title: Enhanced photoacoustic detection of melanoma cells using gold nanoparticles.
abstract: OBJECTIVE
  We tagged melanoma cells with gold nanoparticles to show their viability for increasing sensitivity in a photoacoustic detection system. Ultimately, this study models the detection of circulating tumor cells, which are an important prognostic factor in the progress of melanoma.
  
  
  METHODS
  A Q-switched, tunable Nd:YAG laser was used to irradiate cells in both a stationary and flow set-up. Photoacoustic signals were measured using a polyvinylidene fluoride (PVDF) film in the stationary test, and a commercially available ultrasonic probe for flow tests. Both unmodified melanoma cells and gold nanoparticle (AuNP) tagged melanoma were tested.
  
  
  RESULTS
  AuNP tagged melanoma in a stationary set-up showed an average of 0.227 mV/mJ larger signal than the untagged, indicating a signal increase of 34%. At 500 nm there is a maximum difference of 0.295 mV/mJ, or a 41% increase. In flow tests, the ultrasound probe was able to detect single cells, but the increased signal from AuNP tagging was minimal.
  
  
  CONCLUSIONS
  AuNP tagging proved to give an increased photoacoustic signal allowing greater sensitivity in stationary metastasized melanoma detection systems using photoacoustics.
authors.affiliation: Department of Biological Engineering, University of Missouri, Columbia, Missouri, USA.
authors.forename: Devin R
authors.initials: DR
authors.lastname: McCormack
authors.forename: Kiran
authors.initials: K
authors.lastname: Bhattacharyya
authors.forename: Raghuraman
authors.initials: R
authors.lastname: Kannan
authors.forename: Kattesh
authors.initials: K
authors.lastname: Katti
authors.forename: John A
authors.initials: JA
authors.lastname: Viator
mesh_terms: D000162:Acoustics / Q000295:instrumentation*; D014408:Biomarkers, Tumor / Q000032:analysis*; D045744:Cell Line, Tumor; D002469:Cell Separation / Q000379:methods; D005434:Flow Cytometry / Q000379:methods; D006046:Gold / Q000032:analysis*; D006801:Humans; D054023:Lasers, Semiconductor; D008545:Melanoma / Q000737:chemistry* / Q000473:pathology; D053768:Metal Nanoparticles / Q000032:analysis*; D015336:Molecular Probe Techniques; D009360:Neoplastic Cells, Circulating / Q000737:chemistry* / Q000473:pathology; D010363:Pattern Recognition, Automated; D012878:Skin Neoplasms / Q000737:chemistry* / Q000473:pathology
chemical_list: D014408:Biomarkers, Tumor; D006046:Gold