•A novel universal signal amplification (USA) probe-based ECL assay was established.•The assay was used to detect pathogenic bacteria.•The usage of capture probes improved the specificity and sensitivity of the assay.•Ru(bpy)32 +-labeled USA probe can be used in detection of different target genes.A novel universal signal amplification (USA) probe-based electrochemiluminescence (ECL) assay for sensitive detection of pathogenic bacteria was developed. In this assay, a series of capture probes (CPs) containing two distinctly functional parts were carefully designed. One part was used to specifically recognize different regions of single-stranded (ss) target DNA in order to improve the accuracy and specificity of the assay. The other part was used to hybridize with USA probe so as to amplify the ECL signal and thus improve the sensitivity of the assay. Furthermore, the USA probe can be used to detect different target genes due to its universal sequence so as to reduce the cost of the assay. The method was applied to detect Staphylococcus aureus (S. aureus). The experimental results showed that the detection limit was 100 fM of asymmetric PCR products. The method holds great promise in pathogenic bacteria detection due to its accuracy, specificity, sensitivity and low-cost.

We developed a hybrid fluorescent material using amino functional mesoporous hollow silica microspheres (MHSM) encapsulated with CdTe quantum dots (QDs). The amino group plays a key role in immobilizing both QDs and formaldehyde in the inner mesoporous hole of MHSM. The present QDs-MHSM shows good fluorescence property and excellent photostability after ultrasonic irradiation in water for several times or stewing for more than 30 days. Its fluorescence intensity is quenched rapidly in the presence of formaldehyde but not by interference with commonly organic solvents. Under the optimal experimental conditions, such as the response time and pH of the solution, a sensitive fluorescence method was developed for the analysis of formaldehyde in seafood based on fluorescence quenching of QDs-MHSM. The linear response range of formaldehyde (R2 = 0.9997) ranged from 0.2 to 15.5 mg L−1 and the detection limit (S/N = 3) was as low as 0.07 mg L−1. The recovery was 99.5% with a relative standard deviation less than 5.0%, which was consistent with that obtained by the China National Standard colorimetric method, suggesting the potential application of this sensitive and simple method in food quality monitoring or other relative fields.

A series of substituted benzoyl modified β-cyclodextrins, including mono-6-O-(p-methylbenzoyl)-β-CD (1), mono-6-O-(m-methylbenzoyl)-β-CD (2), mono-6-O-(o-methylbenzoyl)-β-CD (3), mono-6-O-(p-methoxylbenzoyl)-β-CD (4), mono-6-O-(m-methoxylbenzoyl)-β-CD (5), mono-6-O-(o-methoxylbenzoyl)-β-CD (6), mono-6-O-(m, p-dimethoxylbenzoyl)]-β-CD (7), mono-6-O-(o,m-dimethoxylbenzoyl)-β-CD (8), and mono-(6-O-benzoyl)-β-CD (9) were synthesized and their inclusion properties were studied by using fluorescence spectroscopy. The binding constants (Ka) of the modified β-CD derivatives with 2-p-toluidinylnaphthalene-6-sulfonate (TNS) were determined on the basis of the fluorescence spectroscopy. The effect of types and location of substituted groups of the benzene ring of the modified β-cyclodextrins on the binding property was discussed. Results indicated that the substituents had significant influences on the binding abilities of modified β-cyclodextrins.

The inclusion behavior of cis-cyclooctene, cis, cis-1, 3-cyclooctadiene and cis, cis-1, 5-cyclooctadiene with β-cyclodextrin (β-CD) was studied by using 1H NMR method in D2O/CD3OD solution and PM3 quantum-chemical simulation in vacuum. The experimental results indicate that each guest molecule penetrates deeply into β-CD cavity and forms equimolecular inclusion complex with the host. The association constants of the complexes were determined by non-linear least-square method on the bases of the conversion-dependent chemical shift of two protons of the host molecule. The inclusion process and the most probable structure of the inclusion complexes were simulated using PM3 energy scanning and optimization. The trend of stability of the three inclusion complexes deduced from their calculated stabilization energies agrees well with the order of their association constants obtained from NMR experiments.