Advancements in Brain Research: The In Vivo/In Vitro Electrochemical Detection of Neurochemicals.

Neurochemicals, crucial for nervous system function, influence vital bodily processes and their fluctuations are linked to neurodegenerative diseases and mental health conditions. Monitoring these compounds is pivotal, yet the intricate nature of the central nervous system poses challenges. Researchers have devised methods, notably electrochemical sensing with micro-nanoscale electrodes, offering high-resolution monitoring despite low concentrations and rapid changes. Implantable sensors enable precise detection in brain tissues with minimal damage, while microdialysis-coupled platforms allow in vivo sampling and subsequent in vitro analysis, addressing the selectivity issues seen in other methods. While lacking temporal resolution, techniques like HPLC and CE complement electrochemical sensing's selectivity, particularly for structurally similar neurochemicals. This review covers essential neurochemicals and explores miniaturized electrochemical sensors for brain analysis, emphasizing microdialysis integration. It discusses the pros and cons of these techniques, forecasting electrochemical sensing's future in neuroscience research. Overall, this comprehensive review outlines the evolution, strengths, and potential applications of electrochemical sensing in the study of neurochemicals, offering insights into future advancements in the field.

Development of a multi-needle fiberoptic Raman spectroscopy technique for simultaneous multi-site deep tissue Raman measurements in the brain.

We report on the development of a multi-needle fiberoptic Raman spectroscopy (MNF-RS) technique for simultaneous multi-site deep Raman measurements in brain tissue. The multi-needle fiberoptic Raman probe is designed and fabricated using a number of 100 µm core diameter, aluminum-coated fibers under a coaxial laser excitation and Raman collection scheme, enabling simultaneous collection of deep tissue Raman spectra from a number of tissue sites. We have also developed a Raman retrieval algorithm based on the transformation matrix of each individual needle fiber probe projected to different pixels of a charge-coupled device (CCD) for recovering the tissue Raman spectra collected by each needle fiber probe, allowing simultaneous multi-channel detection by a single Raman spectrometer. High-quality tissue Raman spectra of different tissue types (e.g., muscle, fat, gray matter, and white matter in porcine brain) can be acquired in both the fingerprint (900-1800 cm-1) and high-wavenumber (2800-3300 cm-1) regions within sub-second times using the MNF-RS technique. We also demonstrate that by advancing the multi-needle fiberoptic Raman probe into deep porcine brain, tissue Raman spectra can be acquired simultaneously from different brain regions (e.g., cortex, thalamus, midbrain, and cerebellum). The significant biochemical differences across different brain tissues can also be distinguished, suggesting the promising potential of the MNF-RS technique for label-free neuroscience study at the molecular level.

Isotope dilution LA-ICP-MS for quantitative imaging of trace elements in mouse brain sections.

Isotope dilution (ID) analysis is considered one of the most accurate quantitative methods. However, it has not been widely applied to the quantitative imaging of trace elements in biological samples using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), mainly because of difficulties in homogeneously mixing enriched isotopes (the spike) with the sample (e.g., a tissue section). In this study, we present a novel method for the quantitative imaging of trace elements (copper and zinc) in mouse brain sections using ID-LA-ICP-MS. We used an electrospray-based coating device (ECD) to evenly distribute a known amount of the spike (65Cu and 67Zn) on the sections. The optimal conditions for this process involved evenly distributing the enriched isotopes on mouse brain sections mounted on indium tin oxide (ITO) glass slides using the ECD with the 10 mg g-1 ɑ-cyano-4-hydroxycinnamic acid (CHCA) in methanol at 80 °C. The mass of the spiked isotopes and the tissue sections on the ITO slides was calculated by weighing them on an analytical balance. Quantitative images of Cu and Zn in Alzheimer's disease (AD) mouse brain sections were obtained using ID-LA-ICP-MS. These imaging results showed that Cu and Zn concentrations in various brain regions typically ranged from 10 to 25 µg g-1 and 30-80 µg g-1, respectively. But it is worth noting that the hippocampus contained up to 50 µg g-1 of Zn, while the cerebral cortex and hippocampus had Cu contents as high as 150 µg g-1. These results were validated by acid digestion and solution analysis with ICP-MS. The novel ID-LA-ICP-MS method provides an accurate and reliable means for quantitative imaging of biological tissue sections.

