A Nanoplasmonic-Based Biosensing Approach for Wide-Range and Highly Sensitive Detection of Chemicals

Abstract

In a specific biosensing application, a nanoplasmonic sensor chip has been tested by an experimental setup based on an aluminum holder and two plastic optical fibers used to illuminate and collect the transmitted light. The studied plasmonic probe is based on gold nanograting, realized on the top of a Poly(methyl methacrylate) (PMMA) chip. The PMMA substrate could be considered as a transparent substrate and, in such a way, it has been already used in previous work. Alternatively, here it is regarded as a slab waveguide. In particular, we have deposited upon the slab surface, covered with a nanograting, a synthetic receptor specific for bovine serum albumin (BSA), to test the proposed biosensing approach. Exploiting this different experimental configuration, we have determined how the orientation of the nanostripes forming the grating pattern, with respect to the direction of the input light (longitudinal or orthogonal), influences the biosensing performances. For example, the best limit of detection (LOD) in the BSA detection that has been obtained is equal to 23 pM. Specifically, the longitudinal configuration is characterized by two observable plasmonic phenomena, each sensitive to a different BSA concentration range, ranging from pM to µM. This aspect plays a key role in several biochemical sensing applications, where a wide working range is required.

Bovine Serum Albumin Protein Detection by a Removable SPR Chip Combined with a Specific MIP Receptor

“…Therefore, in this work, we did not report these aspects. 3, the proposed SPR sensor based on a PMMA slab waveguide has shown a minor LOD value compared to SPR D-shaped POFs probes [28] and a major LOD value if compared to plasmonic nanograting-based POF sensor configurations [33,34], combined with the same MIP receptor. A comparative analysis for BSA sensors regarding the LOD and the detection range which was obtained by exploiting different sensing approaches, has been summarized in Table 3.…”

“…By considering the linear behavior at low BSA concentrations, the latter is used to calculate the limit of detection (LOD), defined as the ratio between two times the standard deviation of the blank (standard error of λ 0 reported in Table 1) and the sensitivity at low concentrations. We used the same LOD definition adopted in [28,33,34] to compare the obtained performances with those of SPR D-shaped POF sensors and those of plasmonic nanograting-based POF sensors, both functionalized with the same MIP receptor for BSA. We have also presented a characterization of the used MIP (in terms of selectivity, stability, etc.)…”

Cost-Effective Fiber Optic Solutions for Biosensing

“…Alternatively, the PMMA substrate can be regarded as a multimode slab waveguide, as shown in Figure 8 b, similar to other plasmonic sensor chips [ 65 , 66 ]. In particular, a gold nano-film can be deposited on the PMMA chip, obtaining an SPR sensor chip [ 67 , 68 ] or producing a gold nanograting on the PMMA chip surface via EBL, generating a nano-plasmonic sensor chip [ 69 ]. By using the sensor setup illustrated in Figure 8 b, when a gold nano-film is present, the sensor’s performance is similar to that obtained by an SPR D-shaped POF sensor [ 64 ], whereas, when a nano-plasmonic chip is used, the orientation of the nanostripes forming the grating pattern, with respect to the direction of the input light (longitudinal or orthogonal), influences the biosensing performances [ 69 ].…”

Optical properties and complex refractive index of Co doped ZnO waveguide thin films elaborated by spray pyrolysis

“…Optical fibers are relatively flexible and immune to electromagnetic interference so they found use in communications. Transparent thin films waveguides are of high quality, controllable and efficient and by that, they had been employed as bio and chemical sensors [1][2][3], integrated optical amplifier [4] and a guided layer in total internal reflection fluorescence microscope [5] to name a few. A dielectric waveguide can be defined as any structure used to control the flow of electromagnetic waves in a certain direction.…”