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2.
BMC Endocr Disord ; 19(1): 61, 2019 Jun 13.
Artigo em Inglês | MEDLINE | ID: mdl-31196059

RESUMO

BACKGROUND: Insulin-derived amyloidosis is a skin-related complication of insulin therapy that interferes with insulin therapy. Although toxicities of in vitro-formed insulin amyloid fibrils have been well studied, the toxicity of insulin-derived amyloidosis remains to be clarified. CASE PRESENTATION: A 58-year-old man with type 2 diabetes mellitus underwent a lower limb amputation due to diabetic gangrene. Several antibiotics including minocycline were administered for infection and sepsis. A hard mass at the insulin injection sites in the lower abdomen was discovered by chance four months later. Although no abnormal findings in the surface skin of the mass were observed, necrotic tissue was seen around the mass when a biopsy was performed. Histological and toxicity studies were performed for this patient and four other patients with abdominal masses at insulin injection sites. Histological and immunohistochemical studies showed that the masses had typical characteristics of amyloid deposits in all cases, whereas necrotic findings were seen adjacent to the amyloid deposit only in the case presented. Toxicity studies indicated that the amyloid tissue from the present case had significant cell toxicity compared to the control skin tissue or the amyloid tissues from the other four cases. CONCLUSIONS: This report showed that toxic insulin-derived amyloidosis can occur. In addition, this report suggested that toxic insulin-derived amyloidosis may cause necrosis in the surrounding tissue. Although the toxic amyloid deposit of insulin-derived amyloidosis was found in only one patient, no structural differences between toxic and non-toxic deposits were seen on histological and immunohistochemical studies.

3.
Biomater Sci ; 7(5): 1801-1804, 2019 Apr 23.
Artigo em Inglês | MEDLINE | ID: mdl-30869657

RESUMO

Here we report a novel aspect of molecular chaperone prefoldin (PFD) as a biomaterial in the biocatalytic synthesis of gold nanoparticles (AuNPs) using glycerol dehydrogenase (GLD). We found that PFD could inhibit the aggregation of AuNPs during the biosynthesis, leading to the formation of AuNPs with controlled size distribution.


Assuntos
Ouro/química , Ouro/metabolismo , Nanopartículas Metálicas , Chaperonas Moleculares/metabolismo , Tamanho da Partícula , Biocatálise , Pyrococcus horikoshii/metabolismo , Desidrogenase do Álcool de Açúcar/metabolismo
4.
Anal Sci ; 35(6): 685-690, 2019 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-30827994

RESUMO

Gold nanoparticles (AuNPs) have been commonly used in molecular sensing, in the form of observation of the color change from red to blue of the AuNP solution, caused by target-molecule-induced AuNP aggregation. In this work, the changes in absorbance and scattering spectra caused by AuNP aggregation were studied using thrombin-induced AuNP aggregation as a model. We demonstrated for the first time that scattering spectra is more sensitive to the changes owing to AuNP aggregation than absorbance spectra. Moreover, a digital color analysis of darkfield images using dark field microscopy (DFM) facilitated a simple method for detection of AuNPs aggregation without the use of spectroscopic analysis. Furthermore, we demonstrated that DFM is useful for detecting AuNPs aggregation in a colored solution, in which the color change by AuNPs aggregation is not visible.

5.
Inflamm Regen ; 38: 27, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30459926

RESUMO

Background: Alzheimer's disease is a neurodegenerative disease characterized by the interstitial deposition of amyloid ß (Aß) plaque, which is thought to be related to chronic neuroinflammation. Aß is known to make fibrils via oligomers from monomers. Aß has been reported to activate the NLRP3 inflammasome in infiltrated macrophages. NLRP3, an intracellular pattern recognition receptor, has been reported to recognize numerous pathogens and/or metabolites and form complexes with adopter protein ASC to make the inflammasome, an interleukin (IL)-1ß-processing platform. Although reactive oxygen species from mitochondria have been reported to be involved in the activation of the NLRP3 inflammasome in microglial cells upon the deposition of Aß, whether Aß directly or indirectly activates the NLRP3 inflammasome remains unclear. Methods: We prepared monomers, oligomers, and fibrils of Aß, which promoted the interaction between NLRP3 and each form of Aß and analyzed the interaction between NLRP3 and ASC induced by each form of Aß in a cell-free system with the amplified luminescent proximity homogeneous assay. We also confirmed the physiological relevance in a cell-based assay using human embryonic kidney 293T cells and human peripheral mononuclear cells. Results: Monomers, oligomers, and fibrils of Aß were successfully prepared. Aß oligomers and fibrils interacted with NLRP3. Aß oligomers and fibrils induced the interaction between NLRP3 and ASC. However, Aß monomers did not interact with NLRP3 or induce interaction between NLRP3 and ASC in the cell-free system, and IL-1ß was not secreted according to the cell-based assay. Conclusion: Oligomerized Aß originating from non-toxic Aß monomers directly interacted with NLRP3, leading to the activation of the NLRP3 inflammasome. This may be an attractive target for the treatment of Alzheimer's disease.

