Surface ligand modified silver nanoparticles-based SERS sensing platform for ultrasensitive detection of the pesticide thiram in green tea leaves: roles of coating agents in sensing performance

• Published in: RSC advances 2024-03, Vol.14 (14), p.9975-9984
• Main Authors: Linh, Dong Thi, Mai, Quan-Doan, Nguyet Nga, Dao Thi, Anh, Nguyen Tuan, Van Tuan, Hoang, Nguyen, Ha Anh, Vu, Xuan Hoa, Le, Anh-Tuan
• Format: Article
• Language: English
• Subjects: Chemical synthesis; Chemistry; Coating effects; Electrolytes; Environmental protection; Green tea; Nanoparticles; Oleic acid; Pesticides; Raman spectra; Sensors; Silver; Substrates; Thiram
• ISSN: 2046-2069; 2046-2069
• DOI: 10.1039/d4ra00048j

Silver nanoparticles (AgNPs) have been regarded as a highly promising substrate for surface-enhanced Raman scattering (SERS) sensors. In this study, we focused on the electrochemical synthesis method by developing three kinds of AgNPs using three different electrolytes: citrate (e-Ag-C), oleic acid (e-Ag-O) and fish mint ( Houttuynia cordata Thunb.) extract (e-Ag-bio). The as-prepared AgNPs were characterized and then employed as SERS substrates to detect the pesticide thiram. The obtained results show that e-Ag-O exhibits the best SERS performance. The effect of the coating agent was explained by chemical and electromagnetic enhancements (CM and EM). Although thiram could absorb onto e-Ag-C at the highest level, allowing its Raman signal to be best enhanced via the CM, the smallest interparticle distance of e-Ag-O could have resulted in the largest improvement in the EM. Using e-Ag-O to develop SERS-based sensors for thiram, we obtain the impressive detection limit of 1.04 × 10 −10 M in standard samples and 10 −9 M in tea leaves. The linear ranges are from 10 −4 M to 10 −7 M and from 10 −7 M to 10 −9 M, covering the maximum residue levels for plant commodities established by the United States Environment Protection Agency and European Food Safety Authority (2-13 ppm ∼7.7 × 10 −6 M to 5 × 10 −5 M). We fabricated three AgNPs: Ag-citrate, Ag-oleic, and Ag-bio. All exhibit a SERS effect enhancing thiram's Raman signal. Notably, Ag-Oleic shows superior performance, serving as an active SERS substrate for thiram detection in tea leaves.