Optical Biosensor Research Articles

A polydopamine nanospheres modified fiber optic SPR biosensor for specific detection of C-reactive protein

C-reactive protein (CRP) is a vital inflammatory marker in humans and a key single marker of cardiovascular diseases. In this paper, the concentration of CRP was specifically detected by a polydopamine nanospheres (PDA-NPs) developed surface plasmon resonance (SPR) sensor with high accuracy. PDA-NPs is a self-polymerizing material that can be obtained from dopamine through the mussel adhesion effect. The PDA-NPs (diameter ≈ 100 nm) modified SPR sensor exhibits enhanced refractive index (RI) sensitivity and bio-sensitivity attributed to the large specific surface area and high surface reactivity of the PDA-NPs. The developed sensor demonstrates a RI sensitivity of 2427.68 nm/RIU, presenting a 55.7% increase compared to the raw sensor (RI sensitivity was 1559.08 nm/RIU). Moreover, the developed biosensor is used to detect CRP specifically. The bio-sensitivity reaches 0.09 nm/(µg/mL), while the limit of detection (LOD) reaches 0.22 µg/mL. These findings indicate that the developed biosensor can specifically detect CRP with a low LOD. Therefore, this PDA-NPs modified biosensor has great potential in clinical detection and other bio-detection filed.

Label-Free DNA Detection Using Etched Tilted Bragg Fiber Grating-Based Biosensor.

A label-free-based fiber optic biosensor based on etched tilted Bragg fiber grating (TFBG) is proposed and practically demonstrated. Conventional phase mask technic has been utilized to inscribe tilted fiber Bragg grating with a tilt angle of 10°, while the etching has been accomplished with hydrofluoric acid. A composite of polyethylenimine (PEI)/poly(acrylic acid) (PAA) has been thermally deposited on the etched TFBG, followed by immobilization of probe DNA (pDNA) on this deposited layer. The hybridization of pDNA with the complementary DNA (cDNA) has been monitored using wavelength-dependent interrogation. The reproducibility of the probes has been demonstrated by fabricating three identical probes and their response has been investigated for cDNA concentration ranging from 0 μM to 3 μM. The maximum sensitivity has been found to be 320 pm/μM, with the detection limit being 0.65 μM. Furthermore, the response of the probes towards non-cDNA has also been investigated in order to establish its specificity.

Label-free and highly-sensitive protamine detection by layer-by-layer assembled chitosan/heparin functionalized optical fiber mode interferometer

There is a strong requirement for label-free, selective and rapidly detection of Protamine (PRTM) due to that the PRTM and Heparin (Hep) have been widely used in clinical treatment. Here, an optical fiber interferometer biosensor that functionalized by layer-by-layer electrostatic assembled chitosan/heparin (CS/Hep) is proposed for PRTM detection. Experimental results proved that the refractive index (RI) sensitivity is related to thickness of CS/Hep overlayer, which is a key factor of sensor’s performance. The CS/Hep polyelectrolyte film coating extend its evanescent filed and can also be used as the signal amplification medium for PRTM detection due to the electrostatic interactions between PRTM and Hep. The optimal sensor that coated with 10 bilayers of CS/Hep, demonstrates RI sensitivity of 435.6 nm/RIU as well as ideal stability, and was chosen for PRTM detection. The CS/Hep based biosensor demonstrates a detection limit of 0.48 μg/mL and sensitivity of 0.1238 nm/(μg/mL) in the linear fitting range. Furthermore, the sensor illustrated ideal selectivity in serum samples and well reusability. Overall, the sensor features with high mechanical strength, ease of fabrication, real-time and label-free. This proposed sensor has potential applications for detecting PRTM in clinical applications.

Application of hybrid Au@Ag nanostructures in fiber optic biosensor for rapid detection of C-reactive protein

Elevated levels of C-reactive protein (CRP) in the bloodstream are a well-established marker of systemic inflammation in humans. Research on the application of hybrid plasmon material for optical fiber sensor application to sensitively monitor C-reactive protein concentration based on the hybrid material particles has been proposed in this study. Specifically, Au@Ag nanoparticles are coated onto the optical fiber surface by a self-assembled monolayer using an NH2 bridge. CRP antigens are then immobilized onto the surface of Au@Ag NPs to selectively detect CRP and improve sensor sensitivity. The limit of detection for this fiber sensor is 2.4 × 10−5 mg/L. The selectivity of the sensor was also demonstrated in media containing bovine serum albumin (BSA) and glucose. These findings represent an important step toward the development of biosensors capable of monitoring extremely low concentrations of biomolecules in vivo, thereby supporting early disease detection and diagnosis.

