Hybridizing Silver Nanoparticles in Hydrogel for High-Performance Flexible SERS Chips

Abstract

An ideal surface-enhanced Raman scattering (SERS) substrate should have high sensitivity, long-term stability, excellent repeatability, and strong anti-interference. In the present work, single-layer carbon-based dot (CD)-capped Ag nanoparticle aggregates (a-AgNPs/CDs) with high SERS activity are synthesized and hybridized with a hydrogel to prepare novel hydrogel SERS chips. Benefiting from the unique properties of a-AgNPs/CDs and the hydrogel, the constructed hydrogel SERS chips show excellent performances. Taking crystal violet detection as an example, the hydrogel SERS chips show a detection limit of around 1 × 10–16 mol/L (high sensitivity), maintain above 96.40% of SERS activity even after 14 weeks of storage (long-term stability), and display point-to-point relative standard deviation (RSD) in one chip as low as 1.43% (outstanding repeatability) and RSD in different chips as low as 2.75% (excellent reproducibility). Furthermore, the self-extraction effect of the hydrogel enables the flexible hydrogel SERS chips to be used for analyzing various real samples including soybean milk, juices, and fruits without any complex pretreatment. For instance, the hydrogel SERS chips are able to detect trace thiram and 2-(4-thiazolyl)­benzimidazole with the detection limits of 1 and 5 ppb in liquid samples, respectively, and of 1 and 2.5 ng/cm2 on the peel of fruits, respectively. The self-extraction functional flexible SERS chips offer a reliable and convenient platform for the quick detection and on-site monitoring of chemical contaminants.

High‐Performance Hydrogel SERS Chips with Tunable Localized Surface Plasmon Resonance for Coordinated Electromagnetic Enhancement with Chemical Enhancement

“…Our recent investigation has proved that hydrogel SERS chips could be well applied in the detection of pesticide residues in actual samples, without any obvious interference from sample matrix. [30] However, the sample matrix for veterinary drug residues is usually much complex than that for pesticide residues. [40][41][42] Herein, the applicability of the obtained hydrogel SERS chip is further evaluated by detecting amoxicillin in pork.…”

“…As shown in Figure a, a simple Ca 2+ ‐mediated assembly of AgNPs is applied for the in situ formation of a‐AgNPs in the PVA solution, which is followed by a physical cross‐linking possess to prepare hydrogel SERS chips. [ 30 ] The LSPR wavelength of the obtained a‐AgNPs can be easily tuned by controlling the amount of added Ca 2+ . Thus, hydrogel SERS chips suitable for three commonly used laser wavelengths (532, 633, and 785 nm) can be finally constructed.…”

“…On the other hand, the hydrogel can effectively avoid creating a “coffee ring” during testing. [ 30 ] Third, the long‐term stabilities of the three chips were assessed by measuring the SERS spectrum of ATP every 15 d over a 90‐d storage period. It is found that the SERS spectrum of 4‐ATP has no obvious change during the long‐term investigation.…”

Ag/Poly(N-isopropylacrylamide)-laponite Hydrogel Surface-Enhanced Raman Membrane Substrate for Rapid Separation, Concentration and Detection of Hydrophilic Compounds in Complex Sample All-in-One

“…28,29 In recent years, hydrogel particles have been developed for highly selective and sensitive detection of complex samples. 30 Hydrogel particles are obtained by loading monomers or oligomers with a small amount of a photoinitiator in the dispersed phase and polymerizing them under UV irradiation. 31 The prepared microparticles are characterized by uniform particle size, controlled pore size, and good monodispersity.…”

Dual signal magnification for ultrasensitive biosensing based on well-regulated SERS of AuNTs@AuHg and DSN-assisted amplification

“…11 The characteristic of susceptibility to aggregation might lead to a prominently negative influence on SERS activity. 12,13 Thereby, improving SERS performance and anti-aggregation of metal substrates remains a major challenge for biosensing applications. In our work, the surface electrostatic repulsion of metal NPs was enhanced to prevent aggregation via surface modification of AuHg on gold nanotriangles (AuNTs), resulting in the improvement of the anti-aggregation stability of AuNTs@AuHg, which was beneficial for the construction of a stable and ultrasensitive biosensing platform.…”