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Rapid and Digital Detection of Inflammatory Biomarkers Enabled by a Novel Portable Nanoplasmonic Imager
摘要： New point-of-care diagnostic devices are urgently needed for rapid and accurate diagnosis, particularly in the management of life-threatening infections and sepsis, where immediate treatment is key. Sepsis is a critical condition caused by systemic response to infection, with chances of survival drastically decreasing every hour. A novel portable biosensor based on nanoparticle-enhanced digital plasmonic imaging is reported for rapid and sensitive detection of two sepsis-related inflammatory biomarkers, procalcitonin (PCT) and C-reactive protein (CRP) directly from blood serum. The device achieves outstanding limit of detection of 21.3 pg mL?1 for PCT and 36 pg mL?1 for CRP, and dynamic range of at least three orders of magnitude. The portable device is deployed at Vall d’Hebron University Hospital in Spain and tested with a wide range of patient samples with sepsis, noninfectious systemic inflammatory response syndrome (SIRS), and healthy subjects. The results are validated against ultimate clinical diagnosis and currently used immunoassays, and show that the device provides accurate and robust performance equivalent to gold-standard laboratory tests. Importantly, the plasmonic imager can enable identification of PCT levels typical of sepsis and SIRS patients in less than 15 min. The compact and low-cost device is a promising solution for assisting rapid and accurate on-site sepsis diagnosis.
关键词： imaging biosensors,nanoplasmonics,point-of-care diagnostics,sepsis,gold nanoparticles
更新于2025-09-12 10:27:22
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Advances in nanoplasmonic biosensors for clinical applications
摘要： Biomarkers are unquestionable biological indicators for diagnosis and therapeutic interventions providing appropriate classification of a wide range of health disorders and risk factors. Nonetheless, the detection and quantification of biomarkers need to be tested with sufficient reliability by robust analytical methods in order to assure clinical performance in health care settings. Since the analytical performance is determined by the sensitivity and specificity of the method employed, techniques have been intensively refined in order to avoid the misinterpretation of results and undesirable bias. Although biomarkers can be detected with the existing analytical techniques, to reproducibly quantify them in decentralized settings or remote locations with the required accuracy is still a challenge. Currently, only a few point-of-care devices for biomarker evaluation are commercially available. Thus, more focused research efforts are needed to overcome these limitations in order to provide universal patient-centered care platforms. To this end, plasmonic biosensors can be conveniently used as portable diagnostic devices for attaining timely and cost-effective clinical outcomes. The development of enhanced performance based on nanoplasmonics technology opens the way for sensor miniaturization, multiplexing and point of care testing. This review covers recent advances and applications of plasmonic and nanoplasmonic biosensors intended for biomarker diagnosis in clinical practice, including cancer, cardiovascular and neurodegenerative diseases. The review specially focuses on: (i) recent progress in plasmonics development including the design of singular nanostructured surfaces, (ii) novel chemical functionalization strategies for the appropriate incorporation of bioreceptors and (iii) plasmonic applications as real operative devices in the clinical field. Future prospects in the use of nanoplasmonic sensor platforms for personalised quantification and management of biomarkers directly in body fluids will also be discussed.
关键词： clinical applications,SPR,point-of-care testing,nanoplasmonic biosensors,biomarkers,LSPR
更新于2025-09-12 10:27:22
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A turn-on graphene quantum dot and graphene oxide based fluorometric aptasensor for the determination of telomerase activity
摘要： A turn-on fluorometric assay is described for determination of the activity of enzyme telomerase. For this purpose, graphene quantum dots (GQDs) were first modified with the telomeric sequence (5′-amino-AATCCGTCGAGCAGAGTT-3′) via a condensation reaction. Injection of graphene oxide causes instant quenching of the blue fluorescence of the GQDs. Addition of cell extract containing telomerase, triggers the extension of telomer via addition of specific sequence (TTAGGG)n to its 3′ end. Fluorescence, best measured at excitation/emission wavelengths of 390/446 nm, is subsequently restored due to folding of the extended telomeric sequence into G-quadruplex structure. The method was applied to the determination of telomerase activity in crude cell extracts of as little as 10 HeLa cells. The linear dynamic range extends from 10 to 6500 cells.
