Signal Readout Research Articles

Diagnostic Assays Enabled by Engineered Nanoparticles.

Nanoparticles have broad applications in medical diagnosis, bioengineering, and various other domains. Engineered nanoparticles are pivotal in enhancing in vitro detection performance. Utilizing signal readouts such as bioluminescence, fluorescence, and others, nanoparticles enable precise, real-time monitoring of a wide range of analytes. Furthermore, nanoparticles are ingeniously designed to improve the efficiency of in vivo imaging. Nanoparticles are integral to both deep-body imaging, which utilizes advanced techniques such as magnetic resonance imaging or computed tomography (CT), and high-resolution, real-time optical imaging, which are essential for applications such as fluorescence-guided surgery. Here, we highlight these impactful diagnostic assays enabled by engineered nanoparticles, comparing their advantages and disadvantages extensively. For the introduction of each method, we compare the most classic and latest research as much as possible to provide a comprehensive perspective. Finally, we summarize the current limitations and challenges of nanoparticles for diagnostic analysis while also exploring future trends and prospects.

Metal Ion-Based Chemical Coordination Amplification: A Chromophore In Situ Deposition Strategy for Visual Sensitivity-Enhanced Lateral Flow Immunochromatography Assays.

Traditional lateral flow immunochromatography assays (LFIAs) have faced low sensitivity for trace detection due to the lack of colorimetric brightness. The current strategies to improve sensitivity commonly have the disadvantages of an uncontrollable enhancement process or high background interference, leading to huge obstacles for signal readout. Herein, an in situ metal ion-based chemical coordination amplification (MICCA) strategy has been reported. Metal ion clusters on metal-organic frameworks could coordinate with chromophores to produce colored complexes for visual signal enhancement. A Zr-based metal AIEgen framework (MAF) loaded with Prussian blue was chosen as the dual-mode signal tag for colorimetric and fluorescent readout. MAF could be employed as a grafting substrate to in situ deposit chromophores through the coordination with Zr4+ clusters and arsenazo III. The process of MICCA was in situ, controllable, and free of background interference. For target cancer biomarker alpha-fetoprotein (AFP), the limit of detection (LOD) by the naked eye was 25 ng/mL, and the LODs of MICCA and fluorescence were 5 ng/mL, which was 5-fold decreased. Significantly, MICCA-LFIA could effectively differentiate between AFP-positive and AFP-negative clinical serum samples. The quantitative results were highly consistent with clinical results (R2 = 0.9927). This work explored the application of metal ion-based chemical coordination reactions in signal amplification strategies and provided ideas for high-sensitivity LFIA development.

DNAzyme-Triggered Equilibrium Transfer with Self-Activated CRISPR-Cas12a Biosensor Enables One-Pot Diagnosis of Nucleic Acids.

Integrating recombinase-polymerase amplification (RPA) with CRISPR-Cas12a holds significant potential to simplify and improve nucleic acid diagnostic procedures. However, current strategies face limitations, such as complexity, reduced efficiency, and potential compromises in Cas12a activity. In response, we developed a DNAzyme-triggered equilibrium transfer with a self-activated CRISPR-Cas12a biosensor (DESCRIBER) for integrated nucleic acid detection. This platform features varying balance points to minimize interference between RPA and Cas12a in one pot and maximize their activity at different stages. Initially, the reaction focused on RPA, while Cas12a was silenced by circular-crRNA (C-crRNA). Then, DNAzyme, the activator, was generated during the RPA process, which linearizes C-crRNA to activate Cas12a and transfer the equilibrium toward signal readout. Meanwhile, activated Cas12a can further linearize C-crRNA to promote self-activation and accelerate equilibrium transfer. According to this principle, highly sensitive detection of the HIV-1 genome, as low as 500 CPs/mL, was achieved within 1 h while maintaining universality in detecting common subtypes and specificity against opportunistic infectious pathogens. Compared with qRT-PCR, it also exhibited good accuracy in detecting 35 spiked samples. Overall, we believe that the proposed strategy will enhance existing CRISPR systems to promote their practical applications in clinical diagnosis.

