title: Enhanced microcontact printing of proteins on nanoporous silica surface.
abstract: We demonstrate porous silica surface modification, combined with microcontact printing, as an effective method for enhanced protein patterning and adsorption on arbitrary surfaces. Compared to conventional chemical treatments, this approach offers scalability and long-term device stability without requiring complex chemical activation. Two chemical surface treatments using functionalization with the commonly used 3-aminopropyltriethoxysilane (APTES) and glutaraldehyde (GA) were compared with the nanoporous silica surface on the basis of protein adsorption. The deposited thickness and uniformity of porous silica films were evaluated for fluorescein isothiocyanate (FITC)-labeled rabbit immunoglobulin G (R-IgG) protein printed onto the substrates via patterned polydimethlysiloxane (PDMS) stamps. A more complete transfer of proteins was observed on porous silica substrates compared to chemically functionalized substrates. A comparison of different pore sizes (4-6 nm) and porous silica thicknesses (96-200 nm) indicates that porous silica with 4 nm diameter, 57% porosity and a thickness of 96 nm provided a suitable environment for complete transfer of R-IgG proteins. Both fluorescence microscopy and atomic force microscopy (AFM) were used for protein layer characterizations. A porous silica layer is biocompatible, providing a favorable transfer medium with minimal damage to the proteins. A patterned immunoassay microchip was developed to demonstrate the retained protein function after printing on nanoporous surfaces, which enables printable and robust immunoassay detection for point-of-care applications.
authors.affiliation: Department of Biomedical Engineering, University of Texas at Austin, Austin, TX 78758, USA.
authors.forename: Ellen
authors.initials: E
authors.lastname: Blinka
authors.forename: Kathryn
authors.initials: K
authors.lastname: Loeffler
authors.forename: Ye
authors.initials: Y
authors.lastname: Hu
authors.forename: Ashwini
authors.initials: A
authors.lastname: Gopal
authors.forename: Kazunori
authors.initials: K
authors.lastname: Hoshino
authors.forename: Kevin
authors.initials: K
authors.lastname: Lin
authors.forename: Xuewu
authors.initials: X
authors.lastname: Liu
authors.forename: Mauro
authors.initials: M
authors.lastname: Ferrari
authors.forename: John X J
authors.initials: JX
authors.lastname: Zhang
mesh_terms: D000327:Adsorption; D000818:Animals; D016650:Fluorescein-5-isothiocyanate; D007118:Immunoassay; D007074:Immunoglobulin G / Q000378:metabolism*; D018625:Microscopy, Atomic Force; D058608:Nanopores / Q000648:ultrastructure; D036103:Nanotechnology / Q000379:methods*; D009584:Nitrogen / Q000737:chemistry; D010316:Particle Size; D020442:Poloxamer / Q000737:chemistry; D011817:Rabbits; D012822:Silicon Dioxide / Q000737:chemistry*; D013499:Surface Properties; D014961:X-Ray Diffraction
chemical_list: D007074:Immunoglobulin G; D020442:Poloxamer; D012822:Silicon Dioxide; D016650:Fluorescein-5-isothiocyanate; D009584:Nitrogen