Recent Advances in Metal Organic Frameworks Based Surface Enhanced Raman Scattering Substrates: Synthesis and Applications.

Guoliang Li,Yan Sun,Ying Xu,Panxue Wang,Xiang Li,Li Wang

doi:10.3390/molecules26010209

Abstract

Metal-organic frameworks (MOFs) are supramolecular nanomaterials, in which metal ions or clusters are connected by organic ligands to form crystalline lattices with highly ordered periodic porous network structure. MOFs have been widely applied in various fields, such as catalyst, sample preparation, and sensing. In recent years, MOFs based surface enhanced Raman scattering (SERS) substrates have attracted much attention since MOFs can largely improve the performance of metallic SERS substrates toward target enrichment and signal enhancement. MOFs have been exploited in SERS analysis to tackle some challenges that bare metal substrates cannot achieve. Combination of MOFs and SERS improved the sensitivity of traditional SERS analysis and extended the application scope of SERS. With the increasing exploration of MOFs based SERS substrates, there is a great demand to review the advances in these researches. Herein, this review concentrated on summarizing the preparation and applications of MOFs based SERS substrates. Representative researches were discussed to better understand the property of MOFs based SERS substrates. The advantages of MOFs based SERS substrates were highlighted, as well as their limitations. In addition, the challenges, opportunities, and future trends in MOFs based SERS analysis were tentatively discussed.

Highlights

Depending on the position of Surface-enhanced Raman scattering (SERS)-active NPs, composites of SERS-active metal NP and Metal-organic frameworks (MOFs) can be classified into three groups, namely SERS-active NPs embedded MOFs, SERS-active NPs anchored on the surface of MOFs, and SERS-active NP encapsulated in MOFs
SERS substrates with noble metal NPs anchored on the surface of MOFs can be prepared via an in situ synthesis strategy, namely in situ growth of SERS-active metal NPs on the surface of MOFs
The novel SERS substrates with metal NPs anchored on the surface of MOFs have been applied in the detection of illegal colorants, pesticides, and other chemical compounds related to food safety

Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Metal-organic frameworks (MOFs) and composites of MOF and SERS-active metal substrate have been attracting increasing attentions in recent years since these substrates provide additional advantages on stability, target concentration, and selectivity to conventional SERS substrates [17,18]. The diverse structure and post-modification of MOF based substrates provide more options for SERS analysis such as rapid target enrichment [34], molecular selectivity [35,36], and signal conversion [37]. The SERS effect of MOFs was mainly due to the charge transfer effect between the adsorbed molecules and metal oxide clusters in MOFs. In addition, MIL-100 (Fe) has been applied as SERS substrate for the detection of VOCs [39]. MOF materials with SERS activity offer great opportunities to study the chemical enhancement theory of SERS. The SERS effect has only been observed in a few MOFs and efforts are needed to explore more SERS-active MOF materials

Nano-Composites of MOFs and SERS-Active Metal Substrates

Synthesis

Applications

Application

Findings

Conclusions and Future Perspectives