Oral Orexin Receptor 2 Agonist in Narcolepsy Type 1.

BACKGROUND: Narcolepsy type 1 is caused by severe loss or lack of brain orexin neuropeptides. METHODS: We conducted a phase 2, randomized, placebo-controlled trial of TAK-994, an oral orexin receptor 2-selective agonist, in patients with narcolepsy type 1. Patients with confirmed narcolepsy type 1 according to clinical criteria were randomly assigned to receive twice-daily oral TAK-994 (30 mg, 90 mg, or 180 mg) or placebo. The primary end point was the mean change from baseline to week 8 in average sleep latency (the time it takes to fall asleep) on the Maintenance of Wakefulness Test (range, 0 to 40 minutes; normal ability to stay awake, ≥20 minutes). Secondary end points included the change in the Epworth Sleepiness Scale (ESS) score (range, 0 to 24, with higher scores indicating greater daytime sleepiness; normal, <10) and the weekly cataplexy rate. RESULTS: Of the 73 patients, 17 received TAK-994 at a dose of 30 mg twice daily, 20 received 90 mg twice daily, 19 received 180 mg twice daily, and 17 received placebo. The phase 2 trial and an extension trial were terminated early owing to hepatic adverse events. Primary end-point data were available for 41 patients (56%); the main reason for missing data was early trial termination. Least-squares mean changes to week 8 in average sleep latency on the MWT were 23.9 minutes in the 30-mg group, 27.4 minutes in the 90-mg group, 32.6 minutes in the 180-mg group, and -2.5 minutes in the placebo group (difference vs. placebo, 26.4 minutes in the 30-mg group, 29.9 minutes in the 90-mg group, and 35.0 minutes the 180-mg group; P<0.001 for all comparisons). Least-squares mean changes to week 8 in the ESS score were -12.2 in the 30-mg group, -13.5 in the 90-mg group, -15.1 in the 180-mg group, and -2.1 in the placebo group (difference vs. placebo, -10.1 in the 30-mg group, -11.4 in the 90-mg group, and -13.0 in the 180-mg group). Weekly incidences of cataplexy at week 8 were 0.27 in the 30-mg group, 1.14 in the 90-mg group, 0.88 in the 180-mg group, and 5.83 in the placebo group (rate ratio vs. placebo, 0.05 in the 30-mg group, 0.20 in the 90-mg group, and 0.15 in the 180-mg group). A total of 44 of 56 patients (79%) receiving TAK-994 had adverse events, most commonly urinary urgency or frequency. Clinically important elevations in liver-enzyme levels occurred in 5 patients, and drug-induced liver injury meeting Hy's law criteria occurred in 3 patients. CONCLUSIONS: In a phase 2 trial involving patients with narcolepsy type 1, an orexin receptor 2 agonist resulted in greater improvements on measures of sleepiness and cataplexy than placebo over a period of 8 weeks but was associated with hepatotoxic effects. (Funded by Takeda Development Center Americas; TAK-994-1501 and TAK-994-1504 ClinicalTrials.gov numbers, NCT04096560 and NCT04820842.).

Validating MALDI-IMS Feasibility in Ex Vivo Brain Slices.

