Polyallylamine Binds to Aβ Amyloid and Inhibits Antibody Recognition.

Protein amyloids have attracted attention for their application as functional amyloid materials because of their strong properties, such as high resistance to chemical or biological degradation, despite their medical issues. Amyloids can be used for various applications by modifying the amyloid surface with functional materials, such as proteins and polymers. In this study, we investigated the effect of polyallylamine (PAA), a functional cationic polymer as a candidate for amyloid modification, on the amyloids formed from amyloid β (Aβ) peptide.

Detection of estradiol with a digital immunoassay using an anti-immunocomplex antibody and single-molecule observation of gold nanoparticles.

Gold nanoparticles (AuNPs) have been widely applied to molecular sensors due to their optical properties. We previously reported a molecular detection by observing the scattered light of AuNPs at a single nanoparticle level using dark field microscopy (DFM). Recently, a molecular detection method using digital immunoassay has been reported, taking advantage of the characteristics of DFM.

Correction: Effect of DNA density immobilized on gold nanoparticles on nucleic acid detection.

[This corrects the article DOI: 10.1039/D3RA06528F.].

Effect of DNA density immobilized on gold nanoparticles on nucleic acid detection.

Gold nanoparticles (AuNPs) have been utilized as colorimetric biosensors, where target molecule-induced AuNP aggregation can be recognized by a colour change from red to blue. Particularly, single-stranded DNA (ssDNA)-immobilized AuNPs (ssDNA-AuNPs) have been applied to genetic diagnosis due to their rapid and sequence-specific aggregation properties. However, the effect of the density of immobilized ssDNA have not been investigated yet.

Peroxynitric acid inhibits amyloid β aggregation.

Peroxynitric acid (PNA), a reactive oxygen nitrogen species, has attracted attention in life science because of its unique properties such as high bacteriacidal activity. Since the bactericidal activity of PNA could be related to its reaction with amino acid residues, we speculate that PNA can be used for protein modifications. In this study, PNA was applied to inhibit aggregation of amyloid β1-42 (Aβ42), which is thought to cause Alzheimer's disease (AD).

[Insulin-derived amyloidosis (insulin ball) and skin-related complications of insulin therapy].

Skin-related complications of insulin therapy have long been a problem as a factor interfering with insulin therapy. Among the traditional skin-related complications, lipoatrophy and insulin allergy have decreased markedly with the development of insulin preparations, but lipohypertrophy is still common in insulin-treated patients. Recently, there have been more reports of a skin-related complication called insulin-derived amyloidosis or insulin ball.

Analysis of the enzymatic degradation of lysozyme fibrils using a combination method of non-denaturing gel electrophoresis and double staining with Coomassie Brilliant Blue G-250 and R-250 dyes.

The Amyloid fibrils of proteins are involved in various diseases, such as Alzheimer's disease. To suppress such amyloid fibrils, it is essential to develop methods to elucidate their enzymatic degradation process. Lysozyme in egg white has been well studied as a model protein of amyloid fibrils.

Inflammasome assembly is required for intracellular formation of β2-microglobulin amyloid fibrils, leading to IL-1β secretion.

Introduction: Dialysis-related amyloidosis (DRA) caused by β2-microgloblin (B2M) fibrils is a serious complication for patients with kidney failure on long-term dialysis. Deposition of B2M amyloid fibrils is thought to be due not only to serum extracellular B2M but also to infiltrating inflammatory cells, which may have an important role in B2M amyloid deposition in osteoarticular tissues in patients with DRA. Here, we asked whether B2M amyloid fibrils activate the inflammasome and contribute to formation and deposition of amyloid fibrils in cells.

Differences in interaction lead to the formation of different types of insulin amyloid.

Insulin balls, localized insulin amyloids formed at the site of repeated insulin injections in patients with diabetes, cause poor glycemic control and cytotoxicity. Our previous study has shown that insulin forms two types of amyloids; toxic amyloid formed from the intact insulin ((i)-amyloid) and less-toxic amyloid formed in the presence of the reducing reagent TCEP ((r)-amyloid), suggesting insulin amyloid polymorphism. However, the differences in the formation mechanism and cytotoxicity expression are still unclear.

Molecular detection using aptamer-modified gold nanoparticles with an immobilized DNA brush for the prevention of non-specific aggregation.

Gold nanoparticles (AuNPs) are often used for biosensing. In particular, aptamer-modified AuNPs are often used for colorimetric molecular detection, where target molecule-induced AuNP aggregates can be recognized by a color change from red to blue. However, non-specific aggregation could be induced by various compounds, leading to false-positive results.

Colorimetric detection of thrombin based on signal amplification by transcription-reverse transcription concerted reaction using non-crosslinking aggregation of gold nanoparticles.

Gold nanoparticles (AuNPs) have been used as colorimetric biosensors by utilizing the difference in color between the dispersed (red) and aggregated (blue) states. We previously developed a biosensor that converts sandwich-type thrombin recognition to RNA amplification and color difference of AuNPs. But the sensitivity was insufficient because of the linear signal amplification mechanism.

