Dynamic profiles of lncRNAs reveal a functional natural antisense RNA that regulates the development of Schistosoma japonicum.

Schistosomes are flatworm parasites that undergo a complex life cycle involving two hosts. The regulation of the parasite's developmental processes relies on both coding RNAs and non-coding RNAs. However, the roles of non-coding RNAs, including long non-coding RNAs (lncRNAs) in schistosomes remain largely unexplored. Here we conduct advanced RNA sequencing on male and female S. japonicum during their pairing and reproductive development, resulting in the identification of nearly 8,000 lncRNAs. This extensive dataset enables us to construct a comprehensive co-expression network of lncRNAs and mRNAs, shedding light on their interactions during the crucial reproductive stages within the mammalian host. Importantly, we have also revealed a specific lncRNA, LNC3385, which appears to play a critical role in the survival and reproduction of the parasite. These findings not only enhance our understanding of the dynamic nature of lncRNAs during the reproductive phase of schistosomes but also highlight LNC3385 as a potential therapeutic target for combating schistosomiasis.

Crystal Structure of the Photosensory Module from a PAS-Less Cyanobacterial Phytochrome as Pr Shows a Mix of Dark-Adapted and Photoactivated Features.

Phytochromes (Phys) are a diverse collection of photoreceptors that regulate numerous physiological and developmental processes in microorganisms and plants through photointerconversion between red-light absorbing Pr and far-red light-absorbing Pfr states. Light is detected by an N-terminal photosensing module (PSM) sequentially comprised of Period/ARNT/Sim (PAS), cGMP-phosphodiesterase/adenylyl cyclase/FhlA (GAF), and Phy-specific (PHY) domains, with the bilin chromophore covalently-bound within the GAF domain. Phys sense light via the Pr/Pfr ratio measured by light-induced rotation of the bilin D-pyrrole ring that triggers conformational changes within the PSM, which for microbial Phys reaches into an output region. A key step is a ß-stranded to α-helical reconfiguration of a hairpin loop extending from the PHY domain to contact the GAF domain. Besides canonical Phys, cyanobacteria express several variants, including a PAS-less subfamily that harbors just the GAF and PHY domains for light detection. Prior 2D-NMR studies of a model PAS-less Phy from Synechococcus_sp._JA-2-3B'a(2-13) (SyB-Cph1) proposed a unique photoconversion mechanism involving an A-pyrrole ring rotation, while magic-angle-spinning NMR probing the chromophore proposed the prototypic D-ring flip. To help solve this conundrum, we determined the crystallographic structure of the GAF-PHY region from SyB-Cph1 as Pr. Surprisingly, this structure differs from canonical Phys by having a Pr ZZZsyn,syn,anti bilin configuration but shifted to the activated position in the binding pocket with consequent folding of the hairpin loop to α-helical, an architecture common for Pfr. Collectively, the PSM of SyB-Cph1 as Pr displayed a mix of dark-adapted and photoactivated features whose co-planar A-C pyrrole rings supports a D-ring flip mechanism.

PROCESS Trial: Effect of Duloxetine Premedication for Postherpetic Neuralgia Within 72 Hours of Herpes Zoster Reactivation-A Randomized Controlled Trial.

BACKGROUND: Postherpetic neuralgia (PHN) is the most common chronic complication of herpes zoster (HZ) and results in severe refractory neuropathic pain. This study aimed at evaluating the efficacy of premedication with duloxetine in the prevention of PHN. METHODS: The PROCESS trial is a multicenter, randomized, open-label, blinded-endpoint trial used a 1:1 duloxetine:control ratio. Adults 50 years or older with HZ who presented with vesicles within 72 hours were recruited. The primary outcome was the incidence of PHN at 12 weeks. PHN was defined as any pain intensity score other than 0 mm on the visual analog scale (VAS) at week 12 after the onset of the rash. The secondary outcomes were the number of participants with VAS >0 and VAS ≥3. The modified intention-to-treat (mITT) principle and per-protocol (PP) principle were used for the primary outcome analysis. RESULTS: A total of 375 participants were randomly assigned to the duloxetine group and 375 were assigned to the control group. There was no significant difference in the incidence of PHN in the duloxetine group compared with the control group in the mITT analysis (86 [22.9%] of 375 vs 108 [28.8%] of 375; P = .067). PP analysis produced similar results. However, there were significant differences between the 2 groups in the number of participants with VAS >0 and VAS ≥3 (P < .05 for all comparisons). CONCLUSIONS: Although absolute prevention of PHN does not occur, this trial found that premedication with duloxetine can reduce pain associated with HZ, and therefore can have clinically relevant benefits. Clinical Trials Registration. Clinicaltrials.gov, NCT04313335. Registered on 18 March 2020.

