1666 wileyonlinelibrary.com Artifi cial micro-/nanoswimmers have various potential applications including minimally invasive diagnosis and targeted therapies, environmental sensing and monitoring, cell manipulation and analysis, and lab-on-a-chip devices. Inspired by natural motile bacteria such as E. Coli , artifi cial bacterial fl agella (ABFs) are one kind of magnetic helical microswimmers. ABFs can perform 3D navigation in a controllable fashion with micrometer precision under low-strength rotating magnetic fi elds (<10 mT) and are promising tools for targeted drug delivery in vitro and in vivo. In this work, the successful wirelessly targeted and single-cell gene delivery to human embryonic kidney (HEK 293) cells using ABFs loaded with plasmid DNA (pDNA) in vitro is demonstrated for the fi rst time. The ABFs are functionalized with lipoplexes containing pDNA to generate functionalized ABFs (f-ABFs). The f-ABFs are steered wirelessly by low-strength rotating magnetic fi elds and deliver the loaded pDNA into targeted cells. The cells targeted by f-ABFs are successfully transfected by the transported pDNA and expressed the encoding protein. These f-ABFs may also be useful for in vivo gene delivery and other applications such as sensors, actuators, cell biology, and lab-on-a-chip environments.
Degrapol ® and PLGA electrospun fiber fleeces were characterized with regard to fiber diameter, alignment, mechanical properties as well as scaffold porosity. The study showed that electrospinning parameters affect fiber diameter and alignment in an inverse relation: fiber diameter was increased with increased flow rate, with decrease in working distance and collector velocity, whereas fiber alignment increased with the working distance and collector velocity but decreased with increased flow rate. When Degrapol ® or PLGA-polymers were co-spun with increasing ratios of a water-soluble polymer that was subsequently removed; fibrous scaffolds with increased porosities were obtained. Mechanical properties correlated with fiber alignment rather than fiber diameter as aligned fiber scaffolds demonstrated strong mechanical anisotropy. For co-spun fibers the Young's modulus correlated inversely with the amount of co-spun polymer. Cell proliferation was independent of the porosity of the scaffold, but different between the two polymers. Furthermore, fibrous scaffolds with different porosities were analyzed for cell infiltration suggesting that cell infiltration was enhanced with increased porosity and increasing time. These experiments indicate that 3D-fiber fleeces can be produced with controlled properties, being prerequisites for successful scaffolds in tissue engineering applications.
Functionalizing nanoparticles with cell-penetrating peptides is a popular choice for cellular delivery. We investigated the effects of TAT peptide concentration and arrangement in solution on functionalized nanoparticles' efficacy for membrane permeation. We found that cell internalization correlates with the positive charge distribution achieved prior to nanoparticle encountering interactions with membrane. We identified a combination of solution based properties required to maximize the internalization efficacy of TAT-functionalized nanoparticles.
Control of pH gradient profile at the electrode-electrolyte interfaces allows the control of the enzymatic PEG-hydrogel polymerization. By tuning the solution pH, buffer capacity, and the applied current, the extent of the local inhibition and confinement of the Factor XIII-mediated polymerization of PEG are controlled. This technology opens new perspectives for the production of 3D-structured biological microenvironments.
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