Search

Metasurface that achieves extraordinary terahertz transmission (ETT) and local electric field enhancement (FE) holds significant potential for terahertz studies involving extremely low concentrations of target materials. In this study, we explore a composite aperture metasurface capable of both ETT and local FE. By inserting bow-tie apertures in the "minimum-resonance" zone between four adjacent rhombic lattices, a local FE factor is achieved. Notably, adjusting the configuration of the bow-tie aperture enhances the coupling between surface plasmons, thereby expanding the transmission bandwidth. Through parameter optimization, the metasurface achieves a peak transmission exceeding 95% and a transmittance above 80% in the frequency range of 2.44–3.65 THz, while simultaneously exhibiting a maximum local FE factor of 1005 at 3.45 THz. This approach offers a promising avenue for the design of metasurfaces for spectroscopy and biosensor applications. [ABSTRACT FROM AUTHOR]

One-dimensional plasmonic nanogratings (1D-PNGs) with high aspect ratios and narrow grooves promise enhanced coupling for hybrid graphene systems with the localized surface plasmon of the metallic grating and graphene surface plasmons. However, both the fabrication of the 1D-PNG and the application of graphene to it are difficult. We developed 1D-PNGs with a high aspect ratio of 15 and narrow grooves of 100 nm in width using the tapered mold method and a dry graphene-transfer procedure. Raman spectroscopy measurements showed that monolayer graphene was successfully transferred onto the 1D-PNGs, and the graphene was strongly doped with Au in the 1D-PNGs. Graphene on narrow grooves (free-standing graphene) demonstrated an almost identical p-doping level to graphene on Au because the narrow groove width allowed sufficient doping by Au for graphene on grooves. Reflectance measurements showed that the 1D-PNGs exhibited polarization- and wavelength-selective absorption at infrared (IR) wavelengths, and the effect of graphene blue-shifted the absorption peak wavelength induced by the surface plasmon resonance of 1D-PNGs. Numerical calculations agree well with these experimental results and indicate that the electric field strongly localizes on graphene in the grooves. Moreover, the doping level tunes the absorption wavelength owing to the coupling with graphene plasmons and the surface plasmon resonance of 1D-PNGs. This could provide electrical tunability to the graphene plasmons. Our fabrication procedure produced hybrid graphene-1D-PNGs with high aspect ratios and narrow groove systems for IR wavelengths. This system can contribute to developing high-performance electrically tunable graphene-based IR photodetectors, tunable IR emitters/absorbers, and biological sensors. [ABSTRACT FROM AUTHOR]

Theoretical models have predicted that pH-responsive surface groups can reduce the sensitivity of field-effect transistor biosensors. However, attempts to prove this experimentally have shown conflicting results. In this work, a graphene field effect transistor (gFET) biosensor is used, which, without modification, is pH insensitive. The surface of the graphene is then functionalized using 1-hydroxypyrene to modulate the pH sensitivity of the gFET. A pH sensitivity ranging from 3.9 to 36.8 mV/pH was demonstrated. The biosensitivity of the gFETs was tested using streptavidin–biotin as a model system. The experimental results showed no correlation between biosensitivity and pH sensitivity. An electrochemical membrane model was used to determine the expected relationship between biosensitivity and pH sensitivity. The model results show that biosensitivity does not decrease until a certain threshold pH sensitivity is reached. This threshold is dependent on factors such as the acid dissociation constants of the surface hydroxyl groups and ion concentration. Furthermore, the differences between the simulation and experiment suggest that the effect of screening is greatly reduced when the analyte binds within a membrane. [ABSTRACT FROM AUTHOR]

M. tuberculosis is the contributive factor to tuberculosis (TB), which is the foremost death reason attributable to a sole communicable agent and has claimed the lives of millions of people in the past decade. Therefore, it is crucial to discover this bacterial infection as soon as possible to receive quick and proper treatment for patients, as well as for preventing illness propagation. Around 98% of cases of TB are verified in underdeveloped nations, and the development of reliable biosensor-based diagnostic approaches is critical because of the unavailability of well-equipped detecting laboratories for this bacterium. The time between infection and treatment for tuberculosis (TB) is reduced if the disease is detected early. The bulk of traditional Mtb detection technologies, on the other hand, fall short of the parameters for real TB detection. To address these restrictions, newly developing point-of-care devices called biosensors are necessary. Various biosensors that detect the Mtb are summarised in this review having numerous advantages such as low cost, early detection, rapid, simple, no expensive instruments are required, no need for experts, easy to handle, sensitive, specific, portable, reliable, affordable, etc. In this review, first section is all about the introduction and second part depicts the M. tuberculosis (Mtb) based traditional detection methods along with their advantages and disadvantages. The last portion of this review summarised the recently developed M. tuberculosis (Mtb) based biosensor. [ABSTRACT FROM AUTHOR]

Progress in synthetic biology and nanotechnology plays at present a major role in the fabrication of sophisticated and miniaturized analytical devices that provide the means to tackle the need for new tools and methods for environmental and food safety. Significant research efforts have led to biosensing experiments experiencing a remarkable growth with the development and application of recombinant luminescent proteins (RLPs) being at the core of this boost. Integrating RLPs into biosensors has resulted in highly versatile detection platforms. These platforms include luminescent enzyme-linked immunosorbent assays (ELISAs), bioluminescence resonance energy transfer (BRET)–based sensors, and genetically encoded luminescent biosensors. Increased signal-to-noise ratios, rapid response times, and the ability to monitor dynamic biological processes in live cells are advantages inherent to the approaches mentioned above. Furthermore, novel fusion proteins and optimized expression systems to improve their stability, brightness, and spectral properties have enhanced the performance and pertinence of luminescent biosensors in diverse fields. This review highlights recent progress in RLP-based biosensing, showcasing their implementation for monitoring different contaminants commonly found in food and environmental samples. Future perspectives and potential challenges in these two areas of interest are also addressed, providing a comprehensive overview of the current state and a forecast of the biosensing strategies using recombinant luminescent proteins to come. [ABSTRACT FROM AUTHOR]

