Lab on Fiber Optrodes: Towards Point of Care Applications

A special issue of Biosensors (ISSN 2079-6374). This special issue belongs to the section "Optical and Photonic Biosensors".

Deadline for manuscript submissions: closed (20 November 2022) | Viewed by 16834

Special Issue Editors


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Guest Editor
Optoelectronic Group, Department of Engineering, University of Sannio, Corso Garibaldi 107, Benevento, Italy
Interests: nanobiophotonics; fiber optic nanoprobes; optical biosensors; plasmonics; lab-on-fiber, lab-in-a-needle
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Department of Engineering, University of Campania Luigi Vanvitelli, Via Roma 29, 81031 Aversa, Italy
Interests: optical sensors; biosensors and chemical sensors; optical fiber sensors and optoelectronic devices
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Guest Editor
Optoelectronics Group, Department of Engineering, University of Sannio, I-82100 Benevento, Italy
Interests: nanophotonics; fiber optic sensors; lab-on-fiber devices; chemical and biological sensing
Special Issues, Collections and Topics in MDPI journals

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Guest Editor
Institute of Applied Physics “Nello Carrara”, CNR-IFAC, Via Madonna del Piano 10, 50019 Sesto Fiorentino, Italy
Interests: bio-photonics and biomedical optics; fiber optics; plasmonics; optical devices; detectors; sensors and sensing
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The global COVID-19 pandemic of 2019–2020 made the world painfully aware of a testing availability that was far below the demand, leading to a considerable lag in the capacity to detect infections in a timely manner and a dramatic lack of diagnostic solutions able to face the rapid spread of the virus. In the current COVID scenario, the rampant nature of the epidemic infection has given rise to a great increase in demand for mass screening diagnosis and rapid monitoring modalities.

The same challenges are still open for cancer prevention and treatment, which remains the major burden of disease and the number one killer worldwide. Non-invasive cancer diagnosis (e.g., quantification of circulating tumor cells or extra vesicles such as exosomes), monitoring and management implemented at an early-stage lead to remarkable healthcare cost savings and improved health outcomes. 

The panorama of urgent testing needs has driven the demand for portable detection systems enabling the sensitive detection of pathogens and biomarkers at extremely low concentrations and providing instant results under a cost-effective scheme. Although considerable advances have been achieved in the area of point-of-care (POC) devices, several relevant technical challenges must be still overcome to finally offer automated, robust, reliable and cost-effective POC devices in order to fully explore their potential. Issues such as miniaturization, multiplexing, full automatization with network connection, mass production, microfluidics integration, and sample collection still posed severe barriers in the pipeline of POC research and development.
Considering the technological maturity that has been achieved so far, at both fabrication and application levels, lab-on-fiber technology has the potential to significantly impact the technological roadmap towards advanced POC applications, though the development of the fundamental technological pillars at the basis of next-generation of POCs opens up unprecedented perspectives for such devices in the field of healthcare management. In this context, the aim of this Special Issue is to present the current evolution and perspectives of lab-on-fiber optrodes, with a special focus on innovative developments of transducer schemes, smart materials and receptors, nanostructures, and POC applications of optical fiber sensor systems. Particular emphasis will be given to the sensitive and specific detection of disease-related biomarkers, responding to urgent and open clinical needs. 
We invite authors to submit examples of advanced lab-on-fiber optrodes—both label-free and label-based—for life science applications that can be translated to clinical practice in the future. 

Prof. Dr. Andrea Cusano
Prof. Dr. Nunzio Cennamo
Prof. Dr. Marco Consales
Dr. Francesco Chiavaioli
Guest Editors

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Keywords

  • Point-of-Care (POC)
  • Optical fiber biosensors
  • Optical fiber sensor systems
  • Lab-on-Fiber Technology
  • Optical fiber nano-sensors
  • Nanomaterials for in-fiber biosensing
  • Molecular Diagnostics
  • Liquid Biopsy
  • Tissue biopsy
  • Nanotechnology
  • Nanophotonics
  • Biophotonics

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Published Papers (5 papers)

