A novel electrochemical immunosensor for highly sensitive detection of aflatoxin B1 in corn using single-walled carbon nanotubes/chitosan.

A sensitive electrochemical immunosensor for aflatoxin B1 (AFB1) detection based on single-walled carbon nanotubes/chitosan was presented. The immunosensor was based on an indirect competitive binding to a fixed amount of anti-AFB1 between free AFB1 and AFB1-bovine serum albumin, which conjugate immobilized on covalently functionalized nanotubes/chitosan laid on the glass carbon electrode. Then, the anti-mouse immunoglobulin G secondary antibody labeled with alkaline phosphatase was bound to the electrode surface through reacting with primary antibody. Finally, alkaline phosphatase catalyzes the hydrolysis of the substrate α-naphthyl phosphate, which produced electrochemical signal. Compared with conventional methods, the established immunosensor was more sensitive and simple. Under optimal conditions, this method could quantitatively detect AFB1 from 0.01 to 100 ng mL(-1) with a detection limit of 3.5 pg mL(-1). Moreover, the immunosensor was successfully applied to assay AFB1 in corn powder, which showed good correlation with the results obtained from high performance liquid chromatography.

[Transcranial surgical correction of cranio-orbital fibrous dysplasia with lateral orbital approach].

OBJECTIVE: To explore the transcranial surgical method with lateral orbital approach for the treatment of cranio-orbital fibrous dysplasia. METHODS: Lateral orbital transcranial extradural approach was adopted to correct complicated fibrous dysplasia in which the frontal, orbital, sphenoid, temporal bones were involved. Partial lesion removal and optic nerve decompression were performed through the transcranial extradural route by fronto-temporal cranial bone flap exposure. The fronto-orbital skeleton was shaped after bone flap deactivation. RESULTS: 8 cases were treated successfully with no complication. The period of follow-up ranged from 9 months to 3 years. The appearance and the vision improved greatly. Cranial CT showed good bony union with no relapse. CONCLUSIONS: Lateral orbital transcranial surgical approach is an optimal technique to correct cranio-orbital fibrous dysplasia.

[Construction and functional identification of eukaryotic expression vector carrying Sprague-Dawley rat MSX-2 gene].

OBJECTIVE: To construct a high effective eukaryotic expressing plasmid PcDNA 3.1-MSX-2 encoding Sprague-Dawley rat MSX-2 gene for the further study of MSX-2 gene function. METHODS: The full length SD rat MSX-2 gene was amplified by PCR, and the full length DNA was inserted in the PMD1 8-T vector. It was isolated by restriction enzyme digest with BamHI and Xhol, then ligated into the cloning site of the PcDNA3.1 expression plasmid. The positive recombinant was identified by PCR analysis, restriction endonudease analysis and sequence analysis. Expression of RNA and protein was detected by RT-PCR and Western blot analysis in PcDNA3.1-MSX-2 transfected HEK293 cells. RESULTS: Sequence analysis and restriction endonudease analysis of PcDNA3.1-MSX-2 demonstrated that the position and size of MSX-2 cDNA insertion were consistent with the design. RT-PCR and Western blot analysis showed specific expression of mRNA and protein of MSX-2 in the transfected HEK293 cells. CONCLUSIONS: The high effective eukaryotic expression plasmid PcDNA3.1-MSX-2 encoding Sprague-Dawley Rat MSX-2 gene which is related to craniofacial development can be successfully reconstructed. It may serve as the basis for the further study of MSX-2 gene function.