Monitoring cell secretion in complex microenvironments is crucial for understanding cellular behavior and advancing physiological and pathological research. While traditional cell culture methods, including organoids and spheroids, provide valuable models, real-time monitoring of cell secretion of signaling molecules remains challenging. Integrating advanced monitoring technologies into these systems often disrupts the delicate balance of the microenvironment, making it difficult to achieve sensitivity and specificity. This review explored recent strategies for integrating the monitoring of cell secretion of signaling molecules, crucial for understanding and replicating cell microenvironments, within cell culture platforms, addressing challenges such as non-adherent cell models and the focus on single-cell methodologies. We highlight advancements in biosensors, microfluidics, and three-dimensional culture methods, and discuss their potential to enhance real-time, multiplexed cell monitoring. By examining the advantages, limitations, and future prospects of these technologies, we aim to contribute to the development of integrated systems that facilitate comprehensive cell monitoring, ultimately advancing biological research and pharmaceutical development. [ABSTRACT FROM AUTHOR]

The biosensor, named "virusmeter" in this study, integrates quartz crystal microbalance technology with an immune-functionalized chip to distinguish between symptomatic patients with respiratory diseases and healthy individuals by analyzing exhaled air samples. Renowned for its compact design, rapidity, and noninvasive nature, this device yields results within a 5-min timeframe. Evaluated under controlled conditions with 54 hospitalized symptomatic COVID-19 patients and 128 control subjects, the biosensor demonstrated good overall sensitivity (98.15%, 95% CI 90.1–100.0) and specificity (96.87%, 95% CI 92.2–99.1). This proof-of-concept presents an innovative approach with significant potential for leveraging piezoelectric sensors to diagnose respiratory diseases. [ABSTRACT FROM AUTHOR]

Optical biosensors have employed at least three distinct system architectures over the last 40 years, moving from "sample in-answer out" systems to completely embedding the optical biosensor into the sample to embedding the recognition module in the sample and optically interrogating the recognition module from outside of the sample. This trends article provides an overview of the evolution of these three system architectures and discusses how each architecture has been applied to solve the measurement challenges of a wide variety of applications. A fourth biosensor system architecture, that of an "autonomous" biosensor which "takes the user out of the loop" while both detecting target analytes and responding to that measurement, is currently under development for applications initially including environmental cleanup and "smart therapeutics." As is the case in many other areas of technology, it will be profoundly interesting to observe the further development and application of elegant, simpler (optical) biosensor systems to address tomorrow's measurement needs. [ABSTRACT FROM AUTHOR]

Nucleic acid‐templated reactions are chemical processes driven by the increased effective concentration of reactants on nucleic acids through the sequence‐specific hybridization of nucleic acids. Because these reactions translate the signals of target nucleic acids to detectable specific outputs, such as fluorescence, they can be applied for nucleic acid sensing and imaging. Owing to their advantageous features, such as signal amplification, isothermal nonenzymatic operation, and diverse reaction outputs and designs, the templated reactions have considerable potential for designing next‐generation nucleic acid sensors with high sensitivity, selectivity, rapidity, and user‐friendliness. Thus, over the past two decades, numerous templated reactions have been developed for more efficient nucleic acid detection. This review highlights recent advances in nucleic acid‐templated reactions since 2020, focusing on the newly developed reactions and strategies for designing highly sensitive, selective, and accurate nucleic acid sensing systems. We also summarize templated reaction research since 2015 and explore how integrating these reactions with other signal amplification systems and readout methods has led to the development of practical nucleic acid sensors with improved properties. According to the analysis of each type of templated reactions (ligation, releasing, and transformation), design trends are discussed that inform the outlook for the future development of nucleic acid sensors utilizing templated reactions. [ABSTRACT FROM AUTHOR]

Comprehensive Summary Imbalance in the levels of ascorbic acid (AA) can pose a risk to human health. Therefore, it's essential to establish an accurate method for the detection of AA. In this work, a novel N‐doped carbon composite (MnOx@NC) with dual enzyme‐like activities to detect AA was prepared by calcination of Mn‐MOF containing H3TTPCA ligand. Interestingly, the •O2− that leads to its oxidase‐like activity was not formed by dissolved oxygen, but came from the synergistic effect of lattice oxygen generated by calcination and the transformation of MnII/MnIII/MnIV, and the presence of H2O2 provided much •OH, which caused its peroxidase‐like activity. Meanwhile, the residual N element came from H3TTPCA ligand assisted the catalytic process. Accordingly, a dual‐signal sensing platform and smartphone‐assisted recognition for detection of AA was developed and a colorimetric sensor array was established to distinguish three antioxidants. This work also demonstrates considerable promise for the detection of AA in authentic pharmaceuticals. [ABSTRACT FROM AUTHOR]

In the current study, a Novel synthesis of fluorescent Green carbon dots (G‐NCDs) is reported from waste Brachyura shells using a simple, green technique. G‐NCDs function as a TURN‐ON fluorescent probe for the selective detection Uric Acid (UA) in presence of Dopamine (DA). The synthesized carbon dots are sand colored under visible light and exhibit pale green fluorescence under UV radiation. The G‐NCDs are characterized using UV–vis, FTIR, XPS, SEM‐EDAX, HR‐TEM, X‐ray diffraction, and PL spectroscopic technique. The SEM‐EDAX data of G‐NCDs shows a layered, fibrous morphology and confirms the presence of only Carbon, Nitrogen, and Oxygen in the matrix. FTIR and XPS response confirms the presence of functional groups like ─C≡N, ─C≡C─, CH, ═C─H, O─H on the surface of G‐NCDs. XRD data confirms G‐NCDs to be crystalline with a particle size of 4.51 nm. The quantum yield found to be 99.8%. PL response confirms a TURN OFF fluorescence with increased addition of DA. Fluorescence resonance energy transfer (FRET), a form of dynamic quenching is responsible for the DA quenching, confirmed through linear Stern‐ Volmer plot. With increase in addition of UA in presence of DA fluorescence TURNs ON with a minimum selective detection limit of UA as 0.23 × 10−12 M. Selective detection of UA in presence of DA is due to the following reasons i) decrease in bandgap of G‐NCDs in presence of UA ii) electrostatic attraction between negatively charged carboxyl group of G‐NCDs and positively charge secondary amine group of UA molecule ii) UA molecules near to the surface of G‐NCDs switches off the formation of polydopamine iv) formation of surface defects due to the formation of hydrogen bonds between the ketone/hydroxyl group in the UA molecule and the amino group on the surface of G‐NCD resulting in fluorescence. The first time the lowest detection limit of 0.23 × 10−12 M of UA is been reported in presence of DA using G‐NCDs. In future, G‐NCDs will be used for the detection of UA in biological fluids. [ABSTRACT FROM AUTHOR]

