High sensitive optical-chemical sensors based on optical fibers in a reflection scheme combined with C-shaped waveguides of MIP-microbeads.

In order to monitor analytes in liquid matrices, optical fiber probes in reflection mode can be exploited in several application fields. This work presents a novel sensing approach based on C-shaped waveguides obtained by filling PVC C-shaped channels with microbeads of molecularly imprinted polymers (MIP-microbeads). Specifically, for the first time, MIP microbeads are used as a sensitive core of optical waveguides with several advantages.

Photonics for Bioapplications: Sensors and Technology.

Over the past decade, interest in advancing photonic systems for bioapplications has been steadily growing, and various key factors have driven this trend [...

Low-cost optical fiber sensors for the portable detection of cortisol and .

Detection of biomarkers, as well as bacterial infection levels, plays an important role in clinical analysis. Development in research for fast, high-sensitivity, and selective sensors has a key role in decision-making during a health issue. Aligning to these features, low-cost biomarkers and bacteria population detection methods should be developed in order to make clinical trials more accessible to the whole of society.

Plasmonic optical fiber biosensors for ultra-low detection of respiratory syncytial virus via point-of-care tests.

Respiratory syncytial virus (RSV) is a major cause of bronchiolitis and pneumonia, particularly in children, the elderly, and immunocompromised individuals. Despite significant health impacts, annual RSV-related hospitalizations may be underreported due to undertesting and limited diagnostic sensitivity. Point-of-care tests (POCTs) could enhance the rapid and accurate detection of RSV, enabling timely treatment and reducing hospitalizations.

Plasmonic Optical Fibre-Based Point-of-Care Test for Periodontal MIP-1α Detection: A Validation Study of a Multiplexed Biosensor Prototype.

Introduction: The aim of this study was to assess the analytical performance of a multiplexed plasmonic optical fibre-based point-of-care test (POCT) in detecting and quantifying salivary macrophage inflammatory protein-1 alpha (MIP-1α) by comparing it with a standard enzyme-linked immunosorbent assay (ELISA).

Methods: Three plastic optical fibres (POFs) were modified to host a self-assembled monolayer (SAM) of anti-MIP-1α antibodies. Each of them was interposed between a light source and a spectrometer to detect the variations in the refractive index at the POF-SAM interface caused by surface plasmon resonance (SPR) when the antibody-analyte binding occurred.

An Extrinsic Optical Fiber Sensor Probe with Micrometer Size via a C-Shaped Waveguide with a Core of MIP.

Optical-chemical sensors based on optical fibers can be made in reflection or transmission schemes. In the reflection scheme, the sensing area is typically present at the end of the fiber, and the light source and the detector are placed on the same side of the fiber. This approach can be exploited to achieve chemical probes useful in several application fields where remote sensing is required.

Detecting Attomolar Concentrations of Interleukin IL-17A via Pollen-Based Nanoplasmonic Biochips.

Interleukins are involved in several diseases and cancers, and their detection and monitoring are of great interest. Their low abundance and short half-lives suggest the need to develop rapid, specific, and highly sensitive detection platforms, easily integrable in point-of-care (POC) systems. Among the other interleukins, interleukin IL-17A is associated with inflammations, neurodegenerative diseases, and cancers, and no biosensors have been previously reported for its detection.

An Attomolar-Level Optical Device for Monitoring Receptor-Analyte Interactions Without Functionalization Steps: A Case Study of Cytokine Detection.

A plastic optical fiber (POF)-based device for biosensing strategies has been developed to monitor several protein-protein interactions at ultra-low concentrations without functionalization processes, exploiting plasmonic phenomena. In this work, novel tests were applied to different kinds of analyte-receptor interactions, such as interleukins, where the bioreceptor's (protein antibody) molecular weight is roughly ten times that of the analyte (protein interleukin), while intracellular bioreceptors and small molecules at low molecular weight interactions have already been demonstrated via the same point-of-care test (POCT). The POCT was implemented by a white light source and a spectrometer connected via two POF-based chips connected in series: an innovative microcuvette chip and a D-shaped POF surface plasmon resonance (SPR) probe.

An MIP-Based PFAS Sensor Exploiting Nanolayers on Plastic Optical Fibers for Ultra-Wide and Ultra-Low Detection Ranges-A Case Study of PFAS Detection in River Water.

