Adsorption of typical NDMA precursors by superfine powdered activated carbon: Critical role of particle size reduction.

Control of N-nitrosodimethylamine (NDMA) in drinking water could be achieved by removing its precursors as one practical way. Herein, superfine powdered activated carbons with a diameter of about 1 µm (SPACs) were successfully prepared by grinding powdered activated carbon (PAC, D50=24.3 µm) and applied to remove model NDMA precursors, i.e. ranitidine (RAN) and nizatidine (NIZ). Results from grain diameter experiments demonstrated that the absorption velocity increased dramatically with decreasing particle size, and the maximum increase in k2 was 26.8-folds for RAN and 33.4-folds for NIZ. Moreover, kinetic experiments explained that rapid absorption could be attributed to the acceleration of intraparticle diffusion due to the shortening of the diffusion path. Furthermore, performance comparison experiments suggested that the removal of RAN and NIZ (C0=0.5 mg/L) could reach 61.3% and 60%, respectively, within 5 min, when the dosage of SAPC-1.1 (D50=1.1 µm) was merely 5 mg/L, while PAC-24.3 could only eliminate 17.5% and 18.6%. The adsorption isotherm was well defined by Langmuir isotherm model, indicating that the adsorption of RAN/NIZ was a monolayer coverage process. The adsorption of RAN or NIZ by SAPC-1.1 and PAC-24.3 was strongly pH dependent, and high adsorption capacity could be observed under the condition of pH > pka+1. The coexistence of humic acid (HA) had no significant effect on the adsorption performance because RAN/NIZ may be coupled with HA and removed simultaneously. The coexistence of anions had little effect on the adsorption also. This study is expected to provide an alternative strategy for drinking water safety triggered by NDMA.

Automated In Vivo Phenotypic Screening Platform for Identifying Factors that Affect Cell Regeneration Kinetics.

Various strategies for replacing retinal neurons lost in degenerative diseases are under investigation, including stimulating the endogenous regenerative capacity of Müller Glia (MG) as injury-inducible retinal stem cells. Inherently regenerative species, such as zebrafish, have provided key insights into mechanisms regulating MG dedifferentiation to a stem-like state and the proliferation of MG and MG-derived progenitor cells (MGPCs). Interestingly, promoting MG/MGPC proliferation is not sufficient for regeneration, yet mechanistic studies are often focused on this measure. To fully account for the regenerative process, and facilitate screens for factors regulating cell regeneration, an assay for quantifying cell replacement is required. Accordingly, we adapted an automated reporter-assisted phenotypic screening platform to quantify the pace of cellular regeneration kinetics following selective cell ablation in larval zebrafish. Here, we detail a method for using this approach to identify chemicals and genes that control the rate of retinal cell regeneration following selective retinal cell ablation.

Plasmon-mediated photocatalytic conversion in Au or Ag nanorod aggregates by surface-enhanced Raman spectroscopy.

Plasmonic nanoparticles (NPs) hold considerable potential as photocatalysts owing to their robust light-matter interactions across diverse electromagnetic wavelengths, which significantly influence the photophysical characteristics of the adjacent molecular entities. Despite the widespread use of noble-metal NPs in surface-enhanced Raman scattering (SERS) applications, little is known about the kinetics of nanoparticle aggregation and how it affects their configurations. This study investigates the plasmon-driven photochemical conversion of 4-nitrobenzenethiol (NBT) to 4,4'-dimercaptoazobenzene (DMAB) on Au and Ag nanorods (NRs) through SERS. Significantly, photoconversion phenomena were observed on Ag NRs but not on Au NRs upon laser excitation at 633 nm. Finite-difference time-domain simulations revealed the presence of stronger electromagnetic fields on Ag NRs than on Au NRs. The aspect ratios and gaps between individual NPs in dimer configurations were determined to elucidate their effects on electromagnetic fields. The Ag NR dimer with an end-to-end configuration, an aspect ratio of 3.3, and a 1-nm gap exhibited the highest enhancement factor of 1.05 × 1012. Our results demonstrate that the primary contribution from diverse configurations in NR aggregates is the end-to-end configuration. The proposed NP design with adjustable parameters is expected to advance research in plasmonics, sensing, and wireless communications. These findings also contribute to the understanding of plasmon-driven photochemical processes in metallic nanostructures.

