银纳米链状材料的制备及近红外吸收性质

报道了利用水/油相界面反应,采用湿化学法合成银纳米链状材料的方法,并对这种材料的近红外吸收性质和光热转换性质进行了研究。TEM分析表明,银纳米材料为链状结构,直径约为50nm,长度分布范围较宽,从几十纳米至几百纳米。这种材料具有强的近红外吸收特性,随着还原剂加入量的增加,吸收带逐渐展宽(800～1300nm),而且平坦。这种材料具有优异光热转换性质,一经808nm激光照射,温度迅速提高。该材料优异的近红外吸收和光热转换性质,使其在红外断层成像和近红外热疗等领域具有广阔的应用前景。

Synthesis of Ag Nanochains and Near-infrared Absorption Property

Halas and her co-workers reported the gold nanoshells,with strong surface plasma resonance(SPR)absorption band in near-infrared(NIR)region of 800~1 200 nm,the transparent window of biological tissues.This kind of gold nanoshells was successfully used in thermal ablative therapy for cancer by NIR photo-thermal conversion.The noble metal nanomaterials with strong NIR absorption are also an ideal candidate for diffuse optical tomography,which is a promising imaging modality for early detection of diseases.Silver nanomatertials,as the metal with the highest electrical and thermal conductivity,if their SPR absorption were extended to NIR region,should have more excellent photothermal conversion property.One-dimensional silver nanomaterials,such as silver nanowires or wire-like nanostructures,have both transverse and longitudinal SPR absorption modes.The absorption location for the transverse SPR mode is fixed at ~ 400 nm,while that of the longitudinal SPR mode varies depending on the ratio of length to width of the nanostructures.Therefore,if the ratios of length to width of the silver nanowires are modified,then the longitudinal SPR absorption should be broaden inhomogeneously and may extended to NIR region.In this work,cross-sectional Ag nanochains with diameters of 10~30 nm were prepared using the method of water/oil emulsion.This kind of Ag nanochains demonstrated strong and super-wide SPR absorption extending from 400 to 1 200 nm.It exhibited better photothermal conversion property than that of the well-known gold nanoshells,and thus is more suitable to be used in biomedicine as the photothermal converters and in diffuses optical tomography as the contrast agent.