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Accurate and rapid quantification of cytokines in biofluids is crucial for early disease diagnosis, management, and prevention. However, it still remains challenging for existing sensors due to the broad dynamic range of cytokines and high interference from sample matrices. To overcome these challenges, electrochemical (EC) and field‐effect transistor (FET) dual‐mode biosensing is integrated on an extended‐gate carbon nanotube field‐effect transistor. This biosensor chip effectively eliminates direct contact between the device and the solution and employs independent signal readouts based on two distinct response mechanisms, thereby circumventing the limitations associated with conventional transistor biosensors. Selective detection of cytokine (e.g., Interferon‐γ, IFN‐γ) is achieved by the FET sensing mode (0.1 to 4000 pg mL−1, with a limit of detection of 24.1 fg mL−1) and the EC sensing mode (0.4–2000 ng mL−1) at different concentration range. The feasibility of real sample analysis using the EC‐FET dual‐mode biosensor is confirmed by detecting salivary levels of IFN‐γ. The combination of EC and FET sensing modes not only provides high sensitivity and a wide response range (seven orders of magnitude) to accommodate various biological samples but also improves the reliability of detection results, which shows promising applications in biological analysis and early disease diagnosis. [ABSTRACT FROM AUTHOR]

We demonstrated a nonenzymatic electrochemical sensor based upon vanadium-doped nickel oxide composite with graphitic carbon nitride. The g-C 3 N 4 was prepared by annealing Urea at 550 °C for 3 h in a muffle furnace. The nanocomposite was synthesized using a microwave-assisted method, followed by thermal annealing at different temperatures. The successful formation of V–NiO/g-C 3 N 4 was confirmed by X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy. SEM images show the layered sheets with porous structure, which depends on annealing temperature; as we increase the temperature, the porosity increases. Afterwards, the electrochemical sensing properties were verified by CV, LSV, DPV, and amperometric studies in 0.2 M KOH in the presence of Ascorbic acid and Dopamine. The experimental results show that our prepared sample has excellent electrochemical biosensing abilities towards AA and DA with LOD 1.16 μM and 0.16 μM, respectively. It also offers good selectivity, exceptional reproducibility, and long-term stability owing to the combined effect of NiO and g-C 3 N 4. Finally, the electrochemical sensing of H 2 O 2 was detected in the same environment by conducting CV and amperometric studies. Our modified electrode has proven its noble ability to sense H 2 O 2 with excellent repeatability, stability and low LOD 0.2 μM with a wide linear working range (0.5 mM–4 mM). It has the potential to be used for multi-molecule selection biosensing with excellent selectivity and sensitivity. [Display omitted] [ABSTRACT FROM AUTHOR]

This study presents a cancer diagnostics method through the development of a graphitic carbon nitride (g-C3N4)-based electrochemical sensor for detecting circulating tumor cells (CTCs) in blood. Utilizing the unique properties of g-C3N4 nanosheets combined with gold nanoparticles functionalized with DNA aptamers, the sensor exhibits remarkable sensitivity and selectivity in CTC detection. The aptamers specifically target cell surface biomarkers, enabling the precise capture and quantification of CTCs. The sensor's detection limit is an impressive 5 cells/mL, with a broad detection range from 10 to 105 cells/mL. This high-performance sensing platform not only achieves rapid and accurate quantification of CTCs but also demonstrates robustness against interference from other cell types, making it highly suitable for clinical applications. The optimized conditions for aptamer-functionalized nanoparticle concentration and incubation time ensure the sensor's efficacy, as validated in spiked blood samples. This work provides a practical and efficient approach for non-invasive cancer diagnostics, offering significant improvements over existing methods in terms of simplicity, sensitivity, and specificity for early detection and monitoring of cancer progression.

This study presents a cancer diagnostics method through the development of a graphitic carbon nitride (g-C 3 N 4)-based electrochemical sensor for detecting circulating tumor cells (CTCs) in blood. Utilizing the unique properties of g-C 3 N 4 nanosheets combined with gold nanoparticles functionalized with DNA aptamers, the sensor exhibits remarkable sensitivity and selectivity in CTC detection. The aptamers specifically target cell surface biomarkers, enabling the precise capture and quantification of CTCs. The sensor's detection limit is an impressive 5 cells/mL, with a broad detection range from 10 to 105 cells/mL. This high-performance sensing platform not only achieves rapid and accurate quantification of CTCs but also demonstrates robustness against interference from other cell types, making it highly suitable for clinical applications. The optimized conditions for aptamer-functionalized nanoparticle concentration and incubation time ensure the sensor's efficacy, as validated in spiked blood samples. This work provides a practical and efficient approach for non-invasive cancer diagnostics, offering significant improvements over existing methods in terms of simplicity, sensitivity, and specificity for early detection and monitoring of cancer progression. [ABSTRACT FROM AUTHOR]

In this article, controlled and restricted growth of cobalt nanoparticles embedded in ordered mesoporous carbon @ carbon nanotubes was designed and synthesized. SBA‐15 was used as template, the polydopamine (PDA) was used as bridging agent, the carbon and nitrogen source and cobalt phthalocyanine was used as cobalt source. In the process of high temperature calcination, ordered mesoporous carbons was carbonized, transition metal ions were reduced to transition metal nanoparticles, and carbon nanotubes were catalyzed growth by cobalt at the same time. Combined high surface area and stability of ordered mesoporous carbons, high electrocatalytic activity of transition metal nanoparticles and high proton transport performance of carbon nanotubes, our preparaed Co NPs @NOMC@CNTs showed excellent electrocatalytic performance for metronidazole. In this paper, cobalt nanoparticles were embedded into the ordered mesoporous carbons, which can greatly enhance the active site inside the electrocatalyst, and limit the growth of nanoparticles, and achieve efficient electrocatalytic performance. This provides new ideas and methods for the preparation of new materials embedded with metal nanoparticles. The preparation process of the composite material is simple, green and economical, the synthesis method is novel, the preparation material is efficient, the preparation cost is low, and it has a broad application prospect in the industrialization field of economical and green electrocatalyst. [ABSTRACT FROM AUTHOR]