A High-Sensitivity Bimetallic Grating-Coupled Surface Plasmon Resonance Sensor Based on Two-Dimensional Materials

Optical biosensors based on grating-coupled surface plasmon resonance (GCSPR) technology are an important research topic in the field of bio-photonics. This paper presents a high-performance and high-sensitivity nanostructured bimetallic GCSPR sensor based on two-dimensional materials. When designing the sensor, the sensitivity, full width at half peak (FWHM) and dip strength of the absorption peak (DS) were considered comprehensively, and the comprehensive evaluation parameter FOM+ is defined by making improvements on the basis of figure of merit (FOM). The performance of the sensor can be judged more comprehensively. The performance of the sensor was further improved by optimizing the structure of the sensor. An ultra-thin gold layer was added on the surface of the silver-based GCSPR sensor, which solves the problem of the easy oxidation of silver metal. We tried to coat graphene oxide two-dimensional nanomaterials on the surface of the bimetallic sensor, and the sensitivity and FOM+ of the sensor reached 350 deg/RIU and 473.23, respectively. This is a great improvement compared with the GCSPR sensor in a previous study, and it can be improved at least 74.7%. This sensor can measure a variety of biological molecules and biological cells with high sensitivity and performance by detecting the change in the refractive index of the solution to be measured.

Sensor with enhanced performance based on photonic crystal with a defect layer

We propose an improved structure of an optical biosensor based on a photonic crystal with a defect layer, which can detect the concentration of organic contaminants in water by defect mode shift. We investigated 4 types of defective photonic crystals with different arrangements of layers inside the perfect photonic crystals and their impact on the performance of the sensor. The sensitivity and amplitude of defect mode were examined as a function of defect layer thickness. Also, the peculiarities of edge modes in the presence of defect layer were investigated. Finally, we obtained a characteristic equation to determine the wavelengths of defect modes for an arbitrary 1D photonic crystal with an isotropic defect inside.

A Density Functional Theory (DFT) Perspective on Optical Absorption of Modified Graphene Interacting with the Main Amino Acids of Spider Silk.

We investigated the possible adsorption of each of the main building blocks of spider silk: alanine, glycine, leucine, and proline. This knowledge could help develop new biocompatible materials and favors the creation of new biosensors. We used ab initio density functional theory methods to study the variations in the optical absorption, reflectivity, and band structure of a modified graphene surface interacting with these four molecules. Four modification cases were considered: graphene with vacancies at 5.55% and fluorine, nitrogen, or oxygen doping, also at 5.55%. We found that, among the cases considered, graphene with vacancies is the best candidate to develop optical biosensors to detect C=O amide and differentiate glycine and leucine from alanine and proline in the visible spectrum region. Finally, from the projected density of states, the main changes occur at deep energies. Thus, all modified graphene's electronic energy band structure undergoes only tiny changes when interacting with amino acids.

Highly sensitive asymmetric and symmetric cancer sensors with ultra-high-quality factor and resolution power

In the paper, we proposed two new highly sensitive and compact biosensors with ultra-high-quality factors based on the 1-D binary photonic crystal (silicon/air thin layer) with a defect layer. The proposed asymmetric and symmetric biosensors have just a few periods (two to five) on both sides of the defect layer and the normal cell group (INOK) and cancer cells group (YD-10B) are considered for the studies. The effects of different parameters including silicon layer thickness, air layer thickness, defect layer thickness, substrate position, number of periods, and light incident angle are considered in the biosensor operation and the biosensors are optimized based on the sensitivity. The results demonstrate that the sensitivity and defect mode wavelength of the sensors are independent of the substrate position. However, the quality factor and FOM of the sensors significantly depend on the substrate position and they are improved significantly in the symmetric sensor (~ 37% improvement in optimum condition). Also, the high sensitivities of the sensors are maintained over a wide range of silicon and air thicknesses, which is a valuable achievement in the manufacturing process. Furthermore, the sensitivity of the optimized biosensors with a defect layer thickness of 10 microns and only two periods reaches S ~ 2811 nm/RIU which is an excellent sensitivity for an optical biosensor.

