α-Synuclein Oligomer Detection with Aptamer Switch on Reduced Graphene Oxide Electrode

Chitosan-enhanced sensitivity of mercaptoundecanoic acid (MUA)- capped gold nanorod based localized surface plasmon resonance (LSPR) biosensor for detection of alpha-synuclein oligomer biomarker in parkinson's disease

Alpha-synuclein oligomers play a crucial role in the early diagnosis of Parkinson's disease (PD). In this study, a mercaptoundecanoic acid (MUA)-capped gold nanorod (GNR)-coated and chitosan (CH)-immobilized fiber optic probe has shown considerable sensitivity of its detection. The proposed U-shaped fiber optic biosensor based on localized surface plasmon resonance (LSPR) was applied to detect α-syn oligomer (OA) biomarker. By analyzing OA concentrations, the biosensor achieved a limit of detection of (LOD) 11 pM within the concentration range of 10-100 pM and the sensitivity value was found as 502.69 Δλ/RIU. Upon analysis of the CV% (coefficient of variation) and accuracy/recovery values, it is revealed that the sensor successfully fulfilled the criteria for success, displaying accuracy/recovery values within the range of 80%-120% and CV% values below 20%. This sensor presents significant advantages, including high sensitivity, specificity, and ability to detect very low concentrations of OA. In conclusion, the suggested U-shaped fiber optic biosensor has the potential to be valuable in the early detection of PD from a clinical perspective.

Biosensors for Parkinson's Disease: Where Are We Now, and Where Do We Need to Go?

Parkinson's Disease is the second most common neurological disease in the United States, yet there is no cure, no pinpointed cause, and no definitive diagnostic procedure. Parkinson's is typically diagnosed when patients present with motor symptoms such as slowness of movement and tremors. However, none of these are specific to Parkinson's, and a confident diagnosis of Parkinson's is typically only achieved when 60-80% of dopaminergic neurons are no longer functioning, at which point much of the damage to the brain is irreversible. This Perspective details ongoing efforts and accomplishments in biosensor research with the goal of overcoming these issues for Parkinson's diagnosis and care, with a focus on the potential impact of early diagnosis and associated opportunities to pinpoint a cause and a cure. We critically analyze the strengths and shortcomings of current technologies and discuss the ideal characteristics of a diagnostic technology toolbox to guide future research decisions in this space. Finally, we assess what role biosensors can play in facilitating precision medicine for Parkinson's patients.

Digital biomarkers in Parkinson's disease

Digital biomarker (DB) assessments provide objective measures of daily life tasks and thus hold promise to improve diagnosis and monitoring of Parkinson's disease (PD) patients especially those with advanced stages. Data from DB studies can be used in advanced analytics such as Artificial Intelligence and Machine Learning to improve monitoring, treatment and outcomes. Although early development of inertial sensors as accelerometers and gyroscopes in smartphones provided encouraging results, the use of DB remains limited due to lack of standards, harmonization and consensus for analytical as well as clinical validation. Accordingly, a number of clinical trials have been developed to evaluate the performance of DB vs traditional assessment tools with the goal of monitoring disease progression, improving quality of life and outcomes. Herein, we update current evidence on the use of DB in PD and highlight potential benefits and limitations and provide suggestions for future research study.

Artificial Intelligence-Guided Gut-Microenvironment-Triggered Imaging Sensor Reveals Potential Indicators of Parkinson's Disease

The gut-brain axis has recently emerged as a crucial link in the development and progression of Parkinson's disease (PD). Dysregulation of the gut microbiota has been implicated in the pathogenesis of this disease, sparking growing interest in the quest for non-invasive biomarkers derived from the gut for early PD diagnosis. Herein, an artificial intelligence-guided gut-microenvironment-triggered imaging sensor (Eu-MOF@Au-Aptmer) to achieve non-invasive, accurate screening for various stages of PD is presented. The sensor works by analyzing α-Syn in the gut using deep learning algorithms. By monitoring changes in α-Syn, the sensor can predict the onset of PD with high accuracy. This work has the potential to revolutionize the diagnosis and treatment of PD by allowing for early intervention and personalized treatment plans. Moreover, it exemplifies the promising prospects of integrating artificial intelligence (AI) and advanced sensors in the monitoring and prediction of a broad spectrum of diseases and health conditions.