6.
Int J Immunopathol Pharmacol ; 32: 2058738418788749, 2018 Jan-Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30014749

RESUMO

Recent findings revealed that type 2 diabetes mellitus (T2D) is a chronic inflammatory disease and an islet amyloid polypeptide (IAPP)/amylin, is deposited within pancreatic islets. IAPP/amylin has been reported to activate NACHT, LRR, and PYD domains-containing protein 3 (NLRP3) inflammasome in infiltrated macrophages. NLRP3, an intracellular pattern recognition receptor, has been shown to recognize pathogens and/or metabolites and complexes with the adopter protein apoptosis-associated speck-like protein containing a caspase-recruitment domain ASC to form a huge complex, called an inflammasome, an interleukin (IL)-1ß-processing platform. Although reactive oxygen species (ROS) were reported to be involved in activation of NLRP3 inflammasome, we were hypothesized that IAPP could directly activate NLRP3 inflammasome, leading to islets ß-cell death. We analyzed expression of the inflammasome components ASC, NLRP3, caspase-1, IL-1ß, IAPP/amylin, and insulin immunohistochemically in Langerhans' islets of autopsy cases. The initial event of NLRP3 inflammasome activation was assessed using a cell-free system consisting of NLRP3 and ASC with the amplified luminescent proximity homogeneous assay. IAPP/amylin deposition in Langerhans' islets was detected and significantly correlated with expressions of IL-1ß and ASC. IAPP/amylin directly interacted with NLRP3 and initiated an interaction between NLRP3 and ASC in a cell-free system. The deposition of IAPP/amylin in ß-cells of Langerhans' islets may act together with the expression level of an inflammasome component, ASC, to regulate IL-1ß processing, and directly lead to the dysfunction of ß-cells. The interaction between IAPP/amylin and NLRP3 could be an attractive drug target to avoid both inflammation and ß-cell death for T2D therapy.

7.
Anal Biochem ; 550: 61-67, 2018 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-29678763

RESUMO

A quenchbody (Q-body) is an antibody-based biosensor that employs fluorescence quenching of the dye(s) attached to the antibody fragment, which are de-quenched upon antigen binding. In this study, we aimed to develop Fab type Q-bodies (UQ-bodies) to aid the diagnosis of Alzheimer's disease (AD). Characteristic senile plaques in AD consist of amyloid-ß peptide (Aß) generated from the amyloid precursor protein. Aß42, one of the major peptide forms, aggregates fast and manifests higher neurotoxicity. Recent studies showed that Aß oligomers, such as Aß-derived diffusible ligand (ADDL), are more toxic than fibrils. Thus, detection of Aß and its oligomers in body fluid might help detect deterioration caused by the disease. To this end, the Fab fragment of the anti-Aß antibody h12A11, which binds preferentially to ADDL, was expressed in Escherichia coli, and labeled with a fluorescent dye at the N terminus of either the heavy chain, or the heavy and light chains, via Cys-containing tag(s) to prepare UQ-bodies. As a result, the double-labeled UQ-bodies detected ADDL with higher sensitivity than that for the Aß peptide. In addition, the UQ-body could be used to image aggregated Aß with a low background, which suggested the potential of UQ-bodies as a fast bioimaging tool.

