Tuning of the near-infrared localized surface plasmon resonance of Cu2-xSe nanoparticles with lysozyme-induced selective aggregation

In this paper, negatively charged Cu2-xSe nanoparticles (NPs), stabilized by poly(styrene sulfonic acid) sodium (PSS) (PSS-Cu2-xSe NPs), were synthesized via a simple templated method, which exhibited strong localized surface plasmon resonance (LSPR) absorption in the near-infrared (NIR) region. It was found that the prepared PSS-Cu2-xSe NPs could be aggregated by lysozymes (Lys) selectively through the electrostatic interaction, since the Lys was positively charged in a neutral medium, producing a red shift of the LSPR band starting from 980 nm to 1300 nm area. With different concentrations of Lys, the LSPR band can be dynamically tuned, and the absorbance ratio of A(1300)/A(980) has a good linear relationship with the concentration of Lys in the range of 5-100 nM, thus supplying an effective way to tune LSPR in the NIR region of semiconductors that might be applied for sensing and photothermal conversion sciences and technologies in the NIR region.