An α-helical peptide-based plasmonic biosensor for highly specific detection of α-synuclein toxic oligomers

BACKGROUND

α-Synuclein (αS) aggregation is the main neurological hallmark of a group of neurodegenerative disorders, collectively referred to as synucleinopathies, of which Parkinson's disease (PD) is the most prevalent. αS oligomers are elevated in the cerebrospinal fluid (CSF) of PD patients, standing as a biomarker for disease diagnosis. However, methods for early PD detection are still lacking. We have recently identified the amphipathic 22-residue peptide PSMα3 as a high-affinity binder of αS toxic oligomers. PSMα3 displayed excellent selectivity and reproducibility, binding to αS toxic oligomers with affinities in the low nanomolar range and without detectable cross-reactivity with functional monomeric αS.

RESULTS

In this work, we leveraged these PSMα3 unique properties to design a plasmonic-based biosensor for the direct detection of toxic oligomers under label-free conditions.

SIGNIFICANCE AND NOVELTY

We describe the integration of the peptide in a lab-on-a-chip plasmonic platform suitable for point-of-care measurements of αS toxic oligomers in CSF samples in real-time and at an affordable cost, providing an innovative biosensor for PD early diagnosis in the clinic.

Harnessing two-dimensional nanomaterials for diagnosis and therapy in neurodegenerative diseases: Advances, challenges and prospects

Neurodegenerative diseases (NDDs) are specific brain disorders characterized by the progressive deterioration of different motor activities as well as several cognitive functions. Current conventional therapeutic options for NDDs are limited in addressing underlying causes, delivering drugs to specific neuronal targets, and promoting tissue repair following brain injury. Due to the paucity of plausible theranostic options for NDDs, nanobiotechnology has emerged as a promising field, offering an interdisciplinary approach to create nanomaterials with high diagnostic and therapeutic efficacy for these diseases. Recently, two-dimensional nanomaterials (2D-NMs) have gained significant attention in biomedical and pharmaceutical applications due to their precise drug-loading capabilities, controlled release mechanisms, enhanced stability, improved biodegradability, and reduced cell toxicity. Although various studies have explored the diagnostic and therapeutic potential of different nanomaterials in NDDs, there is a lack of comprehensive review addressing the theranostic applications of 2D-NMs in these neuronal disorders. Therefore, this concise review aims to provide a state-of-the-art understanding of the need for these ultrathin 2D-NMs and their potential applications in biosensing and bioimaging, targeted drug delivery, tissue engineering, and regenerative medicine for NDDs.

Electrochemical DNA Cleavage Sensing for EcoRV Activity and Inhibition with an ERGO Electrode

An electrochemically reduced graphene oxide (ERGO) electrode-based electrochemical assay was developed for rapid, sensitive, and straightforward analysis of both activity and inhibition of the endonuclease EcoRV. The procedure uses a DNA substrate designed for EcoRV, featuring a double-stranded DNA (dsDNA) region labeled with methylene blue (MB) and a single-stranded DNA (ssDNA) region immobilized on the ERGO surface. The ERGO electrode, immobilized with the DNA substrate, was subsequently exposed to a sample containing EcoRV. Upon enzymatic hydrolysis, the cleaved dsDNA fragments were detached from the ERGO surface, leading to a decrease in the MB concentration near the electrode. This diminished the electron transfer efficiency for MB reduction, resulting in a decreased reduction current. This assay demonstrates excellent specificity and high sensitivity, with a limit of detection (LOD) of 9.5 × 10-3 U mL-1. Importantly, it can also measure EcoRV activity in the presence of aurintricarboxylic acid, a known inhibitor, highlighting its potential for drug discovery and clinical diagnostic applications.