Matrix-assisted laser desorption ionization imaging mass spectrometry (MALDI-IMS) generates unique mass spectra in X/Y coordinates across a tissue sample, thus allowing for the spatial detection and relative quantification of biologic compounds in situ. The soft ionization of MALDI-IMS makes it an ideal technique for high-resolution imaging of complex lipid species. Lipid-based spatial chemical maps derived from MALDI-IMS provide critical insight into the unique molecular profiles of a variety of neurologic diseases. Ex vivo brain slice preparations are a prominent alternative to in vivo animal models for studying many different neurologic conditions. For the first time, we present a feasible protocol for achieving reproducible lipidomic MALDI-IMS data from ex vivo rat brain slices and provide evidence that ex vivo brain slices maintain spatiochemical lipidomic profiles representative of an intact whole brain. We conducted a methods comparison assessing the lipid profiles within the neocortex, striatum, and corpus callosum between coronal sections taken from ex vivo brain slices and the current gold standard tissue preparation method, fresh frozen whole brains. For the first time we demonstrate a technique by which 400 µm ex vivo brain slices can be extracted from an imaging chamber and prepared for MALDI-IMS in a way that preserves their lipidomic integrity. We demonstrate the feasibility of MALDI-IMS in ex vivo brain slices and provide a roadmap for MALDI-IMS utilization in uncharted neuroscience fields.

Boldness and physiological variation in round goby populations along their Baltic Sea invasion front.

The round goby (Neogobius melanostomus) is a fish native to the Ponto-Caspian region that is highly invasive through freshwater and brackish habitats in northern Europe and North America. Individual behavioural variation appears to be an important factor in their spread, for example a round goby's personality traits can influence their dispersal tendency, which may also produce variation in the behavioral composition of populations at different points along their invasion fronts. To further analyze the drivers of behavioral variation within invasive round goby populations, we focused on two populations along the Baltic Sea invasion front with closely comparable physical and community characteristics. Specifically, this study measured personality within a novel environment and predator response context (i.e., boldness), and directly analyzed links between individuals' personality traits and their physiological characteristics and stress responses (i.e., blood cortisol and lactate, brain neurotransmitters). In contrast to previous findings, the more recently established population had similar activity levels but were less bold in response to a predator cue than the older population, which suggests that behavioral compositions within our study populations may be more driven by local environmental conditions rather than being a result of personality-biased dispersal. Furthermore, we found that both populations showed similar physiological stress responses, and there also appeared to be no detectable relationship between physiological parameters and behavioral responses to predator cues. Instead, body size and body condition were important factors influencing individual behavioral responses. Overall, our results reinforce the importance of boldness traits as a form of phenotypic variation in round goby populations in the Baltic Sea. We also highlight the importance of these traits for future studies specifically testing for effects of invasion processes on phenotypic variation in the species. Nonetheless, our results also highlight that the physiological mechanisms underpinning behavioural variation in these populations remain unclear.

Influence of Residual Quadrupolar Interaction on Quantitative Sodium Brain Magnetic Resonance Imaging of Patients With Multiple Sclerosis.

