Detection Of Biological Analytes Research Articles

Surface Blocking-Based Potentiometric Biosensor for Detection of E. coli ATCC 15597 Using Phage MS2 as a Receptor.

Nowadays, using a potentiometric ion sensor to achieve detection of biological analytes is still a big challenge, since these analytes usually do not yield a measurable ion signal. To address this challenge, a simple and robust potentiometric sensing protocol based on a delayed Nernstian response is proposed for the label-free detection of biological analytes. The proposed sensor platform is composed of two layers: the surface recognition layer and the indicator-ion-selective electrode (ISE) membrane layer. It is based on a surface blocking mechanism in which the surface recognition interactions between the surface recognition element and the target can impede the diffusion of the indicator ion from the aqueous phase to the sensing membrane phase to reach the final Nernstian-response equilibrium, thus resulting in a delayed potential change. Such a potential change could be used to measure the concentration of a biological target in the sample. Thus, a sensing system was designed by using phage MS2, its host bacterium Escherichia coli ATCC 15597(abbreviated as E. coli H), and a solid-contact butyrylcholine ISE as a surface recognition element, a target, and an indicator electrode, respectively. This new concept offers a simple, sensitive, and extremely selective potentiometric method for detection of E. coli H with a detection limit of 100 CFU mL-1. It can be expected that the present approach may pave the way to using ISEs to detect various important nonionic biological targets in clinical and environmental applications.

Multispectral nano-cavity-based plasmonic refractive index sensor: Higher bulk and surface sensitivity for detection of biological analytes

In this paper, a Nano-cavity based multispectral plasmonic refractive index sensor for prostate-specific antigen (PSA) detection was investigated. The proposed structure includes two cavities in the form of a T and E shape inside a metal layer. The validity of the findings was verified through the use of the 3D finite difference time domain (FDTD) method. The identification of biomolecules is difficult for conventional biosensors in which there is a very limited amount of analyte, other metrics should be used. In most cases, there is enough analyte to completely cover the sensing surface. Here, in addition to bulk sensitivity, the surface sensitivity was analyzed. The proposed structure has three resonance modes. According to our findings, the designed structure has a bulk sensitivity of 958.3 nm/RIU for the third mode (mode III), 550 nm/RIU for the second mode (mod II), and 637.1 for the first mode (mode I). Having three resonance modes makes this structure a suitable option for use in multispectral applications. The surface sensitivity of 429.4, 457.6, and 465.5 nm/RIU was obtained for surface layer thicknesses of 3.5 nm, 5 nm, and 6.5 nm, respectively. Our results show the proposed structure has good potential in different biological applications.

Wearable, disposable and non-enzymatic fluorescence nanosensor for monitoring sweat glucose through smartphone

The promise of non-invasive health monitoring has fuelled the development of wearable biosensors for in situ detection of biological analytes in sweat. This paper presents a new fluorescent nanosensor probe based on boric acid functionalized and heteroatom doped carbon quantum dots (CQDs) embedded in paper-based analytical devices and integrated with a hydrophilic cotton thread-based microfluidic channel for the development of a flexible, wearable, biocompatible, and biodegradable sweat sensor for real-time measurement of sweat glucose concentration via smartphone readout. The morphological, physiochemical, compositional, crystallinity, and optical properties of nanosensors were extensively investigated. CQD particle sizes were found to be widely dispersed, ranging from 2.6 to 7.1 nm, with an average diameter of 4.38 nm. A dual response via fluorescence and colorimetric change was demonstrated for on-site sweat glucose monitoring using a smartphone camera to capture images in RGB (red, green, and blue) format and analyse them simultaneously by a customized android app, with quantitative results displayed on the smartphone. The limit of detection value for in situ measurement of sweat glucose concentration was 1.40 to 2.00 μM (25.25 to 36.13 μg/dL) and the limit of quantification value was 4.67 to 6.69 μM (84.16–120.44 μg/dL) in the pH range of 4.5 to 7.5. The developed sensor's performance metrics were validated using a standard clinical technique, which indicates strong correlation between two methods with Pearson correlation coefficient values of 0.83 and 0.80 for non-diabetic and type- II diabetes patients, respectively. Besides, interference, spike, and recovery studies were carried out with recovery rates ranging from 96.5 to 105.8 %, demonstrating good repeatability and reproducibility. Furthermore, feasible fluorescence quenching processes have been explored. In addition, the disposable and biodegradable nature of the nanosensor probe was studied by throwing it into the soil in the natural environment, where it dissolves almost spontaneously after three weeks.