8.
Biophys Rev ; 10(2): 339-345, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29427249

RESUMO

Prefoldin is a hexameric molecular chaperone found in the cytosol of archaea and eukaryotes. Its hexameric complex is built from two related classes of subunits and has the appearance of a jellyfish: its body consists of a double beta-barrel assembly with six long tentacle-like coiled coils protruding from it. Using the tentacles, prefoldin captures an unfolded protein substrate and transfers it to a group II chaperonin. The prefoldin-group II chaperonin system is thought to be important for the folding of newly synthesized proteins and for their maintenance, or proteostasis, in the cytosol. Based on structural information of archaeal prefoldins, the mechanisms of substrate recognition and prefoldin-chaperonin cooperation have been investigated. In contrast, the role and mechanism of eukaryotic PFDs remain unknown. Recent studies have shown that prefoldin plays an important role in proteostasis and is involved in various diseases. In this paper, we review a series of studies on the molecular mechanisms of archaeal prefoldins and introduce recent findings about eukaryotic prefoldin.

9.
Adv Sci (Weinh) ; 3(10): 1600082, 2016 10.
Artigo em Inglês | MEDLINE | ID: mdl-27840798

RESUMO

Biologically relevant 1,5-diazacyclooctanes derived from polyamines and acrolein, inhibit Aß40 peptide fibrillization and significantly suppress cell cytotoxicity. Formal [4+4] cycloaddition reaction of imines is thus involved in modulating oxidative stress processes associated with neural diseases.

10.
FEBS Lett ; 590(20): 3501-3509, 2016 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-27685427

RESUMO

Biophysical understanding of amorphous protein aggregation can significantly impact diverse area of biotechnology. Here, we report the time dependent salt-induced formation of amorphous aggregation as monitored by fluorescence self-quenching and compare the results with conventional methods for detecting protein aggregation [static light scattering (LS) and dynamic light scattering (DLS)]. As a model protein, we used a bovine pancreatic trypsin inhibitor (BPTI) variant extended by two glycines (C2G) at its C terminus, and three variants where three types of Solubility Controlling Peptide tags (SCP tags) made of five serines (C5S), alanines (C5A) or aspartic acids (C5D) were added to the C terminus of C2G. All variants have a native-like BPTI structure and trypsin inhibitory activity, but different solubilities controlled by the SCP tags. The BPTIs were labeled using NHS-Fluorescein (FAM) conjugated to BPTI's lysines, and we measured the changes in fluorescence intensity occurring upon the addition of NaCl. The fluorescence of all FAM-BPTIs decreased almost immediately, albeit to a different extent, upon addition of salt and became constant after 10 min for 24 h or more. On the other hand, LS and DLS signal changes were dependent on the type of tags. Namely, C2G's LS and DLS signals changed immediately, the signals of C5S and C5A tagged FAM-BPTIs increased slowly from 10 min to 24 h, and those of C5D remained constant. These observations indicated the presence of at least one intermediate step, with increased protein-protein interaction yielding a 'molecular condensation' phase. According to this model, C2G would rapidly turn from 'condensates' to aggregates, whereas C5S and C5A tagged FAM-BPTIs would do so slowly, and the soluble C5D tagged variant would remain in the molecular condensation state.


Assuntos
Aminoácidos/química , Aprotinina/química , Aprotinina/genética , Fluoresceína/química , Cloreto de Sódio/farmacologia , Animais , Bovinos , Difusão Dinâmica da Luz , Fluorescência , Mutação , Conformação Proteica/efeitos dos fármacos , Solubilidade , Coloração e Rotulagem
11.
J Mol Biol ; 428(11): 2405-2417, 2016 06 05.
Artigo em Inglês | MEDLINE | ID: mdl-27079363

RESUMO

Prefoldin is a molecular chaperone that captures an unfolded protein substrate and transfers it to a group II chaperonin. Previous studies have shown that the interaction sites for prefoldin are located in the helical protrusions of group II chaperonins. However, it does not exclude the possibility of the existence of other interaction sites. In this study, we constructed C-terminal truncation mutants of a group II chaperonin and examined the effects of these mutations on the chaperone's function and interaction with prefoldin. Whereas the mutants with up to 6 aa truncation from the C-terminus retained more than 90% chaperone activities for protecting citrate synthase from thermal aggregation and refolding of green fluorescent protein and isopropylmalate dehydrogenase, the truncation mutants showed decreased affinities for prefoldin. Consequently, the truncation mutants showed reduced transfer efficiency of the denatured substrate protein from prefoldin and subsequent chaperonin-dependent refolding. The results clearly show that the C-terminal region of group II chaperonins contributes to their interactions with prefoldin, the transfer of the substrate protein from prefoldin and its refolding.


