Field Of Biological Detection Research Articles

Widening of Dynamic Detection Range in Real-Time Angular-Interrogation Surface Plasmon Resonance Biosensor Based on Anisotropic Van Der Waals Heterojunction.

Surface plasmon resonance (SPR) biosensors have experienced rapid development in recent years and have been widely applied in various fields. Angular-interrogation SPR biosensors play an important role in the field of biological detection due to their advantages of reliable results and high stability. However, angular-interrogation SPR biosensors also suffer from low detection sensitivity, poor real-time performance, and limited dynamic detection range, which seriously restricts their application and promotion. Therefore, we designed an angular-interrogation SPR biosensor based on black phosphorus (BP)/graphene two-dimensional (2D) van der Waals heterojunction (vdWhs). On the basis of using the angle-fixed method, this biosensor not only has good real-time performance but also detection sensitivity enhancement. The optical anisotropy characteristic of BP is used to widen the dynamic detection range of biosensors. The simulation results show that the maximum detection sensitivity of the proposed biosensor is 258.6 deg/RIU. Compared with the bare-Ag film structure biosensor, the detection sensitivity was enhanced by 209.2% by 2D vdWhs. The use of anisotropic 2D material BP can not only enhance the detection sensitivity but also widen the detection range. When the fixed incident angle is θ = 5 deg, a maximum dynamic detection range enhanced factor of 123.1% can be achieved, and a detection sensitivity of 185.2 deg/RIU in the corresponding interval can be obtained. The proposed biosensor in this study has potential broad application prospects in several fields, such as biological detection.

Recent Progress in Organic Electrochemical Transistor-Structured Biosensors.

The continued advancement of organic electronic technology will establish organic electrochemical transistors as pivotal instruments in the field of biological detection. Here, we present a comprehensive review of the state-of-the-art technology and advancements in the use of organic electrochemical transistors as biosensors. This review provides an in-depth analysis of the diverse modification materials, methods, and mechanisms utilized in organic electrochemical transistor-structured biosensors (OETBs) for the selective detection of a wide range of target analyte encompassing electroactive species, electro-inactive species, and cancer cells. Recent advances in OETBs for use in sensing systems and wearable and implantable applications are also briefly introduced. Finally, challenges and opportunities in the field are discussed.

A multilevel core-shell structure Fe3O4@SiO2@InGaO@SiO2 magnetic particles for DNA extraction

DNA extraction is greatly significant in biological detection fields, including species identification, pathogen detection, environmental monitoring, biosafety, and food safety. Scientific research and practical application must conduct high-quality trace DNA separation, purification and extraction. Herein, a two-step strategy successfully prepares a multilevel core–shell structure Fe3O4@SiO2@InGaO@SiO2 magnetic particles for trace DNA extraction. The morphologies, structures, elemental compositions, components, and properties of the materials are systematically characterized. Fe3O4@SiO2@InGaO@SiO2 magnetic particles in the chaotropic salt solutions are used to directly target DNA binding due to the existence of Si-O–H bond. The maximum DNA adsorption rate can highly reach 83.1 % after 700 °C annealing in the air for 30 min, far exceeding the adsorption rate of commercial reagent kit, which is attributed to the increased specific surface area. The excellent result is conducive to rapid DNA extraction in practical applications, especially in daily criminal cases, further promoting social security and stability.

MnO2-based dual channel surface plasmon resonance fiber sensor for trace glutathione and refractive index detection.

Glutathione (GSH) plays vital role in human biological systems, so its rapid and sensitive detection is necessary for health condition monitoring. In this work, a simple structure for dual channel GSH and refractive index (RI) detection is proposed. By introducing Au-MnO2 thin film coating on the fiber surface for the first time, GSH solution would lead to the dissolution of MnO2, the change in GSH levels could be monitored over a short period in channel 2. For channel 1, ITO-Ag thin film is applied for RI change detection. After optimization, the GSH detection sensitivity reached about -2.361 nm/mM in the range of 0.005-50 mM, and the RI sensitivity reached 1704.252 nm/RIU in the range of 1.331-1.3895 RIU. Channel 1 could also put into GSH detection in the high concentration scale to enlarge the sensor's range and 0.095 nm/mM of sensitivity is acquired within the range of 50-600 mM. With the presence of MnO2 film, the detection sensitivity increased 25.663 times. Neither channel interferes with the operation of the other. Proposed sensor provides stability, high selectivity and elevation in GSH detection sensitivity, which shows great potential for environmental and biological detection field and their applications.

