Zhongying Liu

A rapid immunomagnetic beads-based immunoassay for the detection of β-casein in bovine milk

An immunomagnetic beads-based enzyme-linked immunosorbent assay (IMBs-ELISA) was developed for the detection of β-casein in bovine milk. Immunomagnetic beads (IMBs) were employed as the solid phase. The anti-β-casein monoclonal antibody (McAb) bound to IMBs was used as capture probe and an anti-β-casein polyclonal antibody (PcAb), labelled with horseradish peroxidase (HRP), was employed as detector probe. Three reaction and two washing steps were needed. Each reaction needed 10 min or less, which significantly shortened detection compared with classic sandwich ELISA. β-Casein in bovine milk was detected across a linear range (2-128 μg mL(-1)). Application results were in accordance with the Kjejdahl method, which suggests the IMBs-ELISA is rapid and reliable for the detection of β-casein in bovine milk.

Gold nanoparticle aggregation-based colorimetric assay for β-casein detection in bovine milk samples

Traditional Kjeldahl method, used for quality evaluation of bovine milk, has intrinsic defects of time-consuming sample preparation and two analyses to determine the difference between non-protein nitrogen content and total protein nitrogen content. Herein, based upon antibody functionalized gold nanoparticles (AuNPs), we described a colorimetric method for β-casein (β-CN) detection in bovine milk samples. The linear dynamic range and the LOD were 0.08-250 μg mL(-1), and 0.03 μg mL(-1) respectively. In addition, the real content of β-CN in bovine milk was measured by using the developed assay. The results are closely correlated with those from Kjeldahl method. The advantages of β-CN triggered AuNP aggregation-based colorimetric assay are simple signal generation, the high sensitivity and specificity as well as no need of complicated sample preparation, which make it for on-site detection of β-CN in bovine milk samples.

Double-antibody based immunoassay for the detection of β-casein in bovine milk samples

The concentration of casein (CN) is one of the most important parameters for measuring the quality of bovine milk. Traditional approach to CN concentration determination is Kjeldahl, which is an indirect method for determination of total nitrogen content. Here, we described a double-antibody based direct immunoassay for the detection of β-CN in bovine milk samples. Monoclonal antibody (McAb) was used as capture antibody and polyclonal antibody (PcAb) labelled with horseradish peroxidase (HRP) as detection antibody. With the direct immunoassay format, the linear range of the detection was 0.1-10.0 μg mL(-1). The detection limit was 0.04 μg mL(-1). In addition, the concentration of β-CN in real bovine milk samples has been detected by the developed immunoassay. There was a good correlation between the results obtained by the developed technique and Kjeldahl method from commercial samples. Compared to the traditional approach, the advantage of the assay is no need of time-consuming sample pretreatment.

Urinary metabolomics study on the anti-inflammation effects of flavonoids obtained from Glycyrrhiza

Rheumatoid arthritis (RA) is a chronic disease with pain, swelling, and limitation in the motion and function of multiple joints thus leading to high disability. Previous studies have shown that flavonoids and saponins are the most abundant and active constituents in Glycyrrhiza, which possess a wide range of pharmacological effects such as anti-inflammatory, antioxidant and anti-bacteria. But the mechanisms of those actions are not entirely clear. In order to clarify the mechanisms of those actions, the pharmacodynamical assessments of extraction of water-soluble components and flavonoids and saponins obtained from Glycyrrhiza were investigated. Combining the pharmacodynamical researches, we found that flavonoids obtained from Glycyrrhiza had more significant therapeutic effects on acute inflammation, chronic inflammation and inflammatory pain than that of extraction of water-soluble components and saponins obtained from Glycyrrhiza. The results indicated that flavonoids are the main medicinal ingredients in Glycyrrhiza. In order to further investigate the mechanism of the action of flavonoids in Glycyrrhiza on treating RA, a urine metabolomics method based on ultra high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) was established to observe the metabolic variations in adjuvant-induced arthritis (AIA) rats and investigate the therapeutic effect of flavonoids in Glycyrrhiza on RA. As a result, twenty potential biomarkers were found by comparison with the model group (MG) and flavonoid treated group (FG). We associated these compounds with related metabolic pathways, the results showed that these biomarkers were mainly associated with purine metabolism, taurine and hypotaurine metabolism, tryptophan metabolism, phenylalanine metabolism, tricarboxylic acid cycle (TCA cycle), pantothenate and coenzyme A (CoA) biosynthesis. The results about the pharmacodynamics and metabolomics provided a theoretical basis for clarifying the mechanism of flavonoids in Glycyrrhiza in the treatment of RA.

Study on Urine Metabolic Profile of Aβ25–35-Induced Alzheimer's Disease Using UHPLC-Q-TOF-MS

Alzheimers disease (AD) is a progressive neurodegenerative disorder, with no effective method for its treatment so far. The pathogenesis of AD has been reported, but the endogenous metabolic profile and disease-related biomarkers are still not clear. To better understand AD, an AD model induced by injecting β-amyloid 25-35 (Aβ 25-35) solution into bilateral hippocampus was developed on Sprague-Dawley rats. After 8 weeks of modeling, the impairment of spatial learning and memory ability in AD rats were assessed by Morris water maze task. Hematoxylin and eosin staining and immunohistochemistry were used to investigate the pathological changes of hippocampus. The neurotransmitter concentrations in the hippocampus were measured using UHPLC-TQ-MS. Urinary metabolomics based on UHPLC-Q-TOF-MS was established to delineate the alterations of endogenous metabolites in AD rats. The results showed that compared with healthy control rats, AD rats suffered from cognitive dysfunction, hippocampus damage, Aβ formation and tau phosphorylation at 8 weeks after surgery, suggesting that the Aβ25-35-induced AD model was successfully established. In addition, the levels of γ-aminobutyric acid, acetylcholine, glycine, norepinephrine, serotonin, taurine and dopamine decreased and glutamate and aspartic acid increased in hippocampal tissue of AD rats. 45 altered metabolites mainly involved in 8 metabolic pathways were identified as the endogenous biomarkers of AD. According to the analysis of the biological significance of metabolic profiles, the pathogenesis of AD was mainly due to gut microbiome dysbiosis, inhibition of energy metabolism, oxidative stress injury and loss of neuronal protective substances.