Assuntos
Chaperoninas do Grupo II/metabolismo , Chaperonas Moleculares/metabolismo , Citrato (si)-Sintase/metabolismo , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Chaperoninas do Grupo II/genética , Chaperonas Moleculares/genética , Mutação/genética , Agregados Proteicos/genética , Ligação Proteica/genética , Desnaturação Proteica , Dobramento de Proteína
12.
Anal Sci ; 32(3): 307-11, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-26960610

RESUMO

Dark field microscopy (DFM) was employed to detect amyloid ß (Aß) fibrils-induced gold nanoparticle (AuNP) aggregation at the single-particle level, with a detection limit of 40 pM fibrils. The sensitivity of this method is higher than that of the current fibril-specific detection method using probe dye, such as thioflavin T, for which sub-µM level of fibrils are necessary. This study further proved the potential application of DFM in the analytical methods based on AuNP aggregation.


Assuntos
Peptídeos beta-Amiloides/análise , Anticorpos Imobilizados/química , Anticorpos Monoclonais/química , Técnicas de Química Analítica , Ouro/química , Nanopartículas Metálicas/química , Fragmentos de Peptídeos/análise , Peptídeos beta-Amiloides/imunologia , Anticorpos Imobilizados/imunologia , Anticorpos Monoclonais/imunologia , Técnicas de Química Analítica/instrumentação , Técnicas de Química Analítica/métodos , Microscopia , Fragmentos de Peptídeos/imunologia , Sensibilidade e Especificidade
13.
Surg Endosc ; 30(9): 4153-9, 2016 09.
Artigo em Inglês | MEDLINE | ID: mdl-26659227

RESUMO

BACKGROUND: Localization of colorectal tumors during laparoscopic surgery is generally performed by tattooing into the submucosal layer of the colon. However, faint and diffuse tattoos may lead to difficulties in recognizing cancer sites, resulting in inappropriate resection of the colon. We previously demonstrated that yttrium oxide nanoparticles doped with the rare earth ions (ytterbium and erbium) (YNP) showed strong near-infrared (NIR) emission under NIR excitation (1550 nm emission with 980 nm excitation). NIR light can penetrate deep tissues. In this study, we developed an NIR laparoscopy imaging system and demonstrated its use for accurate resection of the colon in swine. METHODS: The NIR laparoscopy system consisted of an NIR laparoscope, NIR excitation laser diode, and an NIR camera. Endo-clips coated with YNP (NIR clip), silicon rubber including YNP (NIR silicon mass), and YNP solution (NIR ink) were prepared as test NIR markers. We used a swine model to detect an assumed colon cancer site using NIR laparoscopy, followed by laparoscopic resection. The NIR markers were fixed at an assumed cancer site within the colon by endoscopy. An NIR laparoscope was then introduced into the abdominal cavity through a laparoscopy port. RESULTS: NIR emission from the markers in the swine colon was successfully recognized using the NIR laparoscopy imaging system. The position of the markers in the colon could be identified. Accurate resection of the colon was performed successfully by laparoscopic surgery under NIR fluorescence guidance. The presence of the NIR markers within the extirpated colon was confirmed, indicating resection of the appropriate site. CONCLUSIONS: NIR laparoscopic surgery is useful for colorectal cancer site recognition and accurate resection using laparoscopic surgery.


Assuntos
Neoplasias do Colo/cirurgia , Érbio , Laparoscopia/métodos , Tatuagem/métodos , Itérbio , Ítrio , Animais , Neoplasias do Colo/diagnóstico por imagem , Neoplasias Colorretais/diagnóstico por imagem , Neoplasias Colorretais/cirurgia , Fluorescência , Laparoscópios , Espectroscopia de Luz Próxima ao Infravermelho , Instrumentos Cirúrgicos , Suínos
14.
Biomater Sci ; 3(1): 59-64, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26214189

RESUMO

The use of near-infrared (NIR) light over 1000 nm (OTN-NIR or second NIR) is advantageous for bioimaging because it enables deep tissue penetration due to low scattering and autofluorescence. In this report, we describe the application of rare earth ion-doped ceramic nanoparticles to cancer-targeted NIR imaging using erbium and ytterbium ion-doped yttrium oxide nanoparticles (YNP) functionalized with streptavidin via bi-functional PEG (SA-YNP). YNP has NIR emission at 1550 nm, with NIR excitation at 980 nm (NIR-NIR imaging). Cancer-specific NIR-NIR imaging was demonstrated using SA-YNP and biotinylated antibodies on cancer cells and human colon cancer tissues. NIR-NIR imaging through porcine meat of 1 cm thickness was also demonstrated, supporting the possible application of deep tissue NIR-NIR bioimaging using YNP as a probe. Our results suggest that non-invasive imaging using YNP has great potential for general application in cancer imaging in living subjects.


