title: Aptamer-functionalized hydrogel microparticles for fast visual detection of mercury(II) and adenosine.
abstract: With a low optical background, high loading capacity, and good biocompatibility, hydrogels are ideal materials for immobilization of biopolymers to develop optical biosensors. We recently immobilized mercury and lead binding DNAs within a monolithic gel and demonstrated ultrasensitive visual detection of these heavy metals. The high sensitivity was attributed to the enrichment of the analytes into the gels. The signaling kinetics was slow, however, taking about 1 h to obtain a stable optical signal because of a long diffusion distance. In this work, we aim to understand the analyte enrichment process and improve the signaling kinetics by preparing hydrogel microparticles. DNA-functionalized gel beads were synthesized using an emulsion polymerization technique and most of the beads were between 10 and 50 μm. Acrydite-modified DNA was incorporated by copolymerization. Visual detection of 10 nM Hg(2+) was still achieved and a stable signal was obtained in just 2 min. The gel beads could be spotted to form a microarray and dried for storage. A new visual sensor for adenosine was designed and immobilized within the gel beads. The adenosine aptamer binds its target about 1000-fold less tightly compared to the mercury binding DNA, allowing a comparison to be made on analyte enrichment by aptamer-functionalized hydrogels.
authors.affiliation: Department of Chemistry, Waterloo Institute for Nanotechnology, University of Waterloo, Waterloo, Ontario, Canada.
authors.forename: Youssef
authors.initials: Y
authors.lastname: Helwa
authors.forename: Neeshma
authors.initials: N
authors.lastname: Dave
authors.forename: Romain
authors.initials: R
authors.lastname: Froidevaux
authors.forename: Azadeh
authors.initials: A
authors.lastname: Samadi
authors.forename: Juewen
authors.initials: J
authors.lastname: Liu
mesh_terms: D000241:Adenosine / Q000737:chemistry; D052157:Aptamers, Nucleotide / Q000138:chemical synthesis / Q000737:chemistry*; D015374:Biosensing Techniques / Q000295:instrumentation* / Q000379:methods; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate / Q000138:chemical synthesis / Q000737:chemistry*; D007700:Kinetics; D008628:Mercury / Q000737:chemistry*; D010316:Particle Size
chemical_list: D052157:Aptamers, Nucleotide; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D008628:Mercury; D000241:Adenosine