Point‐of‐care technologies need particularly stringent requirements, including portability, rapidity, affordability, and ease of use, enabling healthcare practitioners to perform reliable analyses in decentralized settings. Such diagnostic tests are usually based on bioassays that allow for the detection of clinically relevant biomarkers, namely proteins, antibodies and nucleic acids. In the context of electrochemical biosensors, the implementation of magnetic beads offers unique advantages stemming from their high surface‐to‐volume ratio, easy manipulation through magnetic fields and versatility in surface chemistries for bio‐conjugation. The present concept article highlights the advantages achieved through the implementation of magnetic beads in electrochemical binding assays, immunosensors and genosensors. These methods mostly exploit magnetic beads for immobilization purposes, allowing for the assembly of bio‐complexes in liquid suspensions under precise temperature and shaking control, as well as simplifying the manipulation steps to enable untrained personnel to perform analyses. In addition, magnetic beads can also take part in the detection mechanism, leading to innovative sensing strategies with great potential for point‐of‐care diagnostic applications. [ABSTRACT FROM AUTHOR]

In the era that we seek personalization in material things, it is becoming increasingly clear that the individualized management of medicine and nutrition plays a key role in life expectancy and quality of life, allowing participation to some extent in our welfare and the use of societal resources in a rationale and equitable way. The implementation of precision medicine and nutrition are highly complex challenges which depend on the development of new technologies able to meet important requirements in terms of cost, simplicity, and versatility, and to determine both individually and simultaneously, almost in real time and with the required sensitivity and reliability, molecular markers of different omics levels in biofluids extracted, secreted (either naturally or stimulated), or circulating in the body. Relying on representative and pioneering examples, this review article critically discusses recent advances driving the position of electrochemical bioplatforms as one of the winning horses for the implementation of suitable tools for advanced diagnostics, therapy, and precision nutrition. In addition to a critical overview of the state of the art, including groundbreaking applications and challenges ahead, the article concludes with a personal vision of the imminent roadmap. [ABSTRACT FROM AUTHOR]

The continuous, real-time measurement of specific molecules in situ in the body would greatly improve our ability to understand, diagnose, and treat disease. The vast majority of continuous molecular sensing technologies, however, either (1) rely on the chemical or enzymatic reactivity of their targets, sharply limiting their scope, or (2) have never been shown (and likely will never be shown) to operate in the complex environments found in vivo. Against this background, here we review electrochemical aptamer-based (EAB) sensors, an electrochemical approach to real-time molecular monitoring that has now seen 15 years of academic development. The strengths of the EAB platform are significant: to date it is the only molecular measurement technology that (1) functions independently of the chemical reactivity of its targets, and is thus general, and (2) supports in vivo measurements. Specifically, using EAB sensors we, and others, have already reported the real-time, seconds-resolved measurements of multiple, unrelated drugs and metabolites in situ in the veins and tissues of live animals. Against these strengths, we detail the platform's remaining weaknesses, which include still limited measurement duration (hours, rather than the more desirable days) and the difficulty in obtaining sufficiently high performance aptamers against new targets, before then detailing promising approaches overcoming these hurdles. Finally, we close by exploring the opportunities we believe this potentially revolutionary technology (as well as a few, possibly competing, technologies) will create for both researchers and clinicians.

Gastric cancer (GC) is one of the considered enormously important cancer types in the world. A large number of mortality rates have revealed that there is a massive shortage in the prognosis and treatment of GC because the majority of GC cases are identified at an advanced stage. In this regard, the rapid platform for non-invasive detection of GC cells through the analysis of GC biomarkers in the first stages with high sensitivity is essential for the success in the treatment of GC. In recent years, different types of electrochemical immunosensors as efficient sensing devices with benefits including accuracy, reproducibility and low cost have played an extremely significant role in the monitoring of GC. One of the significant issues in the development of electrochemical immunosensors is to increase the system's sensitivity. A variety of nanomaterials based on carbon-based, silica-based and metallic-based nanomaterials have been used as sensing platforms on the different types of electrochemical electrodes for improving the properties of biodevices. This review highlighted the new progress and technical breakthroughs comprising electrochemical immunosensor for the determination of GC biomarkers including CA19-9, CA72-4, CA125 and CEA. In diverse matrices and proved how nanoprobes could enhance the performance of electrochemical immunsensing approaches. [ABSTRACT FROM AUTHOR]

A major societal challenge is the development of the necessary tools for early diagnosis of diseases such as cancer and sepsis. Consequently, there is a concerted push to develop low-cost and non-invasive methods of analysis with high sensitivity and selectivity. A notable trend is the development of highly sensitive methods that are not only amenable for point-of-care (POC) testing, but also for wearable devices allowing continuous monitoring of biomarkers. In this context, a non-invasive test for the detection of a promising biomarker, the protein Interleukin-6 (IL-6), could represent a significant advance in the clinical management of cancer, in monitoring the chemotherapy response, or for prompt diagnosis of sepsis. This work reports a capacitive electrochemical impedance spectroscopy sensing platform tailored towards POC detection and treatment monitoring in human serum. The specific recognition of IL-6 was achieved employing gold surfaces modified with an anti-IL6 nanobody (anti-IL-6 VHH) or a specific IL-6 aptamer. In the first system, the anti-IL-6 VHH was covalently attached to the gold surface using a binary self-assembled-monolayer (SAM) of 6-mercapto-1-hexanol (MCH) and 11-mercaptoundecanoic acid. In the second system, the aptamer was chemisorbed onto the surface in a mixed SAM layer with MCH. The analytical performance for each label-free sensor was evaluated in buffer and 10% human serum samples and then compared. The results of this work were generated using a low-cost, thin film eight-channel gold sensor array produced on a flexible substrate providing useful information on the future design of POC and wearable impedance biomarker detection platforms. [ABSTRACT FROM AUTHOR]

Gold-platinum alloy nanoparticles (AuPtNP) were electrochemically deposited on the surface of indium-tin-oxide (ITO) modified with (3-aminopropyl)triethoxysilane (APTES), after optimizing deposition conditions for the electroplating solution and number of deposition cycles. Different part ratios of Au/Pt used were 4/0, 3/1, 2/2, 1/3 and 0/4 (AuNP, Au3Pt1, Au2Pt2, Au1Pt3 and PtNP, respectively) in preparation of 1 mM solutions. FE-SEM, EDAX and XRD surface characterization techniques were used to confirm the presence of deposited AuPt alloy nanoparticles on the modified ITO surface. Electrochemical methods (CV, DPV and EIS) were used to investigate the electrochemical properties of prepared electrodes in the presence of ferri/ferrocyanide redox couple, which indicated the following increasing order of electrocatalytic peak current: Au

Chronic wounds arising from accidents, surgeries, or diseases impose a significant clinical and economic burden, underscoring the need for effective solutions to prevent severe complications. Recent advancements in materials science and electrochemical technology have facilitated the development of conformable electrochemical platforms for detection and management, incorporating monitoring, diagnosis, and treatment. Nevertheless, current wound detection and therapy systems face challenges related to the stability and specificity of sensor monitoring, as well as the need for on-site and comprehensive evaluation criteria to offer timely treatment guidance and follow-up care. This review provides a comprehensive overview of the closed-loop management system, emphasizing wound biomarker detection, wound assessment, and on-demand treatment, ultimately culminating in an integrated wound management approach by conformable electrochemical devices. Additionally, we explore the challenges, opportunities, and future prospects of soft and stretchable electrochemical biosensors, with the aim of enhancing the efficiency and timeliness of wound management.