2‐Aminopurine (2AP) is a fluorescent analog of adenine, and its unique properties make it valuable in various biochemical and biotechnological applications. Its fluorescence property probes local dynamics in DNA and RNA because stacking with the surrounding bases quench its fluorescence. 2AP‐labeled DNA or RNA sequences have been used for the detection of genetic mutations, viral RNA, or other nucleic acid‐based markers associated with diseases like cancer and infectious diseases. In this study, we isolated aptamers for 2AP using the library immobilization capture‐SELEX technique. A dominating aptamer family was isolated after 15 rounds of selection. The Kd values for the most abundant 2AP1 aptamer are 209 nM in a fluorescence assay and 72 nM in an isothermal titration calorimetry test. A 32 nM 2AP limit of detection was tested based on its intrinsic fluorescence change upon aptamer binding. Additionally, we conducted some mutation analysis. Furthermore, we tested the selectivity of this aptamer and discovered that it can bind adenine and adenosine with approximately 100‐fold lower affinity than 2AP. [ABSTRACT FROM AUTHOR]

Attaching DNA oligonucleotides to gold nanoparticles (AuNPs) to prepare spherical nucleic acids (SNAs) has offered tremendous insights into surface chemistry with resulting bioconjugates serving as critical reagents in biosensors and nanotechnology. While thiolated DNA is generally required to achieve stable conjugates, we herein communicate that using a thermal drying method, a high DNA density and excellent SNA stability was achieved using nonthiolated DNA, rivaling the performance of thiolated DNA such as surviving 1 M NaCl, 2 month stability in 0.3 M NaCl and working in 50 % serum. A poly‐adenine block with as few as two consecutive terminal adenine bases is sufficient for anchoring on AuNPs. By side‐by‐side comparison with the salt‐aging method, the conjugation mechanism was attributed to competitive adenine adsorption at high temperature along with an extremely high DNA concentration upon drying. Bioanalytical applications of nonthiolated SNAs were validated in both solution and paper‐based sensor platforms, facilitating cost‐effective applications for SNAs. [ABSTRACT FROM AUTHOR]

Worldwide, the current performance of fungal infection and especially drug-resistant fungal infection diagnosis is poor. Molecular DNA-based identification and characterization of fungal pathogens have emerged as fast and informative approaches. Some laboratory DNA technologies are amenable to miniaturization and portability. However, development of a sample-in–answer-out portable fungal diagnosis tool still faces several challenges, mainly resulting from the complexity of fungal biology. Several inexpensive proof-of-concept, portable diagnosis systems have been developed for viral, bacterial, and plasmodial infections. These serve as inspiration for the unaddressed needs in medical mycology. Recent developments in the miniaturization of cell capture, cell lysis, and DNA detection protocols bring cost-effective and widespread molecular fungal diagnosis closer to reality. The diagnosis of fungal infections presents several challenges and limitations, stemming from the similarities in symptomatology, diversity of underlying pathogenic species, complexity of fungal biology, and scarcity of rapid, affordable, and point-of-care approaches. In this review, we assess technological advances enabling the conversion of cutting-edge laboratory molecular diagnostic methods to cost-effective microfluidic devices. The most promising strategies toward the design of DNA sequence-based fungal diagnostic systems, capable of capturing and deciphering the highly informative DNA of the pathogen and adapted for resource-limited settings, are discussed, bridging fungal biology, molecular genetics, microfluidics, and biosensors. [ABSTRACT FROM AUTHOR]

Biofilm formation is a widespread phenomenon in the microbial world. They may affect human and animal health and cause damage to various industries; at the same time, they can be useful in such fields as wastewater treatment or improving bioavailability of nutrients for plants. This fact actualizes the development of methods for studying biofilms. The present work is the first report on an optical sensor technique for the indication of bacterial biofilm formation with regard to biological variability, using plant growth-promoting rhizobacteria of the genus Azospirillum as a model. The correlation was found between the changes in electrophysical parameters recorded by the sensor system and the morphological features of bacteria from planktonic and/or biofilm cultures: the presence of motile organelles (flagella), polymorphism, and ultrastructure of cellular forms. It was established that the profiles of microbial cells recorded by the optical system were significantly different in planktonic and biofilm forms. When comparing the cells of different strains (the parental strain and its derivatives), or planktonic and biofilm bacteria, the variables recorded by the electro-optical sensor system were in agreement with the changes in bacterial micro- and ultrastructure recorded by other techniques. The results of analysis of the electrophysical profiles of A. baldaniorum Sp245 can be used as reference for revealing specific interactions between biofilm cells of this strain and various root surface components of a putative plant partner using an optical sensor system. [ABSTRACT FROM AUTHOR]

Gynecological cancers, including cervical, endometrial, and ovarian cancer, contribute to a significant portion of female cancer-related deaths. Despite advancements in cancer detection, these diseases continue to pose challenges due to limited cost-effective screening methods and late-stage diagnoses. This review paper focuses on the utilization of microfluidic devices (MFDs) as a cost-effective tool for diagnosing and screening gynecological cancers. MFDs are portable instruments capable of sample separation, extraction, dilution, mixing, and biomarker detection. Their compact size and efficiency make them advantageous for comprehensive sample analysis. The emergence of microfluidic point-of-care devices offers potential for developing biomarker-based screening technologies and facilitating early detection of gynecological cancers. This paper aims to consolidate the knowledge and findings surrounding the utilization of MFDs in gynecological cancer research by summarizing the current literatures that exist between 2006 and 2023. The review of previous research in this area will contribute to a comprehensive understanding of the recent state of utilizing MFDs for gynecological cancer screening and detection as it will shed light on the advancements made thus far and provide insights into the future prospects and potential directions of research in this field. [ABSTRACT FROM AUTHOR]

l-asparaginases catalyze the conversion of l-asparagine to aspartate. Their potential as antineoplastic drug and as a processing aid for acrylamide mitigation during food processing has created a special interest. These applications require l-asparaginases with longer half-lives and no or negligible catalytic activity against other amino acids. Hyperthermophilic archaea are promising source of such l-asparaginases. Analysis of genome sequences revealed that most of the hyperthermophilic archaea contain more than one type of l-asparaginase. Indeed, two types of l-asparaginases, a bacterial-type I and a plant-type, have been characterized from a few archaeal members. This article is an attempt to summarize the current understanding of thermophilic archaeal l-asparaginases with emphasis on structural insights and potential functional applications. [ABSTRACT FROM AUTHOR]

