title: Electrochemical cortisol immunosensors based on sonochemically synthesized zinc oxide 1D nanorods and 2D nanoflakes.
abstract: We report on label free, highly sensitive and selective electrochemical immunosensors based on one-dimensional 1D ZnO nanorods (ZnO-NRs) and two-dimensional 2D ZnO nanoflakes (ZnO-NFs) which were synthesized on Au-coated substrates using simple one step sonochemical approach. Selective detection of cortisol using cyclic voltammetry (CV) is achieved by immobilizing anti-cortisol antibody (Anti-C(ab)) on the ZnO nanostructures (NSs). 1D ZnO-NRs and 2D ZnO-NFs provide unique sensing advantages over bulk materials. While 1D-NSs boast a high surface area to volume ratio, 2D-NSs with large area in polarized (0001) plane and high surface charge density could promote higher Anti-C(ab) loading and thus better sensing performance. Beside large surface area, ZnO-NSs also exhibit higher chemical stability, high catalytic activity, and biocompatibility. TEM studies showed that both ZnO-NSs are single crystalline oriented in (0001) plane. The measured sensing parameters are in the physiological range with a sensitivity of 11.86 µA/M exhibited by ZnO-NRs and 7.74 µA/M by ZnO-NFs with the lowest detection limit of 1 pM which is 100 times better than conventional enzyme-linked immunosorbant immunoassay (ELISA). ZnO-NSs based cortisol immunosensors were tested on human saliva samples and the performance were validated with conventional (ELISA) method which exhibits a remarkable correlation. The developed sensors can be integrated with microfluidic system and miniaturized potentiostat for point-of-care cortisol detection and such developed protocol can be used in personalized health monitoring/diagnostic.
authors: BioMEMS Microsystems Laboratory, Electrical and Computer Engineering, Florida International University, Miami, FL 33174, USA. Electronic address: pvabb001@fiu.edu.
authors: Phani Kiran
authors: PK
authors: Vabbina
authors: Center of Personalized Nanomedicine, Department of Immunology, Herbert Wertheim College of Medicine, Florida International University, Miami, FL 33199, USA.
authors: Ajeet
authors: A
authors: Kaushik
authors: BioMEMS Microsystems Laboratory, Electrical and Computer Engineering, Florida International University, Miami, FL 33174, USA.
authors: Nimesh
authors: N
authors: Pokhrel
authors: BioMEMS Microsystems Laboratory, Electrical and Computer Engineering, Florida International University, Miami, FL 33174, USA.
authors: Shekhar
authors: S
authors: Bhansali
authors: BioMEMS Microsystems Laboratory, Electrical and Computer Engineering, Florida International University, Miami, FL 33174, USA. Electronic address: npala@fiu.edu.
authors: Nezih
authors: N
authors: Pala
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D006046:Gold / Q000737:chemistry; D006801:Humans; D006854:Hydrocortisone / Q000737:chemistry / Q000302:isolation & purification*; D057230:Limit of Detection; D049329:Nanostructures; D043942:Nanotubes / Q000737:chemistry*; D015034:Zinc Oxide / Q000737:chemistry*
chemical_list: D006046:Gold; D015034:Zinc Oxide; D006854:Hydrocortisone
keywords: Cortisol sensing; Immunosensor; Sonochemistry; ZnO nanoflakes; ZnO nanorods