Engineered Platelet-Derived Growth Factor-Releasing Hydrogels Promote Fetal Membrane Healing In Vivo

Fetoscopic interventions to treat fetal anomalies are currently performed for a variety of conditions. Depending on the procedure, preterm rupture of the fetal membranes (FMs) happens in around 30% of the cases, potentially leading to preterm birth and fetal morbidity and mortality. Here, the capacity of modular transglutaminase crosslinked poly(ethylene glycol) (TG-PEG) hydrogels that release platelet-derived growth factor (PDGF)-BB to promote FM healing is described. In vitro, such growth factor-loaded hydrogels are able to stimulate amniotic cell migration and proliferation. When applied in vivo, these TG-PEG hydrogels tightly seal the FM and uterus defects created by a fetoscope and remain stable for 10 days. The migration of healing-related cells into such hydrogels in the myometrium, endometrium, and FM areas is only possible in soft TG-PEG hydrogels. Importantly, bioengineered hydrogels releasing PDGF-BB promote recruitment of host cells from the myometrium and the endometrium, and to a lesser extent from FM areas. In such hydrogels, the potent proliferation and matrix production of the recruited cells at the site of treatment into the biomaterial initiates a robust early healing response. PDGF-BB-loaded TG-PEG hydrogels hold great promise for the treatment of fetoscopy-induced FM defects and for the prevention of preterm birth.     

High-Resolution Patterning of Organic–Inorganic Photoresins for Tungsten and Tungsten Carbide Microstructures

Tungsten is an important material for high-temperature applications due to its high chemical and thermal stability. Its carbide, that is, tungsten carbide, is used in tool manufacturing because of its outstanding hardness and as a catalyst scaffold due to its morphology and large surface area. However, microstructuring, especially high-resolution 3D microstructuring of both materials, is a complex and challenging process which suffers from slow speeds and requires expensive specialized equipment. Traditional subtractive machining methods, for example, milling, are often not feasible because of the hardness and brittleness of the materials. Commonly, tungsten and tungsten carbide are manufactured by powder metallurgy. However, these methods are very limited in the complexity and resolution of the produced components. Herein, tungsten ion-containing organic–inorganic photoresins, which are patterned by two-photon lithography (TPL) at micrometer resolution, are introduced. The printed structures are converted to tungsten or tungsten carbide by thermal debinding and reduction of the precursor or carbothermal reduction reaction, respectively. Using TPL, complex 3D tungsten and tungsten carbide structures are prepared with a resolution down to 2 and 7 μm, respectively. This new pathway of structuring tungsten and its carbide facilitates a broad range of applications from micromachining to metamaterials and catalysis.     

A novel predictive homotopic path tracking algorithm to solve non-linear algebraic equations

In chemical engineering and other areas of mathematics and engineering sciences, systems of non-linear algebraic equations often must be solved, and a problem is that these types of systems often cannot be solved analytically. Homotopic continuation methods are globally convergent and can find several solutions to the analyzed algebraic system and consist of a predictive step followed by a corrective step, which can cause reversion of homotopic path tracking. Therefore, in this work, the use of a homotopy continuation method (HCM) based on a purely predictive methodology is proposed; that is, it only makes use of predictor vectors (without correction vectors) to find the solution to several systems of non-linear algebraic equations with a multiplicity of solutions, employing lower central proccessing unit (CPU) time in comparison with standard homotopic tracking algorithms.