Abstract
This experiment applied nanosphere lithography (NSL) to fabricate periodic nanogold arrays by using self-assembly two-dimensional colloidal crystals as the lithographic masks. We have tried two methods to self-assemble1.01μm polystyrene latex colloids. One is spin-coating, which is convenient and inexpensive. Another is “droplet evaporation self-assembling in microwells”, which could control the direction of crystals growth by the meniscus formed during the evaporation process. In the spin-coating part, we increased the monolayer areas by adding solvent alcohol or treating the substrate with O2 plasma before spinning. The biggest single crystal domain we observed in adding alcohol method was only 5μm*5μm, while in O2 plasma treating method was 50μm*50μm. In the droplet evaporation part, the biggest single crystal domain we observed was 250μm*150μm. After finishing the preparation of masks, we deposited 10 nm gold thin films onto the masks by thermal evaporation. Removing the masks and annealing the samples 2 hours in 850℃, we could obtain the densely packed two-dimensional ordered nanoarrays of gold nanospheres. Then we adjusted the angle of thermal evaporation to fabricate different sizes of uniform gold nanospheres arrays from average diameters 135nm to 72 nm. In the last part, we have tried to conjugate the fluorescent proteins on the gold nanostructures and have successively observed the signals by using 100X optical microscopy.