Kinetics of Threading α-Cyclodextrin onto Cationic and Zwitterionic Poly(bola-amphiphiles)

Abstract

The amphiphilic polymers, poly(iminoundecamethylene), poly((N-methylimino)undecamethylene), poly((N,N-dimethylammonio)undecamethylene), and poly((N-methylimino)undecamethylene-N-oxide) were synthesized from nylon-11 by BH 3 reduction of amide groups to amino groups and subsequent methylations. The poly(N-oxide) was obtained by H 2 O 2 oxidation of the polymeric tertiary amine. Since the polymers and their inclusion compounds were water-soluble, threading kinetics of R-cyclodextrin rings onto these polymers could be investigated by 1 H NMR. Kinetics were fitted by an empirical root exponential association function Y ) Y ∞ (1 exp(-sqrt(5.3t/t 90 ))). The time t 90 , necessary to reach 90% completion of the threading process, was taken as a measure of the steric hindrance exerted by the hydrophilic groups along the polymer chain. The vaIues of t 90 decreased by more than 3 orders of magnitude as the diameters of the hydrophilic groups decreased from 5.5 to 4.3 Å.

Spontaneous Assembly into Pseudopolyrotaxane Between Cyclodextrins and Biodegradable Polyphosphoester Ionomers

“…This is consistent with the poly(ε‐lysine)/α‐CD system, in which the yield of PPRX is not altered with the ionic strength of the solution . Additionally, it is known that the polymers bearing long alkyl chains along the main chain are favorable for PPRX formation, due to the hydrophobic interaction between alkyl chains and inner cavity of CDs, which stabilizes the inclusion complex . For example, Wenz et al have found that α‐CD can threaded onto the polymers even though bearing quaternary ammonium salt or zwitterionic groups along polymer main chain .…”

Macromolecular Recognition and Macroscopic Interactions by Cyclodextrins

“…Steric hindrance and the hydrophilicity of the cationic groups stabilize the polypseudorotaxanes between the polyelectrolyte and α-CD. [29] …”

Cellular delivery of polynucleotides by cationic cyclodextrin polyrotaxanes

“…Ionenes are only slowly complexed by CD at elevated temperatures (70°C), due to steric hindrance from the bulky dimethylammonium groups. At lower temperatures, 25-37°C, they are stable for a limited period of time in aqueous solution (1 -10 days) [27,28]. Not only native CDs but also cationic CD derivatives can be threaded onto ionenes.…”