Projections from infralimbic medial prefrontal cortex glutamatergic outputs to amygdala mediates opioid induced hyperalgesia in male rats.

Repeated use of opioid analgesics may cause a paradoxically exacerbated pain known as opioid-induced hyperalgesia (OIH), which hinders effective clinical intervention for severe pain. Currently, little is known about the neural circuits underlying OIH modulation. Previous studies suggest that laterocapsular division of the central nucleus of amygdala (CeLC) is critically involved in the regulation of OIH. Our purpose is to clarify the role of the projections from infralimbic medial prefrontal cortex (IL) to CeLC in OIH. We first produced an OIH model by repeated fentanyl subcutaneous injection in male rats. Immunofluorescence staining revealed that c-Fos-positive neurons were significantly increased in the right CeLC in OIH rats than the saline controls. Then, we used calcium/calmodulin-dependent protein kinase IIα (CaMKIIα) labeling and the patch-clamp recordings with ex vivo optogenetics to detect the functional projections from glutamate pyramidal neurons in IL to the CeLC. The synaptic transmission from IL to CeLC, shown in the excitatory postsynaptic currents (eEPSCs), inhibitory postsynaptic currents (eIPSCs) and paired-pulse ratio (PPR), was observably enhanced after fentanyl administration. Moreover, optogenetic activation of this IL-CeLC pathway decreased c-Fos expression in CeLC and ameliorated mechanical and thermal pain in OIH. On the contrary, silencing this pathway by chemogenetics exacerbated OIH by activating the CeLC. Combined with the electrophysiology results, the enhanced synaptic transmission from IL to CeLC might be a cortical gain of IL to relieve OIH rather than a reason for OIH generation. Scaling up IL outputs to CeLC may be an effective neuromodulation strategy to treat OIH.

Charge Density-Regulated Microchannel-Based Electrochemiluminescence Sensor for Hydrogen Sulfide Detection with a Highly Efficient Accumulation Strategy.

The electrochemiluminescence (ECL) intensity can be regulated by ionic current passing through the microchannel, which broadened the regulation of the ECL sensors. But in the early reported sensors, the electrostatic repulsion and steric hindrance caused few targets to approach the interface of the microchannel driven by concentration difference, which reduced the detection efficiency and prolonged the detection period. In this study, different accumulation strategies, such as a positive electric field and different polarity electric fields, were designed to accumulate targets in the microchannel. The interaction of azide groups and hydrogen sulfide served as a research model. Hydrogen sulfide can react with the negatively charged azide groups in the microchannel surface to produce positively charged amino groups, decreasing the negative charge density of the microchannel and thus altering the ionic current and ECL intensity. The accumulation of hydrogen sulfide at the microchannel tip can increase the collision probability with azide groups to improve the detection efficiency, and the integration of accumulation and reaction can shorten the detection period to 28 min. The hydrogen sulfide concentration on the microchannel tip accumulated by applying different polarity electric fields was 22.3-fold higher than that accumulated by applying a positive electric field. The selected research model broadened the application range of a microchannel-based ECL sensor and confirmed the universality of the microchannel-based ECL sensor.

Photoelectrochemical Sensor for H2S Based on a Lead-Free Perovskite/Metal-Organic Framework Composite.

