Development and Biomedical Application of Non-Noble Metal Nanomaterials in SERS

Abstract

Surface-enhanced Raman scattering (SERS) is vital in many fields because of its high sensitivity, fast response, and fingerprint effect. The surface-enhanced Raman mechanisms are generally electromagnetic enhancement (EM), which is mainly based on noble metals (Au, Ag, etc.), and chemical enhancement (CM). With more and more studies on CM mechanism in recent years, non-noble metal nanomaterial SERS substrates gradually became widely researched and applied due to their superior economy, stability, selectivity, and biocompatibility compared to noble metal. In addition, non-noble metal substrates also provide an ideal new platform for SERS technology to probe the mechanism of biomolecules. In this paper, we review the applications of non-noble metal nanomaterials in SERS detection for biomedical engineering in recent years. Firstly, we introduce the development of some more common non-noble metal SERS substrates and discuss their properties and enhancement mechanisms. Subsequently, we focus on the progress of the application of SERS detection of non-noble metal nanomaterials, such as analysis of biomarkers and the detection of some contaminants. Finally, we look forward to the future research process of non-noble metal substrate nanomaterials for biomedicine, which may draw more attention to the biosensor applications of non-noble metal nanomaterial-based SERS substrates.

Keywords: biomedical marker detection; enhancement factor; non-noble metals; surface-enhanced Raman scattering.

Figure 2

(a) Curves of g-band Raman intensity (blue) and P3 peak of R6G (red) with the number of layers of graphene oxide flakes [19]. (b) The schematic of GERS molecular selectivity shows different types of M1, M2, M3, and M4 [22]. (c) HRTEM and STM images of NG after transfer and typical STM images of NG sheets synthesized with different doping parameters [25]. The triangles and the circles here indicate the STM double N substitution configuration, and the arrow indicates the STM single N substitution. (d) SEM image of graphdiyne hollow microspheres [29]. (e) Schematic of the 3D structure of three-layer silver nanoparticles [33].

Figure 3

(a) Flower-like Cu₂O@Ag TEM image [42]. (b) Typical SEM image of Ag NVs/Cu₂O heterostructure [44]. (c) Substrate rinsed with ethanol 3 times at room temperature, after Ar/O₂ mixed plasma treatment for 5 s × 5 times, and for 10 s × 5 times [46]. (d) The linearity of the logarithm of the 1390 cm⁻¹ peak intensity versus the logarithm of the MO concentration and the error bars indicate standard deviation [49]. (e) Self-assembly of Cu₂O nanoarrays with nanogap tuning and Raman enhancement mechanism [50]. (f) Schematic of the working principle of the respiratory RNA virus-sensing platform based on Cu₂O NAs [50].

Figure 4

(a) Raman spectra of R6G molecules deposited on MoO₂ substrates after immersion in different concentration solutions [53]. (b) Proposed synergistic plasmon enhancement mechanism for Mo/MoO₂ hybridized SERS substrates [55]. (c) Schematic diagram of one-step synthesis of molybdenum disulfide and WS₂ using metal foil [57]. (d) Schematic of MoS₂ and MSOR₁ nanoparticle synthesis pathways with different structures [64]. (e) Raman spectra of MoS₂, MSOR_0.5, MSOR₁, and MSOR_1.5 [64].

Figure 5

(a) Schematic structure of WO₃ and W₁₈O₄₉ [66]. (b) UV-vis spectra of H₂ annealed Al-based and Si-based WO_3−x films [67]. (c) Atomic modeling diagram of Vo randomly distributed WO_3−x [69]. (d) Schematic diagram of one-dimensional oriented WO_3−x nanowires synthesized from two-dimensional WSe₂ flakes by oxygen plasma treatment [76]. (e) The electronic structure of WC_0.82 was obtained by DFT simulation [77].

Figure 6

(a) E-SERS performance and composition of functional substrate layers [81]. (b) XPS spectra of monolayer Ti₃C₂T_x nanosheets under microwave heating [84]. (c) Schematic EF curves of the enhanced Raman mechanism of Ti₃C₂T_x nanosheets [85]. (d) AFM image of TiVC nanosheets [90]. (e) Schematic SERS enhancement of Nb₂C-Au NPs [92]. (f) Simulated electric field distribution and local multiplicity on solid spheres of Ti₃C₂-Ag NPs [93].

Figure 11

(a) Schematic diagram for detecting mixtures of multiple VOCs [152]. (b) Schematic diagram of the SERS biosensor for Pb²⁺ detection [156]. (c) Schematic diagram of the formation mechanism of GDY HSs [28]. (d) Schematic diagram of Ag-TiO₂ nanosubstrate for SERS detection [161]. (e) Schematic of charge transfer mechanism between organic pollutants and MoS₂ nanoflower photocatalysts under sunlight [162]. (f) Schematic of SERS mechanism of ENR on TiO₂/ZnO heterojunction [165].

Figure 1

Overview of the development of non-noble metal nanomaterials in SERS.

Figure 7

(a) Formation of ZnO-based semiconductor quantum probes for SERS and nano dendrimer platforms for cell adhesion using femtosecond laser interaction [108]. (b) Schematic of the MGT substrate’s synthesis process and enhancement mechanism [109]. (c) Mechanism of action of dual-targeted SERS cell sensors [111].

Figure 8

(a) Schematic diagram of the synthesis and application of Ag/BP-NS SERS sensor [99]. (b) Fabrication of MoS₂-based aptasensor for exosome detection [113]. (c) Schematic diagram of the Au@Ag NPs/GO) biosensor [114]. (d) Principle of the Au@Raman Reporter@PtOs-driven LFA for catalytic colorimetric, SERS, and photothermal signal detection of breast cancer exosomes [115].

Figure 9

(a) TEM images and Raman spectra of NGO-GNPCs [128]. (b) Schematic energy band diagram of the charge transfer process in the ternary system of R6G, MoS₂ nanoflowers, and nanosheets [129]. (c) Schematic illustration of significant steps involved in the synthesis of SiO₂@Au-Ag Janus CJS [130].

Figure 10

(a) Schematic diagram of synthesized GSP@ZIF-8 core–shell structure and SERS detection [131]. (b) Raman spectra of the glyoxal, glutaraldehyde, benzaldehyde, and phenylacetaldehyde at the concentrations of 1.0 ppb [133]. (c) Schematic of the structure of the LR-SERS substrate [136]. (d) Photographs of Fe₃O₄@Au-based SERS strips and corresponding SERS mapping images of three T lines for different concentrations of H1N1, SARS-CoV-2, and RSV [137].