Label-free Biosensor Research Articles

Label-free biosensor assay decodes the dynamics of Toll-like receptor signaling.

The discovery of Toll-like receptors (TLRs) represented a significant breakthrough that paved the way for the study of host-pathogen interactions in innate immunity. However, there are still major gaps in understanding TLR function, especially regarding the early dynamics of downstream TLR pathways. Here, we present a label-free optical biosensor-based assay as a method for detecting TLR activation in a native and label-free environment and defining the dynamics of TLR pathway activation. This technology is sufficiently sensitive to detect TLR signaling and readily discriminates between different TLR signaling pathways. We define pharmacological modulators of cell surface and endosomal TLRs and downstream signaling molecules and uncover TLR signaling signatures, including potential biased receptor signaling. These findings highlight that optical biosensor assays complement traditional assays that use a single endpoint and have the potential to facilitate the future design of selective drugs targeting TLRs and their downstream effector cascades.

A novel label-free impedance biosensor for KRAS G12C mutations detection based on PET-RAFT and ROP synergistic signal amplification

The KRAS G12C mutations, as crucial biomarkers, are closely associated with non-small cell lung cancer. Here, a novel label-free electrochemical biosensor with synergistic signal amplification of photocell energy transfer-reversible addition fragmentation chain transfer (PET-RAFT) and ring-opening polymerization (ROP) was developed for the first time for sensitive detection of KRAS G12C mutations. Specifically, hairpin DNA (hDNA), which act as biomolecular probe, was self-assembled on Au electrode surface by Au-S bond. 4-cyano-4-[(dodecylsulfanylthiocarbonyl) sulfanyl] pentanoic acid (CDTPA), the chain transfer agent of PET-RAFT reaction, was then attached to hDNA via amide bond. After that, the target DNA (tDNA) was captured on the electrode surface by complementary base pairing with hDNA. Subsequently, large numbers of electro-active monomers N-acryloxysuccinimide (NAS) were successfully grafted to the electrode surface via PET-RAFT reaction, which provided plenty of junction sites for doxorubicin-polycaprolactone (Dox-PCL) synthesized by ROP. Finally, the Dox-PCL was connected to the electrode surface by ester bond, significantly amplifying the electrochemical signal. Under optimized conditions, the biosensor has a wide linear detection range of 0.1 pM to 1 μM, with a detection limit of 86.9 fM. Attribute to its high sensitivity, specificity, reproducibility and stability, this biosensor possesses considerable potential in early diagnosis of disease and biomedical research.

Label-free electrochemical biosensor with magnetic self-assembly constructed via PNA-DNA hybridization process on α-Fe2O3/Fe3O4 nanosheets for APOE ε4 genes ultrasensitive detection

Label-free electrochemical biosensor with magnetic self-assembly constructed via PNA-DNA hybridization process on α-Fe2O3/Fe3O4 nanosheets for APOE ε4 genes ultrasensitive detection

A Novel PCR-Free Ultrasensitive GQD-Based Label-Free Electrochemical DNA Sensor for Sensitive and Rapid Detection of Francisella tularensis

Biological warfare agents are infectious microorganisms or toxins capable of harming or killing humans. Francisella tularensis is a potential bioterrorism agent that is highly infectious, even at very low doses. Biosensors for biological warfare agents are simple yet reliable point-of-care analytical tools. Developing highly sensitive, reliable, and cost-effective label-free DNA biosensors poses significant challenges, particularly when utilizing traditional techniques such as fluorescence, electrochemical methods, and others. These challenges arise primarily due to the need for labeling, enzymes, or complex modifications, which can complicate the design and implementation of biosensors. In this study, we fabricated Graphene Quantum dot (GQD)-functionalized biosensors for highly sensitive label-free DNA detection. GQDs were immobilized on the surface of screen-printed gold electrodes via mercaptoacetic acid with a thiol group. The single-stranded DNA (ssDNA) probe was also immobilized on GQDs through strong π−π interactions. The ssDNA probe can hybridize with the ssDNA target and form double-stranded DNA, leading to a decrease in the effect of GQD but a positive shift associated with the increase in DNA concentration. The specificity of the developed system was observed with different microorganism target DNAs and up to three-base mismatches in the target DNA, effectively distinguishing the target DNA. The response time for the target DNA molecule is approximately 1010 s (17 min). Experimental steps were monitored using UV/Vis spectroscopy, Atomic Force Microscopy (AFM), and electrochemical techniques to confirm the successful fabrication of the biosensor. The detection limit can reach 0.1 nM, which is two–five orders of magnitude lower than previously reported methods. The biosensor also exhibits a good linear range from 105 to 0.01 nM and has good specificity. The biosensor’s detection limit (LOD) was evaluated as 0.1 nM from the standard calibration curve, with a correlation coefficient of R2 = 0.9712, showing a good linear range and specificity. Here, we demonstrate a cost-effective, GQD-based SPGE/F. tularensis DNA test suitable for portable electrochemical devices. This application provides good perspectives for point-of-care portable electrochemical devices that integrate sample processing and detection into a single cartridge without requiring a PCR before detection. Based on these results, it can be concluded that this is the first enzyme-free electrochemical DNA biosensor developed for the rapid and sensitive detection of F. tularensis, leveraging the nanoenzyme and catalytic properties of GQDs.