Molecular Biomarkers and Recent Liquid Biopsy Testing Progress: A Review of the Application of Biosensors for the Diagnosis of Gliomas.

Gliomas are the most common primary central nervous system tumors, with a high mortality rate. Early and accurate diagnosis of gliomas is critical for successful treatment. Biosensors are significant in the detection of molecular biomarkers because they are simple to use, portable, and capable of real-time analysis. This review discusses several important molecular biomarkers as well as various biosensors designed for glioma diagnosis, such as electrochemical biosensors and optical biosensors. We present our perspectives on the existing challenges and hope that this review can promote the improvement of biosensors.

Perspectives and trends in advanced optical and electrochemical biosensors based on engineered peptides.

With the advancement of life medicine, in vitro diagnostics (IVD) technology has become an auxiliary tool for early diagnosis of diseases. However, biosensors for IVD now face some disadvantages such as poor targeting, significant antifouling properties, low density of recognized molecules, and poor stability. In recent years, peptides have been demonstrated to have various functions in unnatural biological systems, such as targeting properties, antifouling properties, and self-assembly properties, which indicates thatpeptides can be engineered. These properties of peptides, combined with their good biocompatibility, can be well applied tothe design of biosensors to solve the problems mentioned above. This review provides an overview of the properties of engineered functional peptides and their applications in enhancing biosensor performance, mainly in the field of optics and electrochemistry.

A Low-cost Creatinine Biosensor by Differential Optical Signal Readout for the Whole Blood Analysis.

This study developed a low-cost paper-based biosensor for point-of-care (POC) detection of blood creatinine by using differential optical signal readout. Dual-channel photochemical paper-based test strips were fabricated with stackable multilayer films containing pre-immobilized enzymes and reagents for the identification and conversion of creatinine and creatine. Enzyme-linked reactions generated hydrogen peroxide (H2O2), which formed a blue oxidized condensate with aniline derivatives. The color depth was quantified via the differential optical signal of the two channels and positively correlated with the concentration of the analyte. This method was first proposed to address the issue of endogenous interferences in the enzymatic assay of creatinine, greatly improving the detection accuracy. The proposed biosensor was calibrated with spiked blood samples, and achieved a wide detection range of 31-1483 μmol/L, showing superior detection performance to general enzymatic methods, especially in the low concentration range. Creatine interference testing demonstrated that the biosensor could resist the interference of ≤ 300 μmol/L endogenous creatine. It is believed that the proposed optical differential biosensor for blood creatinine could enable to pave the way for a daily monitoring system for renal diseases.Clinical Relevance- This stackable multilayer paper-based biosensor provides an enzymatic colorimetric assay of creatinine in whole blood, which can be read out by the differential optical signal to exclude interference from endogenous creatine.

Optical fiber SPR biosensor with frequency multiplexing compensated laser heterodyne feedback for ultrasensitive detection of fluoroquinolones

The widespread usage and discharge of fluoroquinolones (FQs) have caused negative environmental consequences that can threaten human health. The development of ultrasensitive and simple devices for detection of various FQs is an important requirement. Here, we proposed a novel optical fiber surface plasmon resonance biosensor to achieve the ultrasensitive detection of FQs, in which the frequency-shifted light returned to the laser resonator and stimulated laser heterodyne feedback interferometry to amplify the intensity changes caused by the refractive index (RI) variations. In addition, we further presented a quasi-common path frequency multiplexing compensation method to compensate for the noise of the developed biosensor, resulting in a RI resolution of 1.06 × 10−6 RIU. Besides, the gold nanorods were used to generate localized surface plasmon resonance to further amplify the signal to achieve the ultrasensitive detection. A variety of FQs were detected with ultra-low detection limits, including enrofloxacin (0.61 ng/L), ciprofloxacin (0.54 ng/L), norfloxacin (0.31 ng/L), pefloxacin (0.32 ng/L), and sarafloxacin hydrochloride (0.97 ng/L). With the advantages of high sensitivity, compact size, and remote operation capability, the developed biosensor holds the promise of detecting other antibiotics with universality in hard-to-reach spaces, thus having the potential to demonstrate a promising approach to environmental monitoring.

