Conducting polyamic acid membranes for sensing and site-directed immobilization of proteins.
A biosensor platform based on polyamic acid (PAA) is reported for oriented immobilization of biomolecules. PAA, a functionalized conducting polymer substrate that provides electrochemical detection and control of biospecific binding, was used to covalently attach biomolecules, resulting in a significant improvement in the detection sensitivity. The biosensor sensing elements comprise a layer of PAA antibody (or antigen) composite self-assembled onto gold (Au) electrode via N-hydroxysuccinimide (NHS) and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) linking. The modified PAA was characterized by Fourier transform infrared (FTIR), (1)H nuclear magnetic resonance (NMR), and electrochemical techniques. Cyclic voltammetry and impedance spectroscopy experiments conducted on electrodeposited PAA on Au electrode using ferricyanide produced a measurable decrease in the diffusion coefficient compared with the bare electrode, indicating some retardation of electron transfer within the bulk material of the PAA. Thereafter, the modified PAA surface was used to immobilize antibodies and then to detect inducible nitric oxide synthase and mouse immunoglobulin G (IgG) using enzyme-linked immunosorbent assay (ELISA), surface plasmon resonance (SPR), and amperometric techniques. ELISA results indicated a significant amplified signal by the modified PAA, whereas the SPR and amperometric biosensors produced significant responses as the concentration of the antigen was increased. Detection limits of 3.1×10(-3)ng/ml and 2.7×10(-1)ng/ml were obtained for SPR and amperometric biosensors, respectively.
Department of Chemistry and Center for Advanced Sensors and Environmental Monitoring, State University of New York at Binghamton, Binghamton, NY 13902, USA.
Naumih M
NM
Noah
Marcells
M
Omole
Samantha
S
Stern
Siyi
S
Zhang
Omowunmi A
OA
Sadik
Euodia H
EH
Hess
Jasmina
J
Martinovic
Priscilla G L
PG
Baker
Emmanuel I
EI
Iwuoha
D000818:Animals; D001555:Benzene Derivatives / Q000737:chemistry*; D015374:Biosensing Techniques / Q000379:methods*; D004058:Diffusion; D004553:Electric Conductivity; D055664:Electrochemical Techniques; D004566:Electrodes; D004797:Enzyme-Linked Immunosorbent Assay; D055767:Immobilized Proteins / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D008567:Membranes, Artificial; D051379:Mice; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism; D011108:Polymers / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D020349:Surface Plasmon Resonance; D013997:Time Factors
D001555:Benzene Derivatives; D055767:Immobilized Proteins; D008567:Membranes, Artificial; D011108:Polymers; C513053:polyamic acid; D052247:Nitric Oxide Synthase Type II