Controllable Microfluidic Fabrication of Microstructured Materials from Nonspherical Particles to Helices.

This work reports on a facile and flexible strategy based on the deformation of encapsulated droplets in fiber-like polymeric matrices for template synthesis of controllable microstructured materials from nonspherical microparticles to complex 3D helices. Monodisperse droplets generated from microfluidics are encapsulated into crosslinked polymeric networks via an interfacial crosslinking reaction in microchannel to in situ produce the droplet-containing, fiber-like matrices. By stretching and twining the dried fiber-like matrices, the encapsulated droplets can be flexibly engineered into versatile shapes for template synthesis of controllable nonspherical microparticles and helices. Moreover, magnetic helices can be fabricated by simply dispersing magnetic Fe3 O4 nanoparticles in the droplets to achieve rotational and translational motion under a rotated magnetic field. This work provides a simple and versatile strategy for the template synthesis of advanced functional microstructured materials with flexible shapes.

Controllable Multicompartmental Capsules with Distinct Cores and Shells for Synergistic Release.

A facile and flexible approach is developed for controllable fabrication of novel multiple-compartmental calcium alginate capsules from all-aqueous droplet templates with combined coextrusion minifluidic devices for isolated coencapsulation and synergistic release of diverse incompatible components. The multicompartmental capsules exhibit distinct compartments, each of which is covered by a distinct part of a heterogeneous shell. The volume and number of multiple compartments can be well-controlled by adjusting flow rates and device numbers for isolated and optimized encapsulation of different components, while the composition of different part of the heterogeneous shell can be individually tailored by changing the composition of droplet template for flexibly tuning the release behavior of each component. Two combined devices are first used to fabricate dual-compartmental capsules and then scaled up to fabricate more complex triple-compartmental capsules for coencapsulation. The synergistic release properties are demonstrated by using dual-compartmental capsules, which contain one-half shell with a constant release rate and the other half shell with a temperature-dependent release rate. Such a heterogeneous shell provides more flexibilities for synergistic release with controllable release sequence and release rates to achieve advanced and optimized synergistic efficacy. The multicompartmental capsules show high potential for applications such as drug codelivery, confined reactions, enzyme immobilizations, and cell cultures.

The microfluidic synthesis of composite hollow microfibers for K+-responsive controlled release based on a host-guest system.

A novel type of composite hollow microfiber with K+-responsive controlled-release characteristics based on a host-guest system is prepared by embedding K+-responsive poly(N-isopropylacrylamide-co-acryloylamidobenzo-15-crown-5) (P(NIPAM-co-AAB15C5)) microspheres in the wall of poly(lactic-co-glycolic acid) (PLGA) microfibers as "micro-valves" using a controllable microfluidic approach. By adjusting the volume change of microspheres in response to the environmental K+ concentration, the release rate of the encapsulated drug molecules from the composite hollow microfibers can be flexibly regulated owing to the change in the interspace size between the microfiber wall and microspheres. When the environmental K+ concentration is increased, due to the formation of stable 2 : 1 "sandwich-type" host-guest complexes of 15-crown-5 units and K+ ions, P(NIPAM-co-AAB15C5) microspheres change from a swollen state to a shrunken state. Thus, the interspace size becomes larger, resulting in a rapid increase in the release rate of encapsulated drugs. When the ambient K+ concentration is decreased, the interspace size becomes smaller due to isothermal swelling of microspheres caused by the decreased amount of host-guest complexes, resulting in a decrease in the release rate. The K+-responsive drug release behaviors are reversible. This kind of K+-responsive hollow microfiber with K+-concentration-dependent controlled-release properties provides a new mode in the design of more rational drug delivery systems, which are highly attractive for biomedical applications.

A novel synthetic microfiber with controllable size for cell encapsulation and culture.

