Tartaric acid-based amphiphilic macromolecules with ether linkages exhibit enhanced repression of oxidized low density lipoprotein uptake

The relationship between the chemical structure, physicochemical properties, and mucosal adjuvanticity of sugar-based surfactants

The relationship between the chemical structure, physicochemical properties, and mucosal adjuvanticity of sugar-based surfactants (SBSs) has not been sufficiently elucidated. Thus, in the present study, we systematically analyzed 11 SBSs for mucosal adjuvanticity. Ovalbumin (OVA)-specific antibody titers were measured in mice immunized intranasally with OVA plus SBS. We found that four SBSs (trehalose monododecanoate, sucrose monododecanoate, n-dodecyl-α-d-maltopyranoside, and n-dodecyl-β-d-maltopyranoside) exhibited the most potent adjuvanticity. We identified the following associations between chemical structure and adjuvanticity: 1) OVA-specific antibody titer increased with an increasing number of carbon atoms in the alkyl chain; 2) the adjuvanticity was not affected by the type of sugar or bond between the sugar and alkyl chain; and 3) SBSs with rigid structures exhibited less adjuvanticity. The relationship between physicochemical properties and adjuvanticity was as follows: 1) SBSs exhibited adjuvanticity above the critical micelle concentration and 2) in the SBSs with potent adjuvanticity, the diameter of the SBS-OVA complex was 70-75 nm. Our study indicates evidence for the direct involvement of chemical structure and physicochemical properties in determining adjuvanticity in SBSs.

CD36-Binding Amphiphilic Nanoparticles for Attenuation of Alpha Synuclein-Induced Microglial Activation

Neuroinflammation is one of the hallmarks contributing to Parkinson's Disease (PD) pathology, where microglial activation occurs as one of the earliest events, triggered by extracellular alpha synuclein (aSYN) binding to the CD36 receptor. Here, CD36-binding nanoparticles (NPs) containing synthetic tartaric acid-based amphiphilic polymers (AMs) were rationally designed to inhibit this aSYN-CD36 binding. In silico docking revealed that four AMs with varying alkyl side chain lengths presented differential levels of CD36 binding affinity and that an optimal alkyl chain length would promote the strongest inhibitory activity towards aSYN-CD36 interactions. In vitro competitive binding assays indicated that the inhibitory activity of AM-based NPs plateaued at intermediate side chain lengths of 12- and 18-carbons, supporting the in silico docking predictions. These 12- and 18-carbon length AM NPs also had significantly stronger effects on reducing aSYN internalization and inhibiting the production of the proinflammatory molecules TNF-α and nitric oxide from aSYN-challenged microglia. All four NPs modulated the gene expression of aSYN-challenged microglia, downregulating the expression of the proinflammatory genes TNF, IL-6, and IL-1β, and upregulating the expression of the anti-inflammatory genes TGF-β and Arg1. Overall, this work represents a novel polymeric nanotechnology platform that can be used to modulate aSYN-induced microglial activation in PD.

Characteristics of the pH-regulated aggregation-induced enhanced emission (AIEE) and nanostructure orchestrate via self-assembly of naphthalenediimide–tartaric acid bola-amphiphile: role in cellular uptake

A naphthalene diimide–tartaric acid conjugate was successfully synthesized, and the influence of tartaric acid on the self-assembly of the NDI–TA scaffold was explored.

Nanoparticles for Detection and Treatment of Peripheral Arterial Disease

Peripheral arterial disease (PAD) is defined as a slow, progressive disorder of the lower extremity arterial vessels characterized by chronic narrowing that often results in occlusion and is associated with loss of functional capacity. Although the PAD occurrence rate is increasing in the elderly population, outcomes with current treatment strategies are suboptimal. Hence, there is an urgent need to develop new technologies that overcome limitations of traditional modalities for PAD detection and therapy. In this Review, the application of nanotechnology as a tool that bridges the gap in PAD diagnosis and therapy is in focus. Several materials including synthetic, natural, biodegradable, and biocompatible materials are used to develop nanoparticles for PAD diagnostic and/or therapeutic applications. Moreover, various recent research approaches are being explored to diagnose PAD through multimodality imaging with different nanoplatforms. Further efforts include targeted delivery of various therapeutic agents using nanostructures as carriers to treat PAD. Last, but not least, despite being a fairly new field, researchers are exploring the use of nanotheranostics for PAD detection and therapy.