Continuous monitoring of pathogens finds applications in environmental, medical, and food industry settings. Quartz crystal microbalance (QCM) is one of the promising methods for real-time detection of bacteria and viruses. QCM is a technology that utilizes piezoelectric principles to measure mass and is commonly used in detecting the mass of chemicals adhering to a surface. Due to its high sensitivity and rapid detection times, QCM biosensors have attracted considerable attention as a potential method for detecting infections early and tracking the course of diseases, making it a promising tool for global public health professionals in the fight against infectious diseases. This review first provides an overview of the QCM biosensing method, including its principle of operation, various recognition elements used in biosensor creation, and its limitations and then summarizes notable examples of QCM biosensors for pathogens, focusing on microfluidic magnetic separation techniques as a promising tool in the pretreatment of samples. The review explores the use of QCM sensors in detecting pathogens in various samples, such as food, wastewater, and biological samples. The review also discusses the use of magnetic nanoparticles for sample preparation in QCM biosensors and their integration into microfluidic devices for automated detection of pathogens and highlights the importance of accurate and sensitive detection methods for early diagnosis of infections and the need for point-of-care approaches to simplify and reduce the cost of operation. [ABSTRACT FROM AUTHOR]

In this work, a Dielectrically Modulated Junctionless Rectangular Gate All Around Field Effect Transistor (DM-JLRGAA-FET) is demonstrated and explored for label free detection of neutral biomolecules. In comparison to its conventional architectures, proposed biosensor exhibits a significantly improved sensing and conjugation performance due to its remarkable structure, which enhances its performance by providing substantial rejection to SCEs (short channel effects) and strengthened gate control over channel electrostatics. Drain current sensitivity, surface potential, transconductance and output conductance are employed to determine the sensing competence of the proposed biosensor. The proposed biosensor offers maximum drain current sensitivity of 8.09 for keratin biomolecule. The detection will become quite difficult during conjugation of two or more biomolecules. The conjugation analysis is also investigated by effective dielectric constant approach governed by Bruggeman's Model. The conjugations of Streptavidin-Keratin and Streptavidin-Zein is studied for various concentration in the cavity. Conjugations of Streptavidin and Keratin shows the highest sensitivity of 18.5%. The sensing performance of proposed biosensor is optimized for schottky source/drain contacts engineering and also for channel material engineering. [ABSTRACT FROM AUTHOR]

In this paper, we aimed to develop a trusted secured routing Ad-hoc ondemand distance vector (AODV) protocol to fight against blackhole attacks within the wireless body area network (WBAN). The trusted secure routing protocol incorporates a routing strategy based on trust value to detect malicious nodes based on their trust value, a routing technique based on node residual energy to select the node with the highest residual energy during the communication process, and a hybrid cryptography algorithm that merges the Affine cipher with the modified RSA cipher algorithm to secure communication against malevolent biomedical sensor attacks. Simulation outcomes demonstrate that the suggested protocol outperforms the traditional AODV routing protocol in all evaluation metrics, including data rate, energy consumption, and packet delivery ratio. Its main strength is that it considers several factors, like illegitimate medical sensor detection, efficient network energy use, and secure data transmission, unlike similar secured routing protocols. Furthermore, the hybrid cipher algorithm improves the effectiveness and increases the security level of sensitive data compared to traditional cipher algorithms such as the Affine cipher and the RSA cipher. [ABSTRACT FROM AUTHOR]

A nonenzymatic electrochemical lactic acid sensor was fabricated by electrodepositing gold microflowers on a screen‐printed carbon electrode and used to determine lactic acid in human serum and sweat quantitatively. Extensive voltammetric studies with lactic acid in phosphate‐buffer saline (PBS) and the analysis of the reduction product proved beyond doubt that lactic acid undergoes two‐electron reduction to form lactaldehyde. The reduction current increased quantitively with lactic acid concentration from 0.5–8.5 mM in 0.1 M PBS. The sensor showed excellent sensitivities of 1243 μA mM−1 cm−2 and 2752 μA mM−1 cm−2 in two linear ranges, 0.5–2.5 mM and 2.5–8.5 mM, respectively with a detection limit of 0.012±0.0014 mM. The performance of the sensor was validated by estimating lactic acid in human serum and the sweat generated through physical exercise. The estimated lactic acid concentrations are in good agreement with clinical analysis data. This indicates the potential applicability of the sensor in the point‐of‐care detection of lactic acid. [ABSTRACT FROM AUTHOR]

Disposable electrochemical biosensors with high sensitivity are very fit for point-of-care testing in clinical diagnosis. Herein, amino-functionalized, vertically ordered mesoporous silica films (NH2-VMSF) attached to an electrochemically polarized screen-printed carbon electrode (p-SPCE) are prepared using a simple electrochemical method and then utilized to construct a gated electrochemical aptasensor for rapid and sensitive determination of carcinoembryonic antigen (CEA). After being treated with the electrochemical polarization procedure, p-SPCE has plentiful oxygen-containing groups and improved catalytic ability, which help promote the stability of NH2-VMSF on SPCE without the use of an adhesive layer and simultaneously generate a highly electroactive sensing interface. Owing to the numerous uniform and ultrasmall nanopores of NH2-VMSF, CEA-specific aptamer anchored on the external surface of NH2-VMSF/p-SPCE serves as the gatekeeper, allowing the specific recognition and binding of CEA and eventually impeding the ingress of electrochemical probes [Fe(CN)63−/4−] through the silica nanochannels. The declined electrochemical responses of Fe(CN)63−/4− can be used to quantitatively detect CEA, yielding a wide detection range (100 fg/mL to 100 ng/mL) and a low limit of detection (24 fg/mL). Moreover, the proposed NH2-VMSF/p-SPCE-based electrochemical aptasensor can be applied to detect the amount of CEA in spiked human serum samples, which extends the biological application of a disposable NH2-VMSF/p-SPCE sensor by modulating the biological recognition species. [ABSTRACT FROM AUTHOR]