Introduction to the feature issue: Advances in Optical Biosensors for Biomedical Applications

The feature issue of Biomedical Optics Express titled “Advances in Optical Biosensors for Biomedical Applications” presents a comprehensive collection of cutting-edge optical biosensor research. With the growing demand for sensitive, label-free, and real-time detection of biological analytes, optical biosensors have emerged as important devices in a wide range of biomedical applications, including medical diagnostics, bioanalysis, and personalised healthcare. This collection of 26 papers highlights recent advances and innovations in the development, design, and implementation of optical biosensors. The feature issue serves as an opportunity for disseminating ground-breaking findings, promoting new ideas, and inspiring further developments in optical biosensors for medical applications. The authors provide breakthrough technology, innovative approaches, and practical clinical applications that have the potential to revolutionize healthcare and biomedical research.

Nanoplasmonic Affinity Analysis System for Molecular Screening Based on Bright‐Field Imaging

AbstractConsidering the improved detection of biological analytes for affinity analysis is highly desirable, a metasurface plasmon resonance (Meta‐SPR)‐based imaging system, incorporating a localized SPR sensing platform with different microfluidic systems and employing simple bright‐field imaging, is established in this study. This system enables low‐level analyte concentration analysis, ranging from 100 pm to 100 nm, with the real‐time removal of nonspecific binding signals within the same device field of view. Combined with microfluidic systems and microdroplet spotting, it is possible to automatically measure the kinetic curves of a sample at ten concentration gradients or detect the specific responses of multiple samples in a single experiment simultaneously. This system can inexpensively and conveniently achieve complex detection functions, demonstrating an innovative breakthrough in sensor detection.

Carbohydrate polymer-supported metal and metal oxide nanoparticles for constructing electrochemical sensors

Metal- and metal oxide-carbohydrate polymers are considered a promising tool for electrochemical detection of biological analytes and water pollutants.

Analysis of a highly temperature-sensitive gold-coated plasmonic biosensor for analyte detection

A temperature-sensitive gold coated PCF-based surface plasmon resonance (SPR) biosensor was examined for detecting analytes based on their refractive indices. The proposed sensor attained maximum amplitude sensitivities (AS) of 1432 RIU−1 and 1291 RIU−1, wavelength sensitivities (WS) of 13,500 nm/RIU and 13,000 nm/RIU in X and Y- polarized mode individually in RI spectrum of 1.34–1.4. Furthermore, the proposed sensor produced ultimate figure of merit (FOM) values of 546.93 RIU−1 and 521.4601 RIU−1 in x and y polarization modes. High birefringence of 1.5 × 10−3 was also computed for the suggested sensor. Additionally, the proposed sensor shows high temperature sensitivity of 4.5833 nm/°C with a comparable resolution of 2.18××10−2 °C and a maximum FOM value of 0.101 °C−1 in the detection range of −114 °C to 78 °C in the presence of ethanol as a sensing medium. The reported sensor therefore can be considered as a notable solution for any chemical or biological analytes detection.

Effect of metal coordination in modulating the binding interaction of an arylimidazole-derived organic chromophore with lipase

The development of reliable fluorescent probes for selectively and sensitively detecting particular analytes in biological systems, which can acid in better understanding the roles in their native contexts. Metal-complex dyes represent a family of structures that have attracted extensive attention in broad applications owing to their unique advantages, such as stable photophysical and electromagnetic properties, as well as good biocompatibility. In this work, we synthesized and characterized a fluorescent probe called THS, which untilizes diphenylamine (DPA) as a metal chelator and an arylimidazole-derived organic chromophore as a fluorescence signal reporter. A comparative assessment of responsive THS and its Zn(II) complex to lipase, an enzyme that breaks down fats, has been performed. We have evidenced the complexation of Zn(II) improved the sensing stability, signal-to-noise ratio (SNR), and selectivity of THS toward lipase. Importantly, we successfully applied the THS-Zn(II) complex to detect lipase in serum samples. This work provides an approach for fabricating simple and effective metal complex-based fluorescence probes and a promising application for the detection of biological analytes.