Dual-current signal high-sensitivity detection of telomerase using signal amplified DNA functionalized metal-organic frameworks in glass nanopipettes

As a biomarker for early cancer diagnosis, the quantitative and sensitive detection of telomerase is very hot topic in the field of biological detection. In this work, we reported a novel telomerase assay strategy-based glass nanopipettes (GNs) which were constructed with DNA functionalized metal-organic frameworks (MOFs, PCN-224, C144H112N12O64Zr15) as composite probes (DNA-PCN-224, DNA-PCN-224-MB (methylene blue)). The composite probes provided more probe binding sites, so the aggregation behavior of the composite probes would occur obviously in nanopores restricted domain space under the recognition and amplification of telomerase. The relative size of the GNs reduced due to the size effect of MOFs. This size effect exhibits a good signal-to-noise ratio in large pores, resulting in signal amplification. With different modifications of the GNs, on the one hand, the reduction of the relative pore size amplified the ionic current signal; on the other hand, the electrolytic current signal further verified the reliability of this signal amplification, which originated from the transfer of electrons occurring on the gold layer by the electroactive substance MB. The former quantified the assay, allowing a telomerase detection range of 0–10,000 Hela cells/mL and a detection limit of 100 Hela cells/mL. This work provided a detection platform for detecting related telomerase diseases and opened a new detection method of double signals.

Molecular machine powered catalytic hairpin assembly for signal-on electrochemical detection of Alzheimer’s amyloid-β oligomer

We have developed a bipedal driven catalytic hairpin assembly for the electrochemical detection of highly sensitive amyloid-β oligomers. Aptamers specifically recognize of amyloid-βoligomers can activate catalytic hairpin assembly and form bipedal molecular machines. Catalytic hairpin assembly hybridizes with surface-fixed hairpin DNA1 (HP1) through proximity effect, exposing the pre-locking foot domain of HP1 for fusion with ferrocene labeled hairpin DNA2 (HP2-Fc). The electrochemical signal molecule Fc approaches the electrode under the action of fulcrum mediated chain shift reaction, and the bipedal molecular machines generated by catalytic hairpin assembly crosses the surface of the sensor, where a large number of ferrocenes HP1-HP2 bipedal structures towards the electrode are formed, which realizes the amplification of the electrochemical signal. The linear detection range of this component is 0.1 pM∼1 nM, and the detection limit is 38 fM. As an enzyme-free detection method, it can realize the high sensitivity and specificity detection of multiple target proteins through the appropriate DNA-based affinity probe, which has great reference significance and application value in the field of biological detection.

High resolution UV spectral imaging and bio-detection with magnetic dipole quasi-BIC resonant dielectric metasurfaces

In this paper, we designed a ring-shaped metasurface based on diamond material that response in ultraviolet band, and with which the BIC mode is obtained by breaking the symmetry of its structural units. We show that only when the radiation rate of the magnetic dipole resonance of the BIC mode is equal to the dissipation loss brought by the surface covering material, the interaction between light and matter is maximally enhanced. The absorptivity of the film material is enhanced by an order of magnitude. The simulation results show that there is a linear relationship between the resonant positions of the structure and the scaling factor S varying structure sizes. When the metasurface is covered with a single DNA film, changes differently due to the absorption of the DNA. The reflection information of the system is further converted into ultraviolet absorption of DNA. Then the multiple absorption peaks form the absorption spectrum of DNA molecules. By Arranging the different scaling factor metasurface pixels on a same substrate we can obtain a specific absorption image. The absorptivity of DNA leads to the difference in brightness and darkness of the metasurface pixels, which can be processed into gray-scale images that give out the specific fingerprint information of the DNA. So, we realized calibration and analysis of DNA without spectroscopic measurements in the ultraviolet band now. The metasurface device can effectively detect the contamination of DNA by other biomolecules such as RNA. This work has great significance in promoting the application of metasurfaces in the field of biological detection and demonstrates that a specially designed metasurface can be applied in nucleic acid detection.