In this work, a novel optical-chemical sensor for the detection of per- and polyfluorinated substances (PFASs) in a real scenario is presented. The proposed sensing approach exploits the multimode characteristics of plastic optical fibers (POFs) to achieve unconventional sensors via surface plasmon resonance (SPR) phenomena. The sensor is realized by the coupling of an SPR-POF platform with a novel chemical chip based on different polymeric nanolayers over the core of a D-shaped POF, one made up of an optical adhesive and one of a molecularly imprinted polymer (MIP) for PFAS.

An Optical Device Based on a Chemical Chip and Surface Plasmon Platform for 2-Furaldehyde Detection in Insulating Oil.

2-Furaldehyde (2-FAL) is one of the main by-products of the degradation of hemicellulose, which is the solid material of the oil-paper insulating system of oil-filled transformers. For this reason, it has been suggested as a marker of the degradation of the insulating system; sensing devices for 2-FAL analysis in a wide concentration range are of high interest in these systems. An optical sensor system is proposed; this consists of a chemical chip, able to capture 2-FAL from the insulating oil, coupled with a surface plasmon resonance (SPR) probe, both realized on multimode plastic optical fibers (POFs).

An Efficient Bio-Receptor Layer Combined with a Plasmonic Plastic Optical Fiber Probe for Cortisol Detection in Saliva.

Cortisol is a clinically validated stress biomarker that takes part in many physiological and psychological functions related to the body's response to stress factors. In particular, it has emerged as a pivotal tool for understanding stress levels and overall well-being. Usually, in clinics, cortisol levels are monitored in blood or urine, but significant changes are also registered in sweat and saliva.

Splitter-Based Sensors Realized via POFs Coupled by a Micro-Trench Filled with a Molecularly Imprinted Polymer.

An optical-chemical sensor based on two modified plastic optical fibers (POFs) and a molecularly imprinted polymer (MIP) is realized and tested for the detection of 2-furaldehyde (2-FAL). The 2-FAL measurement is a scientific topic of great interest in different application fields, such as human health and life status monitoring in power transformers. The proposed sensor is realized by using two POFs as segmented waveguides (SW) coupled through a micro-trench milled between the fibers and then filled with a specific MIP for the 2-FAL detection.

POF-based biosensors for cortisol detection in seawater as a tool for aquaculture systems.

A surface plasmon resonance (SPR) phenomenon implemented via D-shaped polymer optical fiber (POF) is exploited to realize cortisol biosensors. In this work, two immonosensors are designed and developed for the qualitative as well as quantitative measurement of cortisol in artificial and real samples. The performances of the POF-based biosensors in cortisol recognition are achieved using different functionalization protocols to make the same antibody receptor layer over the SPR surface via cysteamine and lipoic acid, achieving a limit of detection (LOD) of 0.

Toward Nano- and Microplastic Sensors: Identification of Nano- and Microplastic Particles via Artificial Intelligence Combined with a Plasmonic Probe Functionalized with an Estrogen Receptor.

Nano- and microplastic particles are a global and emerging environmental issue that might pose potential threats to human health. The present work exploits artificial intelligence (AI) to identify nano- and microplastics in water by monitoring the interaction of the sample with a sensitive surface. An estrogen receptor (ER) grafted onto a gold surface, realized on a nonexpensive and easy-to-produce plastic optical fiber (POF) platform in order to excite a surface plasmon resonance (SPR) phenomenon, has been developed in order to carry out a "smart" sensitive interface (ER-SPR-POF interface).

3D-printed biosensors in biomedical applications exploiting plasmonic phenomena and antibody self-assembled monolayers.

In this work, a 3D-printed plasmonic chip based on a silver-gold bilayer was developed in order to enhance the optical response of the surface plasmon resonance (SPR) probe. More specifically, numerical and experimental results were obtained on the 3D-printed SPR platform based on a silver-gold bilayer. Then, the optimized probe's gold plasmonic interface was functionalized with a specific antibody directed against the p27 protein (p27), an important cell cycle regulator.

Plasmon resonance biosensor for interleukin-1β point-of-care determination: A tool for early periodontitis diagnosis.

