Imprinted Au‐Nanoparticle Composites for the Ultrasensitive Surface Plasmon Resonance Detection of Hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine (RDX)

Abstract

The analysis of explosives attracts recent research efforts due to homeland security needs and the broad demand for the clearance of minefields. While numerous studies have addressed the development of sensing platforms for nitroaromatic explosives, and specifically trinitrotoluene (TNT), the detection of more hazardous explosives, such as hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) or pentaerythritol tetranitrate (PETN), is less developed and needs further efforts, particularly the improvement of the sensitivities associated with the analyses of these substrates.[1,2] Different optical, electrochemical, or microgravimetric sensors or biosensors for TNT were reported. Fluorescent organic polymers, which are quenched by nitroaromatic explosives, [3,4] luminescent polysilole nanoparticles (NPs), [5,6] or fluorescent silicon NPs quenched by nitroaromatic vapors enabled the development of optical sensors. The electrochemical activity of the nitro groups of TNT provided the basis for developing voltammetric sensors for this explosive, [7,8] and recently, a composite of Au NPs linked to electrodes enabled a sensitive electrochemical detection of TNT.[9] Also, different sensing matrices, such as cyclodextrin polymers, [10] carbowax, [11] or silicon polymers, [12] were used for TNT analysis by surface acoustic wave devices, and the aggregation of functionalized Au NPs in the presence of TNT was used to develop an optical sensor for the explosive.[13] Similarly, antibody-based optical [14][15][16] or microgravimetric quartz-crystal-microbalance [17] biosensors for TNT were developed. Different optical [18,19] or voltammetric [20] sensors for RDX were also reported. These included the fluorescence detection of RDX with an acridinium dye, [18] or the application of NADH-functionalized quantum dots.[21] Also, a competitive fluorescence immunoassay for the detection of RDX was reported.[22] The sensitivities accomplished by these methods are, however, unsatisfactory for analyzing trace amounts of the RDX explosive.Surface plasmon resonance (SPR) is a versatile method for probing changes in the refractive index occurring on thin metal films as a result of recognition events or chemical reactions. [23,24] Numerous SPR sensors and biosensors were developed, [25][26][27] and metal NPs were implemented to enhance the SPR response and to amplify SPR-based sensors. [28,29] The electronic coupling between the localized plasmon of the metallic NPs (e.g., Au NPs) and the surface plasmon wave enhances the SPR response and, thus, the labeling of recognition complexes with metallic NPs amplifies the sensing events. Different biosensing processes, such as DNA hybridization, [30] formation of immunocomplexes, [31] and the probing of biocatalytic transformations, [32] used Au NPs as labels for amplified SPR analyses. Recently, composites of bisaniline-crosslinked Au NPs were electropolymerized on Au electrodes, and the resulting matrices were used for the ultrasensitive SPR detection of TNT.[33] The formation of p-donor-acceptor complexes ...

Electroanalytical Applications of Metallic Nanoparticles and Supramolecular Nanostructures

“…Similar specific sensing of 1,3,5-trinitrotriazine, (29), RDX, was demonstrated with the Kemps acid, (30), -imprinted Au NPs composite [43]. Figure 6A shows the sensogram corresponding to the reflectance change of the imprinted Au NPs composite upon interaction with different concentrations of RDX.…”

“…Similarly, the imprint of molecular recognition sites for the 1,3,5-trinitrotriazine, RDX, (29), explosive has involved the use of Kemps acid (30) as an imprinting analog molecule [43]. RDX, (29), exists in a "chair-like" configuration, where the three nitro groups exist in quasiaxial positions.…”

“…Indeed, different biosensing platforms for analyzing antigen-antibody complexes [39], DNA hybridization [40], formation of aptamer-substrate complexes [22], and to follow biocatalytic processes [41], were developed. Figure 5A depicts the principles to electrosynthesize the imprinted Au NPs composites on Au electrodes and to use the resulting matrices for the SPR analysis of explosives [42,43]. Au NPs capped with electropolymeriza- (23) by the opening of the thiolated nucleic acid hairpin (22), associated with the electrode, and the formation of an aptamer-AMP complex, and the regeneration of the sensing electrode.…”

A novel double-layer molecularly imprinted polymer film based surface plasmon resonance for determination of testosterone in aqueous media

“…SPR was introduced in the early 1990s as the underlying technology in affinity biosensors for biomolecular interaction analysis [5]. Now it has become a widely used analytical technique to monitor not only for DNA [6], protein binding and environmental contaminants [7,8], but also for small molecule micro-arrays [9].…”

Transcription-Type Protein Imprinted Polymers for SPR Sensing Prepared Using Target-immobilized Stamps based on Submicrometer-Sized Particles via Biotin-Avidin Linkage

“…To address this issues, surface imprinting techniques have been developed, where the imprinted cavities can be constructed only on the surface of MIPs, resulting in more effective removal of template molecules and improvement of accessibility of the imprinted cavities [33][34][35][36][37][38][39]. Although surface imprinting by surface-initiated polymerization has been reported [29,30] where the polymer thickness is significantly important and should be optimized, transcription-type molecular imprinting seems to be a cogent technique for the surface imprinting; the technique involves radical polymerization of pre-polymerization mixtures in between a target proteins-immobilized stamp and a substrate on which MIPs are to be prepared.…”