Label‐free Electrochemical Sensor for Ex‐vivo Monitoring of Alzheimer's Disease Biomarker

Abstract

1IntroductionAlzheimersd isease (AD) is an eurodegenerative disorder characterizedb ya ggregation of beta-amyloid (Ab) peptidea nd formation of neurofibrillary tangles in the neuronsa sw ell as oxidatived amage of lipids, protein, DNAa nd RNA [1][2][3].A Dc ould be diagnosed by using clinicala nalysis,b ut it could be misdiagnosed with some other neurological diseases.A b peptidew as used as the key marker in the early diagnosis of AD [4] based on several detection methods such as the use of amyloid-reactive dyes [5],b ut this method is disadvantagedb ecause the dye should cross the blood-brain barrier.I na ddition, enzyme-linked immunosorbent assay (ELISA),f luorescence,a nd scanning tunneling microscopy methods have been developedf or detection of Ab [6][7][8].W hile these techniques showed good sensitivity and selectivity,t hey also have some disadvantages such asneeded complicated instrument and semi-quantitativec haracteristics [9].A lso, they need along time for sample preparation and analysis that could results in somes tructuralc hanges of Ab due to the ionic strength, acidity, temperature,a nd other environmental conditions [10,11].I no ur previous work we have reported Ramans pectroscopy as ap owerful technique for monitoring Ab peptide in as hort time without any sample preparation, but the sensing device is also expensive [12].Thus,i ti sc ritically important to developafast sensor that could detect Ab concentrationi ni ts aggregate forming step which would be amore suitable candidate to predict AD.E lectrochemicalt echniques have been widely used in variousb iological fields such as clinicald iagnosis, biomedical research, food quality control and environmental monitoring due to its high sensitivity,s implicity, and rapid response. During the last decade few attempts have been reported to apply differente lectrochemical techniques for monitoring Ab peptides and their aggregated forms by usingv ariousm odified electrodes [13][14][15][16][17][18][19][20][21][22]. However, most of them were electrochemical immunosensor label-based systems for in-vitro detection;t hey also include immobilization of peptide into the electrode surface or the detection of the Ab in solutions such as Fe(CN) 6 3À that could change the peptide structure[ 21, 23] D-galactose (DG) is one of the reducing sugars that could be converted into glucose by galactose-1-phosphate uridyltransferase and galactokinase enzymes [24,25].B ut, at higher levels it will be accumulated in the cells and reacts with the free amines (in proteins and peptides) to form advancedg lycation end products [25] leadingt oo smotic stress and generation of reactiveo xygen species [26].D Gw as used for studying in-vivo AD [27][28][29][30],d ue to its ability to induce oxidative stress in cultured rat fetal brain neurons that may be contributed to the neurode-Abstract:T he beta-amyloid (Ab)p eptide was useda sa n important biomarker for Alzheimersd isease (AD) diagnosis.T he developmento fa na ccurate,s elective, rapid, and highly sensitive technique for detecti...

Rapid and highly sensitive detection of pyocyanin biomarker in different Pseudomonas aeruginosa infections using gold nanoparticles modified sensor

“…In the present work, the preparation of Au NPs decorated ITO electrode was performed via electrochemical deposition of Au nanostructures onto the ITO substrate based on CV technique. The electrochemical deposition process was performed within a potential window from 1.5 V to -1.0 V for 5 cycles to allow a complete reduction of Au 3+ ions into Au 0 [20]. Fig 1 demonstrated a reduction peak at -0.5, -0.13 and 0.1 V, anodic peak at -0.1 and 0.84 V during the first cycle of Au nanoparticles deposition, which is shifted to -0.35 & 0.41 V; in addition to oxidation peaks at 0.061 & 0.84 V during the deposition process in the remaining 4 cycles.…”

“…Fig 1 demonstrated a reduction peak at -0.5, -0.13 and 0.1 V, anodic peak at -0.1 and 0.84 V during the first cycle of Au nanoparticles deposition, which is shifted to -0.35 & 0.41 V; in addition to oxidation peaks at 0.061 & 0.84 V during the deposition process in the remaining 4 cycles. The shifting in the reduction peaks is related to the reduction process of Au 3+ to form metallic Au nanostructures on the ITO electrode surface [20].…”

“…Gold (Au) nanostructures are currently used to modify electrodes of biosensors because of its excellent optical and electrical properties and affinity to bind with biomolecules [20–27]. Moreover, the Au nanostructures decorated indium tin oxide (ITO) substrate was successfully used to detect several multidrug-resistant bacteria [28].…”

Mesoporous silica films as hard templates for electrodeposition of nanostructured gold

“…The potential was scanned between 1.4 and -1.1 V as this potential window results in complete reduction of Au 3+ ions to Au(0). 36 Two reduction peaks at 0.07 V and -0.27 V on bare TiN substrate and at 0.55 V and 0.25 V on bare ITO substrate were observed, indicating two reduction reactions of [AuCl 4 ] -. After a wave peak at 0.33 V, diffusion-limited deposition behaviour was displayed on TiN.…”