A facile and controllable microfluidic strategy is developed to fabricate synthetic microfibers of crosslinked 4-arm polyethylene glycol with maleimide end groups (PEG-4Mal) for cell encapsulation and culture with high viability. The gelling condition in this strategy is mild for cell encapsulation and the crosslinking process is rapid, thus guaranteeing the high viability of encapsulated cells. The diameters of PEG-4Mal synthetic microfibers are precisely adjustable by simply changing the flowrates of the inner and outer fluids in microfluidic devices. The prepared PEG-4Mal synthetic microfibers possess excellent permselectivity, which could not only guarantee the normal metabolism of encapsulated cells but also provide immunoisolation for encapsulated cells. MC3T3 cells and NIH3T3 cells are successfully encapsulated into the PEG-4Mal synthetic microfibers, and the formed microfibers enable high viability for cell encapsulation and culture. The proposed PEG-4Mal synthetic microfibers show great potential as efficient cell encapsulation systems for many potential biomedical applications in cell culture, cell therapy and tissue engineering.

Microfluidic Fabrication of Bio-Inspired Microfibers with Controllable Magnetic Spindle-Knots for 3D Assembly and Water Collection.

A simple and flexible approach is developed for controllable fabrication of spider-silk-like microfibers with tunable magnetic spindle-knots from biocompatible calcium alginate for controlled 3D assembly and water collection. Liquid jet templates with volatile oil drops containing magnetic Fe3O4 nanoparticles are generated from microfluidics for fabricating spider-silk-like microfibers. The structure of jet templates can be precisely adjusted by simply changing the flow rates to tailor the structures of the resultant spider-silk-like microfibers. The microfibers can be well manipulated by external magnetic fields for controllably moving, and patterning and assembling into different 2D and 3D structures. Moreover, the dehydrated spider-silk-like microfibers, with magnetic spindle-knots for collecting water drops, can be controllably assembled into spider-web-like structures for excellent water collection. These spider-silk-like microfibers are promising as functional building blocks for engineering complex 3D scaffolds for water collection, cell culture, and tissue engineering.

[Expression of matrix metalloproteinases in the cytotrophoblasts and decidual stromal cells in human early pregnancy].

OBJECTIVE: To study the expression of matrix metalloproteinases (MMPs ) in the decidual stromal cells (DSCs) and extravillous cytotrophoblasts (EVCT) in human early pregnancy and explore the change of MMPs in endometrial stromal cell (ESC) decidualization and its impact on implantation and placentation. METHODS: The decidua and villi from 5 women with early pregnancy and mid-secretory endometrium from 5 normal women were collected and cultured in vitro, and the supernatants of the culture media were collected after 48 hours of incubation. The expression of the MMPs in the ESCs, DSCs and EVCTs was detected using Luminex xMAP system simultaneously and the difference in MMPs expression and their correlations were analyzed with SPSS10.0 software. RESULTS: The MMPs (MMP-1, MMP-2, MMP-3, MMP-7, MMP-8, and MMP-9) were expressed in ESCs, DSCs and EVCTs, while MMP-12 was not found in ESCs and MMP-13 not in DSCs. Expressions of MMP-8, MMP-12, and MMP-13 were lowered. Compared with the ESCs, DSCs and EVCTs showed significantly lowered expressions of MMP-1, MMP-3, and MMP-7 (P<0.05), whereas expression of MMP-2 and MMP-9 increased significantly, and the high expressions of MMP-1, MMP-3, and MMP-7 was especially obvious in the DSCs. The expressions of MMP-1, MMP-3, and MMP-7, however, were significantly decreased in the EVCTs in comparison with the DSCs. Significant correlations were noted between MMP-1, MMP-3, and MMP-7, and MMP-2 was closely correlated with MMP-9. MMP-8 was significantly lower and MMP-12 and MMP-13 showed no obvious variation in the cell culture. CONCLUSION: MMPs are secreted by ESCs, DSCs and EVCTs. Diverse MMPs play an important role in proliferation and differentiation of the ESC to affect embryo implantation and placentation. All MMPs establish a balance to co-regulate the process of pregnancy.