Two Types of Subgroup-Valence Heteroatoms (PIII, TeIV) Synergistically Controlling Octa-CeIII-Encapsulated Heteropolyoxotungstate and Its Electrochemical Recognition Properties.

Rapid development of the synthetic chemistry of polyoxometalates (POMs) has greatly driven the generation of structurally variable innovative POM-based materials. Herein, we synthesized a novel PIII and TeIV synergistically controlling octa-CeIII-encapsulated heteropolyoxotungstate [H2N(CH3)2]11K2Na6H11[Ce8(CH3COO)2(HPIIIO3)2W8O20(H2O)12(B-β-TeW8O30)2(B-α-TeW8O31)4]·64H2O (1). Its distinctive anion skeleton [Ce8(CH3COO)2(HPIIIO3)2W8O20(H2O)12(B-β-TeW8O30)2(B-α-TeW8O31)4]30- is built by two tetra-vacancy [B-β-TeW8O30]8- and four tetra-vacancy [B-α-TeW8O31]10- moieties linked through an inorganic-organic hybrid [Ce8(CH3COO)2(HPIIIO3)2W8O20(H2O)12]26+ {Ce8P2W8} cluster core. Interestingly, {Ce8P2W8} is assembled from four [W2O11]10- groups and two [HPIIIO3]2- anions and eight Ce3+ ions. Besides, 1 was further composited with carboxylated multiwalled carbon nanotube (CMCN), resulting in a bi-component 1/CMCN nanocomposite. An electrochemical recognition platform (named as 1/CMCN/GCE) was built by modifying 1/CMCN on a glassy carbon electrode (GCE) for electrochemical detection of dopamine (DPA) at physiological pH (pH = 7.0). The findings have shown that 1/CMCN/GCE exhibits a good detection limit of 4.95 nM for DPA. This work provides considerable inspiration to promote innovative and rational structure designs of POM-based materials and expand their applications to electrochemical and biological detection fields.

Luminol functionalized tin dioxide nanoparticles with catalytic effect for sensitive detection of glucose and uric acid

In this work, novel luminol functionalized nanoparticles (SnO2@Luminol NPs) with mesoporous spherical structure were synthesized by a simple and green method, which exhibited good chemiluminescence (CL) intensity without any additional catalysts. In addition, the CL intensities generated by SnO2@Luminol/H2O2 system were linearly related to the logarithm values of H2O2 concentrations, and CL mechanism of SnO2@Luminol/H2O2 system was investigated. On this basis, a sensitive CL method was proposed to determine glucose and uric acid. The fabricated CL method displayed wide linear ranges (glucose, 1.0 × 10−8 – 1.0 × 10−4 M; uric acid, 1.0 × 10−8 – 1.0 × 10−4 M) and low detection limits (glucose, 5.4 nM; uric acid, 6.8 nM). The proposed CL method achieved sensitive and specific glucose and uric acid detection in human serum specimens, and the measured results were consistent with the clinical diagnosis. Furthermore, as long as the product of reaction between enzyme and substrate is H2O2, this CL method can also be extended to other biological detection fields.

Active Aberration Correction with Adaptive Coefficient SPGD Algorithm for Laser Scanning Confocal Microscope.

A laser scanning confocal microscope (LSCM) is an effective scientific instrument for studying sub-micron structures, and it has been widely used in the field of biological detection. However, the illumination depth of LSCMs is limited due to the optical aberrations introduced by living biological tissue, which acts as an optical medium with a non-uniform refractive index, resulting in a significant dispersion of the focus of LSCM illumination light and, hence, a loss in the resolution of the image. In this study, to minimize the effect of optical aberrations, an image-based adaptive optics technology using an optimized stochastic parallel gradient descent (SPGD) algorithm with an adaptive coefficient is applied to the optical path of an LSCM system. The effectiveness of the proposed aberration correction approach is experimentally evaluated in the LSCM system. The results illustrate that the proposed adaptive optics system with an adaptive coefficient SPGD algorithm can effectively reduce the interference caused by aberrations during depth imaging.