Epigenetic modifications are closely related to diseases and physiological health, mainly including DNA methylation, RNA methylation, histone acetylation, and noncoding RNA. Recently, a large amount of research has been conducted on the detection of epigenetic modifications. Electrochemical biosensors, with their low cost, high sensitivity, high compatibility, and simple operation, have been widely used in the detection of epigenetic biomarkers. This review discusses the detection of epigenetic biomarkers using different electrochemical sensing methods. Here we discuss various aspects, including free labels, signal labeling, signal amplification, nano-based electrodes, and the combined use of other methods. By summarizing the existing electrochemical detection methods for epigenetic modifications, this review also proposes future development trends and challenges for electrochemical biosensors in this field. [ABSTRACT FROM AUTHOR]

The purpose of this study was to achieve a specific unlocking of the butterfly effect: nanointerface-based electrochemical biosensing of adenosine triphosphate (ATP) and alkaline phosphatase (ALP). Based on the Faraday-cage concept reported first by our group, we built a new outer Helmholtz plane (OHP)-based electrochemical biosensor by using an unique nanocomposite involving three-dimensional graphene-Au nanoparticles (3D-GO-AuNPs), tetrahedral DNA nanostructures (TDNs), and separated ATP aptamers, in which methylene blue (MB) was employed as the electrochemical signal output. In this process, the prepared nanocomposites were attached favorably onto the TDN substrate electrode surface due to the interaction of ATP and its aptamer, creating a better OHP of the electrode owing to its large enough specific surface area; then a detection limit of 0.25 pM was calculated by 3δ/slope. Whereas, the hydrolysis for ATP of ALP can hinder this binding process, therefore, the biosensor could be indirectly applied for ALP analysis with a detection limit of 0.21 mU/L (3δ/slope). Since some small changes of the two targets will set off a whole series of changes in system, the OHP-extended biosensor provides a superior electrochemical platform for complex biological processes with causal relationships in clinical diagnosis and drug development, similar to the butterfly effect. [ABSTRACT FROM AUTHOR]

Mycotoxins are naturally occurring toxic secondary metabolites produced by fungi in cereals and foodstuffs during the stages of cultivation and storage. Electrochemical biosensing has emerged as a rapid, efficient, and economical approach for the detection and quantification of mycotoxins in different sample media. An electrochemical biosensor consists of two main units, a recognition receptor and a signal transducer. Natural or artificial antibodies, aptamers, molecularly imprinted polymers (MIP), peptides, and DNAzymes have been extensively employed as selective recognition receptors for the electrochemical biosensing of mycotoxins. This article affords a detailed discussion of the recent advances and future prospects of various types of recognition receptors exploited in the electrochemical biosensing of mycotoxins. [ABSTRACT FROM AUTHOR]

This work presents an in vivo stem-mounted sensor for Nicotiana tabacum plants and an in situ cell suspension sensor for Solanum lycopersicum cells. Stem-mounted sensors are mechanically stable and less sensitive to plant and air movements than the previously demonstrated leaf-mounted sensors. Interdigitated-electrode-arrays with a dual working electrode configuration were used with an auxiliary electrode and an Ag/AgCl quasi-reference electrode. Signal amplification by redox cycling is demonstrated for a plant-based sensor responding to enzyme expression induced by different cues in the plants. Functional biosensing is demonstrated, first for constitutive enzyme expression and later, for heat-shock-induced enzyme expression in plants. In the cell suspension with redox cycling, positive detection of the enzyme β-glucuronidase (GUS) was observed within a few minutes after applying the substrate (pNPG, 4-Nitrophenyl β-D-glucopyranoside), following redox reactions of the product (p-nitrophenol (pNP)). It is assumed that the initial reaction is the irreversible reduction of pNP to p-hydroxylaminophenol. Next, it can be either oxidized to p-nitrosophenol or dehydrated and oxidized to aminophenol. Both last reactions are reversible and can be used for redox cycling. The dual-electrode redox-cycling electrochemical signal was an order of magnitude larger than that of conventional single-working electrode transducers. A simple model for the gain is presented, predicting that an even larger gain is possible for sub-micron electrodes. In summary, this work demonstrates, for the first time, a redox cycling-based in vivo plant sensor, where diffusion-based amplification occurs inside a tobacco plant's tissue. The technique can be applied to other plants as well as to medical and environmental monitoring systems. [ABSTRACT FROM AUTHOR]

The limitations of solvent residues, unmanageable film growth regions, and substandard performance impede the extensive utilization of metal-organic framework (MOF) films for biosensing devices. Here, we report a strategy for ion design in gas-phase synthesized flexible MOF porous film to attain universal regulation of biosensing performances. The key fabrication process involves atomic layer deposition of induced layer coupled with lithography-assisted patterning and area-selective gas-phase synthesis of MOF film within a chemical vapor deposition system. Sensing platforms are subsequently formed to achieve specific detection of H 2 O 2 , dopamine, and glucose molecules by respectively implanting Co, Fe, and Ni ions into the network structure of MOF films. Furthermore, we showcase a practical device constructed from Co ions-implanted ZIF-4 film to accomplish real-time surveillance of H 2 O 2 concentration at mouse wound. This study specifically elucidates the electronic structure and coordination mode of ion design in MOF film, and the obtained knowledge aids in tuning the electrochemical property of MOF film for advantageous sensing devices. [ABSTRACT FROM AUTHOR]