Free Electron Density Gradients Enhanced Biosensor for Ultrasensitive and Accurate Affinity Assessment of the Immunotherapy Drugs.

Accurate affinity assessments play an important role in drug discovery, screening, and efficacy evaluation. Label-free affinity biosensors are recognized as a dependable and standard technology for addressing this challenge. This study constructs a free electron density gradient-enhanced meta-surface plasmon resonance (FED-MSPR) biosensor through a finite-difference time-domain simulation model, the biosensor demonstrates superior detection performance in accurately determining affinity and kinetic rate constants. By controlling the dielectric properties of the metal on the surface of the nanocup arrays, the plasmon resonance effects are easily tuned without changing the nanostructure design. Compared with the single-layer gold chip, the triple-layer FED-MSPR chip demonstrated a four-fold improvement in resolution at the optimal resonance peak. Additionally, the sensitivity and figure of merit (FOM) of the multi-layer chip increased by 3.5 and 7.99 times, respectively. Following modification with high- and low-staggered carboxylation, the noise-signal ratio and baseline stability of the real-time kinetic curves based on these chips are significantly enhanced. The developed carboxylation FED-MSPR platform is successfully used to perform affinity assays for Adalimumab and TNF-α protein, resulting in favorable dynamic curves. These findings validate the proposed FED-MSPR biosensor platform as cost-effective, rapid, sensitive, and label-free, facilitating real-time quality control in drug development.

Dielectric Modulated Nanotube Tunnel Field-Effect Transistor with Core-Shell Cavity as a Label-Free Biosensor: Proposal and Analysis.

Dielectric Modulated Field-Effect Transistors (DMFETs) have emerged as promising candidates for label-free bioanalyte detection. However, the inherent short-channel effects in conventional DMFETs increase their static power dissipation significantly and limit their scalability and sensitivity. Therefore, FETs based on alternate conduction mechanism such as tunneling (TFETs), which are immune to the short-channel effects, appear to be a lucrative alternative to the MOSFETs for biosensing application. In this work, we propose a novel Dual Cavity Dielectric Modulated Nanotube Tunnel FET (DCDM NTTFET)-based label-free biosensor consisting of a Ge source and nanocavities within the core as well as a shell gate stack, which not only outperforms the conventional MOSFET and advanced nanowire (NW) TFET-based biosensors in terms of energy-efficiency and scalability but also exhibits a significantly high drain current sensitivity (SION = 2.9 × 108) and a threshold voltage sensitivity (SVth = 0.85), and a considerably high selectivity of more than 6 orders of magnitude. We also perform a comprehensive design space exploration for the proposed DCDM NTTFET and provide necessary design guidelines to further improve its performance considering the practical artifacts such as steric hindrance.

Bioreceptors’ immobilization by hydrogen bonding interactions and differential pulse voltammetry for completely label-free electrochemical biosensors

Label-free electrochemical biosensors show great potential for the development of point-of-care devices (POCDs) for environmental and clinical applications. These sensors operate with shorter analysis times and are more economic than the labelled ones. Here, four completely label-free biosensors without electron transfer mediators were developed for hepatitis B virus (HBV) detection. The approach consisted in (i) the modification of gold surfaces with cysteamine (CT) or cysteine (CS) linkers, (ii) the subsequent antibody (Ab) immobilization, either directly by hydrogen bonding (HB) interactions or by covalent bonds (CB) using additional reagents, and (iii) measuring the biosensor response by electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV). The electrode surfaces at each stage of the modification process were characterised by X-ray photo-electron spectroscopy (XPS) and atomic force microscopy (AFM). The combination of Ab immobilization by HB with the DPV analysis displayed improved repeatability, lower interference to serum matrix and similar limits of detection and quantification than the traditional biosensors that immobilize the Ab via CB and use EIS as readout technique. The Ab immobilization by HB is shown as a simple, efficient and low-cost alternative to CB ones, while DPV was faster and showed better performance than EIS. The CT-HB biosensor displayed the lowest limits of detection and quantification of 0.14 and 0.46 ng/mL, respectively, a 0.46–12.5 ng/mL linear analytical range, and 100% of recovery for 1/10 human serum media during HBV surface antigen detection by DPV. Even, it preserved the initial sensing capability after 7 days of its fabrication.Graphical abstract