Assuntos
Cerâmica/química , Neoplasias do Colo/terapia , Érbio/química , Nanopartículas Metálicas/química , Metais Terras Raras/química , Espectroscopia de Luz Próxima ao Infravermelho/métodos , Estreptavidina/química , Ítrio/química , Animais , Linhagem Celular Tumoral , Neoplasias do Colo/química , Humanos , Nanopartículas Metálicas/administração & dosagem , Metais Terras Raras/administração & dosagem , Suínos
15.
FEBS Open Bio ; 5: 124-31, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25737838

RESUMO

The NADH oxidase-peroxiredoxin (Prx) system of Amphibacillus xylanus reduces hydroperoxides with the highest turnover rate among the known hydroperoxide-scavenging enzymes. The high electron transfer rate suggests that there exists close interaction between NADH oxidase and Prx. Variant enzyme experiments indicated that the electrons from ß-NADH passed through the secondary disulfide, Cys128-Cys131, of NADH oxidase to finally reduce Prx. We previously reported that ionic strength is essential for a system to reduce hydroperoxides. In this study, we analyzed the effects of ammonium sulfate (AS) on the interaction between NADH oxidase and Prx by surface plasmon resonance analysis. The interaction between NADH oxidase and Prx was observed in the presence of AS. Dynamic light scattering assays were conducted while altering the concentration of AS and the ratio of NADH oxidase to Prx in the solutions. The results revealed that the two proteins formed a large oligomeric assembly, the size of which depended on the ionic strength of AS. The molecular mass of the assembly converged at approximately 300 kDa above 240 mM AS. The observed reduction rate of hydrogen peroxide also converged at the same concentration of AS, indicating that a complex formation is required for activation of the enzyme system. That the complex generation is dependent on ionic strength was confirmed by ultracentrifugal analysis, which resulted in a signal peak derived from a complex of NADH oxidase and Prx (300 mM AS, NADH oxidase: Prx = 1:10). The complex formation under this condition was also confirmed structurally by small-angle X-ray scattering.

16.
Biotechnol Prog ; 30(2): 470-8, 2014 Mar-Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24399764

RESUMO

In this article, we discuss the effects of amino acids on amyloid aggregation of lysozyme. l-cysteine (Cys) dramatically inhibited fibrillation of lysozyme, whereas other amino acids (including l-arginine) did not. In the presence of Cys, the aggregation pathway of lysozyme shifted from fibrillation to the formation of the small worm-like aggregates with unfolding. The interaction between Cys and lysozyme was observed to be non-covalent, suggesting that the thiophilic interaction between the thiol group on the side chain of Cys and the core sequence of lysozyme significantly contributes to the inhibition of amyloid aggregation. These findings provide a new basis for the design of a biocompatible additive to prevent amyloid fibrillation.


Assuntos
Amiloide , Cisteína/química , Muramidase , Agregados Proteicos/efeitos dos fármacos , Aminoácidos/química , Amiloide/química , Amiloide/efeitos dos fármacos , Amiloide/metabolismo , Animais , Galinhas , Cisteína/farmacologia , Muramidase/química , Muramidase/efeitos dos fármacos , Muramidase/metabolismo , Compostos de Sulfidrila/química , Compostos de Sulfidrila/metabolismo
17.
Phys Chem Chem Phys ; 16(8): 3566-72, 2014 Feb 28.
Artigo em Inglês | MEDLINE | ID: mdl-24413447

RESUMO

Inhibitors of amyloid fibril formation have been at the centre of intense research efforts for the prevention of amyloidosis. Here, we hypothesise that a specific non-covalent interaction, the thiophilic interaction between the side chain of an aromatic residue in a polypeptide and a sulphur atom of the compound, effectively inhibits amyloid fibril formation. Fluorescence spectroscopy and transmission electron microscopy revealed that sulphur compounds, particularly Cys, inhibit the fibrillisation of amyloid-ß 1-40 (Aß40) and 1-42 (Aß42). Interestingly, aggregates of Aß40 and Aß42 induced by Cys were less cytotoxic than those induced by catechin, which is the most typical inhibitor of amyloid fibril formation. Because the essential amino acid, Cys, is an abundant molecule in the blood and cytosol, our data provide a new basis for the prevention of amyloid-related diseases and the elucidation of the mechanism of these diseases.


