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(a) Atomic force microscopy (AFM) images of amylin (10 μmol·L⁻¹) co-incubated without (black border) or with 20 mg·L⁻¹ L(D)-NIBC-AuNPs (red border: L-NIBC-AuNPs, blue border: D-NIBC-AuNPs) in PBS at 37 °C (Samples collected at 0, 6th, 12th and 24th h of the incubation). (b,c) Time-dependent average sizes (b) and Zeta potential changes (c) of amylin (10 μmol·L⁻¹) co-incubated without (black curve)/with 20 mg·L⁻¹ L(D)-NIBC-AuNPs (red: L-NIBC-AuNPs, blue: D-NIBC-AuNPs) in ultrapure water at 37 °C; dotted curves in c: pure L(D)-NIBC-AuNPs.
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Protein/Peptide amyloidosis is the main cause of several diseases, such as neurodegenerative diseases. It has been widely acknowledged that the unnatural fibrillation of protein/peptides in vivo is significantly affected by the physical and chemical properties of multiscale biological membranes. For example, previous studies have proved that molecu...
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Type 2 diabetes mellitus (T2DM) is a chronic progressive disease characterized by insulin resistance and insufficient insulin secretion to maintain normoglycemia. The majority of T2DM patients bear amyloid deposits mainly composed of islet amyloid polypeptide (IAPP) in their pancreatic islets. These—originally β-cell secretory products—extracellula...
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... Many studies have used different types of molecules with good biocompatibility, such as small organic molecules, amino acids, proteins, peptides, DNAs, and polymers . These ligands not only act as stabilizers but also greatly improve the properties of AuNCs by increasing their PL wavelengths, conferring targeting properties and treating diseases such as cancer (Gao et al., 2019;Li et al., 2019a). In addition, increasing the targeting of AuNCs can greatly improve the contrast and accuracy of the imaging site. ...
Gold nanoclusters (AuNCs) have become a promising material for bioimaging detection due to their tunable photoluminescence, large Stokes shift, low photobleaching and good biocompatibility. Last decade, great efforts have been made to develop AuNCs for enhanced imaging contrast and multimodal imaging. Herein, an updated overview of recent advances in AuNCs was present for visible fluorescence (FL) imaging, near-infrared fluorescence (NIR-FL) imaging, two-photon near-infrared fluorescence (TP-NIR-FL) imaging, computed tomography (CT) imaging, positron emission tomography (PET) imaging, magnetic resonance imaging (MRI), and photoacoustic (PA) imaging. The justification of AuNCs applied in bioimaging mentioned above applications was discussed, the performance location of different AuNCs was highlighted, the performance location of different AuNCs were summarized in the an unified parameter coordinate system of corresponding bioimaging, and the current challenges, research frontiers and prospects of AuNCs in bioimaging were discussed. This review will bring new insights into the future development of AuNCs in bio-diagnostic imaging.
... In the spectra of ALG, a wide absorption peak appeared at 3450 cm −1 , as well as in the spectra of ALG-SH. Meanwhile, a peak related to -SH appeared at 2521 cm −1 [33], which demonstrated that L-cysteine-grafted alginate (ALG-SH) was successfully prepared. Wide absorption bands around 3450 cm −1 , 1641 cm −1 , 1397 cm −1 in the spectra of CNT were attributed to the stretching vibration of -OH, C=O and the bending vibration of -OH from the carboxyl group in CNT [34], respectively. ...
Carbon nanotubes (CNTs) have attracted great interest in biomedical fields. However, the potential toxicity and poor dispersion of CNTs have greatly limited its application. In this work, a mussel-inspired method combined with the "thiol-Michael" click reaction was used to modify the surface of CNT and improve its properties. Firstly, a CNT was treated with dopamine, and then alginate grafted with L-cysteine was anchored onto the surface of CNT via click reaction, which realized the long-time dispersion of CNT in water. Furthermore, the in vitro test also demonstrated that the alginate may improve the biocompatibility of CNT, and thus may broaden the application of CNT in the biomedical field.
