Study On Remote Implant For Upconversion Photodynamic Therapy

Conventional cancer treatment includes chemotherapy,radiotherapy,and surgery.Note that chemotherapy is often associated with systemic side-effects,high recurrence rate is associated with surgical resection of tumors,while radiation therapy is limited by cumulative radiation dose.Photodynamic therapy(PDT)is an alternative tumor-ablative and function-sparing oncologic intervention.Essentially,it involves the administration of a tumor-localizing photosensitizer(PS)followed by local illumination with specificwavelength light.The excited PS then transfers its energy to molecular oxygen,and generates cytotoxic reactive oxygen species,such as singlet oxygen that can oxidize key cellular macromolecules leading to tumor cell ablation.Recently,upconversion nanoparticles(UCNPs)are found very useful to enhance PDT especially for the treatment of solid and large tumors.In other words,UCNPs could act both as PS delivery agent and the converter from near infrared(NIR)light to visible light.Therefore,UCNPsare of great helps to activate PS at much deeper-level tissues.However,it is still not able to deal with deep tissues and large lesions outside the NIR window.This paper attempts to design a remote-controlled implant system for photodynamic therapy,which is comprised of the in vivo implant and the in vitro controller.The implant should be deployed near the lesion by minimally invasive surgery.It is excitable by a laser light source required for up-conversion photodynamic therapy.In general,the microscale light source consists of a light-emitting module,a wireless communication module,and a controlling module.The in vitro controller administrates the operating states of the in vivo implant by means of wireless communication.In order to evaluate the functionality and reliability of this remote-controlled implant system for photodynamic therapy,we established a set of experimental simulation apparatuses.It is thus able to quantify the linear relationship between the intensity of fluorescence and the concentration of UCNs in a closed environment.The results confirm the effectiveness and reliability of the remote-controlled implant system for photodynamic therapy.