Self-enhanced Electrochemiluminescence Research Articles

Ultrasensitive electrochemiluminescent detection of cardiac troponin I based on a self-enhanced Ru(II) complex

To promote the luminous efficiency of luminophore, traditional electrochemiluminescence (ECL) immunoassay usually adopts the adding of coreactant into testing solution. However, many adverse micro-environmental factors in the solution are a limiting factor in ECL analytical techniques and received extensive attention. In our work, a self-enhanced ECL luminophore was synthesized by combining the coreactant (l-cysteine) and the luminophor (tris (4,4′-dicarboxylicacid-2,2′-bipyridyl) ruthenium(II) dichloride (Ru(dcbpy)32+)) to form one Ru(II) complex and was applied to fabricate a reagentless immunosensor for the detection of cardiac troponin I (cTnI) for the first time. Herein gold nanorods (AuNRs), due to their high specific surface area and good electrocatalytic ability, were used as carriers for the immobilization of Ru(II) complex and cTnI antibody to obtain the Ab2 bioconjugates as signal labels. The application of the self-enhanced Ru(II) complex not only avoided the addition of any coreactant into testing solution for simplifying the operation, but also achieved the intramolecular reaction for improving the ECL signal due to shorter electron transfer path and less energy loss. In view of these advantages, the proposed immunosensor achieved a wide linear range from 0.25pg/mL to 0.1ng/mL with an impressive detection limit of 0.083pg/mL for cTnI (S/N=3).

A super intramolecular self-enhanced electrochemiluminescence immunosensor based on polymer chains grafted on palladium nanocages.

An intramolecular self-enhanced electrochemiluminescent derivative is prepared by grafting polystyrene (PS)-based polymer chains with pendant Ru(ii) luminophore from poly(ethylenimine) (PEI) on the surface of palladium nanocages (PdNCs). In this way, the Ru(ii) luminophore and its co-reactive group (amine groups in PEI) exist in the same polymer molecule, which shortens the electronic transmission distance between them and enhances the luminous stability. Meanwhile, through atom transfer radical polymerization (ATRP), the loading amount of Ru(ii) luminophore is greatly increased. Therefore, the obtained electrochemiluminescent derivative (PdNC-PEI-PSRu) has high luminous efficiency and stability. Furthermore, due to their special nanostructures of porous walls and hollow interiors, PdNCs have great advantages in high specific surface areas and good electrocatalytic ability, which make them act as an excellent immobilized platform for PEI and detection antibody. Based on the sandwiched immunoreactions, a sensitive "signal on" electrochemiluminescence immunosensor is constructed for the detection of carbohydrate antigen 15-3 (CA 15-3). As a result, a wide linear range from 0.01 U mL(-1) to 120 U mL(-1) is acquired with a relatively low detection limit of 0.003 U mL(-1).

Ultrasensitive Apurinic/Apyrimidinic Endonuclease 1 Immunosensing Based on Self-Enhanced Electrochemiluminescence of a Ru(II) Complex

An alternative "signal on" immunosensor for ultrasensitive detection of apurinic/apyrimidinic endonuclease 1 (APE-1) was designed utilizing the self-enhanced electrochemiluminescence (ECL) of a novel Ru(II) complex functionalized coil-like nanocomposite as signal labels. The desirable self-enhanced ECL luminophore was achieved by combining the coreactant of poly(ethylenimine) (PEI) and the luminophor of bis(2,2'-bipyridine)-5-amino-1,10-phenanthroline ruthenium(II) [Ru(bpy)2(5-NH2-1,10-phen)(2+)] to form one novel Ru(II) complex, which exhibited significantly enhanced ECL efficiency and stability. Moreover, the carbon nanotubes (CNTs) were employed as nanocarriers for self-enhanced Ru(II) complex loading via π-π stacking to obtain the coil-like nanocomposite to act as signal probe. Compared with traditional ECL immunoassay, our proposed strategy is simple and sensitive, avoiding the adding of any coreactant into testing solution for signal amplification, and shows a detection limit down to subfemtogram per milliliter level under the optimized experimental condition.

Self‐Enhanced Electrochemiluminescence of an Iridium(III) Complex: Mechanistic Insight

Improved luminophore: The electrochemiluminescence (ECL) of an iridium complex self-enhanced up to 16 times is reported. Three excited states were observed in the emission spectra (see picture). The ECL efficiency of this complex is the highest reported for an iridium complex.