关键词： G-quadruplex,Biosensors,Fluorescence,Optical sensing,Biomarker,Cancer detection,Nanoprobe
更新于2025-09-12 10:27:22
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Analyte transport to micro- and nano-plasmonic structures
摘要： The study of optical affinity biosensors based on plasmonic nanostructures has received significant attention in recent years. The sensing surfaces of these biosensors have complex architectures, often composed of localized regions of high sensitivity (electromagnetic hot spots) dispersed along a dielectric substrate having little to no sensitivity. Under conditions such that the sensitive regions are selectively functionalized and the remaining regions passivated, the rate of analyte capture (and thus the sensing performance) will have a strong dependence on the nanoplasmonic architecture. Outside of a few recent studies, there has been little discussion on how changes to a nanoplasmonic architecture will affect the rate of analyte transport. We recently proposed an analytical model to predict transport to such complex architectures; however, those results were based on numerical simulation and to date, have only been partially verified. In this study we measure the characteristics of analyte transport across a wide range of plasmonic structures, varying both in the composition of their base plasmonic element (microwires, nanodisks, and nanorods) and the packing density of such elements. We functionalized each structure with nucleic acid-based bioreceptors, where for each structure we used analyte/receptor sequences as to maintain a Damk?hler number close to unity. This method allows to extract both kinetic (in the form of association and dissociation constants) and analyte transport parameters (in the form of a mass transfer coefficient) from sensorgrams taken from each substrate. We show that, despite having large differences in optical characteristics, measured rates of analyte transport for all plasmonic structures match very well to predictions using our previously proposed model. These results highlight that, along with optical characteristics, analyte transport plays a large role in the overall sensing performance of a nanoplasmonic biosensor.
关键词： mass transfer coefficient,analyte transport,plasmonic nanostructures,nanoplasmonic architecture,optical affinity biosensors
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Lossy Mode Resonance Fiber-Optic Biosensing Allowing Ultra-Low Detection Limit
摘要： Fiber-optic biosensors can offer great advantages over other optical technology platforms thanks to the typical features of optical fibers. Moreover, the opportunity of depositing nm-thick overlays on optical fibers with a high degree of accuracy, repeatability and reproducibility has enabled spreading the application domains of this technology. Recently, the concept of guided mode resonance has been exploited in thin film coated fiber-optic sensors, under the name of lossy mode resonance (LMR). LMR occurs when the real part of the thin film permittivity is positive and greater in magnitude than both its own imaginary part and the permittivity of the material surrounding the thin film. Therefore, metallic oxides and polymers can be used to generate LMRs, instead of the noble metals typically used in SPR devices. Instead of using multi-mode fibers, D-shaped single-mode fibers have been used to excite LMR, which enables tracking the spectral displacement of the 1st LMR, the most sensitive LMR, at wavelengths in the NIR, where the sensitivity is enhanced if compared to the visible region. By coating the D-shaped region of the fiber with a nanometric layer of tin oxide (SnO2) and integrating it into an ad-hoc microfluidic system, an ultra-low detection limit (LOD) biosensing device has been developed. The sensing principle is quite simple: when the target analyte interacts with the fiber-functionalized surface, this induces a change in the optical properties of the overlay (i.e. effective refractive index and thickness); in turn, this causes a change in the spectral position of the LMR that can be accurately and precisely measured through a conventional wavelength interrogation system. The deposition of the tin oxide layer (roughly 160-180 nm), which is performed with a DC sputter machine (ND-SCS200, Nadetech S.L.), has been characterized by FESEM images (UltraPlus Carl Zeiss Inc.). The round inset of the same figure details the functionalization of the sensitive region, which is carried out with the deposition of a nm-thick polymeric layer of poly(methyl-methacrylate) (Eudragit L100) that provides free functionalities necessary for the IgG antibody immobilization. The assay has been completed by spiking increasing concentrations of anti-IgG antigen (from 1 pg mL-1 up to 10 μg mL-1) in a real sample of CRP-free human serum. The real-time tracking of the LMR shift has enabled following all the biochemical steps during the assay implementation and then the calibration curve (n=4) of the proposed biosensor has been obtained, together with the sigmoidal fit with the Hill function, which is a well-accepted mathematical model used to quantify the degree of interaction between ligand binding sites. A LOD of 150 fg mL-1 has been attained. This result has confirmed a big leap in performance thanks to the capability to detect analyte concentrations down to few fM in real samples, enhancing the LOD by three orders of magnitude when compared with other fiber-based configurations and matching a LOD comparable with the most outstanding optical technology platforms.
关键词： Fiber-optic biosensors,lossy mode resonance,microfluidic system,ultra-low detection limit,tin oxide
更新于2025-09-11 14:15:04
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Detection of Tumor Marker Using ZnO@Reduced Graphene Oxide Decorated with Alkaline Phosphatase-Labelled Magnetic Beads
摘要： Magnetic bead-based electrochemical enzyme-linked immunoassay (MB-eElisa) represents an attractive approach to develop cost-effective systems that are suitable for sensing complex biological samples. Its sensitivity essentially depends on the transduction efficiency of enzyme catalytic reactions into electrochemical responses. Here, an ultrahigh signal-to-noise alkaline phosphatase (ALP)-based MB-eElisa system is developed with a renewable zinc oxide-reduced graphene oxide nanocomposite modified carbon paste electrode (ZnO@rGO/CPE). This biosensing system employs one antibody decorated MBs (MB-Ab1) to capture a model tumor marker - carcinoembryonic antigen (CEA) - from samples, while other antibody coated gold nanoparticles-ALP bioconjugates (Ab2-AuNPs-ALP) convert 1-naphthyl phosphate (1-NPP) into electroactive 1-naphthol (1-NP). Beneficial from the unique electrochemical properties of a ZnO@rGO/CPE, inlcuding nearly zero background and significantly enhanced responses toward the hydrolyzed 1-NP in the presence of trace surfactants, the MB-eElisa system detects selectively CEA in a calibration range of 0.01-6.0 ng mL-1 and with a detection limit of 4.0 pg mL-1 (S/N = 3). Such a system was further applied to the detection of CEA in serum samples of cancer patients. The combination of MB-based ALP-linked immunoassay with a ZnO@rGO/CPE thus establishes a reusable and inexpensive electrochemical sensing platform for the rapid and sensitive detection of ultratrace biomarkers in complex biological samples.
