title: Polymer microfluidic chips with integrated waveguides for reading microarrays.
abstract: A microfluidic chip with an integrated planar waveguide was fabricated in poly(methyl methacrylate), PMMA, using a single-step, double-sided hot-embossing approach. The waveguide was embedded in air on three sides, the solution being interrogated on the fourth. DNA probes were covalently attached to the waveguide surface by plasma activating the PMMA and the use of carbodiimide coupling chemistry. Successful hybridization events were read using evanescent excitation monitored by an imaging microscope, which offered high spatial resolution (2 microm) and a large field-of-view (20 mm diameter field-of-view), providing imaging of the entire array without scanning. The application of the microfluidic/waveguide assembly was demonstrated by detecting low abundant point mutations; insertion C mutations in BRCA1 genes associated with breast cancer were analyzed using a universal array coupled to an allele-specific ligation assay. DNA probes consisting of amine-terminated oligonucleotides were printed inside the microfluidic channel using a noncontact microspotter. Mutant and wild-type genomic DNAs of BRCA1 were PCR (polymerase chain reaction) amplified, with the amplicons subjected to ligation detection reactions (LDRs). LDR solutions were allowed to flow over the microarray positioned on the polymer waveguide with successful ligation events discerned through fluorescence signatures present at certain locations of the array. The microfluidic/waveguide assembly could detect polymorphisms present at <1% of the total DNA content.
authors.affiliation: Department of Chemistry, Center for Bio-Modular Multi-Scale Systems (CBM2), and Center for Advanced Microstructure and Devices (CAMD), Louisiana State University, Baton Rouge, Louisiana 70803, USA.
authors.forename: Feng
authors.initials: F
authors.lastname: Xu
authors.forename: Proyag
authors.initials: P
authors.lastname: Datta
authors.forename: Hong
authors.initials: H
authors.lastname: Wang
authors.forename: Sitanshu
authors.initials: S
authors.lastname: Gurung
authors.forename: Masahiko
authors.initials: M
authors.lastname: Hashimoto
authors.forename: Suying
authors.initials: S
authors.lastname: Wei
authors.forename: Jost
authors.initials: J
authors.lastname: Goettert
authors.forename: Robin L
authors.initials: RL
authors.lastname: McCarley
authors.forename: Steven A
authors.initials: SA
authors.lastname: Soper
mesh_terms: D001483:Base Sequence; D017931:DNA Primers; D019398:Genes, BRCA1; D044085:Microfluidics / Q000295:instrumentation*; D009154:Mutation; D020411:Oligonucleotide Array Sequence Analysis; D016133:Polymerase Chain Reaction; D011108:Polymers / Q000737:chemistry*
chemical_list: D017931:DNA Primers; D011108:Polymers