A flavonoid salt probe for distinguishing between tumor and normal cells.

YH-2 represents an innovative, non-invasive fluorescent probe featuring a structure based on flavonoid onium salts. It is characterized by a well-suited Stokes shift and emits in the near-infrared (NIR) wavelength range. Its capacity to distinguish between HeLa cells, HepG2 cells, and LO2 cells is attributed to differential intracellular viscosity. Experimental results validate the heightened viscosity of organelles, such as the endoplasmic reticulum (ER), mitochondria and lysosomes in tumor cells compared to LO2 cells. Of paramount importance, YH-2 demonstrates the capability to swiftly image tumors within a mere 20 min following tail vein injection and this imaging ability can be sustained for an extended period of up to 5 h. This method offers a potential tumor diagnostic strategy in vivo.

A self-assembly aptasensor based on thick-shell quantum dots for sensing of ochratoxin A.

A novel self-assembling aptasensor was fabricated by precisely attaching three phosphorothioate-modified capture aptamers onto a single thick-shell quantum dot in a controllable manner for monitoring of ochratoxin A (OTA), a poisonous contaminant widespread in foodstuffs. Herein, CdSe/CdS QDs coated in ten layer CdS shells were synthesized using a continual precursor injection method. Analysis of the prepared CdSe/CdS QDs showed a zinc-blende structure, high photoluminescence quantum yields (>80%), and a photoemission peak with a narrow full-width at half-maximum (about 29 nm), all qualities that render them as a superior choice for optical applications. By adjusting the number of phosphorothioate bases in the anchor domain, the tunable-valency aptasensor was able to self-assemble. In the sensing strategy, the thick-shell quantum dot was provided as an acceptor while OTA itself was used as a donor. In the presence of OTA, the capture aptamers drive the aptasensor function into a measurable signal through a fluorescence resonance energy transfer (FRET) system. The newly developed aptasensor had a detection limit as low as 0.5 ng mL(-1), with a linear concentration in the range of 1 to 30 ng mL(-1), and therefore meets the requirements for rapid, effective, and anti-interference sensors for real-world applications. Moreover, the high quality thick-shell QDs provide an ideal alternative for highly sensitive imaging and intensive illumination in the fields of biotechnology and bioengineering.

A gold-based nanobeacon probe for fluorescence sensing of organophosphorus pesticides.

A nanomaterials-based novel molecular beacon has attracted growing attentions in fluorescent assays as many nanomaterials possess excellent quenching efficiency. In this work, a gold-based nanobeacon probe was established to detect organophosphorus pesticides for the first time. The constructed gold-based nanobeacon acted as a signal indicator and could display the decreasing of the intensity in the presence of targets, which competitively bound to single strand DNA. To achieve a high sensitive probe, some parameters including solution pH, temperature and reaction time were investigated and optimized. The gold-based nanobeacon probe assay was proved to be rapid and sensitive to achieve a detection limit of 0.035 µM for isocarbophos, 0.134 µM for profenofos, 0.384 µM for phorate and 2.35 µM for omethoate, respectively. The prepared nanobeacon effectively reduced the background and improved the detection sensitivity and selectivity. The probe is stable, easy to operate and does not need sophisticated instruments. These features makes the probe feasible for screening trace organophosphorus pesticides in real samples.

[Contamination level of aflatoxin B1 in lotus seeds rapid screening by indirect competitive ELISA method].

A simple and cost-effective indirect competitive enzyme-linked immune sorbent assay (ic-ELISA) was developed to rapidly screen the content of aflatoxin B1 (AFB1) in lotus seeds, and the results were confirmed by ultra-fast liquid chromatography-tandem mass spectrometry( UFLC-MS/MS). Matrix-matched calibration expressed a good linearity ranging from 0. 171 to 7. 25 µg · L(-1) for AFB, with R2 > 0.978. The medium inhibitory concentration( IC50 ) for AFB1 was 1.29 µg · L(-1), the recovery for AFB1 was 74.73% to 126.9% with RSD < 5%, and the limit of detection (IC10) was 0.128 µg · L(-1). The developed ic-ELSIA method was applied to rapid analysis of AFB, in 20 lotus seeds samples and the results indicated that the contents of AFB, in samples 1-15 were in the range of 1. 19- 115. 3 µg · kg(-1) and in 40% of the samples exceeded the legal limit(5 µg · kg(-1)), while the contamination rate of AFB, in samples 16-20 was 40%. Pearson correlation coefficient(r) reached 0.997 for AFB1 content in the samples detected by ic-ELSIA and UFLC-MS/MS methods. The results proved that the developed ic-ELISA method is simple, sensitive and reliable, and can be used for rapid and high-throughput screening of AFB1 in lotus seeds

Ultra-fast liquid chromatography with tandem mass spectrometry determination of ochratoxin A in traditional Chinese medicines based on vortex-assisted solid-liquid microextraction and aptamer-affinity column clean-up.

A rapid, selective, and sensitive ultra-fast liquid chromatography with tandem mass spectrometry method was developed for the determination of ochratoxin A in traditional Chinese medicines based on vortex-assisted solid-liquid microextraction and aptamer-affinity column clean-up. Through optimizing the sample pretreatment procedures and chromatographic conditions, good linearity (r(2) ≥ 0.9993), low limit of detection (0.5-0.8 µg/kg), and satisfactory recovery (83.54-94.44%) expressed the good reliability and applicability of the established method in various traditional Chinese medicines. Moreover, the aptamer-affinity column, prepared in-house, showed an excellent feasibility owing to its specific identification of ochratoxin A in various kinds of selected traditional Chinese medicines. The maximum adsorption amount and applicability value were 188.96 ± 10.56 ng and 72.3%, respectively. The matrix effects were effectively eliminated, especially for m/z 404.2→358.0 of ochratoxin A. The application of the developed method for screening the natural contamination levels of ochratoxin A in 25 random traditional Chinese medicines on the market in China indicated that only eight samples were contaminated with low levels below the legal limit (5.0 µg/kg) set by the European Union. This study provided a preferred choice for the rapid and accurate monitoring of ochratoxin A in complex matrices.