OBJECTIVES: The purpose of this work was to evaluate the influence of residual quadrupolar interaction on the determination of human brain apparent tissue sodium concentrations (aTSCs) using quantitative sodium magnetic resonance imaging ( 23 Na MRI) in healthy controls (HCs) and patients with multiple sclerosis (MS). Especially, it was investigated if the more detailed examination of residual quadrupolar interaction effects enables further analysis of the observed 23 Na MRI signal increase in MS patients. MATERIALS AND METHODS: 23 Na MRI with a 7 T MR system was performed on 21 HC and 50 MS patients covering all MS subtypes (25 patients with relapsing-remitting MS, 14 patients with secondary progressive MS, and 11 patients with primary progressive MS) using 2 different 23 Na pulse sequences for quantification: a commonly used standard sequence (aTSC Std ) as well as a sequence with shorter excitation pulse length and lower flip angle for minimizing signal loss resulting from residual quadrupolar interactions (aTSC SP ). Apparent tissue sodium concentration was determined using the same postprocessing pipeline including correction of the receive profile of the radiofrequency coil, partial volume correction, and relaxation correction. Spin dynamic simulations of spin-3/2 nuclei were performed to aid in the understanding of the measurement results and to get deeper insight in the underlying mechanisms. RESULTS: In normal-appearing white matter (NAWM) of HC and all MS subtypes, the aTSC SP values were approximately 20% higher than the aTSC Std values ( P < 0.001). In addition, the ratio aTSC SP /aTSC Std was significantly higher in NAWM than in normal-appearing gray matter (NAGM) for all subject cohorts ( P < 0.002). In NAWM, aTSC Std values were significantly higher in primary progressive MS compared with HC ( P = 0.01) as well as relapsing-remitting MS ( P = 0.03). However, in contrast, no significant differences between the subject cohorts were found for aTSC SP . Spin simulations assuming the occurrence of residual quadrupolar interaction in NAWM were in good accordance with the measurement results, in particular, the ratio aTSC SP /aTSC Std in NAWM and NAGM. CONCLUSIONS: Our results showed that residual quadrupolar interactions in white matter regions of the human brain have an influence on aTSC quantification and therefore must be considered, especially in pathologies with expected microstructural changes such as loss of myelin in MS. Furthermore, the more detailed examination of residual quadrupolar interactions may lead to a better understanding of the pathologies themselves.

Multi-Spatiotemporal Probing of Neurochemical Events by Advanced Electrochemical Sensing Methods.

Neurochemical events involving biosignals of different time and space dimensionalities constitute the complex basis of neurological functions and diseases. In view of this fact, electrochemical measurements enabling real-time quantification of neurochemicals at multiple levels of spatiotemporal resolution can provide informative clues to decode the molecular networks bridging vesicles and brains. This Minireview focuses on how scientific questions regarding the properties of single vesicles, neurotransmitter release kinetics, interstitial neurochemical dynamics, and multisignal interconnections in vivo have driven the design of electrochemical nano/microsensors, sensing interface engineering, and signal/data processing. An outlook for the future frontline in this realm will also be provided.

Enhanced imaging of endogenous metabolites by negative ammonia assisted DESI/PI mass spectrometry.

In this work, endogenous metabolites in mouse brain tissue were imaged by negative desorption electrospray ionization (DESI), ammonia assisted DESI (aa-DESI), DESI/post-photoionization (DESI/PI), and ammonia assisted DESI/PI (aa-DESI/PI) mass spectrometry imaging (MSI) strategies. The combined effect of ammonia additive and post-photoionization was found to play an important role in the enhancement of sensitivity and coverage for endogenous analytes under ambient conditions. Compared with DESI, aa-DESI/PI can provide increased signal intensities for metabolites up to 37.1-fold, as well as the imaging of nine more small metabolites (m/z < 350) (26 for aa-DESI/PI and 17 for DESI) in mouse brain tissue. The results of Pearson correlation analysis and KEGG pathway analysis showed that the enhanced imaging strategy of aa-DESI/PI can facilitate the study of endogenous metabolic pathways and molecular networks. Moreover, the imaging results of mouse tumor tissue demonstrated the promising application of aa-DESI/PI in tumor research.

Mass Spectrometry for the Advancement of Lipid Analysis in Alzheimer's Research.

Recent technical advances in mass spectrometry, as applied to the analytical chemistry of lipid molecules, enable the simultaneous detection of the multiplicity of lipid complex species present in the human brain. This, in combination with quantitative studies carried out in plasma samples, helps to identify disease biomarkers including for Alzheimer's disease (AD). Mass spectrometry imaging (MSI) is particularly powerful for the anatomical localization of lipids in brain slices, identifying lipid modifications in postmortem frozen samples from AD patients.Human brain tissues are sectioned in a cryostat and then covered with a chemical matrix, such as mercaptobenzothiazole (MBT) or α-cyano-4-hydroxycinnamic acid (CHCA), to ionize the lipid molecules either by sublimation or by spraying. We describe the use of matrix-assisted laser desorption ionization (MALDI) in an LTQ-Orbitrap-XL mass spectrometer to scan brain tissue slices with high spatial resolution, analyzing 50 µm cell layers. The lipid spectra obtained for each pixel are transformed to color-coded intensity maps of hundreds of lipid species included those within a single tissue slice.

