Search Results (90)

Two-dimensional nanomaterials (2DNMs) exhibit significant potential for the development of functional and specifically targeted biosensors, owing to their unique planar nanosheet structures and distinct physical and chemical properties. Biomodification and biomimetic synthesis offer green and mild approaches for the fabrication of multifunctional nanohybrids with enhanced catalytic, fluorescent, electronic, and optical properties, thereby expanding their utility in constructing high-performance biosensors. In this review, we present recent advances in the synthesis of 2DNM-based nanohybrids via both biomodification and biomimetic strategies for biosensor applications. We discuss covalent and non-covalent biomodification methods involving various biomolecules, including peptides, proteins, DNA/RNA, enzymes, biopolymers, and bioactive polysaccharides. The engineering of biomolecule–nanomaterial interfaces for the creation of biomodified 2DNM-based nanohybrids is also explored. Furthermore, we summarize the biomimetic synthesis of 2DNM-based bio–nanohybrids through pathways such as bio-templating, biomolecule-directed self-assembly, biomineralization, and biomimetic functional integration. The potential applications of these nanohybrids in diverse biosensing platforms—including colorimetric, surface plasmon resonance, electrochemical, fluorescence, photoelectrochemical, and integrated multimodal biosensors—are introduced and discussed. Finally, we analyze the opportunities and challenges associated with this rapidly developing field. We believe this comprehensive review will provide valuable insights into the biofunctionalization of 2DNMs and guide the rational design of advanced biosensors for diagnostic applications. Full article

In low-resource and point-of-care settings, traditional PCR often faces challenges of poor sample preparation, adverse environmental conditions, and long assay times. We have previously described a laboratory-based instrument to achieve “adaptive” PCR, a PCR thermocycling control system that replaces preset cycling times and temperatures with the optical monitoring of added L-DNA stereoisomers matching the sequences of the reaction primers and target. These L-DNA biosensors directly monitor DNA hybridization, compensating for ambient environmental conditions and poor sample preparation. This report describes instrument simplifications and a comparative evaluation of both direct photothermal and plasmonic laser heating to reduce the assay time to 15 min. Instrument performance was assessed using a split sample design to compare reaction performances of 1370 and 808 nm adaptive PCR heating modalities to a standard PCR instrument. Both the novel 1370 nm direct heating and the 808 nm plasmonic method achieved target amplification similar to the traditional PCR system within 15 min. However, a major disadvantage of 808 nm heating was nanorod optical interference that reduced the fluorescence signal from PCR probes and optical cycling components. Further characterization of the 1370 nm direct heating method found comparable limits of detection of 10⁰ copies/µL and reaction efficiencies of approximately 2 for both the 1370 nm system and the traditional PCR instrument. These results suggest that a field-deployable PCR instrument design incorporating both adaptive optical control and 1370 nm laser heating can achieve 15 min sample assay times without sacrificing analytical sensitivity. Full article

This study presents a numerical investigation of surface plasmon resonance (SPR) biosensors incorporating silicon nitride (Si₃N₄) and molybdenum disulfide (MoS₂) for HIV DNA hybridization detection. By optimizing the thickness of Ag and Si₃N₄ and the number of MoS₂ layers, two configurations, Sys₂ (Ag-Si₃N₄) and Sys₃ (Ag-Si₃N₄-MoS₂), were selected for comparative analysis. Performance metrics, including the resonance angle shift, sensitivity, detection accuracy, and quality factor, demonstrated that Sys₂ achieved the highest sensitivity of 210.9°/RIU and an enhanced figure of merit (86.98 RIU⁻¹), surpassing state-of-the-art SPR sensors. Although Sys₃ exhibited a lower sensitivity of 158.1°/RIU due to MoS₂-induced optical losses, it provided a lower limit of detection, suggesting a trade-off between sensitivity and spectral broadening. Compared to previous SPR biosensors, the proposed configurations achieve superior sensitivity while maintaining stability and selectivity, positioning them as promising candidates for next-generation nucleic acid detection platforms. Full article