Halide perovskites have emerged as a highly promising class of photoelectric materials. However, the application of lead-based perovskites has been hindered by their toxicity and relatively weak stability. In this work, a composite material comprising a lead-free perovskite cesium copper iodide (CsCu2I3) nanocrystal and a metal-organic framework (MOF-801) has been synthesized through an in situ growth approach. The resulting composite material, denoted as CsCu2I3/MOF-801, demonstrates outstanding stability and exceptional optoelectronic characteristics. MOF-801 may serve a dual role by acting as a protective barrier between CsCu2I3 nanocrystals and the external environment, as well as promoting the efficient transfer of photogenerated charge carriers, thereby mitigating their recombination. Consequently, CsCu2I3/MOF-801 demonstrates its utility by providing both stability and a notably high initial photocurrent. Leveraging the inherent reactivity between H2S and the composite material, which results in the formation of Cu2S and structural alteration, an exceptionally sensitive photoelectrochemical sensor for H2S detection has been designed. This sensor exhibits a linear detection range spanning from 0.005 to 100 µM with a remarkable detection limit of 1.67 nM, rendering it highly suitable for precise quantification of H2S in rat brains. This eco-friendly sensor significantly broadens the application horizon of perovskite materials and lays a robust foundation for their future commercialization.

Cultivated alien plants with high invasion potential are more likely to be traded online in China.

Biological invasions have become a worldwide problem, and measures to efficiently prevent and control invasions are still in development. Like many other parts of the world, China is undergoing a dramatic increase in plant invasions. Most of the currently 933 established (i.e., naturalized) plant species, of which 214 are categorized as invasive, have been introduced into China for cultivation. It is likely that many of those species are still being traded, particularly online, by plant nurseries. However, studies assessing whether naturalized and invasive species are currently being traded more or less than nonnaturalized aliens are rare. We extracted online-trade information for 13,718 cultivated alien plant taxa on 1688.com, the largest website for domestic B2B in China. We analyzed how the presence in online-nursery catalogs, the number of online nurseries that offerred the species for sale, and the product type (i.e., seeds, live plants and vegetative organs) differed among nonnaturalized, naturalized noninvasive, and invasive species. Compared to nonnaturalized taxa, naturalized noninvasive and invasive taxa were 3.7-5.2 times more likely to be available for purchase. Naturalized noninvasive and invasive taxa were more frequently offered as seeds by online nurseries, whereas nonnaturalized taxa were more frequently offered as live plants. Based on these findings, we propose that, to reduce the further spread of invasive and potentially invasive plants, implementation of plant-trade regulations and a monitoring system of the online horticultural supply chain will be essential.

Direct Synthesis of α-Ketothioamide Derivatives through a One-Pot Reaction of Sulfur Ylides, Nitrosobenzenes, and Thioacetic Acid.

A one-pot approach has been developed for the synthesis of α-ketothioamide derivatives from sulfur ylides, nitrosobenzenes, and thioacetic acid. This protocol is carried out under mild reaction conditions in generally moderate to excellent yields without any precious catalysts, affording the derivatives with structural diversity. Additionally, a possible mechanism for this chemical transformation is proposed.

r20 (S)-protopanaxatriol improves atherosclerosis by inhibiting low-density lipoprotein receptor degradation in ApoE KO mice.

Atherosclerosis (AS) is a chronic progressive disease caused by various factors and causes various cerebrovascular and cardiovascular diseases (CVDs). Reducing the plasma levels of low-density lipoprotein-cholesterol (LDL-C) is the primary goal in preventing and treating AS. Proprotein Convertase Subtilisin/Kexin Type 9 (PCSK9) plays a crucial role in regulating LDL-C metabolism. Panax notoginseng has potent lipid-reducing effects and protects against CVDs, and its saponins induce vascular dilatation, inhibit thrombus formation, and are used in treating CVDs. However, the anti-AS effect of the secondary metabolite, 20(S) protopanaxatriol (20(S)-PPT), remains unclear. In this study, the anti-AS effect and molecular mechanism of 20(S)-PPT were investigated in vivo and in vitro by western blotting, real time-polymerase chain reaction (RT-PCR), Enzyme-linked Immunosorbent Assay (ELISA), immunofluorescence staining, and other assays. The in vitro experiments revealed that 20(S)-PPT reduced the levels of PCSK9 in the supernatant of HepG2 cells, upregulated low density lipoprotein receptor (LDLR) protein levels, promoted LDL uptake by HepG2 cells, and reduced PCSK9 mRNA transcription by upregulating the levels of FoxO3 protein and mRNA and decreasing the levels of HNF1α and SREBP2 protein and mRNA. The in vivo experiments revealed that 20(S)-PPT upregulated aortic αSMA expression, increased the stability of atherosclerotic plaques, and reduced aortic plaque formation induced by a high-cholesterol fed in ApoE-/- mice (HCF group). Additionally, 20(S)PPT reduced the aortic expression of CD68, reduced inflammation in the aortic root, and alleviated the hepatic lesions in the HCF group. The study revealed that 20(S)-PPT inhibited LDLR degradation via PCSK9 to alleviate AS.

