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Label-Free LSPR Detection of Trace Lead(II) Ions in Drinking Water by Synthetic Poly(mPD-co-ASA) Nanoparticles on Gold Nanoislands

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journal contribution
posted on 06.01.2017, 00:00 by Guangyu Qiu, Siu Pang Ng, Xiongyi Liang, Ning Ding, Xiangfeng Chen, Chi-Man Lawrence Wu
Using self-assembly gold nanoislands (SAM-AuNIs) functionalized by poly­(m-phenylenediamine-co-aniline-2-sulfonic acid) (poly­(mPD-co-ASA)) copolymer nanoparticles as specific receptors, a highly sensitive localized surface plasmon resonance (LSPR) optochemical sensor is demonstrated for detection of trace lead cation (Pb­(II)) in drinking water. The copolymer receptor is optimized in three aspects: (1) mole ratio of mPD:ASA monomers, (2) size of copolymer nanoparticles, and (3) surface density of the copolymer. It is shown that the 95:5 (mPD:ASA mole ratio) copolymer with size less than 100 nm exhibits the best Pb­(II)-sensing performance, and the 200 times diluted standard copolymer solution contributes to the most effective functionalization protocol. The resulting poly­(mPD-co-ASA)-functionalized LSPR sensor attains the detection limit to 0.011 ppb toward Pb­(II) in drinking water, and the linear dynamic range covers 0.011 to 5000 ppb (i.e., 6 orders of magnitude). In addition, the sensing system exhibits robust selectivity to Pb­(II) in the presence of other metallic cations as well as common anions. The proposed functional copolymer functionalized on AuNIs is found to provide excellent Pb­(II)-sensing performance using simple LSPR instrumentation for rapid drinking-water inspection.