Enhancement of Image Contrast, Stability, and SALDI-MS Detection Sensitivity for Latent Fingerprint Analysis by Tuning the Composition of Silver–Gold Nanoalloys

• Published in: ACS applied materials & interfaces Vol. 8; no. 43; pp. 29668 - 29675
• Main Authors: Cheng, Yu-Hong, Zhang, Yue, Chau, Siu-Leung, Lai, Samuel Kin-Man, Tang, Ho-Wai, Ng, Kwan-Ming
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 02.11.2016
• Subjects: nanoalloys; image stability; silver−gold nanoparticles; latent fingerprints; image contrast; SALDI-MS
• DOI: 10.1021/acsami.6b09668
• ISSN: 1944-8244

Metal alloy nanoparticles (NPs) offer a new combination of unique physicochemical properties based on their pure counterparts, which can facilitate the development of novel analytical methods. Here, we demonstrated that Ag–Au alloy NPs could be utilized for optical and mass spectrometric imaging of latent fingerprints (LFPs) with improved image contrast, stability, and detection sensitivity. Upon deposition of Ag–Au alloy NPs (Ag:Au = 60:40 wt %), ridge regions of the LFP became amber colored, while the groove regions appeared purple-blue. The presence of Au in the Ag–Au alloy NPs suppressed aggregation behavior compared to pure AgNPs, thus improving the stability of the developed LFP images. In addition, the Ag component in the Ag–Au alloy NPs enhanced optical absorption efficiency compared to pure AuNPs, resulting in higher contrast LFP images. Moreover, varying the Ag–Au ratio could enable the tuning of the resulting surface plasmonic resonance absorption and hence affect image contrast. Furthermore, the Ag–Au alloy NPs assisted the surface-assisted laser desorption/ionization MS analysis of chemical and biochemical compounds in LFPs, with better detection sensitivity than either pure AgNPs or AuNPs.