Eu MOF-enhanced FeNCD nanozymes for fluorescence and highly sensitive colorimetric detection of tetracycline.

The constrained enzymatic activity and aggregation challenges encountered by small-sized nanozymes pose obstacles to their practical utility, necessitating a strategy to mitigate aggregation and boost enzymatic catalytic efficiency. In this work, a negatively charged Eu MOF was utilized as the encapsulation matrix, encapsulating the small-sized nanozymes FeNCDs into the Eu MOF to synthesize an FeNCDs@Eu MOF. The dispersibility of the encapsulated FeNCDs was increased, and owing to the negative charge of the FeNCDs@Eu MOF, electrostatic pre-concentration of the positively charged target molecule tetracycline (TC) was facilitated, thereby amplifying the enzymatic catalytic efficiency of the FeNCDs. The response of the FeNCDs to TC increased by nearly 6 times upon encapsulation. The TC detection limit (LOD) of the FeNCDs@Eu MOF-based sensor is as low as 11.63 nM. The incorporation of fluorescence detection expanded the linear range of the sensor, rendering it more suitable for practical sample detection.

The role of perioperative sedative anesthetics in preventing postoperative delirium: a systematic review and network-meta analysis including 6679 patients.

OBJECTIVE: Postoperative delirium is a common and debilitating complication that significantly affects patients and their families. The purpose of this study is to investigate whether there is an effective sedative that can prevent postoperative delirium while also examining the safety of using sedatives during the perioperative period. METHODS: The net-meta analysis was used to compare the incidence of postoperative delirium among four sedatives: sevoflurane, propofol, dexmedetomidine, and midazolam. Interventions were ranked according to their surface under the cumulative ranking curve (SUCRA). RESULTS: A total of 41 RCT studies involving 6679 patients were analyzed. Dexmedetomidine can effectively reduce the incidence of postoperative delirium than propofol (OR 0.47 95% CI 0.25-0.90), midazolam (OR 0.42 95% CI 0.17-1.00), normal saline (OR 0.42 95% CI 0.33-0.54) and sevoflurane (OR 0.39 95% CI 0.18-0.82). The saline group showed a significantly lower incidence of bradycardia compared to the group receiving dexmedetomidine (OR 0.55 95% CI 0.37-0.80). In cardiac surgery, midazolam (OR 3.34 95%CI 2.04-5.48) and normal saline (OR 2.27 95%CI 1.17-4.39) had a higher rate of postoperative delirium than dexmedetomidine, while in non-cardiac surgery, normal saline (OR 1.98 95%CI 1.44-2.71) was more susceptible to postoperative delirium than dexmedetomidine. CONCLUSION: Our analysis suggests that dexmedetomidine is an effective sedative in preventing postoperative delirium whether in cardiac surgery or non-cardiac surgery. The preventive effect of dexmedetomidine on postoperative delirium becomes more apparent with longer surgical and extubation times. However, it should be administered with caution as it was found to be associated with bradycardia.

Synthesis and antitumor activities of novel 3-(6-aminopyridin-3-yl)benzamide derivatives: Inducing cell cycle arrest and apoptosis via AURKB transcription inhibition.

