New Surface-Enhanced Raman Sensing Chip Designed for On-Site Detection of Active Ricin in Complex Matrices Based on Specific Depurination

• Published in: ACS applied materials & interfaces 2016-01, Vol.8 (3), p.2449-2455
• Main Authors: Tang, Ji-jun, Sun, Jie-fang, Lui, Rui, Zhang, Zong-mian, Liu, Jing-fu, Xie, Jian-wei
• Format: Article
• Language: English
• Subjects: Gold - chemistry; Nanoparticles - chemistry; Nanoparticles - ultrastructure; Oligodeoxyribonucleotides - chemistry; Purines - chemistry; Ricin - analysis; Spectrophotometry, Ultraviolet; Spectrum Analysis, Raman - methods
• ISSN: 1944-8244; 1944-8252
• DOI: 10.1021/acsami.5b12860

Quick and accurate on-site detection of active ricin has very important realistic significance in view of national security and defense. In this paper, optimized single-stranded oligodeoxynucleotides named poly­(21dA), which function as a depurination substrate of active ricin, were screened and chemically attached on gold nanoparticles (AuNPs, ∼100 nm) via the Au–S bond [poly­(21dA)–AuNPs]. Subsequently, poly­(21dA)–AuNPs were assembled on a dihydrogen lipoic-acid-modified Si wafer (SH–Si), thus forming the specific surface-enhanced Raman spectroscopy (SERS) chip [poly­(21dA)–AuNPs@SH–Si] for depurination of active ricin. Under optimized conditions, active ricin could specifically hydrolyze multiple adenines from poly­(21dA) on the chip. This depurination-induced composition change could be conveniently monitored by measuring the distinct attenuation of the SERS signature corresponding to adenine. To improve sensitivity of this method, a silver nanoshell was deposited on post-reacted poly­(21dA)–AuNPs, which lowered the limit of detection to 8.9 ng mL–1. The utility of this well-controlled SERS chip was successfully demonstrated in food and biological matrices spiked with different concentrations of active ricin, thus showing to be very promising assay for reliable and rapid on-site detection of active ricin.