Abstract:
A novel kind of nanohybrids with a "necklace-like" morphology was prepared via one-step co-assembly of amphiphilic random copolymer and multi-walled carbon nanotubes (CNTs), which is successfully employed as the effective electrode material to construct an electrochemical sensor for highly sensitive detection of dopamine. A photo-crosslinkable amphiphilic copolymer poly(acrylic acid-
co-(7-(4-vinylbenzyloxy)-4-methyl coumarin)-
co-ethylhexyl acrylate) (PAVE) was synthesized firstly via one-step free radical polymerization. The chemical structure of the resultant PAVE copolymer was confirmed by Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance spectroscopy (
1H-NMR). Then PAVE copolymer was co-assembled with CNTs in aqueous solution, generating hybrid assembly of PAVE/CNTs. As characterized by transmission electron microscopy (TEM), the obtained PAVE/CNTs hybrids showed "necklace-like" morphology with PAVE nanoparticles as the beads and CNTs as the long axis. Thanks to the enhanced binding interactions between PAVE copolymers and CNTs sidewalls upon photo-crosslinking as well as the steric exclusion among PAVE/CNTs nanohybrids, the obtained nanohybrids showed good dispersion stability in aqueous solution and preserved the intrinsic structural properties of CNTs. For application as a sensor, PAVE/CNTs were used as the electrode material to modify the surface of glassy carbon electrode (GCE). A robust composite film with cross-conjugated network was formed on the electrode surface, resulting in an electrochemical sensor. Due to the large surface area of the resulting sensor film and the superior electrical conductivity of such long conducting nanohybrids, the as-prepared dopamine sensor showed a significantly wide linear detection range (4-90
μmol/L) and low detection limitation (0.24
μmol/L) for dopamine. The sensor also showed excellent anti-interference property, which is successfully applied to detect dopamine in real urine samples, demonstrating a promising feature for practical application in biomedical diagnosis. This rationally integrated hierarchical nano-micro architecture, which can be served as a versatile platform for immobilizing functional factors, gives rise to a series of advantages compared with the traditional cloddy polymer/CNTs nanocomposites, such as increased mechanical stability, higher specific surface area, larger loading capacity of functional factors, and better electrical conductivity, thereby showing great application potential in a wide range of fields, like biosensors and other microelectronic devices.