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A highly sensitive and selective electrogenerated chemiluminescence (ECL) biosensor was developed for the determination of matrix metalloproteinase 3 (MMP-3) in serum via the target-induced cleavage of an oligopeptide. One ECL probe (named as Ir-peptide) was synthesized by covalently linking a new cyclometalated iridium(III) complex ([(3-pba)2Ir(bpy-COOH)](PF6)) (3-pba = 3-(2-pyridyl) benzaldehyde, bpy-COOH = 4′-methyl-2,2′-bipyridine-4-carboxylic acid) with an oligopeptide (CGVPLSLTMGKGGK). An ECL biosensor was fabricated by firstly casting Nafion and gold nanoparticles (AuNPs) on a glassy carbon electrode and then self-assembling both of the ECL probes, 6-mercapto-1-hexanol and zwitterionic peptide, on the electrode surface, from which the AuNPs could be used to amplify the ECL signal and Ir-peptide could serve as an ECL probe to detect the MMP-3. Thanks to the MMP-3-induced cleavage of the oligopeptide contributing to the decrease in ECL intensity and the amplification of the ECL signal using AuNPs, the ECL biosensor could selectively and sensitively quantify MMP-3 in the concentration range of 10–150 ng·mL−1 and with both a limit of quantification (26.7 ng·mL−1) and a limit of detection (8.0 ng·mL−1) via one-step recognition. In addition, the developed ECL biosensor showed good performance in the quantization of MMP-3 in serum samples, with a recovery of 92.6% ± 2.8%–105.6% ± 5.0%. An increased level of MMP-3 was found in the serum of rheumatoid arthritis patients compared with that of healthy people. This work provides a sensitive and selective biosensing method for the detection of MMP-3 in human serum, which is promising in the identification of patients with rheumatoid arthritis. [ABSTRACT FROM AUTHOR]

We report the rational design of the matrix‐free carbon dots (C‐dots) with long wavelength and wavelength‐tunable room‐temperature phosphorescence (RTP). Taking advantage of microwave‐assisted heating treatment, three RTP C‐dots in boric acid (BA) composites are synthesized by using diethylenetriaminepentakis (methylphosphonic acid) as a multiple‐sites crosslink agent, a moderately acid catalyst and P source; phenylenediamines (either o‐PD, m‐PD, or p‐PD, respectively) as building block while BA as a carbonization‐retardant matrix. After the water‐soluble BA matrix is removed by dialysis, three matrix‐free C‐dots are obtained with RTP emission at 540, 550 and 570 nm under an excitation wavelength of 365 nm. Alterations of RTP emission of three matrix‐free C‐dots are ascribed to the difference in their particle size and band gap from n‐π* transition. Furthermore, the application of three matrix‐free C‐dots are successfully performed in information encryption and decryption. [ABSTRACT FROM AUTHOR]

Main observation and conclusion: A single particle‐based confocal laser scanning microscopy was developed for the visual detection of copper ions in confined space. A fluorescence microparticle, named AuNCs/ZIF‐8, was synthesized by coating gold nanoclusters (AuNCs) onto the outer surface of zeolitic imidazolate framework‐8 (ZIF‐8). The morphology and solid‐state fluorescence property of AuNCs/ZIF‐8 were characterized by scanning electron microscopy and fluorescence technique. The AuNCs/ZIF‐8 exhibits turn‐off responses to copper ions via fluorescence quenching in the range of 2—15 μmol·L–1 with a detection limit of 0.9 μmol·L–1. More importantly, the distribution of AuNCs on single ZIF‐8 crystal and the fluorescence quenching dynamics on single AuNCs/ZIF‐8 were visualized by 3D‐reconstructed fluorescence imaging. Different distribution of AuNCs on the different surfaces of single ZIF‐8 crystal and similar fluorescence quenching dynamics on the different surfaces of single AuNCs/ZIF‐8 were obtained. These results offer insights into the nature of the fluorescence active sites and the fluorescence quenching dynamics on a single fluorescence particle, which also opens up new opportunities for in situ target biomolecule analysis in confined space. [ABSTRACT FROM AUTHOR]

