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A multiple signal-amplified electrochemiluminescence (ECL) urea sensor was designed based on a self-enhanced probe and SiO

An ultrasensitive electrochemiluminescence (ECL) biosensor was developed based on MIL-53(Al)@CdS QDs and SiO2@AuNPs for trichlorfon detection. Metal–organic frameworks (MOFs) were used as a loading platform that provided a large surface area to load targets and modified materials onto the electrode. At the same time, SiO2@AuNPs loaded plenty of AuNPs which effectively increased the ECL resonance energy transfer between the CdS QDs, so that the ECL signal was strongly quenched and resulted in an amplified response. In the range of 10−11–10−4 M, the ECL response showed a linear relationship with the concentration (logarithm) of trichlorfon, and the detection limit was 5.1 × 10−12 M (S/N = 3). When the biosensor was applied to detect trichlorfon in lettuce, broccoli, cucumber, and chives, the recoveries obtained from the spiked samples were 97%–105%, 102%–104%, 100%–104%, and 98%–104%, respectively. Thus, this novel ECL biosensor has potential applications for the analysis of trichlorfon in food samples.

A novel ratiometric electrochemiluminescence (ECL) system based on gold nanostars (AuNSs) support was constructed for the determination of hypotonicity-induced ATP release from HepG2 cells. AuNS@Lu nanoprobe was used as anodic luminophore and K

In photoelectrochemical sensor (PEC sensor), sensitivity and selectivity are two essential factors which are determined by photosensitive of materials and identification of elements. Herein, a novel PEC aptamer sensor for streptomycin-specific detection was developed, with which the visible-light-active TiO2/BiOI/BiOBr heterostructure and aptamers were employed as photoactive material and bio-identification elements, separately. The combination of an appropriate amount of TiO2 with BiOI/BiOBr enhanced the photocurrent response, and thus is beneficial to the construction of PEC sensors. In addition, the one-pot synthesis of TiO2/BiOI/BiOBr has the advantage of being environmentally-friendly. Under optimized conditions, the photocurrent response of aptamer/TiO2/BiOI/BiOBr/ITO is linear with SRT concentration from 0.05 to 150 nM, and the detection limit (S/N = 3) is as low as 0.04 nM. This novel PEC sensing strategy provided an ultra-sensitive sensor with high selectivity and stability for SRT detection.

An aptasensor based on MIL-53(Al)@CdTe was designed for multiple determination of Hg2+ and Pb2+ by electrochemiluminescence (ECL). Upon the recognition of Hg2+, aptamer 2-AuNPs form hairpin structures and are removed from the electrode. While in the presence of Pb2+, aptamer 1-PtNPs capture the target ions and form G-quadruplexes, and then bring PtNPs close enough to CdTe QDs to produce ECL resonance energy transfer. Upon aptamer interaction with Hg2+ and Pb2+, decreased ECL intensity was observed due to enhanced resonance energy transfer (ERET) and attenuated surface plasmon resonance (SPR). The ECL intensity difference (ΔECL) could therefore be used to detect heavy-metal ions with detection limits of 4.1 × 10−12 M (path 1, Hg2+), 3.7 × 10−11 M (path 2, Pb2+), and 2.4 × 10−11 M (path 3, Pb2+). The aptasensor could also be used for detecting Hg2+ and Pb2+ in fish and shrimp samples with good recoveries.

A sensitive electrochemiluminescence (ECL) aptasensor based on 3D graphene is described for thrombin detection utilizing nitrogen-doped graphene quantum dots doped silica (NGQDs@SiO2) nanocomposite labeling as an enhancer. Ru(bpy)32+-Pt nanoparticles (Ru-PtNPs) with an ECL signal were dropped onto a 3D graphene-modified electrode, and then, a complementary thrombin aptamer (cDNA) was conjugated to the Ru-PtNPs. Finally, NGQDs@SiO2, coupled with the thrombin aptamer as the booster, was attached to the electrode surface by using hybridization with the cDNA, and the ECL intensity was efficiently enhanced. The target thrombin induced the NGQDs@SiO2 nanocomposites labeled with the thrombin (TB) aptamer to be extracted because of their strong binding with thrombin. The immobilization amount of NGQDs@SiO2 on the modified electrode decreased. Thus, the presence of thrombin could result in a decrease in the ECL signal. On the basis of the signal amplification factors, the fabricated ECL aptasensor demonstrated excellent properties with concentrations varying from 2.0 pM to 50 nM and a detection limit of 23.1 fM.

A convenient photoelectrochemical sensor was constructed based on the synergistic contributions of an ultrathin BiOCl nanosheet and anchored TiO2 nanoparticles to detect the organophosphorus pesticide chlorpyrifos. As expected, the fabricated heterostructure showed a distinct improvement in photocurrent intensity compared with pristine BiOCl and TiO2. This remarkable enhancement may be attributed to the separation and transfer of photogenerated charge carries, which benefit from intimate interfacial interactions between the ultrathin BiOCl nanosheets and TiO2 nanoparticles. Based on the robust photocurrent signal, a novel PEC sensor was established for the sensitive and selective detection of chlorpyrifos. The as-fabricated PEC sensor demonstrates many advantages such as a wide linear range of 1–12 μM, a low detection limit of 0.11 μM, S/N = 3, and remarkable convenience, which provides a general format for chlorpyrifos detection in green vegetable analysis.