Fingertip light touch contact increases anteroposterior limits of stability in healthy young and older adults.

BACKGROUND: The limit of stability (LoS), an index of stance balance ability, is reduced in older adults. Although contacting an earth-fixed external surface through fingertips' light touch improves older adults' stance balance control, its effects on the LoS in this population are unclear. RESEARCH QUESTION: Does light touch increase the LoS and reduce postural sway in the LoS? METHODS: This study included 20 young adults (11 women and 9 men, mean age = 20.6 years) and 15 community-dwelling older adults (8 women and 7 men, mean age = 74.5 years). The position and path length of the center of pressure (CoP) during quiet standing (QS) and the anterior and posterior LoS (A-LoS and P-LoS, respectively) were measured using a force platform under two touch conditions (no-touch condition and light-touch condition). In light-touch condition, participants placed the tip of their dominant index finger on a load cell, which had an applied force of <1 N. RESULTS: In both touch conditions, the older group had a more limited CoP position in the anteroposterior LoS and a longer CoP path length in the QS and LoS than the younger group. In both participant groups, the light-touch condition showed a wider CoP position in the anteroposterior LoS and a shorter CoP path length in the QS and LoS than the no-touch condition. SIGNIFICANCE: Light touch increases the anteroposterior LoS and decreases postural sway in the LoS. Therefore, contacting an external object by fingertips' light touch may be an effective training protocol to increase the LoS in older adults.

Functional biochar accelerates peroxymonosulfate activation for organic contaminant degradation via the specific B-C-N configuration.

Functional biochar designed with heteroatom doping facilitates the activation of peroxymonosulfate (PMS), triggering both radical and non-radical systems and thus augmenting pollutant degradation efficiency. A sequence of functional biochar, derived from hyperaccumulator (Sedum alfredii) residues, was synthesized via sequential doping with boron and nitrogen. The SABC-B@N-2 exhibited outstanding catalytic effectiveness in activating PMS to degrade the model pollutant, acid orange 7 ( =0.0655 min-1), which was 6.75 times more active than the pristine biochar and achieved notable mineralization efficiency (71.98%) at reduced PMS concentration (0.1 mM). Relative contribution evaluations, using steady-state concentrations combined with electrochemical and in situ Raman analyses, reveal that co-doping with boron and nitrogen alters the reaction pathway, transitioning from PMS activation through multiple reactive oxygen species (ROSs) to a predominantly non-radical process facilitated by electron transfer. Moreover, the previously misunderstood concept that singlet oxygen (1O2) plays a central role in the degradation of AO7 has been clarified. Correlation analysis and density functional theory calculations indicate that the distinct BCN configuration, featuring the BC2O group and pyridinic-N, is fundamental to the active site. This research substantially advances the sustainability of phytoremediation by offering a viable methodology to synthesize highly catalytic functional biochar utilizing hyperaccumulator residues.

Modulating Interfacial Zn2+ Desolvation and Transport Kinetics through Coordination Interaction toward Stable Anodes in Aqueous Zn-Ion Batteries.