Biosensing shows promise in detecting cancer, renal disease, and other illnesses. Depending on their transducing processes, varieties of biosensors can be divided into electrochemical, optical, piezoelectric, and thermal biosensors. Advancements in material production techniques, enzyme/protein designing, and immobilization/conjugation approaches can yield novel nanoparticles with further developed functionality. Research in cutting-edge biosensing with multifunctional nanomaterials, and the advancement of practical biochip plans utilizing nano-based sensing material, are of current interest. The miniaturization of electronic devices has enabled the growth of ultracompact, compassionate, rapid, and low-cost sensing technologies. Some sensors can recognize analytes at the molecule, particle, and single biological cell levels. Nanomaterial-based sensors, which can be used for biosensing quickly and precisely, can replace toxic materials in real-time diagnostics. Many metal-based NPs and nanocomposites are favorable for biosensing. Through direct and indirect labeling, metal-oxide NPs are extensively employed in detecting metabolic disorders, such as cancer, diabetes, and kidney-disease biomarkers based on electrochemical, optical, and magnetic readouts. The present review focused on recent developments across multiple biosensing modalities using metal/metal-oxide-based NPs; in particular, we highlighted the specific advancements of biosensing of key nanomaterials like ZnO, CeO₂, and TiO₂ and their applications in disease diagnostics and environmental monitoring. For example, ZnO-based biosensors recognize uric acid, glucose, cholesterol, dopamine, and DNA; TiO₂ is utilized for SARS-CoV-19; and CeO₂ for glucose detection. Full article

Food safety is a pressing global concern due to the risks posed by contaminants such as pesticide residues, heavy metals, allergens, mycotoxins, and pathogenic microorganisms. While accurate, traditional detection methods like ELISA, HPLC, and mass spectrometry are often time-consuming and resource-intensive, highlighting the need for innovative alternatives. Biosensors based on biological recognition elements such as enzymes, antibodies, and aptamers, offer fast, sensitive, and cost-effective solutions. Using transduction mechanisms like electrochemical, optical, piezoelectric, and thermal systems, biosensors provide versatile tools for detecting contaminants. Advances in DNAzyme- and aptamer-based technologies enable the precise detection of heavy metals, while enzyme- and protein-based biosensors monitor metal-induced changes in biological activity. Innovations like microbial biosensors and DNA-modified electrodes enhance detection accuracy. Biosensors are also highly effective in identifying pesticide residues, allergens, mycotoxins, and pathogens through immunological, enzymatic, and nucleic acid-based techniques. The integration of nanomaterials and bioelectronics has significantly improved the sensitivity and performance of biosensors. By facilitating real-time, on-site monitoring, these devices address the limitations of conventional methods to ensure food quality and regulatory compliance. This review highlights the transformative role of biosensors and how biosensors are improved by emerging technologies in food contamination detection, emphasizing their potential to mitigate public health risks and enhance food safety throughout the supply chain. Full article

Recently, gold nanoclusters (AuNCs) have been widely used in biological applications due to their ultrasmall size, ranging within a few nanometers; large specific surface area; easy functionalization; unique fluorescence properties; and excellent conductivity. However, because they are unstable in solution, AuNCs require stabilization by using ligands such as dendrimers, peptides, DNA, and proteins. As a result, the properties of AuNCs and their formation are determined by the ligand, so the selection of the ligand is important. Of the many ligands implemented, enzyme-stabilized gold nanoclusters (enzyme–AuNCs) have attracted increasing attention for biosensor applications because of the excellent optical/electrochemical properties of AuNCs and the highly target-specific reactions of enzymes. In this review, we explore how enzyme–AuNCs are prepared, their properties, and the various types of enzyme–AuNC-based biosensors that use optical and electrochemical detection techniques. Finally, we discuss the current challenges and prospects of enzyme–AuNCs in biosensing applications. We expect this review to provide interdisciplinary knowledge about the application of enzyme–AuNC-based materials within the biomedical and environmental fields. Full article