The increased water contamination caused by heavy metal ions has negative consequences for human beings. The majority of these metal ions are incredibly poisonous, nonbiodegradable, and bioaccumulative. Therefore, the detection of these hazardous heavy metal ions is crucial in the current situation. The sensing mechanism of electrochemical biosensors must be understood to increase the sensing performance, such as selectivity, sensitivity, detection limit, repeatability, and reproducibility for application scenarios. The present investigation demonstrates the preparation of l-Glutathione modified Poly (3,4-ethylenedioxythiophene): polystyrene sulfonate/carboxylated multiwall carbon nanotubes (LGSH@PEDOT:PSS/MWCNTs-COOH) network by the solution processing method. The efficacy of the LGSH@PEDOT: PSS/MWCNTs-COOH network has been investigated using GIXRD, Raman, UV-Vis, FT-IR, AFM, CV, and EIS. The detection capability of the LGSH@PEDOT: PSS/MWCNTs-COOH network as a biosensor has been investigated utilizing the DPASV technique. The presented Cd(II) biosensor exhibited a sensitivity of 10.69 μA/ppm and a detection limit of 1 ppb. Moreover, the developed biosensor exhibited good selectivity, repeatability (RSD = 1.83%), and reproducibility (RSD = 4.73%). These favorable results make LGSH@PEDOT: PSS/MWCNTs-COOH electrode as an excellent Cd(II) ions detection probe as the next generation electrochemical biosensor to detect lungs, kidney, and breast cancers.

Organic thin film transistors (OTFTs) enable rapid and label-free high-sensitivity detection of target analytes due to their low cost, large-area processing, biocompatibility, and inherent signal amplification. At the same time, the freedom of synthesis, tailorability, and functionalization of organic semiconductor materials and their ability to be combined with flexible substrates make them one of the ideal platforms for biosensing. However, OTFTs-based biosensors still face significant challenges, such as unexpected surface adsorption, disordered conformation, inhomogeneous graft density, and flexibility of probe molecules that biological sensing probes would face during immobilization. In this review, efficient immobilization strategies based on OTFTs biological sensing probes developed in the last 5 years are highlighted. First, the biosensors are classified according to their sensing interface. Second, a comprehensive discussion of the types of biological sensing probes is presented. Third, three commonly used methods for immobilizing biological sensing probes and their challenges are briefly described. Finally, the applications of OTFTs-based biosensors for liquid phase detection are summarized. This review provides a comprehensive and timely review of optimization in sensing interface engineering so that efficient immobilization of biological sensing probes with sensing interfaces will contribute to the development of high-performance OTFTs-based biosensors., (© 2024 Wiley‐VCH GmbH.)

Tuberculosis (TB) remains a leading cause of death globally, especially in underdeveloped nations. The main impediment to TB eradication is a lack of efficient diagnostic tools for disease diagnosis. In this work, label free and ultrasensitive electrochemical DNA biosensor for detecting Mycobacterium tuberculosis has been developed based on the electrodeposition of gold nanoparticles on the surface of carbon screen-printed carbon electrode (Zensors) for signal amplification. Particularly, screen-printed electrodes were modified by electrochemical deposition of Au to enhance the conductivity and facilitate the immobilization of ssDNA probes via Au-S bonds. The electrochemically modified SPEs were characterized using Scanning electron microscopy/Energy Dispersive X-Ray Analysis (SEM/EDX) and X-Ray Diffraction (XRD). Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques were used to investigate the DNA hybridization between single-stranded (ssDNA) probe and target DNA (tDNA). Under the ideal conditions, DPV exhibited a correlation coefficient R2 = 0.97, when analyzed with different tDNA concentrations. The proposed DNA biosensor exhibits a good detection range from 2 to 10 nm with a low detection limit of 1.91 nm, as well as high selectivity that, under ideal conditions, distinguishes non-complementary DNA from perfectly matched tDNA. By eliminating the need for DNA purification, this work paves the path for creating disposable biosensors capable of detecting DNA from raw sputum samples.

Epigenetic modifications are closely related to diseases and physiological health, mainly including DNA methylation, RNA methylation, histone acetylation, and noncoding RNA. Recently, a large amount of research has been conducted on the detection of epigenetic modifications. Electrochemical biosensors, with their low cost, high sensitivity, high compatibility, and simple operation, have been widely used in the detection of epigenetic biomarkers. This review discusses the detection of epigenetic biomarkers using different electrochemical sensing methods. Here we discuss various aspects, including free labels, signal labeling, signal amplification, nano-based electrodes, and the combined use of other methods. By summarizing the existing electrochemical detection methods for epigenetic modifications, this review also proposes future development trends and challenges for electrochemical biosensors in this field.

[Display omitted] Nanocellulose materials have gained growing interest in the fields of nanotechnology and materials science due to their outstanding qualities, such as tunable surface chemistry, high specific surface area, low toxicity, and ease of availability from various plant sources, animals and bacteria. These versatile materials are used in a variety of applications, e.g., drug delivery, tissue engineering, sensing and biosensing, fire retardation, catalysis, food packaging, and wastewater treatment because they are renewable, durable, biodegradable, and have unique morphological characteristics and chemical capabilities. The properties of nanocellulose are impacted by how it is extracted and functionalised. This entails the modification of cellulosic nanomaterials through the use of small molecules to induce ionic charges and create hydrophobic surfaces. Additionally, macromolecules, such as polymer grafts on the nanocellulose backbone, are employed to expand its potential applications in diverse dimensions. Moreover, the incorporation of inorganic nanoparticles is pivotal in enhancing various characteristics of nanocellulose, including thermal, mechanical, electrical, optical, and catalytic properties. These modifications collectively enhance the properties of cellulosic nanomaterials, making them valuable in sensing and biosensing applications, as well as reinforcing agents in nanocomposites. The main theme of this review is to offer comprehensive guidance for the preparation of functionalized nanocellulose materials using a diverse array of small molecules, macromolecules, and inorganic nanoparticles. Additionally, the review endeavors to evaluate the potential applications of these materials in the realms of sensing and biosensing. Furthermore, the review aims to provide a detailed overview of dual-mode biosensing platforms, highlighting the unique advantages afforded by cellulosic nanomaterials as dual-functional nanohybrids. [ABSTRACT FROM AUTHOR]

