title: Direct-write fabrication of functional protein matrixes using a low-cost Q-switched laser.
abstract: We report the use of an inexpensive, small, and "turn-key" Q-switched 532-nm Nd:YAG laser as a source for nonlinear, direct-write protein microfabrication. In this approach, microJoule pulses (pulse widths, approximately 600 ps) are focused using high numerical aperture optics to submicrometer focal spots, creating instantaneous intensities great enough to promote multiphoton excitation of a photosensitizer and subsequent intermolecular cross-linking of protein molecules. By scanning the femtoliter focal volume through reagent solution, extended protein-based structures can be fabricated with precise, three-dimensional topographies. As with earlier studies using a femtosecond titanium:sapphire laser costing more than 100K, physically robust and chemically responsive microstructures can be fashioned rapidly with feature sizes smaller than 0.5 microm, and cross-linking can be achieved using both biologically benign sensitizers (e.g., flavins) and by using the proteins themselves to sensitize cross-linking. We demonstrate in situ fabrication to corral neurite outgrowth and show the ability to functionalize avidin structures with biotinylated reagents, an approach that enables chemical sensing to be performed in specified microenvironments. Characterization of this inexpensive, low-power source will greatly broaden access to direct-write protein microfabrication.
authors.affiliation: Department of Chemistry and Biochemistry and the Institute for Cellular & Molecular Biology, 1 University Station A5300, University of Texas, Austin, Texas 78712, USA.
authors.forename: Bryan
authors.initials: B
authors.lastname: Kaehr
authors.forename: Nusret
authors.initials: N
authors.lastname: Ertas
authors.forename: Rex
authors.initials: R
authors.lastname: Nielson
authors.forename: Richard
authors.initials: R
authors.lastname: Allen
authors.forename: Ryan T
authors.initials: RT
authors.lastname: Hill
authors.forename: Matthew
authors.initials: M
authors.lastname: Plenert
authors.forename: Jason B
authors.initials: JB
authors.lastname: Shear
mesh_terms: D000818:Animals; D001360:Avidin / Q000032:analysis*; D005109:Extracellular Matrix / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007834:Lasers; D011506:Proteins / Q000737:chemistry*; D051381:Rats; D012680:Sensitivity and Specificity
chemical_list: D011506:Proteins; D001360:Avidin