Composite Materials Based On PH/thermal Responsive Polymer For Drug Release

This article contains two parts.In the first part,a new injectable,carboxymethyl chitosan-functionalized graphene oxide/poly(ethylene glycol)(CMC-rGO/PEG)hydrogels for chemo-photothermal cancer therapy was reported.Reduced graphene oxide improved the near-infrared(NIR)absorbing property of the hydrogels.Meanwhile,the Schiff base linkages,which were formed between aldehyde groups of functionalized PEG and amino groups of CMC,have endowed the hydrogels with injectability and pH-sensitivity.Consequently,the temperature of the hydrogels could be increased from 25 ? to 64 ? upon irradiation with 808 nm laser,suggesting their great potential for photothermal therapy.The utility of these composite hydrogels as drug carriers was also evaluated by encapsulating doxorubicin hydrochloride(i.e.,DOX)within the hydrogel matrix in vitro,and DOX could be released in a faster and more efficient manner under acidic environment than that under physiological environment.That is to say,at pH 7.4,the drug release amount reached about 64%,while the the drug release amount increased up to nearly 100%when the pH is decreased to 6.5.The cell viability assays showed that the CMC-rGO/PEG hydrogel exhibited excellent biocompatibility.Therefore,this hydrogel exhibited injectability,biocompatibility,biodegradation,drug loading capacity and photothermal effect,making it a promising multifunctional platform for chemo-photothermal synergistic cancer therapy.In the second part,novel poly(N-isopropyl acrylamide)/gold clusters(PNIPAM/Au NCs)nanospheres based on thermo-responsive PNIPAM-COOH and fluorescent peptide-Au NCs was fabricated.The hydrophilic-hydrophobic phase transition temperature of PNIPAM-COOH was about 32 ?.A trifunctional peptide was designed to prepare fluorescent peptide-Au NCs by one-step peptide biomineralization method,and the resultant peptide-Au NCs exhibited uniform size distribution,strong red fluorescence and excellent cancer cell target ability.The structure and morphology characterization showed that the composite nanospheres possessed all the excellent properties of two substrates simultaneously.The in vitro drug release experiments showed that 6%and 77%DOX were released form PNIPAM/Au NCs nanospheres at 25 ? and 37 ?,respectively.Moreover,PNIPAM/Au NCs nanospheres possessed excellent biocompatibility and the capability of imaging HeLa tumor cells.It should be noticed that,by taking advantage of excellent stability,thermo-responsiveness,red fluorescence,and targeting ability,the PNIPAM/Au NCs nanospheres are potential nanomaterials for biomedical applications such as controlled release,fluorescence imaging and targeted therapy.