Progesterone induces meiosis through two obligate co-receptors with PLA2 activity

The steroid hormone progesterone (P4) regulates multiple aspects of reproductive and metabolic physiology. Classical P4 signaling operates through nuclear receptors that regulate transcription. In addition, P4 signals through membrane P4 receptors (mPRs) in a rapid nongenomic modality. Despite the established physiological importance of P4 nongenomic signaling, the details of its signal transduction cascade remain elusive. Here, using Xenopus oocyte maturation as a well-established physiological readout of nongenomic P4 signaling, we identify the lipid hydrolase ABHD2 (α/β hydrolase domain-containing protein 2) as an essential mPRβ co-receptor to trigger meiosis. We show using functional assays coupled to unbiased and targeted cell-based lipidomics that ABHD2 possesses a phospholipase A2 (PLA2) activity that requires mPRβ. This PLA2 activity bifurcates P4 signaling by inducing clathrin-dependent endocytosis of mPRβ, resulting in the production of lipid messengers that are G-protein coupled receptor agonists. Therefore, P4 drives meiosis by inducing an ABHD2 PLA2 activity that requires both mPRβ and ABHD2 as obligate co-receptors.

Progesterone induces meiosis through two obligate co-receptors with PLA2 activity.

The steroid hormone progesterone (P4) regulates multiple aspects of reproductive and metabolic physiology. Classical P4 signaling operates through nuclear receptors that regulate transcription. In addition, P4 signals through membrane P4 receptors (mPRs) in a rapid nongenomic modality. Despite the established physiological importance of P4 nongenomic signaling, the details of its signal transduction cascade remain elusive. Here, using Xenopus oocyte maturation as a well-established physiological readout of nongenomic P4 signaling, we identify the lipid hydrolase ABHD2 (α/β hydrolase domain-containing protein 2) as an essential mPRβ co-receptor to trigger meiosis. We show using functional assays coupled to unbiased and targeted cell-based lipidomics that ABHD2 possesses a phospholipase A2 (PLA2) activity that requires mPRβ. This PLA2 activity bifurcates P4 signaling by inducing clathrin-dependent endocytosis of mPRβ, resulting in the production of lipid messengers that are G-protein coupled receptor agonists. Therefore, P4 drives meiosis by inducing an ABHD2 PLA2 activity that requires both mPRβ and ABHD2 as obligate co-receptors.

Microfluidic-Enabled Self-Directed Hydrogel Microspheres for Multiplexed MicroRNA Assays.

Multiplexed microRNA (miRNA) detection has proven valuable in disease diagnosis; yet, the development of advanced tools for their analysis remains a subject of broad interest. Here, we propose a novel single-particle method for multiplexed miRNA detection using self-directed hydrogel microspheres, which feature supersegmented compartments for loading analyte probes and an air-encapsulated region that grants the microsphere a unique preferred posture in aqueous solutions. By exploiting microfluidic technology, we can widely adjust the size of the microspheres and the number of compartments can be widely adjusted. The air-encapsulated region is located at the edge of the microsphere's symmetry axis, resulting in a spontaneous orientation that facilitates efficient multitarget signal readout in a standard manner without requiring active energy input. The microspheres exhibit excellent temperature stability, ensuring consistent performance under varying thermal conditions. Additionally, signal amplification strategies, such as hybridization chain reaction, are compatible with microspheres, enabling sensitive miRNA quantification. As a concept of proof, precise miRNA detection was demonstrated using these features. We hope that the proposed biocompatible microsphere tools will find broader application prospects in various clinical diagnostic settings.

A Fully Integrated ICP-Enriched and Nanozyme-Catalyzed Lateral Flow Assay for cfDNA Detection in Whole Blood.

Rapid and sensitive detection of Epstein-Barr virus cell-free DNA (EBV cfDNA) is crucial for early diagnosis and monitoring of nasopharyngeal carcinoma (NPC), but accessibility to screening is limited by complicated and costly conventional DNA isolation and purification approaches. Here, a fully integrated ion concentration polarization (ICP)-enriched and nanozyme-catalyzed lateral flow assay (ICP-cLFA) is developed, enabling total analysis of EBV cfDNA in whole blood samples, with DNA isolation, pre-concentration, and amplification performed on a microfluidic chip, consequently providing the signal readout within 75 min. Specifically, ICP preconcentration and amplification steps, together with target recognition catalyzed by a platinum-decorated mesoporous gold nanosphere (MGNS@Pt) nanozyme, result in an ultralow detection limit of 4 aM in standard cfDNA samples and 100 aM in whole blood from NPC-bearing rats. The high sensitivity and specificity of the ICP-cLFA suggest strong potential for cfDNA screening in resource-limited clinical and field applications.

