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Gold nanoparticles (Au NPs) based plasmonic probe was developed for sensitive and selective detection of Cu 2+ ion. The Au NPs were self-assembled on transparent indium tin oxide (ITO) film coated glass substrate using poly dimethyl diallyl ammonium chloride (PDDA) as a linker and then calcined at 400 °C to obtain pure Au NPs on ITO surface (ITO/Au NPs). The probe was fabricated by functionalizing l -cysteine (Cys) on to gold surface (ITO/Au NPs/Cys). The strong chelation of Cu 2+ with Cys formed a stable Cys-Cu complex, and resulted in the red-shift of localized surface plasmon resonance (LSPR) peak of the Au NPs. The introduction of bovine serum albumin (BSA) as the second complexant could form complex of Cys-Cu-BAS and further markedly enhanced the red-shift of the LSPR peak. This plasmonic probe provided a highly sensitive and selective detection towards Cu 2+ ions, with a wide linear detection range (10 −11 –10 −5 M) over 6 orders of magnitude. The simple and cost-effective probe was successfully applied to the determination of Cu 2+ in real samples. [ABSTRACT FROM AUTHOR]

Although the use of omethoate (OMT) for pests control is enormously economically beneficial for agricultural production, the high toxicity of OMT to nontarget organisms has resulted in the contamination of soil, river water, and food materials. Developing sensitive and convenient techniques to detect OMT residues is vital to society. Electrochemiluminescence (ECL) is a powerful analytical tool and has been widely applied in biosensors. To boost the co-reaction efficiency and ECL intensity, we introduced defective ZIF-8 as the novel cathodic luminophore. At the same time, defect generated by the doping of MoTe 2 nanoparticles into ZIF-8 could easily electrocatalytic reduce the co-reactor S 2 O 8 2− to SO 4 •- . Hence, based on the catalysis of defective ZIF-8, the ECL intensity of MoTe 2 /ZIF-8 nanocomposites is much higher than both ZIF-8 and MoTe 2 nanoparticles. By integration of as-prepared materials with specificity omethoate aptamer, the ECL sensor showed a broad linear range (10−10 g L−1 and 10−5 g L−1) and a comparatively low detection limit (3.3 × 10−11 g L−1). Besides, the ECL aptasensor appeared a good practical performance to detect potato and spinach extraction samples, which proposed a promising guideline for developing ECL aptasensors with high efficiency. •Defective ZIF-8 was induced by nanoparticle-doping via 'de novo' strategy. • The as-prepared defective ZIF-8 was employed as novel cathodic ECL luminophore. • High electrocatalytic active ZIF-8 significantly boosted co-reaction efficiency. • A high-performance ECL omethoate aptasensor was successfully established. • The ECL aptasensor exhibited good selectivity and sensitivity. [ABSTRACT FROM AUTHOR]

Developing a simple, rapid detection method for the analysis of edifenphos (EDI) is crucial due to its residue is harmful to acetylcholinesterase on the human cellular system, and cause a lot of complications. Herein, we synthesized visible light-responsive MoS 2 nanosheets decorated with Zinc phthalocyanine (ZnPc) nanoparticles (ZnPc/n-MoS 2). Due to the sensitization of ZnPc nanoparticles, the resulting ZnPc/n-MoS 2 exhibited narrower energy bandgap and efficient charge transfer. Especially, the carrier lifetime of ZnPc/n-MoS 2 is 2 more times longer than n-MoS 2 , and the photocurrent intensity of ZnPc/n-MoS 2 is 24 times of n-MoS 2 and 22 times of ZnPc nanoparticles under visible light irradiation. Further, a visible light-responsive ultrasensitive photoelectrochemical (PEC) aptasensor for selectivity recognition of EDI was triumphantly established by using EDI aptamer as a biorecognition element, which exhibited a wide linear ranking from 5 ng L–1 to 10 μg L–1 (R2 = 0.996) and a low detection limit of 1.667 ng L–1 (S/N = 3). The splendid performance of the ZnPc/n-MoS 2 nanosheet ultrasensitive sensing platform can be applied to detect the concentration of EDI in food, biomedical and environmental analysis. • Visible light-responsive ZnPc/n-MoS 2 was fabricated used ZnPc nanoparticles as sensitizer. • The carrier lifetime and photocurrent intensity of ZnPc/n-MoS 2 is 2 more and 24 times of n-MoS 2 , respectively. • A visible light-driven PEC edifenphos aptasensor was firstly successfully established. • The proposed aptasensor exhibited good selectivity and sensitivity for edifenphos detection. [ABSTRACT FROM AUTHOR]

