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EDC-Mediated Oligonucleotide Immobilization on a Long Period Grating Optical Biosensor
摘要： We present the development and simplification of label-free fiber optic biosensors based on immobilization of oligonucleotides on dual-peak long period gratings (dLPGs). This improvement is the result of a simplification of biofunctionalization methodology. A one-step 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC)-mediated reaction has been developed for the straightforward immobilization of unmodified oligonucleotides on the glass fiber surface along the grating region, leading to covalent attachment of a 5′-phosphorylated probe oligonucleotide to the amino-derivatized fiber grating surface. Immobilization is achieved via a 5′phosphate-specific linkage, leaving the remainder of the oligonucleotide accessible for binding reactions. The dLPG has been tested in different external media to demonstrate its inherent ultrahigh sensitivity to the surrounding-medium refractive index (RI) achieving 50-fold improvement in RI sensitivity over the previously-published LPG sensor in media with RI’s relevant to biological assays. After functionalization, the dLPG biosensor was used to monitor the hybridization of complementary oligonucleotides showing a detectable oligonucleotide concentration of 4 nM. The proposed one-step EDC reaction approach can be further extended to develop fiber optic biosensors for disease analysis and medical diagnosis with the advances of label-free, real-time, multiplex, high sensitivity and specificity.
关键词： EDC-mediated reaction,Label-free,DNA,Oligonucleotide,Optical fiber biosensor,Long period grating
更新于2025-09-23 15:21:01
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Development and Validation of a Surface Plasmon Resonance Biosensor for Specific Detection of Porcine Serum Albumin in Food
摘要： Food allergies are a potential food safety and public health concern worldwide. To assure the safety of people who experience allergic reactions, it is necessary to establish effective and reliable methods for rapid detection of food allergens. This paper reports an innovative method for the rapid detection and analysis of porcine serum albumin (PSA), known as a major allergen in pork, based on a surface plasmon resonance (SPR) biosensor. The antibodies known to have a high bioactivity against PSA were verified by competitive indirect-ELISA and then immobilized on the SPR sensor surface, thus allowing them to capture PSA. The developed SPR demonstrated a linear range from 1.0 to 450 ng/mL for the measurement of PSA with a detection limit of 19.81 ng/mL. Within-day RSD (1.97–4.02%) and between-day RSD (1.88–4.15%) were no more than 5%. The SPR was evaluated for analysis of six commercial food samples and showed almost perfect agreement between the results obtained by ELISA test kits without significant differences (P > 0.05). Therefore, this assay permits accurate, specific, and sensitive detection of PSA in pork and pork products.
关键词： food safety,detection,SPR biosensor,food allergies,porcine serum albumin
更新于2025-09-23 15:21:01
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[IEEE 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz2018) - Nagoya, Japan (2018.9.9-2018.9.14)] 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Detection of Human Tumor Markers with THz Metamaterials
摘要： THz bioanalytical techniques are already proven as a viable tool for the label-free detection of biomolecules. But still, significant improvement of THz sensing techniques is needed to reach application relevant sensitivity levels. We present the label-free THz sensing of human tumor markers using a highly sensitive metamaterial based THz biosensor. High affinity binding of the specific protein to DNA is utilized for localized functionalization to further enhance the detection sensitivity.
关键词： tumor markers,DNA-protein interaction,THz sensing,metamaterials,biosensor
更新于2025-09-23 15:21:01
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Development of an Aptamer Based Luminescent Optical Fiber Sensor for the Continuous Monitoring of Hg2+ in Aqueous Media
摘要： A ?uorescent optical ?ber sensor for the detection of mercury (Hg2+) ions in aqueous solutions is presented in this work. The sensor was based on a ?uorophore-labeled thymine (T)-rich oligodeoxyribonucleotide (ON) sequence that was directly immobilized onto the tip of a tapered optical ?ber. In the presence of mercury ions, the formation of T–Hg2+-T mismatches quenches the ?uorescence emission by the labeled ?uorophore, which enables the measurement of Hg2+ ions in aqueous solutions. Thus, in contrast to commonly designed sensors, neither a ?uorescence quencher nor a complementary ON sequence is required. The sensor presented a response time of 24.8 seconds toward 5 × 10?12 M Hg2+. It also showed both good reversibility (higher than the 95.8%) and selectivity: the I0/I variation was 10 times higher for Hg2+ ions than for Mn2+, and Cu2+, Fe3+, Cd2+ contaminants examined (Co2+, Mn2+, Zn2+, Ca2+, Pb2+, Ni2+, Ag+, and Cu2+) presented an even lower interference. The limit of detection of the sensor was 4.73 × 10?13 M Hg2+ in ultrapure water, and was also able to detect 5 × 10?12 M Hg2+ in buffer solution and 9.03 × 10?13 M Hg2+ in tap water.