... Gold nanoparticles (Au NPs) have received more attention due to their excellent biocompatibility, stability and low cytotoxicity [24][25][26][27][28]. However, the antibacterial activity of Au NPs cannot adequately meet the needs of practical applications compared with Ag NPs and TiO 2 NPs [29][30][31]. ...
d-cysteine (d-cys) has been demonstrated to possess an extraordinary antibacterial activity because of its unique steric configuration. However, inefficient antibacterial properties seriously hinder its wide applications. Here, cysteine-functionalized gold nanoparticles (d-/l-Au NPs) were prepared by loading d-/l-cysteine on the surface of gold nanoparticles for the effective inhibition of Escherichia coli (E. coli) in vitro and in vivo, and the effects on the intestinal microflora in mice were explored during the treatment of E. coli infection in the gut. We found that the antibacterial activity of d-/l-Au NPs was more than 2–3 times higher than pure d-cysteine, l-cysteine and Au NPs. Compared with l-Au NPs, d-Au NPs showed the stronger antibacterial activity, which was related to its unique steric configuration. Chiral Au NPs showed stronger destructive effects on cell membrane compared to other groups, which further leads to the leakage of the cytoplasm and bacterial cell death. The in vivo antibacterial experiment illustrated that d-Au NPs displayed impressive antibacterial activity in the treatment of E. coli-infected mice comparable to kanamycin, whereas they could not affect the balance of intestinal microflora. This work is of great significance in the development of an effective chiral antibacterial agent.
... Recent experiments and calculations show that the aggregation of Aβ(1−42) on Au nanoparticles (AuNP), the most employed nanomaterials for adsorption studies regarding Aβ, seems to accelerate the aggregation of the peptide on the surface, 12,13 and the chirality of this aggregation can be directed by the presence of nanoparticles. 14 Conversely, other studies report that gold nanoparticles on bare 15,16 or modified nanoparticles 17−19 clearly avoid fibrillation, although the aggregation and deposition on the nanoparticle can still take place as for many proteins or peptides that tend to be adsorbed onto metal surfaces. 20,21 Likewise, nanoparticles can be also employed in the detection of Aβ peptides using plasmon-mediated effects. ...
Plasmon-assisted effects were used in this work to study the dynamical behavior of amyloid β peptides (Aβ), in particular Aβ(25-35), on silver nanoparticles. Amyloid peptides derive from the proteolytic cleavage of the glycoprotein named amyloid precursor protein (APP). Aβ(25-35) represents the sequence that concentrates the biological active region of all of the amyloid peptide family, being the shortest fragment of Aβ that retains the toxicity of the full length. The plasmon effects employed in this work were the localized surface plasmon resonance (LSPR), the plasmon hybridization resulting from plasmonic NPs aggregation, and the enhancement of electric field leading to the so-called surface-enhanced Raman scattering (SERS) spectroscopy on nanostructures. While LSPR and plasmon hybridization of nanoparticles are highly sensitive to adsorption and dynamical processes undergone by these peptides on the metal surface, direct nonlabeled SERS spectra provided valuable information regarding the secondary structure of peptides. Specifically, SERS revealed the interaction mechanism of peptides with the metal and the structural rearrangement processes involved in the self-aggregation leading to fibrillation. These effects were also followed at different peptide concentrations. Plasmon resonance and SERS results were obtained with transmission electron microscopy (TEM) images that also corroborated the self-aggregation processes undergone by these peptides leading to the formation of supramolecular aggregates at different concentrations. Nanospheres and protofibrils formed in the first stages of the amyloid assembly were identified by TEM. The physicochemical information provided by this work will be of great importance to design plasmon-based nanoplatforms for simultaneous amyloid detection and structural characterization. Furthermore, these platforms have promising applications in the detection of Alzheimer's disease and its treatment based on the bioaccumulation of these toxic peptides on NPs, where they can be trapped and removed from biological systems, thus reducing their neurotoxicity.
... Furthermore, D-Pen@Se NPs also decreased Zn 2+ -induced intracellular Aβ 40 fibrillation in PC12 cells, while L-Pen@Se NPs did not, suggesting a potential biomedical application of chiral D-Pen@Se NPs (Figure 6). [70]. The authors stated that both enantiomers were able to inhibit amylin fibrillation in a dosedependent way but the inhibition obtained with the L-functionalized NPs was higher than that with the D-functionalized NPs. ...
Chiral molecules, such as amino acids and carbohydrates, are the building blocks of nature. As a consequence, most natural supramolecular structures, such as enzymes and receptors, are able to distinguish among different orientations in space of functional groups, and enantiomers of chiral drugs usually have different pharmacokinetic properties and physiological effects. In this regard, the ability to recognize a single enantiomer from a racemic mixture is of paramount importance. Alternatively, the capacity to synthetize preferentially one enantiomer over another through a catalytic process can eliminate (or at least simplify) the subsequent isolation of only one enantiomer. The advent of nanotechnology has led to noteworthy improvements in many fields, from material science to nanomedicine. Similarly, nanoparticles functionalized with chiral molecules have been exploited in several fields. In this review, we report the recent advances of the use of chiral nanoparticles grouped in four major areas, i.e., enantioselective recognition, asymmetric catalysis, biosensing, and biomedicine.