• The biosensor was assembled by Au-MoS 2 /rGO nanomaterial and DNA probe. • A low limit of quantitation and excellent specificity were achieved. • The reliability and accuracy of the biosensor were proved by droplet digital PCR. • Dynamic and on-site analysis of V. coralliilyticus eDNA in seawater was realized. • The capability of the biosensor in early warning of coral disease was evaluated. Heat stress and coral diseases are the predominant factors causing the degradation of coral reef ecosystems. Over recent years, Vibrio coralliilyticus was identified as a temperature-dependent pathogen causing tissue lysis in Pocillopora damicornis and one of the primary pathogens causing bleaching and mortality in other corals. Yet current detection techniques for V. coralliilyticus rely primarily on qPCR and ddPCR, which cannot meet the requirements for non-invasive and real-time detection. Herein, we developed an effective electrochemical biosensor modified by an Au-MoS 2 /rGO (AMG) nanocomposites and a specific capture probe to dynamically detect V. coralliilyticus environment DNA (eDNA) in aquarium experiments, with a lower limit of detection (0.28 fM) for synthetic DNA and a lower limit of quantification (9.8 fg/µL, ∼0.86 copies/µL) for genomic DNA. Its reliability and accuracy were verified by comparison with the ddPCR method (P > 0.05). Notably, coral tissue started to lyse at only 29 °C when the concentration of V. coralliilyticus increased abruptly to 880 copies/µL, indicating the biosensor could reflect the types of pathogen and health risks of corals under heat stress. Overall, the novel and reliable electrochemical biosensing technology provides an efficient strategy for the on-site monitoring and early warning of coral health in the context of global warming. [ABSTRACT FROM AUTHOR]

[Display omitted] • Performed In-depth in-silico analysis and in-vitro SELEX based validation of selected aptamers. • Fabricated aptasensors platform for the detection of SARS-CoV-2 with LOD of 0.99 and 1.1 pM (R-21 and SD-2), respectively. • Developed aptasensor exhibited a specificity of 93.8% and 92.3% (R-21 and SD-2), respectively. The COVID-19 pandemic has profoundly impacted the world, characterized by its rapid transmission and substantial death toll. In light of this, numerous rapid sensing and diagnostic technologies have emerged where aptamers have evolved as a promising alternate to antibodies for sensing and diagnostics. In this work, the Receptor Binding Domain (RBD) of SARS-CoV-2 was selected as the target for screening of aptamers using the Systematic Evolution of Ligands by Exponential Enrichment (SELEX) method and screened aptamer was named as R-21 (K D = 5.9 nM). We conducted its comparison with a previously reported aptamer for its applicability in biosensing of SARS-CoV-2. Bioinformatics and computational tools, such as GROMACS, and UCSF Chimera, were employed to analyze the secondary structure of the aptamers, aptamer-target (RBD) interactions, and their overall interaction behaviour. Subsequently, we fabricated a Screen-Printed Carbon Electrode (SPCE) based electrochemical aptasensor by coating SD-2 and R-21 over the surface of SPCE. The Limit of Detection (LOD) for SD-2 and R-21 was determined to be 1.1 and 0.99 pM, respectively, within a linear range of 1 pM to 100 nM. The fabricated aptasensor demonstrated the ability to detect heat-killed SARS-CoV-2 in 100 clinical nasopharyngeal samples (preserved in viral transport medium-VTM) with a specificity of 92.3 % and 93.8 % (with SD-2 and R-21, respectively). Therefore, this technique holds promise as a rapid diagnostic tool for the initial mass screening of SARS-CoV-2 and warrants further development. [ABSTRACT FROM AUTHOR]

Carbon-based nanozymes possessing peroxidase-like activity have attracted significant interest because of their potential to replace native peroxidases in biotechnology. Although various carbon-based nanozymes have been developed, their relatively low catalytic efficiency needs to be overcome to realize their practical utilization. Here, inspired by the elemental uniqueness of Cu and the doped elements N and S, as well as the active site structure of Cu-centered oxidoreductases, we developed a new carbon-based peroxidase-mimicking nanozyme, single-atom Cu-centered N- and S-codoped reduced graphene oxide (Cu-NS-rGO), which preserved many Cu–N 4 and Cu–N 4 S active sites and showed dramatically high peroxidase-like activity without any oxidase-like activity, yielding up to 2500-fold higher catalytic efficiency (k cat /K m) than that of pristine rGO. The high catalytic activity of Cu-NS-rGO might be attributed to the acceleration of electron transfer from Cu single atom as well as synergistic effects from both Cu–N 4 and Cu–N 4 S active sites, which was theoretically confirmed by Gibbs free energy calculations using density functional theory. The prepared Cu-NS-rGO was then used to construct an electrochemical bioassay system for detecting choline and acetylcholine by coupling with the corresponding oxidases. Using this system, both target molecules were selectively determined with high sensitivity that was sufficient to clinically determine their levels in physiological fluids. Overall, this study will facilitate the development of nanocarbon-based nanozymes and their electrochemical biosensing applications, which can be extended to the development of miniaturized devices in point-of-care testing environments. [Display omitted] [ABSTRACT FROM AUTHOR]

Sensitive and accurate analysis of specific subpopulations in circulating extracellular vesicles (EVs) can provide a wealth of information for cancer diagnosis and management. Thus, we propose herein a new electrochemical biosensing method based on a proximity labeling-assisted click conjugation strategy. The method's core design is use of antibody-guided proximity labeling to equip target EVs with a large amount of alkyne groups, so that azide-tagged silver nanoparticles can be accurately loaded onto target EV surfaces, via click conjugation, to generate significant electrochemical responses. Adopting CD44-positive EVs as the model, the electrochemical method was demonstrated by analyzing target EVs across a wide linear range (103–109 particles/mL) with acceptable sensitivity and specificity. Satisfactory utility in clinical blood samples, and versatility with human epidermal growth factor receptor-2-positive EVs as alternative targets, were also shown. This method may thus provide a novel approach to specific subgroup analyses of circulating EVs, and is expected to offer reliable guidance for cancer diagnoses and management strategies. [ABSTRACT FROM AUTHOR]