Pedunculoside, a novel triterpene saponin extracted from Ilex rotunda, ameliorates high-fat diet induced hyperlipidemia in rats

Pedunculoside (PE) is a novel triterpene saponin extracted from the dried barks of Ilex rotunda Thunb. The present study aims to explore lipid-lowering effects of PE on hyperlipidemia rat induced by high-fat diet. The rats were fed with the high-fat diet and subjected to intragastric administration of PE at doses of 30, 15, or 5 mg/kg daily for 7 weeks. The results demonstrated that treatment with PE for 7-week dramatically decreased serum total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) and reduced liver TC in hyperlipidemia rat induced by high-fat diet. Furthermore, the results also showed that PE modulated the expression of enzymes involved in lipid metabolism including peroxisome proliferator-activated receptor α (PPAR-α), sterol regulatory element-binding protein 1 (SREBP-1), fatty acid synthase (FAS) and stearoyl CoA desaturase-1 (SCD-1) mRNA in liver. Besides, PE-treated group decreased weights and diameters of epididymal adipose hyperlipidemia rat. Mechanism study demonstrated that PE regulated PPAR-γ, CCAAT/Enhancer-binding Protein α (C/EBPα)、and SREBP-1 expression as well as inhibited phosphorylation of AMPK in MDI (methylisobutylxanthine, dexamethasone, insulin) induced-3T3L1 cells. Molecular Docking confirmed interaction between PE with proteins involving PPAR-γ, C/EBPα and SREBP-1. In summary, these findings may support that PE is a novel lipid-lowering drug candidate.

Nanotherapeutics Containing Lithocholic Acid-Based Amphiphilic Scorpion-Like Macromolecules Reduce In Vitro Inflammation in Macrophages: Implications for Atherosclerosis

Previously-designed amphiphilic scorpion-like macromolecule (AScM) nanoparticles (NPs) showed elevated potency to counteract oxidized low-density lipoprotein (oxLDL) uptake in atherosclerotic macrophages, but failed to ameliorate oxLDL-induced inflammation. We designed a new class of composite AScMs incorporating lithocholic acid (LCA), a natural agonist for the TGR5 receptor that is known to counteract atherosclerotic inflammation, with two complementary goals: to simultaneously decrease lipid uptake and inhibit pro-inflammatory cytokine secretion by macrophages. LCA was conjugated to AScMs for favorable interaction with TGR5 and was also hydrophobically modified to enable encapsulation in the core of AScM-based NPs. Conjugates were formulated into negatively charged NPs with different core/shell combinations, inspired by the negative charge on oxLDL to enable competitive interaction with scavenger receptors (SRs). NPs with LCA-containing shells exhibited reduced sizes, and all NPs lowered oxLDL uptake to <30% of untreated, human derived macrophages in vitro, while slightly downregulating SR expression. Pro-inflammatory cytokine expression, including IL-1β, IL-8, and IL-10, is known to be modulated by TGR5, and was dependent on NP composition, with LCA-modified cores downregulating inflammation. Our studies indicate that LCA-conjugated AScM NPs offer a unique approach to minimize atherogenesis and counteract inflammation.

Self-assembled cationic amphiphiles as antimicrobial peptides mimics: Role of hydrophobicity, linkage type, and assembly state

Inspired by high promise using naturally occurring antimicrobial peptides (AMPs) to treat infections caused by antimicrobial-resistant bacteria, cationic amphiphiles (CAms) were strategically designed as synthetic mimics to overcome associated limitations, including high manufacture cost and low metabolic stability. CAms with facially amphiphilic conformation were expected to demonstrate membrane-lytic properties and thus reduce tendency of resistance development. By systematically tuning the hydrophobicity, CAms with optimized compositions exhibited potent broad-spectrum antimicrobial activity (with minimum inhibitory concentrations in low μg/mL range) as well as negligible hemolytic activity. Electron microscope images revealed the morphological and ultrastructure changes of bacterial membranes induced by CAm treatment and validated their membrane-disrupting mechanism. Additionally, an all-atom molecular dynamics simulation was employed to understand the CAm-membrane interaction on molecular level. This study shows that these CAms can serve as viable scaffolds for designing next generation of AMP mimics as antimicrobial alternatives to combat drug-resistant pathogens.

