ABSTRACT
Janus particles (JPs) have attracted increasing attention from the communities of materials science, chemistry, physics, and biology. However, the nanoscale JPs that can switch shapes in response to an environmental stimulus is a significant challenge. In this article, we have demonstrated a simple procedure to fabricate the amphipathic Janus nanoparticles (JNPs) composed of hydrophilic body and hydrophobic lobe via using sudden negative pressure technique. Moreover, in response to temperature, the nanoparticles can recover to their initial nanosphere state by a switchable process, showing promising shape memory effect. Here, we can monitor the switchable nanostructures with hydrophilic and hydrophobic changes in the shape memory process of the JNPs by transmission electron microscope, dynamic light scattering, and water contact angle. Furthermore, we successfully compare the differences in shape deformation ratio and shape recovery ratio using the three test methods by the statistical analysis of Student's t-test for independent samples. In addition, we also develop hybrid magnetic Janus nanoparticles, changed from the amphipathic JNPs by the selective attachment of magnetic nanoparticles with hydrophobic molecules, which show new Janus nanostructure and shape memory property.
ABSTRACT
Electrical stimulation in biology and gene expression has attracted considerable attention in recent years. However, it is inconvenient that the electric stimulation needs to be supplied an implanted power-transported wire connecting the external power supply. Here, we fabricated a self-powered composite nanofiber (CNF) and developed an electric generating system to realize electrical stimulation based on the electromagnetic induction effect under an external rotating magnetic field. The self-powered CNFs generating an electric signal consist of modified MWNTs (m-MWNTs) coated Fe3O4/PCL fibers. Moreover, the output current of the nanocomposites can be increased due to the presence of the magnetic nanoparticles during an external magnetic field is applied. In this paper, these CNFs were employed to replace a bullfrog's sciatic nerve and to realize the effective functional electrical stimulation. The cytotoxicity assays and animal tests of the nanocomposites were also used to evaluate the biocompatibility and tissue integration. These results demonstrated that this self-powered CNF not only plays a role as power source but also can act as an external power supply under an external rotating magnetic field for noninvasive the replacement of injured nerve.
ABSTRACT
Molecular self-assembly has emerged as a powerful technique for controlling the structure and properties of core/shell structured supraparticles. However, drug-loading capacities and therapeutic effects of self-assembled magnetic core/shell nanocarriers with magnetic nanoparticles in the core are limited by the intervention of the outer organic or inorganic shell, the aggregation of superparamagnetic nanoparticles, the narrowed inner cavity, etc. Here, we present a self-assembly approach based on rebalancing hydrogen bonds between components under a supercooling process to form a new core/shell nanoscale supraparticle with magnetic nanoparticles as the shell and a polysaccharide as a core. Compared with conventional iron oxide nanoparticles, this magnetic shelled core/shell nanoparticle possesses an optimized inner cavity and a loss-free outer magnetic property. Furthermore, we find that the drug-loaded magnetic shelled nanocarriers showed interesting in vitro release behaviors at different pH conditions, including "swelling-broken", "dissociating-broken", and "bursting-broken" modes. Our experiments demonstrate the novel design of the multifunctional hybrid nanostructure and provide a considerable potential for the biomedical applications.
ABSTRACT
Preparation of nanoscale Janus particles that can respond to external stimulation and, at the same time, be prepared using an easily achievable method presents a significant challenge. Here, we have demonstrated the shape memory of Janus nanoparticles (SMJNPs) with a multifunctional combination of Janus nanostructure and a shape memory effect, composed of a well-defined amphipathic sucrose-poly(ε-caprolactone) cross-linked network. A sudden negative pressure method was first used to prepare the Janus-shaped nanoparticles (temporary shape), which can switch their shape and wettability. The Janus-shaped nanoparticle is an amphipathic structure composed of hydrophilic and hydrophobic parts. Moreover, in response to temperature, the nanoparticle can recover their nanosphere state via a shape memory process. The novel Janus nanoparticles with the shape memory property also show a great potential for application such as drug delivery.