Among pro-inflammatory cytokines, Interleukin-1β is crucially involved in several inflammatory-based diseases and even cancer. Increased Interleukin-1β levels in oral fluids have been proposed as an early marker of periodontitis, a broadly diffused chronic inflammatory condition of periodontal-supporting tissues, leading eventually to tooth loss. We describe the development of a portable surface-plasmon-resonance-based optical fiber probe suitably coated with an anti-Interleukin-1β antibody monolayer.

Plasmonic immunosensors based on spoon-shaped waveguides for fast and on-site ultra-low detection of ochratoxin A in coffee samples.

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.

Immuno-SPR biosensor for the detection of Brucella abortus.

A proof of principle biosensor for the Brucella abortus recognition onsite is presented. The system is based on a plasmonic optical fiber probe functionalized with an oriented antibody layer immobilized on a short polyethyleneglycol (PEG) interface through carbodiimide chemistry and protein G as an intermediate layer. The biosensor is inserted in a holder built in 3D printing technology, obtaining a custom holder useful for housing the sample to be measured and the equipment.

A novel plasmonic optical-fiber-based point-of-care test for periodontal MIP-1α detection.

The analysis of salivary biomarkers as expression of periodontal health conditions has been proposed as a useful aid to conventional diagnostic approaches. In this study, we present a point-of-care test (POCT) exploiting a surface plasmon resonance (SPR)-based optical biosensor to detect salivary macrophage inflammatory protein (MIP)-1α, a promising marker of periodontitis. A plastic optical fiber (POF) was suitably modified and functionalized by an antibody self-assembled monolayer against MIP-1α for plasmonic detection.

Optimization of the immunorecognition layer towards Brucella sp. on gold surface for SPR platform.

A successful immunosensor is characterized by a proper antibody immobilization and orientation in order to enhance the antigen recognition. In this work, a thorough characterization of the antibody functionalized gold surface is performed to set up the best conditions to implement in an optical platform for the detection of Brucella sp. Two different strategies are evaluated, based on a random immobilization and on an oriented one: a direct antibody immobilization on carboxylic mixed polyethylene (PEG) self-assembled monolayer (SAM) or only carboxylic PEG SAM interface is compared to an oriented immobilization on a layer of protein G on the same PEG SAM interfaces.

A plasmonic gold nano-surface functionalized with the estrogen receptor for fast and highly sensitive detection of nanoplastics.

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.

Sensing Approaches Exploiting Molecularly Imprinted Nanoparticles and Lossy Mode Resonance in Polymer Optical Fibers.

In this work, two different lossy mode resonance (LMR) platforms based on plastic optical fibers (POFs) are developed and tested in a biochemical sensing scenario. The LMR platforms are based on the combination of two metal oxides (MOs), i.e.

Analysis of Plasmonic Sensors Performance Realized by Exploiting Different UV-Cured Optical Adhesives Combined with Plastic Optical Fibers.

Polymer-based surface plasmon resonance (SPR) sensors can be used to realize simple, small-size, disposable, and low-cost biosensors for application in several fields, e.g., healthcare.

Soft molecularly imprinted nanoparticles with simultaneous lossy mode and surface plasmon multi-resonances for femtomolar sensing of serum transferrin protein.

The simultaneous interrogation of both lossy mode (LMR) and surface plasmon (SPR) resonances was herein exploited for the first time to devise a sensor in combination with soft molecularly imprinting of nanoparticles (nanoMIPs), specifically entailed of the selectivity towards the protein biomarker human serum transferrin (HTR). Two distinct metal-oxide bilayers, i.e.

A Novel Approach to Realize Plasmonic Sensors via Multimode Optical Waveguides: A Review.

In recent decades, the Surface Plasmon Resonance (SPR) phenomenon has been utilized as an underlying technique in a broad range of application fields. Herein, a new measuring strategy which harnesses the SPR technique in a way that is different from the classical methodology was explored by taking advantage of the characteristics of multimode waveguides, such as plastic optical fibers (POFs) or hetero-core fibers. The sensor systems based on this innovative sensing approach were designed, fabricated, and investigated to assess their ability to measure various physical features, such as magnetic field, temperature, force, and volume, and to realize chemical sensors.