Branched polyethyleneimine-assisted 3-carboxybenzoboroxole improved Wulff-type boronic acid functionalized magnetic nanoparticles for the specific capture of cis-diol-containing flavonoids under neutral conditions.

Flavonoids have shown a variety of biological activities such as antimicrobial, antibacterial, antifungal, antiviral, antiinflammatory, antitumor, antiatherogenic, and antihyperglycemic activities. A lot of important flavonoids contain cis-diols such as rutin (Ru), quercetin (Qu), luteolin (Lu), myricetin (Myr) and baicalein (Ba) and so on. It is necessary to establish a simple, low-cost and efficient purification method for cis-diol-containing flavonoids from plant extracts. Boronate affinity materials are able to reversibly bind the cis-diols via boronic acids by forming a five- or six-membered boronic cyclic ester in aqueous media. However, conventional boronate affinity materials have to be used in alkaline media, which can lead to the oxidation of cis-diols in compounds. In this study, the polyethyleneimine (PEI)-assisted 3-carboxybenzoboroxole-functionalized magnetic nanoparticles (MNPs) were prepared to achieve efficient capture of cis-diol-containing flavonoids under neutral conditions. Branched PEI was applied as a scaffold to amplify the number of boronic acid moieties, while 3-carboxybenzoboroxole, exhibiting high affinity and excellent water solubility toward flavonoids, was used as an affinity ligand. The prepared boronate affinity MNPs exhibited high binding capacity and fast binding kinetics (equilibrium in 3 min) under neutral conditions. In addition, the obtained boronate affinity MNPs exhibited high binding affinity (K d ≈ 10-4 M), low binding pH (pH ≥ 6.0) and tolerance of the interference to abundant sugars.

Efficient vitamin B12-imprinted boronate affinity magnetic nanoparticles for the specific capture of vitamin B12.

Vitamin B12 (VB12) has an important function in human physiology. However, analysis of VB12 at natural levels in foods or biological samples is difficult because of its very low concentration level and the presence of high-abundance components which can interfere with the measuring system. Thus, it is essential to develop efficient and selective enrichment approaches for VB12. Molecularly imprinted polymers (MIPs) have important applications from separation and sensing to catalysis. However, there is no report on the preparation of MIPs for VB12. Here, we use boronate affinity-based oriented surface imprinting to prepare MIPs for VB12. A VB12 template was first covalently immobilized onto the surface of boronic acid functionalized magnetic nanoparticles. Subsequently, a thin imprinting coating of poly(2-anilinoethanol) was formed to cover the substrate surface via in-water polymerization. After removing the template, 3D cavities complementary to the molecular size and shape of the template were formed in the imprinting layer. The imprinting coating was highly hydrophilic and presented limited residual boronic acid, thus non-specific binding was avoided. The prepared MIPs exhibited several highly favorable features, including excellent specificity, high binding strength and low binding pH. The prepared MIPs were successfully applied to the analysis of VB12 in human milk.

[A preliminary study on the measurement of (1,3)-ß-D-glucan in bronchoalveolar lavage for the diagnosis of pulmonary fungal infections].

OBJECTIVE: To explore the measurement of (1,3)-ß-D-glucan bronchoalveolar lavage fluid (BALF) for the diagnosis of pulmonary fungal infections. METHODS: A total of 135 patients in the General Hospital of Tianjin Medical University from February 2010 to February 2011 were enrolled. There were 34 cases of confirmed or clinically diagnosed pulmonary fungal infections, 53 cases of bacterial pneumonia, and 48 cases of non-infection diseases. All patients underwent BAL and the BALF samples were obtained. (1,3)-ß-D-glucan content (G test), in BALF and plasma were tested and the data were analyzed statistically by Mann-Whitney while the receiver operating characteristic curve (ROC curve) was established, from which the best threshold of the 2 G tests was derived. RESULTS: The median of BALF G test in the fungal infection group, pneumonia group and non-infection group was 281, 28 and 10 ng/L, respectively; the level in the fungal infection group being significantly higher than those of the other 2 groups (P < 0.001), but no significant difference being observed between the pneumonia group and the non-infection group (P > 0.05). The median of plasma G tests in the fungal infection group, the pneumonia group and the non-infection group was 27, 10, and 5 ng/L, respectively; the level in the fungal infection group being significantly higher than those in the other 2 groups (P < 0.001), but there was no significant difference between the pneumonia group and the non-infection group (P > 0.05). The best threshold of BALF G test was 67 ng/L, while the best threshold of G test of plasma was 17 ng/L. CONCLUSION: As compared to G test of plasma, G test of BALF may be more accurate, and have a higher clinical value for the earlier diagnosis of pulmonary fungal infections.

[Cloning and expression of N-acetyl-D-neuraminic acid aldolase in Escherichia coli].

OBJECTIVE: To obtain the Escherichia coli strains expressing N-Acetyl-D-neuraminic acid aldolase (Neu5Ac aldolase). METHODS: The gene (nanA) coding Neu5Ac aldolase was cloned from Escherichia coli C600, and the recombinant plasmid was sequenced and expressed in Escherichia coli. RESULTS: Sequencing data revealed that the open reading frame was 894 bp and predicted to encode a protein consisting of 298 amino acids. The patterns of SDS-PAGE showed that the purified enzyme protein as a single protein band with a molecular weight of 33 kD, which was consistent with those reported in the reference. In the recombinant plasmid pRY1, the expression of nanA gene was controlled by the lac promoter with the induction of IPTG or lactose. The plasmid pRY3 was constructed, in which the nanA gene ws controlled by the tac promoter. The protein of Neu5Ac aldolase was constitutively expressed using the recombinant strain, E.coli DH5 alpha/pRY3 without induction of IPTG or lactose. The crystal was finally obtained with the efficiency of 90.2% of Neu5Ac. The HPLC indicated that the Neu5Ac crystal prepared in this experiment was same as Simga product. CONCLUSION: The protein products expressed by two recombinant strains E.coli BL21(DE3)/pRY1 and DH5 alpha/pRY3 has the characteristics of Neu5Ac.