Study on the Preparation of Ionic Liquid Doped Chitosan/Cellulose-Based Electroactive Composites.

Electro-actuated polymer (EAP) can change its shape or volume under the action of an external electric field and shows similar behavioral characteristics with those of biological muscles, and so it has good application prospects in aerospace, bionic robots, and other fields. The properties of cellulose-based electroactive materials are similar to ionic EAP materials, although they have higher Young's modulus and lower energy consumption. However, cellulose-based electroactive materials have a more obvious deficiency-their actuation performance is often more significantly affected by ambient humidity due to the hygroscopicity caused by the strong hydrophilic structure of cellulose itself. Compared with cellulose, chitosan has good film-forming and water retention properties, and its compatibility with cellulose is very excellent. In this study, a chitosan/cellulose composite film doped with ionic liquid, 1-ethyl-3-methylimidazolium acetate ([EMIM]Ac), was prepared by co-dissolution and regeneration process using [EMIM]Ac as the solvent. After that, a conductive polymer, poly(3,4-ethylenedioxythiophene)/poly (styrene sulfonate) (PEDOT: PSS), was deposited on the surface of the resulted composite, and then a kind of cellulose-based electroactive composites were obtained. The results showed that the end bending deformation amplitude of the resulted material was increased by 2.3 times higher than that of the pure cellulose film under the same conditions, and the maximum deformation amplitude reached 7.3 mm. The tensile strength of the chitosan/cellulose composite film was 53.68% higher than that of the cellulose film, and the Young's modulus was increased by 72.52%. Furthermore, in comparison with the pure cellulose film, the water retention of the composite film increased and the water absorption rate decreased obviously, which meant that the resistance of the material to changes in environmental humidity was greatly improved.

CNS involvement in CMTX1 caused by a novel connexin 32 mutation: a 6-year follow-up in neuroimaging and nerve conduction.

X-linked Charcot-Marie-Tooth disease, type 1 (CMTX1) is one of the most common inherited neurological disorders. Obvious CNS involvement is relatively rare in CMTX1 patients. A 24-year-old male with CMTX1 presented with three transient stroke-like attacks, and was followed up regularly for 6 years with brain MRI and electrophysiological examination. Transient symmetrical high signals on T2 imaging and restricted diffusion were found in bilateral deep white matter. Electrophysiological measurement revealed a sensorimotor peripheral neuropathy with slightly reduced nerve conduction velocities. A novel thymine to cytosine mutation at nucleotide position 445 in the connexin 32 allele of the GJB1 gene was identified. During the 6-year longitudinal study, patient's motor and sensory function did not worsen; radiological abnormalities correlated with episodes of CNS dysfunction and resolved after clinical recovery; electrophysiological records showed no obvious change. Little change in the patient's clinical, radiological and electrophysiological results over the follow-up reflected a slow disease progression.

Multifunctional three-dimensional macroporous nanoelectronic networks for smart materials.

Seamless and minimally invasive integration of 3D electronic circuitry within host materials could enable the development of materials systems that are self-monitoring and allow for communication with external environments. Here, we report a general strategy for preparing ordered 3D interconnected and addressable macroporous nanoelectronic networks from ordered 2D nanowire nanoelectronic precursors, which are fabricated by conventional lithography. The 3D networks have porosities larger than 99%, contain approximately hundreds of addressable nanowire devices, and have feature sizes from the 10-µm scale (for electrical and structural interconnections) to the 10-nm scale (for device elements). The macroporous nanoelectronic networks were merged with organic gels and polymers to form hybrid materials in which the basic physical and chemical properties of the host were not substantially altered, and electrical measurements further showed a >90% yield of active devices in the hybrid materials. The positions of the nanowire devices were located within 3D hybrid materials with ∼14-nm resolution through simultaneous nanowire device photocurrent/confocal microscopy imaging measurements. In addition, we explored functional properties of these hybrid materials, including (i) mapping time-dependent pH changes throughout a nanowire network/agarose gel sample during external solution pH changes, and (ii) characterizing the strain field in a hybrid nanoelectronic elastomer structures subject to uniaxial and bending forces. The seamless incorporation of active nanoelectronic networks within 3D materials reveals a powerful approach to smart materials in which the capabilities of multifunctional nanoelectronics allow for active monitoring and control of host systems.

The root-like chitosan nanofiber porous scaffold cross-linked by genipin with type I collagen and its osteoblast compatibility.

Bone tissue repair is difficult due to the dense structure of the extracellular matrix. To solve this problem, a porous chitosan nanofiber scaffold (CSNFS) with an extracellular matrix-like structure was prepared via a facile cross-linked reaction of root-like chitosan nanofiber (CSNF) and collagen (Col) by using genipin (Gen) as the cross-linker. The optimal preparation conditions of CSNFS is weight ratio of CSNF:Col:Gen =1:1:0.1, crosslinked 48 h under 37 °C. CSNFS shows high porosity with adequate micro-scale pores, and its BET data shows that there are a large number of nano-scale pores. The CSNFS mechanical strength is higher than that of the chitosan scaffold both in dry and wet state. MC3T3 cells grow well on CSNFS, can overgrow the scaffold in three-dimensional space, adhere and differentiate well within those nanofiber structure. The cross-linked CSNFS has good biocompatibility and can be used as a repair material for bone tissue engineering.

Organic Solvent-Free Preparation of Chitosan Nanofibers with High Specific Surface Charge and Their Application in Biomaterials.

The application of chitosan nanofibers in biological tissue-engineering materials has attracted wide attention. A novel and organic solvent-free method was developed for the fabrication of rootlike chitosan nanofibers (CSNFs) with diameters of 40-250 nm. This method includes three-step mechanical processing of swelling-beating-centrifugation or swelling-beating-homogenization. The obtained nanofibers showed high yields (>95%) and positive specific surface charges (up to +375 µeq/g) and could be uniformly dispersed in the aqueous phase. The unique fiber shape and the good length-to-diameter ratio of CSNFs endowed chitosan nanofiber paper (CSNFP) products with excellent mechanical properties, and the wet tensile strength of the CSNFPs was nearly five times higher than common chitosan films. In addition, the calvaria-derived preosteoblastic cells exhibited a higher adherence efficiency and proliferation on CSNFP than on chitosan films. The chitosan nanofiber scaffold products also benefited the attachment of preosteoblastic cells and allowed them to grow in three dimensions. This method has significant industrial potential for the industrialization of chitosan nanofibers, which may have broad applications in various biomaterials.