Cell membrane-inspired COF/AAO hybrid nanofluidic membrane with ion current rectification properties for ultrasensitive detection of E. coli

Nanofluidic membranes hold great prospects in sensitive and rapid detection of bioanalysts, while remaining lacking robust and general approaches for specificity. In this work, we introduce a cell membrane-inspired nanofluidic membrane with excellent ion current rectification properties as a simple and robust platform for label-free and ultrasensitive biosensing. The asymmetric nanofluidic membrane is prepared by coupling a two-dimensional covalent organic framework (COF) membrane to an anodic aluminum oxide (AAO) nanochannel via hydrogen bonding. The prepared COF/AAO membrane presents selective ion transport due to the asymmetric structure and anion selectivity of COF. With the large surface area and abundant functional modification sites of COF, further grafting of the recognition unit can be easily achieved to mimic the recognition process of receptors and ligands on cell membranes. As a proof of concept, the application in bacterial detection is demonstrated by covalently bonded Concanavalin A as recognition units. The highly amplified ionic current based on ion current rectification properties of the COF/AAO membrane allows sensitive and selective bioanalysis. Specifically, the proposed asymmetric nanofluidic membrane presents a linear detection range from 10 to 106 CFU/mL with an ultralow detection limit of 7 CFU/mL for E. coli. This work reveals the great potential of COF/AAO hybrid nanofluidic membrane as a sensor for rapid and precise bioanalysis.

Double-layer optical fiber interferometer with bio-layer-modified reflector for label-free biosensing of inflammatory proteins

This work discusses label-free biosensing application of a double-layer optical fiber interferometer where the second layer tailors the reflection conditions at the external plain and supports changes in reflected optical spectrum when a bio-layer binds to it. The double-layer nanostructure consists of precisely tailored thin films, i.e., titanium (TiO2) and hafnium oxides (HfO2) deposited on single-mode fiber end-face by magnetron sputtering. It has been shown numerically and experimentally that the approach besides well spectrally defined interference pattern distinguishes refractive index (RI) changes taking place in a volume and on the sensor surface. These are of interest when label-free biosensing applications are considered. The case of myeloperoxidase (MPO) detection—a protein, which concentration rises during inflammation—is reported as an example of application. The response of the sensor to MPO in a concentration range of 1 × 10−11–5 × 10−6 g/mL was tested. An increase in the MPO concentration was followed by a redshift of the interference pattern and a decrease in reflected power. The negative control performed using ferritin proved specificity of the sensor. The results reported in this work indicate capability of the approach for diagnostic label-free biosensing, possibly also at in vivo conditions.

Silicon Nanowire Biosensors for Diabetes Mellitus Monitoring

The main goal of this research is the development of a label-free biosensor for the detection of diabetes mellitus (DM) using the target molecule retinol-binding protein 4 (RBP4). The enzyme-linked immunosorbent assay (ELISA) approach, currently used to detect DM, is time-consuming and difficult. As a result, label-free biosensors are being considered as an alternative. In this research, silicon nanowires (SiNWs) were selected as the transducer for this biosensor due to their low cost, real-time analysis capability, high sensitivity, and low detection limit. The SiNWs were created using conventional lithography, reactive ion etching (RIE), and physical vapor deposition (PVD), and then dripped with a gold nanoparticle solution to create gold-decorated SiNWs. The surface of the gold-decorated SiNWs was functionalized using 3-aminothiophenol and glutaraldehyde solutions before being immobilized with DM RBP4 antibodies and targets. The electrical characterization of the gold nanoparticle decorated SiNWs biosensor revealed good performance in DM detection. The pH tests confirmed that the SiNWs acted as a transducer, with current proportional to the DM RBP4 concentration. The estimated limit of detection (LOD) and sensitivity for detecting DM RBP4 binding were 0.076 fg/mL and 8.92 nA(g/mL)-1, respectively. This gold nanoparticle decorated SiNWs biosensor performed better than other methods and enabled efficient, accurate, and direct detection of DM. The SiNWs could be used as a distinctive electrical protein biosensor for biological diagnostic purposes. In conclusion, gold nanoparticle deposition offers effective label-free, direct, and high-accuracy DM detection, outperforming previous approaches. Thus, these SiNWs serve as novel electrical protein biosensors for future biological diagnostic applications.

