Detection Of Biochemical Analytes Research Articles

Fluorescence-Based Portable Assays for Detection of Biological and Chemical Analytes.

Fluorescence-based detection techniques are part of an ever-expanding field and are widely used in biomedical and environmental research as a biosensing tool. These techniques have high sensitivity, selectivity, and a short response time, making them a valuable tool for developing bio-chemical assays. The endpoint of these assays is defined by changes in fluorescence signal, in terms of its intensity, lifetime, and/or shift in spectrum, which is monitored using readout devices such as microscopes, fluorometers, and cytometers. However, these devices are often bulky, expensive, and require supervision to operate, which makes them inaccessible in resource-limited settings. To address these issues, significant effort has been directed towards integrating fluorescence-based assays into miniature platforms based on papers, hydrogels, and microfluidic devices, and to couple these assays with portable readout devices like smartphones and wearable optical sensors, thereby enabling point-of-care detection of bio-chemical analytes. This review highlights some of the recently developed portable fluorescence-based assays by discussing the design of fluorescent sensor molecules, their sensing strategy, and the fabrication of point-of-care devices.

Functional microneedles for wearable electronics

AbstractWith an ideal comfort level, sensitivity, reliability, and user‐friendliness, wearable sensors are making great contributions to daily health care, nursing care, early disease discovery, and body monitoring. Some wearable sensors are imparted with hierarchical and uneven microstructures, such as microneedle structures, which not only facilitate the access to multiple bio‐analysts in the human body but also improve the abilities to detect feeble body signals. In this paper, we present the promising applications and latest progress of functional microneedles in wearable sensors. We begin by discussing the roles of microneedles as sensing units, including how the signals are captured, converted, and transmitted. We also introduce the microneedle‐like structures as power units, which depend on triboelectric or piezoelectric effects, etc. Finally, we summarize the cutting‐edge applications of microneedle‐based wearable sensors in biophysical signal monitoring and biochemical analyte detection, and provide critical thinking on their future perspectives.

Metal-organic frameworks (MOFs) as apt luminescent probes for the detection of biochemical analytes.

The detection of active substances in the body is very important for good human health as it gives important insights into the smooth functioning of the body. Most of the conventional materials that can be used as suitable probes require complicated fabrication methodologies, have poor stability and are susceptible to environmental effects. In contrast, metal-organic frameworks (MOFs) offer unique advantages as probes for testing analytes due to their tunable porosity, good specific surface area and ease of modification. Unlike previously reported perspectives/reviews, this perspective focuses on the latest applications of MOFs as detection materials for hydrogen peroxide, various metal ions, hydrogen sulfide, organic small molecules, glutathione, and organic macromolecules such as nucleic acids, and focuses on providing a more detailed mechanism of action. Also, the basic principles of action utilized by this class of materials are discussed.

Microchannel-Embedded D-Shaped Photonic Crystal Fiber-Based Highly Sensitive Plasmonic Biosensor

An improved design of a D-shaped photonic crystal fiber (PCF)-based refractive index (RI) sensor is proposed that uses the surface plasmon resonance phenomenon. The sensor consists of a large semicircular open channel that is inserted at the upside of the D-shaped PCF. A thin plasmonic sensing layer is deposited on the interior surface of the channel to excite the surface plasmon wave that eliminates the requirement of additional effort to fabricate a well-polished sensing layer of the D-shaped sensor. The sensor’s optical properties are numerically explored by the finite element method. The sensor is optimized to detect the RI of biological and biochemical analytes in the range of 1.33 to 1.44, shows spectral sensitivity as high as 63,000 nm/RIU with a spectral resolution of 1.59 × 10−06 RIU, and maximum amplitude sensitivity of 1439 RIU−1 with a resolution of 6.94 × 10−06 RIU. It is also found that the sensor’s linearity parameter is very high with a large figure of merit of about 839. Additionally, the sensor’s fabrication tolerance is studied by varying its structural parameters. Therefore, high sensing parameters with a wide detection range make this microchannel-based D-shaped PCF sensor an appropriate device for the application of biological and biochemical analyte detection.