Aqueous Zn-ion batteries (AZIBs) are promising candidates for grid-scale energy-storage applications, but uneven Zn2+ flux distribution and undesirable water-related interfacial side reactions seriously hinder their practical application. Herein, a strategy of regulating the coordination interaction between Zn2+ and artificial interphase layers (AILs) to modulate the interfacial Zn2+ desolvation/transport behaviors and relieve side reactions for building stable Zn anodes is proposed. By selectively choosing appropriate polymers with different functional groups, it is shown that compared with the strong interaction offered by aryl groups in polystyrene-based AILs, cyano groups in polyacrylonitrile (PAN)-based AILs provide a moderate coordination interaction with Zn2+, which not only accelerates interfacial Zn2+desolvation kinetics but also enables efficient Zn2+ transport within AILs. Moreover, the Zn2+ transport kinetics of PAN-based AILs can be further enhanced with the incorporation of an ionic conductor, zinc phosphate (ZP). Because of these advantages, the Zn anodes decorated with the hybrid AILs composed of PAN and ZP can steadily operate for >2000 h at 0.2 mA cm-2 and >350 h at a high current density of 10 mA cm-2. This work provides a valuable guideline for selective design of AILs at the molecular level for durable AZIBs.

Collective effect of Vigna sp. (mung) tubulin GTP hydrolysis rate divergence on microtubule filament assembly.

Microtubules (MTs) are dynamic cytoskeletal filaments with highly conserved sequences across evolution, polymerizing by the GTP-dependent assembly of tubulin subunits. Despite the sequence conservation, MT polymerization kinetics diverge quantitatively between vertebrate brain, the model plant Arabidopsis and the protozoan Plasmodium. Previously, tubulin purified from seedlings of the plant Vigna sp. (mung) by temperature cycling was found to have a very low critical concentration. However, the lengths of MTs were sub-micron, much shorter than brain tubulin filaments. This was explained in simulations to be the result of the collective effect of high nucleation and GTP hydrolysis rates. Here, we test the effect of GTPase rates of affinity-purified Vigna sp. tubulin on microtubule polymerization and elongation. Affinity-purified mung tubulin is active and has a critical concentration of .37 µM. The GTP-dependent polymerization kinetics are transient, consistent with previous results. Polymerization is stabilized in the presence of either GTP analog GMPPNP (non-hydrolyzable) or GMPCPP (slow-hydrolyzable). Using interference reflection microscopy (IRM) we find polymerization with the non-hydrolysable analog significantly increases filament numbers, while lengths are unaffected for both GTP analogs. However, prolonged incubation with slow-hydrolyzable GMPCPP results in long filaments, pointing to GTP hydrolysis as a key factor determining MT length. We find the average GTPase turnover number of mung tubulin is 22.8 min-1, compared to 2.04 min-1 for goat brain tubulin. Thus modulating GTPase rates affects both nucleation and elongation. This quantitative divergence in kinetics despite high sequence conservation in the GTPase domains of α- and ß-tubulin could help better understand the roles of selective pressure and function in the diverse organisms.

Polycyclic aromatic hydrocarbon derivatives onto polar microplastics of polyurethane: equilibrium, thermodynamics, and kinetics of monolayer-multilayer adsorption.

The study of the adsorption of polycyclic aromatic hydrocarbons on microplastics (MPs) has attracted much attention as to how microplastics can act as carriers of these pollutants. Polyurethane (PU) is one of the MPs found in aquatic environments, containing different functional groups it can interact with polar and nonpolar molecules. PAH derivatives (dPAHs) present different properties and thus can be adsorbed by different interactions; thus, this study investigated the adsorption of fluorene (FLN), dibenzothiophene (DBT), dibenzofuran (DBF), and carbazole (CBZ) onto PU MP. The Langmuir, Freundlich, and BET isotherm models were examined, and the BET model best fitted. The adsorption was a nonspontaneous process, exothermic for mono- and multilayer formation for FLN, DBT, and CBZ, and endothermic for DBF monolayer formation. The adsorption monolayer was formed by van der Waals forces, H─bonding, and π─π interactions, while the formation of the multilayer can be explained by π─π and hydrophobic interactions. The pseudo-second-order model proved to be more consistent for the adsorption of dPAHs. The adsorption in artificial seawater shows no significant differences for the monolayer but favored the adsorption multilayer due to the salting-out effect. Due to the existence of several adsorption mechanisms, PU MP interacts with dPAHs in greater quantities when compared to a MP with a simpler structure.