关键词： luminescent biosensor,?uorophore-labelled aptamer,optical ?ber biosensor,mercury detection
更新于2025-09-23 15:19:57
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Decoration of porous silicon with gold nanoparticles via layer-by-layer nano-assembly for interferometric and hybrid photonic/plasmonic (bio)sensing
摘要： Gold nanoparticle layers (AuNPLs) enable the coupling of morphological, optical, and electrical properties of gold nanoparticles (AuNPs) with tailored and specific surface topography, making them exploitable in many bio-applications (e.g. biosensing, drug delivery, photothermal therapy). Herein, we report the formation of AuNPLs on porous silicon (PSi) interferometers and distributed Bragg reflectors (DBRs) for (bio)sensing applications via layer-by-layer (LbL) nano-assembling of a positively charged polyelectrolyte, namely polyallylamine hydrochloride (PAH), and negatively charged citrate-capped AuNPs. Decoration of PSi interferometers with AuNPLs enhances the Fabry-Perot fringe contrast due to increased surface reflectivity, resulting in an augmented sensitivity for both bulk and surface refractive index sensing, using NaCl aqueous solutions to infiltrate the pores (roughly 4.5-fold), in the former, and unspecific bovine serum albumin (BSA) adsorption on the pore surface (roughly 2.6-fold), in the latter. Sensitivity enhancing is also confirmed for affinity and selective biosensing of streptavidin (roughly 2.5-fold) using a biotinylated polymer, namely, negatively-charged poly(methacrylic acid) (b-PMAA). Further, decoration of PSi DBR with AuNPLs envisages building up a hybrid photonic/plasmonic optical sensing platform. Indeed, both photonic (DBR stop-band) and plasmonic (localized surface plasmon resonance, LSPR) peaks of the hybrid structure are sensitive to changes of bulk refractive index (using 35% glucose aqueous solutions) and BSA unspecific adsorption. To the best of our knowledge, this is the first report about the formation of AuNPLs via LbL nano-assembly on PSi for i) the enhancing of the interferometric performance in (bio)sensing applications and ii) the building up of hybrid photonic/plasmonic platforms for sensing and perspective biosensing applications.
关键词： Layer-by-Layer (LbL) nano-assembly,Porous Silicon (PSi),Biosensor,Interferometer,Gold nanoparticles (AuNPs),Hybrid Photonic/Plasmonic,Distribute Bragg Reflector (DBR),Sensor
更新于2025-09-23 15:19:57
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A versatile fluorometric in-situ hybridization method for the quantitation of hairpin conformations in DNA self-assembled monolayers
摘要： As the performance of hairpin DNA (hpDNA)-based biosensors is highly dependent on the yield of stem-loop (hairpin) conformations, we report herein a versatile fluorometric in-situ hybridization protocol for examining hpDNA self-assembled monolayers (SAMs) on popularly used biochip substrates. Specifically, the ratio of fluorescence (FL) intensities of hpDNA SAMs (in an array format) before and after hybridization was adapted as the key parameter for performing such a determination. Upon confirming the existence of mixed and tunable DNA conformations in binary deposition solutions and the efficient hybridization of the hairpin strands with target DNA via gel electrophoresis assays, we have tested the fluorometric protocol for determining the coverages of hpDNA in hpDNA/ssDNA SAMs prepared on gold; its accuracy was validated by Exonuclease I (Exo I)-assisted electrochemical quantitation. To further confirm its versatility, this FL protocol was adapted for quantifying hairpin conformations formed on glass and polycarbonate (PC) substrates. The molar ratios of surface-tethered hairpin conformations on the three different substrates were all found to be proportional to but less than that in the binary deposition solutions, and dependent on the substrate morphology. The findings reported herein are beneficial to the construction of highly efficient DNA hairpin-based sensing surfaces, which essentially facilitates the creation of hpDNA-based biosensors with optimal detection performance.
关键词： In-situ hybridization,conformation evaluation,DNA biosensor/biochip,fluorescence microarray,Hairpin DNA
更新于2025-09-23 15:19:57
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A chemically modified laser-induced porous graphene based flexible and ultrasensitive electrochemical biosensor for sweat glucose detection
摘要： Porous laser-induced graphene (LIG) is an attractive and promising carbon material for electrochemical applications because it can immobilize various proteins, such as enzymes, antibodies, and receptors. However, poor inherent electrical properties caused by low surface conductivity is still a critical drawback for various applications. Here, we have proposed a surface modification method for the LIG electrode using acetic acid treatment via facile and practicable dipping technique. This simple acetic acid treatment dramatically increased the ratio of carbon-carbon bonds which effectively increased conductivity and decreased sheet resistance. Importantly, these unique properties also facilitated the stable and uniform dispersion of highly catalytic Pt nanoparticles (PtNPs) on LIG by avoiding the concentration of electric field on nanoparticles that can cause aggregation during electrodeposition. Finally, chitosan-glucose oxidase (GOx) composite was successfully immobilized onto the LIG/PtNPs electrode to fabricate a sweat glucose biosensor. The as-prepared LIG/PtNPs electrode exhibited a high sensitivity of 4.622 μA/mM as well as an ultra-low limit of detection (signal to noise ratio is 3) which was less than 300 nM and dynamic linear range up to 2.1 mM. Furthermore, we tested the variation of blood glucose level before and after meal using the amperometric response of the sensor which demonstrates the commercial potential of this unique sweat glucose biosensor.
