Fiber Optic Biosensor Research Articles

Immunosensor Based on Long-Period Fiber Gratings for Detection of Viruses Causing Gastroenteritis

Since the norovirus is the main cause of acute gastroenteritis all over the world, its fast detection is crucial in medical diagnostics. In this work, a rapid, sensitive, and selective optical fiber biosensor for the detection of norovirus virus-like particles (VLPs) is reported. The sensor is based on highly sensitive long-period fiber gratings (LPFGs) coated with antibodies against the main coat protein of the norovirus. Several modification methods were verified to obtain reliable immobilization of protein receptors on the LPFG surface. We were able to detect 1 ng/mL norovirus VLPs in a 40-min assay in a label-free manner. Thanks to the application of an optical fiber as the sensor, there is a possibility to increase the user’s safety by separating the measurement point from the signal processing setup. Moreover, our sensor is small and light, and the proposed assay is straightforward. The designed LPFG-based biosensor could be applied in both fast norovirus detection and in vaccine testing.

New Optical Fiber Biosensor Method for Glucose in Serum

This paper presents the design and analysis of optical fiber biological sensor to measure and monitor the glucose ratio in blood samples. Simulations are carried out using Optisystem software to determine the optical power and mode for each sample. The sensing was accomplished by design Mach-Zehnder interferometer with using multimode fibers. The cladding of these fibers is stripped out of the fiber part. In addition, the wavelength of the light source has to be absorbable by the glucose in order to be detected. As a result, the refractive index (RI) of different serum glucose level has increased linearly by increasing the serum glucose level while the parameters of the RI step and the output power decreased linearly by increasing the RI of different serum glucose level. This result can be concluded as a new method for serum glucose level assessment.

Label-free detection of breast cancer biomarker using silica microfiber interferometry

Sensitive detection of HER2 biomarkers is critical for clinical diagnostics of breast cancer while such detection is quite challenging due to the rapid detection of low concentration of HER2 biomarkers in complex biological media. A compact and label-free optical fiber sensor based on silica microfiber interferometry for detecting HER2 in serum has been proposed and experimentally demonstrated. The antibodies immobilized on the microfiber surface play the roles of the specific immuno-tentacles on catching the HER2 targets. The change of the surface refractive index attributed to the immunoreactions could be captured by the optical fiber sensor and transduced into a significant wavelength shift in the interferometric fringe. The proposed fiber-optic biosensor shows an improved sensitivity of 0.1 nm/(ng/mL), even in a serum matrix. The advantages of simple detection scheme and ease of miniaturization might make the biosensor a promising platform for clinical cancer diagnosis and prognosis.

Multiplexed Remote SPR Detection of Biological Interactions through Optical Fiber Bundles.

The development of sensitive methods for in situ detection of biomarkers is a real challenge to bring medical diagnosis a step forward. The proof-of-concept of a remote multiplexed biomolecular interaction detection through a plasmonic optical fiber bundle is demonstrated here. The strategy relies on a fiber optic biosensor designed from a 300 µm diameter bundle composed of 6000 individual optical fibers. When appropriately etched and metallized, each optical fiber exhibits specific plasmonic properties. The surface plasmon resonance phenomenon occurring at the surface of each fiber enables to measure biomolecular interactions, through the changes of the retro-reflected light intensity due to light/plasmon coupling variations. The functionalization of the microstructured bundle by multiple protein probes was performed using new polymeric 3D-printed microcantilevers. Such soft cantilevers allow for immobilizing the probes in micro spots, without damaging the optical microstructures nor the gold layer. We show here the potential of this device to perform the multiplexed detection of two different antibodies with limits of detection down to a few tenths of nanomoles per liter. This tool, adapted for multiparametric, real-time, and label free monitoring is minimally invasive and could then provide a useful platform for in vivo targeted molecular analysis.

Refractive Index Sensors Based on Ti3C2Tx MXene Fibers

The sensitivity of fiber optic biosensors to detect trace biochemical molecules is highly challenging. Two-dimensional (2D) MXene is recently found to have strong sensitivity enhancement on biosens...

