Browsing by Author "Zhu, Ye"

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    Identification of Novel Short BaTiO3-Binding/Nucleating Peptides for Phage-Templated in Situ Synthesis of BaTiO3 Polycrystalline Nanowires at Room Temperature
    (American Chemical Society, 2016) Li, Yan; Cao, Binrui; Yang, Mingying; Zhu, Ye; Suh, Junghae; Mao, Chuanbin; Bioengineering
    Ferroelectric materials, such as tetragonal barium titanate (BaTiO3), have been widely used in a variety of areas including bioimaging, biosensing, and high power switching devices. However, conventional methods for the synthesis of tetragonal phase BaTiO3 usually require toxic organic reagents and high temperature treatments, and are thus not environment-friendly and energy-efficient. Here, we took advantage of the phage display technique to develop a novel strategy for the synthesis of BaTiO3 nanowires. We identified a short BaTiO3-binding/nucleating peptide, CRGATPMSC (named RS), from a phage-displayed random peptide library by biopanning technique and then genetically fused the peptide to the major coat protein (pVIII) of filamentous M13 phages to form the pVIII-RS phages. We found that the resultant phages could not only bind with the presynthesized BaTiO3 crystals but also induce the nucleation of uniform tetragonal BaTiO3 nanocrystals at room temperature and without the use of toxic reagents to form one-dimensional polycrystalline BaTiO3 nanowires. This approach enables the green synthesis of BaTiO3 polycrystalline nanowires with potential applications in bioimaging and biosensing fields.
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    Rapid fabrication of hydrogel micropatterns by projection stereolithography for studying self-organized developmental patterning
    (Public Library of Science, 2021) Zhu, Ye; Sazer, Daniel; Miller, Jordan S.; Warmflash, Aryeh; Bioengineering; Biosciences
    Self-organized patterning of mammalian embryonic stem cells on micropatterned surfaces has previously been established as an in vitro platform for early mammalian developmental studies, complimentary to in vivo studies. Traditional micropatterning methods, such as micro-contact printing (μCP), involve relatively complicated fabrication procedures, which restricts widespread adoption by biologists. Here, we demonstrate a rapid method of micropatterning by printing hydrogel micro-features onto a glass-bottomed culture vessel. The micro-features are printed using a projection stereolithography bioprinter yielding hydrogel structures that geometrically restrict the attachment of cells or proteins. Compared to traditional and physical photomasks, a digitally tunable virtual photomask is used in the projector to generate blue light patterns that enable rapid iteration with minimal cost and effort. We show that a protocol that makes use of this method together with LN521 coating, an extracellular matrix coating, creates a surface suitable for human embryonic stem cell (hESC) attachment and growth with minimal non-specific adhesion. We further demonstrate that self-patterning of hESCs following previously published gastrulation and ectodermal induction protocols achieves results comparable with those obtained with commercially available plates.
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    Rapid Hydrogel Micropatterning and Cadherin Switching: Insights into Developmental Patterning and Mesendodermal Trajectories in Human Embryonic Stem Cells
    (2024-12-06) Zhu, Ye; Warmflash, Aryeh
    This thesis comprises two parts, each contributing novel insights into self-organized patterning and differentiation in human pluripotent stem cells (hPSCs). Self-organized patterning of mammalian pluripotent stem cells on micropatterned surfaces has been established as an in vitro platform for early developmental studies, complementary to in vivo animal models. The first project addressed the limitations of current micropatterning techniques, due to complex fabrication processes, such as micro-contact printing, preventing widespread usage in biological research. We developed a projection stereolithography-based micropatterning method that uses a digitally tunable photomask to rapidly print hydrogel with micro-features onto glass-bottomed-culture vessels. Combined with the laminin-521 (or LN521) extracellular matrix coating, this technology provides a surface suitable for hPSC attachment and growth with minimal non-specific cell adhesion. The study demonstrated the self-patterning results of hPSCs following gastrulation and ectodermal induction produced on our micropatterned surface are comparable with those obtained using commercially available micropatterned plates. This novel micropatterning approach enables customizable, rapid fabrication of micropatterned surfaces for cell study at a reduced cost, with potential application in developmental biology and regenerative medicine research. The second project explores cadherin switching during the epithelial-mesenchymal transition (EMT) in the differentiation trajectory of hPSCs through the primitive streaks (PS) and into mesodendermal subtypes. We measured EMT, and cadherin switching (E-cadherin downregulation and N-cadherin upregulation) during hPSC differentiation to PS and subsequently to distinct mesendodermal subtypes using established protocols and variants in signaling modulation of the key pathways, i.e., Activin, BMP, and Wnt. The findings reveal that while early signaling perturbations largely affected the extent of cadherin switching, the differentiation potential of PS cells was unimpacted. Specifically, definitive endoderm progenitors retained the ability to differentiate into both endodermal and mesodermal fates, while PS cells in mid to posterior regions exhibited restricted potential toward definitive endoderm. Additionally, E-Cadherin knockout did not alter cell fate outcomes in mesendodermal differentiation. Overall, the project revealed the decoupling of cadherin dynamics from cell fate decisions in mesendodermal differentiation through PS coordinates, with translational potential for cancer and age-related degenerative disease studies, where modulating EMT and cadherin switching could support innovative therapy development.