Here, a series of 3-(6-aminopyridin-3-yl) benzamide derivatives were designed and synthesized. Cell viability assay indicated that most compounds exhibited potent antiproliferative activity against all the tested cancer cells. Among them, compound 7l displayed the best antiproliferative activity particularly in A549 cells, with an IC50 value of 0.04 ± 0.01 µM. RNA-seq analysis was employed to explore the potential pathways related to the antiproliferative activity of compound 7l. The data revealed that 7l exerted antiproliferative activity mainly by regulating cell cycle, DNA replication and p53 signaling pathway. Indeed, compound 7l induced G2/M phase arrest by AURKB transcription inhibition and resulted in cell apoptosis via p53 signaling pathway. Most importantly, compound 7l demonstrated potent antitumor activity in A549 xenograft tumor model. Collectively, 7l might be a promising lead compound for the development of new therapeutic agents for AURKB overexpressed or mutated cancers.

Ethnic disparities and temporal trends in health resource allocation: a retrospective decadal analysis in Sichuan, a multi-ethnic Province of Southwest China (2009-2019).

BACKGROUND: Research on health resource allocation trends in ethnic minority and impoverished areas in China is limited since the 2009 Medical Reform. This study aimed to investigate the variations and inequalities in health resource distribution among ethnic minority, poverty-stricken, and non-minority regions in Sichuan Province, a multi-ethnic province in Southwest China, from 2009 to 2019. METHODS: The numbers of beds, doctors and nurses were retrospectively sourced from the Sichuan Health Statistics Yearbook between 2009 and 2019. All the 181 counties in Sichuan Province were categorized into five groups: Yi, Zang, other ethnic minority, poverty-stricken, and non-minority county. The Theil index, adjusted for population size, was used to evaluate health resource allocation inequalities. RESULTS: From 2009 to 2019, the number of beds (Bedp1000), doctors (Docp1000), and nurses (Nurp1000) per 1000 individuals in ethnic minority and poverty-stricken counties consistently remained lower than non-minority counties. The growth rates of Bedp1000 in Yi (140%) and other ethnic minority counties (127%) were higher than in non-minority counties (121%), while the growth rates of Docp1000 in Yi (20%) and Zang (11%) counties were lower than non-minority counties (61%). Docp1000 in 33% and 50% of Yi and Zang ethnic counties decreased, respectively. Nurp1000 in Yi (240%) and other ethnic minority (316%) counties increased faster than non-minority counties (198%). The Theil index for beds and nurses declined, while the index for doctors increased. Key factors driving increases in bed allocation include preferential policies and economic development levels, while health practitioner income, economic development levels and geographical environment significantly influence doctor and nurse allocation. CONCLUSIONS: Preferential policies have been successful in increasing the number of beds in health facilities, but not healthcare workers, in ethnic minority regions. The ethnic disparities in doctor allocation increased in Sichuan Province. To increase the number of doctors and nurses in ethnic minority and poverty-stricken regions, particularly in Yi counties, more preferential policies and resources should be introduced.

Contributions to Constructing Forced-Choice Questionnaires Using the Thurstonian IRT Model.

Forced-choice questionnaires involve presenting items in blocks and asking respondents to provide a full or partial ranking of the items within each block. To prevent involuntary or voluntary response distortions, blocks are usually formed of items that possess similar levels of desirability. Assembling forced-choice blocks is not a trivial process, because in addition to desirability, both the direction and magnitude of relationships between items and the traits being measured (i.e., factor loadings) need to be carefully considered. Based on simulations and empirical studies using item pairs, we provide recommendations on how to construct item pairs matched by desirability. When all pairs contain items keyed in the same direction, score reliability is improved by maximizing within-block loading differences. Higher reliability is obtained when even a small number of pairs consist of unequally keyed items.

Physical conditioning methods for sludge deep dewatering: A critical review.

