Congo Red‐Derived Carbon Dots: Simultaneously as Fluorescence Probe for Protein Aggregates, Inhibitor for Protein Aggregation, and Scavenger of Free Radicals

Abstract

β-sheet-rich protein aggregates. [2] Protein aggregates deposit in the specific organ or tissue is possibly the significant hallmark of some protein aggregation diseases. [3] For example, the Lewy bodies contain abundant α-synuclein aggregates in the brain of PD patients, [3] and the extracellular senile plaques comprise both of Aβ 1-40 (Aβ 40 ) and Aβ 1-42 (Aβ 42 ) aggregates in the brain of AD patients. [3,4] Specifically, for the AD-associated proteins, Aβ 42 is a more prevalent amyloidogenic protein in the senile plaques, exhibiting faster aggregation rate in vitro and higher neurotoxicity in vivo than Aβ 40 , [4][5][6][7] which is a widely-accepted model aggregative protein in the AD study. [8] The formed protein aggregates, especially the soluble oligomers and protofibrils, could pose high cytotoxicity, causing the damage of cell membrane, dysfunction of organelles (such as mitochondrion and golgi apparatus) as well as cellular oxidative stress with elevated free radical level. [9][10][11][12] Therefore, detection of protein aggregates, inhibition of protein aggregation, and scavenging of free radical would be of great significance for the diagnosis and treatment of the protein aggregation diseases. [13,14] However, it is still challenging to achieve the dual purposes of simultaneous detection and treatment in one method. [15,16] Fluorescence imaging method with the characteristics of being low invasive and real time was widely developed for diagnosis. [13,17] As one of high-profile carbon-based nanomaterials, carbon dots (CDs), with the merits of excellent fluorescence property, good biocompatibility, low cytotoxicity, easy preparation, and low cost, [18,19] were introduced for fluorescence imaging of protein aggregates. [20][21][22][23] However, the fluorescence signals of some CDs were in the blue or green emission range, which were easily interfered by the autofluorescence of biological samples. [24] In contrast, red fluorescence response possessing good anti-interference ability was more preferable. [24] Besides, owing to the size effects and plentiful surface functional groups, CDs aroused researchers' interests in their potential inhibition effects on protein aggregation, which could be a strategy to delay or reverse the diseases. [16] Previously, Gao et al. proposed nitrogen-doped carbonized polymer dots, whichThe pathological aggregation of some proteins is claimed to be highly related to several human diseases, such as β-amyloid 1-42 (Aβ 42 ) to Alzheimer's disease (AD), islet amyloid polypeptide, and insulin to type 2 diabetes mellitus. Therefore, it is in desperate need to develop effective methods for detection of protein aggregates and inhibition of abnormal aggregation. Herein, to construct all-in-one probe with both diagnosis and treatment potentials for protein aggregation diseases, Congo red (CR), a classical staining reagent with red fluorescence signal output for protein aggregates, is deliberately adopted to react with three different reductive carbon sources and ammonium persulfate to ...

Novel photocatalytic carbon dots: efficiently inhibiting amyloid aggregation and quickly disaggregating amyloid aggregates

“…The carbon nanodots with large, conjugated domains can interact with proteins through π–π stacking and hydrophobic interactions, exerting certain inhibitory and disaggregation effects on proteins. 44,54,55 CNDs show concentration-dependent inhibition of lysozyme aggregation without irradiation (Fig. S4a†).…”

Carbon dots from alcohol molecules: principles and the reaction mechanism

“…2(a) and (b)) reveal the characteristic absorption peaks for CDs, which are assigned to O–H (3435 cm −1 ), C–H (2970 cm −1 ), CO (1627 cm −1 ), O–CO (1700 cm −1 ), –CH 3 (1425 cm −1 ), and C–O (1079 cm −1 ) stretching vibrations, respectively. 17,26–28 The element content and surface functional groups of CDs can be further proved by X-ray photoelectron spectroscopy (XPS, Fig. 2(c) and (d)).…”

“…S16(a1)†) of CDs show a C 1s band containing four main peaks near 284.8, 285.4, 286.8, and 288.4 eV, attributed to C–C/CC, C–O, CO, and O–CO groups, respectively. 21,28–30 Fig. S16(a2)† shows four fitting peaks for the high-resolution O 1s spectrum: CO (531.4 eV), O–H (532.4 eV), C–O (533.4 eV), and the Na KLL Auger peak appears at approximately 536.4 eV.…”

Visualization of Phototherapy Evolution by Optical Imaging

“…In addition to caspase-3, an abnormal increase in intracellular viscosity is also a considerable physiological feature of cell apoptosis [ 97 ]. Viscosity in cells is related to many cellular processes, such as protein aggregation, signal transduction, and cell apoptosis [ 98 ].…”