Probing the nucleobase selectivity of RNA polymerases with dual-coding substrates.

Formycin A (FOR) and Pyrazofurin A (PYR) are nucleoside analogues with antiviral and antitumor properties. They are known to interfere with nucleic acid metabolism, but their direct effect on transcription is less understood. We explored how RNA polymerases (RNAPs) from bacteria, mitochondria, and viruses utilize FOR, PYR, and oxidized purine nucleotides. All tested polymerases incorporated FOR in place of adenine and PYR in place of uridine. FOR also exhibited surprising dual-coding behavior, functioning as a cytosine substitute, particularly for viral RNAP. In contrast, 8-oxoadenine and 8-oxoguanine were incorporated in place of uridine in addition to their canonical Watson-Crick codings. Our data suggest that the interconversion of canonical anti- and alternative syn-conformers underlies dual-coding abilities of FOR and oxidized purines. Structurally distinct RNAPs displayed varying abilities to utilize syn-conformers during transcription. By examining base pairings that led to substrate incorporation and the entire spectrum of geometrically compatible pairings, we have gained new insights into the nucleobase selection processes employed by structurally diverse RNAPs. These insights may pave the way for advancements in antiviral therapies.

Calcium kinetic rates in Caucasian males and females from birth to adulthood.

Calcium plays an important role in bone physiology and its kinetics change over lifetime. The analysis of calcium deposition and release through stable isotope techniques has guided recommendations on nutritional uptake for overall health. In addition, calcium kinetics have great relevance for toxicokinetic studies of bone-seeking elements (e.g, aluminium and lead) since these elements use common uptake and release pathways. While the impact of many factors on calcium kinetics have been investigated individually, a consolidated age- and sex-dependent kinetic description amenable for toxicokinetic modeling, however, is still lacking. Motivated by this need, we systematically reviewed the existing literature on calcium kinetics and assembled a large and consistent dataset. Then, building on the work of O'Flaherty in the 1990s, we formulated age- and sex-dependent functions describing calcium deposition, release, net retention, and mass. This description represents the current knowledge on calcium kinetics in a reference individual of Caucasians as most data was from this population.

Mastering Proton Activities in Aqueous Batteries.

Advanced aqueous batteries are promising solutions for grid energy storage. Compared with their organic counterparts, water-based electrolytes enable fast transport kinetics, high safety, low cost, and enhanced environmental sustainability. However, the presence of protons in the electrolyte, generated by the spontaneous ionization of water, may compete with the main charge-storage mechanism, trigger unwanted side reactions, and accelerate the deterioration of the cell performance. Therefore, it is of pivotal importance to understand and master the proton activities in aqueous batteries. This Perspective comments on the following scientific questions: Why are proton activities relevant? What are proton activities? What do we know about proton activities in aqueous batteries? How do we better understand, control, and utilize proton activities?

Does high-intensity running to fatigue influence lower limb injury risk?

OBJECTIVES: The aim of this study was to quantify changes in peak bending moments at the distal tibia, peak patellofemoral joint contact forces and peak Achilles tendon forces during a high-intensity run to fatigue at middle-distance speed. DESIGN: Observational study. METHODS: 16 high-level runners (7 female) ran on a treadmill at the final speed achieved during a preceding maximum oxygen uptake test until failure (~3 min). Three-dimensional kinetics and kinematics were used to derive and compare tibial bending moments, patellofemoral joint contact forces and Achilles tendon forces at the start, 33 %, 67 % and the end of the run. RESULTS: Average running speed was 5.7 (0.4) m·s-1. There was a decrease in peak tibial bending moments (-6.8 %, p = 0.004) from the start to the end of the run, driven by a decrease in peak bending moments due to muscular forces (-6.5 %, p = 0.001), whilst there was no difference in peak bending moments due to joint reaction forces. There was an increase in peak patellofemoral joint forces (+8.9 %, p = 0.026) from the start to the end of the run, but a decrease in peak Achilles tendon forces (-9.1 %, p < 0.001). CONCLUSIONS: Running at a fixed, high-intensity speed to failure led to reduced tibial bending moments and Achilles tendon forces, and increased patellofemoral joint forces. Thus, the altered neuromechanics of high-intensity running to fatigue may increase patellofemoral joint injury risk, but may not be a mechanism for tibial or Achilles tendon overuse injury development.