Label-free biomolecule detection with dielectrically modulated double gate single cavity InGaAs/GaAsSb HTFET: Design considerations and performance evaluation

Dielectrically Modulated Double Gate Single Cavity InGaAs/GaAsSb HTFET (DMDG–SC–InGaAs/GaAsSb HTFET) is a novel label-free, nanocavity embedded dielectrically modulated heterostructure TFET-based biosensor. The III-V heterostructure (InGaAs/GaAsSb) has a high ION/IOFF ratio, better gate control, and higher tunnelling probability. In order to effectively reduce ambipolarity, asymmetrical doping is used at the p+ source and n+ drain, along with gate work function engineering. The stacked layers of HfO2/SiO2 gate oxide help to reduce the fringing electric field. The suggested device utilizes a dielectrically controlled technique to achieve biomolecule conjugation. This is done by etching a single nanogap cavity in the gate dielectric material towards the source end. An evaluation of the dielectric constants [K = 2.1, 2.63, 3.30, 6.3, and 12] of neutral and charged biomolecules compared to air [k = 1] is essential to determine the sensitivity of biosensors in an arid environment. The transconductance-to-current ratio (gm/Ids), switching ratio (ION/IOFF), and threshold voltage are the performance metrics used to evaluate the device sensitivity. The DM-DG–SC–InGaAs/GaAsSb HTFETpromises to be very sensitive while using less power during the detection process. It also shows that it could be a good choice for label-free biosensor applications.

Performance of label-free biosensors as a function of layer thickness

Performance of label-free biosensors as a function of layer thickness

Performance assessment of SiGe extended four corner source TFET for biosensing applications

In this paper, the performance of a novel SiGe extended four corner source tunneling field–effect transistor (SiGe EFCS TFET) based dielectrically modulated label-free biosensor has been investigated for biosensing applications. Using a combination of heterostructure (SiGe/Si) and extended four corner source (EFCS) lead to increased band–to–band tunneling (BTBT) probability, improved gate control and superior drain current sensitivity for biomolecule conjugation in comparison with a conventional TFET and Si EFCS TFET structures of similar dimensions. The influence of both the charge–neutral and charged biomolecules on the sensitivity performance is investigated using the Silvaco TCAD ATLAS semiconductor device simulator with a calibrated nonlocal BTBT model. Four different kinds of biomolecules such as Streptavidin, Ferro–cytochrome c, Keratin and Gelatin with various charge density values were used for this purpose. In order to model steric hindrance effects in partially filled cavities, in addition to various fill factors, four different step profile patterns have considered such as convex, concave, decreasing and increasing step profiles. Also, the dependence of the nanogap cavity properties on the sensing performance in terms of the length and thickness is investigated. A maximum drain current sensitivity of 1.69 × 105 is achieved in SiGe EFCS TFET for Gelatin biomolecules in a fully filled nanogap cavity at overdrive and drain voltages of 0.5 V.

A label-free strategy for direct detection of Staphylococcus aureus in complex matrixes based on RCA and aptamer

Given the significant threat to human health posed by Staphylococcus aureus, rapid and accurate quantification of S. aureus is essential to prevent and diagnose foodborne diseases and to ensure the safety of food consumption. Here, we developed a novel, simple，and label-free biosensor for quantitatively detecting S. aureus by integrating an allosteric aptamer probe and a rolling circle amplification technique. Pathogen S. aureus-specific binding could induce the structural change of the allosteric aptamer beacon to expose the primer for the padlock probe. Then, the primer could trigger the RCA reaction to produce a long-chain singles-tranded DNA harboring repeating Thioflavin T (ThT) aptamer, leading to powerful fluorescence signals. The assay demonstrates sensitivity, specificity, and accuracy, showing its potential as an alternative tool for pathogen detection in different fields, such as food safety monitoring.

Development of a carboxymethyl chitosan functionalized slide for small molecule detection using oblique-incidence reflectivity difference technology.