Smart Polymeric 3D Microscaffolds Hosting Spheroids for Neuronal Research via Quantum Metrology.

Toward the aim of reducing animal testing, innovative in vitro models are required. Here, this study proposes a novel smart polymeric microscaffold to establish an advanced 3D model of dopaminergic neurons. These scaffolds are fabricated with Ormocomp via Two-Photon Polymerization. The scaffolds are further enhanced by functionalization with fluorescent nanodiamonds (FNDs), which can serve as quantum nanosensors for both magnetic and temperature sensing.The material biocompatibility is tested using two different cell lines, SH-SY5Y and A431, with cell viability over 98%. A total of 69% of the FNDs are grafted on the structure compared to those that remained on the glass surface. Cells are tested with the scaffolds in several microenvironments, and the final assembly required for 3D quantum metrology experiments achieved 91% biocompatibility. Subsequently, embryoid bodies containing dopaminergic neurons, the cell type affected by Parkinson's disease (PD), are integrated with FND-functionalized scaffolds. This 3D model is successfully established, demonstrated by strong interactions between dopaminergic neurons and the scaffold, with the directional growth of neurites along the 3D scaffold. Ultimately, this study have developed a 3D platform that enables the readout of signaling in a model that holds great potential for future PD research.

A POCT assay based on commercial HCG strip for miRNA21 detection by integrating with RCA-HCR cascade amplification and CRISPR/Cas12a.

Apoint-of-care testing (POCT) assay based on commercial HCG strip was proposed for miRNA21 detection by integrating RCA-HCR cascaded isothermal amplification with CRISPR/Cas12a. Three modules were integrated in the proposed platform: target amplification module composed of rolling circle amplification (RCA) cascaded with hybridization chain reaction (HCR), signal transduction module composed of CRISPR/Cas12a combined with HCG-agarose gel beads probes, and signal readout module composed of commercial HCG strips. The proposed RCA-HCR-CRISPR/Cas12a-HCG strip assay for miRNA21 detection had high sensitivity, and the limit of detection was as low as 37 fM. The proposed assay showed excellent specificity for miRNA21, as other miRNAs did not caused interference for detection. The recoveries of miRNA21 were ranged from 89.0 to 118.0%. The intra-batch and inter-batch coefficient of variation (CV) were 10.1-13.4% and 11.9-14.5%, respectively, which indicated ahigh accuracy and precision, and the serum matrix did not cause any interference. With the advantages of low-cost, high sensitivity, visualization, and easy popularization, the proposed assay is expected to provide a powerful tool for early diagnosis of tumor disease miRNA, especially in resource-limited areas.

Harnessing individual nitrogen-vacancy centers with a compact and portable confocal microscope

Abstract Recent advancements in quantum technology have highlighted the potential of nitrogen-vacancy (NV) centers in diamond. However, fully realizing this potential requires addressing challenges related to the size, complexity, and cost of current optical systems used for NV center manipulation. In this work, we present a compact and portable confocal setup specifically designed for the efficient detection and control of single NV centers. Our system facilitates optical initialization and readout of individual NV center photoluminescence signals, enabling coherent spin control and nanoscale-resolution magnetic field sensing.

Development of a Semiquantitative Barcode Readout Approach for Paper-Based Analytical Devices (PADs) for Enzymatic H2O2 and Glucose Detection.

The integration of barcode technology with smartphones on paper-based analytical devices (PADs) presents a promising approach to bridging manual detection with digital interpretation and data storage. However, previous studies of 1D barcode approaches have been limited to providing only a "yes/no" response for analyte detection. Herein, a method of using barcode readout for semiquantitative signal detection on PADs has been achieved through the integration of barcode technology with a distance-based measurement concept on PADs. To demonstrate the feasibility of this concept, a PAD fabrication strategy incorporating barcodes was explored, using the enzymatic reaction between horseradish peroxidase (HRP), 3,3'-diaminobenzidine (DAB), and H2O2 as a model system. The enzyme-catalyzed polymerization of DAB to polyDAB in the presence of hydrogen peroxide results in the appearance of color observable by the naked eye inside a paperfluidic channel, with the color-changed length depending on the H2O2 concentration. At the same time, the barcode pattern displayed as a result of this distance-based color evolution overlaid with a paper-based barcode layer can be read using a smartphone application. Parameters affecting the signal readout performance were studied. The developed device can be used to detect H2O2 concentrations in the range of 0.25 to 10 mM within 90 min with 79.6% of barcode signals correctly readable. Additionally, results from different smartphone models showed a consistent reading performance (78.4-79.6%). Finally, the quantification of glucose levels in artificial urine samples was demonstrated. This developed PAD signaling strategy offers end-users more simplicity and can be used as a standalone device or in conjunction with other digital devices.