Variability in the acid adaptation of ten different O157:H7 and non-O157 Escherichia coli strains in orange juice and the impact on UV radiation resistance.

This study aimed to assess the impact of adaptation of ten strains of O157:H7 and non-O157 Escherichia coli to low pH (acid shock or slow acidification) and the effects of this exposure or not on the resistance of E. coli strains to UV radiation in orange juice (pH 3.5). The acid-shocked cells were obtained through culture in tryptic soy broth (TSB) with a final pH of 4.8, which was adjusted by hydrochloric, lactic, or citric acid and subsequently inoculated in orange juice at 4 °C for 30 days. No significant differences (p > 0.05) in survival in orange juice were observed between the serotypes O157:H7 and non-O157:H7 for acid-shocked experiments. After slow acidification, where the cells were cultured in TSB supplemented with glucose 1% (TSB + G), a significant increase (p < 0.05) in survival was observed for all strains evaluated. The D-values (radiation dose (J/cm2) necessary to decrease the microbial population by 90%) were determined as the inverse of the slopes of the regressions (k) obtained by plotting log (N/N0). The results show that among the strains tested, E. coli O157:H7 (303/00) and O26:H11 were the most resistant and sensitive strains, respectively. According to our results, the method of acid adaptation contributes to increasing the UV resistance for most of the strains tested.

Solvent Dependence of Ionic Liquid-Based Pt Nanoparticle Synthesis: Machine Learning-Aided In-Line Monitoring in a Flow Reactor.

Colloidal platinum nanoparticles (Pt NPs) possess a myriad of technologically relevant applications. A potentially sustainable route to synthesize Pt NPs is via polyol reduction in ionic liquid (IL) solvents; however, the development of this synthetic method is limited by the fact that reaction kinetics have not been investigated. In-line analysis in a flow reactor is an appealing approach to obtain such kinetic data; unfortunately, the optical featurelessness of Pt NPs in the visible spectrum complicates the direct analysis of flow chemistry products via ultraviolet-visible (UV-vis) spectrophotometry. Here, we report a machine learning (ML)-based approach to analyze in-line UV-vis spectrophotometric data to determine Pt NP product concentrations. Using a benchtop flow reactor with ML-interpreted in-line analysis, we were able to investigate NP yield as a function of residence time for two IL solvents: 1-butyl-1-methylpyrrolidinium triflate (BMPYRR-OTf) and 1-butyl-2-methylpyridinium triflate (BMPY-OTf). While these solvents are structurally similar, the polyol reduction shows radically different yields of Pt NPs depending on which solvent is used. The approach presented here will help develop an understanding of how the subtle differences in the molecular structures of these solvents lead to distinct reaction behavior. The accuracy of the ML prediction was validated by particle size analysis and the error was found to be as low as 4%. This approach is generalizable and has the potential to provide information on various reaction outcomes stemming from solvent effects, for example, differential yields, orders of reaction, rate coefficients, NP sizes, etc.

Kinetic Properties of Glutamate Carboxypeptidase II Partially Purified from Leukodystrophy Patient's Serum.