In-depth mapping of protein localizations in whole tissue by micro-scaffold assisted spatial proteomics (MASP).

Accurate, in-depth mapping of proteins on whole-tissue levels provides comprehensive insights into the spatially-organized regulatory processes/networks in tissues, but is challenging. Here we describe a micro-scaffold assisted spatial proteomics (MASP) strategy, based on spatially-resolved micro-compartmentalization of tissue using a 3D-printed micro-scaffold, capable of mapping thousands of proteins across a whole-tissue slice with excellent quantitative accuracy/precision. The pipeline includes robust tissue micro-compartmentalization with precisely-preserved spatial information, reproducible procurement and preparation of the micro-specimens, followed by sensitive LC-MS analysis and map generation by a MAsP app. The mapping accuracy was validated by comparing the MASP-generated maps of spiked-in peptides and brain-region-specific markers with known patterns, and by correlating the maps of the two protein components of the same heterodimer. The MASP was applied in mapping >5000 cerebral proteins in the mouse brain, encompassing numerous important brain markers, regulators, and transporters, where many of these proteins had not previously been mapped on the whole-tissue level.

IR-MALDI Mass Spectrometry Imaging with Plasma Post-Ionization of Nonpolar Metabolites.

Ambient mass spectrometry imaging (MSI) methods come with the advantage of visualizing biomolecules from tissues with no or minimal sample preparation and operation under atmospheric-pressure conditions. Similar to all other MSI methodologies, however, ambient MSI modalities suffer from a pronounced bias toward either polar or nonpolar analytes due to the underlying desorption and ionization mechanisms of the ion source. In this study, we present the design, construction, testing, and application of an in-capillary dielectric barrier discharge (DBD) module for post-ionization of neutrals desorbed by an ambient infrared matrix-assisted laser desorption/ionization (IR-MALDI) MSI source. We demonstrate that the DBD device enhances signal intensities of nonpolar compounds by up to 104 compared to IR-MALDI without affecting transmission of IR-MALDI ions. This allows performing MSI experiments of mouse tissue and Danaus plexippus caterpillar tissue sections, visualizing the distribution of sterols, fatty acids, monoglycerides, and diglycerides that are not detected in IR-MALDI MSI experiments. The pronounced signal enhancement due to IR-MALDI-DBD compared to IR-MALDI MSI enables mapping of nonpolar analytes with pixel resolutions down to 20 µm in mouse brain tissue and to discern the spatial distribution of sterol lipids characteristic for histological regions of D. plexippus.

Trial of Deferiprone in Parkinson's Disease.

