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Detection of cyanide (CN-) ion is of essential importance due to its high toxicity to human life. Herein, we developed a gold nanoclusters (AuNCs)-peroxyoxalate chemiluminescence (CL) system for ultrasensitive detection of CN- in environmental water samples. Bis (2,4,5-trichloro-6-carbopentoxyphenyl) oxalate (CPPO)-hydrogen peroxide (H 2 O 2) CL reaction was utilized to produce high energy intermediates, namely energy donors, and AuNCs served as the acceptors to harvest the energy via CL resonance energy transfer (CRET) process. Besides, it was demonstrated that AuNCs also could act as a catalyst to enhance the generation of the high energy intermediate; and the AuNCs also had an aggregation induced emission (AIE) effect in the organic solvent that was used in CPPO-based CL system. In the presence of CN-, AuNCs can be etched by CN- due to the Elsner complexation reaction between CN- and AuNCs, and thus both of the quantum yield and catalytic activity decreased remarkably. As a result, significant quenching of CPPO-AuNCs CL was observed. The CL intensity decreased linearly in the concentration range of 2.5–125 μg/L CN-, and the detection limit was calculated to be 0.55 μg/L, 10-fold lower than that obtained by the fluorescent sensing of AuNCs. The relative standard deviation was 4.3% for seven parallel measurements of 100 μg/L CN-. It also exhibited high selectivity and favorable anti-interference capability. The sensing system was used for detection of CN- in five standard water samples, and the analytical results were in good agreement with the certified values. Overall, the simple and sensitive CL sensing platform offers a promising tool for convenient detection of CN- in environmental water samples. [Display omitted] • A CPPO-AuNCs CL system was developed for ultrasensitive detection of CN- in environmental water samples. • The etching of AuNCs by CN- lead to the decrease of both quantum yeilds and catalytic activity. • The quenching effect allow detection of 2.5–125 μg/L CN- withi an LOD down to 0.26 μg/L. [ABSTRACT FROM AUTHOR]

Detection of cyanide (CN-) ion is of essential importance due to its high toxicity to human life. Herein, we developed a gold nanoclusters (AuNCs)-peroxyoxalate chemiluminescence (CL) system for ultrasensitive detection of CN- in environmental water samples. Bis (2,4,5-trichloro-6-carbopentoxyphenyl) oxalate (CPPO)-hydrogen peroxide (H 2 O 2) CL reaction was utilized to produce high energy intermediates, namely energy donors, and AuNCs served as the acceptors to harvest the energy via CL resonance energy transfer (CRET) process. Besides, it was demonstrated that AuNCs also could act as a catalyst to enhance the generation of the high energy intermediate; and the AuNCs also had an aggregation induced emission (AIE) effect in the organic solvent that was used in CPPO-based CL system. In the presence of CN-, AuNCs can be etched by CN- due to the Elsner complexation reaction between CN- and AuNCs, and thus both of the quantum yield and catalytic activity decreased remarkably. As a result, significant quenching of CPPO-AuNCs CL was observed. The CL intensity decreased linearly in the concentration range of 2.5–125 μg/L CN-, and the detection limit was calculated to be 0.55 μg/L, 10-fold lower than that obtained by the fluorescent sensing of AuNCs. The relative standard deviation was 4.3% for seven parallel measurements of 100 μg/L CN-. It also exhibited high selectivity and favorable anti-interference capability. The sensing system was used for detection of CN- in five standard water samples, and the analytical results were in good agreement with the certified values. Overall, the simple and sensitive CL sensing platform offers a promising tool for convenient detection of CN- in environmental water samples. [Display omitted] • A CPPO-AuNCs CL system was developed for ultrasensitive detection of CN- in environmental water samples. • The etching of AuNCs by CN- lead to the decrease of both quantum yeilds and catalytic activity. • The quenching effect allow detection of 2.5–125 μg/L CN- withi an LOD down to 0.26 μg/L. [ABSTRACT FROM AUTHOR]

Fluorescence resonance energy transfer (FRET) is a reliable, sensitive, and robust assay method for detection of many biological targets. However, it generally needs an externally-introduced label to form the donor-acceptor pair, which could alter the accuracy of the detection. To address this issue, we report herein the FRET-based reactive copper ion sensors by using in situ fluorescent proteins (FP) of human urine or blood serum as the energy donor. Using Bull Serum Albumin (BSA) as model proteins, the sensor exhibits a remarkably fluorescence enhancement when BSA binds to the surface of copper clusters (Cu NCs) base on electrostatic interaction. Conversely, low fluorescence enhancement is observed without using BSA. As proof-of-principle, this positive approach is directly applied to detect Cu 2+ using urine as the energy donor, accompanying with a signal enhancement by two factors and low detection limit of 0.5 μM Cu 2+ . Moreover, the proposed sensor could be applied in other complex environments, such as blood serum or cell culture medium. Consequently, the effectiveness, simplicity and diversity of our proposed strategy enable the development of a class of probes toward complex human environment for rapid, sensitive, and selective detection of targets. [ABSTRACT FROM AUTHOR]

Colloidal quantum dots (QDs) have been widely used as fluorescent labeling materials in the field of in vitro diagnostics (IVD). In spite of the significant development of direct single-signal response fluorescent immunosensors, it is still a challenge to obtain the high accuracy and sensitivity of quantitative results of these sensors due to the influence of several factors unrelated to the analysis. Herein, we present a delicate design and synthesis of dual-color QDs bilayer nanobeads (red and green QDs nanobeads, R&G-QD nanobeads), achieving the precisely control of growth of the silicon layer with different proportions of ammonia, and inhibiting fluorescence resonance energy transfer (FRET) successfully. The dual-color QDs bilayer nanobeads have realized dual-channel detection (the acquisition of two emission wavelengths) of the target, and avoided the problems of low analytical accuracy and imprecise sensitivity of single-signal response. A proof-of-concept demonstration of a fluorescence-linked immunosorbent assay (FLISA) platform is conducted for the quantitative detection of prostate-specific antigen (PSA) with a sensitivity of 49 pg/mL and a linear range of 0.2–800 ng/mL. The dual-color QDs bilayer nanobeads FLISA platform with high sensitivity and accuracy holds great potential for early diagnosis of cancer or other diseases and provides a new approach for IVD. [Display omitted] • Dual-color QDs bilayer nanobeads were designed to synthesize by layer-by-layer assembly method. • Controlled growth of alternate red and green QD layers on pre-synthesized SiO 2 beads can suppress energy transfer. • Such dual-color QDs nanobeads deliver dual single calibration and can avoid errors caused from the single signal response. • A proof-of-concept demonstration of a FLISA platform is conducted for detecting PSA with high sensitivity and accuracy. [ABSTRACT FROM AUTHOR]