Toward At-Home and Wearable Monitoring of Female Hormones: Emerging Nanotechnologies and Clinical Prospects.

Steroid hormones, especially progesterone (P4), estradiol (E2), and testosterone (T), are key bioactive regulators in various female physiological processes, including growth and development, ovulation, and the reproductive cycle, as well as metabolism and mental health. As lipophilic molecules produced in sex glands, these steroid female hormones can be transported through blood vessels into various body fluids such as saliva, sweat, and urine. However, the ultralow concentration of steroid hormones down to picomolar (pM) level necessitates great demands for ultrasensitive but low-cost analytic tools to implement accurate, point-of-care or even continuous monitoring in a user-friendly fashion. This review focuses on the latest advances in materials and nanotechnologies to allow the rapid detection of female hormones at the pM level or below and the potentials in at-home and wearable hormone monitoring. We specifically summarize the optical and electrochemical strategies in this category, particularly those affording low cost and portable signal readout for at-home use. Furthermore, emerging flexible/wearable innovations are highlighted, which allow the continuous hormone cycle tracking in a noninvasive manner. The potential of these techniques is discussed to address the need for real-time acquisition of the hormone fluctuation, facilitating health monitoring at home. Lastly, we provide a comprehensive introduction to the prospects of female hormone monitoring in clinical diagnosis and treatment, from the perspective of gynecology and reproductive medicine clinicians.

Micropore Resistance Counting Platform for Multiplexed and Ultrasensitive Detection of Mycotoxins and Biomarkers.

Development of a multiplexed and sensitive biosensing platform is a priority for public health security. We report a micropore resistance counting platform based on polystyrene microsphere size-based encoding and Clostridium butyricum Argonaute (CbAgo) decoding for multiplexed and ultrasensitive detection. Initially, we constructed a target DNA-modified polystyrene microsphere coding system based on micropore resistance counting. Subsequently, the precise recognition and cleavage capabilities of the guide DNA-activated CbAgo protein enable the decoding of the encoded microsphere system. Changes in the concentration of polystyrene microspheres are presented as a signal readout. The platform demonstrated excellent performance in multiplexed detection of three mycotoxins (with a sensitivity range over 4 orders of magnitude reaching the pg/mL level) and two inflammatory markers at pg/mL. Combining precise enzyme cleavage by CbAgo with micropore resistance counting, the developed platform is a multiplexed and highly sensitive detection tool with wide-ranging potential in applications such as clinical diagnosis, food safety inspection, and environmental monitoring.

Portable pH meter-based competitive immunoassay of E-selectin using urease-encapsulated metal-organic frameworks.

E-selectin (CD62E) is an adhesion molecule expressed on the surface of endothelial cells (ECs) and its level increases significantly upon the stimulation of ECs by inflammatory factors. Quantitative analysis of CD62E is of great importance to early diagnosis and treatment of vascular diseases and hypertension. A new method for the determination of CD62E was developed using a portable pH meter in this work. Two nanocomposites, urease-encapsulated and CD62E antibody-linked zeolitic imidazolate framework-8 (U@ZIF-8-Ab) and CD62E protein-coated Fe3O4 magnetic beads (MB-CD62E), were prepared successfully. MOF shells of U@ZIF-8-Ab provided an effective protection against inactivation for urease. The reaction product of two nanocomposites, which was collected via magnetic separation, catalyzed the hydrolysis of urea and led to the increase in pH of the substrate solution. CD62E could competitively react with U@ZIF-8-Ab, inhibiting the binding of two nanocompoaites. Due to the reduction of urease in the magnetically separated product, the hydrolysis of urea was limited and the pH increasing extent declined. The pH difference was found to be linearly related to the logarithm of the CD62E concentration from 0.02 to 500ngmL-1 with a detection limit of 9.28pgmL-1. The developed method displayed some advantages, such as good selectivity, reproducibility and stability, low-dose reagents, and simple measurement procedure. This work provides a valuable sample for immunoassay and biosensing using enzyme-encapsulated metal-organic frameworks and portable pH meter as signal readout.