The demand for continuous monitoring of biochemical markers for diagnostic purposes is increasing as it overcomes the limitations of traditional intermittent measurements. This study introduces a method for long‐term, continuous plasmonic biosensing of oligonucleotides with high temporal resolution. Our method is based on a regeneration‐based reversibility approach that ensures rapid reversibility in less than 1 minute, allowing the sensor to fully reset after each measurement. We investigated label‐free and AuNP enhancements for different dynamic ranges and sensitivities, achieving a limit of detection down to pM levels. We developed a regeneration‐based reversibility approach for continuous biosensing, optimizing buffer conditions using the Taguchi method to achieve rapid, consistent reversibility, ensuring reliable performance for long‐term monitoring. We detected oligonucleotides in buffered and complex solutions, including undiluted and unfiltered human serum, for up to 100 sampling cycles in a day. Moreover, we showed the long‐term stability of the sensor for monitoring capabilities in buffered solutions and human serum, with minimal signal value drift and excellent sensor reversibility for up to 9 days. Our method opens the door to new prospects in continuous biosensing by providing insights beyond intermittent measurements for numerous analytical and diagnostic applications. [ABSTRACT FROM AUTHOR]

A clever approach for biosensing is to leverage the concept of the proximity effect, where analyte binding to probes can be coupled to a second, controlled binding event such as short DNA strands. This analyte-dependent effect has been exploited in various sensors with optical or electrochemical readouts. Electrochemical proximity assays (ECPA) are more amenable to miniaturization and adaptation to the point-of-care, yet ECPA has been generally targeted toward protein sensing with antibody-oligonucleotide probes. Antibodies themselves are also important as biomarkers, since they are produced in bodily fluids in response to various diseases or infections, often in low amounts. In this work, by using antigen-DNA conjugates, we targeted an ECPA method for antibody sensing and showed that the assay performance can be greatly enhanced using flexible spacers in the DNA conjugates. After adding flexible polyethylene glycol (PEG) spacers at two distinct positions, the spacers ultimately increased the antibody-dependent current by a factor of 4.0 without significant background increases, similar to our recent work using thermofluorimetric analysis (TFA). The optimized ECPA was applied to anti-digoxigenin antibody quantification at concentrations ranging over two orders of magnitude, from the limit of detection of 300 pM up to 50 nM. The assay was functional in 90% human serum, where increased ionic strength was used to counteract double-layer repulsion effects at the electrode. This flexible-probe ECPA methodology should be useful for sensing other antibodies in the future with high sensitivity, and the mechanism for signal improvement with probe flexibility may be applicable to other DNA-based electrochemical sensor platforms. [ABSTRACT FROM AUTHOR]

In this study, the impact of glucocorticoid, betamethasone dipropionate on enzyme activity in vitro and its effects on hematological parameters in vivo was investigated. The immobilized catalase, crucial for cell oxidative stress response via hydrogen peroxide reduction, exhibited a robust electrocatalytic response, maintaining its biological activity. The in vitro inhibition kinetics of catalase, as determined by electrocatalytic methods and expressed using Lineweaver-Burke diagrams, revealed an uncompetitive type of inhibition with altered Imax and Km in the presence of a range of betamethasone dipropionate concentrations. The in vivo experiments conducted on Rattus norvegicus demonstrated significant alterations in hematological parameters following betamethasone dipropionate administration. These changes included a decrease in erythrocyte count, an increase in hemoglobin, a reduction in mean corpuscular volume (MCV), and an elevation in mean corpuscular hemoglobin (MCH) and mean corpuscular hemoglobin concentration (MCHC). Notably, the leukocyte counts substantially increased. The observed hematological shifts suggest an impact of betamethasone dipropionate on the hematopoietic system, reinforcing the need for cautious corticosteroid administration. The findings underline the necessity for judicious corticosteroid treatment, acknowledging both enzymatic and systemic repercussions. [ABSTRACT FROM AUTHOR]

Co‐contamination of mycotoxins produced by fungi in foodstuffs and feeds causes a tremendous health risk to humans and animals. The simultaneous detection of multiple mycotoxins using a cost‐effective and point‐of‐care technology is key to ensuring food safety. In this study, a disposable biosensor with two individual sensing channels is prepared on an affordable cellulose paper substrate and used to simultaneously detect fumatoxin B1 (FB1) and aflatoxin B1 (AFB1). The biosensor pattern is outlined by polydimethylsiloxane (PDMS) and the hydrophobic interface of the sensing channels is created using octadecyltrichlorosilane (OTS). Semiconducting single‐wall carbon nanotubes (s‐SWCNTs) are deposited onto the central zones to serve as the sensing elements and SWCNTs are deposited into the bilateral areas as wire. After functionalization of the s‐SWCNTs, anti‐FB1 and anti‐AFB1 are separately immobilized on the different sensing regions to capture the targeted mycotoxins. Under the optimal conditions, this developed s‐SWCNTs‐based biosensor array achieved a limit of detection (LOD) of 8.23 pg mL−1 for FB1 and 7.48 pg mL−1 for AFB1. As a demonstration, spiked corn samples are measured using this biosensor and recovery rates are not inferior to commercial enzyme‐linked immune sorbent assay (ELISA) kits. Overall, the cost‐effective, highly sensitive, and multiplexed biosensor platform fabricated by this approach shows great potential for detecting multiple mycotoxins. [ABSTRACT FROM AUTHOR]

2D materials are highly regarded for their exceptional sensing application prospects, stemming from their distinctive atomic layer structure and exceptionally sensitive surfaces. Over the past decade, numerous high‐performance 2D material sensors are extensively developed; however, challenges related to sensitivity, selectivity, and stability continue to impede their industrial advancement. The interaction between light and 2D materials has introduced unique properties, including absorption and emission characteristics, photoelectric effects, nonlinear optical effects, surface‐enhanced Raman scattering, and light response enhancement. Consequently, exciting and adjusting the electronic structure and carrier concentration of 2D materials through light with specific wavelength ranges is an effective strategy for enhancing sensing performance. This strategy has yielded remarkable breakthroughs in applications such as photodetectors, semiconductor gas sensors, and fiber optic sensors. Moreover, it demonstrates extraordinary potential in emerging applications such as image sensors, flexible electronics, and biomedical sensors. However, the sensing mechanism, device structure design, and specific applications of 2D materials under light excitation remain unclear. This perspective endeavors to elucidate the intrinsic photophysical mechanisms between light‐excited 2D materials and their target sensing analytes. Furthermore, it aims to explain the evolutionary pattern of sensing applications and provide novel insights and inspiration to advance this burgeoning field. [ABSTRACT FROM AUTHOR]

An innovative photocatalytic fuel cell (PFC)-based self-powered system was developed by integrating the perovskite Ag3BiO3/Ti3C2 MXene plasmonic heterojunction with a self-breathing strategy, which was beneficial for developing high-performance self-powered photoelectrochemical biosensors. [ABSTRACT FROM AUTHOR]