Susceptible Plasmonic Photonic Crystal Fiber Sensor with Elliptical Air Holes and External-Flat Gold-Coated Surface

This paper proposes and analyzes a simple surface plasmon resonance (SPR)-based elliptical air hole photonic crystal fiber (PCF) sensor. The fiber structure comprises an analyte channel of the fiber surface coated with a gold layer on the flat surface and the fiber’s external surface. Numerical simulations are conducted using the finite element method (FEM) with an external sensing approach. We found that the thickness of plasmonic material (Au) is the most crucial factor that affects the full width at half maximum (FWHM) and confinement loss amplitude. We also demonstrated that the proposed elliptical air hole SPR-PCF is superior to circular air hole SPR-PCF in terms of confinement loss and FWHM. According to the wavelength interrogation technique, the simulation results show that the designed SPR-PCF sensor can attain a maximum sensitivity of 116,500 nm/RIU and a resolution of 8.58 × 10−7 RIU (RIU: refractive index unit) for the analyte RI of 1.395. We believe the proposed SPR-PCF sensor can be a potential candidate for biomolecular and biological analyte detection.

Strategies for Enhancing the Sensitivity of Electrochemiluminescence Biosensors.

Electrochemiluminescence (ECL) has received considerable attention as a powerful analytical technique for the sensitive and accurate detection of biological analytes owing to its high sensitivity and selectivity and wide dynamic range. To satisfy the growing demand for ultrasensitive analysis techniques with high efficiency and accuracy in complex real sample matrices, considerable efforts have been dedicated to developing ECL strategies to improve the sensitivity of bioanalysis. As one of the most effective approaches, diverse signal amplification strategies have been integrated with ECL biosensors to achieve desirable analytical performance. This review summarizes the recent advances in ECL biosensing based on various signal amplification strategies, including DNA-assisted amplification strategies, efficient ECL luminophores, surface-enhanced electrochemiluminescence, and ratiometric strategies. Sensitivity-enhancing strategies and bio-related applications are discussed in detail. Moreover, the future trends and challenges of ECL biosensors are discussed.

Facile Microwave Assisted Synthesis of Silver Nanostars for Ultrasensitive Detection of Biological Analytes by SERS.

We report a very simple, rapid and reproducible method for the fabrication of anisotropic silver nanostars (AgNS) that can be successfully used as highly efficient SERS substrates for different bioanalytes, even in the case of a near-infra-red (NIR) excitation laser. The nanostars have been synthesized using the chemical reduction of Ag+ ions by trisodium citrate. This is the first research reporting the synthesis of AgNS using only trisodium citrate as a reducing and stabilizing agent. The key elements of this original synthesis procedure are rapid hydrothermal synthesis of silver nanostars followed by a cooling down procedure by immersion in a water bath. The synthesis was performed in a sealed bottom flask homogenously heated and brought to a boil in a microwave oven. After 60 s, the colloidal solution was cooled down to room temperature by immersion in a water bath at 35 °C. The as-synthesized AgNS were washed by centrifugation and used for SERS analysis of test molecules (methylene blue) as well as biological analytes: pharmaceutical compounds with various Raman cross sections (doxorubicin, atenolol & metoprolol), cell lysates and amino acids (methionine & cysteine). UV-Vis absorption spectroscopy, (Scanning) Transmission Electron Microscopy ((S)TEM) and Atomic Force Microscopy (AFM) have been employed for investigating nanostars’ physical properties.

Machine Learning for Carbon Nanotube Optical Sensors

Perception-based machine learning platforms, modeled after the complex olfactory system, can isolate individual signals through an array of relatively nonspecific receptors. Each receptor captures certain features, and the overall ensemble response is analyzed by the neural network in our brain, resulting in perception. Previous attempts to develop perception-based sensing platforms include “electronic nose” technologies for gas sensing, based on conducting polymers, DNA-decorated field-effect transistors, and other technologies based on protein recognition using simple data analytic techniques. We developed single-walled carbon nanotube (SWCNT)-based sensor arrays wherein the optical responses of the nanotubes were used to train machine learning models. Due to the existence of several mechanisms of optical modulation of SWCNTs, as well as multiple carbon nanotube species with differing bandgaps, and the increasing number of moieties that can be used for colloidal suspension and functionalization, new methods in data analytics can be used to facilitate selective recognition of bioanalytes to detect and process multi-parametric spectroscopic fingerprints. These methods can improve the detection of biological analytes and to diagnose diseases.

