Department of Nanophysics, Istituto Italiano di Tecnologia, Via Morego 30, I-16163 Genova, Italy.
Nanotechnology. 2017 Oct 13;28(41):415601. doi: 10.1088/1361-6528/aa8337. Epub 2017 Aug 1.
The localized formation of gold nanostructures with controlled size and shape on chitosan films doped with gold precursor upon electromagnetic irradiation of various types is demonstrated here. Such controlled formation is achieved by tuning the wavelength, the energy and the interaction time of the radiation with the composite films. In particular, the use of a single UV nanosecond laser pulse results in the formation of gold sub-micron platelets with specific crystal structure, while increasing the number of pulses, further precursor reduction and photofragmentation induce the formation of gold nanoparticles. Using x-ray radiation as an alternative energy source, the reduction of the gold precursor and the subsequent formation of particles follow a different pathway. Specifically, x-ray-induced photo-reduction triggers the selective formation of gold sub-micron platelets with a very well defined {111} crystal phase. In this case, the density of crystal platelets increases by increasing the irradiation time of the films, while no photofragmentation process is observed. The gold structures pre-formed by x-ray radiation can be fragmented by subsequent pulsed UV laser irradiation forming nanoparticles with much narrower size distribution compared to that obtained via exclusive UV irradiation. Thanks to the perfect coupling between the natural polymeric matrix and gold nanostructures, the bionanocomposite systems developed could find various applications in biomaterial science and in biosensors field.
本文展示了在掺杂金前体的壳聚糖膜上，通过电磁辐射（包括不同类型的辐射）在局域形成具有受控尺寸和形状的金纳米结构。通过调整辐射的波长、能量和相互作用时间，可以实现这种受控形成。特别地，使用单个紫外纳秒激光脉冲会导致具有特定晶体结构的金亚微米板的形成，而增加脉冲数量、进一步还原前体和光解则会诱导金纳米颗粒的形成。使用 X 射线作为替代能源，金前体的还原和随后的颗粒形成遵循不同的途径。具体而言，X 射线诱导的光还原会触发具有非常明确的{111}晶体相的金亚微米板的选择性形成。在这种情况下，通过增加膜的辐照时间，可以增加晶体板的密度，而不会观察到光解过程。通过后续的脉冲紫外激光辐照，可以使 X 射线辐照预先形成的金结构发生碎片化，从而形成比仅通过紫外辐照获得的更窄的纳米颗粒尺寸分布。由于天然聚合物基质与金纳米结构之间的完美结合，所开发的生物纳米复合材料系统在生物材料科学和生物传感器领域可能有多种应用。
