Ag Nanoparticles Decorated Cactus-Like Ag Dendrites/Si Nanoneedles as Highly Efficient 3D Surface-Enhanced Raman Scattering Substrates toward Sensitive Sensing

Abstract

Surface-enhanced Raman scattering (SERS) has been considered as a promising sensing technique to detect low-level analytes. However, its practical application was hindered owing to the lack of uniform SERS substrates for ultrasensitive and reproducible assay. Herein, inspired by the natural cactus structure, we developed a cactus-like 3D nanostructure with uniform and high-density hotspots for highly efficient SERS sensing by both grafting the silicon nanoneedles onto Ag dendrites and subsequent decoration with Ag nanoparticles. The hierarchical scaffolds and high-density hotspots throughout the whole substrate result in great amplification of SERS signal. A high Raman enhancement factor of crystal violet up to 6.6 × 10(7) was achieved. Using malachite green (MG) as a model target, the fabricated SERS substrates exhibited good reproducibility (RSD ∼ 9.3%) and pushed the detection limit down to 10(-13) M with a wide linear range of 10(-12) M to 10(-7) M. Excellent selectivity was also demonstrated by facilely distinguishing MG from its derivative, some organics, and coexistent metal ions. Finally, the practicality and reliability of the 3D SERS substrates were confirmed by the quantitative analysis of spiked MG in environmental water with high recoveries (91.2% to 109.6%). By virtue of the excellent performance (good reproducibility, high sensitivity, and selectivity), the cactus-like 3D SERS substrate has great potential to become a versatile sensing platform in environmental monitoring, food safety, and medical diagnostics.

Nanosilicon-Based Composites for (Bio)sensing Applications: Current Status, Advantages, and Perspectives

“…Therefore, different nano-Si/metal nanocomposites (MNps) have been widely employed for rationally designing and fabricating high-performance (bio)sensors for the detection of various chemical and biological species [144]. The deposition of metal nanoparticles/nanofilms over all types of nano-Si can be implemented by the following techniques: (i) magnetron sputtering [31,51,145,146,147,148,149]; (ii) immersion, chemical, and electrochemical depositions [13,20,27,150,151,152,153,154,155,156,157,158,159,160,161,162,163,164,165,166,167,168,169,170]; (iii) thermal evaporation [32,44,171,172,173,174,175,176,177,178,179]; and (vi) laser ablation technique/pulsed laser deposition [180,181].…”

“…Nowadays, nano-Si/MNps nanocomposites have been utilized for (bio)sensors based on SERS [12,20,31,32,51,145,149,150,151,152,153,154,155,165,168,173,175,176,177,178,182,183,184], optical [13,44,158,164,167,171,180], and electrical [27,146,148,156,159,160,161,162,166,169,170,172,173,179,181,185,186] responses. Among all of these approaches, SERS of MNps decorated nano-Si is extensively exploited as the most efficient spectroscopic phenomenon for high-sensitive sensing.…”

“…In order to obtain a high-sensitive SERS–active platform, the authors in [20] proposed a multi-step fabrication process including the following steps: (i) fabrication of Ag dendrites; (ii) AuNPs deposition over Ag dendrites; (iii) synthesis of Si nanoneedles; and (iv) nanoneedle decoration by AgNPs. The authors noted that such 3D multi-structures were fabricated to achieve a much stronger enhancement when compared with the SERS-active AgNPs or 1DAg dendrites.…”

“…Nowadays, sensors and biosensors based on nano-Si have been successfully applied to molecules [15], biomolecules [16] and light [17] detection using different responses (PL [18,19], SERS [20], I–V [21], reflectance [22,23], resistance [24], capacitance [25], fluorescence [26]) and material modifications (PSi, SiNWs, SiNPs). Such strong interest in (bio)sensors based on nano-Si can be explained by their enhanced surface to volume ratio, biocompatibility, and low-cost.…”

Three-dimensional porous SERS powder for sensitive liquid and gas detections fabricated by engineering dense “hot spots” on silica aerogel

“…One is to assemble the metallic nanostructures layer by layer at liquid-liquid or liquid-air interface. [34][35][36] The other is to assemble/synthesize the nanoparticles directly on a 3D scaffold, such as the butterfly wings, 37 metal-organic frameworks, 38 filter paper, 39 graphene foam 40 and some hierarchical structures, [41][42][43][44] etc. These 3D SERS substrates with high density of "hot spots" in three dimensions, large surface area and tolerance in focus mis-alignment, have demonstrated great improvements on both the sensitivity and homogeneity.…”