Owing to the characteristics of mimicking human skin's function and transmitting sensory signals, electronic skin (eskin), as an emerging and exciting research field, has inspired tremendous efforts in the biomedical field. However, it is frustrating that most e-skins are prone to bacterial infections, resulting a serious threat to human health. Therefore, the construction of e-skin with an integrated perceptual signal and antibacterial properties is highly desirable. Herein, the dynamic supramolecular hydrogel was prepared through a freezing/thawing method by cross-linking the conductive graphene (G), biocompatible polyvinyl alcohol (PVA), self-adhesive polydopamine (PDA), and in situ formation antibacterial silver nanoparticles (AgNPs). Having fabricated the hierarchical network structure, the PVA−G−PDA−AgNPs composite hydrogel with a tensile strength of 1.174 MPa and an elongation of 331% paves way for flexible e-skins. Notably, the PVA−G−PDA−AgNPs hydrogel exhibits outstanding antibacterial activity to typical pathogenic microbes (e.g., Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus), which effectively prevents bacterial infections that harm human health. With self-adhesiveness to various surfaces and excellent conductivity, the PVA−G−PDA−AgNPs composite hydrogel was used as strain sensors to detect a variety of macroscale and microscale human motions successfully. Meanwhile, the excellent rehealing property allows the hydrogel to recycle as a new sensor to detect large-scale human activities or tiny movement. Based on these remarkable features, the antibacterial, self-adhesive, recyclable, and tough conductive composite hydrogels possess the great promising application in biomedical materials.
Wound dressing, which can release anti-infectives in a controlled way, is taking an important role in the treatment and recovery of the open wound. An adequate release of antibiotics can prevent infections from microorganisms effectively. Among the new candidates of fabricating base materials for wound dressing, electrospinning fiber mats are attracting numerous attentions for their excellent performance in controlled drug delivery. The drug release behavior of electrospinning fiber mats can be tuned by changing the chemical components and the geometric structures of the mats. In this study, fiber mats with different geometric structures, which composed of poly-εcaprolactone (PCL), polyethylene glycol (PEG), and ciprofloxacin (Cip) with different blending ratios, were successfully fabricated by direct-writing melt electrospinning, and the release behavior of Cip were subsequently investigated in vitro. The results showed that the addition of PEG improved the hydrophilicity of the mats, which in turn affected the manner of drug release. The presence of PEG changed the releasing mechanism from a non-Fickian diffusion into Fickian diffusion, which indicated that the diffusion of Cip from the composite fiber mats became the main factor of drug release instead of polymer degradation. Besides, with the same composition but different geometric structures, the drug release behavior is of significant difference. Therefore, all the Cip-loaded composite fiber mats showed antibacterial activities but with different efficiency. In summary, the release of the drug could be controlled by adding PEG and changing the geometric structures according to the different requirement of wound dressings.
Proteins
are like miracle machines, playing important roles in
living organisms. They perform vital biofunctions by further combining
together and/or with other biomacromolecules to form assemblies or
condensates such as membraneless organelles. Therefore, studying the
self-assembly of biomacromolecules is of fundamental importance. In
addition to their biological activities, protein assemblies also exhibit
extra properties that enable them to achieve applications beyond their
original functions. Herein, this study showed that in the presence
of monosaccharides, ethylene glycols, and amino acids, β-lactoglobulin
(β-LG) can form assemblies with specific structures, which were
highly reproducible. The mechanism of the assembly process was studied
through multi-scale observations and theoretical analysis, and it
was found that the assembling all started from the formation of solute-rich
liquid droplets via liquid–liquid phase separation (LLPS).
These droplets then combined together to form condensates with elaborate
structures, and the condensates finally evolved to form assemblies
with various morphologies. Such a mechanism of the assembly is valuable
for studying the assembly processes that frequently occur in living
organisms. Detailed studies concerning the properties and applications
of the obtained β-LG assemblies showed that the assemblies exhibited
significantly better performances than the protein itself in terms
of autofluorescence, antioxidant activity, and metal ion absorption,
which indicates broad applications of these assemblies in bioimaging,
biodetection, biodiagnosis, health maintenance, and pollution treatment.
This study revealed that biomacromolecules, especially proteins, can
be assembled via LLPS, and some unexpected application potentials
could be found beyond their original biological functions.
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