title: Efficient biofunctionalization of polysilicon barcodes for adhesion to the zona pellucida of mouse embryos.
abstract: Cell tracking is an emergent area in nanobiotechnology, promising the study of individual cells or the identification of populations of cultured cells. In our approach, microtools designed for extracellular tagging are prepared, because using biofunctionalized polysilicon barcodes to tag cell membranes externally avoids the inconveniences of cell internalization. The crucial covalent biofunctionalization process determining the ultimate functionality was studied in order to find the optimum conditions to link a biomolecule to a polysilicon barcode surface using a self-assembled monolayer (SAM) as the connector. Specifically, a lectin (wheat germ agglutinin, WGA) was used because of its capacity to recognize some specific carbohydrates present on the surface of most mammalian cells. Self-assembled monolayers were prepared on polysilicon surfaces including aldehyde groups as terminal functions to study the suitability of their covalent chemical bonding to WGA. Some parameters, such as the polysilicon surface roughness or the concentration of WGA, proved to be crucial for successful biofunctionalization and bioactivity. The SAMs were characterized by contact angle measurements, time-of-flight secondary ion mass spectrometry (TOF-SIMS), laser desorption/ionization time-of-flight mass spectrometry (LDI-TOF MS), and atomic force microscopy (AFM). The biofunctionalization step was also characterized by fluorescence microscopy and, in the case of barcodes, by adhesion experiments to the zona pellucida of mouse embryos. These experiments showed high barcode retention rates after 96 h of culture as well as high embryo viability to the blastocyst stage, indicating the robustness of the biofunctionalization and, therefore, the potential of these new microtools to be used for cell tagging.
authors.affiliation: Department of Pharmacology and Therapeutical Chemistry and Institute of Nanoscience and Nanotechnology UB (IN2UB),  Universitat de Barcelona , Avda. Joan XXIII s/n, 08028 Barcelona, Spain.
authors.forename: Oriol
authors.initials: O
authors.lastname: Penon
authors.forename: Sergi
authors.initials: S
authors.lastname: Novo
authors.forename: Sara
authors.initials: S
authors.lastname: Durán
authors.forename: Elena
authors.initials: E
authors.lastname: Ibañez
authors.forename: Carme
authors.initials: C
authors.lastname: Nogués
authors.forename: Josep
authors.initials: J
authors.lastname: Samitier
authors.forename: Marta
authors.initials: M
authors.lastname: Duch
authors.forename: José Antonio
authors.initials: JA
authors.lastname: Plaza
authors.forename: Lluïsa
authors.initials: L
authors.lastname: Pérez-García
mesh_terms: D000818:Animals; D058948:Cell Tracking / Q000379:methods*; D002478:Cells, Cultured; D003433:Crosses, Genetic; D004622:Embryo, Mammalian; D005260:Female; D051379:Mice; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D018625:Microscopy, Atomic Force; D008856:Microscopy, Fluorescence; D058105:Polymerization; D012825:Silicon / Q000737:chemistry*; D018629:Spectrometry, Mass, Secondary Ion; D013194:Staining and Labeling / Q000379:methods*; D013499:Surface Properties; D014909:Wheat Germ Agglutinins / Q000737:chemistry*; D015044:Zona Pellucida / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure
chemical_list: D014909:Wheat Germ Agglutinins; D012825:Silicon