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Human chorionic gonadotropin (hCG), a glycoprotein hormone secreted from the placenta, is a key molecule that indicates pregnancy. Here, we have designed a cost-effective, label-free, in situ point-of-care (POC) immunosensor to estimate hCG using a cuneated 25 nm polysilicon nanogap electrode. A tiny chip with the dimensions of 20.5 × 12.5 mm was f...
Citations
... For example, portable glucose meters for monitoring blood sugar levels in diabetes patients and early pregnancy test kits are important achievements that have been a driving force in the development of personalized point-of-care medicine [9,10]. An important goal to pave the way for simple access to point-of-care diagnostics is related to the development of liquid biopsy diagnostic devices with the attempt to provide valid, non-invasive, and reliable assays identifying biomarkers from body fluids. ...
For the progress of point-of-care medicine, where individual health status can be easily and quickly monitored using a handheld sensor, saliva serves as one of the best-suited body fluids thanks to its availability and abundance of physiological indicators. Salivary biomarkers, combined with rapid and highly sensitive detection tools, may pave the way to new real-time health monitoring and personalized preventative therapy branches using saliva as a target matrix. Saliva is increasing in importance in liquid biopsy, a non-invasive approach that helps physicians diagnose and characterize specific diseases in patients. Here, we propose a proof-of-concept study combining the unique specificity in biomolecular recognition provided by surface-enhanced Raman spectroscopy (SERS) in combination with molecular dynamics (MD) simulations, which give leave to explore the biomolecular absorption mechanism on nanoparticle surfaces, in order to verify the traceability of two validated salivary indicators, i.e., interleukin-8 (IL-8) and lysozyme (LYZ), implicated in oropharyngeal squamous cell carcinoma (OSCC) and oral infection. This strategy simultaneously assures the detection and interpretation of protein biomarkers in saliva, ultimately opening a new route for the evolution of fast and accurate point-of-care SERS-based sensors of interest in precision medicine diagnostics.
... Balakrishnan et al. [85]used standard semiconducting materials with silicon as the substrate and polysilicon (PS) as the sensing electrode to detect hCG [85]. The hCG antibodies were immobilized on a polysilicon nanogap (PSNG) electrodes. ...
... Balakrishnan et al. [85]used standard semiconducting materials with silicon as the substrate and polysilicon (PS) as the sensing electrode to detect hCG [85]. The hCG antibodies were immobilized on a polysilicon nanogap (PSNG) electrodes. ...
... In such a scenario, sensor currents of ~21 μA and ~11 μA indicate the absence and presence of HPV-16 infection, respectively. The LoD of the flexible HPV-16 sensor was calculated to be ~2 pM using the well-established 3σ rule [38]. Table 1 highlights a comparison of few parameters of the CSPE/rGO/PDNA platform with a few reported ones. ...
Human Papilloma Virus 16 (HPV 16) is the well-known causative species responsible for triggering cervical cancer. When left undiagnosed and untreated, this disease leads to life-threatening events among the female populace, especially in developing nations where healthcare resources are already being stretched to their limits. Considering various drawbacks of conventional techniques for diagnosing this highly malignant cancer, it becomes imperative to develop miniaturized biosensing platforms which can aid in early detection of cervical cancer for enhanced patient outcomes. The current study reports on the development of an electrochemical biosensor based on reduced graphene oxide (rGO)/DNA hybrid modified flexible carbon screen-printed electrode (CSPE) for the detection of HPV 16. The carbon-coated SPEs were initially coated with rGO followed by probe DNA (PDNA) immobilization. The nanostructure characterization was performed using UV-Vis spectroscopy, Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy and X-ray diffraction (XRD) techniques. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were employed to study the electrochemical characterization of the nano-biohybrid sensor surface. The optimization studies and analytical performance were assessed using differential pulse voltammetry (DPV), eventually exhibiting a limit of detection (LoD) ~2 pM. The developed sensor was found to be selective solely to HPV 16 target DNA and exhibited a shelf life of 1 month. The performance of the developed flexible sensor further exhibited a promising response in spiked serum samples, which validates its application in future point-of-care scenarios.
... The developed immunosensor provided a linear detection range of 1 fM to 1 µM. The calculated LoD from the 3σ rule was about 0.69 fM [29] and the sensitivity was calculated to be 0.14 kΩ/nM/mm 2 [30]. Figure 5a shows the Nyquist spectra recorded at various concentration ranges of PT (1 fM to 1 µM) in the frequency range of 100 Hz to 50 kHz at an ac amplitude of 10 mV measured in the presence of 0.1 M PBS buffer. ...
... The developed immunosensor provided a linear detection range of 1 fM to 1 µM. The calculated LoD from the 3σ rule was about 0.69 fM [29] and the sensitivity was calculated to be 0.14 kΩ/nM/mm 2 [30]. Figure 6 shows the selectivity of the fabricated sensor. ...