Carbon Dots-Modified Hollow Mesoporous Photonic Crystal Materials for Sensitivity- and Selectivity-Enhanced Sensing of Chloroform Vapor

Chloroform and other volatile organic pollutants have garnered widespread attention from the public and researchers, because of their potential harm to the respiratory system, nervous system, skin, and eyes. However, research on chloroform vapor sensing is still in its early stages, primarily due to the lack of specific recognition motif. Here we report a mesoporous photonic crystal sensor incorporating carbon dots-based nanoreceptor (HMSS@CDs-PCs) for enhanced chloroform sensing. The colloidal PC packed with hollow mesoporous silica spheres provides an interconnected ordered macro-meso-hierarchical porous structure, ideal for rapid gas sensing utilizing the photonic bandgap shift as the readout signal. The as-synthesized CDs with pyridinic-N-oxide functional groups adsorbed in the hollow mesoporous silica spheres are found to not only serve as the chloroform adsorption sites, but also a molecular glue that prevents crack formation in the colloidal PC. The sensitivity of HMSS@CDs-PCs sensor is 0.79 nmppm-1 and an impressively low limit of detection is 3.22ppm, which are the best reported values in fast-response chloroform vapor sensor without multi-signal assistance. The positive response time is 7.5s and the negative response time 9s. Furthermore, relatively stable sensing can be maintained within a relative humidity of 20%-85%RH and temperature of 25-55°C. This study demonstrates that HMSS@CDs-PCs sensors have practical application potential in indoor and outdoor chloroform vapor detection.

Nucleic acid‐templated chemical reactions for nucleic acid detection

AbstractNucleic 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.

Rapid‐Response and Portable Lead Ion Sensor Using Co/Pt/Si Schottky Heterojunction Without Reference Electrode

AbstractLead ions (Pb2+) are classified as highly toxic heavy metals that pose substantial threats to both human health and environmental integrity. Consequently, the sensitive detection of Pb2+, particularly at low concentrations, is imperative for the purposes of environmental surveillance and safeguarding public health. Here, we introduce a Co/Pt/Si Schottky heterostructure for a rapid, portable Pb2+ detection sensor. One electrode of the heterojunction serves as a Pb2+ probe, and sensor processing circuits are integrated. The Co/Pt thin films were deposited via magnetron sputtering on a Si(100) substrate, followed by heterojunction fabrication using semiconductor process technology. The sensor is functionalized with a glutathione‐modified gold electrode, leveraging the sulfur‐donor properties of cysteine in glutathione and the electron‐acceptor behavior of Pb2+. This interaction modulates the surface potential of the gold electrode, altering the current‐voltage rectification of the Co/Pt/Si heterojunction. A two‐terminal configuration enables current signal readout without reference electrodes. The sensor demonstrates a linear response to Pb2+ concentrations ranging from 1×10−8 to 1×10−3 mol/L, with high selectivity attributed to the affinity of glutathione for Pb2+. The key benefits are the simplicity of its fabrication process and its portability, which are enhanced by the integration of measurement circuitry. This makes the sensor a promising candidate for rapid, on‐site detection of heavy metal ions in applications related to health and environmental monitoring.

Pristine NiMOF Sandwiched between 1D and 3D Engineered Au Particles and Dendrites for Ultraswift Folic Acid Sensing in Cellular Microenvironment.

Catalytic metal-organic frameworks (MOFs)-based sensor matrices can act synergistically with Au metallic nanostructures to generate amplified signal readouts by causing the electro-oxidation of the target analyte. Folic acid (FA), an essential water-soluble vitamin and a precursor for enzymes, requires timely and precise monitoring in the serum of individuals with varying clinical diagnoses. An attempt has been made in this direction through our work, where the rapid detection of FA through its oxidation at metal centers from hybrid nanomaterials is deployed for signal generation. A nonenzymatic, nonimmunometric approach involving a sandwich model, comprising NiMOF layered between gold nanoparticles (AuNPs) and gold nanodendrites (AuNDs) incorporated within a sensor matrix, has been deployed for this purpose. The probe displayed great analytical performance with a linear dynamic range (LDR) from 1 × 10-11 M to 1 × 10-3 M and a limit of detection (LOD) of 0.43 × 10-11 M. The probe's average response time with respect to changes in FA concentration was recorded as less than 2.1 s, making it a rapid sensing platform for FA detection. The real-life applicability of the developed sensor was tested in serum, followed by analysis in a breast cancer cellular microenvironment, which yielded a current recovery between 95.11 and 98.17%. The in vitro analysis was further validated through live-cell imaging using the standard method of fluorescence. The shorter fabrication time of the developed sensor compared to existing ones makes it a facile and efficient sensing platform for FA detection in clinical settings. This study represents the first report on the conjunction of 1D, 2D, and 3D materials as a sensing matrix for molecular detection applications.

