Preparation Of Dialdehyde-?-Cyclodextrin And Its Applications

?-Cyclodextrin(?-CD)has a special cylindrical structure with a hydrophilic outer rim and a hydrophobic inner ring,which can conclude many small molecular substances through the host-guest reaction.?-CD has been extensively researched and applied in the fields of medicine,textile,food,nanotechnology,membrane technology and so on.However,?-CD has strong rigidity,poor water solubility,and no functional groups.These shortcomings limit the application of?-CD and guide people to modify it.In this paper,sodium periodate was used as an oxidant to oxidize?-CD preparing dialdehyde-?-cyclodextrin(DA-?-CD).The introduction of aldehyde groups into the cyclodextrin molecule destroyed the complete hydrogen-bond ring in the original molecule and improved the water solubility.By changing the conditions of sodium periodate to oxidize?-CD,the effects of sodium periodate/?-CD molar ratio,oxidation temperature and oxidation time on DA-?-CD's aldehyde group content and inclusion ability were explored.With the introduction of aldehyde groups and improved water solubility,DA-?-CD has become an ideal raw material for the preparation of medical drug-loaded hydrogels.Carboxymethyl chitosan(CMCS)is a water-soluble chitosan derivative,which has strong antibacterial properties,good biocompatibility.In recent years,it has received great attention in medicine.Using DA-?-CD and CMCS as raw materials and phenolphthalein(PhP)as a model drug,DA-?-CD/CMCS drug-loaded hydrogels were prepared and their drug release properties were studied.On the other hand,there have been many studies to fix?-CD on fabrics by different methods to make them functional.Wool is a kind of fabric with excellent properties,and grafting?-CD on it would increase its added value.Through the Schiff base reaction between the aldehyde group of DA-?-CD and the amino group of wool,DA-?-CD was fixed on the wool fabric.The influence of the modification process on the grafting rate was explored.The main results are as follows:(1)The DA-?-CD obtained by oxidizing?-CD with sodium periodate does contain aldehyde groups.As the amount of sodium periodate used increased,the content of aldehyde groups increased.The introduction of aldehyde groups weakened the crystallinity of cyclodextrin,increased the water solubility,and weakened the inclusion capacity for phenolphthalein.When the molar ratio of sodium periodate/?-CD is 1:1,1:2,1:3,the aldehyde group content of DA-?-CD obtained by oxidation is 1.68,2.92,4.02 mmol/g,respectively;the solubility is 1.96,4.60and 17.52 times of?-CD,respectively;the inclusion constant is about 50%,40%and 20%of?-CD,respectively.As the degree of oxidation increased,the solubility of DA-?-CD increased more than the decrease in inclusion capacity,so the solubilizing effect of DA-?-CD on PhP was enhanced.(2)Hydrogels were prepared by cross-linking DA-?-CD and CMCS.The higher the aldehyde group content of DA-?-CD,the faster the hydrogel's gel speed,the stronger the gel formed,and the larger the pore size.Glyoxal/CMCS hydrogel was used as a control group to study the release performance of PhP.Compared with the control group,the DA-?-CD/CMCS hydrogel has a faster release rate for its loaded PhP.Only 19.2%of PhP loaded in glyoxal/CMCS hydrogel was released within 24 hours.On the same time,about 95%of PhP loaded in DA-?-CD/CMCS hydrogel was released within 24 hours,about 50%was released within 2 hours and approximately 90%was released within 12 hours.The increase of aldehyde content on DA-?-CD slowed the release of PhP in DA-?-CD/CMCS hydrogel to a certain extent.(3)When the molar ratio of sodium periodate/?-CD was 1:1,the increase in temperature and reaction time would increase the aldehyde group content of the oxidation product and decreased the inclusion constant.When using DA-?-CD to treat wool,the reaction temperature,reaction time and concentration of DA-?-CD would affect the grafting rate of the product.The optimized reasonable grafting process conditions were 15g/L of DA-?-CD concentration,30 ~oC of reaction temperature and 1h of reaction time.The initial weight gain rate of the modified wool obtained under this condition was 2.27%,and it was reduced to 1.12%after 5 washings cycles,showing good washing fastness.In addition,after fixing on the wool fiber,DA-?-CD's inclusion capacity decreased by 60%,but it still had inclusion ability.