... To date, nanomaterials and multifunctional nanocomposites possessing certain structural and physicochemical traits are promising candidates for mitigating amyloidosis in vitro and in vivo, indicating the use of nanoparticles as an emerging field against amyloid diseases [16,27]. Gold nanoclusters (AuNCs) (d < 3 nm) have been widely studied in biomedical fields due to their small-size effect and good biocompatibility [28][29][30]. ...
The misfolding of amyloid-β (Aβ) peptides from the natural unfolded state to β-sheet structure is a critical step, leading to abnormal fibrillation and formation of endogenous Aβ plaques in Alzheimer's disease (AD). Previous studies have reported inhibition of Aβ fibrillation or disassembly of exogenous Aβ fibrils in vitro. However, soluble Aβ oligomers have been reported with increased cytotoxicity; this might partly explain why current clinical trials targeting disassembly of Aβ fibrils by anti-Aβ antibodies have failed so far. Here we show that Au23(CR)14 (a new Au nanocluster modified by Cys-Arg (CR) dipeptide) is able to completely dissolve exogenous mature Aβ fibrils into monomers and restore the natural unfolded state of Aβ peptides from misfolded β-sheets. Furthermore, the cytotoxicity of Aβ40 fibrils when dissolved by Au23(CR)14 is fully abolished. More importantly, Au23(CR)14 is able to completely dissolve endogenous Aβ plaques in brain slices from transgenic AD model mice. In addition, Au23(CR)14 has good biocompatibility and infiltration ability across the blood–brain barrier. Taken together, this work presents a promising therapeutics candidate for AD treatment, and manifests the potential of nanotechnological approaches in the development of nanomedicines.
... Indeed, the contributions that are grouped in this Special Issue provide a good idea of the directions in which the field is moving. The contributions range from the synthesis of special nanosystems [1][2][3] to their utilization for sensing [4][5][6][7] and magnetic resonance imaging [8,9], surface recognition [10], and bioapplications [11]. ...
... An increase in the size of nanoparticles to 10 nm or more led to the inhibition of hydrogen chemisorption and prevented its detection. Finally, Gao et al. [11] show a nice example of bio-application of gold nanoparticles. They studied gold nanoparticles (AuNPs, d = 4 ± 1 nm) modified with N-isobutyl-l(d)-cysteine (l(d)-NIBC) enantiomers as a model to illustrate the chiral effect on the amylin fibrillation at the nano-bio interface. ...
When I launched this Special Issue, I wrote: “Gold-based nanosystems are among the most interesting systems in the nanoworld because of their broad spectrum of applications, ranging from analyte detection to nanomedicine and the mimicry of enzymes, just to mention a few examples [...]
Protein misfolding and its aggregation known as amyloid aggregates (Aβ) are one of the major causes of more than 20 diseases such as Parkinson, Alzheimer, type 2 diabetes, etc. The...
Deposit of amyloid peptides in the cells is related to various amyloidosis diseases. A variety of nanomaterials have been developed to resist amyloid deposit. Most of the research on the inhibition of nanomaterials against amyloid aggregation are undertaken in solution, while the membranes that may mediate fibrillar aggregation and affect interaction of inhibitors with amyloid peptides in biotic environment are little taken into account. In this study, we synthesized three kinds of gold nanoclusters modified with cysteine (C@AuNCs), glutathione (GSH@AuNCs) and a peptide derived from the core region of hIAPP fibrillation (C-HL-8P@AuNCs), and investigated their inhibitory activities against hIAPP fibrillation in the absence and presence of lipid vesicles (POPC/POPG 4:1 LUVs) by the experiments of ThT fluorescence kinetics, AFM and CD. We also explored the inhibitions of hIAPP-induced membrane damage and cytotoxicity by peptide@AuNCs using fluorescent dye leakage and cell viability assays. Our study revealed that the inhibitory efficiency of these peptide@AuNCs against hIAPP fibrillation follows C-HL-8P@AuNCs≅GSH@AuNCs>C@AuNCs in lipid-free solution and C-HL-8P@AuNCs≫GSH@AuNCs>C@AuNCs in lipid membrane environment. Compared with the results obtained in lipid-free solution, the inhibitions of hIAPP fibrillation observed in lipid membrane environment were more associated with the inhibitions of hIAPP-induced damages of lipid vesicles and INS-1 cells (C-HL-8P@AuNCs≫GSH@AuNCs>C@AuNCs). An additional hydrophobic interaction with the homologous core region of hIAPP, which is only provided by C-HL-8P@AuNCs and largely suppressed in lipid-free solution, enhanced in the membrane environment and therefore made C-HL-8P@AuNCs much more powerful than GSH@AuNCs and C@AuNCs in the inhibitions of hIAPP fibrillation and cytotoxicity.