Anomalous Sensitivity Enhancement of D-Shaped Fiber-Based Sandwiched Structure Optofluidic Sensor

A novel mechanism of sensitivity enhancement of D-shaped fiber-based surface plasmon resonance (SPR) sensors for the optofluidic device has been proposed. The sandwiched structure optofluidic platform is developed with metal-coated D-shaped fiber as the sensing device, while another thin metal layer is situated under the inner wall of the substrate as a second metal layer to construct the sandwiched microchannel. It has been found that the sensitivity of the D-type fiber SPR sensor is enhanced significantly with the sandwiched metal-coated structure of microchannel. In the proposed structure, the measurand analyte is considered as a sandwich channel layer between two thin metal layers. The sensitivity of the proposed structure is dependent on the volume of the measurand and the thickness of the metal layers. The computed sensitivity with a double metal layer and sandwich measurand layer concept is 4085 nm/RIU in the region of 1.33 to 1.36. The sensitivity is enhanced by more than a factor of `2.3' in comparison with the sensitivity of the normal D-shape fiber SPR sensor. It can be enhanced further up to ~12,500 nm/RIU by the deposition of higher RI polymeric overlay just above the second metal layer. The computed resolution of the proposed sensor with standard interrogation technique is ~1 × 10 -7 which is quite competitive within the optical fiber sensor domain. A detailed numerical analysis has been accomplished. This structure will be useful in distinct chemical and biological sensing applications where the volume of an analyte is critical. This new concept of enhancement of sensitivity with limited measurand volume will open a new designing methodology for optical fiber biosensors.

A metal-organic zeolitic framework with immobilized urease for use in a tapered optical fiber urea biosensor.

A tapered single-mode coreless single-mode (SCS) structure with high sensitivity for sensing refractive index is described. In order to achieve high specificity of optical biosensors, here enzyme capsulation film was achieved by embedding urease in zeolitic imidazolate framework (ZIF-8/urease) through in situ growth approach on the coreless fibers. Determination of urea is achieved through online monitoring of its binding to the urease in zeolitic imidazolate framework. Refractive index change result in wavelength shifts of the optical fiber biosensor. The resonance wavelength exhibits a good linear relationship with urea concentration in the range of 1 to 10mM with detection limit of 0.1mM and sensitivity of 0.8mM/RIU (refractive index unit)if operated with broadband light ranging from 1525nm to 1590nm. Final assessment of optical biosensor in real sample was performed where excellent performance interms of sensitivity and selectivity was observed. Schematic representation of experimental setup and mechanism for urea detection. A tapered single-mode coreless single-mode (SCS) structure is placed between a broadband light source ranging (BBS) and optical spectrum analyzer (OSA). ZIF-8/urease composites are applied as a recognition layer for urea detection.

A dual channel self-compensation optical fiber biosensor based on coupling of surface plasmon polariton

We propose a dual-channel fiber-optic biosensor based on electronic field coupling between surface plasmon resonance (SPR) and localized surface plasmon resonance (LSPR). One sensing channel is coated with a bilayer of graphene oxide/Au, whose surface is modified with goat anti-human immunoglobulin G (IgG) to detect human IgG labeled with Au nanoparticles (Au NPs). The graphene oxide film in the region of the coupled electric fields increases the loading of biomolecules on the sensor surface and the immunological response. This sandwich structure can make full use of the coupled electric field excited by Au film and Au NPs, compared to the traditional LSPR sensor. The other sensing channel is coated only with Ag film as a reference channel to eliminate measurement error caused by non-specific binding and temperature cross-sensitivity. We numerically investigate the electric field coupling strength of SPR/LSPR and conducted corresponding experiments. The sensor had a high refractive index sensitivity with 13,592 nm/RIU and limit of detection of human IgG can be reduced to 15 ng/mL, which is 15.3 times lower than that of conventional SPR sensors. The proposed biosensor has sensing superiorities of high sensitivity, accuracy and temperature insensitive.

An Optical Microfiber Biosensor for CEACAM5 Detection in Serum: Sensitization by a Nanosphere Interface

The detection of carcinoembryonic antigen (CEA)-related cell adhesion molecules 5 (CEACAM5) is significant in cancer prewarning. Early diagnosis can effectively alleviate the danger of cancer. Point-of-care testing (POCT) has become a competitive technology for early detection. Fiber optic biosensors have great potential as POCT tools. However, their limits of detection (LODs) are not sufficient to afford ultralow concentration detection at the early stage. Herein, this work presents an optical microfiber sensor functionalized by a polystyrene@gold nanosphere (PS@Au nanosphere) interface for a synergistic sensitization effect to detect the ultralow CEACAM5 concentrations in serum at the early stage. The sensor's LOD achieves 3.54 × 10-17 M in pure solution and 5.27 × 10-16 M in serum, with the sensitization effect coupled with surface area enlargement and electromagnetic enhancement of interface. This LOD is about 6 orders of magnitude lower than that of current methods. It can be employed to detect the biomarkers at ultralow concentrations present in serum in the early stages of cancer. As the interfacial synergistic sensitization strategy is suitable for refractive index (RI)-based optical transducers, this work provides new opportunities to employ fiber optic biosensors as effective POCT tools.