Development of a fluorescein modified ruthenium(II) complex probe for lysosome-targeted ratiometric luminescence detection and imaging of peroxynitrite in living cells

Ratiometric luminescence (fluorescence/phosphorescence) probes have attracted widespread attention of researchers in the field of biological detection and noninvasive imaging of bioactive molecules in living systems. However, most of them suffer from some defects such as small emission shift, different excitation wavelength and spectral overlap, which eventually affect the luminescence ratio, thus leading to limitations in ratiometric bioimaging applications. In this paper, we present a novel “ruthenium(II) complex-fluorescein” scaffold probe (Ru-FL-ONOO) for ratiometric luminescence detection of peroxynitrite (ONOO−), in which a Ru(II) complex was conjugated to fluorescein serving as the dual-emissive moiety and the spirocyclic structure of fluorescein-phenylhydrazine was used as the specifically-reactive moiety for recognizing ONOO−. The probe possesses not only favourable specificity but also high sensitivity for responding to ONOO−, exhibiting a large emission shift (Δλem > 120 nm) at a single excitation wavelength. After being transferred into living cells, the probe localized within lysosomes, allowing ONOO− therein to be imaged at ratiometric mode. The imaging results reveal that the ratiometric probe bearing the Ru(II) complex-fluorescein scaffold could be a useful approach for overcoming the drawback of spectral overlap of dual-emissive moiety under single-wavelength excitation so as to improve the signal-to-noise ratio, thus benefiting the development of ratiometric bioimaging.

High Sensitivity Temperature and Curvature Sensor Based on Mach-Zehnder Interferometer With Tapered Two Peanut-Shaped Structures

A high-sensitivity temperature and curvature microfiber Mach-Zehnder interferometer (MMZI) with two peanut-shaped structures is proposed and demonstrated for the first time. The interferometer consists of a section of microfiber and two peanut-shaped structures. The microfiber can be easily affected by the external environment due to its strong evanescent field on the surface and the peanut-shaped structure is conducive to excite fundamental mode to high-order mode, which is beneficial to realize high-sensitivity sensing detection. The experimental results show that the maximum temperature sensitivity of &#x2212;678.67 pm<inline-formula> <tex-math notation="LaTeX">$/$ </tex-math></inline-formula>&#x00B0;C is obtained in the range of 30 &#x00B0;C to 42 &#x00B0;C, which is the highest temperature sensitivity we have known in the peanut-shaped structure sensor. Furthermore, the sensor is also used for curvature measurements. The curvature sensitivity can be up to &#x2212;79.09 nm<inline-formula> <tex-math notation="LaTeX">$/\text{m}$ </tex-math></inline-formula>^&#x2212;1 from 0.10188 m^&#x2212;1 to 0.20374 m^&#x2212;1. Therefore, the proposed sensor will have good application prospects in the field of biological detection and environment monitoring due to the advantage of high temperature sensitivity.

A Ti3C2-MXene-functionalized LRSPR biosensor based on sandwich amplification for human IgG detection.

Long-range surface plasmon resonance (LRSPR) has demonstrated excellent performance in sensing and detection, due to its higher accuracy and sensitivity compared with conventional surface plasmon resonance (cSPR). In this work, we establish an LRSPR biosensor which employs PDA/Ti3C2-MXene/PDA-gold film as a sensing substrate and gold nanoparticles (AuNPs) as enhancers. Ti3C2-MXene is an emerging two-dimensional (2D) layered material which is used extensively in immunoassay and biosensing. The sensing substrate comprises two polydopamine (PDA) films between which is sandwiched a Ti3C2-MXene film based on a gold film, which provides a large surface area and abundant binding sites to rabbit anti-human IgG (Ab1). Sandwich amplification is adopted to enhance the sensitivity of the LRSPR biosensor, and AuNPs/staphylococcal protein A (SPA)/mouse anti-human IgG (Ab2) composites are introduced into the flow cell as enhancers after the immune binding of human IgG to Ab1. The antigen (human IgG) detection range is 0.075μgmL-1 to 40μgmL-1, and the limit of detection is almost 20 times lower than that for cSPR biosensors. This novel LRSPR biosensor demonstrates excellent performance in immune sensing over a broad detection range and a low limit of detection. Subsequent modification of the LRSPR sensing platform could be made for extensive application in various biological detection fields.