Recent advances in research on biointerfaces: From cell surfaces to artificial interfaces.

Biointerfaces are regions where biomolecules, cells, and organic materials are exposed to environmental media or come in contact with other biomaterials, cells, and inorganic/organic materials. In this review article, six research topics on biointerfaces are described to show examples of state-of-art research approaches. First, biointerface design of nanoparticles for molecular detection is described.

Inhibition of amyloid formation of amyloid β (1-42), amylin and insulin by 1,5-diazacyclooctanes, a spermine-acrolein conjugate.

Amyloid aggregates of proteins are known to be involved in various diseases such as Alzheimer's disease (AD). It is therefore speculated that the inhibition of amyloid formation can play an important role in the prevention of various diseases involving amyloids. Recently, we have found that acrolein reacts with polyamines, such as spermine, and produces 1,5-diazacyclooctane, such as cyclic spermine (cSPM).

Insulin amyloid fibrils interact directly with the NLRP3, resulting in inflammasome activation and pyroptotic cell death.

Introduction: Nucleotide-binding oligomerization domain-like receptor family, pyrin domain containing 3 (NLRP3), an intracellular pattern recognition receptor, recognizes various pathogen-associated molecular pattern and/or damage-associated molecular pattern molecules to constitute inflammasome that act as an interleukin (IL)-1β processing platform. Injected insulin is reported to induce focal amyloidosis and the formation of subcutaneous lumps called insulin balls, but the formation of subcutaneous lumps and the underlying cytotoxic mechanism has not been elucidated.

Methods: Amyloid formation was evaluated by thioflavin T spectroscopic assay and scanning electron microscopy.

Transcription-Based Amplified Colorimetric Thrombin Sensor Using Non-Crosslinking Aggregation of DNA-Modified Gold Nanoparticles.

Gold nanoparticles (AuNPs) have been employed as colorimetric biosensors due to the color difference between their dispersed (red) and aggregated (blue) states. Although signal amplification reactions triggered by structural changes of the ligands on AuNPs have been widely used to improve measurement sensitivity, the use of ligands is limited. In this study, we designed a AuNP-based signal-amplifying sandwich biosensor, which does not require a conformational change in the ligands.

Degradation of insulin amyloid by antibiotic minocycline and formation of toxic intermediates.

Insulin balls, localized insulin amyloids formed at subcutaneous insulin-injection sites in patients with diabetes, cause poor glycemic control owing to impairments in insulin absorption. Our previous study has shown that some insulin balls are cytotoxic, but others are not, implying amyloid polymorphism. Interestingly, the patient with toxic insulin balls had been treated with antibiotic minocycline, suggesting a possible relationship between toxicity of insulin balls and minocycline.

Protein-Functionalized Gold Nanoparticles for Antibody Detection Using the Darkfield Microscopic Observation of Nanoparticle Aggregation.

Gold nanoparticles (AuNPs) are commonly used in biosensing applications. In this study, AuNPs were synthesized by using reduced bovine serum albumin (rBSA) as the reducing agent. The rBSA conjugated with AuNPs via Au-Sulfur interactions to form rBSA-functionalized AuNPs (rBSA-AuNPs).

Insulin amyloid polymorphs: implications for iatrogenic cytotoxicity.

Amyloid specific fluorescent probes are becoming an important tool for studies of disease progression and conformational polymorphisms in diseases related to protein misfolding and aggregation such as localized and systemic amyloidosis. Herein, it is demonstrated that using the amyloid specific fluorescent probes pFTAA and benzostyryl capped benzothiadiazole BTD21, structural polymorphisms of insulin amyloids are imaged in localized insulin-derived amyloid aggregates formed at subcutaneous insulin-injection sites in patients with diabetes. It is also found that pFTAA and BTD21 could discriminate structural polymorphisms of insulin amyloids, so called fibrils and filaments, formed .

Insulin-derived amyloidosis without a palpable mass at the insulin injection site: A report of two cases.

To date, almost all case reports of insulin-derived amyloidosis described the presence of a subcutaneous mass that was observable on physical examination. This report presents two cases of insulin-derived amyloidosis without palpable masses at insulin injection sites. In both cases, blood glucose concentrations improved, and the insulin dose could be reduced by an average of 45% after changing the insulin injection sites.

Toxicity of insulin-derived amyloidosis: a case report.

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.

Molecular chaperone prefoldin-assisted biosynthesis of gold nanoparticles with improved size distribution and dispersion.

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.

Detection of Gold Nanoparticles Aggregation Using Light Scattering for Molecular Sensing.

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.

Amyloid β directly interacts with NLRP3 to initiate inflammasome activation: identification of an intrinsic NLRP3 ligand in a cell-free system.

Background: Alzheimer's disease is a neurodegenerative disease characterized by the interstitial deposition of amyloid β (Aβ) plaque, which is thought to be related to chronic neuroinflammation. Aβ is known to make fibrils via oligomers from monomers. Aβ has been reported to activate the NLRP3 inflammasome in infiltrated macrophages.