Detection of Diabetes using Biosensors

Diabetes is the widespread disease in the world. During the last few decades there is a huge increase in the number of diabetic patients. Biosensor is a device which is used to detect diabetes. It converts biological reading into electrical pursuing that helps the patients to predict their diabetic levels. It consists of a biological recognition element and a chemical sensor. They are high-technology tracking tools that measures sugar levels in a quick, highly sensible fashion. We mainly focus on the glucose-oxidase biosensor which uses machine learning techniques and regression methods. Detection of diabetes can be done in many forms like with a radiofrequency biosensor chip, optical fiber biosensor, micro-fluidic biosensor. Optical biosensor is placed in contact lens to detect glucose levels within the tears and give the accurate prediction. There were some early versions of glucose-sensing devices. There are different existing techniques for the detection. But the preferred method is using the continuous glucose observing system. This method offers a good control of diabetes by using real time data. However, there are few provokes identified with the accomplishment of precise and dependable glucose observing. Further consistency and improvements in the development of biosensors to meet their goals are required.

Hydrophobin HGFI–based fibre-optic biosensor for detection of antigen–antibody interaction

Abstract A compact S-tapered fibre biosensor functionalised with class I hydrophobin HGFI found in Grifola frondosa has been proposed for the first time to accrue label-free detection of reaction between goat–anti-rabbit immunoglobulin G (IgG) (GAR, antibody) and rabbit–anti-hemagglutinin IgG (R, antigen). The HGFI nanolayer self-assembled on fibre surface provides a distinguished analytical platform to implement biocompatible binding owing to its prominent amphiphilicity and remarkable optical as well as biochemical properties. Water contact angle measurements, atomic force microscopy, and immunofluorescence assay are utilised to characterize the modification properties of siliconised substrate surface with HGFI. Functionalisation of the S-tapered fibre is achieved by exploiting self-assembly of HGFI and immobilisation of GAR for specific R detection. HGFI with a concentration of 300 μg/ml allows the formation of a self-assembled amphipathic film on fibre surface, which can adsorb antibody smoothly with such desirable merits as ease of operation, fast response, good stability, good repeatability, and no side effects. Immunoassay experiments are conducted based on dip wavelengths interrogation of the interferometric transmission spectrum. In this study, we propose a novel antigen detection scheme, which could be extended for the detection of other biomolecules owing to its high integration, good specificity, real-time detection, and simple detection scheme.

Development of an enzyme-based fiber optic biosensor for detection of haloalkanes

Purpose The main purpose of this study is to demonstrate the development of an enzyme-based sensor for haloalkane detection. Haloalkane is a toxic compound that is found as genotoxic impurities in pharmaceutical products and contaminants in waste. The need to investigate the genotoxic level in pharmaceutical manufacturing is very crucial because of its toxicity effects on human health. The potential of mini protein as an alternative bioreceptor was explored with the aim to be more effective and stable under extreme conditions. Design/methodology/approach Mini proteins of haloalkane dehalogenase (HLD) were computationally designed and experimentally validated. Tapered multimode fiber (TMMF) was bio-functionalized with a bioreceptor either native (positive control) or mini protein. The absorbance-based sensor resulting from the binding interaction of mini protein with haloalkane was monitored through a wavelength range of 200-1,300 nm. Findings An increment of the UV absorption is observed at 325 nm when haloalkane interacted with the immobilized bioreceptors, native or mini protein. Both biosensors displayed a continuous response over the range of 5-250 µM haloalkane. They also had the capability to detect haloalkanes below 1 min and with an operational stability of up to seven days without significant loss of sensitivity. Practical implications The results indicate the potential viability of the enzyme HLD-based sensor to monitor the existence of haloalkane in both pharmaceutical and environmental products. Originality/value The paper describes an outcome of experimental work on TMMF-based biosensor coated with HLD for label-free haloalkane detection. Mini protein can be used as an effective bioreceptor with some structural modification to improve functionality and stability.

