title: Directing polyallylamine adsorption on microlens array patterned silicon for microarray fabrication.
abstract: The selective adsorption of reagents is often essential for bioarray and lab-on-a-chip type devices. As the starting point for a bioarray, alkyl monolayer terminated silicon shards were photopatterned in a few nanoseconds with thousands of wells (spots) using an optical element, a microlens array. Polyallylamine (PAAm), a primary amine containing polymer, adsorbed with little selectivity to the spots, i.e., silicon oxide, over the hydrophobic background. However, at appropriate concentrations, addition of a cationic surfactant to the PAAm deposition solution, cetyltrimethylammonium chloride, prevented the nonspecific adsorption of PAAm onto the hydrophobic monolayer, while directing it effectively to the active spots on the device. A nonionic surfactant was less effective in preventing the nonspecific adsorption of PAAm onto the hydrophobic monolayer. The localized reactions/interactions of adsorbed PAAm with four species that are useful for bioconjugate chemistry: glutaric anhydride, phenylenediisothiocyanate, biotin NHS ester, and an oligonucleotide (DNA) were shown in the spots of an array. The reactivity of PAAm was further demonstrated with an isocyanate. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) played an important role in confirming selective surface reactivity and adsorption. X-ray photoelectron spectroscopy (XPS), spectroscopic ellipsometry, and wetting confirmed PAAm reactivity on planar substrates.
authors.affiliation: Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602, USA.
authors.forename: Gaurav
authors.initials: G
authors.lastname: Saini
authors.forename: Richard
authors.initials: R
authors.lastname: Gates
authors.forename: Matthew C
authors.initials: MC
authors.lastname: Asplund
authors.forename: Steve
authors.initials: S
authors.lastname: Blair
authors.forename: Sachin
authors.initials: S
authors.lastname: Attavar
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Linford
mesh_terms: D000327:Adsorption; D057927:Hydrophobic and Hydrophilic Interactions; D046228:Microarray Analysis / Q000295:instrumentation / Q000379:methods*; D055616:Microtechnology / Q000379:methods*; D011073:Polyamines / Q000737:chemistry*; D012825:Silicon / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry; D013057:Spectrum Analysis; D013499:Surface Properties
chemical_list: D011073:Polyamines; C063994:polyallylamine; D012822:Silicon Dioxide; D012825:Silicon