Over the past few years, significant progress has been made in DNA origami technology due to the unrivaled self-assembly properties of DNA molecules. As a highly programmable, addressable, and biocompatible nanomaterial, DNA origami has found widespread applications in biomedicine, such as cell scaffold construction, antimicrobial drug delivery, and supramolecular enzyme assembly. To expand the scope of DNA origami application scenarios, researchers have developed DNA origami structures capable of actively identifying and quantitatively reporting targets. Optical DNA origami biosensors are promising due to their fast-to-use, sensitive, and easy implementation. However, the conversion of DNA origami to optical biosensors is still in its infancy stage, and related strategies have not been systematically summarized, increasing the difficulty of guiding subsequent researchers. Therefore, this review focuses on the universal strategies that endow DNA origami with dynamic responsiveness from both de novo design and current DNA origami modification. Various applications of DNA origami biosensors are also discussed. Additionally, we highlight the advantages of DNA origami biosensors, which offer a single-molecule resolution and high signal-to-noise ratio as an alternative to traditional analytical techniques. We believe that over the next decade, researchers will continue to transform DNA origami into optical biosensors and explore their infinite possible uses. Full article

Biosensors operating in the terahertz (THz) region are gaining substantial interest in biomedical analysis due to their significant potential for high-sensitivity trace-amount solution detection. However, progress in compact, high-sensitivity chips and methods for simple, rapid and trace-level measurements is limited by the spatial resolution of THz waves and their strong absorption in polar solvents. In this work, a compact nonlinear optical crystal (NLOC)-based reflective THz biosensor with a few arrays of asymmetrical meta-atoms was developed. A near-field point THz source was locally generated at a femtosecond-laser-irradiation spot via optical rectification, exciting only the single central meta-atom, thereby inducing Fano resonance. The reflective resonance response demonstrated dependence on several aspects, including structure asymmetricity, geometrical size, excitation point position, thickness and array-period arrangement. DNA samples were examined using 1 μL applied to an effective sensing area of 0.234 mm² (484 μm × 484 μm) for performance evaluation. The developed Fano resonance sensor exhibited nearly double sensitivity compared to that of symmetrical sensors and one-gap split ring resonators. Thus, this study advances liquid-based sensing by enabling easy, rapid and trace-level measurements while also driving the development of compact and highly sensitive THz sensors for biological samples. Full article

Developments in science and technology lead to an increasing use of scientific evidence in litigation. Interdisciplinary research can improve current procedures and introduce new ones for the disclosure and examination of evidence. The dactyloscopic trace is used for personal identification by matching minutiae (the minimum required may vary by country) or for extracting DNA material from the trace under investigation. The research presented in this article aims to propose the merging of two currently used personal identification methods, DNA analysis and dactyloscopic trace analysis, which are currently treated as separate forensic traces found at a crime scene. Namely, the forensic trace to be analyzed is the dactyloscopic trace containing DNA, and both sources of information needed for identification are examined as one. Promega’s Diamond™ Nucleic Acid Dye, presented as a safe alternative to ethidium bromide, works by binding to single- and double-stranded DNA and is used to visualize the separation of material in a gel and to detect DNA in forensic samples. Spectroscopic studies as absorption and emission spectra and fluorescence microscopy observations presented in our research confirm that Diamond™ Nucleic Acid Dye can also be used to visualize fingerprints on non-absorbent surfaces and that combining the two methods into one can significantly increase the evidential value and contribute to the design of an innovative fast-acting optical biosensor. Full article

