Detection and assessment of alpha-synuclein in Parkinson disease

Advances in biosensors for diagnosis of Alzheimer's and Parkinson's diseases

Early diagnosis by detecting ultralow concentrations of disease biomarkers is critical for timely treatment of the two most common neurodegenerative diseases, Alzheimer's and Parkinson's diseases. Innovative biosensors technologies can provide accurate, faster, and cheaper diagnostic pathways. In this review, the most recent electrochemical and optical sensing and biosensing platforms for diagnosing these diseases are critically selected and reviewed. Diagnostic targets (generally biomarkers) related to each disease and novel technologies, such as nanomaterials and biomolecular techniques to optimize the detection process and enhance signals, are discussed. In particular, multiplex detection and detection of multiple analytes by a (bio) sensing platform, to improve clinical sensitivity and selectivity are considered. This review is intended to open new approaches in the field and advance future research by identifying those strategies that optimize real-world performance and minimize present shortcomings.

Metallic nanomaterials in Parkinson's disease: a transformative approach for early detection and targeted therapy

Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by substantial loss of dopaminergic neurons in the substantia nigra, leading to both motor and non-motor symptoms that significantly impact quality of life. The prevalence of PD is expected to increase with the aging population, affecting millions globally. Current detection techniques, including clinical assays and neuroimaging, lack the sensitivity and specificity to sense PD in its earliest stages. Despite extensive research, there is no cure for PD, and available treatments primarily focus on symptomatic relief rather than halting disease progression. Conventional treatments, such as levodopa and dopamine agonists, provide limited and often temporary relief, with long-term use associated with significant side effects and diminished efficacy. Nanotechnology, particularly the use of metallic-based nanomaterials (MNMs), offers a promising approach to overcome these limitations. MNMs, due to their unique physicochemical properties, can be engineered to target specific cellular and molecular mechanisms involved in PD. These MNMs can improve drug delivery, enhance imaging and biosensing techniques, and provide neuroprotective effects. For example, gold and silver nanoparticles have shown potential in crossing the blood-brain barrier, providing real-time imaging for early diagnosis and delivering therapeutic agents directly to the affected neurons. This review aims to reveal the current advancements in the use of MNMs for the detection and treatment of PD. It will provide a comprehensive overview of the limitations of conventional detection techniques and therapies, followed by a detailed discussion on how nanotechnology can address these challenges. The review will also highlight recent preclinical research and examine the potential toxicity of MNMs. By emphasizing the potential of MNMs, this review article aims to underscore the transformative impact of nanotechnology in revolutionizing the detection and treatment of PD.

Plasma alpha-synuclein predicts cognitive impairment in Parkinson's disease: a systematic review and meta-analysis

BACKGROUND

Alpha-synuclein (ɑ-syn) plays a key role in Parkinson's disease (PD) pathogenesis, but existing studies have found mixed results regarding the associations between plasma ɑ-syn and the development of cognitive impairment. We aim to clarify the potentially important relationship between ɑ-syn level in plasma and development of cognitive impairment in PD through systematic review and meta-analysis.

METHODS

A systematic search was conducted in the PubMed, Embase and Web of Science databases for studies reporting plasma ɑ-syn concentrations and cognitive impairment in PD. Effect directions were plotted to investigate methodological factors, and a meta-analysis was performed comparing PD patients with dementia (PDD) to PD patients with normal cognition (PDNC).

RESULTS

Twenty-five studies were identified for the systematic review, involving 1,888 PD patients. Studies using the clinical diagnostic Movement Disorder Society (MDS) criteria for PD with mild cognitive impairment and PDD found consistently positive associations with plasma ɑ-syn level. This was further supported by a meta-analysis which found a significant standardised mean difference (g = 1.770, 95% CI: 0.749-2.790, p < 0.001) between PDD and PDNC patients in 10 studies. Furthermore, studies using emerging immunomagnetic reduction or single-molecule array techniques to quantify ɑ-syn reported strong positive associations. In contrast, studies using enzyme-linked immunoassay and cognitive screening tests alone found mixed results.

CONCLUSION

There is an overall positive effect between plasma ɑ-syn levels and cognitive impairment in PD. As methodological factors can significantly affect associations, future studies should carefully select ɑ-syn immunoassays and utilise the MDS diagnostic criteria for cognitive impairment in PD.

Differences in Blood and Cerebrospinal Fluid Between Parkinson's Disease and Related Diseases

It is difficult to distinguish Parkinson's disease (PD) in the early stage from those of various disorders including atypical Parkinson's syndrome (APS), vascular parkinsonism (VP), and even essential tremor (ET), because of the overlap of symptoms. Other, more challenging problems will arise when Parkinson's disease develops into Parkinson's disease dementia (PDD) in the middle and late stages. At this time, the differential diagnosis of PDD and DLB becomes thorny. These complicate the diagnostic process for PD, which traditionally heavily relies on symptomatic assessment and treatment response. Recent advances have identified several biomarkers in the blood and cerebrospinal fluid (CSF), including α-synuclein, lysosomal enzymes, fatty acid-binding proteins, and neurofilament light chain, whose concentration differs in PD and the related diseases. However, not all these molecules can effectively discriminate PD from related disorders. This review advocates for a paradigm shift toward biomarker-based diagnosis to effectively distinguish between PD and similar conditions. These biomarkers may reflect the diversity that exist among different diseases and provide an effective way to accurately understand their mechanisms. This review focused on blood and CSF biomarkers of PD that may have differential diagnostic value and the related molecular measurement methods with high diagnostic performance due to emerging technologies.

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.

Use of 3D Printing Techniques to Fabricate Implantable Microelectrodes for Electrochemical Detection of Biomarkers in the Early Diagnosis of Cardiovascular and Neurodegenerative Diseases

This Review provides a comprehensive overview of 3D printing techniques to fabricate implantable microelectrodes for the electrochemical detection of biomarkers in the early diagnosis of cardiovascular and neurodegenerative diseases. Early diagnosis of these diseases is crucial to improving patient outcomes and reducing healthcare systems' burden. Biomarkers serve as measurable indicators of these diseases, and implantable microelectrodes offer a promising tool for their electrochemical detection. Here, we discuss various 3D printing techniques, including stereolithography (SLA), digital light processing (DLP), fused deposition modeling (FDM), selective laser sintering (SLS), and two-photon polymerization (2PP), highlighting their advantages and limitations in microelectrode fabrication. We also explore the materials used in constructing implantable microelectrodes, emphasizing their biocompatibility and biodegradation properties. The principles of electrochemical detection and the types of sensors utilized are examined, with a focus on their applications in detecting biomarkers for cardiovascular and neurodegenerative diseases. Finally, we address the current challenges and future perspectives in the field of 3D-printed implantable microelectrodes, emphasizing their potential for improving early diagnosis and personalized treatment strategies.