Study On The Apoptosis Of The Tumor Cells Induced By Gold Nanoparticle Near-infrared Hyperthermia

Malignant tumor is one of the most serious diseases which is harmful to human health.Around the world,about 700 million people each year were killed due to the tumor.Recently,the incidence is still increasing,the number of the death is about 150 million,which is exceed cardiovascular and cerebrovascular diseases become the main cause of death.Currently,the methods of used clinically cancer treatment include surge, chemotherapy and radiotherapy.Surgical treatment have restriction of tumor resect,not all tumor can be surgery.The biggest drawback of chemotherapy and radiotherapy is that they damage normal tissues and cells when they destroy the tumor cells besides drug resistance,especially in hematopoietic tissues and cells.Hyperthermia is a method of use heat to kill tumor,that is use the physical energy precipitated in the organization,so that thermal effects arising from the tumor tissue temperature can reach the effective treatment temperature,and last for some time can kill the cancerous cells without damage the normal cells.Hyperthermia is a physical therapy because it has less side effects than chemotherapy and radiothera significantly. Over the past 20 years,hyperthermia developed rapidly,and has shown a good clinical results.Recently,it is recognized as a treatment for tumors of the "green therapy".Ultrasound,microwave thermotherapy,radiofrequency hyperthermia therapy has a rapid development.In recent years,with the development of nanotechnology,gold nanopaticle has aroused widespread interest of people.Gold nanoparticle has a strong optical absorption in the near infrared region.Near infrared region(800-1200 nm) is the transmission window of the body,the injury of near-infrared laser to the human body is much smaller compared to other band laser.If gold nanoparticle irradiated by the near-infrared laser,the gold nanoparticle will conver the absorbed light energy into heat,the tumor cells will been killed because of the enhanced temperature of the tumor.Conjunction with the anti-cancer drugs hyperthermia can improve the efficacy.This technology can be avoided the shortcomings of surgical treatment,radiotherapy and chemotherapy.Infraed hyperthermia will have a wide range of applications in the biomedical field.In this study,we synthesis gold nanoshell and gold nanorod,detect the inhibiton of the near infrared hyperthermia to the tumor cell and study the mechanism of infrared hyperthermia.1 We synthesis gold nanoshell and gold nanorod with the wet chemical method and seed growth method respectively.Gold nanoshell has a diamerter of 20nm,thickness of 5nm;gold nanorod has a length of 45 nm,width 10nm.These two materials has a good characteristics of near-infrared absorption.2 The cell toxicity of gold nanoshell and gold nanorod to liver cancer cells HepG2 and breast cancer cells MCF-7 were detected by MTT method.The results showed that the non-toxic concentration of gold nanoshell is 25%and the concentration of gold nanorod is 20%.3 After infrared hyperthermia,the cell proliferation of liver cancer cells HepG2 and breast cancer cells MCF-7 were inhibited.The inhibited rate was increased with the increase of the irradiated power.The largest inhibitory rate is up to 90%.The microscope observation and fluorescence staining showed that tumor cells after hyperthermia became round,smaller,and the number of off-walled cell also increased and nuclear staining is enhanced,the cells showed apoptotic features.4 To illuminate the mechanism of cell death induced by infrared hyperthermia,we detect the change of apoptotic gene by RT-PCR and Real-time PCR and the activity of Caspase-3 protein.After infrared hyperthermia,the mRNA expression level of p53 and bax increased obviously,the mRNA expression level of bcl-2 decreased,the vitality of Caspase-3 protein also has a marked increase.This shows that apoptosis induced by infrared hyperthermia is executed by mitochondrion pathway,hsp70 expression in the course of therapy was significantly up-regulated.In all stages of apoptosis plays a role in anti-apoptosis.At the same time,the body's immune system will also enhance, hsp70 will effct the expression of Bax,bcl-2 and p53 The effect of killing tumor cells increased,and also to play a role in apoptosis.In summary,we synthesis gold nanoshell and gold nanorod.They have good characteristics of near-infrared absorption.Cell toxicity results display they have good biocompatibility.And cell growth inhibition were measured,results showed that the infrared hyperthermia can inhibit tumor cell growth,the largest inhibitory rate is up to 90%.And further study the mechanism of apoptosis of infrared hyperthermia.In addition,gold nanoparticle can been modified easily through the surface molecules to increase their intake of cells and enhanced targeted effect to the tumor. Therefore,this study may provide a new way of solid tumors and other tumor targeted therapy.This study provide a new idea for the futher study of the preparation of nanomaterials,the selection of nanoparticles surface-modified material,the nanomaterials residue after treatment and the effect to the normal tissues.It will become a efficient method to treat tumor.