Blood is a common biological fluid in forensic investigations, offering significant evidential value. Currently employed presumptive blood tests often lack specificity and are sample destructive, which can compromise downstream analysis. Within this study, the development of an optical biosensor for detecting human red blood cells (RBCs) has been explored to address such limitations. Aptamer-based biosensors, termed aptasensors, offer a promising alternative due to their high specificity and affinity for target analytes. Aptamers are short, single-stranded DNA or RNA sequences that form stable three-dimensional structures, allowing them to bind to specific targets selectively. A nanoflare design has been employed within this work, consisting of a quenching gold nanoparticle (AuNP), DNA aptamer sequences, and complementary fluorophore-labelled flares operating through a fluorescence resonance energy transfer (FRET) mechanism. In the presence of RBCs, the aptamer–flare complex is disrupted, restoring fluorescence and indicating the presence of blood. Two aptamers, N1 and BB1, with a demonstrated binding affinity to RBCs, were selected for inclusion within the nanoflare. This study aimed to optimise three features of the design: aptamer conjugation to AuNPs, aptamer hybridisation to complementary flares, and flare displacement in the presence of RBCs. Fluorescence restoration was achieved with both the N1 and BB1 nanoflares, demonstrating the potential for a functional biosensor to be utilised within the forensic workflow. It is hoped that introducing such an aptasensor could enhance the forensic workflow. This aptasensor could replace current tests with a specific and sensitive reagent that can be used for real-time detection, improving the standard of forensic blood analysis. Full article

Despite the existing effective treatment methods, tuberculosis (TB) is the second most deadly infectious disease, its carriers in the latent and active phases accounting for more than 20% of the world population. An effective method for controlling TB and reducing TB mortality is regular population screening aimed at diagnosing the latent form of TB and taking preventive and curative measures. Numerous methods allow diagnosing TB by directly detecting Mycobacterium tuberculosis (M.tb) biomarkers, including M.tb DNA, proteins, and specific metabolites or antibodies produced by the host immune system in response to M.tb. PCR, ELISA, immunofluorescence and immunochemical analyses, flow cytometry, and other methods allow the detection of M.tb biomarkers or the host immune response to M.tb by recording the optical signal from fluorescent or colorimetric dyes that are components of the diagnostic systems. Current research in biosensors is aimed at increasing the sensitivity of detection, a promising approach being the use of fluorescent quantum dots as brighter and more photostable optical tags. Here, we review current methods for the detection of M.tb biomarkers using quantum dot-based nanosensors and summarize data on the M.tb biomarkers whose detection can be made considerably more sensitive by using these sensors. Full article

Brevetoxins (PbTxs) are very potent marine neurotoxins that can cause an illness clinically described as neurologic shellfish poisoning (NSP). These toxins are cyclic polyether in chemistry and have increased their geographical distribution in the past 2 decades. However, the ethical problems as well as technical difficulties associated with currently employed analysis methods for marine toxins have spurred the quest for suitable alternatives to be applied in a regulatory monitoring regime. In this work, we reported the first instance of concurrent aptamer selection of Brevetoxin-1 (PbTx-1) and Brevetoxin-2 (PbTx-2) and constructed a biolayer interferometry (BLI) biosensor utilizing PbTx-1 aptamer as a specific recognition element. Through an in vitro selection process, we have, for the first time, successfully selected DNA aptamers with high affinity and specificity to PbTx-1 and PbTx-2 from a vast pool of random sequences. Among the selected aptamers, aptamer A5 exhibited the strongest binding affinity to PbTx-1, with an equilibrium dissociation constant (K_D) of 2.56 μM. Subsequently, we optimized aptamer A5 by truncation to obtain the core sequence (A5-S3). Further refinement was achieved through mutations based on the predictions of a QGRS mapper, resulting in aptamer A5-S3G, which showed a significant increase in the K_D value by approximately 100-fold. Utilizing aptamer A5-S3G, we fabricated a label-free, real-time optical BLI aptasensor for the detection of PbTx-1. This aptasensor displayed a broad detection range from 100 nM to 4000 nM PbTx-1, with a linear range between 100 nM and 2000 nM, and a limit of detection (LOD) as low as 4.5 nM. Importantly, the aptasensor showed no cross-reactivity to PbTx-2 or other marine toxins, indicating a high level of specificity for PbTx-1. Moreover, the aptasensor exhibited excellent reproducibility and stability when applied for the detection of PbTx-1 in spiked shellfish samples. We strongly believe that this innovative aptasensor offers a promising alternative to traditional immunological methods for the specific and reliable detection of PbTx-1. Full article

