Abstract: A heterobifunctional monodispersed polyethylene glycol represented by the formula (1): wherein X1 and Y1 are each an atomic group containing a functional group capable of forming a covalent bond upon a reaction with a functional group present in a biofunctional molecule, the functional group contained in the atomic group X1 and the functional group contained in the atomic group Y1 are different from each other; R1 is a hydrocarbon group having from 1 to 7 carbon atoms or a hydrogen atom; n is an integer of 3 to 72; 1 is an integer of 2 to 72; and A1, B1 and C1 are as defined herein.

Abstract: A method for purifying a specific trityl group-containing monodispersed polyethylene glycol from a mixture containing the trityl group-containing monodispersed polyethylene glycol and a specific ditritylated impurity. The method includes performing steps (A), (B) and (C). Step (A): a step of esterifying the hydroxyl group of the trityl group-containing monodispersed polyethylene glycol by a specific method; Step (B): a step of extracting the esterified compound by a specific method; and Step (C): a step of hydrolyzing the esterified compound to obtain the trityl group-containing monodispersed polyethylene glycol.

Abstract: A hydrophilic polymer derivative having a cyclic benzylidene acetal linker represented by the following formula (1): wherein R1 and R6 are each independently a hydrogen atom or a hydrocarbon group; R2, R3, R4 and R5 are each independently an electron-withdrawing or electron-donating substituent or a hydrogen atom; X1 is a chemically reactive functional group; P is a hydrophilic polymer; s is 1 or 2, t is 0 or 1, and s+t is 1 or 2; w is an integer of 1 to 8; and Z1 and Z2 are each independently a selected divalent spacer.

Abstract: A biodegradable polyethylene glycol derivative in which a polyethylene glycol chain is linked by an acetal linker capable of accurately controlling the hydrolysis rate under different pH environments in the living body, and whose division rate into a polyethylene glycol chain of low molecular weight in the living body can be accurately controlled. The biodegradable polyethylene glycol derivative is represented by formula (1) or formula (2) as described.

Abstract: A heterobifunctional monodispersed polyethylene glycol represented by formula (1) which has two adjacent monodispersed polyethylene glycol side chains and does not have a chiral center in the molecular structure: wherein X1 and Y1 are each an atomic group containing a functional group capable of forming a covalent bond upon a reaction with a functional group present in a biofunctional molecule. R1 is a hydrocarbon group or the like. n is an integer of 3 to 72. A1 represents -L1-(CH2)m1— or the like, L1 and L2 represent each an ether bond or the like, and m1 and m2 each independently represent an integer of 1 to 5. B1 represents -L3-(CH2)m3— or the like, L3 and L4 represent an amide bond or the like, and m3 and m4 each independently represent an integer of 1 to 5. Also disclosed is an antibody-drug conjugate including the heterobifunctional monodispersed polyethylene glycol.

Abstract: To provide a hydrophilic polymer derivative having a novel linker technique which is able to from a hydrophilic polymer pro-drug of a drug containing an amino group or the like in order to overcome the restrictions of conventional hydrophilic polymer pro-drugs.

Abstract: A degradable polyethylene glycol derivative represented by formula (1). R1, R2, and R4 represent each independently a hydrogen atom or a hydrocarbon group having from 1 to 6 carbon atoms, and at least one of R1, R2, R3 and R4 is the hydrocarbon group; P1 is a straight-chain or branched polyethylene glycol chain having a number of ethylene glycol units of 3 or more; P2 is a straight-chain polyethylene glycol chain having a number of ethylene glycol units of 3 or more; w is an integer of 1 to 8; u is an integer of 1 to 10; X1 is a chemically reactive functional group; and Z1, Z2 and Z3 are each independently a selected divalent spacer.

Abstract: A biodegradable hydrogel having an acetal structure whose hydrolysis rate under different pH environments in the living body can be accurately controlled. The hydrogel is obtained by crosslinking a polyalkylene glycol derivative having a cyclic benzylidene acetal structure represented by formula (1) shown below with a crosslinking agent: where R1 and R6; R2, R3, R4 and R5; s; t; s+t; P1; Z1 and Z2; W1 and X1 are as defined herein.

Abstract: A heterobifunctional monodispersed polyethylene glycol represented by the formula (1): wherein X1 and Y1 are each an atomic group containing a functional group capable of forming a covalent bond upon a reaction with a functional group present in a biofunctional molecule, the functional group contained in the atomic group X1 and the functional group contained in the atomic group Y1 are different from each other; R1 is a hydrocarbon group having from 1 to 7 carbon atoms or a hydrogen atom; n is an integer of 3 to 72; l is an integer of 2 to 72; and A1, B1 and C1 are as defined herein.

Abstract: A method for purifying a specific trityl group-containing monodispersed polyethylene glycol from a mixture containing the trityl group-containing monodispersed polyethylene glycol and a specific ditritylated impurity. The method includes performing steps (A), (B) and (C). Step (A): a step of esterifying the hydroxyl group of the trityl group-containing monodispersed polyethylene glycol by a specific method; Step (B): a step of extracting the esterified compound by a specific method; and Step (C): a step of hydrolyzing the esterified compound to obtain the trityl group-containing monodispersed polyethylene glycol.

