by dynamic exchanges of imine bonds under relatively mild conditions without catalyst, thus to acquire an ability of permanent shape reconfiguration. The shape retention ratio of IEMSi3 is 84.3 %. In addition, the 4D printed structures displayed here indicate that these 4D printing systems have a myriad of potential applications including aerospace structures, soft robotic grippers and smart electron switches, while the reconfigurability shown by IEMSi3 will expand the scope of application fields of 4D printing materials.