Glutamate carboxypeptidase II (GCPII), a metallopeptidase, is a recently identified pharmacologically targeted protein that is predominantly expressed in the human central nervous system, where it degrades the most abundant neuropeptide in the brain, N-acetyl aspartate glutamate, releasing free glutamate. Dysregulated glutamate release is associated with numerous neurological disorders and brain inflammation. The present study was designed to evaluate the activity of GCPII in 60 serum samples from patients with leukodystrophy and 30 samples from a control group with an age of less than 10 years. Subsequently, the enzyme was purified from the serum of leukodystrophy patients for experimental studies using ion exchange and gel filtration techniques to enhance the enzyme purity and reduce impurities. Finally, the kinetic properties of the purified enzyme were measured. The results of the present study demonstrated a reduction in the efficacy of the enzyme in comparison to the control group at a significance level of P ≤ 0.00003. Additionally, the kinetic study of the purified enzyme revealed a Michaelis-Menten constant value of 0.012 µM and a maximum velocity of 1.1318 µmol min-1. As demonstrated by the Lineweaver-Burk plot, using folate as the substrate, the Km value indicates the high affinity of the enzyme for folate, which is a crucial consideration in the development of therapies for neurological diseases. Additionally, the enzyme exhibited optimal activity at 37 °C and pH 7.4, with an incubation time of 5 min. The significance of GCPII in patients with leukodystrophy is 2-fold: first, it may serve as an early diagnostic marker for leukodystrophy, and second, it could represent a potential therapeutic target for neurological disorders.

Structure-based discovery of a 4,5-Dihydropyrazole-cored PET ligand for imaging of receptor-interacting serine/threonine-protein kinase 1 (RIPK1) in the brain.

Receptor-interacting serine/threonine-protein kinase 1 (RIPK1) regulates programmed cell death and inflammation, contributing to a wide range of human pathologies, including inflammatory disorders, neurodegenerative conditions, and cancer. Despite this, no RIPK1 positron emission tomography (PET) ligand with significant in vivo specificity has been reported to date. In this work, we designed and synthesized a new family of dihydropyrazole-cored ligands suitable for 18F-labeling at the late stage. Among these, WL8 showed a strong binding affinity to RIPK1 (EC50 = 19.9 nM, Kd = 25 nM) and was successfully labeled with 18F in the 6-position of pyridine ring, yielding a high radiochemistry yield of 27.9 % (decay-corrected) and a high molar activity of 18.8-31.2 GBq/µmol. In in vitro autoradiography, [18F]WL8 showed some specific binding in the brain sections of rats and lipopolysaccharide (LPS) model mice. Preliminary PET studies in rat brains revealed that [18F]WL8 could efficiently penetrate the blood-brain barrier and was rapidly washed out. As anticipated, [18F]WL8 exhibited a high initial uptake (brain2min = 4.80 % ID/g) in mouse brains, followed by a rapid washout (brain60min = 0.14 % ID/g), although no clear specific binding to RIPK1 was observed. Moderate in vivo stability was noted for [18F]WL8 in mouse brains with 35.2 % of the parent fraction remaining after 30 min post-administration. Altogether, our work broadens the landscape and offers a new chemotype for RIPK1 PET ligand development.

The Rapid-reaction Kinetics of an Electron-Bifurcating Flavoprotein, the crotonyl-CoA-dependent NADH:ferredoxin oxidoreductase EtfAB:bcd.

We have investigated the kinetic behavior of the electron-bifurcating crotonyl-CoA-dependent NADH: ferredoxin oxidoreductase EtfAB:bcd from Megasphaera elsdenii. The overall behavior of the complex in both the reductive and oxidative half-reactions is consistent with that previously determined for the individual EtfAB and bcd components. This includes an uncrossing of the half-potentials of the bifurcating flavin of the EtfAB component in the course of ferredoxin-reducing catalysis, ionization of the bcd flavin semiquinone and the appearance of a charge transfer complex upon binding of the high potential acceptor crotonyl-CoA. The observed rapid-reaction rates of ferredoxin reduction are independent of [NADH], [crotonyl-CoA] and [ferredoxin], with an observed rate of ∼0.2 s-1, consistent with the observed steady-state kinetics. In enzyme-monitored turnover experiments, an approach to steady-state where the complex's flavins become reduced but no ferredoxin is generated is followed by a steady-state phase characterized by extensive ferredoxin reduction but little change in overall levels of flavin reduction. The approach to steady-state phase can be eliminated by prior reduction of the complex, in which case there is no lag in the onset of ferredoxin reduction; this is consistent with the et FAD needing to be reduced to the level of the (anionic) semiquinone for bifurcation and concomitant ferredoxin reduction to occur. Single-turnover experiments support this conclusion, with accumulation of the anionic semiquinone of the et FAD apparently required to prime the system for subsequent bifurcation and ferredoxin reduction.

