title: [A colorimetric method for vascular endothelial growth factor detection based on aptamer and magnetic beads].
abstract: OBJECTIVE
  To develop a novel colorimetric method for detecting the tumor biomarker vascular endothelial growth factor (VEGF) based on aptamer and magnetic beads.
  
  
  METHODS
  The capture aptamer was hybridized to urease functionalized single-stranded DNA (ssDNA) and immobilize on the surface of magnetic beads by specific biotin-avidin binding. In the presence of VEGF, aptamers bound to VEGF to form a specific stem-loop structure to release the urease functionalized ssDNA. After separation, the supernatant was transferred to a tube and urea and phenol red were added. Urease hydrolyzed urea to produce ammonia to cause an increase of the pH value and a color change of phenol red. The results were inspected with either the naked eyes or by a UV spectrophotometer.
  
  
  RESULTS
  Under optimized conditions, the detection system showed a good linear relationship for VEGF detection in the range of 0.1 to 10 pmol/L with a detection limit as low as 0.06 pmol/L. The results of VEGF detection in the serum of patients with lung cancer were consistent with those using an ELISA Kit. The results of examination of 10 serum samples with this aptamer-based method and ELISA kit showed that the accuracy of this method was 90%.
  
  
  CONCLUSIONS
  This aptamer-based system provides an simple and convenient method for VEGF detection with a high sensitivity and selectivity.
authors.affiliation: Department of Oncology with Integrated Traditional Chinese and Western Medicine, First Hospital of Fuzhou, Fuzhou 350009, China. E-mail: ljr166@hotmail.com.
authors.forename: Jing-Rong
authors.initials: JR
authors.lastname: Liu
authors.forename: Yun-Ling
authors.initials: YL
authors.lastname: Pan
authors.forename: Yan-Ping
authors.initials: YP
authors.lastname: Zhao
authors.forename: Mei-Cen
authors.initials: MC
authors.lastname: Liu
authors.forename: Jing-Hua
authors.initials: JH
authors.lastname: Chen
authors.forename: Chun-Yan
authors.initials: CY
authors.lastname: Li
mesh_terms: D052157:Aptamers, Nucleotide; D014408:Biomarkers, Tumor; D003124:Colorimetry; D004277:DNA, Single-Stranded; D006801:Humans; D008175:Lung Neoplasms; D009693:Nucleic Acid Hybridization; D042461:Vascular Endothelial Growth Factor A / Q000032:analysis*
chemical_list: D052157:Aptamers, Nucleotide; D014408:Biomarkers, Tumor; D004277:DNA, Single-Stranded; D042461:Vascular Endothelial Growth Factor A