The extensive use of organophosphates (OPs) pollutes the environment, leading to serious health hazards for human beings. The current need is to fabricate a sensing platform that will be sensitive and selective towards the detection of OPs at trace levels in the nM to fM range. With this discussed in the present report, an ultra-sensitive immunosensing platform is developed using digestive-ripened copper oxide quantum dots grafted on a gold microelectrode (Au-µE) for the impedimetric detection of parathion (PT). The copper oxide quantum dots utilized in this study were of ultra-small size with a radius of approximately 2 to 3 nm and were monodispersed with readily available functional groups for the potential immobilization of antibody parathion (Anti-PT). The miniaturization is achieved by the utilization of Au-µE and the microfluidic platform utilized has the sample holding capacity of about 2 to 10 µL. The developed immunosensor provided a wide linear range of detection from 1 µM to 1 fM. The lower Limit of Detection (LoD) for the developed sensing platform was calculated to be 0.69 fM, with the sensitivity calculated to be 0.14 kΩ/nM/mm2. The stability of the sensor was found to be ~40 days with good selectivity. The developed sensor has the potential to integrate with a portable device for field applications.
... In such a scenario, a sensor current of ~24.7 µA and ~ 50 µA indicates normal acetylcholine in ganglionic (normal) cells, and abnormally high acetylcholine in aganglionic segments respectively with the latter indicating the occurrence of HD. The Limit of Detection (LoD) and sensitivity of the developed sensor were calculated to be 0.19 µM (using 3σ rule) and 0.42 µA/µM/mm 2 respectively [37]. ...
Hirschsprung’s disease (HD) is characterised by missing nerve cells in the colon of infants and children which results in strained bowel movement. Under such situations, undiagnosed and untreated cases often lead to gastrointestinal infections eventually resulting in Hirschsprung‐assisted enterocolitis which has significantly high mortality rate. The present work reports an electrochemical enzymatic biosensor using Zeolitic Imidazolate Framework‐8 modified with acetylcholinesterase, for management of HD by detecting the key biomarker – acetylcholine. The developed sensor was selective to acetylcholine with LoD and shelf life of 0.19 uM and 1 month respectively, while exhibiting superior performance in spiked serum.
... [124] Figure 9A shows a point of care immunosensor. [125] It uses a polysilicon nanogap electrode which is connected to microfluidics channels provides amperometric characteristics and sensitivity data for the immunosensor. Another important biomarker is cholesterol. ...
... The right graph shows the results of DC amperometric detection of urine samples against standard reference samples based on electrical capacitance measurements. Reproduced under the terms and conditions of the Creative Commons Attribution license.[125] Copyright 2015, The Authors. ...
Micro/nanofluidic devices and systems have attracted ever-growing attention in healthcare applications over the past decades due to low-cost yet easy-customizable functions with the demand of only a small volume of sample fluid. The continuous development, in particular, supported by the emergence of new materials, capable of meeting critical needs in next-generation, wearable, and multifunctional biomedical devices for at-home, personalized healthcare monitoring, is challenging the principles and strategies of structural design, manufacturing, and their seamless integration. This review summarizes the progress in micro/nanofluidic-enabled biomedical devices with a focus on structural design, manufacturing, and applications in healthcare. Structures of fluidic channels and liquid actuation strength are given to elucidate the manipulations and controls of fluid transports that help capture desirable information of interest, including component separation, extraction, measurements, and disease diagnoses. Manufacturing processes of fluidic devices in micro- and nanoscales and their basic working principles are also presented, ranging from lithography in traditional hard materials to 3D printing in emerging soft materials. The selected examples and demonstrations are illustrated to highlight applications of biomedical fluidic devices in a broad variety of disease detection and diagnosis. The associated challenges and future opportunities are discussed.
... These values correspond to a frequency of 10 Hz, at which each sensor was calibrated as shown in figures 3 (D)-(F), thereby establishing a linear nature and inverse proportionality between Z ′ (R ct ) and TYR concentration (c). Table 1 shows the LoD and the sensitivity calculated for each sensing surfaces [40]. It can be observed that surface S1, which exhibited the most rapid electron transfer kinetics, possessed the lowest LoD and highest sensitivity as compared to S2 and S3. ...
Electrochemical biosensors employing nano-transduction surfaces are considered highly sensitive to the morphology of nanomaterials. Various interfacial parameters namely charge transfer resistance, double layer capacitance, heterogeneous electron transfer rate and diffusion limited processes, depend strongly on the nanostructure geometry which eventually affects the biosensor performance. The present work deals with a comparative study of electrochemical impedance-based detection of L-tyrosine (or simply tyrosine) by employing carbon nanostructures (graphene quantum dots, single walled carbon nanotubes (CNTs) and graphene) along with tyrosinase as the bio-receptor. Specifically, the role of carbon nanostructures (i.e. 0D, 1D and 2D) on charge transfer resistance is investigated by applying time-varying electric field at the nano-bioelectrode followed by calculating the heterogeneous electron transfer rate, double layer capacitor current and their effects on limits of detection and sensitivities towards tyrosine recognition. A theoretical model based on Randel’s equivalent circuit is proposed to account for the redox kinetics at various carbon nanostructure/enzyme hybrid surfaces. It was observed that, the 1D morphology (single walled CNTs) exhibited lowest charge transfer resistance ∼2.62 kΩ (lowest detection limit of 0.61 nM) and highest electron transfer rate ∼0.35 μm s ⁻¹ (highest sensitivity 0.37 kΩ nM ⁻¹ mm ⁻² ). Our results suggest that a suitable morphology of carbon nanostructure would be essential for efficient and sensitive detection of tyrosine.
