title: Microneedle array-based carbon paste amperometric sensors and biosensors.
abstract: The design and characterization of a microneedle array-based carbon paste electrode towards minimally invasive electrochemical sensing are described. Arrays consisting of 3 × 3 pyramidal microneedle structures, each with an opening of 425 µm, were loaded with a metallized carbon paste transducer. The renewable nature of carbon paste electrodes enables the convenient packing of hollow non-planar microneedles with pastes that contain assorted catalysts and biocatalysts. Smoothing the surface results in good microelectrode-to-microelectrode uniformity. Optical and scanning electron micrographs shed useful insights into the surface morphology at the microneedle apertures. The attractive performance of the novel microneedle electrode arrays is illustrated in vitro for the low-potential detection of hydrogen peroxide at rhodium-dispersed carbon paste microneedles and for lactate biosensing by the inclusion of lactate oxidase in the metallized carbon paste matrix. Highly repeatable sensing is observed following consecutive cycles of packing/unpacking the carbon paste. The operational stability of the array is demonstrated as well as the interference-free detection of lactate in the presence of physiologically relevant levels of ascorbic acid, uric acid, and acetaminophen. Upon addressing the biofouling effects associated with on-body sensing, the microneedle carbon paste platform would be attractive for the subcutaneous electrochemical monitoring of a number of physiologically relevant analytes.
authors.affiliation: Department of NanoEngineering, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0448, USA.
authors.forename: Joshua Ray
authors.initials: JR
authors.lastname: Windmiller
authors.forename: Nandi
authors.initials: N
authors.lastname: Zhou
authors.forename: Min-Chieh
authors.initials: MC
authors.lastname: Chuang
authors.forename: Gabriela
authors.initials: G
authors.lastname: Valdés-Ramírez
authors.forename: Padmanabhan
authors.initials: P
authors.lastname: Santhosh
authors.forename: Philip R
authors.initials: PR
authors.lastname: Miller
authors.forename: Roger
authors.initials: R
authors.lastname: Narayan
authors.forename: Joseph
authors.initials: J
authors.lastname: Wang
mesh_terms: D000082:Acetaminophen / Q000032:analysis; D001205:Ascorbic Acid / Q000032:analysis; D057219:Biofouling; D015374:Biosensing Techniques / Q000295:instrumentation* / Q000379:methods*; D002244:Carbon / Q000737:chemistry*; D002384:Catalysis; D055664:Electrochemical Techniques / Q000379:methods*; D005947:Glucose / Q000032:analysis; D006861:Hydrogen Peroxide / Q000032:analysis; D019344:Lactic Acid / Q000032:analysis; D008839:Microelectrodes; D014159:Transducers; D014527:Uric Acid / Q000032:analysis
chemical_list: D014527:Uric Acid; D019344:Lactic Acid; D000082:Acetaminophen; D002244:Carbon; D006861:Hydrogen Peroxide; D005947:Glucose; D001205:Ascorbic Acid