Abstract Rational design and fabrication of Z-scheme visible-light-driven photoactive materials have drawn much attention owing to their great potential in handling environment and energy crisis. In this work, Z-scheme Bi 2 S 3 /nitrogen-doped graphene quantum dots (NGQDs) with superior photoelectric conversion efficiency were designed and fabricated, which demonstrated enhanced photoactivity compared with Bi 2 S 3 owing to the improved separation efficiency of photogenerated electron and hole pairs. The emphasis was put on designing Z-scheme Bi 2 S 3 /NGQDs, and then the mechanism of Z-scheme charge transfer mode was verified by the electron spin resonance (ESR) technique. On this basis, the proposed sensor exhibited a wide linear range of 0.1–120 nM and a detection limit of 0.03 nM (S/N = 3) for SDM, with high sensitivity (0.075 μA nM –1), good selectivity and stability. Moreover, the proposed PEC aptasensor using Bi 2 S 3 /NGQDs as the photoelectrode achieved sensitive and selective determination of sulfadimethoxine in milk samples. This work could provide some ideas for designing other Z-scheme photoactive species and insights into the charge transfer mechanism of Z-scheme. Furthermore, the promising applicability of PEC aptasensor using photoactive species could be extended to other accurate monitoring for contaminants. Highlights • A Z-scheme type Bi 2 S 3 /NGQDs heterojiunction was designed and construced. • The resulted Bi 2 S 3 /NGQDs showed superior photo-electric conversion efficiency. • ESR technique was used to verify the Z-scheme charge transfer mode of Bi 2 S 3 /NGQDs. • A PEC sulfadimethoxine aptasensor was fabricated based on photoactive Bi 2 S 3 /NGQDs. • The proposed PEC aptasensor exhibited a wider linear range and lower detection limit. [ABSTRACT FROM AUTHOR]

Abstract Developing effective sensing method for trace analysis of ampicillin (AMP) is urgent and significant due to its residue possess serious threats to human health. Herein, a p-n heterojunction, on the basis of p-type BiFeO 3 nanoparticles coupled n-typed ultrathin graphite-like carbon nitride (utg-C 3 N 4) nanosheets, has been designed and synthesized via a simple electrostatic interaction strategy. Such p-n heterojunction has two advantages: one is capable to narrow the band gap of photoactive materials from 2.20 eV of BiFeO 3 down to 2.04 eV of BiFeO 3 /utg-C 3 N 4 , leading to improve the efficiency of visible light utilization; and the other is to facilitate the charge separation rate, resulting in the boosted photoelectrochemical (PEC) performance of BiFeO 3 /utg-C 3 N 4. Under visible light illumination, the photocurrent of the resulted BiFeO 3 /utg-C 3 N 4 was 7.0-fold enhanced than that of pure BiFeO 3 nanoparticles, and indeed 2.3-fold enhanced comparing to BiFeO 3 /bulk-C 3 N 4. Based on excellent PEC properties of BiFeO 3 /utg-C 3 N 4 , an on-off-on PEC aptasensor was successfully fabricated for ampicillin (AMP) determination with highly selectivity and sensitivity. The fabricated PEC aptasensor exhibited excellent PEC performance with a broad linear in the range from 1 × 10–12 mol L–1 to 1 × 10−6 mol L–1 as well as a low detection limit of 3.3 × 10–13 mol L–1 (S/N = 3), and also good feasibility in real sample. The excellent analytical performance indicated that PEC aptasensor on the basis of the visible light driven BiFeO 3 /utg-C 3 N 4 heterojunction can provide a promising biosensor platform for sensitive detection AMP in food and environment analysis. Highlights • The BiFeO 3 /utg-C 3 N 4 p-n heterostructure was facile constructed by electrostatic interaction. • The photocurrent intensity BiFeO 3 /utg-C 3 N 4 exhibits 7.0-fold and 2.3-fold enhanced than BiFeO 3 and BiFeO 3 /bulk-C 3 N 4. • An on-off-on PEC ampicillin aptasensor was successfully fabricated. • The proposed sensitive ampicillin aptasensor exhibits a wide linear range and low detection limit. [ABSTRACT FROM AUTHOR]

