Amphiphilic chitosan derivatives(N-octyl-N-mPEG-chitosan

OPEGC)were successfully synthesized via sequential Schiff base reduction reaction of chitosan with mPEG- aldehyde and n-octanal

with chitosan acting as the backbone of the grafted copolymers

and mPEG- aldehyde providing hydrophilic chain and n- octanal providing hydrophobic alkyl chain

respectively

thereby hydrophobic moiety inclining to segregate into the core of the polymeric micelles

while hydrophilic moiety forming a stabilizing interface between the hydrophobic core and the external medium.The structure of grafted copolymers with both hydrophilic and hydrophobic composition simultaneously was confirmed by characterization employing FTIR and 1H-NMR.In the subsequent procedure

water-soluble quantum dots (QDs)

widely used as nanoprobe for medical application

were achieved by incorporation of QDs inside the polymeric micelle core through the hydrophobic interaction between the acyl chain ligand capped on the QDs and the hydrophobic inner core of the polymeric micelles.The size and distribution of the polymeric micelle was determined by dynamic light scattering (DLS)

as well the effect of the amount of alkyl chains on the size of the hollow polymeric micelles.The result showed that with grafting level increasing

the size of these nanoparticles diminished accordingly.Moreover

critical micelle concentration (CMC) was determined based on I3/I1 derived from emission spectrum afforded by fluorescence spectroscopy with pyrene as fluorescent probe

with the value of CMC 2.03210-2mg/mL.At last

the optical properties of OPEGC/QDs were characterized by UV-Vis spectroscopy

fluorescence spectroscopy and the morphology of their assembly formed in water was observed by TEM.The results indicated that the OPEGC/QDs nanoparticles with narrow size distribution were prepared here

which represented good water solubility and high quantum yield.