Abstract: An antibody-drug conjugate having a cyclic benzylidene acetal linker represented by formula (1) or formula (2), wherein Y is an antibody; D is a drug; R1 and R6 are each independently a hydrogen atom or a hydrocarbon group; R2, R3, R4 and R5 are each independently an electron-withdrawing or electron-donating substituent or a hydrogen atom; s is 1 or 2, t is 0 or 1, and s+t is 1 or 2; w is an integer of 1 to 20; and Z1 and Z2 are each independently a selected divalent spacer:

Abstract: A hydrophilic polymer derivative having a cyclic benzylidene acetal linker represented by the following formula (1): wherein R1 and R6 are each independently a hydrogen atom or a hydrocarbon group; R2, R3, R4 and R5 are each independently an electron-withdrawing or electron-donating substituent or a hydrogen atom; X1 is a chemically reactive functional group; P is a hydrophilic polymer; s is 1 or 2, t is 0 or 1, and s+t is 1 or 2; w is an integer of 1 to 8; and Z1 and Z2 are each independently a selected divalent spacer.

Abstract: A biodegradable polyethylene glycol derivative in which a polyethylene glycol chain is linked by an acetal linker capable of accurately controlling the hydrolysis rate under different pH environments in the living body, and whose division rate into a polyethylene glycol chain of low molecular weight in the living body can be accurately controlled. The biodegradable polyethylene glycol derivative is represented by formula (1) or formula (2) as described.

Abstract: A hydrophilic polymer derivative having a benzylidene acetal linker whose hydrolysis rate at the pH of a weakly acidic environment in the living body can be accurately controlled. A hydrophilic polymer derivative having a benzylidene acetal linker, which is represented by the following formula (1): wherein R1 is a hydrogen atom or a hydrocarbon group; R2, R3, R4, R5, and R6 are each independently a hydrogen atom or a substituent and at least one of R3, R4, and R5 is an electron-withdrawing substituent or at least one of R2 and R6 represents a substituent; X1 is a chemically reactive functional group; P is a hydrophilic polymer; w is an integer of 1 to 8; and Z1 and Z2 are an independently selected divalent spacer.

Abstract: A lipid derivative in which a hydrophilic polymer is bound through a cyclic benzylidene acetal linker, and which can accurately control a hydrolysis rate in the weakly acidic environment of a living body to detach the hydrophilic polymer from a lipid membrane structure. The lipid derivative is represented by formula (1): wherein, R1 and R6 are each independently a hydrogen atom or a hydrocarbon group; R2, R3, R4 and R5 are each independently an electron-withdrawing or electron-donating substituent or a hydrogen atom; R7 is a hydrocarbon group having from 8 to 24 carbon atoms, an acyl group having from 8 to 24 carbon atoms, a cholesterol derivative, a glycerolipid, a phospholipid or a sphingolipid; P is a hydrophilic polymer; s is 1 or 2, t is 0 or 1, and s+t is 1 or 2; and Z1 and Z2 are each independently a selected divalent spacer.

Abstract: To provide a degradable polyethylene glycol derivative in which polyethylene glycol chains are linked by a disulfide linker capable of accurately controlling the degradation rate under different reductive environments in the living body, and whose division rate into a polyethylene glycol chain of low molecular weight in the living body is able to be accurately controlled. A degradable polyethylene glycol derivative represented by formula (1). R1, R2, R3 and R4 represent each independently a hydrogen atom or a hydrocarbon group having from 1 to 6 carbon atoms, and at least one of R1, R2, R3 and R4 is the hydrocarbon group; P1 is a straight-chain or branched polyethylene glycol chain having a number of ethylene glycol units of 3 or more; P2 is a straight-chain polyethylene glycol chain having a number of ethylene glycol units of 3 or more; w is an integer of 1 to 8; u is an integer of 1 to 10; X1 is a chemically reactive functional group; and Z1, Z2 and Z3 are each independently a selected divalent spacer.

Abstract: To provide a hydrophilic polymer derivative having a novel linker technique which is able to from a hydrophilic polymer pro-drug of a drug containing an amino group or the like in order to overcome the restrictions of conventional hydrophilic polymer pro-drugs.

Abstract: A heterobifunctional monodispersed polyethylene glycol represented by formula (1) which has two adjacent monodispersed polyethylene glycol side chains and does not have a chiral center in the molecular structure: wherein X1 and Y1 are each an atomic group containing a functional group capable of forming a covalent bond upon a reaction with a functional group present in a biofunctional molecule. R1 is a hydrocarbon group or the like. n is an integer of 3 to 72. A1 represents -L1-(CH2)m1— or the like, L1 and L2 represent each an ether bond or the like, and m1 and m2 each independently represent an integer of 1 to 5. B1 represents -L3-(CH2)m3— or the like, L3 and L4 represent an amide bond or the like, and m3 and m4 each independently represent an integer of 1 to 5. Also disclosed is an antibody-drug conjugate including the heterobifunctional monodispersed polyethylene glycol.

Abstract: An antibody-drug conjugate having a cyclic benzylidene acetal linker represented by formula (1) or formula (2), wherein Y is an antibody; D is a drug; R1 and R6 are each independently a hydrogen atom or a hydrocarbon group; R2, R3, R4 and R5 are each independently an electron-withdrawing or electron-donating substituent or a hydrogen atom; s is 1 or 2, t is 0 or 1, and s+t is 1 or 2; w is an integer of 1 to 20; and Z1 and Z2 are each independently a selected divalent spacer:

Abstract: A method for producing polyethylene glycol having a terminal carboxyl group including oxidizing polyethylene glycol represented by formula (I): CH3O(CH2CH2O)n(CH2)m—CHO with potassium peroxymonosulfate in water whose pH is adjusted to be from 6 to 8 with at least one selected from a carbonate, a phosphate, a citrate and an acetate at 5 to 40° C. to produce polyethylene glycol represented by formula (II): CH3O(CH2CH2O)n(CH2)m—COOH, wherein n is a number from 10 to 1,100, and m is 2 or 3.