Precise modulation of gold nanorods aspect ratio based on localized surface plasmon resonance

• Effect of H2O2 oxidation on GNRs was detailedly investigated.
• A linear relationship was demonstrated between oxidation time and GNRs aspect ratio.
• GNRs aspect ratios could be simply modulated by adjusting H2O2 oxidation time. The average error of modulation is 2.92%.
• Increase in temperature (from 30 °C to 60 °C) or solution acidity (pH from 2.6 to 1.2) facilitates the oxidation process.

Gold nanorods (GNRs) aspect ratio is significant to GNRs-based biomedical sensors. In this paper precise modulation of GNRs aspect ratio was realized by H2O2 oxidation based on localized surface plasmon resonance (LSPR) of GNRs. The oxidation process was studied in detail. A linear relationship was revealed between H2O2 oxidation time and the longitudinal LSPR wavelength of GNR, the latter depending on GNRs aspect ratio. Using the relationship GNRs aspect ratios could be modulated by H2O2 oxidation time. Oxidation time deduced aspect ratio was verified by transmission electron microscope (TEM) characterization and the average error is 2.92%. Influences of temperature and pH value on the modulation process were investigated. Increase in temperature (from 30 °C to 60 °C) or solution acidity (pH value from 2.6 to 1.2) facilitated the oxidation process. The proposed method is characterized by its simplicity and efficiency, and would find extensive application prospects in GNRs-based biomedical sensing fields.