Insight into Amyloid Formation Using Congo Red as the Electrochemical Probe

Veloso, Anthony J.; Chan, Tiffiny; Hung, Vinci Wing Sze; Lam, Leayen; Kerman, Kağan

doi:10.1002/elan.201100329

Cited by 10 publications

(6 citation statements)

References 27 publications

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“…26 Congo Red was also grafted to a screen-printed carbon electrode via an electrooxidation process to provide electrochemical sensors of the aggregation of amyloid-β oligomers in relation to the onset of Alzheimer's disease. 27 Herein, we wish to explore the propensity of isolated diazotized dyes to modify MWCNTs spontaneously. We concentrate our task on tuning the surface chemical composition of MWCNTs using diazotized dyes simply in water and at RT.…”

Section: Introductionmentioning

confidence: 99%

“…For example, diazotized Azure A was (electro)grafted to sp 2 carbon nanomaterials for gas sensing and electrocatalytic purposes, , whereas Neutral Red diazonium salt was generated and attached to gold electrodes through the GraftFast process for making optodes for the measurement of pH . Congo Red was also grafted to a screen-printed carbon electrode via an electrooxidation process to provide electrochemical sensors of the aggregation of amyloid-β oligomers in relation to the onset of Alzheimer’s disease …”

Section: Introductionmentioning

confidence: 99%

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Efficient Covalent Modification of Multiwalled Carbon Nanotubes with Diazotized Dyes in Water at Room Temperature

et al. 2017

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Tetrafluoroborate salts of diazotized Azure A (AA-N), Neutral Red (NR-N) and Congo Red (CR-N) dyes were prepared and reacted with multiwalled carbon nanotubes (MWCNTs) at room temperature, in water without any reducing agent. The as-modified MWCNTs were examined by IRATR, Raman spectroscopy, XPS, TGA, TEM, and cyclic voltammetry. The diazonium band located at ∼2350 cm in the diazotized dye IR spectra vanished after attachment to the nanotubes whereas the Raman D/G peak ratio slightly increased after dye covalent attachment at a high initial diazonium/CNT mass ratio. XPS measurements show the loss of F 1s from the BF anion together with a clear change in the high-resolution C 1s region from the modified nanotubes. Thermogravimetric analyses proved substantial mass loadings of the organic grafts leveling off at 40.5, 34.3, and 50.7 wt % for AA, NR, and CR, respectively. High-resolution TEM pictures confirmed the presence of 1.5-7-nm-thick continuous amorphous layers on the nanotubes assigned to the aryl layers from the dyes. Cyclic voltammetry studies in acetonitrile (ACN) confirmed the grafting of the dyes; the latter retain their electrochemical behavior in the grafted state. The experimental results correlate remarkably well with quantum chemical calculations that indicate high binding energies between the dyes and the CNTs accounting for true covalent bonding (140-185 kJ/mol with the CNT-aryl distance <1.6 nm), though attachment by π stacking also contributes to obtaining stable hybrids. Finally, the pH-responsive character of the robust hybrids was demonstrated by a higher degree of protonation of Neutral Red-grafted CNTs at pH 2 compared to that of the neutral aqueous medium. This work demonstrates that diazotized dyes can be employed for the surface modification of MWCNTs in a very simple and efficient manner in water and at room temperature. The hybrids could be employed for many purposes such as optically pH-responsive materials, biosensors, and optothermal composite actuators to name a few.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Efficient Covalent Modification of Multiwalled Carbon Nanotubes with Diazotized Dyes in Water at Room Temperature

et al. 2017

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“…Redox‐active β‐sheet‐intercalating agents have been used to monitor the kinetics of fibril formation 35–37. The structural changes associated with the β‐sheet formation and aggregation result in quantifiable changes in the electrochemical signal of the intercalated compounds.…”

Section: Recent Developments Of Electrochemical Biosensors For Neurmentioning

confidence: 99%

Electroanalytical Sensors and Methods for Assays and Studies of Neurological Biomarkers

et al. 2014

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Diverse methods have been developed to reveal biochemical changes in neurological disorders and to detect biomarkers present in clinical samples. Electrochemical biosensors are attractive because of their low costs, high sensitivity, and easiness for miniaturization. They have the potential for both point‐of‐care and in vivo monitoring. With clever surface modification and effective immobilization of capture ligands, selective detection of neurological biomarkers can be achieved. This review covers select applications of electroanalytical methods/sensors for proteins, peptides, small molecules, metal ions, and neurotransmitters. Designs of various sensors and devices are reviewed and issues to be addressed for clinically viable sensors are discussed.

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“…Kiessling and co-workers, by immobilizing Ab(1À42) onto an sensor chip, used surface plasmon resonance to screen the various Ab segments for b-sheet breaking peptides [29]. Recently, electrochemical meth-ods have found applications in the studies of Ab aggregation and the dynamic interactions between Ab and a compound of interest [30][31][32][33]. Vestergaard et al were the first to investigate in real time aggregation of Ab peptides by following the variation of the oxidation currents of the tyrosine residue at position 10 (Tyr-10) during the Ab aggregation/fibrillation process [34].…”

Section: Introductionmentioning

confidence: 99%

A Ferrocene‐Tagged Amyloid‐β Fragment for Rapid Screening of Aggregation Inhibitors from Natural Compounds by HPLC‐Electrochemical Detection

et al. 2013

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Aggregates of amyloid beta (Ab) peptides are believed to be responsible for the neuropathology of Alzheimers disease. In this work, ferrocene (Fc) is attached to the aggregating core of the Ab peptides, KLVFFAE. Inhibition of Fc-KLVFFAE aggregation by curcumin, a natural compound, was monitored by HPLC-electrochemical detection (HPLC-EC). The Fc oxidation current is dependent on the incubation condition and curcumin can retain Fc-KLVFFAE in its monomeric form. We demonstrate that tagging Fc to KLVFFAE affords a cost-effective and electroactive mimicry of Ab(1À42) and HPLC-EC is suitable for sensitive, reproducible, and facile screening of drugs for inhibiting the aggregation of Ab peptides.

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Insight into Amyloid Formation Using Congo Red as the Electrochemical Probe

Cited by 10 publications

References 27 publications

Efficient Covalent Modification of Multiwalled Carbon Nanotubes with Diazotized Dyes in Water at Room Temperature

Efficient Covalent Modification of Multiwalled Carbon Nanotubes with Diazotized Dyes in Water at Room Temperature

Electroanalytical Sensors and Methods for Assays and Studies of Neurological Biomarkers

A Ferrocene‐Tagged Amyloid‐β Fragment for Rapid Screening of Aggregation Inhibitors from Natural Compounds by HPLC‐Electrochemical Detection

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