Interesting optical variations of the etching of Au Nanobipyramid@Ag Nanorods and its application as a colorful chromogenic substrate for immunoassays

•AuNBP@Ag nanorods with highly uniformity is synthesized. Our investigation reveals that the etching of AuNBP@Ag nanorods results in an interesting color variations: the LSPR peak would initially blue shift, and then red shift, and finally blue shift again.•The etching of AuNBP@Ag nanorods was utili...

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