SERS-active metal–organic frameworks with embedded gold nanoparticles

Abstract

Surface-enhanced Raman scattering (SERS) has been widely used in the detection of targets and strongly depends on the interaction and the distance between the targets and nanoparticles. Herein, metal-organic frameworks (MOFs) were first easily synthesized on a large scale via a water bath method, especially Uio-66 and Uio-67. MOFs embedded with gold nanoparticles (AuNPs) for SERS enhancement were successfully fabricated via an impregnation strategy. The synthesized AuNPs/MOF-199, AuNPs/Uio-66, and AuNPs/Uio-67 composites, with LSPR properties and high adsorption capability of MOFs to preconcentrate the analytes close to the surface of the AuNPs, exhibited excellent SERS activity. The effects of the reducing concentrations of sodium citrate on the SERS activity, and the stability and reproducibility of the AuNP/MOFs have been discussed via the detection of acetamiprid. The SERS intensity enhanced by the composites was retained for more than 40 days under ambient conditions with the reducing concentrations of sodium citrate at 0.16%, 0.20%, and 0.16%. The limits of detection with the signal/noise ratio higher than 3 at the characteristic peak 632 cm were 0.02 μM, 0.009 μM, and 0.02 μM for acetamiprid. Most interestingly, the AuNP/MOF-199 composites, whose morphology was long tube sheet, exhibited excellent SERS activity. These novel composites with high sensitivity, stability, and reproducibility provide a new route for the detection of pesticides via the SERS technology.

Understanding the Role of Metal–Organic Frameworks in Surface‐Enhanced Raman Scattering Application

“…Increasingly serious food safety problems and environmental pollution crisis have attracted people's attention, which seriously threatened the ecological environment and human health. MOF‐based SERS substrates have been successfully used to detect pesticide residues, [ 58 ] illegal additives, [ 29 ] and environmental pollutants. [ 28 ] Cao et al.…”

A Simple SERS-Based Trace Sensing Platform Enabled by AuNPs-Analyte/AuNPs Double-Decker Structure on Wax-Coated Hydrophobic Surface

“…Furthermore, excellent size and shape tunability of AuNPs make it possible to optimize the enhancement factor for desired SERS detection. To date, scores of reports have been published on AuNPs-based SERS for the detection and discrimination of DNA (Lim et al, 2010 ), anticancer drugs (Ilkhani et al, 2016 ; Kurzatkowska et al, 2017 ), amino acid (Schwartzberg et al, 2004 ), melamine (Lee et al, 2007 ; He et al, 2011 ; Kim et al, 2012 ; Giovannozzi et al, 2014 ; Rajapandiyan et al, 2015 ), biothiols (Liu et al, 2017 ), various pesticides (Nguyen et al, 2014 ; Alsammarraie and Lin, 2017 ; Cao et al, 2017 ; Fortuni et al, 2017 ; Jiang et al, 2017 ; Tan et al, 2017 ), and other hazardous chemicals (Li et al, 2011 ). For example, Giovannozzi et al ( 2014 ) presented a simple AuNPs based SERS system in aqueous solution for melamine detection, in which colloidal AuNPs displayed satisfactory SERS enhancement with a limit of detection of 1.35 μM melamine.…”

Estudo de compósito formado por nanopartículas de ouro em matriz polimérica como substratos para análise SERS.

“…Assim, considerando que as nanopartículas expostas tomem um formato de meia-esferas, devem existir regiões de alta concentração de campo elétrico (hot-spots) [10,11] que favorecem o efeito SERS. No entanto, a intensificação do sinal SERS já foi observada em substratos contendo uma camada de material isolante envolvendo as nanopartículas [6][7][8][71][72][73][74], o que corrobora nossos resultados. O experimento para analisar o efeito da revelação do PMMA após a implantação de ouro foi repetido, mas utilizando-se um método diferente para a deposição do analito R6G sobre os substratos.…”

“…Tendo isto em vista, um dos principais desafios no sensoriamento químico e biológico se encontra na detecção de traços de uma dada substância (analito), podendo chegar idealmente ao regime de detecção de uma única molécula. Uma forma possível de se obter esta detecção é por meio de medidas por SERS (Surface-Enhanced Raman Spectroscopy) utilizando substratos contendo nanoestruturas metálicas [4][5][6][7][8], no caso deste trabalho, nanopartículas de ouro (AuNPs) formadas abaixo da superfície do polimetilmetacrilato (PMMA). Esta abordagem permite a formação de nanopartículas no interior do substrato e com a vantagem de protegê-las do meio ambiente, garantindo a estabilidade da camada compósita [9,10].…”

“…É conhecido que outros metais como prata e cobre também podem ser utilizados para a fabricação de substratos SERS, porém, a dificuldade em utilizar estes materiais é a sua reatividade, em especial, com oxigênio [4][5][6][7][8]. Neste contexto, a abordagem utilizada neste trabalho permite a formação de nanopartículas isoladas no interior de um substrato de PMMA, de forma que o metal fique protegido do meio ambiente, garantindo a estabilidade da camada compósita.…”