Alpha-Synuclein Oligomers Driven T1-T2 Switchable Nanoprobes for Early and Accurate Diagnosis of Parkinson's Disease

The alpha-synuclein (α-syn) oligomers hold a central role in the pathology of Parkinson's disease (PD). Achieving accurate detection of α-syn oligomers in vivo presents a promising avenue for early and accurate diagnosis of PD. Magnetic resonance imaging (MRI), with non-invasion and exceptional tissue penetration, offers a potent tool for visualizing α-syn oligomers in vivo. Nonetheless, ensuring diagnostic specificity remains a formidable challenge. Herein, a novel MRI probe (ASOSN) is introduced, which encompasses highly sensitive antiferromagnetic nanoparticles functionalized with single-chain fragment variable antibodies, endowing it with the capacity for discerning recognition and binding to α-syn oligomers and triggering a switchable T1-T2 MRI signal. Significantly, ASOSN possesses the unique capability to accurately discriminate α-syn oligomers from neuroinflammation in vivo. Moreover, ASOSN facilitates the non-invasive and precise visualizing of endogenous α-syn oligomers in living systems. This innovative design heralds the development of a non-invasive visualization strategy for α-syn oligomers, marking a pivotal advancement for early and accurate diagnosis of PD.

An update on pathogenesis and clinical scenario for Parkinson's disease: diagnosis and treatment

In severe cases, Parkinson's disease causes uncontrolled movements known as motor symptoms such as dystonia, rigidity, bradykinesia, and tremors. Parkinson's disease also causes non-motor symptoms such as insomnia, constipation, depression and hysteria. Disruption of dopaminergic and non-dopaminergic neural networks in the substantia nigra pars compacta is a major cause of motor symptoms in Parkinson's disease. Furthermore, due to the difficulty of clinical diagnosis of Parkinson's disease, it is often misdiagnosed, highlighting the need for better methods of detection. Treatment of Parkinson's disease is also complicated due to the difficulties of medications passing across the blood-brain barrier. Moreover, the conventional methods fail to solve the aforementioned issues. As a result, new methods are needed to detect and treat Parkinson's disease. Improved diagnosis and treatment of Parkinson's disease can help avoid some of its devastating symptoms. This review explores how nanotechnology platforms, such as nanobiosensors and nanomedicine, have improved Parkinson's disease detection and treatment. Nanobiosensors integrate science and engineering principles to detect Parkinson's disease. The main advantages are their low cost, portability, and quick and precise analysis. Moreover, nanotechnology can transport medications in the form of nanoparticles across the blood-brain barrier. However, because nanobiosensors are a novel technology, their use in biological systems is limited. Nanobiosensors have the potential to disrupt cell metabolism and homeostasis, changing cellular molecular profiles and making it difficult to distinguish sensor-induced artifacts from fundamental biological phenomena. In the treatment of Parkinson's disease, nanoparticles, on the other hand, produce neurotoxicity, which is a challenge in the treatment of Parkinson's disease. Techniques must be developed to distinguish sensor-induced artifacts from fundamental biological phenomena and to reduce the neurotoxicity caused by nanoparticles.

Advances in graphene-based nanoplatforms and their application in Parkinson's disease

Graphene and GBNs offer diverse PD management modalities by targeting neurodegeneration, exerting regenerative properties and their use as carriers, biosensors, and imaging agents.

