Patent Abstract:
a nano - sized hydrogel is made of a water - soluble chain containing carboxylic acid moieties and polyethylene side chains . such a nanogel is applicable as a cancer - drug delivery agent or an imagining agent , where either a cancer drug , such as cisplatin , or an imaging agent , such as gd3 +. the complexation of the cancer drug or the imaging agent with the carboxyl moieties leads to the hydrogel formation .

Detailed Description:
cis - dichiorodiamineplatinum ( ii ) ( cisplatin or cddp ) is an example of an anticancer drug that can induce cancer drug resistance . [ scanlon , 1991 .] kataoka and co - workers incorporated cisplatin into block copolymer micelles to circumvent the drug resistance . the micelle - encapsulated cisplatin had an improved cytotoxicity . [ noshiyama , 2003 ; nishiyama , 1999 ; nishiyama , 2001 .] we synthesized a water - soluble carboxylic acid - containing poly ( ester ) grafted with peg side chains . in water , cddp complexes with the carboxylic acid of the poly ( ester ) and forms nanogel domains of about 100 - 200 nm that can be used for controlled delivery of ccdp or other drugs to cancer tissue . the reaction scheme for producing 2 , 2 - bis ( acryloxymethyl ) propionic acid is illustrated in fig1 . 2 , 2 - bis ( hydroxymethyl ) propionic acid ( 10 . 1 g , 0 . 075 mol ) was stirred at 0 - 5 ° c . in dried dichloromethane . triethylamine ( 15 . 2 g , 0 . 15 mol ) was added with stifling . acryloyl chloride ( 13 . 64 g , 0 . 15 mol ) was added dropwise to the solution in 1 . 5 h . the resulting mixture was stirred for 0 . 5 h and then filtered . the filtrate was concentrated by removal of the solvent under vacuum and the residue was dissolved in 50 ml na 2 co 3 aqueous solution ( 10 % w / v ). hydrochloric acid ( 6n ) was then dropped in with vigorous stirring , until the ph reached 2 . 0 . finally , dichloromethane ( 3 × 50 ml ) was added to the solution . the dichloromethane solution was then concentrated by removal of the solvent under vacuum . the crude product was recrystallized with ethyl acetate / hexane mixed solvent and yielded the 2 , 2 - bis ( acryloxymethyl ) propionic acid as white crystals . 1 h nmr ( cdcl 3 , 400 mhz ) δ = 11 . 47 ; ( s , 1h ); 5 . 7 - 6 . 8 ; ( m , 6h ), 4 . 4 ; ( s , 4h ), 1 . 38 ; ( s , 3h ). the reaction scheme for synthesizing the peg macromonomer is illustrated in fig2 . poly ( ethylene glycol ) methy ether ( mn ca . 2000 ) ( 10 . 0 g , 0 . 005 mol ) and 2 , 2 - bis ( acryloxymethyl ) propionic acid ( 3 . 03 g , 0 . 0125 mmol ), n , n - dicyclohexylcarbodiimide ( dcc ) ( 2 . 588 g , 0 . 0125 mol ), 4 - dimethylaminopyridine ( 0 . 1 52 g , 0 . 00125 mol ) and a polymerization inhibitor were dissolved in 50 ml of dry dichioromethane and stirred at room temperature for 72 h . the mixture was then filtered and washed with a small volume of dichioromethane . the filtrate was precipitated in ether , and purified by reprecipitation to give the product as white powder . the reaction scheme for synthesizing poly ( ester )- graft - peg is illustrated in fig2 . 2 , 2 - bis ( acryloxymethyl ) propionic acid ( 0 . 242 g . 0 . 001 mol ), peg macromonomer ( 2 . 224 g , 0 . 001 moi ) and piperazine ( 0 . 172 g . 0 . 002 mol ) were dissolved in 20 ml of n , n - dimethylformamide and stirred at room temperature for 7 days . the molecular weight and polydispersity of the polymer were measured by gpc and calibrated with peg standards . the reaction scheme for synthesizing the nanogels is illustrated in fig3 . poly ( β - aminoester )- graft - peg and cddp were dissolved in distilled water ([ cooh ]/[ cddp ]= 7 . 4 ) and stirred for a certain period of time at room temperature or heated at 70 ° c . for 10 minutes and then kept stirring at room temperature for 12 h . the size of the formed nanogels was evaluated by nanosizer ( malvern instruments ). the graft copolymers with peg side chains ( m n = 2000 ) was prepared by direct condensation . the peg chain density was controlled by the molar ratio of 2 , 2 - bis ( acryloxymethyl ) propionic acid to the peg macromonomer . the pendent carboxyl acid groups are used for the complexation with cddp . composition of the copolymer was measured with 1 hnmr by the ratio of the och 2 ch 2 signal intensity in peg ( 3 . 60 ppm ) and that of ch 3 − in 2 , 2 - bis ( acryloxymethyl ) propionic acid ( 1 . 38 ppm ). polyester - graft - peg with varied contents can be synthesized in a similar method . the peg grafted polymer and cddp reacted in distilled water . the carboxylic groups of the graft - copolymer complexed with cddp , and thus the polymer was crosslinked to form the gel core , while the peg chains formed the hydrophilic corona ( fig3 ). the average size was 220 - 240 nm ( fig4 ). heating can decrease the size of the nanogel . when heated at 70 ° c . for ten minutes , the average size of the nanogels was reduced to 150 - 160 nm . the nanogels are negatively charged . the negatives and the peg outer layer impart “ stealth properties ” to the nanogels suitable for in vivo drug delivery to cancerous tissues via the epr effect . particularly , the polymers alone showed no or little cytotoxicity . the cisplatin - containing nanogels had low in vitro cytotoxicity to skov - 3 ovarian cancer cells compared to free cisplatin . similar phenomena were reported in the cisplatin - containing micelles and other water soluble cisplatin conjugates ( cabral et al . 2005 ; nishiyama et al . 2003a ; nishiyama et al . 2003b ; nishiyama et al . 1999 ). however , the nanogels had similar in vivo anticancer activity to cisplatin tested in nude mice inoculated with skov - 3 tumors . grafting targeting groups to the nanogels is expected to further increase the anticancer activity . in conclusion , the reaction of cddp and peg - grafted copolymer in distilled water led to the spontaneous formation of cddp - incorporated micelles . the size of the micelles can be reduced by heating . these nanogels are useful for drug delivery . the foregoing description and drawings comprise illustrative embodiments of the present inventions . the foregoing embodiments and the methods described herein may vary based on the ability , experience , and preference of those skilled in the art . merely listing the steps of the method in a certain order does not constitute any limitation on the order of the steps of the method . the foregoing description and drawings merely explain and illustrate the invention , and the invention is not limited thereto , except insofar as the claims are so limited . those skilled in the art who have the disclosure before them will be able to make modifications and variations therein without departing from the scope of the invention . bogman , k . ; 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