In situ growth of L012-reduced gold nanoparticles-loaded graphitic carbon nitride nanocomposite for potential-resolved ratiometric electrochemiluminescence analysis

Abstract

Background

Most electrochemiluminescence (ECL) analytical methods involve only changes in one single signal, which greatly limits their high sensitivity and stability for applied research. Potential-resolved electrochemiluminescence (PRECL), which provides calibrated analysis by self-correcting signal responses from dual channels, has attracted great interest in recent years. However, research on PRECL nanomaterials is still at an early stage. It is critical to develop a novel PRECL nanocomposite with high intensity in light emission, high resolution in potential separation, and reduced complexity in reaction systems for accurate detection.

Results

Here, a novel PRECL nanocomposite, L012-Au/g-C₃N₄, was synthesized by in situ growth of L012-reduced gold nanoparticles (L012-Au) on the surface of graphitic carbon nitride (g-C₃N₄) nanosheets. The g-C₃N₄ nanosheets served as effective carriers for L012 molecules and L012-Au, as well as efficient cathodic ECL emitters. With the addition of a single co-reactant (K₂S₂O₈), two fully separated ECL peaks were observed around −1.3 V (ECL-1) and +0.6 V (ECL-2) at neutral conditions. The catalytic character of the incorporated gold nanoparticles accelerated the anodic ECL reaction and greatly enhanced the ECL intensity. Furthermore, an ECL mechanism based on the competitive relationship between K₂S₂O₈ and dissolved oxygen was proposed. When dopamine (DA) was introduced into the PRECL reaction system, ECL-1 remained essentially unchanged, while ECL-2 intensity was significantly reduced. By analyzing the intensity ratio of ECL-2 to ECL-1 (I₂/I₁) to the detecting target, a ratiometric DA sensor with high sensitivity and stability was successfully constructed.

Significance

A nanocomposite L012-Au/g-C₃N₄ that can induce high-intensity ECL with two separated potentials in each polarity has been prepared by a simple synthetic method. The developed ratiometric sensor can eliminate systematic errors and improve accuracy. In addition, the multifunctionality of the nanocomposite and the necessity of only one co-reactant for neutral-condition ECL greatly reduced the reaction complexity. Our work offers new PRECL solutions to design highly sensitive and stable multi-response detection systems for in vitro diagnostics.