Thermo-responsive Gold Nanospheres As Non-covalent Drug Carriers

In this article, polymer modified gold nanospheres with photo and thermal dualresponsive abilities had been synthesized and applied as the controlled release drugcarrier. Firstly, Poly(N-isopropylacrylamide)(PNIPAM)was synthesized by freeradical polymerization in water using azobisisobutyronitrile as initiator, andmercaptoacetic acid as chain transfer agent. The low generation polyamidoamine(PAMAM) dendrimers were synthesizedby repeated Michael addition reaction andamidation reaction, using ethylenediamine and methyl acrylate as starting materials.Secondly, PNIPAM was grafted onto the PAMAM.Finally, PNIPAM-PAMAMmodified gold nanosphere was synthesized via in-situ method and systematicallyresearch on it was carried out.1H NMR and GPC were used for characterizing the PNIPAM-PAMAM. Itshowed that the polymer had been synthesized successfully and the molecular weightwas about8600g/mol. The lower critical solution temperature (LCST) of thePNIPAM-PAMAM measured by UV-Vis was33.5oC. Transmission electronicmicroscopy (TEM) was used for determining the core size of the PNIPAM-PAMAMmodified gold nanospheres. Results showed that the size of the gold colloid was lessthan10nm, thus it is applicable for drug carrier. Surface Plasmon Resonance (SPR)was carried out with UV-Vis spectrum, and the results were:541nm and532nm,respectively for two different gold nanospheres, which confirmed that the gold coreexisted stably. The LCST of the PNIPAM-PAMAM modified gold nanospheres wasmeasured by UV-Vis spectrum and the results were38.2oC and40.3oC, respectively.Laser was used for measuring the photo-thermal properties of the PNIPAM-PAMAMmodified gold nanospheres. The results indicated that the PNIPAM-PAMAMmodified gold nanospheres are better drug carriers than the PNIPAM-PAMAMpolymer alone.