High-Sensitivity and Trace-Amount Specimen Electrochemical Sensors for Exploring the Levels of β-Amyloid in Human Blood and Tears

Abstract

As the occurrence of Alzheimer’s disease (AD) has increased, the detection and treatment of AD have become global social issues. Effective early detection and wide-range screening of AD allow patients to gain early control and delay brain degeneration. For these reasons, we choose electrochemical sensors to complete the detection task. Although bio-electrochemical technology for antibody and antigen sensing is not a new technology, considering the scarcity of tear samples for dementia and since the existing AD detection techniques are highly invasive and expensive for subjects, we have to use the traditional detection techniques for the early screening of Alzheimer’s disease via trace-amount specimens. An AD-related protein in the eye is thought to be an important biomarker for early detection. To carry out detection using tear samples as a test specimens, a tear collection device was developed in this study that extracted 10 μL of tear fluid from a tear Schirmer strip. In this research, we distinguished healthy people in different age groups and detect Aβ in both tear and blood samples. We developed a biosensor, which could detect Aβ in tear specimen from 1 to 100 pg/mL. Also, this biosensor is inexpensive, disposable, and easy to use. In our result, the concentration of Aβ in tears was approximately 10 times more than that in blood. This study demonstrates the feasibility and prospects of future screening for AD-associated biomarkers by a dynamic comparison between blood and tears.

Alzheimer’s Disease Seen through the Eye: Ocular Alterations and Neurodegeneration

“…Even though the volume of tear samples is small, advances in proteomics and lipidomics have allowed for a better understanding of tear components and their involvement in different diseases [ 123 ]. In this regard, biotechnological tools are being developed to optimize the extraction of samples from collection devices (such as Schirmer strips or capillaries) and to improve the detection of markers, such as β-amyloid, in tears (using biosensors) [ 124 ]. Hopefully, these new tools will help to overcome the limitations related to the small volume of tear samples.…”

Non-Invasive Nasal Discharge Fluid and Other Body Fluid Biomarkers in Alzheimer’s Disease

“…Other Aβ peptides, Aβ 38 and Aβ 40 , were also detected in their subsequent study [ 119 ]. Recently, Wang et al developed a biosensor and detected variable Aβ 42 levels in different age groups of healthy participants [ 120 ]. Gijs et al also analyzed T-tau, and its levels were also able to discriminate between AD patients and healthy controls with an AUC of 0.81 [ 118 , 119 ].…”

Ophthalmic Biomarkers for Alzheimer’s Disease: A Review

“…Tear fluid • Changes in the composition of the chemical barrier of tears and proteomics (Gijs et al, 2019;Kalló et al, 2016;Kenny et al, 2019;Wang et al, 2021)…”

“…Total microRNA profusion was found at increased levels in the tear of AD patients, with microRNA-200b-5p as the most promising AD biomarker (Kenny et al, 2019). Wang et al (2021) developed a biosensor that could detect Aβ in tear specimens. They concluded the prospect of future screening for AD by using tear biomarkers.…”