Sludge is an inevitable waste product of sewage treatment with a high water content and large volume, it poses a significant threat of secondary pollution to both water and the atmosphere without proper disposal. In this regard, dewatering has emerged as an attractive method in sludge treatment, as it can reduce the sludge volume, enhance its transportability and calorific value, and even decrease the production of landfill leachate. In recent years, physical conditioning methods including non-chemical conditioners or energy input alone, have been extensively researched for their potential to enhance sludge dewatering efficiency, such as thermal treatment, freeze-thaw, microwave, ultrasonic, skeleton builders addition, and electro-dewatering, as well as combined methods. The main objective of this paper is to comprehensively evaluate the dewatering capacity of various physical conditioning methods, and identify key factors affecting sludge dewatering efficiency. In addition, future research anticipated directions and outlooks are proposed. This work is expected to provide valuable insights for developing efficient, eco-friendly, and low-energy consumption techniques for deep sludge dewatering.

Structural and Reactivity Effects of Secondary Metal Doping into Iron-Nitrogen-Carbon Catalysts for Oxygen Electroreduction.

While improved activity was recently reported for bimetallic iron-metal-nitrogen-carbon (FeMNC) catalysts for the oxygen reduction reaction (ORR) in acid medium, the nature of active sites and interactions between the two metals are poorly understood. Here, FeSnNC and FeCoNC catalysts were structurally and catalytically compared to their parent FeNC and SnNC catalysts. While CO cryo-chemisorption revealed a twice lower site density of M-Nx sites for FeSnNC and FeCoNC relative to FeNC and SnNC, the mass activity of both bimetallic catalysts is 50-100% higher than that of FeNC due to a larger turnover frequency in the bimetallic catalysts. Electron microscopy and X-ray absorption spectroscopy identified the coexistence of Fe-Nx and Sn-Nx or Co-Nx sites, while no evidence was found for binuclear Fe-M-Nx sites. 57Fe Mössbauer spectroscopy revealed that the bimetallic catalysts feature a higher D1/D2 ratio of the spectral signatures assigned to two distinct Fe-Nx sites, relative to the FeNC parent catalyst. Thus, the addition of the secondary metal favored the formation of D1 sites, associated with the higher turnover frequency.

Chemical Kinetic Method for Active-Site Quantification in Fe-N-C Catalysts and Correlation with Molecular Probe and Spectroscopic Site-Counting Methods.

Mononuclear Fe ions ligated by nitrogen (FeNx) dispersed on nitrogen-doped carbon (Fe-N-C) serve as active centers for electrocatalytic O2 reduction and thermocatalytic aerobic oxidations. Despite their promise as replacements for precious metals in a variety of practical applications, such as fuel cells, the discovery of new Fe-N-C catalysts has relied primarily on empirical approaches. In this context, the development of quantitative structure-reactivity relationships and benchmarking of catalysts prepared by different synthetic routes and by different laboratories would be facilitated by the broader adoption of methods to quantify atomically dispersed FeNx active centers. In this study, we develop a kinetic probe reaction method that uses the aerobic oxidation of a model hydroquinone substrate to quantify the density of FeNx centers in Fe-N-C catalysts. The kinetic method is compared with low-temperature Mössbauer spectroscopy, CO pulse chemisorption, and electrochemical reductive stripping of NO derived from NO2- on a suite of Fe-N-C catalysts prepared by diverse routes and featuring either the exclusive presence of Fe as FeNx sites or the coexistence of aggregated Fe species in addition to FeNx. The FeNx site densities derived from the kinetic method correlate well with those obtained from CO pulse chemisorption and Mössbauer spectroscopy. The broad survey of Fe-N-C materials also reveals the presence of outliers and challenges associated with each site quantification approach. The kinetic method developed here does not require pretreatments that may alter active-site distributions or specialized equipment beyond reaction vessels and standard analytical instrumentation.

Multicolor Biosensor for Trypsin Detection Based on the Regulation of the Peroxidase Activity of Bovine Serum Albumin-Coated Gold Nanoclusters and Etching of Gold Nanobipyramids.