关键词： Enzyme-linked immunoassay,Carcinoembryonic antigen,Alkaline phosphatase,Magnetic beads,Electrochemical biosensors
更新于2025-09-11 14:15:04
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A disposable microfluidic-integrated hand-held plasmonic platform for protein detection
摘要： Healthcare is in the midst of a transformative shift from centralized care to point-of-care (POC). In this regard, recent efforts have focused on integration of biosensing technologies with clinical management and existing healthcare systems to improve the effectiveness and quality of care. Plasmonic technologies in particular, have been used for multiple applications in biosensing, pharmaceutical industry, food quality monitoring, and healthcare. However, bulky-sized platforms, expensive instrumentation, incomprehensive benchmarking, laborious protocols, and time-consuming processing steps remain challenges to adopt biosensing platforms to the POC settings. Here, we present a hand-held biosensing platform that integrates a plasmonic detection modality with a microfluidic chip. As a biological target model, we assess hemoglobin—an iron carrying protein in red blood cells. We comprehensively perform theoretical simulations and kinetic calculations to benchmark the platform performance. Overall, this miniaturized platform provides label-free detection, simple configuration for user-interface, facile sampling, assay-time down to 15–30 min, and inexpensive disposable chips. Therefore, this platform will potentially accelerate the deployment of portable biosensing systems for the POC and primary care settings.
关键词： Microfluidics,Point-of-care,Plasmonic sensors,Hemoglobin,Portable biosensors
更新于2025-09-11 14:15:04
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Graphene-Based Biosensors for Detection of Composite Vibrational Fingerprints in the Mid-Infrared Region
摘要： In this study, a label-free multi-resonant graphene-based biosensor with periodic graphene nanoribbons is proposed for detection of composite vibrational ?ngerprints in the mid-infrared range. The multiple vibrational signals of biomolecules are simultaneously enhanced and detected by di?erent resonances in the transmission spectrum. Each of the transmission dips can be independently tuned by altering the gating voltage applied on the corresponding graphene nanoribbon. Geometric parameters are investigated and optimized to obtain excellent sensing performance. Limit of detection is also evaluated in an approximation way. Besides, the biosensor can operate in a wide range of incident angles. Electric ?eld intensity distributions are depicted to reveal the physical insight. Moreover, another biosensor based on periodic graphene nanodisks is further proposed, whose performance is insensitive to the polarization of incidence. Our research may have a potential for designing graphene-based biosensor used in many promising bioanalytical and pharmaceutical applications.
关键词： nanophotonics,label-free biosensors,surface plasmons,graphene,metasurface
更新于2025-09-11 14:15:04
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Plasmonic Biosensors on a Chip for Point-of-Care Applications
摘要： Plasmonic biosensors, mainly those based on plasmonics technology, have emerged recently as a possible solution for disease diagnostics at the point-of-care (POC) level. There is an increasing demand for cost-effective, affordable, and robust POC platforms for the diagnosis of infectious and chronic diseases. These platforms should also need only low-sample consumption and be capable of providing a real-time response with a high sensitivity. A biosensor platform, employing small integrated devices, could perform rapid, label-free assays.
关键词： LSPR,microfluidic devices,Plasmonic biosensors,SPR,point-of-care
更新于2025-09-11 14:15:04
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Handbook of Graphene || Self‐Assembled Thin Films of Graphene Materials for Sensors
摘要： It is well known that graphene and its derivatives exhibit unique optical, electrical, mechanical, and chemical properties, which are valuable for sensing applications. However, the chosen methods to synthesize and process graphene to form the sensing unit are critical steps defining the real property of the final sensor. Instead of a physical mixture of graphene in a bulk support, different immobilization techniques have been investigated to take advantage of the outstanding properties of graphene and graphene-based materials, such as linkage to the self-assembled monolayers, layer-by-layer, and Langmuir–Blodgett techniques. Such techniques lead to a new concept of nanoarchitectonics allowing to take a synergistic effect on mixing distinct properties with various materials in a unique device. Examples of these approaches on developing electrochemical, electric, and optical sensors are discussed in an overview.
关键词： chemical synthesis,self-assembled monolayers,Sensors,layer-by-layer,Langmuir–Blodgett,biosensors
更新于2025-09-11 14:15:04