Label-free optical biosensors have become powerful tools in the study of biomolecular interactions without the need for labels. High throughput and low detection limit are desirable for rapid and accurate biomolecule detection. The oblique-incidence reflectivity difference (OI-RD) technique is capable of detecting thousands of biomolecular interactions in a high-throughput mode, specifically for biomolecules larger than 1000 Da. In order to enhance the detection capability of OI-RD for small molecules (typically < 500 Da), we have developed a three-dimensional biochip that utilized carboxymethyl chitosan (CMCS) functionalized slides. By investigating various factors such as sonication time, protein immobilization time, CMCS molecular weight, and glutaraldehyde (GA) functionalization time, we have achieved a detection limit of 6.8 pM for avidin (68 kDa). Furthermore, accurate detection of D-biotin with a molecular weight of 244 Da has also been achieved. This paper presents an effective solution for achieving both high throughput and low detection limits using the OI-RD technique in the field of biomolecular interaction detection.

A dendrimer-based platform integrating surface-enhanced Raman scattering and class-incremental learning for rapidly detecting four pathogenic bacteria

Rapid monitoring of pathogens is crucial for preventing foodborne diseases, thus making it an urgent need to develop efficient, fast, and simple methods for on-site detection of multiple pathogens. With advances in SERS-based label-free biosensors and machine learning, progress is evident, yet challenges such as complex substrates and limited model interpretability persist. In this work, we reported a novel dendrimer-based platform that integrated surface-enhanced Raman scattering (SERS) with class-incremental learning (CIL) for quick and simultaneous detection of four pathogenic bacteria, namely Escherichia coli, Salmonella Paratyphi B, Pseudomonas aeruginosa, and Staphylococcus aureus. First, the poly(amidoamine) (PAMAM)-based gold nanoassemblies on silicon wafer (PGNAs/Si) was designed as a highly active SERS substrate with an easy fabrication process. Compared with naked gold nanoparticles, both sensitivity and repeatability were improved by introducing a controllable dendritic nanostructure with ultra-small internal nanogaps. The detection limits of four pathogens in water, food, and dietary supplement matrices were all on the order of 10 CFU/mL. Subsequently, to analyze the complex SERS spectra and distinguish samples with different pathogens, CIL models were established using the light gradient boosting machine (LightGBM) algorithm. Notably, the discriminative models demonstrated excellent classification performance with an accuracy of over 93.44 %. Further, the SHapley Additive exPlanations (SHAP) method was utilized to identify the key SERS features in accurately discriminating different pathogens. Together, these results demonstrate that the dendrimer-based platform, by integrating SERS with CIL, can rapidly detect four pathogenic bacteria, underscoring its potential for food safety testing or quality monitoring in medical supplies manufacturing.

Dielectric Modulated TFET on SELBOX Substrate as a Label-Free Biosensor Applications: Analytical Modeling Study and Sensitivity Analysis

Abstract The manuscript proposes a ferroelectric heterojunction TFET (BG-FE-HJ-STFET) on SELBOX substrates with a back gate to create an ultra-sensitive label-free biosensor with dielectric modulation for the detection of neutral and charged biomolecules. Within the proposed device, four cavities have been carved out for the biomolecules' immobilization under the front and rear gate dielectrics. By using a ferroelectric (FE) material as a gate stack, the low gate voltage is increased to be more effective by causing a negative capacitance phenomenon. The response of the proposed biosensor to four impartial biomolecules with different dielectric constants Protein (k=8), Biotin (k=2.63), 3-Aminopropyl-triethoxysilane (APTES) (k=3.57), and Streptavidin (k=0.1) has been investigated. Deoxyribonucleic acid (DNA), a charged biomolecule, is also examined for dielectric constant of k=6 with respect to both charges (Negative and Positive)) densities. The device is simulated with the commercially available SILVACO ATLASTM TCAD tool. The performance analysis relies on several figures of merit (FOMs) such as DC/RF and sensitivity (including drain current, ION/IOFF ratio, and subthreshold swing) for both neutral and charged biomolecules. The optimized cavity structure demonstrates a notable sensitivity in drain current (2.7x108) and a significant ION/IOFF sensitivity (1.42x1011). One of the main problems with current biosensors is the difficulty and expense of production in the nanoscale realm.

Impedimetric Gram-Positive Bacteria Biosensor Using Vancomycin-Coated Silica Nanoparticles with a Gold Nanocluster-Deposited Electrode.

