title: Paper-Based Analytical Biosensor Chip Designed from Graphene-Nanoplatelet-Amphiphilic-diblock-co-Polymer Composite for Cortisol Detection in Human Saliva.
abstract: Cortisol has been identified as a biomarker in saliva to monitor psychological stress. In this work, we report a label-free paper-based electrical biosensor chip to quantify salivary cortisol at a point-of-care (POC) level. A high specificity of the sensor chip to detect cortisol with a detection limit of 3 pg/mL was achieved by conjugating anticortisol antibody (anti-CAB) on top of gold (Au) microelectrodes using 3,3'-dithiodipropionic acid di(N-hydroxysuccinimide ester (DTSP) as a self-assembled monolayer (SAM) agent. The electrode design utilized poly(styrene)-block-poly(acrylic acid) (PS67-b-PAA27) polymer and graphene nanoplatelets (GP) suspension coated on filter paper to increase the sensitivity of the immune response. A biosensor chip was then integrated with a lab-built low-cost miniaturized printed circuit board (PCB) to provide an electrical connection and to wirelessly transmit/receive electrical signals using MATLAB. This fully integrated proposed hand-held device successfully exhibited a wide cortisol-detection range from 3 pg/mL to 10 μg/mL, with a sensitivity of 50 Ω (pg mL-1)-1. The performance of the proposed cortisol sensor chip was validated using an enzyme-linked immunosorbent assay (ELISA) technique with a regression value of 0.9951. The advantages of the newly developed cortisol immune biosensor over previously reported chips include an improved limit of detection, no need for additional redox medium for electron exchange, faster response to achieve stable data, excellent shelf life, and its economical production.
authors.affiliation: Biomedical Research Center, Carle Foundation Hospital , Urbana, Illinois United States.
authors.forename: Muhammad S
authors.initials: MS
authors.lastname: Khan
authors.affiliation: Biomedical Research Center, Carle Foundation Hospital , Urbana, Illinois United States.
authors.forename: Santosh K
authors.initials: SK
authors.lastname: Misra
authors.affiliation: Biomedical Research Center, Carle Foundation Hospital , Urbana, Illinois United States.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Biomedical Research Center, Carle Foundation Hospital , Urbana, Illinois United States.
authors.forename: Enrique
authors.initials: E
authors.lastname: Daza
authors.affiliation: Biomedical Research Center, Carle Foundation Hospital , Urbana, Illinois United States.
authors.forename: Aaron S
authors.initials: AS
authors.lastname: Schwartz-Duval
authors.affiliation: Biomedical Research Center, Carle Foundation Hospital , Urbana, Illinois United States.
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Kus
authors.affiliation: Saltlake Mind Set, Kolkata, India.
authors.forename: Debanjan
authors.initials: D
authors.lastname: Pan
authors.affiliation: Biomedical Research Center, Carle Foundation Hospital , Urbana, Illinois United States.
authors.forename: Dipanjan
authors.identifier: 0000-0003-0175-4704
authors.initials: D
authors.lastname: Pan
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry*; D015415:Biomarkers / Q000032:analysis; D015374:Biosensing Techniques / Q000191:economics / Q000295:instrumentation*; D002623:Chemistry Techniques, Analytical / Q000191:economics / Q000295:instrumentation*; D004797:Enzyme-Linked Immunosorbent Assay; D006046:Gold / Q000737:chemistry; D006108:Graphite / Q000737:chemistry*; D064368:Healthy Volunteers; D006801:Humans; D006854:Hydrocortisone / Q000032:analysis*; D057230:Limit of Detection; D008839:Microelectrodes; D010209:Paper; D011137:Polystyrenes / Q000737:chemistry*; D015203:Reproducibility of Results; D012463:Saliva / Q000737:chemistry*; D013315:Stress, Psychological / Q000175:diagnosis; D013388:Succinimides / Q000737:chemistry
chemical_list: D000180:Acrylic Resins; D015415:Biomarkers; D011137:Polystyrenes; D013388:Succinimides; C006903:carbopol 940; D006046:Gold; D006108:Graphite; C011240:dithiobis(succinimidylpropionate); D006854:Hydrocortisone