DNA is fundamental for storing and transmitting genetic information. Analyzing DNA or RNA base sequences enables the identification of genetic disorders, monitoring gene expression, and detecting pathogens. Traditional detection techniques like polymerase chain reaction (PCR) and next-generation sequencing (NGS) have limitations, including complexity, high cost, and the need for advanced computational skills. Therefore, there is a significant demand for enzyme-free and amplification-free strategies for rapid, low-cost, and sensitive DNA detection. DNA biosensors, especially those utilizing plasmonic nanomaterials, offer a promising solution. This study introduces a novel DNA-functionalized waveguide-enhanced nanoplasmonic optofluidic biosensor using a nanogold-linked sorbent assay for enzyme-free and amplification-free DNA detection. Integrating plasmonic gold nanoparticles (AuNPs) with a glass planar waveguide (WG) and a microfluidic channel, fabricated through cost-effective, vacuum-free methods, the biosensor achieves specific detection of complementary target DNA sequences. Utilizing a sandwich architecture, AuNPs labeled with detection DNA probes enhance sensitivity by altering evanescent wave distribution and inducing plasmon resonance modes. The biosensor demonstrated exceptional performance in DNA detection, achieving a limit of detection (LOD) of 33.1 fg/mL (4.36 fM) with a rapid response time of approximately 8 min. This ultrasensitive, rapid, and cost-effective biosensor exhibits minimal background nonspecific adsorption, making it highly suitable for clinical applications and early disease diagnosis. The innovative design and fabrication processes offer significant advantages for mass production, presenting a viable tool for precise disease diagnostics and improved clinical outcomes. Full article

Biosensors are used for the specific and sensitive detection of biomolecules. In conventional approaches, the suspected target molecules are bound to selected capture molecules and successful binding is indicated by additional labelling to enable optical readout. This labelling requires additional processing steps tailored to the application. While numerous label-free interaction assays exist, they often compromise on detection characteristics. In this context, we introduce a novel diffractometric biosensor, comprising a diffractive biosensor chip and an associated optical reader assembly. This innovative system can capture an entire assay, detecting various types of molecules in a label-free manner and present the results within in a single, comprehensive image. The applicability of the biosensor is assessed for the detection of viral DNA as well as proteins directly in human plasma, investigating different antigens. In our experiments, we achieve a detection limit of 4.2 pg/mm², which is comparable to other label-free optical biosensors. The simplicity and robustness of the method make it a compelling option for advancing biosensing technologies. This work contributes to the development of an imaging diffractometric biosensor with the potential for multiple applications in molecular interaction analysis. Full article

Biosensors in the Terahertz (THz) region are attracting significant attention in the biomedical and chemical analysis fields owing to their potential for ultra-trace sensing of various solutions with high sensitivity. However, the development of compact, highly sensitive chips and methods for easy, rapid, and trace-amount measurements have been significantly hindered by the limited spatial resolution of THz waves and their strong absorption by water. In this study, we developed a nonlinear optical crystal (NLOC)-based compact THz sensor chip, and a near-field point THz source with a diameter of ~ϕ20 μm was locally generated via optical rectification. Here, only the single central meta-atom was excited. The reflective resonance responses highly depend on the array number and period of the meta-atom structures. The sensing performance was examined with several liquid biological samples, such as mineral water, DNA, and human blood. 1 μL of samples was directly dropped onto the meta-surface with an effective sensing area of 0.32 mm² (564 μm × 564 μm). Obvious resonance frequency shifts were clearly observed. This research holds significance in advancing liquid bio-sample sensing methodologies by facilitating easy, rapid, and trace-amount measurements and promoting the development of compact and highly sensitive THz sensors tailored for liquid biological samples. Full article