We introduce a swift, label-free electrochemical biosensor designed for the precise on-site detection of Gram-positive bacteria via electrochemical impedance spectroscopy. The biosensor was prepared by electroplating the electrode surface with gold nanoclusters (AuNCs) on the gold-interdigitated wave-shaped electrode with a printed circuit board (Au-PCB) electrode, which plays a role in cost-effective and promising lab-on-a-chip microsystems and integrated biosensing systems. This was followed by the application of silica nanoparticle-modified vancomycin (SiNPs-VAN) that binds to Gram-positive bacteria and facilitates their detection on the AuNC-coated surface. The biosensor demonstrated remarkable sensitivity and specificity. It could detect as few as 102 colony-forming units (CFU)/mL of Staphylococcus aureus, 101 CFU/mL of Bacillus cereus, and 102 CFU/mL of Micrococcus luteus within 20 min. Additionally, SiNPs-VAN is also known for its high stability, low cost, and ease of preparation. It is effective in identifying Gram-positive bacteria in water samples across a concentration range of 102-105 CFU/mL and shows selective identification of Gram-positive bacteria with minimal interference from Gram-negative bacteria like Escherichia coli. The ability of the biosensor to quantify Gram-positive bacteria aligns well with the results obtained from the quantitative real-time polymerase chain reaction (qRT-PCR). These findings highlight the potential of electrochemical biosensors for the detection of pathogens and other biological entities, marking a significant advancement in this field.

A Plasmonic Nanoledge Array Sensor for Selective Detection of Cardiovascular Disease Biomarkers in Human Whole Blood.

Optical sensors face challenges when detecting ultralow amounts of analytes in whole blood, including signal quenching due to optical absorption and false positives due to nonspecific binding. This study introduces gold nanoscale array features termed nanoledges (NLs), which interact with incident white light to produce a transmitted surface plasmon resonance (tSPR) signal. This extraordinary optical transmission (EOT) spectrum occurs in the near-infrared (NIR) region, thereby minimizing signal quenching caused by visible-light absorption from blood proteins and pigments. To develop a sensitive, selective, and label-free optical biosensor for detecting various levels of cardiac troponin I (cTnI) in very small volumes of whole blood samples, DNA aptamers are tethered to the NL surface, specifically binding to the cTnI biomarker. This biological binding activity alters the refractive index at the NL surface, causing a peak shift in the EOT spectrum and enabling quantification of cTnI levels. The NL array chip demonstrated high sensitivity for cTnI detection in buffer, human serum (HS), and human whole blood (HB), with detection limits of 0.079, 0.084, and 0.097 ng/mL, respectively. Control measurements using blank target mediums and those containing up to 125 ng/mL of other proteins, such as myoglobin, creatine kinase, and heparin, showed minimal interference and high specificity. The NL plasmonic array's performance in biosensing underscores its promise for clinical analysis and its potential development as a point-of-care platform for early cardiovascular disease (CVD) diagnostics.

BaTiO3 boosted silver-based SPR sensor for efficient urine-glucose detection in pre-diabetic and early-diabetic stages

The current work studies the impact of BaTiO3 along with the various monosulfide on the sensing performance of a silver-coated surface plasmonic resonance sensor (SPR) for the noninvasive detection of glucose via urine samples. The considered monosulfides are GeS, ZnS, CdS, and CuS. After the optimization of the BaTiO3 thickness to 13 nm over the silver based SPR sensor, all above mentioned monosulfides are investigated over the BaTiO3 (BTO) layer individually. It is shown that GeS shows better performance compared to others. Maximum obtained sensitivity for the optimized structure (Prism (BK7)/ Ag (50 nm)/BaTiO3 (13 nm)/GeS (01 Layer)/Urine sample) is 527 °/RIU (the highest ever reported to date) for urine sample refractive indices range 1.335, 1.336, 1.337, 1.338, and 1.341 for corresponding glucose concentration of 0 g/dl (non-diabetic), 0.625 g/dl (pre-diabetic), 1.25 g/dl (early diabetic), 2.5 g/dl (diabetic), and 5 g/dl (high-diabetic), respectively. The investigation produced a thorough picture of the distribution of electric fields for distinct monosulfide layers. Other investigated sensing performance parameters such as detection accuracy (DA), quality factor (QF), limit of detection (LOD) are also numerically calculated and are 0.227 deg−1, 97 RIU−1 and 1.25e-5 respectively. The contrast of the suggested structure to similar relevant published work demonstrates its ability to be used as an efficient label-free biosensor.