Surface Charge Modification Of Gold Nanorods And The Application Of Calcium Carbonate-coated Gold Nanorods In Anti-tumor Applications

Cancer has posed a great threat to human health.In recent years the number of cancer deaths in the world has been rising.Human beings have never ceased to fight the tumor.At present,the clinical methods based on surgical resection,chemical therapy and radiation therapy.Surgical resection is better for early treatment of tumors,but the proportion of postoperative complications is still high.Both chemotherapy and radiation therapy can be a great burden on patients’ physical and mental.Therefore,the high efficacy,low toxicity and stability of the anti-tumor method is an urgent expectation.Photothermal therapy and ultrasound therapy as two new anti-cancer therapies in recent years,can kill the tumor tissue.At the same time,small wound surface,low side effects,is currently the main direction of the research.As we know,gold nanorods as a metal nano-materials has a wide range of applications in sensors,optical components and biomedical field.Gold nanorods have good biocompatibility,low toxicity and quite stable physical and chemical properties.More importantly,the gold nanorods have extremely high photothermal conversion efficiency and unique light-absorbing properties which can be applied to photothermal therapy and photoacoustic imaging.Calcium carbonate as a common calcium supplements is one of the main ingredients of calcium tablets.Nano-scale calcium carbonate will produce carbon dioxide bubbles under weakly acidic,combined with the cavitation of ultrasound,bubbles will be transformed into anti-tumor "nano bomb".At present,people have made gratifying progress in these two areas of treatment,but there are still many problems to be solved.Therefore,we designed a calcium carbonate coated gold nanorods,make full use of gold nanorods of the photothermal performance and photoacoustic signal changes,relying on ultrasonic cavitation to assist in anti-tumor therapy.In this paper,combining with the actual situation,the use of gold nanorods as the carrier,by modifying the polyethyleneimine and polyethylene glycol instead of gold nanorodsurface CTAB,relying on electrostatic adsorption to form the calcium carbonate shell,forming a multifunctional joint diagnosis and treatment system with photothermal therapy,ultrasonic therapy,and acoustic positioning.The physical and chemical properties of the materials were characterized by transmission electron microscopy,potential particle size analysis,UV absorption spectroscopy and inductively coupled plasma spectroscopy.The anti-tumor effect of the material at the cellular level was studied by cytotoxicity test,in vitro and in vivo photothermal experiments,ultrasonic experiments and photoacoustic imaging.The results show that the system has a better effect of photothermal treatment and combined treatment,but also to achieve the photoacoustic localization of the tumor.It is hoped that through the research of this paper,it will provide some reference for the research and application of photothermal therapy and ultrasonic therapy,and provide the power for the development of anti-tumor.