Synthesis of Chitosan Polymers

Chitosan PEG TAT

Low-molecular-weight (LMW) CS with a degree of deacetyla-
tion of 80% was obtained from Wako (Richmond, VA, USA).

NHS-PEG-Malhex of HMW 5000 was obtained from Rapp Polymere (Tuebingen, Germany).

Cysteine-terminated TAT peptide (GRKKRRQRRRGC-SH) with a MW of 1556.88

LMW CS was dissolved in 1% (v/v) acetic acid to yield a
concentration of 0.5% (w/v) CS and the pH was adjusted to
5 using 1 M NaOH. Either NHS-PEG-maleimide of PEG
with a MW of 513.50 (LMW) or 5000 (HMW) was added
to CS solutions in 10 M excess. The reaction proceeded
for 3 hours under inert conditions at room temperature.
Following the reaction, the pH was adjusted to 7 using 1 M
NaOH. The reaction was allowed to stir overnight under
similar ­conditions. Cysteine-terminated TAT was added
in a one to one or one to four molar ratio of PEG:TAT and
the reaction stirred continuously for another 4 hours under
similar conditions. Unreacted PEG and TAT were removed
from the reaction mix using a Zeba Desalting Spin gel filtra-
tion column with an exclusion limit of a MW of 7000. The
filtrate obtained consisted of CS-PEG-TAT polymer, used
to make nanoparticles under varying pH values.

Chitosan biguanidine hydrochloride

medium molecular weight (190-310 K) from sigma 448877-50G,$46.6

dissolve Chitosan in 0.15 M of either L-lactic acid or acetic acid

Chitosan (2% w/v) were dissolved in 0.15mol/L hydrochloric acid, and the desired amount of dicyandiamide (corresponding to a molar ratio of 1:2 compared with chitosan residue) was added at 100°C for 2h and then it was cooled to room temperature. The mixture was washed thoroughly with ethanol, and then dried under vacuum to constant weight to give product chitosan biguanidine hydrochloride (CGH)