Detection and modulation of neurodegenerative processes using graphene-based nanomaterials: Nanoarchitectonics and applications

Neurodegenerative disorders (NDDs) are caused by progressive loss of functional neurons following the aggregation and fibrillation of proteins in the central nervous system. The incidence rate continues to rise alarmingly worldwide, particularly in aged population, and the success of treatment remains limited to symptomatic relief. Graphene nanomaterials (GNs) have attracted immense interest on the account of their unique physicochemical and optoelectronic properties. The research over the past two decades has recognized their ability to interact with aggregation-prone neuronal proteins, regulate autophagy and modulate the electrophysiology of neuronal cells. Graphene can prevent the formation of higher order protein aggregates and facilitate the clearance of such deposits. In this review, after highlighting the role of protein fibrillation in neurodegeneration, we have discussed how GN-protein interactions can be exploited for preventing neurodegeneration. A comprehensive understanding of such interactions would contribute to the exploration of novel modalities for controlling neurodegenerative processes.

Fabrication and Functionalisation of Nanocarbon-Based Field-Effect Transistor Biosensors

Nanocarbon-based field-effect transistor (NC-FET) biosensors are at the forefront of future diagnostic technology. By integrating biological molecules with electrically conducting carbon-based platforms, high sensitivity real-time multiplexed sensing is possible. Combined with their small footprint, portability, ease of use, and label-free sensing mechanisms, NC-FETs are prime candidates for the rapidly expanding areas of point-of-care testing, environmental monitoring and biosensing as a whole. In this review we provide an overview of the basic operational mechanisms behind NC-FETs, synthesis and fabrication of FET devices, and developments in functionalisation strategies for biosensing applications.

The Neurodegenerative Elderly Syndrome (NES) hypothesis: Alzheimer and Parkinson are two faces of the same disease

Increasing evidence suggests that Alzheimer's disease (AD) and Parkinson's disease (PD) share monoamine and alpha-synuclein (αSyn) dysfunctions, often beginning years before clinical manifestations onset. The triggers for these impairments and the causes leading these early neurodegenerative processes to become AD or PD remain unclear. We address these issues by proposing a radically new perspective to frame AD and PD: they are different manifestations of one only disease we call "Neurodegenerative Elderly Syndrome (NES)". NES goes through three phases. The seeding stage, which starts years before clinical signs, and where the part of the brain-body affected by the initial αSyn and monoamine dysfunctions, influences the future possible progression of NES towards PD or AD. The compensatory stage, where the clinical symptoms are still silent thanks to compensatory mechanisms keeping monoamine concentrations homeostasis. The bifurcation stage, where NES becomes AD or PD. We present recent literature supporting NES and discuss how this hypothesis could radically change the comprehension of AD and PD comorbidities and the design of novel system-level diagnostic and therapeutic actions.

Role of MicroRNAs, Aptamers in Neuroinflammation and Neurodegenerative Disorders

Exploring the microRNAs and aptamers for their therapeutic role as biological drugs has expanded the horizon of its applicability against various human diseases, explicitly targeting the genetic materials. RNA-based therapeutics are widely being explored for the treatment and diagnosis of multiple diseases, including neurodegenerative disorders (NDD). Latter includes microRNA, aptamers, ribozymes, and small interfering RNAs (siRNAs), which control the gene expression mainly at the transcriptional strata. One RNA transcript translates into different protein types; hence, therapies targeted at the transcriptional sphere may have prominent and more extensive effects than alternative therapeutics. Unlike conventional gene therapy, RNAs, upon delivery, can either altogether abolish or alter the synthesis of the protein of interest, therefore, regulating their activities in a controlled and diverse manner. NDDs like Alzheimer's disease, Parkinson's disease, Huntington's disease, multiple sclerosis, Prion disease, and others are characterized by deposition of misfolded protein such as amyloid-ß, tau, α-synuclein, huntingtin and prion proteins. Neuroinflammation, one of the perquisites for neurodegeneration, is induced during neurodegenerative pathogenesis. In this review, we discuss microRNAs and aptamers' role as two different RNA-based approaches for their unique ability to regulate protein production at the transcription level, hence offering many advantages over other biologicals. The microRNA acts either by alleviating the malfunctioning RNA expression or by working as a replacement to lost microRNA. On the contrary, aptamer act as a chemical antibody and forms an aptamer-target complex.

