Preparation Of Mesoporous Silica Composite And Their Applications In Optical Diagnosis And Treatment

Mesoporous materials have always played a very important role in the field of nanomaterials and the key research object of researchers,whether it is due to its own advantages,such as large specific surface area,adjustable pore size,and low toxicity,or attribute to it is capable of composite material.Mesoporous Si O₂ is one of the widely studied and applied materials in this category.When the mesoporous Si O₂ is used as a carrier,it has a high medicine loading rate and drug release effect.By matching the pore size of the mesoporous Si O₂ with the size of various biological materials,it can be used as a carrier for catalysts or to fix the enzyme protein.In addition,adjusting the size of the pore size or modifying different functional groups on the surface to adapt to the size and charge of the guest molecule can effectively improve the adsorption efficiency of the response target carrier.If mesoporous Si O₂ combines with precious metal materials,organic nanomaterials,magnetic nanomaterials or other materials,high-quality composite materials with dual performance can be synthesized,thereby giving mesoporous Si O₂ more possibilities.These materials can be used in optical imaging,photothermal therapy,photodynamic therapy,etc.In this paper,two composite materials Au NRs@Si O₂-PEG-IR808 and PCPDTBT@Si O₂-PEG were synthesized on the basis of mesoporous Si O₂.The cores of the materials are Au NRs which are synthesized from precious metal nanogold and a conjugated polymer PCPDTBT which fluorescence peak emission at NIR-I but in NIR-II there is a long fluorescent tail.The specific research content of this article has the following three aspects:?1?The"one-step method"based on binary mixed surfactants is used for the preparation of Au NRs:CTAB and Na OL are used together and CTAB is both a stabilizer for reaction and a soft template for micelles,while Na OL is a mild of reducing agent.The LSPR of the Au NRs which is between 650 nm and 1200 nm can be adjusted by changing the concentration of the reagents,such as increasing the concentration of Na OL and Vc,the length of the Au NRs decreases with the LSPR blue shifts;The concentration of HCl increases the length of the Au NRs,and the LSPR is red-shifted.This synthesis method is easy to operate and has good repeatability.The synthesized Au NRs have uniform morphology,good water solubility and high yield.?2?Construction of ratiometric probe and application in ROS detection:Because the ultraviolet absorption of Au NRs has the characteristics of being flexibly adjustable and not easily affected by the environment,meanwhile,in order to avoid overlapping with the UV absorption of IR808 used later,we chose the Au NRs with an absorption of 1032 nm as the core of the composite material,and wrapped a layer of mesoporous Si O₂ with a thickness of about 20 nm around.The exterior of the layer is modified with PEG chain and cyanine dye IR808,thereby synthesizing Au NRs@Si O₂-PEG-IR808composite nanoparticles.Mesoporous Si O₂ not only encapsulates the noble metal particles and exhibits non-toxicity,but the porous surface is easily modified with PEG to improve water solubility and response group IR808 which is necessary for probe.Using this ratiometric probe to detect some common ROS in vivo,with the absorption peak of the Au NRs is almost unchanged,it is found that the absorption of IR808 as a response group have a shap drop and show a ratio-type change when meeting the two ROS of·OH and ONOO^-,so these two specific ROS can be specifically detected.?3?Multimodal optical diagnosis and treatment guided by optical imaging:Because the conjugated polymer PCPDTBT which owns a fluorescence emission peak in NIR-I has a strong fluorescence signal tail in the NIR-II region,so it can be used for photothermal guidance of NIR-II treatment and photodynamic therapy.Firstly,the mesoporous Si O₂ composite material PCPDTBT@Si O₂-PEG with PCPDTBT as the core and the external modification of PEG was synthesized by silanization.The particle size of this material is 30 nm?40 nm.Through cell experiments and fluorescent imaging of mice,it can be clearly seen that this material has low toxicity and clear NIR-II in vivo imaging effect.Then the singlet oxygen yield and photothermal conversion efficiency are measured to be 5.20%and 40.5%,respectively.In addition,it can be seen in the mouse experiment that the material can clearly show the vascular veins and effectively enriched in the tumor site after 10 h,without affecting other normal tissues at the same time.After 15 days of experimental observation,the size of the tumor is clearly controlled,about 1/10 of the normal tumor in large,and about 1/8 in weight.During this period,the weight of the experimental mice did not decrease significantly,which shows good prospects for biological applications.