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Research

14 pages, 5049 KiB  
Article
Long Period Grating Mach–Zehnder Interferometer Based Immunosensor with Temperature and Bulk Refractive Index Compensation
by Peizhou Wu, Liangliang Liu, Stephen P. Morgan, Ricardo Correia and Serhiy Korposh
Biosensors 2022, 12(12), 1099; https://doi.org/10.3390/bios12121099 - 30 Nov 2022
Cited by 2 | Viewed by 1613
Abstract
A long period grating Mach–Zehnder interferometer (LPGMZI) that consists of two identical long period gratings (LPGs) in a single fibre was developed to measure immunoglobulin M (IgM). The measured spectrum has fringes due to the interference between the core mode and cladding mode. [...] Read more.
A long period grating Mach–Zehnder interferometer (LPGMZI) that consists of two identical long period gratings (LPGs) in a single fibre was developed to measure immunoglobulin M (IgM). The measured spectrum has fringes due to the interference between the core mode and cladding mode. This immunosensor inherits the advantages of an LPG and has the potential to compensate for unwanted signal changes due to bulk refractive index (RI) and temperature fluctuations by analysing interference fringes and their envelope. The external RI was measured from 1.3384 to 1.3670 in two different cases: (i) only the connecting section between the two LPGs is immersed or (ii) the whole LPGMZI is immersed. The fringes shift with an external RI in both scenarios, whereas the envelope stays still in case (i) or shifts at the same rate as the fringes in case (ii). The LPGMZI was also characterised at different temperatures between 25 °C and 30 °C by placing the whole LPGMZI in a water bath. The fringes and envelope shift at the same rate with temperature. The LPGMZI platform was then used to create an IgM immunosensor. The connecting section between the two LPGs was functionalised with anti-IgM and immersed into solutions with IgM concentrations from 20 μg/mL to 320 μg/mL. The fringes shift with IgM concentration and the envelope remains static. The results from this work show that LPGMZI has the potential to compensate for the temperature and bulk RI fluctuations and perform as a portable biosensor platform. Full article
(This article belongs to the Special Issue Lab on Fiber Optrodes: Towards Point of Care Applications)
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18 pages, 3547 KiB  
Article
Differential Refractometric Biosensor for Reliable Human IgG Detection: Proof of Concept
by João P. Mendes, Luís C. C. Coelho, Pedro A. S. Jorge and Carlos M. Pereira
Biosensors 2022, 12(7), 515; https://doi.org/10.3390/bios12070515 - 12 Jul 2022
Cited by 9 | Viewed by 2404
Abstract
A new sensing platform based on long-period fiber gratings (LPFGs) for direct, fast, and selective detection of human immunoglobulin G (IgG; Mw = 150 KDa) was developed and characterized. The transducer’s high selectivity is based on the specific interaction of a molecularly imprinted [...] Read more.
A new sensing platform based on long-period fiber gratings (LPFGs) for direct, fast, and selective detection of human immunoglobulin G (IgG; Mw = 150 KDa) was developed and characterized. The transducer’s high selectivity is based on the specific interaction of a molecularly imprinted polymer (MIPs) design for IgG detection. The sensing scheme is based on differential refractometric measurements, including a correction system based on a non-imprinted polymer (NIP)-coated LPFG, allowing reliable and more sensitive measurements, improving the rejection of false positives in around 30%. The molecular imprinted binding sites were performed on the surface of a LPFG with a sensitivity of about 130 nm/RIU and a FOM of 16 RIU−1. The low-cost and easy to build device was tested in a working range from 1 to 100 nmol/L, revealing a limit of detection (LOD) and a sensitivity of 0.25 nmol/L (0.037 µg/mL) and 0.057 nm.L/nmol, respectively. The sensor also successfully differentiates the target analyte from the other abundant elements that are present in the human blood plasma. Full article
(This article belongs to the Special Issue Lab on Fiber Optrodes: Towards Point of Care Applications)
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15 pages, 6832 KiB  
Article
Biofilm Detection by a Fiber-Tip Ball Resonator Optical Fiber Sensor
by Aida Rakhimbekova, Baizak Kudaibergenov, Damir Moldabay, Albina Zharylgap, Obinna M. Ajunwa, Enrico Marsili and Daniele Tosi
Biosensors 2022, 12(7), 481; https://doi.org/10.3390/bios12070481 - 30 Jun 2022
Cited by 6 | Viewed by 3481
Abstract
Bacterial biofilms are one of the most important challenges that modern medicine faces due to the difficulties of diagnosis, antibiotic resistance, and protective mechanisms against aggressive environments. For these reasons, methods that ensure the inexpensive and rapid or real-time detection of biofilm formation [...] Read more.
Bacterial biofilms are one of the most important challenges that modern medicine faces due to the difficulties of diagnosis, antibiotic resistance, and protective mechanisms against aggressive environments. For these reasons, methods that ensure the inexpensive and rapid or real-time detection of biofilm formation on medical devices are needed. This study examines the possibilities of using optical- and fiber-based biosensors to detect and analyze early bacterial biofilms. In this study, the biofilm-forming model organism Pseudomonas aeruginosa was inoculated on the surface of the optical sensor and allowed to attach for 2 h. The biosensors were made by a fiber-tip ball resonator, fabricated through a CO2 laser splicer on a single-mode fiber, forming a weak reflective spectrum. An optical backscatter reflectometer was used to measure the refractive index detected by the sensors during different growth periods. The early biofilm concentration was determined by crystal violet (CV) binding assay; however, such a concentration was lower than the detection limit of this assay. This work presents a new approach of biofilm sensing in the early attachment stage with a low limit of detection up to 10−4 RIU (refractive index units) or 35 ± 20 × 103 CFU/mL (colony formed units). Full article
