Janus films with controlled pore structures could be particularly important in diverse applications. There remains a challenge for simple, rapid and scalable fabrication methods to control Janus Balance including the thickness of the individual face as well as porosity and pore size. Here we report the electrofabrication of a porous Janus film with controlled Janus Balance from aminopolysaccharide chitosan under the salt effect.Sequential deposition of chitosan under programmable salt environment and electrochemical conditions enables construction of Janus films with precisely controlled Janus Balance. Bioactive partially-soluble CaP salts can also generate porous structure in Janus film. We specifically report that a chitosan/hydroxyl apatite composite Janus film can serve as an effective scaffold for guided bone regeneration. The dense layer functions to provide mechanical support and serves as a barrier for fibrous connective tissue penetration. The porous composite layer functions to provide the microenvironment for osteogenesis. In vivo studies using a rat calvarial defect model confirms the beneficial features of this Janus composite for guided bone regeneration. These results suggest the potential of electrofabrication as a simple and scalable platform technology to tune the self-organization of soft matter for a range of emerging applications.
Microbial
disinfection associated with medical device surfaces
has been an increasing need, and surface modification strategies such
as antibacterial coatings have gained great interest. Here, we report
the development of polydopamine-ferrocene (PDA-Fc)-functionalized
TiO2 nanorods (Ti-Nd-PDA-Fc) as a context-dependent antibacterial
system on implant to combat bacterial infection and hinder biofilm
formation. In this work, two synergistic antimicrobial mechanisms
of the PDA-Fc coating are proposed. First, the PDA-Fc coating is redox-active
and can be locally activated to release antibacterial reactive oxygen
species (ROS), especially ·OH in response to the acidic microenvironment
induced by bacteria colonization and host immune responses. The results
demonstrate that redox-based antimicrobial activity of Ti-Nd-PDA-Fc
offers antibacterial efficacy of over 95 and 92% against methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia
coli (E. coli), respectively. Second, the photothermal
effect of PDA can enhance the antibacterial capability upon near-infrared
(NIR) irradiation, with over 99% killing efficacy against MRSA and E. coli, and even suppress the formation of biofilm
through both localized hyperthermia and enhanced ·OH generation.
Additionally, Ti-Nd-PDA-Fc is biocompatible when tested with model
pre-osteoblast MC-3T3 E1 cells and promotes cell adhesion and spreading
presumably due to its nanotopographical features. The MRSA-infected
wound model also indicates that Ti-Nd-PDA-Fc with NIR irradiation
can effectively eliminate bacterial infection and suppress host inflammatory
responses. We believe that this study demonstrates a simple means
to create biocompatible redox-active coatings that confer context-dependent
antibacterial activities to implant surfaces.
While conventional material fabrication methods focus on form and strength to achieve function, the fabrication of material systems for emerging life science applications will need to satisfy a more subtle set of requirements. A common goal for biofabrication is to recapitulate complex biological contexts (e.g. tissue) for applications that range from animal-on-a-chip to regenerative medicine. In these cases, the material systems will need to: (i) present appropriate surface functionalities over a hierarchy of length scales (e.g. molecular features that enable cell adhesion and topographical features that guide differentiation); (ii) provide a suite of mechanobiological cues that promote the emergence of native-like tissue form and function; and (iii) organize structure to control cellular ingress and molecular transport, to enable the development of an interconnected cellular community that is engaged in cell signaling. And these requirements are not likely to be static but will vary over time and space, which will require capabilities of the material systems to dynamically respond, adapt, heal and reconfigure. Here, we review recent advances in the use of electrically based fabrication methods to build material systems from biological macromolecules (e.g. chitosan, alginate, collagen and silk). Electrical signals are especially convenient for fabrication because they can be controllably imposed to promote the electrophoresis, alignment, self-assembly and functionalization of macromolecules to generate
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