title: Multiphoton photochemical crosslinking-based fabrication of protein micropatterns with controllable mechanical properties for single cell traction force measurements.
abstract: Engineering 3D microstructures with predetermined properties is critical for stem cell niche studies. We have developed a multiphoton femtosecond laser-based 3D printing platform, which generates complex protein microstructures in minutes. Here, we used the platform to test a series of fabrication and reagent parameters in precisely controlling the mechanical properties of protein micropillars. Atomic force microscopy was utilized to measure the reduced elastic modulus of the micropillars, and transmission electron microscopy was used to visualize the porosity of the structures. The reduced elastic modulus of the micropillars associated positively and linearly with the scanning power. On the other hand, the porosity and pore size of the micropillars associated inversely and linearly with the scanning power and reagent concentrations. While keeping the elastic modulus constant, the stiffness of the micropillars was controlled by varying their height. Subsequently, the single cell traction forces of rabbit chondrocytes, human dermal fibroblasts, human mesenchymal stem cells, and bovine nucleus pulposus cells (bNPCs) were successfully measured by culturing the cells on micropillar arrays of different stiffness. Our results showed that the traction forces of all groups showed positive relationship with stiffness, and that the chondrocytes and bNPCs generated the highest and lowest traction forces, respectively.
authors.affiliation: Tissue Engineering Laboratory, Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong Special Administrative Region, China.
authors.forename: Ming Hui
authors.initials: MH
authors.lastname: Tong
authors.affiliation: Tissue Engineering Laboratory, Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong Special Administrative Region, China.
authors.forename: Nan
authors.initials: N
authors.lastname: Huang
authors.affiliation: Tissue Engineering Laboratory, Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong Special Administrative Region, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.affiliation: Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong Special Administrative Region, China.
authors.forename: Zhuo Long
authors.initials: ZL
authors.lastname: Zhou
authors.affiliation: Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong Special Administrative Region, China.
authors.forename: Alfonso Hing Wan
authors.initials: AH
authors.lastname: Ngan
authors.affiliation: Department of Biomedical Engineering, School of Medicine, Tsinghua University, Beijing, 100084, China.
authors.forename: Yanan
authors.initials: Y
authors.lastname: Du
authors.affiliation: Tissue Engineering Laboratory, Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong Special Administrative Region, China.
authors.forename: Barbara Pui
authors.initials: BP
authors.lastname: Chan
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D002417:Cattle; D002460:Cell Line; D055119:Elastic Modulus; D006801:Humans; D018625:Microscopy, Atomic Force; D036641:Microscopy, Fluorescence, Multiphoton / Q000295:instrumentation / Q000379:methods; D011506:Proteins / Q000737:chemistry*; D011817:Rabbits; D059010:Single-Cell Analysis
chemical_list: D011506:Proteins
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