关键词： Sweat glucose detection,Laser-induced graphene (LIG),Acetic acid treatment,Ultra-sensitive and -low detection limit,Electrochemical biosensor
更新于2025-09-23 15:19:57
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Dual-Wavelength Electrochemiluminescence Ratiometric Biosensor for NF-?oB p50 Detection with Dimethylthiodiaminoterephthalate Fluorophore and Self-Assembled DNA Tetrahedron Nanostructures Probe
摘要： Here, we have fabricated a dual-wavelength electrochemiluminescence ratiometric biosensor based on electrochemiluminescent resonance energy transfer (ECL-RET). In this biosensor, Au nanoparticle-loaded graphitic phase carbon nitride (Au-g-C3N4) as donor, and Au-modified dimethylthiodiaminoterephthalate (TAT) analogue (Au@TAT) as acceptor are investigated for the first time. Besides, tetrahedron DNA probe is immobilized onto Au-g-C3N4 to improve the binding efficiency of transcription factor and ECL ratiometric changes on the basis of the ratio of ECL intensity of 595 nm and 460 nm are obtained through the formation of sandwich structure of DNA probe-antigen-antibody. Our biosensor achieves the assay of NF-κB p50 with a detection limit of 5.8 pM as well as high stability and specificity.
关键词： NF-κB p50,Dimethylthiodiaminoterephthalate (TAT),DNA tetrahedron nanostructures,electrochemiluminescence,ratiometric biosensor
更新于2025-09-23 15:19:57
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Stretchable and Skin-Conformable Conductors Based on Polyurethane/Laser-Induced Graphene
摘要： The conversion of various polymer substrates into laser-induced graphene (LIG) with a CO2 laser in ambient condition is recently emerging as a simple method for obtaining patterned porous graphene conductors, with a myriad of applications in sensing, actuation, and energy. In this paper, a method is presented for embedding porous LIG (LIG-P) or LIG fibers (LIG-F) into a thin (about 50 μm) and soft medical grade polyurethane (MPU) providing excellent conformal adhesion on skin, stretchability, and maximum breathability to boost the development of various unperceivable monitoring systems on skin. The effect of varying laser fluence and geometry of the laser scribing on the LIG micro?nanostructure morphology and on the electrical and electromechanical properties of LIG/MPU composites is investigated. A peculiar and distinct behavior is observed for either LIG-P or LIG-F. Excellent stretchability without permanent impairment of conductive properties is revealed up to 100% strain and retained after hundreds of cycles of stretching tests. A distinct piezoresistive behavior, with an average gauge factor of 40, opens the way to various potential strain/pressure sensing applications. A novel method based on laser scribing is then introduced for providing vertical interconnect access (VIA) into LIG/MPU conformable epidermal sensors. Such VIA enables stable connections to an external measurement device, as this represents a typical weakness of many epidermal devices so far. Three examples of minimally invasive LIG/MPU epidermal sensing proof of concepts are presented: as electrodes for electromyographic recording on limb and as piezoresistive sensors for touch and respiration detection on skin. Long-term wearability and functioning up to several days and under repeated stretching tests is demonstrated.
关键词： biosensor,epidermal,porous graphene,stretchable conductor,laser
更新于2025-09-23 15:19:57
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A Microfluidic Biosensor Based on Magnetic Nanoparticle Separation, Quantum Dots Labeling and MnO2 Nanoflower Amplification for Rapid and Sensitive Detection of Salmonella Typhimurium
摘要： Screening of foodborne pathogens is an effective way to prevent microbial food poisoning. A microfluidic biosensor was developed for rapid and sensitive detection of Salmonella Typhimurium using quantum dots (QDs) as fluorescent probes for sensor readout and manganese dioxide nanoflowers (MnO2 NFs) and as QDs nanocarriers for signal amplification. Prior to testing, amino‐modified MnO2 nanoflowers (MnO2‐NH2 NFs) were conjugated with carboxyl‐modified QDs through EDC/NHSS method to form MnO2‐QD NFs, and MnO2‐QD NFs were functionalized with polyclonal antibodies (pAbs) to form MnO2‐QD‐pAb NFs. First, the mixture of target Salmonella Typhimurium cells and magnetic nanoparticles (MNPs) modified with monoclonal antibodies (mAbs) was injected with MnO2‐QD‐pAb NFs into a microfluidic chip to form MNP‐bacteria‐QD‐MnO2 complexes. Then, glutathione (GSH) was injected to dissolve MnO2 on the complexes into Mn2+, resulting in the release of QDs. Finally, fluorescent intensity of the released QDs was measured using the fluorescent detector to determine the amount of Salmonella. A linear relationship between fluorescent intensity and bacterial concentration from 1.0 × 102 to 1.0 × 107 CFU/mL was found with a low detection limit of 43 CFU/mL and mean recovery of 99.7% for Salmonella in spiked chicken meats, indicating the feasibility of this biosensor for practical applications.
关键词： quantum dots,manganese dioxide nanoflowers,Salmonella Typhimurium,Microfluidic biosensor,magnetic nanoparticles
更新于2025-09-23 15:19:57