A FRET-based aptasensor for the detection of α-synuclein oligomers as biomarkers of Parkinson's disease

Soluble oligomers of α-synuclein (α-syn) are known to be responsible for neuronal death in the early stages of Parkinson's disease (PD). Thus, the development of a simple, rapid, and inexpensive method for the detection of α-syn oligomers can help PD diagnosis before irreversible damage to the brain tissue occurs. The present study is aimed at developing a FRET-based aptasensor for the selective and sensitive detection of α-syn oligomers. Herein, FAM-labeled aptamer adsorption on graphene oxide (GO) resulted in fluorescence quenching of FAM. The binding of α-syn oligomers to the aptamer led to the recovery of the fluorescence intensity. Under optimized conditions, the developed biosensor showed two linear response ranges from 10-100 nM and 250 nM to 2 μM in α-syn oligomer detection. The limit of detection (LOD) and limit of quantification (LOQ) were calculated to be 6.3 nM and 19.3 nM, respectively. Furthermore, the performance of the sensing platform in the detection of the target analyte in biological matrices was demonstrated by the assay of α-syn oligomers in spiked human saliva samples. According to the obtained results, this sensing platform has a good performance for α-syn oligomer detection and it can be considered as a promising candidate for the early diagnosis of PD.

Current Progress in Aptasensor for Ultra-Low Level Monitoring of Parkinson's Disease Biomarkers

In today's world, Parkinson's disease (PD) has been introduced as a long-term degenerative disorder of the central nervous system which mainly affects approximately more than ten million people worldwide. The vast majority of diagnostic methods for PD have operated based on conventional sensing platforms, while the traditional laboratory tests are not efficient for diagnosis of PD in the early stage due to symptoms of this common neurodegenerative syndrome starting slowly. The advent of the aptasensor has revolutionized the early-stage diagnosis of PD by measuring related biomarkers due to the myriad advantages of originating from aptamers which can be able to sensitive and selective capture various types of related biomarkers. The progress of numerous sensing platforms and methodologies in terms of biosensors based on aptamer application for PD diagnosis has revealed promising results. In this review, we present the latest developments in myriad types of aptasensors for the determination of related PD biomarkers. Working strategies, advantages and limitations of these sensing approaches are also mentioned, followed by prospects and challenges.

Electrochemical Aptasensors for Parkinson's Disease Biomarkers Detection

BACKGROUND

Biomarkers are characteristic molecules that can be measured as indicators of biological process status or condition, exhibiting special relevance in Parkinson's Disease (PD). This disease is a chronic neurodegenerative disorder very difficult to study given the site of pathology and due to a clinical phenotype that fluctuates over time. Currently there is no definitive diagnostic test, thus clinicians hope that the detection of crucial biomarkers will help to the symptomatic and presymptomatic diagnostics and providing surrogate endpoints to demonstrate the clinical efficacy of new treatments.

METHODS

Electrochemical aptasensors are excellent analytical tools that are used in the detection of PD biomarkers, as they are portable, easy to use, and perform real-time analysis.

RESULTS

In this review, we discuss the most important clinical biomarkers for PD, highlighting their physiological role and function in the disease. Herein, we review for the first time innovative aptasensors for the detection of current potential PD biomarkers based on electrochemical techniques and discuss future alternatives, including ideal analytical platforms for point-of-care diagnostics.

CONCLUSION

These new tools will be critical not only in the discovery of sensitive, specific, and reliable biomarkers of preclinical PD, but also in the development of tests that can assist in the early detection and differential diagnosis of parkinsonian disorders and in monitoring disease progression. Various methods for fixing aptamers onto the sensor surfaces, enabling quantitative and specific PD biomarker detection present in synthetic and clinical samples, will also be discussed.