A High-Sensitivity SPR Refractive Index Sensor Based on No-Core Fiber with Ag-Cu Composite Films.

A fiber/Ag-Cu films surface plasmon resonance (SPR) refractive index (RI) sensor composed of multimode fiber-no-core-fiber-multimode fiber (MMF-NCF-MMF) structure is designed. The sensing region length and Cu film deposition time of sensor are gradually optimized by the control variable method, which finally achieves the improvement of sensor properties. We experimentally compared the sensing performance of the fiber/Ag film and fiber/Ag-Cu films sensor. Experimental results show that the fiber/Ag-Cu films sensor has good linearity (R-square = 0.993), and its sensitivity is as high as 3957 nm/RIU in the refractive index detection range of 1.3328–1.3853, which is 1109 nm/RIU higher than the sensitivity of a conventional fiber/Ag film sensor. The sensor presented in this paper adopts the structure with composite metal film, which outperforms the common single-layer metal film in chemical stability such as oxidation resistance and mechanical hardness. Meanwhile, the SPR sensor with MMF-NCF-MMF structure has the advantages of convenient manufacture and compact structure. In conclusion, it can bestow a unique advantage in the field of biological detection or chemical analysis.

Red blood cell recognition and posture estimation in microfluidic chip based on lensless imaging.

On the one hand, lensless imaging technology has become one of the key technologies to achieve point-of-care testing; on the other hand, microfluidic technology has shown great application potential in the field of biological detection. Using mainstream lensless imaging technology to achieve biological cell imaging in microfluidic chips has technical limitations. In particular, it is more difficult to achieve lensless imaging for non-spherical cells in microfluidic chips such as red blood cells. Achieving red blood cell recognition and posture estimation in a microfluidic chip under the lensless imaging, combined with mainstream lensless imaging technology, can provide more effective red blood cell morphological parameters for medical diagnosis. In this paper, the method for red blood cell recognition and posture estimation in microfluidic chips based on lensless imaging is given. First, the relevant theoretical basis is introduced. Then, the models of red blood cell recognition and posture estimation in microfluidic chips based on lensless imaging are given. The effect of red blood cell flipping on lensless imaging is analyzed in the modeling process. Finally, the effectiveness of the proposed method is verified by experiments. Experiments show that the proposed method can well achieve red blood cell recognition and posture estimation through the shape characteristics of red blood cells.

Tunable mid-infrared refractive index sensor with high angular sensitivity and ultra-high figure-of-merit based on Dirac semimetal

A tunable mid-infrared refractive index sensor consisting of bulk-Dirac-semimetal (BDS) and one-dimensional photonic crystals (1DPC) is proposed. This sensor has high angular sensitivity and ultra-high figure-of-merit (FOM), which is attributed to the optical Tamm states excited at the interfaces between BDS and 1DPC. Our numerical simulations show that the maximum value of the angular sensitivity and FOM of the sensor can reach up to 711.8°/RIU and 6001 RIU−1 respectively, which are much higher than those of the reported similar sensors. The simulations also demonstrate that the sensing performance can be adjusted by the Fermi energy and the structural parameters of the sensor. It is believed that, with the simple structure and the excellent performance, the proposed sensor has a broad application prospect in the field of biological detection.

Recent Progress in NIR-II Contrast Agent for Biological Imaging.

