Dual-emitting BP-CdTe QDs coupled with dual-function moderator TiO2 NSs for electrochemiluminescence ratio bioassay

Dual emitting aggregation-induced electrochemiluminescence from tetrastyrene derivative for chloramphenicol detection

Chloramphenicol (CAP) poses a threat to human health due to its toxicity and bioaccumulation, and it is very important to measure it accurately and sensitively. This work explored a host-guest recognition strategy to mediate dual aggregation-induced electrochemiluminescence (AIECL) of 1,1,2,2-tetrakis(4-(pyridin-4-yl) phenyl)-ethene (TPPE) for ratio detection of CAP, in which, cucurbit[8]uril (CB[8]) served as host to assemble guest TPPE. The resulting supramolecular complex CB[8]-TPPE exhibited excellent dual-AIECL-emission with signal strength approximately four times that of TPPE aggregates and black hole quencher-1 (BHQ1) could efficiently quench dual-AIECL signal. CB[8]-TPPE coupled dual-function quencher BHQ1 and high-efficiency DNA reactor to achieve ultra-sensitive detection of CAP, exhibiting a linearity range of 10 fmol·L-1-100 nmol·L-1 and limit of detection of 1.81 fmol·L-1. CB[8]-TPPE provides a novel way to improve the dual-emission of TPE derivatives and sets up a promising platform for CAP detection, demonstrating a good practical application potential.

An electrochemiluminescence aptasensor based on Ti3C2 QDs-1T/2H MoS2 nano-hybrid material for the highly sensitive detection of lincomycin

Developing a highly selective and sensitive analysis strategy for lincomycin (LIN) is of great significance for environmental protection and food safety. Herein, we reported a novel electrochemiluminescence (ECL) aptasensor based on Ti3C2 QDs-1T/2H MoS2 nano-hybrid luminophore for detection of LIN. The hybridization of Ti3C2 QDs and 1T/2H MoS2 endowed nanocomposite with structural and compositional advantages for boosting the ECL performance of QDs by about three times. This enhancement could be attributed to the remarkable electrocatalytic activity and high conductivity exhibited by 1T/2H MoS2. Secondly, the great surface area of 1T/2H MoS2 is conducive to the high dispersion of Ti3C2 QDs, and its good conductivity could promote charge transfer. On the other hand, the excellent catalytic performance of 1T/2H MoS2 could facilitate the reduction of S2O82- to produce more radical, which significantly enhance the ECL signal of Ti3C2 QDs. Given these features, a sensor for detection of LIN was established based on specific recognition between target and aptamer. The sensor showed a good linear relationship (0.05 ng mL-1 ∼100 μg mL-1) with a detection limit as low as 0.02 ng mL-1. It is worth noting that this work has been validated in testing milk samples, exhibiting great potential application prospects in food analysis.

Nanotechnology in the diagnostic and therapy for Alzheimer's disease

Alzheimer's disease (AD) is a neurodegenerative disorder primarily characterized by β-amyloid plaque, intraneuronal tangles, significant neuronal loss and cognitive deficit. Treatment in the early stages of the disease is crucial for preventing or perhaps reversing the neurodegeneration in the AD cases. However, none of the current diagnostic procedures are capable of early diagnosis of AD. Further, the available treatments merely provide symptomatic alleviation in AD and do not address the underlying illness. Therefore, there is no permanent cure for AD currently. Better therapeutic outcomes need the optimum drug concentration in the central nervous system (CNS) by traversing blood-brain-barrier (BBB). Nanotechnology offers enormous promise to transform the treatment and diagnostics of neurodegenerative diseases. Nanotechnology based diagnostic tools, drug delivery systems and theragnostic are capable of highly sensitive molecular detection, effective drug targeting and their combination. Significant work has been done in this area over the last decade and prospective results have been obtained in AD therapy. This review explores the various applications of nanotechnology in addressing the varied facets of AD, ranging from early detection to therapeutic interventions. This review also looks at how nanotechnology can help with the development of disease-modifying medicines, such as the delivery of anti-amyloid, anti-tau, cholinesterase inhibitors, antioxidants and hormonal drugs. In conclusion, this paper discusses the role of nanotechnology in the early detection of AD, effective drug targeting to the CNS and theragnostic applications in the management of AD.

Facile synthesis of dual-ligand europium-metal organic gels for ratiometric electrochemiluminescence detecting I27L gene

Metal organic gels (MOGs) are a new kind of intelligent soft materials with excellent luminescence properties. However, MOGs with dual electrochemiluminescence (ECL) properties have not been reported. In this study, using Eu3+ as metal node, 4'-(4-carboxyphenyl)-2,2':6',2″-terpyridine (Hcptpy) and Luminol as organic ligands, a novel dual-ligand Europium-organic gels (Eu-L-H MOGs) were prepared by simple mixing at room temperature. On the one hand, Eu-L-H MOGs could exhibit strong and stable anodic ECL signals in the phosphate buffered saline (PBS) without the addition of co-reactants, which came from the blue emission of Luminol. On the other hand, using K2S2O8 as a cathodic co-reactant, Eu-L-H MOGs produced cathodic signals, which were derived from the red emission of Eu sensitized by Hcptpy through the antenna effect. Based on the independent dual ECL signals of Eu-L-H MOGs, we selected Alexa Flour 430 as the receptor and anodic ECL emission of Eu-L-H MOGs as the donor to construct the ECL resonance energy transfer (ECL-RET) ratio biosensor, which utilized exonuclease III assisted DNA cycle amplification to achieve ultrasensitive detection of the I27L gene. The detection linearity of I27L ranged from 1 fM to 10 nM, with a detection limit as low as 284 aM. This study developed a straightforward technique for obtaining a single luminescent material with dual signals, and further broadened the analytical application of MOGs in the realm of ECL.