Coupling Electrochemical Leaching with Solvent Extraction for Recycling Spent Lithium-Ion Batteries.

We propose coupling electrochemical leaching with solvent extraction to separate and recover Li and Co from spent lithium-ion batteries (LIBs). Electrochemical leaching occurs in the aqueous electrolyte for converting solid LiCoO2 into soluble Li+ and Co2+, in which electrons act as reductants to reduce Co(III) to Co(II). Simultaneously, solvent extraction occurs at the interface of aqueous and organic phases to separate Co2+ and Li+. By capturing and utilizing the protons from P507, leaching yields for both Co and Li exceed ∼7 times than acid leaching without solvent extraction. The extraction efficiency of Co2+ reaches 86% at 60 °C, 3.5 V, while simultaneously retaining the majority of Li+ in the H2SO4 solution. The total leaching amount was improved because the organic phase provides protons to help the leaching of Co2+, and the continuous extraction process of Co(II) maintains the low Co2+ concentration in the aqueous solution. The synergistic interaction between electrochemical leaching and solvent extraction processes significantly reduces the consumption of chemicals, enhances the utilization efficiency of protons, and simplifies the recovery process. The leaching kinetics of Li and Co both conforms well to the residue layer diffusion control model and the activation energy (Ea) values of the leaching for Li and Co are 4.03 and 7.80 kJ/mol, respectively. Lastly, the economic and environmental assessment of this process also demonstrates the advantages of this method in reducing inputs, lowering environmental pollution, and enhancing economic benefits.

DeepKINET: a deep generative model for estimating single-cell RNA splicing and degradation rates.

Messenger RNA splicing and degradation are critical for gene expression regulation, the abnormality of which leads to diseases. Previous methods for estimating kinetic rates have limitations, assuming uniform rates across cells. DeepKINET is a deep generative model that estimates splicing and degradation rates at single-cell resolution from scRNA-seq data. DeepKINET outperforms existing methods on simulated and metabolic labeling datasets. Applied to forebrain and breast cancer data, it identifies RNA-binding proteins responsible for kinetic rate diversity. DeepKINET also analyzes the effects of splicing factor mutations on target genes in erythroid lineage cells. DeepKINET effectively reveals cellular heterogeneity in post-transcriptional regulation.

Rapid miRNA detection enhanced by exponential hybridization chain reaction in graphene field-effect transistors.

Scalable electronic devices that can detect target biomarkers from clinical samples hold great promise for point-of-care nucleic acid testing, but still cannot achieve the detection of target molecules at an attomolar range within a short timeframe (<1 h). To tackle this daunting challenge, we integrate graphene field-effect transistors (GFETs) with exponential target recycling and hybridization chain reaction (TRHCR) to detect oligonucleotides (using miRNA as a model disease biomarker), achieving a detection limit of 100 aM and reducing the sensing time by 30-fold, from 15 h to 30 min. In contrast to traditional linear TRHCR, our exponential TRHCR enables the target miRNA to initiate an autocatalytic system with exponential kinetics, significantly accelerating the reaction speed. The resulting reaction products, long-necked double-stranded polymers with a negative charge, are effectively detected by the GFET through chemical gating, leading to a shift in the Dirac voltage. Therefore, by monitoring the magnitude of this voltage shift, the target miRNA is quantified with high sensitivity. Consequently, our approach successfully detects 22-mer miRNA at concentrations as low as 100 aM in human serum samples, achieving the desired short timeframe of 30 min, which is congruent with point-of-care testing, and demonstrates superior specificity against single-base mismatched interfering oligonucleotides.