A novel optical fiber glucose biosensor based on carbon quantum dots-glucose oxidase/cellulose acetate complex sensitive film

A novel optical fiber glucose biosensor based on fluorescent carbon quantum dots (CQDs)-glucose oxidase (GOD)/cellulose acetate (CA) complex sensitive film was fabricated, in which the dip-coating method was adopted to immobilize the CQDs-GOD/CA complex sensitive film onto the end face of the optical fiber. The surface morphology, microstructure and optical performances of the sensitive film were characterized by field emission scanning electron microscope (FESEM), atomic force microscope (AFM), Zeiss Axiovert 25 inverted microscope, Fourier transform infrared spectroscopy (FTIR), Ultraviolet–visible spectrophotometer and fluorescence spectrophotometer, respectively. The developed fiber-optic biosensor exhibits high sensitivity and repeatability for continuous online detection of low concentration glucose, allowing visualization of real-time glucose fluctuations over a period of time. The change ratios in fluorescence intensity of the biosensor are linear with glucose concentration in various ranges including micromole and nanomole levels, and the relationship between relative fluorescence intensity ratio and glucose concentration complies well with the modified Stern-Volmer equation in the range of 10–200 μmol/L with the detection limit of 6.43 μM, and in the range of 10–100 nmol/L with the detection limit of 25.79 nM, respectively.

Back Cover: Diaphragm‐based optical fiber sensor for pulse wave monitoring and cardiovascular diseases diagnosis (J. Biophotonics 10/2019)

A wearable device based on fiber optic biosensor for high‐precision radial pulse wave monitoring and diagnosis is proposed and demonstrated in this article. Owing to the high sensitivity of the tiny fiber tip with aluminum diaphragm assembled in the sportswristband, weak acoustic signal induced by arterial pulse can be high‐fidelity recovered and then quantitatively analyzed for clinical diagnosis, which is promising in early cardiovascular diseases indicating.Further details can be found in the article by Jingyi Wang, Kewei Liu, Qizhen Sun, et al. (e201900084). image

Modeling of a fiber optic SPR biosensor employing Tin Selenide (SnSe) allotropes

We report an unique design of a fiber optic SPR biosensor in this study utilizing two-dimensional (2D) Tin Selenide (SnSe) allotropes not revealed before. Due to enhanced optical characteristics with 2D graphene-like structure of monolayer SnSe, recently it is getting much attraction by the researchers to use as a biomolecular recognition element (BRE) in sensor design. Sensitivity of the proposed fiber optic sensor with three sorts of monolayer allotropes of SnSe (α-SnSe, δ-SnSe and ε-SnSe) as a BRE is analyzed through wavelength interrogation scheme for sensing application. Results show that sensors with α-SnSe, δ-SnSe, and ε-SnSe exhibit sensitivities of 3225 nm/RIU, 3300 nm/RIU and 3475 nm/RIU respectively. It is obvious that proposed sensor with improved sensitivity outperforms the conventional Ag-only based sensors having poor sensitivity of 1800 nm/RIU. Thus the proposed SnSe allotropes can be reasonable alternate of conventional BRE to design extremely high sensitive fiber optic SPR biosensors for DNA hybridization.

Design and Performance Perspectives on Fiber Optic Sensors With Plasmonic Nanostructures and Gratings: A Review

This paper presents a sharp review of the current state-of-the-art related to the fiber optic sensors with (i) gratings (namely, fiber Bragg gratings, i.e., FBG and long period fiber gratings, i.e., LPG) and (ii) plasmonic nanostructures (metallic/non-metallic gratings, corrugations, and arrays). The objective of this review is to highlight the importance of these areas in terms of their high sensing performance and the great potential they possess for developing plasmonics-based fiber optic chemical and biosensors with even higher levels of performance in the future. In line with the above objectives, the selected salient works are revisited while beginning with the earliest works on general fiber SPR sensors as well as both the above-mentioned areas. In this process, the review makes a thoughtful attempt to spot the possible future scope and emergent themes in these research areas. The review will be able to provide adequate directives to the researchers willing to take up these areas as their future endeavors.