Comparison of Different Platform Immunoassays for the Measurement of Plasma Alpha-Synuclein in Parkinson's Disease Patients

Background:

The identification of reliable biomarkers in Parkinson’s disease (PD) would provide much needed diagnostic accuracy, a means of monitoring progression, objectively measuring treatment response, and potentially allowing patient stratification within clinical trials. Whilst the assessment of total alpha-synuclein in biofluids has been identified as a promising biomarker, conflicting trends in these levels across patient plasma samples relative to controls has limited its use. Different commercially available assay platforms that have been used to measure alpha-synuclein may contribute to different study outcomes.

Objective:

To compare different platform immunoassays for the measurement of total alpha-synuclein using the same plasma samples from 49 PD patients and 47 controls.

Methods:

Total plasma alpha-synuclein concentrations were assessed using the BioLegend, MesoScale Discovery, and Quanterix platform in plasma samples from PD patients and matched controls.

Results:

A significant increase in total plasma alpha-synuclein was observed in PD patients using the Biolegend (10%), Mesoscale Discovery (13%) and Quanterix (39%) assays. The Mesoscale Discovery and Quanterix assays showed the strongest correlations (r = 0.78, p < 0.0001) with each other, whilst the Quanterix platform demonstrated the lowest variation and highest effect size. Inclusion of age, sex and hemoglobin levels as covariates in the analysis of total alpha-synuclein improved the ability of all three immunoassays to detect a significant difference between patients and controls.

Conclusion:

All three immunoassays were sensitive enough to detect group level differences between PD patients and controls, with the largest effect size observed with the Quanterix assay. These results may help inform assay choices in ongoing clinical trials.

Transition metal dichalcogenides to optimize the performance of peptide-imprinted conductive polymers as electrochemical sensors

Molecularly imprinted polymer (MIP)-based electrochemical sensors for the protein α-synuclein (a marker for Parkinson's disease) were developed using a peptide epitope from the protein. MIPs doped with various concentrations and species of transition metal dichalcogenides (TMDs) to enhance conductivity were electropolymerized with and without template molecules. The current during the electropolymerization was compared with that associated with the electrochemical response (at 0.24~0.29 V vs. ref. electrode) to target peptide molecules in the finished sensor. We found that this relationship can aid in the rational design of conductive MIPs for the recognition of biomarkers in biological fluids. The sensing range and limit of detection of TMD-doped imprinted poly(AN-co-MSAN)-coated electrodes were 0.001-100 pg/mL and 0.5 fg/mL (SNR = 3), respectively. To show the potential applicability of the MIP electrochemical sensor, cell culture medium from PD patient-specific midbrain organoids generated from induced pluripotent stem cells was analyzed. α-Synuclein levels were found to be significantly reduced in the organoids from PD patients, compared to those generated from age-matched controls. The relative standard deviation and recovery are less than 5% and 95-115%, respectively. Preparation of TMD-doped α-synuclein (SNCA) peptide-imprinted poly(AN-co-MSAN)-coated electrodes.

Quantifying misfolded protein oligomers as drug targets and biomarkers in Alzheimer and Parkinson diseases

Protein misfolding and aggregation are characteristic of a wide range of neurodegenerative disorders, including Alzheimer and Parkinson diseases. A hallmark of these diseases is the aggregation of otherwise soluble and functional proteins into amyloid aggregates. Although for many decades such amyloid deposits have been thought to be responsible for disease progression, it is now increasingly recognized that the misfolded protein oligomers formed during aggregation are, instead, the main agents causing pathological processes. These oligomers are transient and heterogeneous, which makes it difficult to detect and quantify them, generating confusion about their exact role in disease. The lack of suitable methods to address these challenges has hampered efforts to investigate the molecular mechanisms of oligomer toxicity and to develop oligomer-based diagnostic and therapeutic tools to combat protein misfolding diseases. In this Review, we describe methods to quantify misfolded protein oligomers, with particular emphasis on diagnostic applications as disease biomarkers and on therapeutic applications as target biomarkers. The development of these methods is ongoing, and we discuss the challenges that remain to be addressed to establish measurement tools capable of overcoming existing limitations and to meet present needs.

