Highly Sensitive and Selective Field‐Effect‐Transistor NonEnzyme Dopamine Sensors Based on Pt/Conducting Polymer Hybrid Nanoparticles

Abstract

Dopamine (DA), as one of catecholamine family of neurotransmitters, is crucially important in humans owing to various critical effects on biometric system such as brine circuitry, neuronal plasticity, organization of stress responses, and control of cardiovascular and renal organizations. Abnormal level of dopamine in the central nervous system causes several neurological diseases, e.g., schizophrenia, Parkinson's disease, and attention deficit hybperactivity disorder (ADHD)/attention deficit disorder (ADD). In this report, we suggest the fabrication of nonenzyme field effect transistor (FET) sensor composed of immobilized Pt particle decorated conducting-polymer (3-carboxylate polypyrrole) nanoparticles (Pt_CPPy) to detect dopamine. The hybrid nanoparticles (NPs) are produced by means of facile chemical reduction of pristine CPPyNP-contained Pt precursor (PtCl4 ) solution. The Pt_CPPys are then immobilized on an amine-functionalized (-NH2 ) interdigitated-array electrode substrate, through the formation of covalent bonds with amine groups (-CONH). The resulting Pt_CPPy-based FET sensors exhibit high sensitivity and selectivity toward DA at unprecedentedly low concentrations (100 × 10(-15) m) and among interfering biomolecules, respectively. Additionally, due to the covalent bonding involved in the immobilization process, a longer lifetime is expected for the FET sensor.

Bioresorbable Silicon Nanomembranes and Iron Catalyst Nanoparticles for Flexible, Transient Electrochemical Dopamine Monitors

“…Here, the hybrid type NPs provide a key role in inducing a chemical reaction to evaluate dopamine levels as described in Figure c. A fundamental mechanism responsible for dopamine detection is that dopamine molecules are adsorbed onto the CPPy surface of the hybrid NPs (Fe 3+ _CPPy NPs) via pi–pi interactions through six‐membered benzene rings (dopamine molecules) fused to five‐membered nitrogen‐containing rings (CPPy) . Such accumulated DA is efficiently oxidized to form DA‐derived quinone, i.e., dopamine‐ o ‐quinone (DQ), catalyzed by a number of Fe‐based NPs .…”

“…Figure a presents an illustrative diagram to form a new, biocompatible catalytic product of Fe 2+ _ or Fe 3+ _CPPy NPs by chemical synthesis. Carboxylated polypyrrole nanoparticles (CPPy NPs) were obtained from a blend of pyrrole, pyrrole‐3‐carboxylic acid as a carboxyl group (COOH) supplier, iron (III) chloride (FeCl 3 ), and polyvinyl alcohol (PVA) in purified water, followed by dispersion of FeCl 2 or FeCl 3 as a catalytic precursor of an iron (Fe 2+ or Fe 3+ ) in the presynthesized CPPy NPs . The subsequent addition of sodium borohydride (NaBH 4 , 10 mg) formed Fe 2+ or Fe 3+ ions to Fe 3 O 4 , Fe 2 O 3 nanoparticles, respectively, after ultrasonication for 2 h, and the resulting nanoparticles were evenly distributed on the surface of the CPPy NPs.…”

“…The subsequent addition of sodium borohydride (NaBH 4 , 10 mg) formed Fe 2+ or Fe 3+ ions to Fe 3 O 4 , Fe 2 O 3 nanoparticles, respectively, after ultrasonication for 2 h, and the resulting nanoparticles were evenly distributed on the surface of the CPPy NPs. To evaluate fundamental properties of the synthesized materials, we performed a wide range of comparative examinations and analyses on a well‐known, popular platinum (Pt)‐based nanoparticles formed with similar approaches to Fe‐based catalysts . A series of transmission electron microscopy (TEM) images shown in Figure b present sizes and surface properties of respective nanoparticles, CPPy NPs (left), Pt_CPPy NPs (middle), and Fe 3+ _CPPy NPs (right), indicating uniform dispersion of catalyst nanoparticles with dimensions of several to tens of nanometers tied to CPPy NPs of ≈100 nm in size.…”

“…Figure b exhibited measured fractional changes in conductance of a typical device as a function of time while exposure to a solution with various DA concentrations. Here, adsorbed DA molecules on the surface of Fe 2 O 3 NPs catalysts were oxidized to DQ molecules, and generated electrons were transferred to p‐doped Si NM electrodes through conductive CPPy NPs . As a result, the number of holes in p‐doped Si NMs decreased, and such reduced carriers caused sensitive variations in electrical characteristics in response to even a picomolar concentration of dopamine.…”

“…Presumably, such selective capability could be attributed to the pi–pi stacking interactions between the polypyrrole and DA, however, the benzene rings are absent in AA and UA molecules so that they do not interact with the conductive polymer‐based sensor system. Even though the benzene rings are present in molecular structures of EP and NE, it is difficult to form pi–pi interactions due to a steric hindrance from an additional functional group . Microscopic images of the Fe_CPPy NPs after DA detection appears in Figure S8 (Supporting Information).…”