Rapid and sensitive analysis of bisphenol A (BPA) is essential for preventing health risks to humans and animals. Hence, a signal-amplified electrochemical aptasensor without repetitive polishing and modification of working electrode was developed for BPA using Au-decorated magnetic reduced graphene oxide (Au/MrGO)-based recognition probe (RP) and DNA nanospheres (DNS)-based signal probe (SP) cooperative signal amplification. The DNS served as a signal molecule carrier and signal amplifier, while Au/MrGO acted as a signal amplifier and excellent medium for magnetic adsorption and separation. Moreover, utilizing the excellent magnetic properties of Au/MrGO eliminates the need for repetitive polishing and multi-step direct modification of the working electrode while ensuring that all detection processes take place in solution and that used Au/MrGO can be easily recycled. The proposed aptasensor exhibited not only good stability and selectivity, but also excellent sensitivity with a limit of detection (LOD) of 8.13 fg/mL (S/N = 3). The aptasensor's practicality was proven by spiking recovery tests on actual water samples and comparing the results with those detected by HPLC. The excellent sensitivity and selectivity make this aptasensor an alternative and promising avenue for rapid detection of BPA in environmental monitoring. [Display omitted] • Working electrode does not require direct modification and repeated polishing. • Dual signal amplification greatly improves sensitivity. • Utilization of magnetism simplifies operation. • The prepared Au/MrGO can be recycled, saving costs. • Good stability and easy operation enhance the practical potential. [ABSTRACT FROM AUTHOR]

Mycotoxins are naturally occurring toxic secondary metabolites produced by fungi in cereals and foodstuffs during the stages of cultivation and storage. Electrochemical biosensing has emerged as a rapid, efficient, and economical approach for the detection and quantification of mycotoxins in different sample media. An electrochemical biosensor consists of two main units, a recognition receptor and a signal transducer. Natural or artificial antibodies, aptamers, molecularly imprinted polymers (MIP), peptides, and DNAzymes have been extensively employed as selective recognition receptors for the electrochemical biosensing of mycotoxins. This article affords a detailed discussion of the recent advances and future prospects of various types of recognition receptors exploited in the electrochemical biosensing of mycotoxins.

Electrochemical biosensors have been widely applied in the development of metabolite detection systems for disease management. However, conventional intravenous and fingertip blood tests are invasive and cannot track dynamic trends of multiple metabolites. Among various body fluids, saliva can be easily accessed and is regarded as a promising candidate for non-invasive metabolite detection. Recent works on the development of electrochemical biosensors for monitoring salivary metabolites have demonstrated high sensitivity and wide linear range. However, most of this research has been focused on salivary detection of a single metabolite. Here, we present a dual-channel electrochemical biosensor for simultaneous detection of lactate and glucose in saliva based on a flexible screen-printed electrode with two working electrodes. The sensitivities of glucose and lactate channels were 18.7 μA/(mM·cm2) and 21.8 μA/(mM·cm2), respectively. The dual-channel biosensor exhibited wide linear ranges of 0–1500 μM for the glucose channel and 0–2000 μM for the lactate channel and the cross-talk between the two detection channels was negligible, which made it adequately suitable for sensing low-level salivary metabolites. Such attractive characteristics demonstrate the potential of this dual-analyte biosensor in the development of wearable devices for monitoring disease progression and fitness. [ABSTRACT FROM AUTHOR]

The role kinases play in regulating cellular processes makes them potential biomarkers for detecting the onset and prognosis of various diseases, including many types of cancer. Current kinase biosensors, including electrochemical and radiometric methods, rely on sensing the ATP‐dependant enzymatic phosphorylation reaction. Here we introduce a new type of interaction‐based electrochemical kinase biosensor that does not require any chemical labelling or modification. The basis for sensing is the interactions between the catalytic site of the kinase and the phosphorylation site of its substrate rather than the phosphorylation reaction. We demonstrated this concept with the ERK2 kinase and its substrate protein HDGF, which is involved in lung cancer. A peptide monolayer derived from the HDGF phosphorylation site was adsorbed onto a gold electrode and was used to sense ERK2 without ATP. The sensitivity of the assay was down to 10 nM of ERK2, corresponding with the range of its cellular concentrations. Surface chemistry analysis confirmed that ERK2 was bound to the HDGF peptide monolayer. This increased the permeability of redox‐active species through the monolayer and resulted in ERK2 electrochemical sensing. Since our detection approach is based on protein‐protein interactions and not on the enzymatic reaction, it can be further utilized for more selective detection of different types of enzymes. [ABSTRACT FROM AUTHOR]

Novel bio‐receptors or bio‐recognition molecular markers with high specificity, stability, and affinity for the efficient binding and entrapment of target biomolecules are essential for developing biomedical devices with high sensitivity and reliability. Aptamers are peptide or nucleic‐acid (DNA or RNA) molecules capable of binding to target biomarkers by forming a unique three‐dimensional structure, providing an effective platform for biosensing. This review comprehensively summarizes the progress of label‐free and label‐based electrochemical aptasensors for the detection of various biomarkers related to cardiovascular diseases. It also outlines the fundamental properties of different cardiac biomarkers, synthesis of target‐specific aptamers, and working principles, such as single receptor and sandwich, of the different types of sensing assays for the electrochemical detection of cardiac biomarkers while highlighting the current challenges and future perspectives. [ABSTRACT FROM AUTHOR]

This work presents an in vivo stem-mounted sensor for Nicotiana tabacum plants and an in situ cell suspension sensor for Solanum lycopersicum cells. Stem-mounted sensors are mechanically stable and less sensitive to plant and air movements than the previously demonstrated leaf-mounted sensors. Interdigitated-electrode-arrays with a dual working electrode configuration were used with an auxiliary electrode and an Ag/AgCl quasi-reference electrode. Signal amplification by redox cycling is demonstrated for a plant-based sensor responding to enzyme expression induced by different cues in the plants. Functional biosensing is demonstrated, first for constitutive enzyme expression and later, for heat-shock-induced enzyme expression in plants. In the cell suspension with redox cycling, positive detection of the enzyme β-glucuronidase (GUS) was observed within a few minutes after applying the substrate (pNPG, 4-Nitrophenyl β-D-glucopyranoside), following redox reactions of the product (p-nitrophenol (pNP)). It is assumed that the initial reaction is the irreversible reduction of pNP to p-hydroxylaminophenol. Next, it can be either oxidized to p-nitrosophenol or dehydrated and oxidized to aminophenol. Both last reactions are reversible and can be used for redox cycling. The dual-electrode redox-cycling electrochemical signal was an order of magnitude larger than that of conventional single-working electrode transducers. A simple model for the gain is presented, predicting that an even larger gain is possible for sub-micron electrodes. In summary, this work demonstrates, for the first time, a redox cycling-based in vivo plant sensor, where diffusion-based amplification occurs inside a tobacco plant’s tissue. The technique can be applied to other plants as well as to medical and environmental monitoring systems.