As a representative gas of food spoilage, the development of rapid hydrogen sulfide (H2S) analysis strategies for food safety control is in great demand. Despite traditional methods for H2S detection possessing great achievements, they are still incapable of meeting the requirement of portability and quantitative detection at the same time. Herein, a nanozyme catalysis pressure-powered sensing platform that enables visual quantification with the naked eye is proposed. In this methodology, Pt nanozyme inherits the catalase-like activity to facilitate the decomposition of H2O2 to O2, which can significantly improve the pressure in the closed container, further pushing the movement of indicator dye. Furthermore, H2S was found to effectively inhibit the catalytic activity of Pt nanozyme, indicating that the catalase-like activity of PtNPs may be regulated by varying concentrations of H2S. Therefore, by utilizing a self-designed pressure-powered microchannel device, the concentration of H2S was successfully converted into a distinct signal variation in distance. The effectiveness of the as-designed sensor in assessing the spoilage of red wine by H2S determination has been demonstrated. It exhibits a strong correlation between the change in dye distance and H2S concentration within the range of 1–250 μM, with a detection limit of 0.17 μM. This method is advantageous as it enhances the quantitative detection of H2S with the naked eye based on the portable pressure-powered sensing platform, as compared to traditional H2S biosensors. Such a pressure-powered distance variation platform would greatly broaden the application of H2S-based detection in food spoilage management. [ABSTRACT FROM AUTHOR]

In this review, the forefront of biosensor development has been marked by a profound exploration of carbon nanostructured materials for the specific application of glucose detection. Moreover, this progressive line of inquiry capitalizes on the distinctive attributes of carbon nanostructured materials such as carbon nanotubes, carbon quantum dots, and graphene which exhibit unique characteristics in the development of biosensor engineering design. It also enhanced analytical performances regarding the limit of detection, selectivity, sensitivity, and reproducibility towards glucose detection in biological samples. Most importantly, the strategic integration of carbon nanostructured-based biosensor architectures has played a significant role in advancements, characterized by heightened sensitivity, exquisite selectivity, and augmented stability in glucose detection processes. Furthermore, utilizing these advanced materials has engendered a transformative impact on electrochemical properties, propelling the biosensors to achieve rapid and precise glucose-sensing capabilities. The confluence of carbon nanostructures with biosensor technology has not only elevated the scientific understanding of glucose detection mechanisms. Still, it has also paved the way for miniaturized and portable biosensors. This transformative shift holds great promise for the realization of point-of-care diagnostics, representing a pivotal step towards durability and efficient glucose monitoring in health/medical care. These advancements emphasize the crucial role of carbon nanostructured-based biosensors in opening the way to a new avenue of superiority and effectiveness in diabetes management. Conclusively, the challenges and, in a forward-looking stance, the prospective futures of glucose biosensors anchored on carbon nanostructured frameworks were considered. [ABSTRACT FROM AUTHOR]

The interactions of dendrimers having a phosphorus atom at each branching point, of type poly(phosphorhydrazone) (PPH), with different types of materials based on silicon and aluminum are reviewed. These dendrimers can be used for the functionalization of solid surfaces at the nanoscale, either by covalent immobilization, or by electrostatic interactions, especially for constructing perfectly controlled multi‐layers by layer‐by‐layer (LbL) deposit. The properties of such hybrid materials as chemical sensors, as very sensitive biological sensors, as well as substrates for the growing of cells are described. The PPH dendrimers can also be embedded inside materials. The resulting hybrid materials have been used for the capture of pollutants, in particular CO2 in air and chromate and methylene blue in waste water. [ABSTRACT FROM AUTHOR]

Optical bound states in the continuum (BICs) lies in side the continuum and coexists with extended waves, but it remains perfectly confined without any radiation. This unique property of BICs has led to numerous applications, such as highly surface‐sensitive and spectrally sharp resonances for photonic biosensors. However, it remains challenging to experimentally realize the BICs in a single‐particle system, especially for subwavelength structures. This study presents the existence of optical BICs in a subwavelength metallic microstructure, and quasi‐BICs are observed experimentally in a waveguide system with only a single optimized aluminum meta‐particle. This plasmonic BICs is resulting from the destructive interference of two localized surface plasmon modes. Benefiting from its strong localized field confinement and substrate‐free merit of BICs, the experimentally measured quality factor (Q‐factor) of this transmission dip reach to 273. Additionally, this meta‐particle is experimentally verified to show a good sensitivity for both solids and liquids through the spectral shift of the BICs caused transmission dip. This finding extends the optical BICs to a subwavelength scale and opens practical application opportunities for ultrasmall‐quantity detection of biochemical substances. [ABSTRACT FROM AUTHOR]

Background: Chronic wasting disease (CWD) is a fatal transmissible spongiform encephalopathy in cervids. The disease is caused by a pathogenic prion, namely PrPSc. Currently, diagnosis of CWD relies on IHC detection of PrPSc in the obex or retropharyngeal lymph nodes (RPLN) or ELISA screening of obex and RPLN followed by IHC confirmation of positive results. In this study, we assessed the performance characteristics of two immunoassays: CWD Ag-ELISA and TeSeE ELISA, RT-QuIC, and MEMS biosensor via testing 30 CWD + and 30 CWD- white-tailed deer RPLN samples. Results: Both CWD Ag-ELISA and TeSeE ELISA correctly identified all CWD + and CWD- samples. A greater intra-assay coefficient of variation (CV) in S/P ratios was observed for the TeSeE ELISA (16.52%), compared to CWD Ag-ELISA (9.49%). However, the high CV did not affect the qualitative results of triplicate assays when the corresponding manufacturer's cutoff was used. The MEMS biosensor not only correctly identified all CWD + and CWD- RPLN samples, but also demonstrated a 100% detection rate for all CWD + samples at dilutions from 10− 0 to 10− 3. Evaluation of RT-QuIC indicated that the rate of false negative reactions decreased from 21.98% at 10− 2 dilution to 0% at 10− 4 and 10− 5 dilutions; and the rate of false positive reactions reduced from 56.42% at 10− 2 dilution to 8.89% and 2.22% at 10− 4 and 10− 5 dilutions, respectively. Based on a stringent threshold of 2 x the first 10 fluorescent readings of each well and a final cutoff of 2/3 positive reactions for each sample, RT-QuIC correctly identified all positive and negative samples at 10− 4 and 10− 5 dilutions. Both MEMS biosensor and RT-QuIC achieved 100% sensitivity and 100% specificity under the experimental conditions described in this study. Conclusions: The two immunoassays (CWD Ag-ELISA and TeSeE ELISA) performed comparably on white-tailed deer RPLN samples. MEMS biosensor is a reliable portable tool for CWD diagnosis and RT-QuIC can be used for routine testing of CWD if appropriate testing parameters and interpretive criteria are applied. [ABSTRACT FROM AUTHOR]

