Multifunctional polymer drug loading system with pH-sensitive, fluorescent and targeting property.

IA multifunctional drug loading system with pH-sensitive, fluorescent and targeting property was fabricated. Firstly, the amphipathic N-octyl-N'-(2-carboxyl-cyclohexamethenyl) chitosan (OCCC) was prepared by grafting hydrophobic octyl group and hydrophilic hexahydrophthalic anhydride onto chitosan, then it was modified with folic acid (FA) and thiazole orange (TO) using polyethylene glycol (PEG) as the link to fabricate a multifunctional drug loading system TO-PEG-OCCC-PEG-FA. Its chemical structure was determined by Fourier transform infrared spectroscopy (FT-IR), elemental analysis, differential scanning calorimetry (DSC) analysis, UV-vis and fluorescence spectrometer, and the results showed that the substitution degree of hydrophobic/hydrophilic group onto chitosan were 41.4% and 59.1% respectively. The FA and TO were successfully grafted onto chitosan using PEG as link, and their grafting degree were 5.1% and 0.216% respectively. The fabricated multifunctional chitosan micelle with a concentration of 10mg/mL showed a 42.76% encapsulation efficiency on 5-fluorouracil, and it was stable under physiological pH (pH=7.4), but showed an excellent pH-sensitive drug release property under acid environment (pH=4.0). Additionally, the drug release amount could reach up to 95% during 4h.

The fluorescent interactions between amphiphilic chitosan derivatives and water-soluble quantum dots.

The LCC-CdTe quantum dots (QDs) hybrid was fabricated by mixing the N-lauryl-N, O-carboxymethyl chitosan (LCC) micelle with water-soluble CdTe QDs in an aqueous solution via hydrophobic forces and the electronic attraction. The structures of LCC and LCC-CdTe QDs hybrid were determined by differential scanning calorimetry (DSC), Fourier transform infrared (FT-IR) spectroscopy and transmission electron microscopy (TEM). The results showed that the lauryl and carboxymethyl were successfully grafted to chitosan oligosaccharide (CSO), and a number of CdTe QDs were encapsulated by LCC micelle to form a core/shell structure. The tested results of the fluorescent characteristics of LCC, CdTe QDs and LCC-CdTe QDs hybrid showed that there were some obvious fluorescent interactions between LCC and CdTe QDs. Meanwhile, with the change in LCC space structure, the fluorescent interactions between LCC and QDs showed different fluorescent characteristics. The QDs fluorescent (FL) intensity increased first and then decreased to almost quenching, while LCC FL intensity decreased continually.