Assuntos
Peptídeos beta-Amiloides/química , Cisteína/química , Fragmentos de Peptídeos/química , Enxofre/química , Peptídeos beta-Amiloides/metabolismo , Peptídeos beta-Amiloides/toxicidade , Animais , Catequina/química , Sobrevivência Celular/efeitos dos fármacos , Cisteína/metabolismo , Células PC12 , Fragmentos de Peptídeos/metabolismo , Fragmentos de Peptídeos/toxicidade , Ligação Proteica , Ratos
18.
PLoS One ; 8(11): e80262, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-24244667

RESUMO

Amyloid beta (Aß) peptides produced by APP cleavage are central to the pathology of Alzheimer's disease. Despite widespread interest in this issue, the relationship between the auto-assembly and toxicity of these peptides remains controversial. One intriguing feature stems from their capacity to form anti-parallel ß-sheet oligomeric intermediates that can be converted into a parallel topology to allow the formation of protofibrillar and fibrillar Aß. Here, we present a novel approach to determining the molecular aspects of Aß assembly that is responsible for its in vivo toxicity. We selected Aß mutants with varying intracellular toxicities. In vitro, only toxic Aß (including wild-type Aß42) formed urea-resistant oligomers. These oligomers were able to assemble into fibrils that are rich in anti-parallel ß-sheet structures. Our results support the existence of a new pathway that depends on the folding capacity of Aß .


Assuntos
Peptídeos beta-Amiloides/metabolismo , Doença de Alzheimer/genética , Doença de Alzheimer/metabolismo , Peptídeos beta-Amiloides/genética , Animais , Dicroísmo Circular , Microscopia Eletrônica de Transmissão , Células PC12 , Ratos
19.
Langmuir ; 29(46): 14117-23, 2013 Nov 19.
Artigo em Inglês | MEDLINE | ID: mdl-24151962

RESUMO

Nanomaterials are increasingly suggested for the selective adsorption and extraction of complex compounds in biomedicine. Binding of the latter requires specific surface modifications of the nanostructures. However, even complicated macromolecules such as proteins can afford affinities toward basic surface characteristics such as hydrophobicity, topology, and electrostatic charge. In this study, we address these more basic physical interactions. In a model system, the interaction of bovine serum albumin and amyloid ß 42 fibrillar aggregates with carbon-coated cobalt nanoparticles, functionalized with various polymers differing in character, was studied. The possibility of rapid magnetic separation upon binding to the surface represents a valuable tool for studying surface interactions and selectivities. We find that the surface interaction of Aß 42 fibrillar aggregates is mostly hydrophobic in nature. Because bovine serum albumin (BSA) is conformationally adaptive, it is known to bind surfaces with widely differing properties (charge, topology, and hydrophobicity). However, the rate of tight binding (no desorption upon washing) can vary largely depending on the extent of necessary conformational changes for a specific surface. We found that BSA can only bind slowly to polyethylenimine-coated nanomagnets. Under competitive conditions (high excess BSA compared to that for ß 42 fibrillar aggregates), this effect is beneficial for targeting the fibrillar species. These findings highlight the possibility of selective extractions from complex media when advantageous basic physical surface properties are chosen.


Assuntos
Peptídeos beta-Amiloides/química , Cobalto/química , Nanoestruturas/química , Fragmentos de Peptídeos/química , Soroalbumina Bovina/química , Animais , Ligação Competitiva , Carbono/química , Bovinos , Polietilenoimina/química , Ligação Proteica , Multimerização Proteica , Estrutura Secundária de Proteína , Propriedades de Superfície
20.
Chem Commun (Camb) ; 49(68): 7531-3, 2013 Sep 04.
Artigo em Inglês | MEDLINE | ID: mdl-23863889

RESUMO

Dark field imaging was employed to visualize and quantify complementary DNA-induced gold nanoparticle aggregation at the single-particle level, with a detection limit of 100 fM DNA, which allows the highly sensitive detection of single nucleotide polymorphisms (SNPs). Results suggested that the aggregation process is consistent with the cluster-cluster model.


Assuntos
DNA/análise , Ouro/química , Nanopartículas Metálicas/química , Microscopia , Tamanho da Partícula , Polimorfismo de Nucleotídeo Único , Propriedades de Superfície
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