Main observation and conclusion: A single particle‐based confocal laser scanning microscopy was developed for the visual detection of copper ions in confined space. A fluorescence microparticle, named AuNCs/ZIF‐8, was synthesized by coating gold nanoclusters (AuNCs) onto the outer surface of zeolitic imidazolate framework‐8 (ZIF‐8). The morphology and solid‐state fluorescence property of AuNCs/ZIF‐8 were characterized by scanning electron microscopy and fluorescence technique. The AuNCs/ZIF‐8 exhibits turn‐off responses to copper ions via fluorescence quenching in the range of 2—15 μmol·L–1 with a detection limit of 0.9 μmol·L–1. More importantly, the distribution of AuNCs on single ZIF‐8 crystal and the fluorescence quenching dynamics on single AuNCs/ZIF‐8 were visualized by 3D‐reconstructed fluorescence imaging. Different distribution of AuNCs on the different surfaces of single ZIF‐8 crystal and similar fluorescence quenching dynamics on the different surfaces of single AuNCs/ZIF‐8 were obtained. These results offer insights into the nature of the fluorescence active sites and the fluorescence quenching dynamics on a single fluorescence particle, which also opens up new opportunities for in situ target biomolecule analysis in confined space. [ABSTRACT FROM AUTHOR]

Designing efficient room‐temperature phosphorescence (RTP) carbon dots (C‐dots) without the need of an additional matrix is important for various applications. Herein, matrix‐free and highly efficient C‐dots with yellow‐green RTP emission have been successfully synthesized towards information encryption and decryption. Phytic acid (PA) and triethylenetetramine are used as molecular precursors, and a facile microwave‐assisted heating method is selected as synthesis method. The obtained C‐dots exhibit a maximum phosphorescence emission at around 535 nm under an excitation wavelength of 365 nm and a long average lifetime up to 750 ms (more than 9 s to the naked eye). PA containing six phosphate groups and serving as P source plays a significant role in producing the RTP C‐dots. Furthermore, potential applications of the RTP C‐dots in the field of information encryption and decryption are successfully demonstrated. [ABSTRACT FROM AUTHOR]

The development of new methods for the detection of redox cycle is important for biological and clinical diagnoses. Here, a new cyclometalated iridium complex, (4-(2-pyridyl) benzaldehyde)2Ir (5-chloro-1,10-phenanthroline) ([(4-pba)2Ir(5-Cl-phen)]PF6, probe 1), has been synthesized and applied to rapid, sensitive, and reversible detection and imaging of redox cycle HSO 3 - /H2O2 in living cells. The probe 1 is synthesized by using 4-(2-pyridyl) benzaldehyde as main ligand and 5-chloro-1,10-phenanthroline as ancillary ligand. Probe 1 exhibited "off–on–off" photoluminescence (PL) signal change in response to HSO 3 - and H2O2 in aqueous solution within 1 min. The change of PL intensity is proportional to HSO 3 - concentration from 40 μM to 300 μM and to H2O2 concentration from 40 μM to 260 μM. The detection limit is 10 μM for HSO 3 - and 20 μM for H2O2. Additionally, probe 1 was applied to detect HSO 3 - in food samples with satisfactory results. More importantly, PL imaging of HeLa cells indicates that probe 1 is able to image redox cycle HSO 3 - /H2O2 in living cells. [ABSTRACT FROM AUTHOR]

The development of new methods for the detection of redox cycle is important for biological and clinical diagnoses. Here, a new cyclometalated iridium complex, (4-(2-pyridyl) benzaldehyde) 2 Ir (5-chloro-1,10-phenanthroline) ([(4-pba) 2 Ir(5-Cl-phen)]PF 6 , probe 1 ), has been synthesized and applied to rapid, sensitive, and reversible detection and imaging of redox cycle HSO 3 - /H 2 O 2 in living cells. The probe 1 is synthesized by using 4-(2-pyridyl) benzaldehyde as main ligand and 5-chloro-1,10-phenanthroline as ancillary ligand. Probe 1 exhibited "off-on-off" photoluminescence (PL) signal change in response to HSO 3 - and H 2 O 2 in aqueous solution within 1 min. The change of PL intensity is proportional to HSO 3 - concentration from 40 μM to 300 μM and to H 2 O 2 concentration from 40 μM to 260 μM. The detection limit is 10 μM for HSO 3 - and 20 μM for H 2 O 2 . Additionally, probe 1 was applied to detect HSO 3 - in food samples with satisfactory results. More importantly, PL imaging of HeLa cells indicates that probe 1 is able to image redox cycle HSO 3 - /H 2 O 2 in living cells.