Intrinsic Electrical Signal Based On Piezoelectric Biomaterials And Study Of Its Regulation In Angiogenesis

Angiogenesis plays a crucial role in both physiological and pathological processes.Traditional biomaterial strategies for regulating angiogenesis focus on biomimetic design of mechanical properties,as well as loading and release of biochemicals,and related research has made some progress.Bioelectrical signals,as physical cues widely exist in organisms,play an important role in the communication between cells,tissues and organs.In recent years,researches have also shown that exogenous electrical stimulation can effectively regulate angiogenesis.However,the effect and mechanism of the electrical properties of biomaterials on angiogenesis are still unclear.Piezoelectric materials,as a kind of non-toxic and biocompatible materials,with the capacity to induce the regular arrangement of electric domain orientation after polarization,thereby forming different static electrical potential on their surfaces.In addition,piezoelectric materials can also exhibit unique mechano-electrical responses under the action of external forces,generating dynamic electrical field.In view of this,this article aims to establish wireless electrical stimulation research models based on piezoelectric biomaterials to explore the influence of intrinsic electrical signals and their spatial distribution on angiogenesis,and to reveal the molecular mechanism of intrinsic electrical signals on endothelial cell proliferation,adhesion,migration and angiogenesis both in vitro and in vivo.It is intended to meet the needs of tissue repair and tumor treatment,providing ideas and technical approaches for clinical development of non-invasive wireless stimulation strategies.The specific research contents are as follows:（1）Inspired by the intervention of exogenous bioelectricity in angiogenesis,the conception of regulate angiogenesis by surface electrostatic potential of biomaterials is proposed.Taking advantage of the stable electrical properties,and uniform structure and composition of piezoelectric single crystal,lithium niobate piezoelectric single crystals were selected as substrates to construct homogeneous surface electrostatic potential models with different intensities.The results showed that the phase composition,structural components and surface roughness of the lithium niobate piezoelectric single crystal had no obvious change after polarization,but showed an increase of about 3 times in the surface electrostatic potential.In vitro cell experiments showed that high surface electrostatic potential not only facilitated endothelial cell proliferation,adhesion,and spreading,but also promoted cell migration and angiogenesis.Furthermore,the potential mechanism of surface electrostatic potential regulating endothelial cell behavior was revealed,that is,the up-regulation of intracellular calcium ion([Ca²⁺]_i)level activated the formation of actin and focal adhesion protein,thereby regulating endothelial cell migration and angiogenesis.This study provides data support for the development of strategies for regulating angiogenesis based on intrinsic electrical signals of biomaterials.（2）Inspired by the heterogeneity of the electrical microenvironment of living organisms,the conception of constructing a controllable micro-zones electrostatic field to regulate angiogenesis is proposed from a bionic perspective.Using the principle that the phase of piezoelectric ceramics determines piezoelectricity,potassium sodium niobate piezoelectric ceramics were selected as substrates to construct heterogeneous micro-zones electrostatic field models with different intensities and periods.The results showed that laser irradiation increased the proportion of tetragonal phase in potassium sodium niobate piezoelectric ceramics and reduced the piezoelectricity of the selected zones.The polarization treatment further increased the surface potential difference between different zones,and finally formed micro-zones electrostatic fields.In vitro cell experiments showed that the micro-zones electrostatic field could induce the directional arrangement and elongation of endothelial cells,up-regulate the expression of vascular endothelial growth factor（VEGF）and endothelial nitric oxide synthase（e NOS）,and effectively promote cell migration and angiogenesis.In vivo chick embryo allantoic membrane model also confirmed that the micro-zones electrostatic field was beneficial to the construction of the vascular network.Furthermore,the mechanisms of micro-zones electrostatic fields regulated endothelial morphology and angiogenesis were elucidated.On the one hand,the micro-zones electrostatic fields could up-regulate[Ca²⁺]_i levels through Piezo1channel and phosphatase C pathway,thereby activating the downstream e NOS/nitric oxide（NO）pathway to promote endothelial cell migration to form blood vessels.On the other hand,the micro-zones electrostatic fields could mediate cell rearrangement and elongation by regulating the gradient distribution of[Ca²⁺]_i,providing the possibility for targeted recruitment.This study provides a new idea for the design of biomaterials with bionic electrical properties,and also reveals the key role of[Ca²⁺]_i in guiding angiogenesis in response to electrical signals.（3）Based on the beneficial regulation of angiogenesis by static electrical signals of materials,it is further proposed to construct a dynamic electrical field to disturb the tumor electrical microenvironment to induce normalization of the pathological vascular system.Taking advantage of the characteristics of piezoelectric nanoparticles with high spatial resolution and easy uptake by cells,barium titanate piezoelectric nanoparticles with mechano-electrical response characteristics were developed,and the dynamic electric field models of different intensities at the nanoscale interface were constructed by low-intensity pulsed ultrasound（LIPUS）.The results showed that the mechano-electrical conversion performance of barium titanate piezoelectric nanoparticles was enhanced after polarization,and high pulsed open-circuit voltage could be generated under the driving of LIPUS to realize the dynamic electrical stimulation at the nanoscale interface.In vitro cell experiments showed that dynamic electrical stimulation could disrupt the[Ca²⁺]_i gradient,thereby downregulating the angiogenesis-related e NOS/NO pathway,and subsequently inhibiting endothelial cell migration and angiogenesis.In vivo tumor-bearing mouse models demonstrated that dynamic electrical stimulation normalized tumor vasculature by optimizing vascular structure and function.Ultimately,dynamic electrical stimulation potentiated the anti-tumor efficacy of chemotherapeutic drug doxorubicin（DOX）,which was approximately 1.8 times that of single DOX treatment.This study indicates that the bioelectrical homeostasis of endothelial cells can be regulated to induce tumor vascular normalization,which has broad application prospects in the clinical auxiliary treatment of malignant tumors.