Plasmonic sensor realized on metal-insulator-metal waveguide configuration for refractive index detection

In this work, a plasmonic sensor established on metal-insulator-metal waveguide configuration is proposed and numerically investigated for biosensing applications. The spectral and sensing characteristics of the device are examined via the two-dimensional finite element method. Sensitivity (Sbulk) and figure of merit (FOM) are two important parameters that are considered to determine the device performance. The Sbulk of the device is considered as a ratio between the change in resonance wavelength and change in the ambient refractive index. Whereas FOM is the ratio of Sbulk to full width at half maximum. The Sbulk and FOM offered by the device are ~825.7 nm/RIU and ~13.14, respectively. This work can provide a guideline for the realization of highly sensitive plasmonic sensing devices. Full Text: PDF ReferencesN.L. Kazanskiy, S.N. Khonina, M.A. Butt, "Plasmonic sensors based on Metal-insulator-metal waveguides for refractive index sensing applications: A brief review", Physica E: Low-dimensional systems and Nanostructures 117, 113798 (2020). CrossRef D. Xiang, W. Li, "MIM plasmonic waveguide splitter with tooth-shaped structures", Journal of Modern Optics 61, 222-226 (2014). CrossRef M.A. Butt, S.N. Khonina, N.L. Kazanskiy, "Ultra-short lossless plasmonic power splitter design based on metal–insulator–metal waveguide", Laser Physics 30, 016201 (2020). CrossRef J. Park, S. Lee, B. Lee, "Polarization Singularities in the Metal-Insulator-Metal Surface Plasmon Polariton Waveguide", IEEE Journal of Quantum Electronics 46, 1577-1581 (2010). CrossRef M. T. Hill, M. Marell, E. S. P. Leong, B. Smalbrugge, Y. Zhu, M. Sun, P. J. V. Veldhoven, E. J. Geluk, F. Karouta, Y-S. Oei, R. Notzel, C-Z. Ning, M. K. Smit, "Lasing in metal-insulator-metal sub-wavelength plasmonic waveguides", Optics Express 17, 11107-11112 (2009). CrossRef A. Udupi, S. K. Madhava, "Plasmonic Coupler and Multiplexer/Demultiplexer Based on Nano-Groove-Arrays", Plasmonics 16, 1685-1692 (2021). CrossRef Y-F. C. Chau, C-T. C. Chao, H-P. Chiang, "Ultra-broad bandgap metal-insulator-metal waveguide filter with symmetrical stubs and defects", Results in Physics 17, 103116 (2020). CrossRef H. Bahri, S. Mouetsi, A. Hocini, H.B. Salah, "A high sensitive sensor using MIM waveguide coupled with a rectangular cavity with Fano resonance", Optical and Quantum Electronics 53, 332 (2021). CrossRef S.N. Khonina, N.L. Kazanskiy, M.A. Butt, A. Kazmierczak, R. Piramidowicz, "Plasmonic sensor based on metal-insulator-metal waveguide square ring cavity filled with functional material for the detection of CO2 gas", Optics Express 29, 16584 (2021). CrossRef M.A. Butt, S.N. Khonina, N.L. Kazanskiy, "Plasmonics: A Necessity in the Field of Sensing-A Review (Invited)", Fiber and Integrated Optics 40, 14-47 (2021). CrossRef M.A. Butt, A. Kazmierczak, N.L. Kazanskiy, S.N. Khonina, "Metal-Insulator-Metal Waveguide-Based Racetrack Integrated Circular Cavity for Refractive Index Sensing Application", Electronics 10, 1419 (2021). CrossRef N.L. Kazanskiy, S.N. Khonina, M.A. Butt, A. Kazmierczak, R. Piramidowicz, "A Numerical Investigation of a Plasmonic Sensor Based on a Metal-Insulator-Metal Waveguide for Simultaneous Detection of Biological Analytes and Ambient Temperature", Nanomaterials 11, 2551 (2021). CrossRef I. Tathfif, A.A. Yaseer, K.S. Rashid, R.H. Sagor, "Metal-insulator-metal waveguide-based optical pressure sensor embedded with arrays of silver nanorods", Optics Express 29, 32365-32376 (2021). CrossRef P.D. Sia, "Overview of Drude-Lorentz type models and their applications", Nanoscale Syst. Math. Model. Theory Appl. 3, 1-13 (2014) CrossRef M.A. Butt, N.L. Kazanskiy, "Nanoblocks embedded in L-shaped nanocavity of a plasmonic sensor for best sensor performance", Optica Applicata LI, 109-120 (2021). CrossRef S. Khani, M. Hayati, "An ultra-high sensitive plasmonic refractive index sensor using an elliptical resonator and MIM waveguide", Superlattices and Microstructures 156, 106970 (2021). CrossRef F. Chen, J. Li, "Refractive index and temperature sensing based on defect resonator coupled with a MIM waveguide", Modern Physics Letters B 33, 1950017 (2019). CrossRef M. Rahmatiyar, M. Danaie, M. Afsahi, "Employment of cascaded coupled resonators for resolution enhancement in plasmonic refractive index sensors", Optical and Quantum Electronics 52, 153 (2020). CrossRef M.A. Butt, S.N. Khonina, N.L. Kazanskiy, "A multichannel metallic dual nano-wall square split-ring resonator: design analysis and applications", Laser Physics Letters 16, 126201 (2019). CrossRef