In this paper, a novel realization of an ink-on-glass microwave sensor for biomedical applications is proposed. The Aerosol Jet Printing (AJP) technology is leveraged to implement a compact single-layer coplanar waveguide sensor featuring arc-shaped interdigital fingers that can accommodate a droplet of the Material-Under-Test (MUT). Such geometry provides a high sensitivity to even a very small deviation of MUT's electrical properties when placed as a superstrate. An application towards the detection of trace amounts of glucose in saliva, which is a biomarker for diabetes, is showcased. The design and fabrication process of an exemplary sensor is discussed in detail. A circular geometry feature is introduced that helps a droplet to lie over the sensitive region due to wettability difference of glass substrate and silver ink. Sensor operating in K-band is developed providing a tradeoff between circuit size and droplet volume. The study is conducted for an artificial saliva requiring roughly a 0.5 µL droplet where changes in mixture content are proportional to relative changes of sensor's transmission coefficient in a broad frequency range for occupied vs. empty states. The obtained results show that 10 mg of glucose per 100 ml of saliva can be easily distinguished in a frequency range of 20–30 GHz, whereas a monotonical change is visible for frequencies 20–26 GHz, which indicates the applicability of this sensor towards the detection of saliva-glucose levels and potential application in the detection of small amounts of other substances in liquids. [ABSTRACT FROM AUTHOR]

As a critical metabolite, the standardization of lactate quantification is increasingly crucial. Therefore, we developed LaconicSF, a lactate-responsive biosensor exhibiting exceptional specificity in lactate detection. LaconicSF enables efficient lactate quantification in CHO cell culture medium and holds potential as a user-friendly detection tool for lactate quantification in vitro. [ABSTRACT FROM AUTHOR]

In this work, we reported an electrochemical biosensor with target-assisted self-cleavage DNAzyme function for signal amplified detection of miRNA. The target-recycling amplification led to significant signal enhancement and thus offers high detection sensitivity. [ABSTRACT FROM AUTHOR]

This work proposed an easy-to-perform but effective strategy to eliminate the ACQ effect of PAHs for ECL enhancement by coordinatively grafting PAH-derived ligands onto ultrathin MOLs, which opened a new horizon to develop high-efficiency Ru-complex-free porous ECL materials for fabricating supersensitive ECL sensing platforms. [Display omitted] • A novel ECL emitter was prepared by coordinatively grafting a new ECL luminophore PyTS on ultrathin MOL. • This work proposed a new and facile strategy to surmount the ACQ effect of PAHs. • This strategy provided significant inspiration for designing high-efficiency Ru-complex-free ECL materials. • The fabricated ECL biosensor accomplished the supersensitive detection of miRNA-21. The exploration of novel electrochemiluminescence (ECL) luminophores with excellent ECL properties is a current research hotspot in the ECL field. Herein, a novel high-efficiency Ru-complex-free ECL emitter PyTS-Zr-BTB-MOL has been prepared by using porous ultrathin Zr-BTB metal–organic layer (MOL) as carrier to coordinatively graft the cheap and easily available polycyclic aromatic hydrocarbon (PAH) derivative luminophore PyTS whose ECL performance has never been investigated. Gratifyingly, the ECL intensity and efficiency of PyTS-Zr-BTB-MOL were markedly enhanced compared to both PyTS monomers and PyTS aggregates. The main reason was that the distance between pyrene rings was greatly expanded after the PyTS grafting on the Zr 6 clusters of Zr-BTB-MOL, which overcame the aggregation-caused quenching (ACQ) effect of PyTS and thus enhanced the ECL emission. Meanwhile, the porous nanosheet structure of PyTS-Zr-BTB-MOL could distinctly increase the exposure of PyTS luminophores and shorten the diffusion paths of coreactants and electrons/ions, which effectively promoted the electrochemical excitation of more PyTS luminophores and thus achieved a further ECL enhancement. In light of the remarkable ECL property of PyTS-Zr-BTB-MOL, it was employed as an ECL indicator to build a novel high-sensitivity ECL biosensor for microRNA-21 determination, possessing a satisfactory response range (100 aM to 100 pM) and an ultralow detection limit (10.4 aM). Overall, this work demonstrated that using MOLs to coordinatively graft the PAH derivative luminophores to eliminate the ACQ effect and increase the utilization rate of the luminophores is a promising and efficient strategy to develop high-performance Ru-complex-free ECL materials for assembling ultrasensitive ECL biosensing platforms. [ABSTRACT FROM AUTHOR]

Voltage-responsive biosensors capable of monitoring real-time adsorption behavior of biological analytes onto electroactive surfaces offer attractive strategies for disease detection, separations, and other adsorption-dependent analytical techniques. Adsorption of biological analytes onto electrically switchable surfaces can be modelled using neutravidin and biotin. Here, we report self-assembled monolayers formed from voltage-switchable biotinylated molecules on gold surfaces with tunable sensitivity to neutravidin in response to applied voltages. By using electrochemical quartz crystal microbalance (EQCM), we demonstrated real-time switchable behavior of these bio-surfaces and investigate the range of sensitivity by varying the potential of the same surfaces from −400 mV to open circuit potential (+155 mV) to +300 mV. We compared the tunability of the mixed surfaces to bare Au surfaces, voltage inert surfaces, and switchable biotinylated surfaces. Our results indicate that quartz crystal microbalance allows real-time changes in analyte binding behavior, which enabled observing the evolution of neutravidin sensitivity as the applied voltage was shifted. EQCM could in principle be used in kinetic studies or to optimize voltage-switchable surfaces in adsorption-based diagnostics. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Food Safety & Quality is the property of Journal of Food Safety & Quality Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Enzymes play a significant role in mediating inflammatory and immune responses in periodontitis. Effective diagnosis, timely treatment, and continuous management of periodontal enzymes are essential to prevent undesirable consequences; however, this remains a significant challenge. Nanoparticles (NPs) have attracted significant attention in biomedicine because of their advantageous nanosized effects. NPs are conjugated with specific enzyme substrates at responsive sites that are triggered by periodontitis enzyme biomarkers, leading to functional or characteristic changes. In contrast, NPs with enzyme-mimetic activities exhibit catalytic activity, effectively destroying pathogenic biofilms and modulating the immune response in periodontitis. The unique properties of enzyme-targeting NPs have enabled the development of biosensors and fluorescent probes capable of identifying enzyme biomarkers associated with periodontitis. Enzyme-responsive and enzyme-mimetic NPs both exert therapeutic applications in the treatment of periodontitis. In this review, we provide a comprehensive overview of the enzymes associated with periodontitis, the mechanisms of enzyme-responsive and enzyme-mimetic NPs, recent advancements in the use of NPs for detecting these enzymes, and the therapeutic applications of NPs in targeting or mimicking enzyme functions. We also discuss the challenges and prospects of using NPs in the diagnosis and treatment of periodontitis. [ABSTRACT FROM AUTHOR]

