Electrospinning Nonspinnable Sols to Ceramic Fibers and Springs.

Electrospinning has been applied to produce ceramic fibers using sol gel-based spinning solutions consisting of ceramic precursors, a solvent, and a polymer to control the viscosity of the solution. However, the addition of polymers to the spinning solution makes the process more complex, increases the processing time, and results in porous mechanically weak ceramic fibers. Herein, we develop a coelectrospinning technique, where a nonspinnable sol (<10 mPa s) consisting of only the ceramic precursor(s) and solvent(s) is encapsulated inside a polymeric shell, forming core-shell precursor fibers that are further calcined into ceramic fibers with reduced porosity, decreased surface defects, uniform crystal packing, and controlled diameters. We demonstrate the versatility of this method by applying it to a series of nonspinnable sols and creating high-quality ceramic fibers containing TiO2, ZrO2, SiO2, and Al2O3. The polycrystalline TiO2 fibers possess excellent flexibility and a high Young's modulus reaching 54.3 MPa, solving the extreme brittleness problem of the previously reported TiO2 fibers. The single-component ZrO2 fibers exhibit a Young's modulus and toughness of 130.5 MPa and 11.9 KJ/m3, respectively, significantly superior to the counterparts prepared by conventional sol-gel electrospinning. We also report the creation of ceramic fibers in micro- and nanospring morphologies and examine the formation mechanisms using thermomechanical simulations. The fiber assemblies constructed by the helical fibers exhibit a density-normalized toughness of 3.5-5 times that of the straight fibers due to improved fracture strain. This work expands the selection of the electrospinning solution and enables the development of ceramic fibers with more attractive properties.

Unveiling the Mechanism of the in Situ Formation of 3D Fiber Macroassemblies with Controlled Properties.

Electrospinning technique is well-known for the generation of different fibers. While it is a "simple" technique, it lies in the fact that the fibers are typically produced in the form of densely packed two-dimensional (2D) mats with limited thickness, shape, and porosity. The highly demanded three-dimensional (3D) fiber assemblies have been explored by time-consuming postprocessing and/or complex setup modifications. Here, we use a classic electrospinning setup to directly produce 3D fiber macrostructures only by modulating the spinning solution. Increasing solution conductivity modifies electrodynamic jet behavior and fiber assembling process; both are observed in situ using a high-speed camera. More viscous solutions render thicker fibers that own enhanced mechanical stiffness as examined by finite element analysis. We reveal the correlation between the universal solution parameters and the dimensionality of fiber assemblies, thereof, enlightening the design of more "3D spinnable" solutions that are compatible with any commercial electrospinning equipment. After a calcination step, ultralightweight ceramic fiber assemblies are generated. These inexpensive materials can clean up exceptionally large fractions of oil spillages and provide high-performance thermal insulation. This work would drive the development and scale-up production of next-generation 3D fiber materials for engineering, biomedical, and environmental applications.

SPIO Enhance the Cross-Presentation and Migration of DCs and Anionic SPIO Influence the Nanoadjuvant Effects Related to Interleukin-1ß.

Superparamagnetic iron oxide nanoparticles (SPIO) have been synthesized and explored for use as carriers of various nanoadjuvants via loading into dendritic cells (DCs). In our study, homogeneous and superparamagnetic nanoparticles are susceptible to internalization by DCs and SPIO-pulsed DCs showed excellent biocompatibility and capacity for ovalbumin (OVA) cross-presentation. Herein, we found that SPIO-loaded DCs can promote the maturation and migration of DCs in vitro. SPIO coated with 3-aminopropyltrimethoxysilane (APTS) and meso-2,3-dimercaptosuccinic acid (DMSA), which present positive and negative charges, respectively, were prepared. We aimed to investigate whether the surface charge of SPIO can affect the antigen cross-presentation of the DCs. Additionally, the formation of interleukin-1ß (IL-1ß) was examined after treatment with oppositely charged SPIO to identify the nanoadjuvants mechanism. In conclusion, our results suggest that SPIO are biocompatible and can induce the migration of DCs into secondary lymph nodes. SPIO coated with APTS (SPIO/A+) exhibited excellent adjuvant potentials for the promotion of antigen cross-presentation and T cell activation and surpassed that of DMSA-coated nanoparticles (SPIO/D-). This process may be related to the secretion of IL-1ß. Our study provides insights into the predictive modification of nanoadjuvants, which will be valuable in DC vaccine design and could lead to the creation of new adjuvants for applications in vaccines for humans.

Polyethyleneimine modification of aluminum hydroxide nanoparticle enhances antigen transportation and cross-presentation of dendritic cells.

BACKGROUND: The aim of this study was to explore the feasibility of delivering tumor antigens and enhancing the antigen cross-presentation of dendritic cells (DCs) by aluminum hydroxide nanoparticle with polyethyleneimine (PEI) modification (LV@HPA/PEI). MATERIALS AND METHODS: The LV@HPA nanoparticles were modified by PEI first, then the influence of LV@HPA/PEI on DCs was examined. The distinct expression of ovalbumin (OVA) protein transported into DCs by LV@HPA/PEI was observed by flow cytometry and Western blot. The biocompatibility of LV@HPA/PEI, maturity and antigen cross-presentation of DCs was observed in vitro. Tumor derived autophagosomes (DRibbles) combined with LV@HPA/PEI were loaded into DCs, and DC vaccines were used to immunize mice. The percentage of CD3+CD8+IFN-γ+ T cells in immunized mice was determined by flow cytometry. Additionally, the functional properties of the LV@HPA/PEI-DRibble-DCs vaccine were examined in vivo in PancO2 tumor-bearing mice. RESULTS: In our study, we described how LV@HPA/PEI can be a functionalized antigen delivery system with notable antigen transport effect and negligible cytotoxicity. It was found that LV@HPA/PEI could be easily internalized into DCs to assist antigen release into the cytoplasm. In addition, DCs matured gradually after loading with LV@HPA/PEI-OVA, which increased significantly the cytokine IL-12 secretion and expression of surface molecules CD80 and CD86. Interestingly, DCs loaded with LV@HPA/PEI-DRibbles could promote the activation of tumor-specific T cells both in murine and in human T cells. In the following in vivo experiments, the vaccine of LV@HPA/PEI-DRibble-DCs significantly inhibited tumor growth and improved the survival rate of the PancO2 tumor-bearing mice. CONCLUSION: We established a high-performance anti-tumor vaccine of DCs loaded with LV@ HPA/PEI nanoparticles and tumor-associated antigens in autophagosomes (DRibbles), which could serve as a therapeutic strategy in cancer immunotherapy.