While plaques comprised of fibrillar Aβ aggregates are hallmarks of Alzheimer's disease, soluble Aβ oligomers present higher neurotoxicity. Thus, one therapeutic approach is to prevent the formation ...of Aβ oligomers and reduce their associated harmful effects. We have proposed a peptoid mimic of the Aβ hydrophobic KLVFF core as an ideal candidate aggregation inhibitor due to its ability to evade proteolytic degradation via repositioning of the side chain from the α‐carbon to the amide nitrogen. This peptoid, JPT1, utilizes chiral sidechains to achieve a helical structure, while C‐terminal addition of two phenylalanine residues places aromatic groups on two sides of the helix with spacing designed to facilitate interaction with amyloid β‐sheet structure. We have previously shown that JPT1 modulates Aβ fibril formation. Here, we demonstrate that JPT1 also modulates Aβ oligomerization, and we explore the role of the charge on the linker between the KLVFF mimic and the extended aromatic residues. Additionally, we demonstrate that peptoid‐induced changes in Aβ oligomerization correlate with attenuation of oligomer‐induced nuclear factor‐κB activation in SH‐SY5Y human neuroblastoma cells. These findings support the therapeutic potential of peptoids to target early stages of Aβ aggregation and impact the associated Aβ‐induced cellular response.
When SH‐SY5Y human neuroblastoma cells were incubated with 4 μM Aβ1‐42 oligomers (Control), increased nuclear factor‐κB (NF‐κB) activation was visualized. However, when the cells incubated with 4 μM Aβ1‐42 oligomers formed in the presence of peptoids that modulate oligomer formation (JPT1, JPT1_I6K, or JPT1_I6E), significant attenuation of NF‐κB activation was observed.
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Peptoids as an extracellular matrix (ECM) material is gaining importance in in vitro neuronal cell culture studies due to their biocompatibility, self-assembling structure, and stability. ...Mechanotransduction between a neuronal cell and an ECM is mediated by neuronal cell receptors such as integrin and neural cellular adhesion molecule. In this study, using molecular dynamics, we investigate the interaction energies between peptoid and neuronal cell receptors, and also study the effect of peptoid bundle size. We investigate the interaction surface between peptoid bundles and neuronal cell receptors, integrin and neural cellular adhesion molecule, using the solvent accessible surface area method to find the influence of hydrophobic and hydrophilic residues of the peptoid chain. We find the free energy landscape using the umbrella sampling method and then evaluate the potential mean force (PMF) and unbinding force during the dissociation between peptoid bundles and neuronal cell receptors. We find that the peptoid bundles have a higher affinity for the neuronal cell receptors, however increasing the size of peptoid bundles increases the affinity for integrin and neural cell adhesion molecule. PMF data for peptoid and neuronal cell receptor dissociation indicates that binding force increases as the size of the peptoid bundle increases. The higher binding strength during peptoid and neuronal cell receptors are due to the hydrophobic residue cluster area in the binding region. These findings will provide a better insight into using peptoid as an ECM.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
About the Authors: Pamela K. Kreeger * E-mail: kreeger@wisc.edu Affiliation: Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, Wisconsin, United States of America ORCID ...logo https://orcid.org/0000-0001-8193-1007 Amy Brock Affiliation: Department of Biomedical Engineering, University of Texas at Austin, Austin, Texas, United States of America ORCID logo https://orcid.org/0000-0001-8255-9024 Holly C. Gibbs Affiliation: Microscopy and Imaging Center, Texas A&M University, College Station, Texas, United States of America K. Jane Grande-Allen Affiliation: Department of Bioengineering, Rice University, Houston, Texas, United States of America Alice H. Huang Affiliation: Department of Orthopaedics, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America ORCID logo https://orcid.org/0000-0002-5037-6829 Kristyn S. Masters Affiliation: Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, Wisconsin, United States of America ORCID logo https://orcid.org/0000-0001-6911-3116 Padmini Rangamani Affiliation: Department of Mechanical and Aerospace Engineering, University of California San Diego, San Diego, California, United States of America ORCID logo https://orcid.org/0000-0001-5953-4347 Michaela R. Reagan Affiliation: Center for Molecular Medicine, Maine Medical Center Research Institute, Scarborough, Maine, United States of America Shannon L. Servoss Affiliation: Ralph E. Martin Department of Chemical Engineering, University of Arkansas, Fayetteville, Arkansas, United States of America Introduction In the spring of 2020, nearly all academic institutions went to some level of shutdown/quarantine in order to slow the spread of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), the virus that causes Coronavirus Disease 2019 (COVID-19). Consistent with this, some of the authors experienced or observed messaging from department chairs, center leaders, or mentors telling principal investigators (PIs) that the pandemic situation has likely created “extra time” for them to focus on writing grants and developing new ideas. Discussions of these data have focused primarily on the fact that women do a disproportionate amount of house and childcare 5–7, and options used to provide support for this unpaid work have essentially evaporated (e.g., limiting outside workers into the home for cleaning, day cares not accessible to children of nonessential workers, and school and summer camp closures). ...the term “staff” refers to administrative staff, whether in support of the research or teaching missions of the university.