BACKGROUND: Iron content is increased in the substantia nigra of persons with Parkinson's disease and may contribute to the pathophysiology of the disorder. Early research suggests that the iron chelator deferiprone can reduce nigrostriatal iron content in persons with Parkinson's disease, but its effects on disease progression are unclear. METHODS: We conducted a multicenter, phase 2, randomized, double-blind trial involving participants with newly diagnosed Parkinson's disease who had never received levodopa. Participants were assigned (in a 1:1 ratio) to receive oral deferiprone at a dose of 15 mg per kilogram of body weight twice daily or matched placebo for 36 weeks. Dopaminergic therapy was withheld unless deemed necessary for symptom control. The primary outcome was the change in the total score on the Movement Disorder Society-sponsored revision of the Unified Parkinson's Disease Rating Scale (MDS-UPDRS; range, 0 to 260, with higher scores indicating more severe impairment) at 36 weeks. Secondary and exploratory clinical outcomes at up to 40 weeks included measures of motor and nonmotor disability. Brain iron content measured with the use of magnetic resonance imaging was also an exploratory outcome. RESULTS: A total of 372 participants were enrolled; 186 were assigned to receive deferiprone and 186 to receive placebo. Progression of symptoms led to the initiation of dopaminergic therapy in 22.0% of the participants in the deferiprone group and 2.7% of those in the placebo group. The mean MDS-UPDRS total score at baseline was 34.3 in the deferiprone group and 33.2 in the placebo group and increased (worsened) by 15.6 points and 6.3 points, respectively (difference, 9.3 points; 95% confidence interval, 6.3 to 12.2; P<0.001). Nigrostriatal iron content decreased more in the deferiprone group than in the placebo group. The main serious adverse events with deferiprone were agranulocytosis in 2 participants and neutropenia in 3 participants. CONCLUSIONS: In participants with early Parkinson's disease who had never received levodopa and in whom treatment with dopaminergic medications was not planned, deferiprone was associated with worse scores in measures of parkinsonism than those with placebo over a period of 36 weeks. (Funded by the European Union Horizon 2020 program; FAIRPARK-II ClinicalTrials.gov number, NCT02655315.).

Real-Time Dynamic Collection of Hippocampal Extracellular Fluid from Conscious Rats Using a Microdialysis System.

A variety of central nervous system (CNS) diseases are associated with changes in the composition of hippocampal extracellular fluid (HECF). However, difficulty in obtaining HECF in real time from conscious rats has long restricted the evaluation of CNS disease progression and the effectiveness of ethnomedicine therapy. Encouragingly, a brain microdialysis technique can be used for continuous sampling with the advantages of dynamic observation, quantitative analysis, and a small sampling size. This allows the monitoring of changes in the extracellular fluid content for compounds from traditional herbs and their metabolites in the brain of living animals. The aim of this study was thus to accurately implant a cerebrospinal fluid microdialysis probe into the hippocampal region of Sprague Dawley (SD) rats with a three-dimensional brain stereotaxic apparatus, cutting off molecular weights greater than 20 kDa. The high-quality HECF was then obtained from conscious rats using a microdialysis sampling control system with an adjustable sampling rate from 2.87 nL/min - 2.98 mL/min. In conclusion, our protocol provides an efficient, rapid, and dynamic method to obtain HECF in awake rats with the help of microdialysis technology, which provides us with unlimited possibilities to further explore the pathogenesis of CNS-related diseases and evaluate drug efficacy.

Association between ageing, brain chemistry and white matter volume revealed with complementary MRI and FTIR brain imaging.

Magnetic resonance imaging (MRI) is the gold standard method to study brain anatomy in vivo. Using MRI, subtle alterations to white matter structures in the brain are observed prior to cognitive decline associated with the ageing process, and neurodegenerative diseases such as Alzheimer's disease. Detection of such alterations provides hope for early clinical diagnosis. While MRI is essential to detect subtle alterations to brain structure in vivo, the technique is less suited to study and image the distribution of biochemical markers within specific brain structures. Consequently, the chemical changes that drive, or are associated with MRI-detectable alterations to white matter are not well understood. Herein, we describe (to the best of our knowledge) the first application of a complementary imaging approach that incorporates in vivo MRI with ex vivo Fourier transform infrared (FTIR) spectroscopic imaging on the same brain tissue. The combined workflow is used to detect and associate markers of altered biochemistry (FTIR) with anatomical changes to brain white matter (MRI). We have applied this combination of techniques to the senescence accelerated murine prone strain 8 (SAMP8) mouse model (n = 6 animals in each group, analysed across two ageing time points, 6 and 12 months). The results have demonstrated alterations to lipid composition and markers of disturbed metabolism during ageing are associated with loss of white matter volume.

Structures of α-synuclein filaments from human brains with Lewy pathology.

