Their losses remained relatively steady after 10 cycles. The total losses after 50 cycles wereabout 10% in water and about 11% in a detergent solution. It is also noticed that the position of the surface plasmon resonance peak (λmax) shifted after washing (insets of panels A and B of Figure 4). Figure 4D shows the plots of λmax as a function of the laundering cycle. After washing in water, λmax increased to 422 nm after 5 cycles, indicating some particle aggregation on the fiber surface. In a detergent solution, λmax increased to 424 nm after 10 cycles and remained steady for further washing.The greater increase of λmax in a detergent solution than in water suggests that the detergent facilitated the particle aggregation into larger particles.