Distinguishing normal and aggregated alpha-synuclein interaction on gold nanorod incorporated zinc oxide nanocomposite by electrochemical technique

Misfolding and accumulation of the protein alpha synuclein in the brain cells characterize Parkinson's disease (PD). Electrochemical based aluminum interdigitated electrodes (ALIDEs) was fabricated by using conventional photolithography method and modified the surfaces with zinc oxide and gold nanorod by using spin coating method for the analysis of PD protein biomarker. The device surface modified with gold nanorod of 25 nm diameter was used. The bare devices and the surface modified devices were characterized by Scanning Electron Microscope, 3D-Profilometer, Atomic Force Microscope and high-power microscope. The above measurement was also performed to measure the interaction of antibody with aggregated alpha-synuclein for normal, aggregated and aggregated alpha synuclein in human serum and distinguished against 3 control proteins (PARK1, DJ-1 and Factor IX). The detection limit for normal alpha synuclein was 1 f. with the sensitivity of 1 f. on a linear regression (R² = 0.9759). The detection limit for aggregated alpha synuclein was 10 aM with the sensitivity of 1 aM on a linear regression (R² = 0.9797). Also, the detection limit of aggregated alpha synuclein in serum was 10 aM with the sensitivity of 1 aM on a linear regression (R² = 0.9739). These results however indicate that, serum has only minimal amount of alpha synuclein.

Epitope imprinting of alpha-synuclein for sensing in Parkinson's brain organoid culture medium

Parkinson's disease (PD) is a progressive nervous system disorder that affects movement, whose early signs may be mild and unnoticed. α-Synuclein has been identified as the major component of Lewy bodies and Lewy neurites, which are the characteristic proteinaceous deposits that are the hallmarks of PD. In this work, three alpha-synuclein peptides were synthesized as templates for the molecular imprinting of conductive polymers to enable recognition of alpha-synuclein via ultrasensitive electrochemical measurements. The peptide sequences encompassed specific residues where mutations are known to accelerate PD (though the target sequences, in this study, were wild-type.) The different peptide targets were all successfully imprinted, but with differing imprinting effectiveness, probably owing to differences in target carboxylic acids (which can bind to the aniline (AN) m-aminobenzenesulfonic acid (MSAN) MIP polymers.) Composition of the imprinted polymer, (the mole proportions of AN and MSAN), and the concentrations and sequences of imprinted peptide templates were optimized by measuring the electrochemical responses to target peptides. The imprinted electrode can detect alpha-synuclein at fg/mL levels, and was therefore used to measure alpha-synuclein in the culture medium of human brain organoids generated from normal and idiopathic PD patients.

Alpha-Synuclein in the Gastrointestinal Tract as a Potential Biomarker for Early Detection of Parkinson's Disease

The primary pathogenesis associated with Parkinson's disease (PD) occurs in peripheral tissues several years before the onset of typical motor symptoms. Early and reliable diagnosis of PD could provide new treatment options for PD patients and improve their quality of life. At present, however, diagnosis relies mainly on clinical symptoms, and definitive diagnosis is still based on postmortem pathological confirmation of dopaminergic neuronal degeneration. In addition, the similarity of the clinical, cognitive, and neuropathological features of PD with other neurodegenerative diseases calls for new biomarkers, suitable for differential diagnosis. Alpha-synuclein (α-Syn) is a potential PD biomarker, due to its close connection with the pathogenesis of the disease. Here we summarize the currently available information on the possible use of α-Syn as a biomarker of early stages of PD in gastrointestinal (GI) tissues, highlight its potential to distinguish PD and other neurodegenerative diseases, and suggest alternative methods (primarily developed for other tissue analysis) that could improve α-Syn detection procedures or diagnostic methods in general.