title: Enhancing the detection limit of nanoscale biosensors via topographically selective functionalization.
abstract: Nanoscale biosensors have remarkable theoretical sensitivities but often suffer from suboptimal limits of detection in practice. This is in part because the sensing area of nanoscale sensors is orders of magnitude smaller than the total device substrate. Current strategies to immobilize probes (capture molecules) functionalize both sensing and nonsensing regions, leading to target depletion and diminished limits of detection. The difference in topography between these regions on nanoscale biosensors offers a way to selectively address only the sensing area. We developed a bottom-up, topographically selective approach employing self-assembled poly(N-isopropylacrylamide) (PNIPAM) hydrogel nanoparticles as a mask to preferentially bind target to only the active sensing region of a photonic crystal (PhC) biosensor. This led to over an order of magnitude improvement in the limit of detection for the device, in agreement with finite element simulations. Since the sensing elements in many nanoscale sensors are topographically distinct, this approach should be widely applicable.
authors.affiliation: Department of Biomedical Engineering, ¶Department of Biochemistry and Biophysics and #Department of Dermatology, University of Rochester , Rochester, New York 14627, United States.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Lifson
authors.forename: Dhrubajyoti
authors.initials: D
authors.lastname: Basu Roy
authors.forename: Benjamin L
authors.initials: BL
authors.lastname: Miller
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry; D000888:Antibodies, Anti-Idiotypic / Q000032:analysis; D055910:Antibodies, Immobilized; D015374:Biosensing Techniques / Q000295:instrumentation* / Q000379:methods; D005456:Fluorescent Dyes; D006801:Humans; D020100:Hydrogels; D007074:Immunoglobulin G / Q000737:chemistry; D057230:Limit of Detection; D053758:Nanoparticles / Q000737:chemistry; D055620:Optical Phenomena; D012235:Rhodamines; D017655:Silicon Compounds / Q000737:chemistry
chemical_list: D000180:Acrylic Resins; D000888:Antibodies, Anti-Idiotypic; D055910:Antibodies, Immobilized; D005456:Fluorescent Dyes; D020100:Hydrogels; D007074:Immunoglobulin G; D012235:Rhodamines; D017655:Silicon Compounds; C048844:anti-IgG; C052970:poly-N-isopropylacrylamide