title: Laser heating of gold nanospheres functionalized with octreotide: in vitro effect on HeLa cell viability.
abstract: OBJECTIVE
  The aim of this study was to assess the effect of laser heating a well-characterized gold nanoparticle (AuNP)-octreotide system on HeLa cell viability, to evaluate its potential as a suitable agent for plasmonic photothermal therapy.
  
  
  BACKGROUND
  Octreotide is a synthetic peptide derivative of somatostatin with an effect on the survival of HeLa cells. Peptides bound to AuNPs are biocompatible and stable multimeric systems with target-specific molecular recognition.
  
  
  METHODS
  Octreotide was conjugated to AuNPs (∼20 nm) by spontaneous reaction with the thiol groups. The nanoconjugate was characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), ultraviolet visible spectroscopy (UV-Vis), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. Irradiation experiments were conducted using an Nd:YAG laser pulsed for 5 ns at 532 nm with a repetition rate of 10 Hz for up to 6 min while delivering an average irradiance of 0.65 W/cm(2). HeLa cells were incubated at 37°C (1) with AuNP-citrate, (2) with AuNP-octreotide, or (3) without nanoparticles.
  
  
  RESULTS
  After laser irradiation, the presence of AuNP caused a significant increase in the temperature of the medium (48°C vs. 38.3°C of that without AuNP). The AuNP-octreotide system resulted in a significant decrease in cell viability of up to 6 % compared with the AuNP-citrate system (15.8±2.1%). Two possible mechanisms could be at play: (1) octreotide alone exerts an effect on survival HeLa cells, or (2) the release of heat (∼727°C per nanoparticle) in the membranes or cytoplasm of the cells caused by the interaction between AuNP-octreotide and somatostatin receptors reduced viability.
  
  
  CONCLUSIONS
  The AuNP-octreotide system exhibited properties suitable for plasmonic photothermal therapy in the treatment of cervical cancer.
authors.affiliation: Instituto Nacional de Investigaciones Nucleares, Estado de México, Mexico.
authors.forename: Héctor
authors.initials: H
authors.lastname: Mendoza-Nava
authors.forename: Guillermina
authors.initials: G
authors.lastname: Ferro-Flores
authors.forename: Blanca
authors.initials: B
authors.lastname: Ocampo-García
authors.forename: Jorge
authors.initials: J
authors.lastname: Serment-Guerrero
authors.forename: Clara
authors.initials: C
authors.lastname: Santos-Cuevas
authors.forename: Nallely
authors.initials: N
authors.lastname: Jiménez-Mancilla
authors.forename: Myrna
authors.initials: M
authors.lastname: Luna-Gutiérrez
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Camacho-López
mesh_terms: D018931:Antineoplastic Agents, Hormonal / Q000008:administration & dosage*; D002470:Cell Survival / Q000187:drug effects; D006046:Gold / Q000737:chemistry*; D006367:HeLa Cells; D006801:Humans; D053844:Lasers, Solid-State; D053768:Metal Nanoparticles / Q000737:chemistry*; D046529:Microscopy, Electron, Transmission; D015282:Octreotide / Q000008:administration & dosage*; D013057:Spectrum Analysis
chemical_list: D018931:Antineoplastic Agents, Hormonal; D006046:Gold; D015282:Octreotide