Proof of principle for a sensitive, real time and label-free detection of poxviruses using optical fiber biosensors

Reliable, affordable, rapid and sensitive point-of-care testing is essential for preparedness towards pandemic viruses that could emerge from zoonoses, laboratory accidents or undercover spread of biological weapons. Although successfully eradicated, variola virus, the causative agent of smallpox, is a category A agent stored in laboratories in USA and Russia, and a possible threat to humanity. Outbreaks of monkeypox worldwide emphasized the need for efficient detection of poxviruses in body fluids and the environment, also considering the fact that the human population is largely unprotected. We produced the ectodomains of vaccinia virus A27, A33 and L1 (highly homologous to smallpox and monkeypox proteins) and established their label-free detection by specific antibodies immobilized by silanization on the surface of optical fiber sensors. Each protein was detected using a fiber-optic sensor based on a ball-resonator assisted by a tilted fiber Bragg grating, which ensure sensitivity > 70 dB/RIU and real-time detection. Fabrication of the sensors was carried out through a CO2 laser splicer, inscribing a spherical tip with ∼500 µm size, and then splicing a previously inscribed tilted grating. The overall spectrum shows a quasi-random pattern due to the ball resonator, modulated by the cladding modes of the grating, in which the intensity of each mode depends on the analyte concentration. Each sensor shows detection limits of 1 fM – 20 pM in serum (<65 aM in phosphate-buffered saline), wide-range response up to 1 μM and a high specificity. This proof of principle for poxvirus detection conceptualizes a general real time pandemic virus preparedness.

Optical Biosensors for the Diagnosis of COVID-19 and Other Viruses-A Review.

The sudden outbreak of the COVID-19 pandemic led to a huge concern globally because of the astounding increase in mortality rates worldwide. The medical imaging computed tomography technique, whole-genome sequencing, and electron microscopy are the methods generally used for the screening and identification of the SARS-CoV-2 virus. The main aim of this review is to emphasize the capabilities of various optical techniques to facilitate not only the timely and effective diagnosis of the virus but also to apply its potential toward therapy in the field of virology. This review paper categorizes the potential optical biosensors into the three main categories, spectroscopic-, nanomaterial-, and interferometry-based approaches, used for detecting various types of viruses, including SARS-CoV-2. Various classifications of spectroscopic techniques such as Raman spectroscopy, near-infrared spectroscopy, and fluorescence spectroscopy are discussed in the first part. The second aspect highlights advances related to nanomaterial-based optical biosensors, while the third part describes various optical interferometric biosensors used for the detection of viruses. The tremendous progress made by lab-on-a-chip technology in conjunction with smartphones for improving the point-of-care and portability features of the optical biosensors is also discussed. Finally, the review discusses the emergence of artificial intelligence and its applications in the field of bio-photonics and medical imaging for the diagnosis of COVID-19. The review concludes by providing insights into the future perspectives of optical techniques in the effective diagnosis of viruses.

A L-glutamine binding protein modified MNM structured optical fiber biosensor based on surface plasmon resonance sensing for detection of L-glutamine metabolism in vitro embryo culture

A surface plasmon resonance (SPR) optical fiber sensor with multimode-coreless-multimode (MNM) structure was developed, which modified by L-glutamine-binding protein (QBP) for detection of L-glutamine (Gln). The QBP was immobilized on the surface of gold films by chemical cross-linking and exhibited a binding affinity for L-glutamine. The conformation of QBP can be changed from the “open” to the “closed”, which led to a red-shift of the SPR peak when QBP bounded to L-glutamine. There was a good linear correlation between is a dependence of the SPR peak on and the concentration of L-glutamine concentration in the range 10–100 μM, with a sensitivity of 10.797nm/log10[Gln] for L-glutamine in the in vitro embryo culture (IVC) medium environment, and the limit of detection (LOD) is 1.187 μM. This QBP-modified MNM structure optical fiber SPR sensor provides a new idea for the developmental potential assessment of embryos in the process of in vitro embryo culture.

