Autor(es)

Oliveira, Marcelo J. ; Bianchi-Carvalho, Isabela ; Rubira, Rafael J. ; Sanchez-Cortes, Santiago ; Constantino, Carlos J.

• Tipo de documento: Artigo Científico
• Fonte: ACS OMEGA; v. 9, n. 41, p. 11-pg., 2024-10-02.

Resumo

The level of aggregation and aggregate morphology of metallic nanoparticles are factors that influence the SERS signal (surface-enhanced Raman scattering), affecting reproducibility and sensitivity. This study presents a systematic evaluation of the colloidal aggregation on the SERS signal by combining transmission electron microscopy and UV-vis extinction spectroscopy. It focuses on the effect of two methods of sample preparation ("external standard method-ESM" and "standard addition method-SAM") on the SERS signal using the fungicide thiabendazole (TBZ) in Ag colloid as a probe molecule. The TBZ critical concentration (concentration for which SERS reaches the maximum intensity) was 6.0 x 10(-6) mol/L for ESM and 1.5 x 10(-6) mol/L for SAM. Besides, TBZ exhibited a sigmoid-type isotherm for ESM, indicating formation of a TBZ first layer on Ag nanoparticles at lower concentrations (Ag aggregates more compact; size <500 nm) and TBZ multilayers at higher concentrations (Ag aggregates more branched; >2 mu m). For SAM, the TBZ first layer formation was also observed at lower concentrations (Ag aggregates more branched; <2 mu m). However, at higher concentrations, the Ag colloid degradation/precipitation was observed (Ag aggregates more compact; >2 mu m). The Ag aggregation mechanisms align with reaction-limited colloidal aggregation at lower concentrations and diffusion-limited colloidal aggregation at higher concentrations. We believe these results contribute to the SERS research field despite all of the work already done over its 50-year history. (AU)

• Processo FAPESP: 18/22214-6 - Rumo à convergência de tecnologias: de sensores e biossensores à visualização de informação e aprendizado de máquina para análise de dados em diagnóstico clínico
• Beneficiário: Osvaldo Novais de Oliveira Junior
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• Processo FAPESP: 23/16725-6 - Desenvolvimento de substratos SERS sustentáveis para remoção e detecção de corantes alimentícios sintéticos em meio aquoso
• Beneficiário: Isabela Bianchi Carvalho
• Modalidade de apoio: Bolsas no Brasil - Doutorado Direto
• Processo FAPESP: 22/09619-2 - Mecanismos de agregação coloidal induzidos por diferentes métodos de preparação de amostras e sua relação com a sensibilidade e reprodutibilidade do SERS
• Beneficiário: Marcelo José dos Santos Oliveira
• Modalidade de apoio: Bolsas no Exterior - Estágio de Pesquisa - Mestrado