Li Zhou research group, Beijing Institute of nano energy and systems, Chinese Academy of Sciences: the precision drug delivery system controlled by the implanted friction nano generator with magnetic mutually exclusive structure to achieve efficient tumor treatment

Introduction friction Nanogenerator (Teng) is a device based on coupling friction electrification and electrostatic induction proposed by Academician Wang Zhonglin in 2012 It can convert mechanical energy in the environment into electrical energy, with the characteristics of high voltage and low current Teng has been widely used in biomedical fields such as nervous system, circulatory system, cell regulation, sterilization and degradable electronic devices, which is of great significance to the development of wearable and implantable electronic medical fields Recently, Li Zhou research group of Beijing Institute of nano energy and systems, Chinese Academy of Sciences, has completed the development of an implantable friction nano generator (mteng) with magnetic mutual exclusion structure for the first time The same level repulsion force of magnet enables the mteng to maintain long-term and stable power output after encapsulation and implantation The team combined mteng with interdigital electrode or micropipette electrode to make the output electric field have precise control on the release of adriamycin loaded erythrocyte membrane Furthermore, the research group cooperated with Wei Wei, a researcher of the Institute of process engineering, Chinese Academy of Sciences, and achieved excellent tumor treatment effect under the premise of low dose in three levels of two-dimensional tumor cells, three-dimensional tumor spheres and solid tumors in mice Relevant research results were published in the latest issue of advanced functional materials (DOI: 10.1002 / ADFM 201808640), a famous international academic journal, under the title of "highly efficient in vivo cancer therapy by an implantable magnet triboelectric Nanogenerator" Figure 1 High performance and stable output implantable magnet Nanogenerator to control drug delivery Magnet Nanogenerator can precisely control the release of anticancer drugs in red blood cells at tumor sites, so as to achieve excellent antitumor efficiency in vivo (source: adv funct Mater.) introduction to researcher Li Zhou, researcher of Beijing nano energy and System Research Institute, doctoral supervisor, national ten thousand talents plan "youth top" (2017) He received a bachelor's degree in medicine from Wuhan University and a doctor's degree from Peking University He studied at Georgia University of technology in the United States At present, he is vice chairman of Youth Committee of Chinese society of Biomedical Engineering, director of biology and environment platform of Beijing Institute of nano energy and system, Chinese Academy of Sciences, and project leader It has been selected as "outstanding talents in the new century" (2012) of the Ministry of education, "new star of science and technology" (2012), and "top young talents of high innovation program" (2015) Mainly engaged in the research of implantable and wearable electronic medical devices, biosensors and degradable medical devices More than 60 SCI papers have been published, among which 3 papers have been published in the sub journals of science and nature, and 26 papers have been published as the first author or corresponding author in the top international academic journals with an impact factor of more than 10, with more than 2500 citations In 2017, he won the second prize of science and technology of Beijing (provincial and ministerial level, the first adult), the Young Scientist Award of International Federation of medicine and Bioengineering (IFMBE), the gold award of China Invention Association (ranking first) and the first prize of the youth thesis competition of Biomedical Engineering Conference Cutting edge scientific research achievements: the precision drug delivery system controlled by the magnetic mutually exclusive structure implanted friction nano generator realizes efficient cancer treatment With the development of science and technology industry and the advent of an aging society, cancer has become one of the high-risk diseases that seriously threaten human health According to statistics, in 2018, there are about 18 million cancer patients in the world, and the number of cancer patients is increasing every year At present, chemotherapy is the most widely used cancer treatment, but there are still many problems, including serious side effects and low therapeutic effect For example, adriamycin, a star drug in chemotherapy, often causes a series of side effects, including heart poisoning, inhibition of bone marrow growth, mucositis and baldness Therefore, drug delivery system with targeted tumor sites has become a hot research topic in recent years The most ideal goal is to establish a drug delivery system that can deliver the chemotherapy drugs to the focus, so as to improve the killing efficiency of tumor cells and reduce the occurrence of side effects; furthermore, if the controlled release of drugs in the tumor site can be achieved, it will be a more superior treatment method The drug delivery system based on cell vesicles has unique advantages Among them, red blood cells have many advantages, such as long as 120 days of internal circulation time, good stability and scalability, no immunogenicity of external grafts and so on It is a good tumor drug delivery carrier At the same time, the drug loaded red blood cells can release in response to the stimulation of high voltage electric field However, the traditional high-voltage power supply equipment is bulky, low safety factor, patients can not operate independently, these factors hinder the application of electric field controlled drug delivery system in cancer treatment Therefore, it is urgent to develop a new drug delivery system with high safety, good specificity, significant efficacy and controlled release In this study, the author first prepared a small-scale implantable friction nano generator (mteng) with magnetic mutual exclusion structure The circular mteng can effectively avoid the stimulation of sharp parts such as corners on the implanted parts (Fig 2a, b) The main working principle of mteng is that the surface of polytetrafluoroethylene and titanium sheet generates equal amount of heterogeneous charge during contact