Metal-Modified Montmorillonite as Plasmonic Microstructure for Direct Protein Detection

Abstract

Thanks to its negative surface charge and high swelling behavior, montmorillonite (MMT) has been widely used to design hybrid materials for applications in metal ion adsorption, drug delivery, or antibacterial substrates. The changes in photophysical and photochemical properties observed when fluorophores interact with MMT make these hybrid materials attractive for designing novel optical sensors. Sensor technology is making huge strides forward, achieving high sensitivity and selectivity, but the fabrication of the sensing platform is often time-consuming and requires expensive chemicals and facilities. Here, we synthesized metal-modified MMT particles suitable for the bio-sensing of self-fluorescent biomolecules. The fluorescent enhancement achieved by combining clay minerals and plasmonic effect was exploited to improve the sensitivity of the fluorescence-based detection mechanism. As proof of concept, we showed that the signal of fluorescein isothiocyanate can be harvested by a factor of 60 using silver-modified MMT, while bovine serum albumin was successfully detected at 1.9 µg/mL. Furthermore, we demonstrated the versatility of the proposed hybrid materials by exploiting their plasmonic properties to develop liquid label-free detection systems. Our results on the signal enhancement achieved using metal-modified MMT will allow the development of highly sensitive, easily fabricated, and cost-efficient fluorescent- and plasmonic-based detection methods for biomolecules.

Thioflavin-modified molecularly imprinted hydrogel for fluorescent-based non-enzymatic glucose detection in wound exudate

“…hemoglobin, albumin) and cells absorption peaks in the UV (200–400 ​nm) and UV–Vis (400–700 ​nm) regions but that do not have fluorescent properties. Hence, the analyte should be isolated for biological samples (by centrifugation or alternative techniques [ 59 ]) to be trustfully quantified by colorimetric assay whereas it is not required when using fluorescent-based approaches [ 31 ]. Moreover, the colorimetric assay used as a benchmark in this study is enzymatic-based.…”

“…Moreover, the fabrication of colloidal crystal-based sensors is laborious and SPR analysis requires expensive instrumentation. In this view, fluorescent-based detection approaches are preferential since they are easily designed, simple to measure, cost-efficient, and have been therefore widely exploited for the development of detection systems [ 31 ].…”

Preparation of Laser-Ablated Ag Nanoparticle–MMT Clay-Based Beeswax Antibiofilm Coating

“…L-Ag/MMT showed more intense absorption than that of bare MMT and L-AgNPs in the 240 to 450 nm range. Additionally, a shift towards higher wavelengths was observed that was probably associated with the plasmonic behavior of the interaction of small AgNPs with MMT particles [35][36][37][38]. XPS characterization was carried out to confirm the loading of L-Ag NPs into the MMT matrix.…”

Gold Nanorod Density-Dependent Label-Free Bacteria Sensing on a Flake-like 3D Graphene-Based Device by SERS

“…There are several papers that have shown the improvement in SERS enhancement, introducing several techniques such as the combination of metal-organic frameworks (MOFs) with plasmonic metal nanoparticles [34], silver nanoparticles with porous silicon substrate [35], metal-modified montmorillonite [36], AuNRs functionalized zirconiumbased MOFs [37], and etched-spiky Au@Ag plasmonic superstructures [38]. Our system can analyze bacteria samples without labels using a reusable biosensing device made of graphene and AuNRs.…”