Metal-Insulator-Metal Waveguide-Based Racetrack Integrated Circular Cavity for Refractive Index Sensing Application

Herein, a novel cavity design of racetrack integrated circular cavity established on metal-insulator-metal (MIM) waveguide is suggested for refractive index sensing application. Over the past few years, we have witnessed several unique cavity designs to improve the sensing performance of the plasmonic sensors created on the MIM waveguide. The optimized cavity design can provide the best sensing performance. In this work, we have numerically analyzed the device design by utilizing the finite element method (FEM). The small variations in the geometric parameter of the device can bring a significant shift in the sensitivity and the figure of merit (FOM) of the device. The best sensitivity and FOM of the anticipated device are 1400 nm/RIU and ~12.01, respectively. We believe that the sensor design analyzed in this work can be utilized in the on-chip detection of biochemical analytes.

Wide range refractive index sensor using a birefringent optical fiber

In this article, an efficient high birefringent D-shaped photonic crystal fiber (HB-D-PCF) plasmonic refractive index sensor is reported. It is able to work over a long low refractive index analyte range from 1.29 to 1.36. This modified simple structured hexagonal PCF has high birefringence in the near-infrared region. A thin gold film protected by a titanium dioxide (TiO2) layer is deposited on the D-surface of the PCF which acts as surface plasmon active layer. The sensor consists of an analyte channel on the top of the fiber. The performance of the HB-D-PCF is analyzed based on finite element method. Both wavelength and amplitude interrogation techniques are applied to study the sensing performance of the optimized sensor. Numerical results show wavelength and amplitude sensitivity of 9245 nm/RIU and 1312 RIU−1 respectively with high resolution. Owing to the high sensitivity, long range sensing ability as well as spectral stability the designed HB-D-PCF SPR sensor is a potential candidate for water pollution control, glucose concentration testing, biochemical analyte detection as well as portable device fabrication.

A D-Shaped Photonic Crystal Fiber Refractive Index Sensor Coated with Graphene and Zinc Oxide.

A surface plasmon resonance (SPR) sensor based on a D-shaped photonic crystal fiber (PCF) with an uncomplicated structure is proposed to detect the change of refractive index of liquid analytes, and numerical simulation is carried out by the finite element method (FEM). Using silver as the plasmonic metal, the performances of the SPR-PCF sensor coated with a graphene layer and zinc oxide (ZnO) layer were assessed. The sensor designed is only coated with material on the polished surface, which makes the sensor production uncomplicated and solves the problems of filling material in the hole and coating on the hole wall. The effects of structural parameters such as graphene layer thickness, silver layer thickness, ZnO thickness, lattice spacing and manufacturing tolerance of blowhole diameter on the sensor performance were numerically simulated. The numerical results show that the sensitivity of the SPR-PCF sensor coated with 25 nm ZnO is highest in the ZnO thickness range from 10 to 25 nm. In the refractive index range of 1.37–1.41 for liquid analyte, the maximum sensitivity and corresponding resolution reach 6000 nm/RIU and 1.667 × 10−5, respectively. In addition, the sensor has good stability and high structural tolerance under the tolerance of ±5% of blowhole diameter. This work has wide application value in the detection of biochemical analytes, water pollution monitoring, food quality, and medical diagnosis.

A novel hollow core photonic sensor for liquid analyte detection in the terahertz spectrum: design and analysis

A novel hollow core photonic crystal fiber (PCF) is proposed for biochemical analyte detection in the terahertz regime. The prime objective of the work is to increase the sensitivity but other significant features like effective material loss, confinement loss, effective area, numerical aperture and dispersion have been thoroughly investigated over a wide bandwidth using COMSOL version 5.3. Numerical simulation shows that a maximum chemical sensitivity of 99.76% 99.44% and 99.39% can be obtained for benzene, water and methanol respectively at optimum operating conditions. The symmetry in design makes the proposed structure easily feasible to be fabricated using the existing fabrication technologies. Thus it is believed that the proposed PCF has the potential due to its higher sensitivity and lower effective material loss to uplift the standard of PCF sensors and open a new window in this field of research.