High-resolution TOF-DOI PET detectors through the implementation of dual-ended readout with SiPM arrays of different pixel sizes on the two ends.

Anorgan-specific Positron emission tomography (PET) scanner can achieve the same sensitivity with much fewer detectors as compared to a whole-body PET scanner, thereby substantially reducing the system cost. It can also achieve much better spatial resolution as compared to a whole-body PET scanner since the photon noncollinearity effect is reduced by using smaller detector ring diameter. Consequently, the development of organ-specific PET scanners with high spatial resolution, high sensitivity, and low cost has been a major focus of international research in PET instrument development for many years. The focus of this work is to develop high-resolution depth encoding PET detectors with high timing resolution and a reduced number of signal processing electronic channels. Consequently, PET scanners tailored for specific organs can be developed with high spatial and timing resolutions, enhanced sensitivity, and affordable cost. An 8×8 silicon photomultiplier (SiPM) array with a pixel size of 3×3 mm2 and a multiplexed signal readout circuit is coupled to one end of the lutetium yttrium orthosilicate (LYSO) array with a glass light guide between them to achieve a good crystal identification of small crystals by using only four position-encoding energy signals. A 4×4 SiPM array with a pixel size of 6×6 mm2 and an individual readout circuit is coupled to the other end of the crystal array without a light guide to achieve a good coincidence timing resolution (CTR). The depth of interaction (DOI) of the detector is measured by ratio of the energies measured by the two SiPM arrays and can be used to correct the depth dependency of the timing. The flood histograms, energy resolutions (ERs), DOI resolutions, and CTRs of two detectors utilizing LYSO arrays with different crystal sizes were measured with each of the two SiPM arrays alternately placed at the front of the detectors. A better flood histogram was obtained by placing the 8×8 SiPM array in front of the detector. The depth dependency of timing was larger when the 4×4 SiPM array was placed at the front of the detector. A better CTR was obtained by placing the 4×4 SiPM array at the back of the detector as compared to placing it at the front of the detector if the depth-dependent timing correction was not performed. If the depth-dependent timing correction was performed, a better CTR can be obtained by placing the 4×4 SiPM array at the front of the detector. The first detector using a 12×12 LYSO crystal array with a crystal size of 1.95×1.95×20 mm3 provided a flood histogram with all crystals clearly resolved, an ER of 11.7%, a DOI resolution of 2.9mm, and a CTR of 275ps with the depth-dependent timing correction. The second detector using a 23×23 LYSO crystal array with a crystal size of 0.95×0.95×20 mm3 provided a flood histogram with all but the edge crystals clearly resolved, an ER of 17.6%, a DOI resolution of 2.3mm, and a CTR of 293ps with the depth-dependent timing correction. PET detectors with small crystal cross-sectional sizes, good DOI and timing resolutions and a reduced number of electronics channels were developed. The detectors can be used to develop high performance organ-specific PET scanners.

Photonic Aptasensor Based on the Smart Cholesteric Liquid Crystal Network Structure for Cylindrospermopsin Detection.

Solid-state cholesteric liquid crystals (CLCsolid) with one-dimensional photonic structure offer a promising platform for constructing chemical and biological optical sensors, owing to their facile fabrication, signal readout, and sensitive and selective responsiveness to target analytes. In this study, we designed a CLCsolid photonic structure intertwined with an interpenetrating polymeric network (IPN) immobilized with a cylindrospermopsin aptamer (CY9) for the selective detection of the cylindrospermopsin toxin (CYT) in water. Upon exposure to CYT, it induced a blue shift in the color of the IPNCY9 biosensor chip. This shift occurred because the CY9 aptamer selectively bound to the CYT, reducing the polarity of the IPN hydrogel, leading to water release and shrinkage of the photonic structure. The IPNCY9 biosensor chips demonstrated the ability to detect CYT within a linear range of 4.2-120 nM, with a limit of detection of 2.55 nM. This innovative biosensor chip not only provides a new strategy for designing targeted toxin biosensors by immobilizing different receptors but also exhibits significant potential for use in portable kits for remote areas.