A new method of 'directed' self-assembly is demonstrated that has the potential to simply and quickly build nanostructured materials and devices. Called spin-spray layer-by-layer self-assembly (SSLbL), it is a modification of the well-known layer-by-layer method (LbL). Using SSLbL, it is possible to create and stack nanometre-thick, uniform layers containing a wide variety of different polymers, nanoparticles, or colloids in less than 25 s per bilayer, orders of magnitude faster than traditional LbL. This is done by modifying traditional dipping LbL to a system where carefully chosen volumes of polymer or colloidal solutions are sprayed directly on a rotating substrate. SSLbL is also much less wasteful of valuable nanoparticles and polymers than LbL. It is shown that in contrast to less than 1% material usage found in LbL, SSLbL has material usage efficiency up to 50%, and this can be further improved. Another direct result of the spin-spray modification is simple control of the in-plane structure of nanolayered films using masks, which is demonstrated. Such capability opens up the possibility of simply and inexpensively building complete nanocomposite devices with both vertical and lateral organization.
Designing electronic skin (e-skin) with proteins is a critical way to endow e-skin with biocompatibility, but engineering protein structures to achieve controllable mechanical properties and self-healing ability remains a challenge. Here, we develop a hybrid gluten network through the incorporation of a eutectic gallium indium alloy (EGaIn) to design a self-healable e-skin with improved mechanical properties. The intrinsic reversible disulfide bond/sulfhydryl group reconfiguration of gluten networks is explored as a driving force to introduce EGaIn as a chemical cross-linker, thus inducing secondary structure rearrangement of gluten to form additional β-sheets as physical cross-linkers. Remarkably, the obtained gluten-based material is self-healing, achieves synthetic material-like stretchability (>1600%) and possesses the ability to promote skin cell proliferation. The final e-skin is biocompatible and biodegradable and can sense strain changes from human motions of different scales. The protein network microregulation method paves the way for future skin-like protein-based e-skin.
Cryopreservation of few spermatozoa is still a major challenge for male fertility preservation. This study reports use a new micro-straw (LSL straw) for freezing few spermatozoa for intracytoplasmic sperm injection (ICSI). Semen samples from 22 fertile donors were collected, and each semen sample was diluted and mixed with cryoprotectant in a ratio of 1:1, and then frozen using three different straws such as LSL straw (50–100 μl), traditional 0.25 ml and 0.5 ml straws. For freezing, all straws were fumigated with liquid nitrogen, with temperature directly reducing to −130–−140°C. Sperm concentration, progressive motility, morphology, acrosome integrity, and DNA fragmentation index were evaluated before and after freezing. After freezing-thawing, LSL straw group had significantly higher percentage of sperm motility than traditional 0.25 ml and 0.5 ml straw groups (38.5% vs 27.4% and 25.6%, P < 0.003). Sperm motility and acrosomal integrity after freezing-thawing were significantly lower than that of before freezing. However, there was no significant difference in morphology, acrosome, and DNA integrity between the three types of straws (P > 0.05). As LSL straws were thinner and hold very small volume, the freezing rate of LSL straw was obviously faster than 0.25 ml straw and 0.5 ml straws. In conclusion, LSL micro-straws may be useful to store few motile spermatozoa with good recovery of motility for patients undergoing ICSI treatment.
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