Porous Complex-Mediated Dual Emission of Porphyrins for the Electrochemiluminescence Bioassay

Although porphyrins make up a promising class of electrochemiluminescence (ECL) luminophors, their aggregation-caused quenching (ACQ) characteristics lead to inferior ECL efficiency (ΦECL). Furthermore, current application of porphyrins is limited to cathodic emission. This work creatively exploited a cage-like porous complex (referred to as SWU-1) as the microreactor to recede the ACQ effect while modulating dual ECL emission of meso-tetra(4-carboxyphenyl)porphine (TCPP), which self-assembled with SWU-1 to form TCPP@SWU-1 nanocapsules (TCPP@SWU-1 NCs). As the microreactor, SWU-1 not only effectively constrained TCPP aggregation to improve electron-hole recombination efficiency but also improved stability of anion and cation radicals, thus significantly enhancing the dual emission of TCPP. Compared with TCPP aggregates, the resulting TCPP@SWU-1 NCs exhibited significantly enhanced anodic and cathodic emission, and their ΦECL was increased by 8.7-fold and 3.9-fold, respectively. Furthermore, black hole quencher-2 (BHQ2) can simultaneously quench anodic and cathodic signals. TCPP@SWU-1 NCs coupling BHQ2 conveniently achieved an ECL ratio detection of miRNA-126, and the limit of detection (S/N = 3) was 4.1 aM. This work pioneered the development of the cage-like porous complex SWU-1 as the microreactor to alleviate defects of the ACQ effect and mediate dual emission of TCPP. The coupling of dual-emitting TCPP@SWU-1 NCs and dual-function moderator BHQ2 created a novel single-luminophor-based ratio system for bioanalysis and provided a promising ECL analysis approach for miRNA-126.

Electrochemiluminescence immunoassay strategies based on a hexagonal Ru-MOF and MoS2@GO nanosheets: detection of 5-fluorouracil in serum samples

Herein, a competitive-type electrochemiluminescence immunosensor for ultrasensitive detection of 5-fluorouracil (5-FU) was fabricated. Ruthenium(II)-metal-organic framework (Ru-MOF) nanosheets were selected to act a promising ECL luminophore using tris(4,4'-dicarboxylic acid-2,2'-bipyridyl) ruthenium(II) dichloride (Ru(dcbpy)₃²⁺) as the organic ligand. The two-dimensional (2D) Ru-MOF nanosheets achieved an increased loading of Ru(dcbpy)₃²⁺ and effectively prevented leakage of the ECL emitter during application, which exhibited satisfactory ECL performance. Thin two-dimensional MoS₂@GO was used to modify the electrode as the sensing platform for improving the electron transfer rate and loading more 5-FU coating antigens due to its large specific surface area and piezoelectric catalytic efficiency. Under the optimized conditions, the proposed immunosensor presented high sensitivity, a wide detection range (0.0001 ng-100 ng mL^-1), a low limit of detection (0.031 pg mL^-1, S/N = 3), good specificity and stability. Furthermore, the immunosensor was successfully applied for the detection of 5-FU in human serum samples with satisfactory results, proving this strategy has potential applications in bioanalysis and clinical diagnosis.

Dual-emitting Iridium nanorods combining dual-regulating coreaction accelerator Ag nanoparticles for electrochemiluminescence ratio determination of amyloid-β oligomers

Iridium(III) complexes have been developed as eminent electrochemiluminescence (ECL) luminophores, but their current applications are only limited to anodic ECL emission because of weak cathodic ECL emission. This work explored poly(styrene-co-maleicanhydride) (PSMA) as functional reagent to modulate iridium(III) complexes to simultaneously emit bipolar ECL signals. The prepared iridium(III) nanorods (Ir NRs) were detected strong bipolar ECL emissions at +0.9 V and -2.0 V with N,N-diisopropylethylenediamine (DPEA) and persulfate (S₂O₈^2-) as coreactant, respectively. Meanwhile, Ag nanoparticles (Ag NPs) were developed as dual-regulating coreaction accelerator to boost the bipolar emissions of Ir NRs simultaneously. The dual-emitting Ir NRs coupled with dual-regulating coreaction accelerator Ag NPs facilitated the construction of mono-luminophore-based ECL ratio strategy for detecting amyloid-β oligomers (AβO). When the target AβO appeared, the Mg²⁺-dependent DNAzyme-powered biped walkers were unlocked to cleave single-stranded S1 immobilized on the surface of magnetic beads (MBs), resulting in the production of massive single-stranded ST. Then, the output ST cleaved hairpin H1 captured by Ir NRs modified electrode to produce numerous single strands, which could initiate the hybridization chain reaction (HCR) between Ag NPs-labeled H2 and Ag NPs-labeled H3 to introduce abundant Ag NPs onto the electrode surface. Due to the enhancement effect of Ag NPs on the bipolar ECL emissions from Ir NRs, the ECL ratio detection of AβO was achieved with the detection limit of 0.62 pM. The unique dual-emitting properties of Ir NRs coupled with dual-regulating effect of Ag NPs provided an interesting mono-luminophore-based ECL ratio sensing platform for biological analysis.