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•Bicelles were functionalized with peptoid.•Bicelle size with and without peptoid was comparable.•Peptoid was incorporated preferentially at the edge.
Cell function is tied to the interactions that ...occur within and across the cell membrane. Therefore, understanding membrane-affiliated interactions is important to many biomedical applications. Advancing the body of knowledge about these interactions will lead to discoveries in biomarker detection and therapeutic targets for disease detection and treatment. Model membrane systems are an effective way to study membrane proteins for such discoveries, allowing for stable protein structure and maintaining native activity. Bicelles, disc-shaped lipid bilayers created by combining long- and short-chain phospholipids, are the model membrane system of focus in this study. Bicelles are accessible from both sides and have a wide size range, which makes them attractive for studying membrane interactions without affecting function. In this work, bicelles were functionalized with peptoids to alter the edge chemistry. Peptoids are suitable for this application because of the large diversity of available side chain chemistries that can be easily incorporated in a sequence-specific manner. The peptoid sequence consists of three functional regions to promote insertion into the edge of bicelles. The insertion sequence at the C-terminus contains two alkyl chains and two hydrophobic, chiral aromatic groups that anchor into the bicelle edge. The facially amphipathic helix contains chiral aromatic groups on one side that interact with the lipid tails and positively charged groups on the other side, which interact with the lipid head groups. Thiol groups are included at the N-terminus to allow for visualization of peptoid location in the bicelle. Bicelle morphology and size were assessed by transmission electron microscopy (TEM) and dynamic light scattering (DLS). Peptoid location in the bicelle was determined by attachment of gold nanoparticles, which confirmed preferential incorporation of the peptoid into the bicelle edge with 82% specificity. Additionally, the peptoid-functionalized bicelles are of similar size and morphology to non-functionalized bicelles. Results from this study show that peptoid-functionalized bicelles are a promising model membrane system with potential applications in biosensors or bioseparations.
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•Polysulfone hollow fiber membranes are modified with a peptoid (NMEG5) using polydopamine.•The addition of peptoid to the fibers increases the hydrophilicity of the fibers by ...74%.•Peptoid-modified fibers have significantly decreased protein fouling with bovine serum albumin, lysozyme, and fibrinogen.•Peptoid-modified fibers show the lowest amount of fibrinogen adsorption compared to other published low fouling membranes.
Biofouling is a persistent problem for membranes exposed to blood or other complex biological fluids, affecting surface structure and hindering performance. In this study, a peptoid with 2-methoxyethyl (NMEG5) side chains was immobilized on polysulfone hollow fiber membranes to prevent protein fouling. The successful attachment of NMEG5 to the polysulfone surface was confirmed by X-ray photoelectron spectroscopy and an increase in hydrophilicity was confirmed by contact angle analysis. The NMEG5-modified surface was found to resist fouling with bovine serum albumin, lysozyme, and adsorbed significantly less fibrinogen as compared with other published low-fouling surfaces. Due to the low fouling nature and increased biocompatibility of the NMEG5 coated membranes, they have potential applicability in numerous biomedical applications including artificial lungs and hemodialysis.
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While the primary pathology of Alzheimer's disease (AD) is defined by brain deposition of amyloid-β (Aβ) plaques and tau neurofibrillary tangles, chronic inflammation has emerged as an important ...factor in AD etiology. Upregulated cell surface expression of the receptor for advanced glycation end-products (RAGE), a key receptor of innate immune response, is reported in AD. In parallel, RAGE ligands, including Aβ aggregates, HMGB1, and S100B, are elevated in AD brain. Activation of RAGE by these ligands triggers release of inflammatory cytokines and upregulates cell surface RAGE. Despite such observation, there are currently no therapeutics that target RAGE for treatment of AD-associated neuroinflammation. Peptoids, a novel class of potential AD therapeutics, display low toxicity, facile blood-brain barrier permeability, and resistance to proteolytic degradation. In the current study, peptoids were designed to mimic Aβ, a ligand that binds the V-domain of RAGE, and curtail RAGE inflammatory activation. We reveal the nanomolar binding capability of peptoids JPT1 and JPT1a to RAGE and demonstrate their ability to attenuate lipopolysaccharide-induced pro-inflammatory cytokine production as well as upregulation of RAGE cell surface expression. These results support RAGE antagonist peptoid-based mimics as a prospective therapeutic strategy to counter neuroinflammation in AD and other neurodegenerative diseases.
