Electrochemiluminescence Double Quenching System Based on Novel Emitter GdPO₄:Eu with Low-Excited Positive Potential for Ultrasensitive Procalcitonin Detection

Abstract

Nowadays, the electrochemiluminescence (ECL) immunosensor with the unique superiority of tunable luminescence and ultrahigh sensitivity has become one of the most promising immunoassay techniques, especially for low-abundance biomarkers analysis. However, the use of signal probes with high excited potential and applied emitters which owned good intensity but biotoxicity limited its application. Herein, an ECL resonance energy transfer strategy was developed based on protein bioactivity protection utilizing europium-doped phosphoric acid gadolinium (GdPO4:Eu) as novel low-potential luminophor (donor) and Pd@Cu2O as the quenching probe (acceptor). Specifically, GdPO4:Eu was first prepared by using the hydrothermal synthesis method to apply in ECL, and when it coexisted with K2S2O8, cathode, a strong ECL signal would be generated at a low potential of −1.15 V (vs Ag/AgCl), where the immunocompetence of antigens and antibodies can be maintained well. Electrical pair Eu3+/Eu2+, as the coreactant promoter, produced by potential excitation could produce more SO4 •– to accelerate the oxidation process of GdPO4:Eu. Meanwhile, Cu2O coated onto Pd (Pd@Cu2O), as a dual-quencher, enhanced the quenching effect of Pd alone and controlled the ECL intensity of the “signal on” state within a reasonable range. As a result, the proposed biosensor for detection of trace procalcitonin, a biomarker of systemic inflammatory response syndrome, exhibited a far low detection limit, 0.402 fg/mL (S/N = 3). Importantly, this work not only utilized a promising ECL emitter for biosensing platform construction but also had momentous potential in biomarker detection of disease diagnosis and clinical analysis.

A frogspawn-like Ag@C core–shell structure for an ultrasensitive label-free electrochemical immunosensing of carcinoembryonic antigen in blood plasma

“…The regression equations of both anodic ( I pa ) and cathodic ( I pc ) peaks were I pa = 199.09 v 1/2 + 25.13 and I pc = −174.46 v 1/2 − 30.35, respectively, indicating that the redox reaction was controlled by diffusion. 35 Generally, the electro-active surface area of the modified electrode can be calculated according to the Randles–Sevcik equation I = 2.69 × 105 A × D 1/2 n 3/2 v 1/2 C , 36 where n is the number of electrons transferred in the redox reaction ( n = 1), A is the electrode electrochemical active area, D is the diffusion coefficient (6.70 × 10 −6 cm 2 s −1 , 25 °C), C is the concentration of the reactant (5 × 10 −3 mol L −1 Fe(CN) 6 3−/4− ), v is the scan rate (V s −1 ) and I is the peak current (μA) of the CV measurement. Here, the electro-active surface area of Ag@C NFSs/GCE was calculated to be 0.0827 cm 2 , 1.17 times higher than the initial surface area of the bare GCE ( d = 3 mm, 0.0707 cm 2 ), suggesting that Ag@C NFSs would greatly enlarge the surface area of the modified electrode, leading to remarkably accelerated electron transfer on the electrode surface.…”

Magnetic Bead-Based Electrochemical Immunoassays On-Drop and On-Chip for Procalcitonin Determination: Disposable Tools for Clinical Sepsis Diagnosis

“…Several methods have been reported for PCT determination, mainly based in the selective recognition provided by immunological interactions. These methodologies include immunoturbidimetric assays [9], chemiluminescent immunoassays [10][11][12][13][14][15][16], immunochromatographic assays [17][18][19][20][21][22], surface plasmon resonance biosensors [23][24][25], fluorescence immunosensors [26][27][28][29][30][31][32], ellipsometry immunosensors [33], colorimetric immunoassays [34][35][36], and electrochemical immunoassays [37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54][55][56]. Even differen...…”

Dual-Mode Sensing Platform Guided by Intramolecular Electrochemiluminescence of a Ruthenium Complex and Cationic N,N-Bis(2-(trimethylammonium iodide)propylene) Perylene-3,4,9,10-tetracarboxydiimide for Estradiol Assay

“…After the specific recognition of the aptamer chain and E2 was completed, the redundant aptamer will form a double helix structure with the complementary chain, which modified with PDA + to form a new quenching probe. As depicted in Scheme , the PDA + -bearing multifunctional DNA chain can help in the formation of a Ru complex (donor)–PDA + (acceptor) energy transfer pair, which initiated the changes in ECL signals to improve the analysis sensitivity . Additionally, PDA + , having excellent electrochemical properties of oxidation reducibility, can provide an obvious and clear electrochemical signal as the complement of EC detection information.…”