A low-field nuclear magnetic resonance DNA-hydrogel nanoprobe for bisphenol A determination in drinking water.

A low-field nuclear magnetic resonance (LF-NMR) DNA-hydrogel (LNDH) nanoprobe was designed for bisphenol A (BPA) determination. It consists of Fe3O4 superparamagnetic iron oxide nanoparticles (SPIONs) and a DNA-hydrogel technology. Fe3O4 SPIONs were encapsulated in the DNA-hydrogel to form an aggregated state. After adding BPA, the gel system transformed into a sol gel due to the target-aptamer specific binding. The coated gathered particles dispersed and thus, the relaxation time T2 declined. The LNDH nanoprobe was developed to realize a simple, sensitive, and effective BPA determination method without repeated magnetic separation steps. Under the optimal experimental conditions, the determination range of the LNDH biosensor was 10-2~102 ng mL-1 and the limit of determination was 0.07 ng mL-1. The LNDH nanoprobe was applied to two kinds of water samples (tap water and bottled water). The recovery ranged from 87.85 to approximately 97.87%. This strategy offered a new method to detect BPA by LF-NMR. It is also expected to be applicable in related fields of food safety determination, environmental monitoring, and clinical diagnosis. Graphical abstract Schematic presentation of LNDH biosensor. Acrydite-modified ssDNA was copolymerized with acrylamide to form linear conjugates PS-A/B, adding aptamer and SPIONs to form DNA-hydrogel. When aptamer captured the target, the hydrogel was destroyed to disperse the coated SPIONs. T2 relaxation time declined.

[Potential toxic effects of TDCIPP on the thyroid in female SD rats].

Objective: To investigate the potential toxic effects and mechanisms of Tris(1; 3-dichloro-2-propyl) phosphate (TDCIPP) on thyroid in female SD rats.Methods: Thirty-two 3-weeks-old female SD rats were randomly divided into normal group(treated with corn oil ), and low/moderate/high-dose group treated with TDCIPP (dissolved in corn oil )(n=8). All rats were treated with corn oil or TDCIPP (50, 100, 250 mg/(kg·d)) once a day during a 21-day period. All rats were sacrificed after the last administration. Serum thyroid stimulating hormone (TSH), 3,3',5-triiodothyronine (T3), 3,3',5,5'-tetraiodothyronine (T4), free 3,3',5,5'-tetraiodothyronine (FT4) were detected with ELISA kit. Morphology of thyroid was observed with hematoxylin and eosin (HE) staining. Expressions of genes and proteins correlate with thyroid were measured respectively by real-time fluorescence quantitative PCR and Western blot. Results: Compared with control group, morphology of thyroid showed follicles irregular arrangement, hypocolloid, and follicular hyperplasia in TDCIPP treatment groups. The levels of serum TSH in low-dose TDCIPP group and T3 in high-dose TDCIPP group were significantly higher than those in control group(P＜0.05). Thyroid stimulating hormone receptor (TSHR) mRNA expression was decreased distinctly in low-dose TDCIPP group, while the expression of thyroperoxidase (TPO) mRNA was increased notably in moderate and high-dose TDCIPP groups(P＜0.05,P＜0.01). Compared with control group, the level of TRß protein was decreased significantly in moderate and high-dose TDCIPP groups, while the expressions of udp-glucuronosyl-transferases (UGTs) and cytochrome-p450-3A1 (CYP3A1) proteins were upregulated notably in TDCIPP treatment groups(P＜0.05). Conclusion: Treated with 50 mg/(kg·d) TDCIPP can cause thyroid hyperplasia, change the levels of thyroid hormones, and disturb thyroid function, therefore, it has toxic effects on the thyroid.