Parkinson's disease (PD) is the most common movement disorder, with resting tremor, rigidity, bradykinesia and postural instability being major symptoms1. Neuropathologically, it is characterized by the presence of abundant filamentous inclusions of α-synuclein in the form of Lewy bodies and Lewy neurites in some brain cells, including dopaminergic nerve cells of the substantia nigra2. PD is increasingly recognised as a multisystem disorder, with cognitive decline being one of its most common non-motor symptoms. Many patients with PD develop dementia more than 10 years after diagnosis3. PD dementia (PDD) is clinically and neuropathologically similar to dementia with Lewy bodies (DLB), which is diagnosed when cognitive impairment precedes parkinsonian motor signs or begins within one year from their onset4. In PDD, cognitive impairment develops in the setting of well-established PD. Besides PD and DLB, multiple system atrophy (MSA) is the third major synucleinopathy5. It is characterized by the presence of abundant filamentous α-synuclein inclusions in brain cells, especially oligodendrocytes (Papp-Lantos bodies). We previously reported the electron cryo-microscopy structures of two types of α-synuclein filament extracted from the brains of individuals with MSA6. Each filament type is made of two different protofilaments. Here we report that the cryo-electron microscopy structures of α-synuclein filaments from the brains of individuals with PD, PDD and DLB are made of a single protofilament (Lewy fold) that is markedly different from the protofilaments of MSA. These findings establish the existence of distinct molecular conformers of assembled α-synuclein in neurodegenerative disease.

Deep learning predicts DNA methylation regulatory variants in the human brain and elucidates the genetics of psychiatric disorders.

There is growing evidence for the role of DNA methylation (DNAm) quantitative trait loci (mQTLs) in the genetics of complex traits, including psychiatric disorders. However, due to extensive linkage disequilibrium (LD) of the genome, it is challenging to identify causal genetic variations that drive DNAm levels by population-based genetic association studies. This limits the utility of mQTLs for fine-mapping risk loci underlying psychiatric disorders identified by genome-wide association studies (GWAS). Here we present INTERACT, a deep learning model that integrates convolutional neural networks with transformer, to predict effects of genetic variations on DNAm levels at CpG sites in the human brain. We show that INTERACT-derived DNAm regulatory variants are not confounded by LD, are concentrated in regulatory genomic regions in the human brain, and are convergent with mQTL evidence from genetic association analysis. We further demonstrate that predicted DNAm regulatory variants are enriched for heritability of brain-related traits and improve polygenic risk prediction for schizophrenia across diverse ancestry samples. Finally, we applied predicted DNAm regulatory variants for fine-mapping schizophrenia GWAS risk loci to identify potential novel risk genes. Our study shows the power of a deep learning approach to identify functional regulatory variants that may elucidate the genetic basis of complex traits.

Enhanced Sensing Performance of a Microchannel-Based Electrochemiluminescence Biosensor for Adenosine Triphosphate via a dsDNA Superstructure Amplification Strategy.

The sensing performance of a microchannel-based electrochemiluminescence (ECL) biosensor is related to the change ratio of charge density on the surface of microchannels caused by a target recognition reaction. In this study, adenosine triphosphate (ATP) served as a model target. The dsDNA superstructures containing a capture probe (CP, containing an ATP aptamer sequence) and alternating units of ssDNA probes of P1 and P2, CP/(P1/P2)n, were grafted onto the inner wall of microchannels first. The CP in dsDNA superstructures captured ATP molecules, causing the release of dsDNA fragments containing alternating units of P1 and P2, (P1/P2)n. The target recognition reaction significantly changed the charge density of microchannels, which altered the ECL intensity of the (1,10-phenanthroline)ruthenium(II)/tripropylamine system in the reporting interface. The ECL intensity of the constructed system had a linear relationship with the logarithm of ATP concentration ranging from 1 fM to 100 pM with a detection limit of 0.32 fM (S/N = 3). The biosensor was successfully applied to detect ATP in rat brains.