This study investigates the sensitivity of Underlap Gate Cavity-based Reconfigurable Silicon Nanowire Schottky Barrier Transistor (UCG-RSiNW SBT) with an underlap gate-drain region for biosensing application. The featured unique reconfigurable capability enables the device to operate as either p-type or n-type, dependent on the applied bias polarity. The proposed biosensor incorporates a cavity beneath the control gate on the source side, facilitating the placement of both neutral and charged biomolecules with varying dielectric constant (K) values. Upon injection of biomolecules into the cavity, the device changes electrostatic characteristics, including modulation in threshold voltage, potential, electric field, and sub-threshold swing, I ON , I ON / I OFF ratio. The threshold voltage ( V TH ) Sensitivity of n-mode is enhanced by 97.91 % , while that of p-mode is raised by 16 % compared to conventional RFET biosensors. The drain current sensitivity and the linearity of proposed biosensor is enhanced upto the values of 2792 and 0.997 respectively in n-mode configuration whereas in p-mode configuration, the drain current sensitivity and the linearity comes out to be 968 and 0.995 respectively. These high sensitivity and linearity values make this biosensor superior to the existing state-of-the-art biosensors. The findings from this study provide valuable insights into the development of highly sensitive biosensors for applications in diverse fields, including healthcare and biotechnology. [ABSTRACT FROM AUTHOR]

Membrane contact sites (MCSs) are hubs allowing various cell organelles to coordinate their activities. The dynamic nature of these sites and their small size hinder analysis by current imaging techniques. To overcome these limitations, we here design a series of reversible chemogenetic reporters incorporating improved, low-affinity variants of splitFAST, and study the dynamics of different MCSs at high spatiotemporal resolution, both in vitro and in vivo. We demonstrate that these versatile reporters suit different experimental setups well, allowing one to address challenging biological questions. Using these probes, we identify a pathway in which calcium (Ca2+) signalling dynamically regulates endoplasmic reticulum-mitochondria juxtaposition, characterizing the underlying mechanism. Finally, by integrating Ca2+-sensing capabilities into the splitFAST technology, we introduce PRINCESS (PRobe for INterorganelle Ca2+-Exchange Sites based on SplitFAST), a class of reporters to simultaneously detect MCSs and measure the associated Ca2+ dynamics using a single biosensor. Studying membrane contact sites at high spatiotemporal resolution is still challenging. Here, authors introduce a series of dynamic chemogenetic reporters to visualize these subcellular regions and study the associated calcium signals. [ABSTRACT FROM AUTHOR]

Mammalian odorant binding proteins (OBPs) have long been suggested to transport hydrophobic odorant molecules through the aqueous environment of the nasal mucus. While the function of OBPs as odorant transporters is supported by their hydrophobic beta‐barrel structure, no rationale has been provided on why and how these proteins facilitate the uptake of odorants from the gas phase. Here, a multi‐scale computational approach validated through available high‐resolution spectroscopy experiments reveals that the conformational space explored by carvone inside the binding cavity of porcine OBP (pOBP) is much closer to the gas than the aqueous phase, and that pOBP effectively manages to transport odorants by lowering the free energy barrier of odorant uptake. Understanding such perireceptor events is crucial to fully unravel the molecular processes underlying the olfactory sense and move towards the development of protein‐based biomimetic sensor units that can serve as artificial noses. [ABSTRACT FROM AUTHOR]

Since 1990, numerous aptamers have been isolated and discovered for use in various analytical, biomedical, and environmental applications. This trend continues to date. A critical step in the characterization of aptamer binding is to measure its binding affinity toward both target and non‐target molecules. Dissociation constant (Kd) is the most commonly used value in characterizing aptamer binding. In this article, homogenous assays are reviewed for aptamers that can bind small‐molecule targets. The reviewed methods include label‐free methods, such as isothermal titration calorimetry, intrinsic fluorescence of target molecules, DNA staining dyes, and nuclease digestion assays, and labeled methods, such as the strand displacement reaction. Some methods are not recommended, such as those based on the aggregation of gold nanoparticles and the desorption of fluorophore‐labeled DNA from nanomaterials. The difference between the measured apparent Kd and the true Kd of aptamer binding is stressed. In addition, avoiding the titration regime and paying attention to the time required to reach equilibrium are discussed. Finally, it is important to include mutated non‐binding sequences as controls. [ABSTRACT FROM AUTHOR]

In this study, we examined the photophysical properties of an azacrown–iridium(III) complex while focusing on its interactions with calcium ions (Ca2+). We explored the dynamic processes within the complex combining time-dependent density functional theory (TDDFT) calculations and time-resolved spectroscopies. In the presence of Ca2+, the complex exhibits significant shifts in absorption and emission profiles, from 494 nm to 375 nm, aligning with theoretical predictions. Notably, we observed the ultrafast photo-ejection of Ca2+ within 70 femtoseconds, followed by its recapture in 250 nanoseconds, revealing a 10-million-fold timescale difference between the two phenomena. These behaviors confirm the established photophysical properties of polypyridyl iridium(III) complexes and their intrinsic sensitivity to their surrounding environment. Our comprehensive kinetic analysis highlights the azacrown moiety's competitive binding and photo-release capabilities, suggesting its potential for practical sensing applications. The versatile properties of these iridium(III) complexes offer promising prospects for their application as stimuli-responsive materials and in advanced optoelectronic devices, targeted imaging, and biomedical ion sensors and delivery systems. [ABSTRACT FROM AUTHOR]