The Culture Of Tumor Spheres Based On Electrospinning Technology And The Detection Of Endogenous Hydrogen Sulfide Gas

Cancer has been a serious threat to human health.Metastasis and recurrence of cancer is the crucial reason of the failure of cancer treatment,in which cancer stem cells（CSCs）play a very important role.Cancer stem cells can resist medical treatement and radiational therapy,so we can not kill CSCs effectively.Therefore,the accurate identification and targeted treatment to CSCs is of important clinical significance for the prevention,early diagnosis and treatment of cancer.In my thesis,we studied the phenotypic differences between CSCs and cancer cells,including the growth characteristics of cancer cells in vitro and the difference of the content of hydrogen sulfide generated between CSCs and cancer cells.We fabricated polycaprolactone（PCL）electrospun fibrous materials and polycaprolactone electrospun fibrous materials with small wells（PCL with wells,wPCL）by electrospinning technology.That has the advantages of large aspect ratio,high surface energy,good air permeability and no biotoxicity.Thus,we developed a method for culturing tumor spheroids and another method for detection of endogenous hydrogen sulfide gas.The specific works as follows:（1）We provided a method for culturing tumor spheroids based on the growth characteristics of cancer cells cultured in vitro.First of all,we treated with surface of aluminum foil to generate a hydrophobic nature and added drops of water on the surface of hydrophobic aluminum foil.Drops of water would form spherical ice at low temperature conditions.Then the amount of icy ball and the distance between the icyballs could be controlled by controlling the amount and location of drops of water.Finally,the wPCL fibrous membrane with a plurality of specific trait and size of microwells,was prepared by icy ball as the template.Compared with the three-dimensional materials prepared by the traditional metal or silicon productsas the template,three-dimensional materials preparated by icy ball as a template has its own advantages,such as simple operation,good biocompatibility,no need to remove the template and low cost.Subsequently,the experiment of formation of tumor spheroids was chosen by hanging drop culture method.The cell suspension was dropped into the microwell of wPCL and turned over to form a hanging drop.The microwell structure on the wPCL was able to maintain the stability of the droplets and thus reduce the interference to tumor formation.The electrospin fibrous membrane has a good gas permeability and thus ensures the exchange of 02 and CO₂ between the cell suspension and the surrounding environment.（2）In view of the fact that the content of H₂S is different between CSCs and common cancer cells,a method has been developed for detecting endogenous H₂S by gold-silver core-shell nanorods（AuNR-Ag）modified electrospun fibrous mat sensor.In this experiment,AuNR-Ag particle has local environment-dependent optical properties.Plasma resonance of AuNR-Ag particle at long wavelengths is highly sensitive to local refractive index changes.AuNR-Ag particle exhibited a visual color change or redshift of wavelength in the presence of very small amounts of sulfide.The electrospun fibrous mat has the advantages of large specific surface area and good gas permeability.Thus,it is hoped that the sensitivity of gas detection would be further improved.Therefore,AuNR-Ag modified electrospun fibrous mat sensor was prepared in this experiment.The reaction of the sensor with H₂S gas can produce Ag2S.Then,the redshift of the spectrum was occured and the rate of redshift of the wavelength was increased with the increase of the concentration of external H₂S.In a certain range,a good linear relationship between logarithm of the concentration of H₂S and the redshift wavelengthΔλmax was obtained.So this method can be used to detect H₂S.In this experiment,this method has detected the H₂S gas released from living cells.