Branched Polyethylenimine-Modified Upconversion Nanohybrid-Mediated Photoelectrochemical Immunoassay with Synergistic Effect of Dual-Purpose Copper Ions

Abstract

This work developed a near-infrared (near-IR) light-activated non-enzymatic signal-off photoelectrochemical (PEC) immunoassay for the ultrasensitive detection of α-fetoprotein (AFP) on the basis of branched polyethylenimine (BPEI)-modified upconversion nanoparticle (UCNP)@CdTe quantum dot (QD) nanostructures by coupling with the synergistic effect of dual-purpose copper ions. Emission light originated from NaYF4:Yb,Er UCNP was directly utilized through the electrostatic bonding of CdTe QDs to excite the separation of electron–hole pairs, resulting in the generation of obvious photocurrent under a 980 nm laser. By using polyclonal antibody-labeled cupric oxide nanoparticle as the secondary antibody, the nanolabel was introduced into the monoclonal anti-AFP antibody-modified microplates in the presence of target AFP. After treatment with acid, the as-released copper ion decreased the photocurrent through the synergistic effect with two issues: one was initially to form coordination with BPEI on the surface of UCNP, and then the near-IR excitation light and upconversion luminescence were attenuated due to the internal filter effect; another was to snatch the electrons flowing from the valence band of CdTe QD as the exciton trapping sites. Under optimal conditions, the dual-purpose Cu2+-activated signal-off PEC immunosensing platform exhibited a dynamic linear range from 10 pg mL–1 to 50 ng mL–1, accompanying the decreasing photocurrent with the increment of AFP concentration at an experimental detection limit of 1.2 pg mL–1. Importantly, good accuracy was achieved by this method in comparison with the results with human AFP ELISA kit for analysis of human serum samples. This dual-purpose Cu2+-activated PEC immunoassay brings a promising, enzyme-free and innovative thinking for the detection of low-abundance biomarkers.

An Electrochemical Sensor for the Detection of Cu2+ Based on Gold Nanoflowers‐modifed Electrode and DNAzyme Functionalized Au@MIL‐101 (Fe)

“…From the XRD pattern of the prepared MIL-101 (Fe) (Figure 2), we can see that the spectrum was basically consistent with the simulated spectrum and previous reports [20,15], which indicated the successful synthesis of MIL-101 (Fe). The high and sharp peaks meant that the material had a relatively high crystallinity.…”

“…To ensure the sensitivity of the electrochemical sensor, various functional nanomaterials are usually employed for signal amplification [13][14][15]. As one of the research hotspots in recent years, metal-organic frameworks (MOFs) have been used in many fields, such as catalysis [16], supercapacitors [17], adsorption and separation [18], and sensing [19][20][21].…”

Combined Mini-Parasep SF and Nanogold Immunoassay Show Potential in Stool Antigen Immunodetection for Giardiasis Diagnosis

“…For this reason, improving the detection level, sensitivity or reducing the test time will be an important goal in several fields, so nanotechnology is considered a target field for developing the diagnostic techniques being based on functionalization of nanoparticles from gold to carbon as antibody carriers 6 . Enzyme free immunoassays bring a promising and innovative thinking for the detection of low-abundance biomarkers through a near-infrared activated non-enzymatic signal off photoelectrochemical immunoassay for ultrasensitive detection of serum proteins by upconversion nanoparticle structures coupled with copper ions 8 .…”

Harnessing Photoluminescent Properties of Carbon Nitride Nanosheets in a Hierarchical Matrix

“…To date, among those techniques, photoluminescent (PL) chemosensors have been widely explored for a wide range of analytes in diverse fields ranging from biology to environmental sciences, due to its simple optical setup and high sensitivity . Owing to conjugated system of most PAHs, it is feasible to develop a PL chemosensor to detect PAHs via one or more delicate photophysical mechanisms, such as fluorescence resonance energy transfer and inner‐filter effect (IFE) . However, despite numerous efforts, development of photoactive materials which are highly efficient and stable, low cost, and environment‐friendly for large‐scale application is still of challenge …”