Fully printed and flexible multi-material electrochemical aptasensor platform enabled by selective graphene biofunctionalization

The demand for flexible biochemical sensors has increased with advances in computational functionality and wireless communication. Advances in materials science and biochemistry have enabled the development and fabrication of biosensors for selective detection of biological analytes leveraging ink-printed technologies, including in flexible form-factors. However, despite these advances, minimal effort has been devoted to translating the multi-material, three-electrode electrochemical cell, which is widely regarded as the standard for laboratory-scale studies, into a flexible form-factor for use in immunosensors, especially in a manner that is compatible with rapid and scalable additive manufacturing. Here, we report a fully printed and flexible electrochemical non-enzymatic immunosensor platform that integrates four chemically compatible inks and a non-covalent, two-step biofunctionalization scheme. The robustness of the platform is demonstrated using a model aptasensor that enables lysozyme detection using both electrochemical impedance spectroscopy and square wave voltammetry. The flexible, fully ink-printed aptasensor shows competitive performance to commercially available rod/disc electrodes in a bath cell. Overall, this work establishes a methodology for high-throughput fabrication of robust, flexible, multi-material, three-electrode immunosensors that can be generalized to a range of biosensor applications.

Sensitivity enhancement of a graphene, zinc sulfide-based surface plasmon resonance biosensor with an Ag metal configuration in the visible region

A biosensor based on the modified Kretschmann configuration is proposed here. The sensitivity of the conventional prism-based sensor using angular interrogation is low. To enhance the sensor's performance, layers of zinc sulfide (ZnS) and graphene have been deposited over the metal layer. The angular interrogation technique is used to analyze the performance of the sensor. The thickness of the Ag metal has been optimized. The thickness of the Ag metal is taken as 50 nm because minimum reflectance has been achieved. With the combinations of the four layers of ZnS and one graphene layer, the maximum sensitivity attained is $$292.8^\circ /RIU$$ . Performance parameters such as detection accuracy, FWHM, and quality factor of the sensor have been evaluated as obtained as 0.16 $${\text{ deg}}^{ - 1}$$ , 6.37 $${\text{ deg}}$$ , 46 $$RIU^{ - 1}$$ , respectively. The proposed sensor has potential application in the field of biochemical and biological analyte detection.

Recent development in fluorescent probes based on attacking of double bond and masking of functional group

The works on the procedure of fluorescent sensors for the detection of biological analytes are extremely momentous. Among diverse analytical approaches, fluorescence is the most eye-catching due to its high sensitivity, selectivity, rapidity, robustness, ease of measurement and non-destructive approaches. Herein, we show different fluorescent probes synthesized for estimation and detection of biological analytes (H2S, SO32−/HSO3−, H2O2, HOCl, HNO, ONOO−). These probes were constructed by masking the functional groups (hydroxyl and amino) of fluorophore and formation of active C=C, C=N, C=O and N=N for specific analytes. In this review we concentrate on synthesis of the probe, their photophysical properties and applications to biological studies.

