title: Experimental study on in vitro tumor cell killing by focused bi-frequency ultrasound activated hematoporphyrin derivatives.
abstract: OBJECTIVE
  As ultrasound has become an important therapeutic technique on tumor, in order to find the cell-killing effect of focused bi-frequency ultrasound activated hematoporphyrin derivatives, experimental study was processed in vitro.
  
  
  METHODS
  Tumor cells K562 and SW-480 were killed by focused bi-frequency ultrasound activated hematoporphyrin (Hp) derivatives under optimized ultrasonic parameters and the cell-killing effect was tested by MTT (Thiazolyl blue: 3-(4,5-Dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide) technique.
  
  
  RESULTS
  The lower frequency (0.6 MHz) was better than the higher (1.1 MHz) in activating hematoporphyrin derivatives; the bi-frequency was better than mono-frequency, and the cell-killing efficiency was 2-3 times of sum of the two kinds of ultrasounds which constitute bi-frequency. Incubation for the 16 h was better than 4 h after the cells exposed to the ultrasound.
  
  
  CONCLUSIONS
  The method of killing tumor cells by focused bi-frequency ultrasound activated hematoporphyrin derivatives is presented and evaluated in this paper.
authors.affiliation: Biomedical Engineering Center, Beijing University of Technology, Beijing, China.
authors.forename: Z
authors.initials: Z
authors.lastname: Shang
authors.forename: X
authors.initials: X
authors.lastname: Ren
authors.forename: J
authors.initials: J
authors.lastname: Zhang
authors.forename: X
authors.initials: X
authors.lastname: Zhu
authors.forename: H
authors.initials: H
authors.lastname: Qi
authors.forename: Q
authors.initials: Q
authors.lastname: Liu
authors.forename: K
authors.initials: K
authors.lastname: Zhang
authors.forename: S
authors.initials: S
authors.lastname: Wu
authors.forename: Y
authors.initials: Y
authors.lastname: Zeng
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D045744:Cell Line, Tumor; D003110:Colonic Neoplasms / Q000188:drug therapy* / Q000473:pathology*; D006415:Hematoporphyrins / Q000627:therapeutic use*; D006801:Humans; D020014:K562 Cells; D017319:Photosensitizing Agents / Q000627:therapeutic use; D016896:Treatment Outcome; D014464:Ultrasonic Therapy / Q000379:methods*
chemical_list: D006415:Hematoporphyrins; D017319:Photosensitizing Agents