The synergistic effect of photodynamic therapy and photothermal therapy in the presence of gold-gold sulfide nanoshells conjugated Indocyanine green on HeLa cells.

BACKGROUND: Photodynamic therapy (PDT) and photothermal therapy (PTT) are two known optical remedies of cancer. PTT can be combined with other therapies. One of the limitations of optical therapies is the penetration of light into biological tissues, which reduces its effectiveness due to usage of photosensitizers and PTT agents, which are absorbed in the NIR region that provides the maximum penetration. For instance, Indocyanine green (ICG) serves as a photosensitizer and Gold nanostructures as agents for PTT. GGS is a gold nanoshell with two absorption peaks in the NIR and visible regions. The aim of this study is to evaluate the synergistic effect of PDT and PTT in the presence of GGS conjugated with ICG. METHODS: After synthesizing GGS, ICG was conjugated with GGS. The specifications and cytotoxicity of agents were identified. Cells were irradiated by an 808nm laser with or without the agents and three laser outputs were achieved, with each having four different exposure times. The viability of treated cells was determined via MTT assay. RESULT: The irradiation of the laser did not produce any significant effect by itself or in the presence of GGS. The maximum cell death recorded for GGS, ICG and GGS-ICG were 15±7%, 50±3% and 31±3% respectively. ICG and GGS-ICG differs significantly for exposures higher than 2250J/cm2. CONCLUSION: The conjugate was provided through a simple process and a greater chemical stability compared to GGS was achieved. Moreover, it induced a stronger photodynamic and photothermal effect on the cells. This is a promising result which can help enhance the effectiveness of a minimally invasive treatment.

Silver nanoparticles increase cytotoxicity induced by intermediate frequency low voltages.

Electrical properties of the cells play a key role in biological processes. Intermediate frequencies of electrical fields influence the cells proliferation without heat generation and electrical stimulation. Silver nanoparticle (SNP) as a metallic agent can change the electrical characteristics of the cells. We study the effect of low voltages at an intermediate frequency (300 kHz) on a human breast adenocarcinoma cell line (MCF7) in the presence of SNPs. At first, cell toxicity of SNPs was determined at different concentrations. Then three different voltages were applied to the cells for 15 min, both in the presence and absence of SNPs. The treatments efficiency was evaluated by MTT assay. The results showed that the intermediate frequency-low voltages with SNPs not only provide an additive efficacy on cytotoxicity, but also a synergism was observed between these factors. By increasing the voltage from 3 to 9 V, a rising synergistic rate was observed. It seems that the synergistic effect between SNPs and the 300 kHz low voltages can inhibit cell proliferation and/or increases cell death of MCF-7, and hence increases treatment efficiency of SNPs, effectively.

Sonodynamic Therapy Using Protoporphyrin IX Conjugated to Gold Nanoparticles: An In Vivo Study on a Colon Tumor Model.

OBJECTIVES: Sonodynamic therapy is a physical treatment which utilizes ultrasound waves with an appropriate sensitizer such as protoporphyrin IX (PpIX). The activation of sensitizer depends on cavitation, and therefore, high intensity ultrasound is an important necessity. Beside, high intensity ultrasound can induce side effects on the healthy tissues which have surrounded tumor. The particles in a liquid decrease the ultrasonic intensity threshold needed for onset of cavitation. The non-radiative relaxation time of PpIX in the presence of gold nanoparticles (GNP) is longer than the similar time without GNP. MATERIALS AND METHODS: This study was conducted on colon carcinoma tumor in BALB/c mice. The tumors were induced by subcutaneous injection of CT26 cells. Ultrasound irradiation were performed on tumors 24 hr after the injection of PpIX into GNPs. Antitumor effects were estimated by measuring tumor relative volume, doubling time and time being five times of the tumors and by calculating the average survival time of tumor-bearing mice after treatment. RESULTS: There is no inhibitory effect in control group. Ultrasound irradiation alone showed a slight antitumor effect which was enhanced by ultrasound plus PpIX (SDT). The synergistic inhibitory effect was significant when ultrasound plus PpIX was conjugated to GNPs. CONCLUSION: Our experiments suggested a significant synergistic effect of ultrasound combined with Au-PpIX that reduced tumor relative volume and increased average animal survival fraction. This effect was obviously stronger than ultrasound alone and synergistic effect of ultrasound combined with PpIX.