... This process increases rapidly at higher Pb 2+ concentrations due to a greater degree of Pb 2+ adsorption onto the surface oxygen species, which act as Lewis acids by accepting more electrons [28] (leading to enhanced electron exchange between Mn and Pb), and ultimately decreasing the sensor resistance to 90 kΩ at 1 μM Pb(II). The LoD (using the conventional 3σ rule) and sensitivity of the portable Pb(II) sensing device was calculated to be 0.81 nM and 1.05 kΩ/nM/mm 2 , respectively [32]. ...
The occurrence of heavy metal ions in food chain is appearing to be a major problem for mankind. The traces of heavy metals, especially Pb(II) or Pb2+ present in water bodies remains undetected, untreated and it remains in food cycle which causes serious health hazards for human and livestock. The consumption of Pb(II) ions may lead to serious medical complications including multiple organ failure which can be fatal the conventional methods of heavy metal detection are costly, time consuming and requires laboratory space there is an immediate need to develop a cost effective and portable sensing system. In this work, an attempt is made to develop a Pb(II) sensing system with miniaturized electronics, based on microfluidic platform, employing nanocomposites of α-MnO2 and Graphene Quantum Dots (α-MnO2/GQD) which can be easily integrated with the miniaturized electronics for real-time on-field applications. The developed portable sensor required low sample volume (200µL) and was assessed within Pb(II) concentration range of 0.001 nM to 1 uM. The calculated Limit of Detection (LoD) and sensitivity was calculated to be 0.81 nM and 1.05 kΩ/nM/mm2, and was validated with commercial impedance analyzer. The shelf-life of the portable sensor was found to be ~ 45 days.
... The elected multiple junction triangles sensor is the electrical-based biosensing system to recognize various biomolecular interactions on the electrode surface through the response of current. [8][9][10] It offers several advantages such as label-free, low-power, low-cost, portable, higher sensitivity and easy to use. Numerous devices with nanogap/microgap have been fabricated with various techniques and reported by researchers for biosensing applications. ...
Background
In recent years, nanomaterials have justified their dissemination for biosensor application towards the sensitive and selective detections of clinical biomarkers at the lower levels. MXene is a two-dimensional layered transition metal, attractive for biosensing due to its chemical, physical and electrical properties along with the biocompatibility.
Materials and Methods
This work was focused on diagnosing osteosarcoma (OS), a common bone cancer, on MXene-modified multiple junction triangles by dielectrode sensing. Survivin protein gene is highly correlated with OS, identified on this sensing surface. Capture DNA was immobilized on MXene by using 3-glycidoxypropyltrimethoxysilane as an amine linker and duplexed by the target DNA sequence.
Results
The limitation and sensitivity of detection were found as 1 fM with the acceptable regression co-efficient value (y=1.0037⨰ + 0.525; R²=0.978) and the current enhancement was noted when increasing the target DNA concentrations. Moreover, the control sequences of single- and triple-mismatched and noncomplementary to the target DNA sequences failed to hybridize on the capture DNA, confirming the specificity. In addition, different batches were prepared with capture probe immobilized sensing surfaces and proved the efficient reproducibility.
Conclusion
This microgap device with Mxene-modified multiple junction triangles dielectrode surface is beneficial to quantify the survivin gene at its lower level and diagnosing OS complication levels.
... The regression line equation of calibration plot was calculated to be Rct (kΩ) = 3.367 log CCPF (ng/L) + 9.695 and R 2 = 0.984. The Limit of Detection (LoD) and sensitivity was calculated to be 3 ng/L and 0.521 kΩ/ng L -1 /mm 2 respectively [35]. ...
The use of pesticides in agriculture field remains a serious issue related to public health. This necessitates the need to develop a low cost/portable, sensitive and selective bio-sensing platform for detection of pesticides in food chain. In this work a low-cost biosensing platform for ultrasensitive detection of chlorpyrifos (CPF) is developed. Electrochemical micro Paper Analytical Device (ElPAD) is fabricated by conventional screen-printing technology. Metal Organic Framework (Z1200 MOF) having zinc metal and imidazole ligand is used as a transducing element which facilitates biocompatible matrix for Acetylcholinesterase (AChE) enzyme immobilization. The limit of detection for CPF is found be 3 ng/L with sensitivity 0.521 kY/ng L-1/mm2. The sensor required 100lL of reagent and was tested with a linear concentration range of 10 ng/L to 1000 ng/L with response time of 5s. The sensor is further integrated with portable electronics based on Arduino microcontroller and Artificial Intelligence (AI) which provided economical, portable and user-friendly sensing platform. The stability of the sensor was 30 days. The developed sensor was also tested with real samples and the sensor response is in agreement with conventional technique.
