Preparation Of Polydopamine/silver Composite Nanoparticles And Its Application In Cell Fluorescence/SERS Dual Imaging And Drug Controlled Release

Fluorescence imaging has been widely used in the field of biology and medicine,due to the advantages of good repeatability,high sensitivity,rapid micro imaging and so on.Compared with the fluorescence method,Surface-Enhanced Raman Scattering(SERS)owns its advantages,including narrow line width,high signal to noise ratio,low possibility of photobleaching and the ability for molecular identification.Thus,this technique gradually steps into one of the hot topics in the field of biological detection in recent years.However,SERS imaging is relatively slow.Fluorescence and SERS dual imaging could combine their advantages together,and make up the limitations.Furthermore,the preparation processes of traditional fluorescence/SERS double response composite nanoparticles are complex and Raman molecular is easy to leak,which bring difficulties to Raman analysis.Therefore,it is necessary to develop simple preparation of the composite nanoparticles in this field.Dopamine can occur aggregation in the alkaline aerobic environment to generate polydopamine(PDA).And PDA can be coated on the surface of many materials because of its own adhesive property.The functional groups on PDA,such as amine and phenolic hydroxyl,provide a way to modify the basal surface.In this paper,we prepared a simple class of new composite nanoparticles with fluorescence/SERS double signals using the adhesion and chemical reactivity of PDA.Those particles could emit fluorescence and SERS signals by choosing appropriate excitation light.The composite nanoparticles exhibited good imaging ability for cancer cell as well as good pH responsiveness value during the drug release and specificity.The research contents are as follows in detial:task 1.Silver nanoparticles(Ag NPs)were first used as SERS enhancement base and a thin layer of PDA was then coated on Ag NPs.The Rhodamine6 G was used as fluorescence source to generate fluorescence signal.After optimizing conditions,we obtained the excellent complex nanoparticles,which had both fluorescence and SERS signals.Applying the composite particles to cells,clear confocal fluorescence and strong SERS imaging were obtained.Meanwhile,the response of the pH value during the drug release was simulated.task 2.Based on the task1,the composite nanoparticles by instead R6 G with Doxorubicin(DOX)-ananticancer drug were synthesized.The drug could release with a large quantity in neutral environment,leading damage to normal cells.In order to reduce the release in neutral environment and magnify the differentiation in release between acidic and neutral environment,we embedded polyethylene imine(PEI)on the surface of PDA by using its chemical reactivity.Because of the PEI's space conformation strongly depends on the pH value of medium,it would greatly promote the PEI modified composite nanoparticles applying in the study of high sensitive pH response as well as improving the pH response of R6G/DOX release.task 3.Transferrin(Tf),a kind of beta-globulin,can be specifically combined with cell surface of Transferrin Receptor(TR),keeping the balance of iron ions in the organism.Besides,it is an indispensable growth factor in cell growth and proliferation.Most of the cancer cells have higher iron absorption rate and the quantity of TR on the surface of cancer cells is significantly higher than normal cells.Thus,Tf can be used to identify and diagnose tumor.Based on the task 2,composite nanoparticles crossed bonding glutaraldehyde(GA)by reacted with PEI.When Tf introduced,we synthesized the composite nanoparticles with targeting property.And the composite nanoparticles show specificity in the cell experiments.