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Microneedle patches are a promising source for transdermal diffusion of macromolecules and are designed to painlessly penetrate the skin. In this study, a biodegradable chitosan microneedle patch to ...deliver meloxicam for managing pain in cattle was tested. The potential of reuse of the polymeric solution to fabricate the patches, optimization of fabrication, morphological analysis of the microneedle patch and analysis of preservation of the chemical composition after sterilization were evaluated. In-vitro analysis consisted of studying in-vitro penetration mechanical properties, compression testing analysis of microneedle patch, and in-vitro drug release analysis. In-vivo studies were performed to analyze the dissolution capability of the microneedle patch. Results regarding the physical characteristics, chemical composition, and mechanical properties confirmed that rheological properties of the chitosan solution, present significant differences over time, demonstrating that reusing the solution on the fourth day results in failure patches. Morphological characteristics and chemical composition studies revealed that the process of sterilization (ethylene oxide gas) needed for implanting the patches into the skin did not affect the properties of microneedle patches. In-vitro studies showed that approximately 33.02 ± 3.88% of the meloxicam was released over 7 days. A full penetration of the microneedles into the skin can be obtained by applying approximately 3.2 N. In-vivo studies demonstrated that microneedle patches were capable of swelling and dissolving, exhibiting a dissolution percentage of more than 50% of the original height of microneedle after 7 days. No abnormal tissue, swelling, or inflammation was observed in the implanted area. The results of this work show that chitosan biodegradable microneedle patches may be useful to deliver meloxicam to improve pain management of cattle with positive effects for commercial manufacturing.
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The development of low fouling membranes to minimize protein adsorption has relevance in various biomedical applications. Here, electrically neutral peptoids containing 2-methoxyethyl glycine (NMEG) ...side chains were attached to polysulfone hollow fiber membranes via polydopamine. The number of side chains and grafting density were varied to determine the effect on coating properties and the ability to prevent fouling. NMEG peptoid coatings have high hydrophilicity compared to unmodified polysulfone membranes. The extent of biofouling was evaluated using bovine serum albumin, as well as platelet adhesion. The results suggest that both the number of side chains and grafting density play a role in the surface properties that drive biofouling. Protein adsorption decreased with increasing peptoid grafting density and is lowest above a critical grafting density specific to peptoid chain length. Our findings show that the optimization of grafting density and hydration of the surface are important factors for achieving the desired antifouling performance.
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Antibody microarrays are an emerging technology that promises to be a powerful tool for the detection of disease biomarkers. The current technology for protein microarrays has been derived primarily ...from DNA microarrays and is not fully characterized for use with proteins. For example, there are a myriad of surface chemistries that are commercially available for antibody microarrays, but there are no rigorous studies that compare these different surfaces. Therefore, we have used a sandwich enzyme-linked immunosorbent assay (ELISA) microarray platform to analyze 17 different commercially available slide types. Full standard curves were generated for 23 different assays. We found that this approach provides a rigorous and quantitative system for comparing the different slide types based on spot size and morphology, slide noise, spot background, lower limit of detection, and reproducibility. These studies demonstrate that the properties of the slide surface affect the activity of immobilized antibodies and the quality of data produced. Although many slide types produce useful data, glass slides coated with aldehyde silane, poly-l-lysine, or aminosilane (with or without activation with a crosslinker) consistently produce superior results in the sandwich ELISA microarray analyses we performed.
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Alzheimer’s disease (AD) is characterized by the buildup of insoluble aggregated amyloid-β protein (Aβ) into plaques that accumulate between the neural cells in the brain. AD is the ...sixth leading cause of death in the United States and is the only cause of death among the top ten that cannot currently be treated or cured (Alzheimer’s Association, 2011; Selkoe, 1996). Researchers have focused on developing small molecules and peptides to prevent Aβ aggregation; however, while some compounds appear promising in vitro, the research has not resulted in a viable therapeutic treatment. We previously reported a peptoid-based mimic (JPT1) of the peptide KLVFF (residues 16–20 of Aβ) that modulates Aβ40 aggregation, specifically reducing the total number of fibrillar, β-sheet structured aggregates formed. In this study, we investigate two new variants of JPT1 that probe the importance of aromatic side chain placement (JPT1s) and side chain chirality (JPT1a). Both JPT1s and JPT1a modulate Aβ40 aggregation by reducing total β-sheet aggregates. However, JPT1a also has a pronounced effect on the morphology of fibrillar Aβ40 aggregates. These results suggest that Aβ40 aggregation may follow a different pathway in the presence of peptoids with different secondary structures. A better understanding of the interactions between peptoids and Aβ will allow for improved design of AD treatments.
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