Cholesterol biosensing with a polydopamine-modified nanostructured platinum electrode prepared by oblique angle physical vacuum deposition

Abstract

This paper reports a novel cholesterol biosensor based on nanostructured platinum (Pt) thin films prepared by Magnetron Sputtering (MS) in an oblique angle (OAD) configuration. Pt thin films were deposited onto a gold screen-printed electrode and characterized using Rutherford Back Scattering (RBS), Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), Cyclic Voltammetry (CV), X-ray Photo-electron Spectroscopy (XPS), Atomic Force Microscopy (AFM) and wetting analysis. Our results confirmed that the film is highly porous and formed by tilted nanocolumns, with an inclination of around 40º and a total thickness of 280 nm. XRD and CV analysis confirmed the polycrystalline nature of the Pt thin film. Cholesterol oxidase (ChOx) was covalently immobilized using a bioinspired polymer, polydopamine (PDA), via Schiff base formation and Michael-type addition. After being immobilized, ChOx displayed an apparent activation energy of 34.09 kJ mol-1 and a Michaelis constant (K M) equal to 3.65 mM, confirming the high affinity between ChOx and cholesterol and the excellent ability of the PDA film for immobilizing biological material without degradation. Under optimized working conditions our biosensor presented a sensitivity of 14.3 mA M −1 cm −2 (R 2 :0.999) with a linear range up to 0.5 mM and a limit of detection of 10.5 µM (S/N = 3). Furthermore the biosensor exhibits a fast response (< 8 s), good anti-interference properties and high stability after relatively long-term storage (2 months).

Nickel/Copper Bilayer‐modified Screen Printed Electrode for Glucose Determination in Flow Injection Analysis

“…The roughness, expressed as Root Mean Square (RMS), presented values of 7.69 nm and 10.30 nm, as deduced from Figure S2a and S2b, respectively. These values agree with the RMS value reported in previous publications for similar configurations . Interestingly, the TOF‐SIM deep profile analysis (see Figure S3) showed that the nanocolumns presented a bilayer structure, with Ni atoms at the bottom of the nanocolumns and Cu atoms on the top, as expected from the preparation method described in the experimental section.…”

Kinetic energy-induced growth regimes of nanocolumnar Ti thin films deposited by evaporation and magnetron sputtering

“…in optics, biomedicine, sensors, microfluidics, LED fabrication, etc. [1][2][3][4][5][6][7][8]. These films have been classically deposited by the evaporation technique at glancing angles, which allowed the control of different microstructural features such as specific surface, density, pore distribution, pore connectivity, etc.…”

Mixed Self-Assembly of Polyethylene Glycol and Aptamer on Polydopamine Surface for Highly Sensitive and Low-Fouling Detection of Adenosine Triphosphate in Complex Media

“…Early detection of disease biomarkers is extremely important in clinical diagnosis, and much attention has been paid to the development of new technologies to determine early signs of various diseases, , such as enzyme-linked immunosorbent assay, fluorescense methods, , surface plasmon resonance, surface enhanced Raman spectroscopy, and so on. Among these, electrochemical technique has attracted much interest owing to its advantages such as high sensitivity, simple preparation, convenient operation, and low cost. − Currently, the sensitivity of electrochemical biosensors can be greatly improved by using signal amplification strategies, − but direct detection of targets in real complex media with electrochemical biosensors remains a challenge due to severe nonspecific adsorption.…”