Preparation And Properties Of PH/Temperature Double Response Smarts

As we all know,cancer is one of the major killers of human health and life,and also the most common malignant tumor.Cancer has many biological characteristics,including abnormal proliferation,loss of control of cells differentiation during growth,and cell transfer.Oral medication,a simple,convenient,and effective way,is one of the most important ways to cure cancer by chemotherapy and targeted therapy.It can be taken with you and reduce the expensive cost like hospitalization.However,most anti-tumor drugs still have some defects,including the high price,different efficiency and fast release rate,side effects on the survival of normal cells,and poor water solubility,etc.Faced with various disadvantages of oral drugs,some scholars proposed corresponding solutions,among which the most effective way is to discover a non-toxic drug delivery carrier to control drug release and improve the utilization rate of oral anticancer drugs.In recent years,many scholars have made use of the stimulation sensing ability of intelligent hydrogels,the external factors such as pH value,temperature,ion strength,light intensity,pressure,electric field,magnetic field and other stimulation changes will produced reversible responses to take intelligent hydrogels as carriers of oral drugs.However,with low mechanical strength and narrow sensitivity to stimulation,it is a huge challenge to use most of intelligent hydrogels as a carrier of oral anticancer drugs.In general,scientists use crosslinking agents to enhance the mechanical strength of hydrogels,but this method has some limitations since most chemical crosslinkers are toxic and have poor compatibility.For this,how to improve the mechanical strength of intelligent hydrogels is a problem that people have been exploring.In order to solve the above problems,this thesis introduces a new,efficient and convenient aqueous solution polymerization method,and appliesphysical crosslinking method to produce two kinds of intelligent hydrogels with high mechanical strength and sensitivity,P(CS-co-AA-co-DMAEMA-co-PEG)pH responsive intelligent hydrogels and P(CS-co-AA-co-DMAEMA-co-OEGMA)pH-temperature sensitive intelligent hydrogels.It studies the influence of monomer composition on hydrogels,different conditions on hydrogels swelling,and also drug release behavior of hydrogels.The research contents and research conclusions are as follows:(1)Taking chitosan as raw materials,AA and DMAEMA as pH sensitive monomer,and adding PEG macromolecular monomer with good biocompatibility for improving the effect of the gel swelling,it produces a series of new pH sensitive P(CS-co-AA-co-DMAEMA-co-PEG)hydrogels by aqueous radical polymerization method without any chemical crosslinking agent.It studies the structure and morphology of hydrogels by FTIR,XRD,TGA/DSC,and SEM,and also examines swelling and rheological properties,compressive strength,pH-sensitivity and salt solution responsiveness of the hydrogels.BSA is taken as drug model to observe drug sustained-release behaviors of chitosan matrix P(CS-co-AA-co-DMAEMA-co-PEG)hydrogels under normal circumstances.It compares and BSA medicine carrying hydrogels with free BSA,showing that the hydrogels has a good inhibition on the growth of liver cancer cell.Therefore,this ph-sensitive hydrogels is a good anti-cancer drug carrier.(2)A series of ph-temperature sensitive chitosan semi-cross network hydrogels were produced by aqueous radical polymerization with chitosan as raw material,AA as ph-sensitive monomers,DMAEMA and OEGMA as temperature-sensitive monomers.It studied the structure and morphology of hydrogels by FTIR,XRD,TGA/DSC and SEM.In addition,rheological properties,compressive strength,temperature sensitivity,pH sensitivity and salt solution responsiveness of hydrogels wre also investigated.The influence of DMAEMA and OEGMA on their temperature sensitivity was studied by fixing the amount of AA while the influence of the content of AA on their pHsensitivity by fixing the content of DMAEMA and OEGMA.Using BSA as drug model,the drug release behavior of P(cs-co-aa-co-dmaema-co-oegma)hydrogel,and good swelling behavior in aqueous solution at different temperatures were investigated In addition,the comparison between medicine carrying hydrogels and free drugs shows that such hydrogels have great potential value in drug release and other fields.