friction, and the potential difference generated after separation drives electrons to flow in the external circuit to generate current (Fig 2c, d) The biggest advantage of mteng is that its electrical performance remains stable after encapsulation and implantation Mteng with a diameter of 2.5 cm can generate electrical output of up to 70 V, 550 Na and 25 NC after encapsulation and implantation (Fig 2F, g) Figure 2 The structure and output performance of mteng (source: adv funct Mater.) next, the author loaded adriamycin into RBC membrane extracted from Kunming mice by hypoosmotic dialysis Through confocal microscopy and flow cytometry, we found that the drug loaded RBC membrane system with good structure and loading rate of up to 90% (Fig 3A) After 7 days, the cell membrane was still intact, and up to 70% of doxorubicin remained in the membrane Furthermore, the author combines mteng with interdigital electrode, and the bottom electric field intensity is as high as 4 kV / cm according to COMSOL fitting (Fig 3b) As shown in Figure 3C, about 40.3% adriamycin was released from the erythrocyte membrane after 1 h of electric field stimulation by mteng, and the release amount reached 59.7% after 8 h In contrast, only 14.4% of adriamycin was released from the erythrocyte membrane in the control group without electric field stimulation Then, in the next experiment, the author first used the electric field generated by mteng to stimulate for 10 min, and observed the release of adriamycin which was three times higher than the background value After the electric field disappeared, the release amount quickly returned to the background value, which verified that the release of adriamycin would accelerate only when the electric field existed (Fig 3D, e) Through scanning electron microscopy, the author observed that the original red blood cells and adriamycin loaded red blood cell membranes maintained two concave and round cake like structures, while nano pores were observed on the red blood cell membranes stimulated by electric field, and the nano pores disappeared after the electric field disappeared (Fig 3f-i) Thus, the drug release system controlled by mteng was obtained (Fig 3j) Figure 3 Mteng controlled drug loaded erythrocyte membrane release system (source: adv funct Mater.) next, the authors used the same device to verify the feasibility of application at the two-dimensional HeLa tumor cell level Firstly, HeLa cells grew on the wall overnight When the drug loaded erythrocytes settled to the same plane as HeLa cells (FIG 4A), the author stimulated them with the electric field generated by mteng for 1h, and then cultured HeLa cells and drug loaded erythrocytes for 24h The killing ability of tumor cells was measured by CCK-8 experiment (Fig 4b, c) The activity of HeLa cells could not be affected by electric field, drug-free erythrocytes and the simultaneous action of electric field and drug-free erythrocytes 0.1 μ g / ml free adriamycin reduced the cell activity to 70.4%, and the electric field effect of mteng slightly increased the cytotoxicity of adriamycin to 62.7% Using the same content of adriamycin loaded erythrocytes, the activity of erythrocytes was reduced to 40.9%, which was more effective than adriamycin alone More importantly, the activity of HeLa cells stimulated by mteng decreased rapidly to 20.9%, and the same conclusion was obtained from the staining experiment of living and dead cells (Fig 4d-k) The above data prove the feasibility and rationality of mteng controlled drug delivery system in two-dimensional cell level Figure 4 The application of mteng controlled drug delivery system on 2D HeLa cell level (source: adv funct Mater.) 2D cell culture system is widely used to study the anti-tumor ability of drug delivery system, but to some extent, it ignores the time and space complexity of solid tumor growth Next, the author uses a more advanced three-dimensional tumor cell sphere system to simulate the real tumor growth, and then uses mteng combined with micro needle electrode to implement electric field stimulation (Figure 5) Through the finite element analysis, a high voltage electric field of up to 5kV / cm can be generated around two microneedles with 400 μ m spacing Using fluorescence microscope, the author observed that the drug loaded erythrocytes can effectively enter into the three-dimensional tumor ball, which is in good accordance with the EPR effect of solid tumors (Fig 5c-e) Six groups of experimental conditions were designed The control group did not carry out any treatment (control), erythrocytes without drug and mteng electric field group (RBC + EF), free adriamycin group (DOX), adriamycin and mteng electric field group (DOX + EF), drug loaded erythrocytes group (d @ RBC) and drug loaded erythrocytes with mteng electric field group (d @ RBC + EF) TUNEL of frozen section was used Staining was used to evaluate the cell killing ability of each experimental group to three-dimensional tumor ball (Fig 5F) No apoptosis was found in RBC + EF group as in the control group; about 15% apoptosis was found in DOX group, DOX + EF group and D @ RBC group The proportion of dead tumor cells in D @ RBC + EF group was 41.4%, showing the most excellent killing ability of tumor cells Then, the three-dimensional tumor growth curve showed that the tumor cells in DOX + EF group and D @ RBC group grew to 200% of the original volume eight days later, the tumor cells in DOX group grew to 300% of the original volume, the tumor cells in control group and RBC + EF group grew to 500%, and the tumor cells in D @ RBC + EF experimental group stopped growing in the first few days, which proved that mteng The controlled drug delivery system also has a highly effective killing effect on tumor cells at the three-dimensional tumor sphere level Figure 5 The application of electric field controlled RBC delivery system in three-dimensional tumor cell sphere (source: adv funct Mater.) finally, the authors studied the antitumor effect of mteng controlled RBC drug delivery system in BALB / C tumor bearing nude mice model (Figure 6) As shown in Fig 6a, the author uses the same micro needle stimulation device as in the three-dimensional cell ball experiment The imaging system of small animals showed that after 6 hours of tail vein injection, the drug loaded red blood cells reached the liver and tumor site, and the content of liver and tumor site was the same 48 hours later