In the face of complex environments, considerable effort has been made to accomplish sensitive, accurate and highly-effective detection of target analytes. Given the versatility of metal clusters and ligands, high porosity and large specific surface area, metal–organic framework (MOF) provides researchers with prospective solutions for the construction of biosensing platforms. Combined with the benefits of electrochemistry method such as fast response, low cost and simple operation, the untapped applications of MOF for biosensors are worthy to be exploited. Therefore, this review briefly summarizes the preparation methods of electroactive MOF, including synthesize with electroactive ligands/metal ions, functionalization of MOF with biomolecules and modification for MOF composites. Moreover, recent biosensing applications are highlighted in terms of small biomolecules, biomacromolecules, and pathogenic cells. We conclude with a discussion of future challenges and prospects in the field. It aims to offer researchers inspiration to address the issues appropriately in further investigations.

Heterogenizing the molecular catalysts on conductive scaffolds to achieve the isolated molecular dispersion and expected coordination structures is significant yet still challenging. Herein, a sulfur-driving strategy to anchor monodispersed cobalt phthalocyanine on nitrogen and sulfur co-doped graphene (NSG-CoPc) is demonstrated. Experimental and theoretical analysis prove that the incorporation of S dramatically improves the adsorption capability of NSG and evokes the monodispersion of the CoPc molecule, promoting the axial Co─N coordination and the electron delocalization of the Co catalytic center. Benefiting from the reduced activation energy barrier and boosted electron transfer, as well as the maximized active site utilization, NSG-CoPc exhibits outstanding H 2 O 2 oxidization and sensing performance (used as a representative reaction). Moreover, the usage of NSG as a substrate can be readily extended to other metal (Ni, Cu, and Fe) phthalocyanine molecules with molecular-level dispersion. This work clarifies the mechanism of heteroatoms decoration and provides a new paradigm in devising monodispersed molecular catalysts with modulated chemical surroundings for broad applications., (© 2024 Wiley‐VCH GmbH.)

Tremendous efforts have been put into exploring high-entropy alloys (HEAs) for electrocatalysis, which is considered to be a pivotal cornerstone for electrochemical energy conversion. Nevertheless, HEAs have not been employed for electrochemical biosensing and the precise construction of low-dimensional architectures for HEAs is still challenging. Herein, ultrathin quinary PtPdRhCuM (M= Mn, Co or Ni) HEA nanotubes (NTs) with noticeable lattice distortion as well as rich defect sites were controllably synthesized by a template-triggered strategy combining galvanic exchange process, co-reduction pathway and the dealloying technology. Owing to the diversity of composition, high mixing entropy, intrinsic electronic conductivity, and complexity of surface structure, the PtPdRhCuM (M= Mn, Co or Ni) HEA exhibits remarkable physicochemical property and serves as an ultrasensitive sensing layer for the determination of aldicarb sulfone. The acetylcholinesterase (AChE)-Nafion/PtPdRhCuMn HEA NTs-based biosensor possessed a wide detection range of 0.45 pM – 45 nM with a low detection limit of 86.5 fM for aldicarb sulfone. Moreover, the established biosensor was applicable to pesticides in real food samples (apple and cucumber) with excellent recoveries (99.87 − 101.49% and 97.95 − 104.56%). This work forms the foundation for employing HEAs as electrode material for widespread applications such as electrochemical aldicarb sulfone sensing. • PtPdRhCuM high entropy alloy nanotubes with rich defects were controllably synthesized. • The ultrathin HEA NTs possessed abundant active sites, excellent electronic conductivity. • The fabricated electrochemical sensing platform exhibits high sensitivity and a low detection limit. [ABSTRACT FROM AUTHOR]

[Display omitted] • The PAMAM@MXene was prepared by a cost-effective and in-situ growth approach. • A high-performance electrochemical sensor was constructed based on PAMAM@MXene. • It exhibited superior sensitivity and wide detection range to folate receptor. • A facile, stable and efficient folate receptor assay was proposed. The level of folate receptor (FR) has become one of the independent factors for measuring human tumor diseases. The precise quantification of FR is helpful for the early diagnosis and subsequent treatment of tumors. The modification of electrodes is a key issue in ensuring and enhancing the electrochemical biosensing ability. In this study, we in-situ synthesized a nanocomposite material with excellent conductivity and stability by grafting first-generation poly(amidoamine) dendrimers onto the MXene (Ti 3 C 2 T X) as the immobilized matrix (PAMAM@MXene). An electrochemical sensor was developed for FR monitor by loading the PAMAM@MXene on screen-printed carbon electrodes (SPCEs). Scanning electron microscopy (SEM) supported the effective synthesis of PAMAM@MXene. Under optimal conditions, the prepared sensor achieved the quantification of FR with a wide range of concentrations from 10 ng/mL to 1000 ng/mL with a detection limit (LOD) of 5.6 ng/mL. It also exhibited satisfactory selectivity, reproducibility, and stability, which provided the possibility for expanding new pathways in the detection of clinical FR. [ABSTRACT FROM AUTHOR]

The self-healing mechanism and bioelectrochemical interface properties of a series of core–shell guanosine-borate supramolecular hydrogels were throughly studied. The self-healing mechanism and bioelectrochemical interface properties of supramolecular gels have been rarely explored. In this context, we propose a constitutive "fibril-reorganization" model to reveal the self-healing mechanism of a series of core–shell structured guanosine-borate (GB) hydrogels and emphasize that interfibrillar interactions at the supramolecular polymer scale (G-quadruplex nanowires) drive the self-healing process of GB hydrogels. Structure-electrochemical sensing performance studies reveal that GB hydrogel nanofibers with relatively strong biomolecular affinity such as –SH modified GB hydrogel (GB-SH) show a high sensitivity of response and low limit of detection for tumour marker alpha-fetoprotein sensing (AFP; 0.076 pg mL−1). Guanosine/ferroceneboronic acid (GB-Fc) hydrogel nanofibers with superior conductivity and redox activity display the widest linear detection range for AFP (0.0005–100 ng mL−1). Structure-property correlations of GB hydrogels provide useful insight for the future design of advanced self-healing materials and electrochemical biosensors. [ABSTRACT FROM AUTHOR]

Electrochemical biosensors have been widely applied in the development of metabolite detection systems for disease management. However, conventional intravenous and fingertip blood tests are invasive and cannot track dynamic trends of multiple metabolites. Among various body fluids, saliva can be easily accessed and is regarded as a promising candidate for non-invasive metabolite detection. Recent works on the development of electrochemical biosensors for monitoring salivary metabolites have demonstrated high sensitivity and wide linear range. However, most of this research has been focused on salivary detection of a single metabolite. Here, we present a dual-channel electrochemical biosensor for simultaneous detection of lactate and glucose in saliva based on a flexible screen-printed electrode with two working electrodes. The sensitivities of glucose and lactate channels were 18.7 μA/(mM·cm2) and 21.8 μA/(mM·cm2), respectively. The dual-channel biosensor exhibited wide linear ranges of 0–1500 μM for the glucose channel and 0–2000 μM for the lactate channel and the cross-talk between the two detection channels was negligible, which made it adequately suitable for sensing low-level salivary metabolites. Such attractive characteristics demonstrate the potential of this dual-analyte biosensor in the development of wearable devices for monitoring disease progression and fitness.