The detection of trypsin is significantly important for both clinical diagnosis and disease treatment. In this study, an innovative multicolor sensor for trypsin detection has been established based on the regulation of the peroxidase activity of bovine serum albumin-coated gold nanoclusters (BSA-Au NCs) and efficient etching of gold nanobipyramids (Au NBPs). BSA-Au NCs have slight peroxidase enzyme activity and can catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) to generate TMB+, while trypsin can hydrolyze BSA ligands on the surface of BSA-Au NCs, thus exposing more catalytic active sites of BSA-Au NCs and resulting in the enhancement of the peroxidase activity of BSA-Au NCs, hence more TMB+ is generated. Under acidic conditions, TMB+ can etch Au NBPs efficiently, consequently affecting the aspect ratio of Au NBPs accompanied by the ultraviolet-visible (UV-vis) spectra blue shifting of the system. Furthermore, this also results in color variations that can be distinguished and recognized by naked eyes without any expensive and sophisticated instruments. This multicolor sensor has an available linear relationship with the logarithm of the trypsin concentration in the range of 0.1-100 µg/mL, and the detection limit is 0.045 µg/mL. The designed sensor has been used to detect the concentration of trypsin in human serum samples from healthy individuals and pancreatitis patients with satisfactory results.

Low-Background Signal-On Homogeneous Electrochemiluminescence Biosensor for Hepatitis B Virus Detection Based on the Regulation of the Length of DNA Modified on the Nanoparticles by CRISPR/Cas12a and Hybridization Chain Reaction.

In this work, combined with the high amplification efficiency of hybridization chain reaction (HCR), high specificity of the CRISPR/Cas12a system, and convenience of the homogeneous electrochemiluminescence (ECL) assay based on the regulation of negative charge on the reporting probes, a sensitive ECL biosensor for hepatitis B virus DNA (chosen as a model target) had been developed. The initiator chain trigger DNA that can induce HCR amplification is modified on the surface of ruthenium bipyridine-doped silica nanoparticles (Ru@SiO2 NPs) first, and large amounts of negative charges modified on the particles were achieved through the HCR amplification reaction. The efficiency of the nanoparticles reaching the negatively charged working electrode can be regulated and realize the change of the ECL signal. In addition, long DNA on the surface of the luminescent body may prevent the coreactant from entering the pore to react with ruthenium bipyridine. These factors combine to produce a low-background system. The presence of the target can activate the CRISPR/Cas12a system and make trigger DNA disappear from the nanoparticle surface, and strong ECL can be detected. The sensor does not require a complex electrode modification; therefore, it has better reproducibility. Additionally, due to dual signal amplification, the sensor has a high sensitivity. In the range of 10 fM to 10 nM, the ECL intensity exhibits a strong linear relationship with the logarithm of the target concentration, and the detection limit is 7.41 fM. This sensor has shown high accuracy in detecting clinical samples, which holds significant potential for application in clinical testing.

Dual Self-Amplification Homogeneous Electrochemiluminescence Biosensor for Terminal Deoxynucleotidyl Transferase Activity Based on Controlling the Surface Morphology and Charge of Reporter Nanoparticles.

Terminal deoxynucleotidyl transferase (TdT) is upregulated in several types of leukemia and is considered a disease biomarker and a potential therapeutic target for leukemia. In this research, a homogeneous electrochemiluminescence (ECL) method based on the control of surface charge and morphology of tris (2,2'-bipyridine) ruthenium(II) chloride hexahydrate-doped silica nanoparticles (Ru@SiO2 NPs) has been designed for TdT activity detection. A small amount of short single-stranded DNA (ssDNA) was modified onto the surface of Ru@SiO2 NPs, and the nanoparticles with a slight positive charge experienced electrostatic attraction with the indium tin oxide (ITO) electrode with a negative charge, so relatively high ECL signals had been detected. Under the action of TdT, the ssDNA was significantly elongated, carrying numerous negative charges on its phosphate backbone, so the overall negative charge of the reporter nanoparticles was enhanced, resulting in a strong electrostatic repulsion with the ITO electrode. Simultaneously, the long ssDNA wrapped around the nanoparticles hindered the approach of the coreactant. Due to the dual effects, the ECL response of the system decreased. The constructed biosensor exhibited excellent sensitivity toward TdT over a range spanning from 1 to 100 U/L. The limit of detection is as low as 1.78 U/L. The developed approach was effectively applied to detect TdT activity in leukemic patients' leukocyte extracts.