An ultrasensitive electrochemiluminescence (ECL) biosensor was developed based on MIL-53(Al)@CdS QDs and SiO

In photoelectrochemical sensor (PEC sensor), sensitivity and selectivity are two essential factors which are determined by photosensitive of materials and identification of elements. Herein, a novel PEC aptamer sensor for streptomycin-specific detection was developed, with which the visible-light-active TiO

Here, we developed an electrochemiluminescence (ECL) aptasensor for ultrasensitive detection of thrombin (TB) based on a synergistic effect of nanoparticles sensitization and cyclic catalysis of Cu2O. The aptasensor is constructed from three parts: firstly, three dimensional (3D) graphene was dropped onto the electrode to accelerate electron transfer. Then, the synthesized Cu2O-multiwalled carbon nanotubes (MWCNTs) were loaded onto the surface of 3D graphene. Finally, after TB aptamers linked to MWCNTs, Ru(bpy)32+- doped silica nanoparticles (RuSiNPs) were marked onto the surface. When detection of TB, the aptamers folded into G-quadruplex's that made the RuSiNPs get closer to the Cu2O. As a photocatalysis, Cu2O was excited by the ECL of RuSiNPs and generated holes and electrons which could catalyze the ECL reaction to emit much light, and the light could excite Cu2O again. Hence, a cyclic catalytic aptasensor was built. Under the optimal conditions, this aptasensor for TB detection showed good sensitivity with wide linearity (5 × 10−15 M - 5 × 10−11 M) and low detection limit (1.3 × 10−15 M).

In this work, the feasibility of a novel sensitive electrochemiluminescence aptasensor for the detection of lysozyme using Ru(bpy)32+-Silica@Poly-L-lysine-Au (RuSiNPs@PLL-Au) nanocomposites labeling as an indicator was demonstrated. The substrate electrode of the aptasensor was prepared by depositing gold nanoparticles (AuNPs) on 3D graphene-modified electrode. The lysozyme binding aptamer (LBA) was attached to the 3D graphene/AuNPs electrode through gold-thiol affinity, hybridized with a complementary single-strand DNA (CDNA) of the lysozyme aptamer labeled by RuSiNPs@PLL-Au as an electrochemiluminescence intensity amplifier. Thanks to the synergistic amplification of the 3D graphene, the AuNPs and RuSiNPs@PLL-Au NPs linked to Ru(bpy)32+-ECL further enhanced the ECL intensity of the aptasensor. In presence of lysozyme, the CDNA segment of the self-assembled duplex was displaced by the lysozyme, resulting in decreased electrochemiluminescence signal. Under the optimized conditions, the decrease in electrochemiluminescence intensity varied proportionally with the logarithmic concentration of the lysozyme from 2.25 × 10-12 to 5.0 × 10-8 mol L-1, and the detection limit was estimated to 7.5 × 10-13 mol L-1. The aptasensor was further tested in real samples and found reliable for the detection of lysozyme, thus holding great potential application in food safety researches and bioassay analysis.

An aptasensor based on MIL-53(Al)@CdTe was designed for multiple determination of Hg

A dual gears electrochemiluminecence (ECL) aptasensing strategy for multiple selective determination of kanamycin and neocycin was designed on the basis of the combination of kanamycin and neocycin induced dual gears conversion, the loading platform of metal-organic frameworks (MOFs), surface plasmon resonance (SPR) and ECL resonance energy transfer (ERET) between CdS QDs and AuNPs (or PtNPs). In the absence of target, the dual gears were "off". Then the B1-AuNP (gear B) and aptamer 1-PtNPs acted as signal quenching elements to quench ECL intensity due to ERET process. Upon addition of kanamycin, the aptamer 1-PtNPs were removed from the gear gradually, the ECL was enhanced due to SPR process between AuNPs and CdS QDs. After the incubation of aptamer 2, the dual gears were "off" again and ECL intensity was decreased by ERET process between AuNPs and CdS QDs. In the presence of neomycin, dual gears were "on" again, the ECL signal was enhanced by SPR process between AuNPs and CdS QDs. Under optimal condition, the proposed aptasensor exhibited wide linear ranges of kanamycin (10−10–10−6 M) and neomycin (10−9–10−5 M), and relatively low detection limits to kanamycin (1.7 × 10–11 M) and neomycin (3.5 × 10−10 M). The developed aptasensor realized the multiple ECL detection of kanamycin and neomycin with single luminophore, and was successfully applied to the detection of kanamycin and neomycin in food samples.