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The high toxicity and occurrence of ochratoxin A (OTA) in grains and foods has been a growing concern due to the impacts on health and the economy in many countries. In this sense, simplified devices with high sensitivity and specificity for local monitoring are enthusiastically pursued. In this work, we report for the first time the detection of ochratoxin A in coffee samples using a spoon-shaped waveguide immunosensor. The biosensor was built with the surface of the spoon-shaped waveguide covered by a 60 nm layer of gold to enable the SPR phenomenon. The measurements indicated a linear relationship between the change in the SPR phenomenon values and the OTA concentration in the range from 0.2 ppt to 5 ppt. When analyzed in coffee samples, the biosensor was highly selective and did not suffer matrix interference. The developed biosensor represents a promising analytical device for coffee quality analyses, as it is portable, simple, and suitable for onsite detection of target analytes., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Nanoplastics are a global emerging environmental problem whose effects might pose potential threats to the human's health. Despite the relevance of the issue, fast, reliable and quantitative in situ analytical approaches to determine nanoplastics are not yet available. The aim of this work was to devise an optical sensor with the goal of direct detecting and quantifying nanoplastics in seawater without sample pre-treatments. To this purpose, a nano-plasmonic biosensor was developed by exploiting an Estrogen Receptor (ER) recognition element grafted onto a polymer-based gold nanograting (GNG) plasmonic platform. The ER-GNG biosensor required just minute sample volumes (2 μL), allowed rapid detection (3 min) and enabled to determine nanoplastics in simulated seawater with a linear dynamic concentrations range of 1-100 ng/mL, thus encompassing the expected environmental loads. The nanostructured grating (GNG) provided remarkable performance enhancements, extending the measurement range across five orders of magnitude, thanks to the both the SPR and the localized SPR phenomena occurring at the GNG chip. At last, the ER-GNG biosensor was tested on real seawater samples collected in the Naples area and the results (∼30 ng/mL) were verified by a conventional approach (filtration and evaporation), confirming the ER-GNG sensor offers a straightforward and highly sensitive method for the direct in-field nanoplastics monitoring., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.)

Point-of-Care tests based on biomarkers, useful to monitor acute and chronic inflammations, are required for advances in medicine. In this scope, a key role is played by pro-inflammatory cytokines, of which interleukin 6 (IL-6) is generally thought as one of the most relevant. To use IL-6 in real scenarios, detection in ultra-low concentration ranges is required. In this work, two IL-6 biosensors are obtained by exploiting the combination of the same antibody self-assembled monolayer with two different plasmonic probes. This approach has demonstrated, via experimental results, that two different IL-6 concentration ranges can be explored. More specifically, IL-6 in an atto-femto molar range can be detected via polymer-based nanoplasmonic chips. On the other hand, a pico-nano molar range is obtained by a surface plasmon resonance platform in plastic optical fibers. As a proof of concept, the detection of IL-6 at the femto molar range has been obtained in Saliva and Serum. The results show that the proposed sensing approach could be useful in developing Point-of-Care devices based on a general setup with the capability to exploit both the plasmonic biosensor chips to monitor the IL-6 in the concentration range of interest, to provide an important support for the diagnosis and monitoring of oral and systemic diseases., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

A specific aptameric sequence has been immobilized on short polyethyleneglycol (PEG) interface on gold nano-film deposited on a D-shaped plastic optical fiber (POFs) probe, and the protein binding has been monitored exploiting the very sensitive surface plasmon resonance (SPR) phenomenon. The receptor-binding domain (RBD) of the SARS-CoV-2 spike glycoprotein has been specifically used to develop an aptasensor. Surface analysis techniques coupled to fluorescence microscopy and plasmonic analysis have been utilized to characterize the biointerface. Spanning a wide protein range (25 ÷ 1000 nM), the SARS-Cov-2 spike protein was detected with a Limit of Detection (LoD) of about 37 nM. Different interferents (BSA, AH1N1 hemagglutinin protein and MERS spike protein) have been tested confirming the specificity of our aptasensor. Finally, a preliminary test in diluted human serum encouraged its application in a point-of-care device, since POF-based aptasensor represent a potentially low-cost compact biosensor, characterized by a rapid response, a small size and could be an ideal laboratory portable diagnostic tool., (Copyright © 2021 Elsevier B.V. All rights reserved.)

In this study we developed an optical fiber biosensor able to detect the presence of naphthalene in sea-water. With this aim, we designed and produced an antibody specific for the naphthalene molecule. The capability of the antibody to bind to naphthalene was characterized by ELISA tests. A surface plasmon resonance (SPR) sensor platform was realized by sputtering a gold layer on a modified plastic optical fiber (POF). The gold surface was derivatizated and functionalized with the produced antibody by using the EDC/NHS amino-coupling immobilization protocol. The obtained results indicated that the POF-biosensor is able to sense the presence of naphthalene in a sea-water solution. The limit of detection (LOD) value was calculated to be 0.76 ng/mL, a value lower than the maximum residue limit value of naphthalene (0.13 µg/mL) referred as the water environmental quality standards (EQS). In addition, to the high sensitivity of the assay, it is remarkable to point out the possibility to monitor the presence of naphthalene in a real sea water solution by exploiting a simple experimental setup with a remote sensing capability offered by the POF-biosensor., (Copyright © 2018 Elsevier B.V. All rights reserved.)

A novel surface plasmon resonance (SPR) optical fiber biosensor, able to bind perfluorooctanoate and perfluorooctanesulfonate compounds, is presented. In the first step, an ad hoc antibody compound has been designed, produced and tested by ELISA, then, in the second step, the gold surface of a plastic optical fiber sensor has been derivatizated and functionalized with this new bio-receptor, able to bind target analytes with high affinity and selectivity. The experimental data have shown that the developed SPR optical fiber biosensor makes it possible to detect these compounds. One advantage of this approach stems from the possibility to monitor the perfluorinated compounds in the environment exploiting the remote sensing capability offered by the optical fibers. The measurements were performed in laboratory, also exploiting matrices mimicking the real environment. The limit of detection of the assay was 0.21ppb, a value that is lower than the maximum residue limit fixed by the European Union regulations., (Copyright © 2017 Elsevier B.V. All rights reserved.)

The introduction of new compact systems for sensitive, fast and simplified analysis is currently playing a substantial role in the development of point-of-care solutions aimed to assist both prognosis and diagnosis. Here we report a simple and low cost biosensor based on Surface Plasmon Resonance (SPR) taking advantage of a plastic optical fiber (POF) for the detection of Vascular endothelial growth factor (VEGF), selected as a circulating protein potentially associated with cancer. Our system is based onto two crucial aspects. By one hand, the functional layer which allows the transduction signal is based on DNA aptamers, short oligonucleotide sequences that bind to non-nucleic acid targets with high affinity and specificity. By the other hand, the light guiding structure is based on a POF with a planar gold layer as the sensing region, which is particularly suitable for bioreceptors implementation. The sensor revealed to be really useful in the interface characterization. The developed system is relatively easy to realize and could well address the development of a rapid, portable and low cost diagnostic platform, with a sensitivity in the nanomolar range., (Copyright © 2015 Elsevier B.V. All rights reserved.)