A disposable fiber optic SPR probe for immunoassay

Immunoassay can be divided into two aspects, one is immobilization of antibodies for the efficient detection of corresponding antigens, and the other is immobilization of antigens to search for antibodies which work against them. In this paper, we demonstrated these two aspects of immunoassay by using the disposable fiber optic biosensors based on surface plasmon resonance (SPR) through surface decoration with half-antibody fragments, which has been scarcely ever reported to the best of our knowledge. We first fabricated the fiber optic SPR biosensor which consists of one gold film coated single-mode fiber sandwiched by two multimode fibers. Then, we decorated the fiber optic SPR biosensors with antibody fragments and antigen fragments, respectively, and compared the specific detection performances of these two kinds of sensors. After surface decoration with half-antibody fragments, the antigen-decorated fiber probe has a demonstrated sensitivity and limit of detection of 0.9771nm/(μg/mL) and 0.1 μg/mL, respectively, which improves by 10 times compared with the performance of the antibody-decorated fiber probe. Additionally, the selective detection results indicate that our proposed biosensor can be employed as a reliable antigen detector or an effective antibody filter. Our proposed sensor has the advantages of miniaturization, low cost, simple usage, label-free detection, high efficiency and sensitivity, and can effectively avoid cross-contamination caused by reuse. Given the reliable and clean detection method for immunoassay, our work should open a new window for the utilization of miniaturized fiber optic sensors in biochemical sensing.

Cu/ITO-Coated Uncladded Fiber-Optic Biosensor Based on Surface Plasmon Resonance

A surface plasmon resonance (SPR)-based fiber-optic biosensor with bi-layers (copper, ITO) has been experimentally proposed and demonstrated. Benefitting from its high refractive index and unique optoelectronic properties, the additional ITO layer immobilized onto the Cu film can significantly improve its sensing performance. A sensitivity of 4583.4 nm/RIU (refractive index unit) was achieved, with a large enhancement in the figure of merit (FOM) by 61.6% compared with the sample without the ITO layer. Furthermore, the proposed SPR-based biosensor exhibits a bovine serum albumin (BSA) solution concentration sensitivity of 1.907 nm/(mg/mL) and a detection limit of $5.70\,\times \, 10^{-7}$ mg/mL. Significantly, this biosensor shows a sub-microliter-dose sensitivity, with promising biochemical applications such as DNA hybridization, cancer screenings, medicine examination, and environmental engineering.

Diaphragm-based optical fiber sensor for pulse wave monitoring and cardiovascular diseases diagnosis.

Arterial pulse wave has been considered as a vital sign in assessment of cardiovascular diseases. Noninvasive pulse sensor with compact structure, immunity to electro-magnetic interference and high sensitivity is the research focus in recent years. While, optical fiber biosensor is a competitive option to meet these needs. Here, a diaphragm-based optical fiber pulse sensor was proposed to achieve high-precision radial pulse wave monitoring. A wearable device was developed, composed of a sports wristband and an aluminum diaphragm-based optical fiber sensor tip of only 1 cm in diameter, which was highly sensitive to the weak acoustic signal. In particular, coherent phase detection was adopted to improve detection signal-to-noise ratio, so as to recover the high-fidelity pulse waveforms. A clinical experiment was carried out to detect and morphological analyze the pulse waveforms of four subjects, the results of which preliminarily demonstrated the feasibility of pulse diagnosis method. The proposed pulse fiber sensor provides a comfortable way for pulse diagnosis, which is promising in early cardiovascular diseases indicating.

A highly selective LSPR biosensor for the detection of taurine realized on optical fiber substrate and gold nanoparticles

Abstract In the current study, we report an enzyme based fiber optic biosensor utilizing the localized surface plasmon resonance (LSPR) of gold nanoparticles for the detection of taurine in the concentration range of 0–1 mM. For probe fabrication, gold nano-particles are decorated on an unclad portion of multimode optical fiber, and taurine dioxygenase enzyme is immobilized over them. The presence of taurine and its co-reactants alpha-ketoglutarate and oxygen in the vicinity of the probe activates the immobilized enzyme which elicits the chemical reaction that gets manifested in the form of refractive index change in the surrounding of gold nanoparticles. This changes the absorbance spectrum of the nanoparticles recorded at the output end of the fiber probe. The absorbance spectrum changes in terms of absorbance and peak absorbance wavelength. A change of 0.0115 in absorbance value is obtained for the change in taurine concentration from 0 to 1 mM. The limit of detection and the sensitivity of the sensor are found to be 53 µM and 0.0190 AU/mM, respectively. The sensor response is found to be stable and selective along with good repeatability. Being fabricated on optical fiber substrate, the sensor possesses the inherent advantages like online and remote monitoring of taurine along with immunity to electromagnetic noise. Moreover, the reported sensor has simple operation and is low in cost.