Fluorescence imaging technology has gradually become a new and promising tool for in vivo visualization detection. Because it can provide real-time sub-cellular resolution imaging results, it can be widely used in the field of biological detection and medical detection and treatment. However, due to the limited imaging depth (1–2 mm) and self-fluorescence background of tissue emitted in the visible region (400–700 nm), it fails to reveal biological complexity in deep tissues. The traditional near infrared wavelength (NIR-I, 650–950 nm) is considered as the first biological window, because it reduces the NIR absorption and scattering from blood and water in organisms. NIR fluorescence bioimaging's penetration is larger than that of visible light. In fact, NIR-I fluorescence bioimaging is still interfered by tissue autofluorescence (background noise), and the existence of photon scattering, which limits the depth of tissue penetration. Recent experimental and simulation results show that the signal-to-noise ratio (SNR) of bioimaging can be significantly improved at the second region near infrared (NIR-II, 1,000–1,700 nm), also known as the second biological window. NIR-II bioimaging is able to explore deep-tissues information in the range of centimeter, and to obtain micron-level resolution at the millimeter depth, which surpass the performance of NIR-I fluorescence imaging. The key of fluorescence bioimaging is to achieve highly selective imaging thanks to the functional/targeting contrast agent (probe). However, the progress of NIR-II probes is very limited. To date, there are a few reports about NIR-II fluorescence probes, such as carbon nanotubes, Ag2S quantum dots, and organic small molecular dyes. In this paper, we surveyed the development of NIR-II imaging contrast agents and their application in cancer imaging, medical detection, vascular bioimaging, and cancer diagnosis. In addition, the hotspots and challenges of NIR-II bioimaging are discussed. It is expected that our findings will lay a foundation for further theoretical research and practical application of NIR-II bioimaging, as well as the inspiration of new ideas in this field.

Measuring the Refractive Index and Its Two-Dimensional Distribution of Picoliter Microfluidics With the Scanning White Light Interference Microscopy Method

Measurements on refractive index and its distribution of microfluidics are widely applied in the field of biological detection, chemical analysis, material researches, medical diagnostics, and lab on a chip. Since the volume of the microfluidics is ultra-small, such as nanoliters or even picoliters, measuring the refractive index of microfluidics is challenging. We here presents an effective method to measure the refractive index and its two-dimensional distribution of picoliter microfluidics by the SWLI (scanning white light interference) microscopy technology. This method has the advantages of simplicity, low cost, non-contact, wide measurement range and high precision. We conduct the experiment to measure the refractive index of 2.4 picoliters liquid. The resolution is 10−4RIU (refractive index unit), and the relative error is 10−4 compared with the Abbe refractometer. We obtained the relationship between refractive index and concentration of glucose solution. In addition, we can measure the 2D (two-dimensional) distribution of RI (refractive index) of liquids. We can observe the liquid interface between deionized water and liquid paraffin clearly. Besides, we can observe the process of solute dissolution in the liquid and the change of refractive index.

Highly sensitive and tunable terahertz biosensor based on optical Tamm states in graphene-based Bragg reflector

A highly sensitive and tunable biosensor at terahertz (THz) frequencies is proposed by using a composite structure of graphene and one-dimensional photonic crystal. The theoretical analysis and simulation results show that the sensitivity and figure-of-merit of the biosensor can reach 517.9°/RIU and 222.9RIU- 1, respectively. The high sensitivity of the biosensor originates from the excitation of optical Tamm states caused by graphene-based distributed Bragg reflector. By varying the voltage on graphene, we can electrically control the sensitivity and figure-of-merit of the biosensor. Furthermore, we have shown that the biosensor has a wide range (1.40–1.70) for measuring the refractive index of the sensing medium. We believe the biosensor has a good application prospect in the field of biological detection.

Sensitivity enhanced D-type large-core fiber SPR sensor based on Gold nanoparticle/Au film co-modification

A D-type large core optical fiber sensor with high sensitivity and good stability based on the coupling of gold nanoparticles and Au film was proposed and demonstrated by simulation and experiments. The proposed sensor is numerically simulated based on the finite element method. The simulation shows that the electric field intensity of the gap coupling between gold nanoparticles and Au film is 4–5 times higher than that of Au film, and the electric field intensity on the surface of gold nanoparticles is twice as strong as that on the surface of Au films. The electric field coupling effect between the Au film surface plasmon resonance (SPR) and the gold nanoparticle localized surface plasmon resonance (LSPR) can improve the refractive index sensitivity of the sensor. Experimental results show that the refractive index sensitivity of D-type optical fiber/Au film/gold nanoparticles sensor reaches 3074 nm/refraction index unit (RIU), which is 1.4 times that of D-type optical fiber/Au film sensor. SPR–LSPR coupling effect is a good method to improve the sensing performance of optical fiber sensors, especially for detecting the refractive index changes of surrounding media. Compared with existing similar biosensors, the designed biosensor has higher sensitivity and the sensor proposed in this paper has great application prospects in the field of biological detection.