Numerical study of a highly sensitive surface plasmon resonance sensor based on circular-lattice holey fiber

A new design of surface plasmon resonance (SPR) sensor employing circular-lattice holey fiber to achieve high-sensitivity detection is proposed. The sensing performance of the proposed sensor is numerically investigated and the results indicate that our proposed SPR sensor can be applied to the near-mid infrared detection. Moreover, the maximum wavelength sensitivity of our proposed sensor can reach as high as 1.76×104 nm/refractive index unit (RIU) and the maximum wavelength interrogation resolution can be up to 5.68×10−6 RIU when the refractive index (RI) of analyte lies in (1.31, 1.36). Thanks to its excellent sensing performance, our proposed SPR sensor will have great potential applications for biological analytes detection, food safety control, bio-molecules detection and so on.

Detection of single walled carbon nanotube based sensors in a large mammal

High resolution, rapid, and precise detection of biological analytes related to disease and infection is currently the focus of many researchers. Better biosensors could lead to earlier detection, more avenues of intervention, and higher efficacy of therapeutics, which would lead to better outcomes for all patients. One class of biosensors, single walled carbon nanotubes, is unique due to their nanoscale resolution, single molecule sensitivity, and reversibility for long term applications. While these biosensors have been successful in rodent models, to date, no study has shown successful sensor detection in a large animal. In this study, we show the first successful signal detection of single walled carbon nanotube-based sensors in a large mammal model. Using a relatively simple and cost-effective system, we were able to detect signals in nearly 70% of the sheep used in the study, marking an important steppingstone towards the use of SWNT-based sensors for clinical diagnostics.

Low cell concentration detection by Fabry-Pérot resonator with sensitivity enhancement by dielectrophoresis

A yeast cells detection system that combines cell focusing and refractive index measurement is designed to realize label-free, high-resolution cell concentration detection. In our design, Fabry-Pérot (FP) cavity is utilized to conduct the volume RI detection, by which the lightwave can completely permeate the bulky sample solution with strong light-matter interaction, thus it is particularly valuable for ultra-low concentration biological analytes detection. To further improve the sensor sensitivity, dielectrophoresis (DEP) is applied to spatially accumulate the uniformly suspended yeast cells in the light spot region. The final concentration of aggregation was about 50 times the initial state. By using the designed DEP-FP sensing system, a sensitivity of 0.121nm/(amol/mL) (2 × 10−7nm/(cells/mL)) and a resolution of 3.65 × 105 cells/mL is obtained. Due to its top performance for cell concentration detection, this device may have potential applications in molecular cell biology, pharmacology, and biochemistry.

Modelling of plasmonic biosensor temporal response influenced by competitive adsorption and analyte depletion

Highly sensitive detection of biological analytes by plasmonic sensors is based on analyte adsorption, which modifies the effective refractive index (RI) at the medium-sensor interface. The main issue with such sensors is the non-ideal sensor selectivity (manifested in multiple analyte adsorption), while sample depletion (significant at low analyte concentrations) also causes a deviation of the sensor response from the expected time dependence. Mathematical modelling of sensor response, presented in this work, simultaneously tackles these two issues that may cause erroneous interpretation of measurement results. Two mathematical models that address the problem of limited selectivity are utilized to analyse the sensor response: the linear (pseudo-first order) model, commonly used for interpretation of measurements, and the nonlinear (second order) model that takes into account analyte depletion in the sensor chamber. While the nonlinear model has a virtue of generality, the advantages of the linear model are its simplicity and a well-established procedure for the analysis of experimental results. However, the linear model can exhibit large errors in the case of significant analyte depletion. Until now, the influence of analyte depletion on the linear model fidelity has not been studied for multianalyte adsorption. In this paper, we quantify the difference between the RI changes predicted by the two models of two-analyte competitive adsorption, and establish the conditions that justify the use of the linear model. The validity of these conditions is confirmed by numerically solving the exact nonlinear model equations. The conditions enable making an objective decision whether it is safe to use the linear model for detection of ultralow analyte concentrations, or the nonlinear model must be used in order to avoid false-positive/false-negative detection results and analyte quantification errors. The results are applicable in adsorption-based chemical/biological sensing in complex samples, as well as for the new generation single-element multianalyte plasmonic sensors.