Oxygen defect-engineered is an important strategy to improve the photoelectric activity of materials. Herein, a facile one-pot solvothermal method was utilized to synthesize visible light-responsive photoactive Bi 2 MoO 6 nanoparticles anchored boron and nitrogen co-doped graphene (BNG) nanosheets nanocomposites with oxygen vacancy. The incorporation of BNG nanosheets increased the oxygen vacancies amounts on Bi 2 MoO 6 remarkably, and the presences of oxygen vacancies can be beneficial to broaden the absorption range. The absorption edge of Bi 2 MoO 6 /BNG was widened from 500 nm to 550 nm compared to Bi 2 MoO 6 , and the charge transfer was accelerated to improve the photoactive of Bi 2 MoO 6 /BNG. Under visible light illumination, the photoelectrochemical (PEC) response of the as-prepared Bi 2 MoO 6 /BNG was 11.6-fold, 6.7-fold, 3.1-fold and 2.4-fold higher than that of pristine Bi 2 MoO 6 , Bi 2 MoO 6 /graphene, Bi 2 MoO 6 /nitrogen doped graphene and Bi 2 MoO 6 /boron doped graphene. Using Bi 2 MoO 6 /BNG nanocomposites with the superior PEC performance as photoactive materials in combination with specifically recognized lincomycin (LIN) aptamer, a highly efficient PEC aptasensor was successfully constructed for sensitive analysis of LIN. Under optimal conditions, the proposed PEC aptasensor exhibited excellent analytical performance for LIN with a wide linear response of 1 × 10−11 to 1 × 10−6 mol L−1 along with a low detection limit of 3.7 × 10−12 mol L−1 (defined as S / N = 3). The as-prepared Bi 2 MoO 6 /BNG nanocomposites exhibit excellent visible light response and PEC performance, indicating its potential applications in PEC biosensor. • Oxygen vacancy engineered Bi 2 MoO 6 /BNG was prepared by one-pot for the first time. • The photocurrent of Bi 2 MoO 6 /BNG was greatly enhanced compared with pristine Bi 2 MoO 6 , Bi 2 MoO 6 /G, Bi 2 MoO 6 /NG and Bi 2 MoO 6 /BG. • A highly efficient PEC lincomycin aptasensor was successfully established. • The proposed aptasensor exhibited excellent superior analytical performance for lincomycin detection. [ABSTRACT FROM AUTHOR]

Carbendazim (CBZ) has been widely used in agricultural production to control fruits and vegetables diseases, but it can also destroy the human endocrine system. Therefore, sensitive detection of CBZ has attracted increasing attention worldwide. In this study, Pd nanoparticles (Pd NPs) decorated on CdS microsphere (Pd NPs/CdS) was prepared by the in-situ photoreduced method, and based on the surface plasmon resonance (SPR) effect of noble metal and Schottky junction between Pd nanoparticles (Pd NPs) and CdS microsphere, the photocurrent after introducing Pd NPs is 7.7 times higher than that of bare CdS microsphere. In view of the outstanding photoelectrochemical (PEC) performance of Pd NPs/CdS and the high specificity of the aptamer, the as-fabricated PEC aptasensor for CBZ detection possesses the excellent detection performance including a broad linear ranging from 1.0 × 10−12 to 1.0 × 10−6 mol/L as a low detection limit of 3.3 × 10−13 mol/L (S/N = 3). Furthermore, the PEC aptasensor was used for determination of lettuce samples from actual agricultural products with satisfactory results. • Schottky junction was formed by photoreduction with Xe lamp irradiation for 5 min. • The Schottky junction promoted the separation of photogenerated electron-hole. • SPR effect was used to increase CdS microspheres to capture visible light. • The PEC aptasensor exhibited excellent selectivity and sensitivity for Carbendazim. [ABSTRACT FROM AUTHOR]

Dye sensitization is an alternative strategy to improve photoelectric activity of semiconductors and, particularly, to enhance the activity towards visible light domain. Herein, an artificial Z-scheme bipyridine ruthenium (Ru(bpy) 3 2+) sensitizing narrow-gap bismuth oxy-iodide (BiOI) microspheres was constructed by a simple electrostatic interaction strategy for the first time. The electrochemical impedance spectroscopy (EIS) and photoluminescence (PL) analysis showed that this design of such Z-scheme structure was helpful to enhance the interfacial charge transfer and improve the photoelectric conversion efficiency. In addition, due to the sensitization of Ru(bpy) 3 2+, the band gap was narrowed from 1.8 eV of BiOI microspheres to 1.3 eV of BiOI/Ru(bpy) 3 2+ microspheres, leading to improve the utilization of visible light. So that, the photocurrent of the resulted BiOI/Ru(bpy) 3 2+ was 13.0 times that of pure BiOI microspheres. In view of the outstanding photoelectrochemical (PEC) performance of BiOI/Ru(bpy) 3 2+ and the high specificity of the aptamer, the PEC aptasensor for ampicillin (AMP) merits the excellent detection performance including a broad linear ranging from 1 × 10–7 nM to 100 nM as well as a low detection limit of 3.3 × 10–8 nM (S/N = 3). This work not only provides a novel way to construct and design highly efficient photoactive materials for PEC detection, but also broadens the application of Z-scheme in the field of sensing. • BiOI/Ru(bpy) 3 2+ microspheres were successfully prepared, showing a 13-fold photocurrent intensity compared to pure BiOI. • The Z-scheme configuration was helpful to enhance the interfacial charge transfer. • As a sensitizer, Ru(bpy) 3 2+ extended the spectral response of BiOI/Ru(bpy) 3 2+, thus improving the visible light utilization. • The fabricated PEC aptasensor exhibited good selectivity and sensitivity for ampicillin detection. [ABSTRACT FROM AUTHOR]