The Cu (I)-catalyzed “click” reaction of azides and alkynes was selected as the coupling reaction to prepare a novel biocompatible polyrotaxane (PR) conjugate

which was composed of azidofunctionalized PR backbone (Mn=1.35×105) based on α-cyclodextrins (α-CDs)/poly(ethylene glycol) (PEG) inclusion complex and amino acids protected by tert-butyloxycarbonyl (Boc) groups

that is

Boc-Gly-OH

Boc-Lys(Boc)-OH

and Boc-Phe-OH.The alkynyl groups were introduced into the aforementioned amino acids via N

N-dicyclohexylcarbodiimide(DCC)/4-(dimethylamino)pyridine(DMAP) condensation with propargyl alcohol.The click coupling reaction was demonstrated to be extremely efficient

and high conversion of azido groups

approximate 100%

was achieved in a short reaction time (within several minutes) in the cases of Boc-Gly-OH and Boc-Lys(Boc)-OH.As to the bulky Boc-Phe-OH

only part of the azido groups of the backbone was converted though the coupling reaction time was prolonged (3 h).The corresponding amino acids-PR conjugates were soluble in a wide variety of organic solvents

such as N

Ndimethylformamide

acetone

ethanol and so forth.GPC was utilized to measure the molecular weight of Boc-Lys(Boc)-PR conjugates (PR-Lys)

and the result was Mn = 1.66×105 (Mw/Mn = 1.57)

much smaller than the theoretical ones.This might be resulted from the compactly packed conformation of PRLys.The warmlike morphology of PR-Lys was observed via AFM.Other alkyne-functionalized compounds involving 4-(2-azidoethoxy)-4-oxobutanoic acid and propargyl alcohol were also attached to the PR backbone successfully.This click strategy would be a promising general method for the functionalization of PRs.