Preparation And Property Of The Poly (Ethylene Glycol) Modifief Layered Double Hydroxides

Layered double hydroxides(LDHs),also called hydrotalcite-like compounds,have been widely applied in various aspects such as adsorption,catalyst,waste de-ionized water treatment,drug carrier,and so on.The interlayer gallery of LDHs may be considered as a microvessel for the intercalation of some drug molecules to fabricate drug-LDHs nanohybrids.Herein,we synthesized various carboxylic or sulfonic terminated poly(ethylene glycol)derivatives with a molecular weight of 0.6K,2K,5K,respectively.These PEG derivatives as modifier were incubated with LDHs or drug/LDHs in de-ionized water solution to get the PEG modified LDHs.The dispersity of these modified LDHs and floxuridine/LDHs nano-hybrids was largely enhanced and the release properties of modified drug/LDHs nanohybrids could be better controlled in the release systems These hydrophilic and biocompatible PEG modifiers can endow the LDHs particles a good dispersity in de-ionized water and even a stealth ability in the drug delivery in-vivo as long-circulation nanovehicles.The main contents of this paper are as follows.1.Preparation and Characterization of PEG DerivativesPEG derivatives with different molecular weight were prepared including(1)polyethylene glycol monomethyl ether sulfonate(MPEGS),(2)Poly(ethylene glycol)monomethyl ether sebacate(MPEG-SA)and(3)polyethylene glycol sebacate folic acid(FA-PEG-SA).FT-IR and 1H NMR characterizations demonstrated that these target polymer derivatives were successfully synthesized.2.Surface modification of LDHs by PEG derivativesThe as-synthesized PEG derivatives were used to incubate with LDHs at different reaction time,temperature and reactant feed ratio of LDHs in de-ionized water solution for the surface modification.The PEG/LDHs products were characterized by FT-IR,XRD,TEM,AFM,DLS,Zeta potential,elemental analysis,and TGA.The results showed that PEG molecules were not intercalated into the interlayers of LDHs,while they were adsorbed on the surfaces of LDHs by electrostatic,hydrogen bond and hydrophobic interactions.We also found that the edges of PEG modified LDHs changes into more smooth and more importantly their Zeta potential was reversed into a highly negative value which resulted in the high dispersity and stability of the PEG modified LDHs.3.Surface modification of the drug/LDHs nanohybrids by PEG derivativesThe PEG derivatives were used to modofy the floxuridine-LDHs nanohybrids which were synthesized by co-precipitation method.The modified drug/LDHs still had a drug-loading of maximum 38%.The drug release of the PEG modified drug/LDHs nanohybrids at pH = 4.8 and 7.2 showed that the drug release rate of was obviously slow than those without PEG modification and the dispersity of PEG modified drug/LDHs nanohybrids was highly enhanced.Therefore,the surface modification of drug/LDHs nanohybrids by PEG showed a posive contribution for the application of the drug/LDHs nanohybrids.