Sensing and differentiation between normal flora and pathogenic of E.coli Bacteria using 410 nm diode laser

Abstract: Background: Optical biosensors offer excellent properties and methods for detecting bacteria when compared to traditional analytical techniques. It allows direct detection of many biological and chemical materials. Bacteria are found in the human body naturally non-pathogenic and pathologically, as they are found in other living organisms. One of these bacteria is Escherichia coli (E. coli) which are found in the human body in its natural and pathogenic form. E.coli bacteria cause many diseases, including Stomach, intestines, urinary system infections, and others. The aim of this study: is sensing and differentiation between normal flora and pathogenic E.coli. Material and method: The optical biosensor constructed of a multi-mode – no core- multi mode optical fibre that differentiates between pathogenic and non-pathogenic bacteria of E.coli by measuring the changing for light intensity using source of light 410nm laser diode. Multi-mode - no core - multi-mode optical fibre (MM-NOC-MM) connected to the OSA analyser (HR2000) by means of an adapter and finally connected to a computer to show the results. Results: The intensity of the transmitted light recorded in the case of pathogenic bacteria is less than the intensity of the transmitted light recorded in the case of non-pathogenic bacteria. Conclusion: these results were obtained because of the ideal and better choice of the wavelength of the laser used with its absorption E.coli bacteria.

Optical Biosensor Based on Surface Plasmon Resonance Nanostructure for the Detection of Mycobacterium Tuberculosis Bacteria with Ultra-High Efficiency and Detection Accuracy

Optical Biosensor Based on Surface Plasmon Resonance Nanostructure for the Detection of Mycobacterium Tuberculosis Bacteria with Ultra-High Efficiency and Detection Accuracy

Recent advances in molecular imprinting technique based fiber optic biosensors

Selectivity or specificity of the biosensors is one of the most important requirements. In recent years, molecular imprinting technique (MIT) has become very attractive for specific sensing of analyte because of its several advantages over the bio-receptors (antibodies and enzymes) that are being used. The advantages are better temperature stability, robustness, reproducibility, high affinity, and low cost in addition to the main advantage of selectivity. Surface plasmon resonance (SPR), localized surface plasmon resonance (LSPR), lossy mode resonance (LMR), evanescent wave, fiber gratings and interferometry techniques have been widely exploited for optical sensing of analytes due to their high sensitivity. The integration of MIT with these optical techniques on optical fiber provides several advantages such as compact size, lightweight probe, online monitoring and remote sensing capability. In the last two decades, MIT based fiber optic biosensors have been developed using the aforementioned optical sensing techniques. In this review, we present recent advances in MIT based fiber optic biosensors utilizing various optical techniques. The underlying principles and applications of MIT for specific sensing and an update on recent findings and achievements have been discussed. In addition, the review includes the limitations, challenges and future directions of this technique.

Biosensors – An Insight into the Electrochemical and Optical Biosensors

Biosensors – An Insight into the Electrochemical and Optical Biosensors

Plasmonic Coupling on an Optical Microfiber Surface: Enabling Single-Molecule and Noninvasive Dopamine Detection.

Optical fibers can be effective biosensors when employed in early-stage diagnostic point-of-care devices as they can avoid interference from molecules with similar redox potentials. Nevertheless, their sensitivity needs to be improved for real-world applications, especially for small-molecule detection. This work demonstrates an optical microfiber biosensor for dopamine (DA) detection based on the DA-binding-induced aptamer conformational transitions that occur at plasmonic coupling sites on a double-amplified nanointerface. The sensor exhibits ultrahigh sensitivity when detecting DA molecules at the single-molecule level; additionally, this work provides an approach for overcoming optical device sensitivity limits, further extending optical fiber single-molecule detection to a small molecule range (e.g., DA and metal ions). The selective energy enhancement and signal amplification at the binding sites effectively avoid nonspecific amplification of the whole fiber surface which may lead to false-positive results. The sensor can detect single-molecule DA signals in body-fluids. It can detect the released extracellular DA levels and monitor the DA oxidation process. An appropriate aptamer replacement allows the sensor to be used for the detection of other target small molecules and ions at the single-molecule level. This technology offers alternative opportunities for developing noninvasive early-stage diagnostic point-of-care devices and flexible single-molecule detection techniques in theoretical research.