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  1. This article belongs to the Special Issue Hydrogels with Appropriate/Tunable Properties for Biomedical Applications (Ed.)

    Pulmonary drug delivery via microspheres has gained growing interest as a noninvasive method for therapy. However, drug delivery through the lungs via inhalation faces great challenges due to the natural defense mechanisms of the respiratory tract, such as the removal or deactivation of drugs. This study aims to develop a natural polymer-based microsphere system with a diameter of around 3 μm for encapsulating pulmonary drugs and facilitating their delivery to the deep lungs. Pectin was chosen as the foundational material due to its biocompatibility and degradability in physiological environments. Electrospray was used to produce the pectin-based hydrogel microspheres, and Design-Expert software was used to optimize the production process for microsphere size and uniformity. The optimized conditions were determined to be as follows: pectin/PEO ratio of 3:1, voltage of 14.4 kV, distance of 18.2 cm, and flow rate of 0.95 mL/h. The stability and responsiveness of the pectin-based hydrogel microspheres can be altered through coatings such as gelatin. Furthermore, the potential of the microspheres for pulmonary drug delivery (i.e., their responsiveness to the deep lung environment) was investigated. Successfully coated microspheres with 0.75% gelatin in 0.3 M mannitol exhibited improved stability while retaining high responsiveness in the simulated lung fluid (Gamble’s solution). A gelatin-coated pectin-based microsphere system was developed, which could potentially be used for targeted drug delivery to reach the deep lungs and rapid release of the drug.

     
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    Free, publicly-accessible full text available September 1, 2024
  2. Guy Van der Mooter (Ed.)

    The development of vascularized tissue is a substantial challenge within the field of tissue engineering and regenerative medicine. Studies have shown that positively-charged microspheres exhibit dual-functions: (1) facilitation of vascularization and (2) controlled release of bioactive compounds. In this study, gelatin-coated microspheres were produced and processed with either EDC or transglutaminase, two crosslinkers. The results indicated that the processing stages did not significantly impact the size of the microspheres. EDC and transglutaminase had different effects on surface morphology and microsphere stability in a simulated colonic environment. Incorporation of EGM and TGM into bioink did not negatively impact bioprintability (as indicated by density and kinematic viscosity), and the microspheres had a uniform distribution within the scaffold. These microspheres show great potential for tissue engineering applications.

     
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  3. IMECE2022-88301 Additive manufacturing (AM) is transforming industrial production. AM can produce parts with complex geometries and functionality. However, one of the biggest challenges in the AM world is limited material options. The purpose of this research is to develop new material mixtures and determine their mechanical properties for use at the MSOE Rapid Prototyping Center and provide valuable insight into beta materials for use in AM industry. Elastomeric polyurethane (EPU 40) and Rigid polyurethane (RPU 70), resins developed by Carbon3D, are employed for this research. Initially, EPU 40 (100%) and RPU 70 (100%) were used to print tensile and hardness test specimens so that their mechanical properties could be compared to the standard values presented by Carbon3D and used as benchmarks for newly developed material. Mixtures of the two materials, EPU 40 and RPU 70, in multiple ratios were then created and used to print tensile and hardness test specimens. Data collected from tensile and hardness tests show that EPU 40 and RPU 70 can be combined in various ratios to obtain material properties that lie between the two individual components. In addition to developing these new materials, the effect of printing orientation on mechanical properties was also studied in this paper. 
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  4. IMECE2022-88299 Midwest Engineered Systems Inc. has created a novel laser wire metal deposition process, ADDere manufacturing. ADDere has a much higher deposition rate than powder bed fusion, making it ideal for large components. In this project, the mechanical properties of ADDere printed materials were tested and compared to typical values found in ASM publications to show the quality of materials manufactured by the ADDere printing process. A detailed material analysis was performed on samples made from Ti-6Al-4V and 17-4 PH stainless steel. This work builds upon an earlier study of samples made from 17-4 PH that were produced using a single direction pattern. In this project, the 17-4 PH samples were printed in a cross hatched pattern, and testing results were compared to existing data from single direction samples of the previous research. The Ti-6Al-4V samples were created in two builds. One using the uni-directional method and the other with the crossed pattern. Testing specimens were removed from the samples using a water jet cutter and further machined into ASTM tensile bars and metallurgic mounts to perform a thorough material evaluation. The Ti-6Al-4V sample met the expected values in the ASM literature, and the cross hatched 17-4 PH exhibited a higher hardness and better microstructure than the single direction samples from the previous work. It was also observed that when the Ti64 samples were manufactured in the cross hatched pattern, the properties indicated slight improvement and more homogeneity than those printed in single layer direction. The obtained results indicate that ADDere’s printing process can produce highly refined materials that are customizable with their expected uses. This work showcases an excellent industry collaboration of an undergraduate research experience. 
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  5. This article belongs to the Special Issue Synthesis and Applications of Gold Nanoparticles) Rodolphe Antoine (Ed.)

    This research focuses on the plant-mediated green synthesis process to produce gold nanoparticles (Au NPs) using upland cress (Barbarea verna), as various biomolecules within the upland cress act as both reducing and capping agents. The synthesized gold nanoparticles were thoroughly characterized using UV-vis spectroscopy, surface charge (zeta potential) analysis, scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDX), atomic force microscopy (AFM), attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), and X-ray diffraction (XRD). The results indicated the synthesized Au NPs are spherical and well-dispersed with an average diameter ~11 nm and a characteristic absorbance peak at ~529 nm. EDX results showed an 11.13% gold content. Colloidal Au NP stability was confirmed with a zeta potential (ζ) value of −36.8 mV. X-ray diffraction analysis verified the production of crystalline face-centered cubic gold. Moreover, the antimicrobial activity of the Au NPs was evaluated using Gram-negative Escherichiacoli and Gram-positive Bacillus megaterium. Results demonstrated concentration-dependent antimicrobial properties. Lastly, applications of the Au NPs in catalysis and biomedicine were evaluated. The catalytic activity of Au NPs was demonstrated through the conversion of 4-nitrophenol to 4-aminophenol which followed first-order kinetics. Cellular uptake and cytotoxicity were evaluated using both BMSCs (stem) and HeLa (cancer) cells and the results were cell type dependent. The synthesized Au NPs show great potential for various applications such as catalysis, pharmaceutics, and biomedicine.

     
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  6. A major challenge in tissue engineering is the formation of vasculature in tissue and organs. Recent studies have shown that positively charged microspheres promote vascularization, while also supporting the controlled release of bioactive molecules. This study investigated the development of gelatin-coated pectin microspheres for incorporation into a novel bioink. Electrospray was used to produce the microspheres. The process was optimized using Design-Expert® software. Microspheres underwent gelatin coating and EDC catalysis modifications. The results showed that the concentration of pectin solution impacted roundness and uniformity primarily, while flow rate affected size most significantly. The optimal gelatin concentration for microsphere coating was determined to be 0.75%, and gelatin coating led to a positively charged surface. When incorporated into bioink, the microspheres did not significantly alter viscosity, and they distributed evenly in bioink. These microspheres show great promise for incorporation into bioink for tissue engineering applications. 
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