In situ preparation of gold nanospheres in bead composed of alginate/poly(N-isopropylacrylamide-co-dimethyl aminoethyl methacrylate) and photothermal controlled release

초록

Near-infrared (NIR)-responsive beads were developed by reducing gold ions electrostatically captured in the bead matrix composed of alginate and poly(N-isopropylacrylamide-co-dimethyl aminoethyl methacrylate) (PNIPAM-DMAEMA). PNIPAM-DMAEMAs (95/5 and 85/15, molar ratio) were included as a thermo-responsive polymer. The beads were prepared by dropping mixture solution of alginate/PNIPAM-DMAEMA (0.6 % (w/v)/2.4 % (w/v)) into gold ions solution (100 mM). The gold ions in the bead matrix could be converted to gold nanosphere (10-13 nm in diameter) using sodium citrate as a reducing agent. The SEM-EDS revealed that gold nanospheres were dispersed in the bead matrix. The content of gold nanosphere in alginate/PNIPAM-DMAEMA (95/5) bead and PNIPAM-DMAEMA (85/15) bead, evaluated spectrophotometrically, was 3.19 and 0.91 %, respectively. The bead suspensions (1 %, w/v) were readily heated over 40 A degrees C in 5 min upon NIR (808 nm, 2 W) irradiation. The release of FITC-dextran from PNIPAM-DMAEMA beads was significantly promoted by the irradiation. Due to the heat generated by the surface plasmon resonance of the gold nanospheres, the thermo-responsive polymer would undergo a thermal contraction and the pores of the bead matrix might be widened, leading to a facilitated release.

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