(This article belongs to the Special Issue Lab on Fiber Optrodes: Towards Point of Care Applications)
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12 pages, 3569 KiB  
Article
Lossy Mode Resonance Based Microfluidic Platform Developed on Planar Waveguide for Biosensing Applications
by Melanys Benítez, Pablo Zubiate, Ignacio Del Villar, Abián B. Socorro-Leránoz and Ignacio R. Matías
Biosensors 2022, 12(6), 403; https://doi.org/10.3390/bios12060403 - 10 Jun 2022
Cited by 13 | Viewed by 2635
Abstract
The development of resonance phenomena-based optical biosensors has gained relevance in recent years due to the excellent optical fiber properties and progress in the research on materials and techniques that allow resonance generation. However, for lossy mode resonance (LMR)-based sensors, the optical fiber [...] Read more.
The development of resonance phenomena-based optical biosensors has gained relevance in recent years due to the excellent optical fiber properties and progress in the research on materials and techniques that allow resonance generation. However, for lossy mode resonance (LMR)-based sensors, the optical fiber presents disadvantages, such as the need for splicing the sensor head and the complex polarization control. To avoid these issues, planar waveguides such as coverslips are easier to handle, cost-effective, and more robust structures. In this work, a microfluidic LMR-based planar waveguide platform was proposed, and its use for biosensing applications was evaluated by detecting anti-immunoglobulin G (anti-IgG). In order to generate the wavelength resonance, the sensor surface was coated with a titanium dioxide (TiO2) thin-film. IgG antibodies were immobilized by covalent binding, and the detection assay was carried out by injecting anti-IgG in PBS buffer solutions from 5 to 20 μg/mL. The LMR wavelength shifted to higher values when increasing the analyte concentration, which means that the proposed system was able to detect the IgG/anti-IgG binding. The calibration curve was built from the experimental data obtained in three repetitions of the assay. In this way, a prototype of an LMR-based biosensing microfluidic platform developed on planar substrates was obtained for the first time. Full article
(This article belongs to the Special Issue Lab on Fiber Optrodes: Towards Point of Care Applications)
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18 pages, 3920 KiB  
Article
Design and Optimization of All-Dielectric Fluorescence Enhancing Metasurfaces: Towards Advanced Metasurface-Assisted Optrodes
by Hiba Alhalaby, Maria Principe, Haitham Zaraket, Patrizio Vaiano, Anna Aliberti, Giuseppe Quero, Alessio Crescitelli, Valentina Di Meo, Emanuela Esposito, Marco Consales and Andrea Cusano
Biosensors 2022, 12(5), 264; https://doi.org/10.3390/bios12050264 - 21 Apr 2022
Cited by 10 | Viewed by 3416
Abstract
The need for miniaturized biological sensors which can be easily integrated into medical needles and catheters for in vivo liquid biopsies with ever-increasing performances has stimulated the interest of researchers in lab-on-fiber (LOF) technology. LOF devices arise from the integration of functional materials [...] Read more.
The need for miniaturized biological sensors which can be easily integrated into medical needles and catheters for in vivo liquid biopsies with ever-increasing performances has stimulated the interest of researchers in lab-on-fiber (LOF) technology. LOF devices arise from the integration of functional materials at the nanoscale on the tip of optical fibers, thus endowing a simple optical fiber with advanced functionalities and enabling the realization of high-performance LOF biological sensors. Consequently, in 2017, we demonstrated the first optical fiber meta-tip (OFMT), consisting of the integration of plasmonic metasurfaces (MSs) on the optical fiber end-face which represented a major breakthrough along the LOF technology roadmap. Successively, we demonstrated that label-free biological sensors based on the plasmonic OFMT are able to largely overwhelm the performance of a standard plasmonic LOF sensor, in view of the extraordinary light manipulation capabilities of plasmonic array exploiting phase gradients. To further improve the overall sensitivity, a labelled sensing strategy is here suggested. To this end, we envision the possibility to realize a novel class of labelled LOF optrodes based on OFMT, where an all-dielectric MS, designed to enhance the fluorescence emission by a labelled target molecule, is integrated on the end-face of a multimode fiber (MMF). We present a numerical environment to compute the fluorescence enhancement factor collected by the MMF, when on its tip a Silicon MS is laid, consisting of an array of cylindrical nanoantennas, or of dimers or trimers of cylindrical nanoantennas. According to the numerical results, a suitable design of the dielectric MS allows for a fluorescence enhancement up to three orders of magnitudes. Moreover, a feasibility study is carried out to verify the possibility to fabricate the designed MSs on the termination of multimode optical fibers using electron beam lithography followed by reactive ion etching. Finally, we analyze a real application scenario in the field of biosensing and evaluate the degradation in the fluorescence enhancement performances, taking into account the experimental conditions. The present work, thus, provides the main guidelines for the design and development of advanced LOF devices based on the fluorescence enhancement for labelled biosensing applications. Full article
(This article belongs to the Special Issue Lab on Fiber Optrodes: Towards Point of Care Applications)
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