Dumbbell Aptamer Sensor Based on Dual Biomarkers for Early Detection of Alzheimer’s Disease

Abstract

Finding a timely, sensitive, and noninvasive detection method has become an urgent need for asymptomatic early diagnosis of Alzheimer’s disease (AD). MicroRNA-193b (miR-193b) and Aβ42 oligomers (AβO42) in neurogenic exosomes were confirmed to reflect pathological changes in the AD early stage. The combination of two biomarkers is promising for the earlier detection of AD. In this study, a detection system based on the principle of the entropy-driven strand displacement reaction (ESDR) was developed, including a dumbbell detection probe (H), an indicator probe (R), and graphene oxide (GO). In the detection system, the two hairpins of H were opened by the interaction of miR-193b (T1) and AβO42 (T2) with the aptamer. Then R hybridized with H and began to displace T, initiating the next round of ESDR to achieve sensitive detection of T. GO specifically adsorbed free R and quenched the fluorescence, further reducing the intensity of the background signal. Both of these points provided the system with a more sensitive analytical performance. The detection limit of miR-193b was 77 pM and the detection limit of AβO42 was 53 pM. This sensor detected the change of “one increase (AβO42) and one decrease (miR-193b)” in the exosome sample. Additionally, results showed that this detection system could distinguish the model of early AD from the non-AD control, which was sufficient for earlier and more sensitive detection of AD. This strategy has strong specificity, high sensitivity, and easy operation, which provides broad prospects for the early diagnosis of AD.

Extracellular vesicles as nanotheranostic platforms for targeted neurological disorder interventions

“…(Bottom right) Reproduced with permission from [ 232 ]. Copyright © 2019, The Author(s), (B) Schematic diagram of the detection process of the dual recognition of miRNA-193b and AβO42, Reproduced with permission from [ 236 ]. Copyright © 2023, American Chemical Society.…”

“…A multiplexed approach, which combines two or more biomarkers, can greatly enhance the specificity and sensitivity of AD diagnostics. Recently, Zhou and colleagues have advanced the field of diagnostics with the development of a highly sensitive and non-invasive fluorescent biosensor for simultaneously detecting two critical biomarkers associated with the early stages of AD [ 236 ], as illustrated in Fig. 3 b.…”

Dumbbell Dual-Hairpin Triggered DNA Nanonet Assembly for Cascade-Amplified Sensing of Exosomal MicroRNA

“…The dumbbell hairpin is a specially designed probe that has been widely applied in liquid biopsy. − Chen et al designed a dumbbell hairpin that can recognize dual miRNAs simultaneously, combined Ag + and Hg 2+ , and used CdTe quantum dots and carbon dots to achieve signal amplification for enzyme-free amplification and instant detection of dual miRNAs in urine . Dong et al developed a dumbbell probe based on entropy-driven strand displacement reaction, capable of specifically identifying the altered fluorescence (FL) signal produced by miR-193b and Aβ42 oligomers, and used graphene oxide to reduce the background signal for more sensitive detection . However, these researchers introduced other methods or materials to amplify the sensing signal, treating the dumbbell hairpin as a simple tool for signal conversion rather than the main role of signal amplification.…”

“… 43 Dong et al developed a dumbbell probe based on entropy-driven strand displacement reaction, capable of specifically identifying the altered fluorescence (FL) signal produced by miR-193b and Aβ42 oligomers, and used graphene oxide to reduce the background signal for more sensitive detection. 44 However, these researchers introduced other methods or materials to amplify the sensing signal, treating the dumbbell hairpin as a simple tool for signal conversion rather than the main role of signal amplification. Therefore, the application of dumbbell hairpins in biosensing is still relatively simple, and there is still a lot of room for play.…”

Nano-Brush Structure for Rapid Label-Free Differentiation of Alzheimer’s Disease Stages and Direct Capture of Neuron-Derived Exosomes from Human Blood Plasma

“…Neurofilament light chain (NFL) levels and neuron-derived exosomes (NDEs) in the central nervous system and human blood plasma/serum are promising biomarkers for early stages of AD. NFL levels have been proposed to predict disease progression in the early presymptomatic stages of familial AD and have also been associated with disease severity and prognosis in frontotemporal dementia. ,, On the other hand, exosomes, nano-sized extracellular vesicles (EVs) (30–150 nm) found in biofluids, carry important biomolecules from their cell of origin. − Exosomes have been extensively studied for their potential in diagnosing and predicting various dementia diseases, including AD, ,,− Parkinson’s disease (PD), and mental disorders. − Specialized synaptic proteins in NDEs ,, and Aβ-NDEs ,, have been applied to predict AD development before clinical symptoms appear. These studies suggest that specific exosomes released by neurons can cross the blood–brain barrier and serve as accessible diagnostic markers for neural dysfunction and diseases.…”