Fabrication Of Low-dimensional Micro/Nano Functional Materials With Electrospinning And Exploration Of Their Potential Applications

Electrospinning is a kind of technique that applying high electric field for fabrication of one-dimensional nano/micro materials. Compared to parallel techniques, electrospinning possesses a lot of priorities. For example, it's simpler, more cost-effective, more smarter, more flexible, and more productive, etc. This technique, by now, is reckoned as the only promising approach for industrial fabrication of continuously long nano/micro fibers.In this investigation, based on electrospinning technique combined with other methods, we fabricated various kinds of functional nano/micro fibers and explored their potential applications in many fields. Our main investigations focused on the following aspects:We made an investigation on the craft for synthesis of spinnable SiO2 sol through the sol-gel method, and studied the influence from the property of SiO2 sol to the morphology and size of the electrospun products. The results indicated that spinnability of the SiO2 seriously relies on its reaction time and variation of electrospinning parameters have great influence on the morphology and size of the SiO2 products. The electrospun SiO2 nanofiber obtained from sol-gel derived SiO2 possesses high flexibility.Using the above SiO2 electrospun fiber as substrate, we grafted silver nanoparticles on fiber surface through post incubation in silver nitrate solution to obtain silver nanoparticles decorated SiO2 nanofiber. It was found that size and shape of the grafted silver nanoparticles are tremendously affected by the solution concentration and the incubation temperature and time. We investigated the antibacterial effect of this composite inorganic nanofiber and the results demonstrated this material possesses efficient antibacterial ability. In addition, cytotoxicity investigation proved that this material is highly biocompatible, it can effectively promote the proliferation and viability of bone marrow mesenchymal stem cells. Simply through calcinations, the used naofibers can be renewed to possess reusability. Consequently, we believe this material is suitable to be applied as reusable wound cover.Through addition of silver nitrate in SiO2 sol, we prepared silver-doped core-shell structured mesoporous SiO2 nanofiber with electrospinning and modified Stober method, and investigated its potential as advanced wound cover. Our investigation indicated that the core-shell mesoporous SiO2 fiber possesses high flexibility and huge specific surface area, it can absorb water and simulated body fluid with a big capacity. In addition, this material can slowly release antibacterial reagent silver to provide long-term antibacterial effect, while its mesoporous shell can accommodate and release drugs with a relatively fast mode. Consequently, the core-shell mesoporous SiO2 fiber possesses dual drug-releasing profiles (Sustained release of antibacterial reagent and fast release of anesthetic drug) and maintain moderate moist environment to promote recover of damaged skin, thus is very suitable to be applied as wound cover.Similarly, with the above electrospun SiO2 nanofiber as soft template, we fabricated mesoporous SiO2 fiber with core-shell architecture through modified Stober method and subsequent calcinations. We investigated the potential of this material as efficient adsorbent for removal of heavy metal ions from water. Our investigation revealed that the mesoporous SiO2 fiber can adsorb Pb2+ and Cd2+ with a rapid speed and a big capacity. In addition, adsorption capability of this material can be further improved through grafting of thiol groups on fiber surface. Benefiting from its high flexibility, the mesoporous SiO2 fiber can be conveniently patterned into nonwoven film with desired shapes, thus simplify the adsorption process and enhance the feasibility of this material for industrial applications.Nanoporous structure in bioactive glass fibers is quite beneficial to improve their bioactivity. However, it is very difficult to obtain high bioactivity and good mechanical strength simultaneously. In this investigation, we propose a strategy for development of novel submicron bioactive glass fibers which show both high bioactivity and excellent mechanical strength by employing core-shell mesoporous architecture. We further explored multifunctions of the obtained materials, including drug-loading and controllable releasing ability, and antibacterial effect. Our results demonstrated that the core-shell structured glass fiber possesses both high bioactivity and excellent mechanical strength. It can load ibuprofen (a kind of anesthetic drug) with a big capacity, and release this drug in simulated body fluid with a relatively fast speed. Silver nanoparticles in the condensed fiber core endows this material with persistent antibacterial effect. With these biological multifunctions, this mesoporous bioactive glass fiber could be an ideal material as hard tissue engineering scaffold. Recently, considerable investigations have been devoted to preparation of drug carriers with luminescent property, in order to track and monitor the release of the drugs. Nevertheless, most of the relevant works haven't really optimized the excitation and/or emission wavelength of the luminescent drug carriers into the so called human "NIR optical window", thus restrained the practical applications. Here, we proposed a novel strategy to fabricate porous YAG:Nd3+ nanofibers with excitation and emission both in the "NIR optical window" as luminescent drug carrier.The results indicated that the YAG:Nd3+ fiber possesses a fine irregularly porous fibrous morphology with an average diameter of 378 nm. The 1064 nm emission of the sample can be excited in a wide range of waveband in the NIR region. During the release process of ibuprofen in simulated body fluid, along with the dissolving of the drug, the solvent enters into the pores, and the 1064 nm emission intensity of the YAG:Nd3+ fibers decreases gradually, due to the quenching effect of the hydroxyl groups, thus provides an approach to track and monitor the release of drugs. In addition, cytotoxicity investigation revealed that this YAG:Nd3+ nanofiber is biocompatible with human cells. Consequently, the porous YAG:Nd3+ nanofiber could be a kind of promising material as advanced drug carrier.As an extension for the investigation of Ag-SiO2 based antibacterial material with electrospinning, we fabricated silver nanoparticles doped SiO2 microsphere with electrospraying technique, and evaluated its antibacterial effect, silver nanoparticles are not only doped inside, but also embedded on the surface of SiO2 microsphere, making the sample appear like strawberries. Our investigation revealed that the electrosprayed Ag-SiO2 microsphere is environmental stable and washing resistant, its antibacterial effect is very efficient and long-lasting.