pH-responsive amphiphilic macromolecular carrier for doxorubicin delivery

In this work, pH-sensitive amphiphilic macromolecules are designed to possess good biocompatibility and drug loading while employing an acid-sensitive linkage to trigger drug release at tumor tissues. Specifically, two pH-sensitive amphiphilic macromolecules were synthesized with a hydrazone linkage between the hydrophobic and hydrophilic segments. The chemical structure, molecular weight, critical micelle concentration, micelle size, and pH-triggered cleavage of the amphiphilic macromolecules were characterized via matrix-assisted laser desorption/ionization time-of-flight, nuclear magnetic resonance, and dynamic light scattering techniques. Drug loading and release as well as cytotoxicity studies were performed using doxorubicin. Hydrodynamic diameters of the micelles formed with pH-sensitive amphiphilic macromolecules were within an optimal range for cellular uptake. The critical micelle concentration values were 10–8–10–6 M, indicating micellar stability upon dilution. The degradation products of the amphiphilic macromolecules after acidic incubation were identified using mass spectrometry, nuclear magnetic resonance, and dynamic light scattering methods. A pH-dependent release profile of the doxorubicin-encapsulated amphiphilic macromolecules was observed. Cytotoxicity studies against two cancer cell lines, MDA-MB-231 human breast cancer cells and A549 lung cancer cells, showed that doxorubicin encapsulated in pH-sensitive amphiphilic macromolecules decreased cell viability more efficiently than free doxorubicin, possibly due to the toxicity of the amphiphilic macromolecule degradation products. Resulting from enhanced release at acidic pH due to hydrolysis of the hydrazone linkage, pH-sensitive amphiphilic macromolecules also had improved efficacy toward cancer cells compared to other carriers (e.g. Pluronics®). These findings indicate that pH-sensitive amphiphilic macromolecules can potentially be applied as anticancer drug delivery vehicles to achieve controlled release and improved therapeutic effects.

Micellar and structural stability of nanoscale amphiphilic polymers: Implications for anti-atherosclerotic bioactivity

Atherosclerosis, a leading cause of mortality in developed countries, is characterized by the buildup of oxidized low-density lipoprotein (oxLDL) within the vascular intima, unregulated oxLDL uptake by macrophages, and ensuing formation of arterial plaque. Amphiphilic polymers (AMPs) comprised of a branched hydrophobic domain and a hydrophilic poly(ethylene glycol) (PEG) tail have shown promising anti-atherogenic effects through direct inhibition of oxLDL uptake by macrophages. In this study, five AMPs with controlled variations were evaluated for their micellar and structural stability in the presence of serum and lipase, respectively, to develop underlying structure-atheroprotective activity relations. In parallel, molecular dynamics simulations were performed to explore the AMP conformational preferences within an aqueous environment. Notably, AMPs with ether linkages between the hydrophobic arms and sugar backbones demonstrated enhanced degradation stability and storage stability, and also elicited enhanced anti-atherogenic bioactivity. Additionally, AMPs with increased hydrophobicity elicited increased atheroprotective bioactivity in the presence of serum. These studies provide key insights for designing more serum-stable polymeric micelles as prospective cardiovascular nanotherapies.

Designing polymers with sugar-based advantages for bioactive delivery applications

Sugar-based polymers have been extensively explored as a means to increase drug delivery systems' biocompatibility and biodegradation. Here,we review he use of sugar-based polymers for drug delivery applications, with a particular focus on the utility of the sugar component(s) to provide benefits for drug targeting and stimuli responsive systems. Specifically, numerous synthetic methods have been developed to reliably modify naturally-occurring polysaccharides, conjugate sugar moieties to synthetic polymer scaffolds to generate glycopolymers, and utilize sugars as a multifunctional building block to develop sugar-linked polymers. The design of sugar-based polymer systems has tremendous implications on both the physiological and biological properties imparted by the saccharide units and are unique from synthetic polymers. These features include the ability of glycopolymers to preferentially target various cell types and tissues through receptor interactions, exhibit bioadhesion for prolonged residence time, and be rapidly recognized and internalized by cancer cells. Also discussed are the distinct stimuli-sensitive properties of saccharide-modified polymers to mediate drug release under desired conditions. Saccharide-based systems with inherent pH- and temperature-sensitive properties, as well as enzyme-cleavable polysaccharides for targeted bioactive delivery, are covered. Overall, this work emphasizes inherent benefits of sugar-containing polymer systems for bioactive delivery.