CANARY Technology: Working Principles of Biosensor, Detection of Infectious Pathogens

Reusable biosensors for the detection of biochemical analytes are widely used in clinical and laboratory practice. However, biosensors for the detection of pathogenic microorganisms are still under development or implementation. One of these devices is CANARY biosensor (Cellular Analysis and Notification of Antigen Risks and Yields), used by the US Army to indicate pathogenic biological agents. The aim of this article is to consider operating principles and molecular-biological foundations of CANARY biosensor, to analyze the possible directions of work and the prospects for creating domestically made biosensors based on eukaryotic cells. The concept of CANARY is that its receptor component is a B-lymphocyte, modified using genetic engineering, which carries specific IgM-like B-cell receptors on the surface of the cytoplasmic membrane. These cells are able to specifically recognize the target antigen and generate a photosignal through the aequorin protein. Currently, biosensors are already created for the detection of causative agents of plague (100–1000 CFU / ml), tularemia (100 CFU / ml), anthrax (100–500 spores / ml), smallpox (<500 CFU / ml), some toxins (ricin – 3 ng / ml, botulinum toxin – 16 pg / ml). They are based on the CANARY biosensor. Due to high sensitivity and specificity of this method, the relative simplicity and high speed of analysis of one sample, the possibility of analyzing aerosol samples, this technology should be considered as a promising basis for the creation of domestically made biological sensors to detect hazardous biological agents in biological samples, water, food, ecological samples and in aerosols. The deterioration of the global epidemic situation caused by the spread of various strains of SARS-CoV-2 makes sensors based on CANARY technology especially relevant. To create a domestic analogue of such a biosensor, close cooperation with scientific institutions that specialize in molecular genetics and manufacturers of laboratory equipment is required.

Surface plasmon resonance-induced high sensitivity refractive index sensor with adjustable measurement range based on an evanescent field-enhanced D-shaped five-hole photonic crystal fiber

A simple configuration of a D-shaped five-hole photonic crystal fiber (DFPCF)-based surface plasmon resonance (SPR) refractive index (RI) sensor is proposed. A full vector finite element method is applied to simulate the resonant coupling characteristics of the core modes and the surface plasmon polariton (SPP) modes. In addition to its simple structure, a very small polishing depth can introduce a sufficiently strong evanescent field to excite surface plasmon waves, thus ensuring the mechanical strength of the polished fiber. These two key factors lay the foundation for mass production of the sensors. Further, two air holes above the core induce a tunable evanescent field from the core leakage to the polished surface that adjusts the resonance between core modes and SPP modes. A thin layer of gold film is applied to the polished surface to provide a detection platform for liquid analytes without filling pores, forming the SPR effect. Numerical simulation results show that the proposed DFPCF-based SPR RI sensor exhibits sensing performance that is tunable with the film thickness. A maximum wavelength sensitivity of 20 786 nm RIU−1 and widest detection range of 1.30–1.50 are achieved. Due to its improved sensing performance, the liquid RI sensor could be a potential candidate for use in biochemical analyte detection, industrial production, and food and environmental quality monitoring.

Refractive index sensing characteristics in a D-shaped photonic quasi-crystal fiber sensor based on surface plasmon resonance.

A D-shaped photonic quasi-crystal fiber (PQF) sensor based on surface plasmon resonance is proposed for refractive index (RI) sensing. The influences of the width of the gold film, the diameter of the air holes, and the thickness of the gold film on the sensing performance are analyzed. When the RI of a liquid analyte gradually increases from 1.415 to 1.427, the average sensitivity is calculated as 10,250 nm/RIU, and the maximum sensitivity is up to 34,000 nm/RIU, which realizes the high-sensitivity sensing in the near-infrared band. The D-shaped PQF sensor proposed has great application potential in the detection of biochemical analytes and provides a new way to improve the sensing performance.

Rapid analyte concentration estimation from slowly equilibrating sensors

A model is presented that predicts analyte concentration rapidly from slowly equilibrating sensor technology. Specifically, the model characterizes response from a thin coating film deposited on a quartz crystal microbalance (QCM) device and applies directly to ion exchange and adsorption phenomena, but can be modified to any slowly equilibrating system. Several cases are evaluated with emphasis on chemical and biochemical analyte detection. Results demonstrate that the model can predict analyte concentrations after step changes within a few percent of the equilibration time.