Dynamic and on‐site analysis of serum from human blood is crucial, however, state‐of‐the‐art blood‐assay methods can only collect single or discrete data of physiological analytes; thus, the online reports of the dynamic fluctuation of key analytes remains a great challenge. Here, we propose a novel separation‐sensing membrane by constructing a heterogeneous‐nanostructured architecture, wherein a surface nanoporous layer continuously extracts serum, while the biosensing nanochannels underneath dynamically recognise biotargets, thereby achieving a continuous testing of vital clinical indices as blood is drawn. By precisely controlling the pore structure and nanoshape of biosensing crystals, this membrane achieved accurate and online glucose and lactate monitoring in patients with a variety of medical conditions within 1 min, which is one order of magnitude faster than state‐of‐the‐art techniques. Moreover, various kinds of bio‐recognisers can be introduced into this membrane to accurately detect glutamate, transaminase, and cancer biomarkers. [ABSTRACT FROM AUTHOR]

Early detection and effective treatment are crucial to reduce the physical, emotional, and financial pressure exerted by growing cancer burden on individuals, families, communities, and health systems. Currently, it is clear that the accurate analysis of emerging cancer epigenetic and metastatic-related biomarkers at different molecular levels is envisaged as an exceptional solution for early and reliable diagnosis and the improvement of therapy efficiency through personalized treatments. Within this field, electrochemical biosensing has demonstrated to be competitive over other emerging and currently used methodologies for the determination of these biomarkers accomplishing the premises of user-friendly, multiplexing ability, simplicity, reduced costs and decentralized analysis, demanded by clinical oncology, thus priming electrochemical biosensors to spark a diagnostic revolution for cancer prediction and eradication. This review article critically discusses the main characteristics, opportunities and versatility exhibited by electrochemical biosensing, through highlighting representative examples published during the last two years, for the reliable determination of these emerging biomarkers, with great diagnostic, predictive and prognostic potential. Special attention is paid on electrochemical affinity biosensors developed for the single or multiplexed determination of methylation events, non-coding RNAs, ctDNA features and metastasis-related protein biomarkers both in liquid and solid biopsies of cancer patients. The main challenges to which further work must be addressed and the impact of these advances should have in the clinical acceptance of these emerging biomarkers are also discussed which decisively will contribute to understand the molecular basis involved in the epigenetics and metastasis of cancer and to apply more efficient personalized therapies. Electrochemical biosensing to move forward in cancer epigenetics and metastasis. Image 1 • Accurate analysis of cancer epigenetic and metastatic-related biomarkers. • User-friendly, multiplexing ability, simplicity, reduced costs and decentralized analysis. • Opportunities and versatility exhibited by electrochemical biosensing in this field. • Representative examples published during the last two years. • Main challenges to solve and future impact and prospects. [ABSTRACT FROM AUTHOR]

Colony plate counting still remains the "gold standard" procedure for the identification of viable Listeria monocytogenes cells and to address microbiological quality assurance of foodstuff. However, this classical method requires an analysis time superior to the current demands in food industry. Hence, new time-enhanced methods based on improved cultural techniques, nucleic acid detection and immunological assays have raised as new validated alternatives. Nevertheless, those rapid methods still require specific and expensive equipment and imply a considerable workload. In the last years, electrochemical biosensors and bioassays have been intensively investigated, emerging as excellent alternatives to surpass the disadvantages of the conventional and standard rapid methods. They provide the desired fast, sensitive and selective response, towards a portable, cost-effective and user-friendly performance. Therefore, in this work, a comprehensive review about the foundations, current achievements and limitations described over the past fifteen years for electrochemical biosensing of Listeria monocytogenes in food products is presented. The latest innovations rely on the use of low-cost electrochemical transducers, integration of novel (nano)materials and incorporation of new bioreceptors in the sensing strategy. Single-cell detection and intelligent packaging are also growing trends. Regardless of the remaining challenges, that still need to be overcome, electrochemical biosensing seems to have a role as one of the promising strategies to lead the future of foodborne pathogen analysis. Image 1 • The established analytical methods for Listeria monocytogenes detection presents important limitations. • The development of highly sensitive and time-enhanced alternative strategies is of utmost importance. • Electrochemical biosensing techniques are gaining attention as promising approaches for Listeria monocytogenes analysis. • The recent and future advances in electrochemical biosensing to address foodborne pathogens detection have been reviewed. [ABSTRACT FROM AUTHOR]

Three 1D/2D HgII coordination polymers (CPs), namely {[Hg3(L)2Cl6](H2O)}n (1), [Hg(L)Br2]n (2), and [Hg(L)I2]n (3) were prepared by assembly of 3,4‐bis(3‐pyridyl)‐5‐(4‐pyridyl)‐1,2,4‐triazole (L) with different inorganic HgII salts (i.e. HgCl2, HgBr2 or HgI2). Single‐crystal X‐ray diffraction analysis reveals two types of bimetallic subunits [(Hg)2C6N4] and [(Hg)2C12N6] in CP 1, which are further extended to a 2D coordination network. Both of CPs 2 and 3 show 1D zigzag arrays bridged by L ligands. Notably, the L ligands take the (η4, μ4) coordination fashion in 1 but (η2, μ2) binding mode in 2 and 3. The structural differences of CPs 1–3 indicate that the L ligand can adjust its coordination fashions to meet the requirements of HgII centers, relying on the presence of distinct halide anions. In addition, 1 can be applied to fabricate an electrochemical biosensor for the detection of penicillin. [ABSTRACT FROM AUTHOR]