Novel natural osthole-inspired amphiphiles as membrane targeting antibacterials against methicillin-resistant Staphylococcus aureus (MRSA).

Methicillin-resistant Staphylococcus aureus (MRSA) is a widespread pathogen causing clinical infections and is multi-resistant to many antibiotics, making it urgent need to develop novel antibacterials to combat MRSA. Herein, we designed and prepared a series of novel osthole amphiphiles 6a-6ad by mimicking the structures and function of antimicrobial peptides (AMPs). Antibacterial assays showed that osthole amphiphile 6aa strongly inhibited S. aureus and 10 clinical MRSA isolates with MIC values of 1-2 µg/mL, comparable to that of the commercial antibiotic vancomycin. Additionally, 6aa had the advantages of rapid bacteria killing without readily developing drug resistance, low toxicity, good membrane selectivity, and good plasma stability. Mechanistic studies indicated that 6aa possesses good membrane-targeting ability to bind to phosphatidylglycerol (PG) on the bacterial cell membranes, thereby disrupting the cell membranes and causing an increase in intracellular ROS as well as leakage of proteins and DNA, and accelerating bacterial death. Notably, in vivo activity results revealed that 6aa exhibits strong anti-MRSA efficacy than vancomycin as well as a substantial reduction in MRSA-induced proinflammatory cytokines, including TNF-α and IL-6. Given the impressive in vitro and in vivo anti-MRSA efficacy of 6aa, which makes it a potential candidate against MRSA infections.

Detection and disaggregation of amyloid fibrils by luminescent amphiphilic platinum(II) complexes.

Cyclometallated Pt(II) complexes possessing hydrophobic 2-phenylpyridine (ppy) ligands and hydrophilic acetonylacetone (acac) ligands have been investigated for their ability to detect amyloid fibrils via luminescence response. Using hen egg-white lysozyme (HEWL) as a model amyloid protein, Pt(II) complexes featuring benzanilide-substituted ppy ligands and ethylene glycol-functionalized acac ligands demonstrated enhanced luminescence in the presence of HEWL fibrils, whereas Pt(II) complexes lacking complementary hydrophobic/hydrophilic ligand sets displayed little to no emission enhancement. An amphiphilic Pt(II) complex incorporating a bis(ethylene glycol)-derivatized acac ligand was additionally found to trigger restructuring of HEWL fibrils into smaller spherical aggregates. Amphiphilic Pt(II) complexes were generally non-toxic to SH-SY5Y neuroblastoma cells, and several complexes also exhibited enhanced luminescence in the presence of Aß42 fibrils associated with Alzheimer's disease. This study demonstrates that easily prepared and robust (ppy)PtII(acac) complexes show promising reactivity toward amyloid fibrils and represent attractive molecular scaffolds for design of small-molecule probes targeting amyloid assemblies.

Newly synthesized surfactants as antimicrobial and anti-adhesion agents.

Quaternary ammonium salts (QAS) are widely used in medicine, industry and agriculture as disinfectants, biocides, and fungicides. QAS have the ability to coat various surfaces, prevent adhesion of microorganisms to them and inhibit the formation of biofilm. A group of surfactants derived from benzoic acid with different chemical structures was tested: monomeric QAS with different alkyl chain lengths (C12, C14, C16), gemini QAS containing 12-carbon alkyl chains and linkers of various lengths (3,4,6 methylene groups), as well as multifunctional QAS. Among the tested surfactants, monomeric QAS showed the highest bactericidal and fungicidal activity. All three groups of tested compounds inhibited the filamentation of C. albicans. The best antimicrobial activity was demonstrated by the monomeric surfactant C12AA, while the multifunctional equivalent (2xC12AA) was characterized by good anti-adhesive activity. All tested compounds are non-mutagenic and cause low hemolysis of sheep erythrocytes. Multifunctional and gemini surfactants are also non-toxic.

Synthesis of calix (4) resorcinarene based amphiphilic macrocycle as an efficient nanocarrier for Amphotericin-B to enhance its oral bioavailability.

The supramolecular-based macrocyclic amphiphiles have fascinating attention and find extensive utilization in the pharmaceutical industry for efficient drug delivery. In this study, we designed and synthesized a new supramolecular amphiphilic macrocycle to serve as an efficient nanocarrier, achieved by treating 4-hydroxybenzaldehyde with 1-bromotetradecane. The derivatized product was subsequently treated with resorcinol to cyclize, resulting in the formation of a calix(4)-resorcinarene-based supramolecular amphiphilic macrocycle. The synthesized macrocycle and intermediate products were characterized using mass spectrometry, IR, and 1H NMR spectroscopic techniques. The amphotericin-B (Amph-B)-loaded and unloaded amphiphiles were screened for biocompatibility studies, vesicle formation, particle shape, size, surface charge, drug entrapment, in-vitro release profile, and stability through atomic force microscopy (AFM), Zetasizer, HPLC, and FT-IR. Amph-B -loaded macrocycle-based niosomal vesicles were investigated for in-vivo bioavailability in rabbits. The synthesized macrocycle exhibited no cytotoxicity against normal mouse fibroblast cells and was found to be hemocompatible and safe in mice following an acute toxicity study. The drug-loaded macrocycle-based vesicles appeared spherical, nano-sized, and homogeneous in size, with a notable negative surface charge. The vesicles remained stable after 30 days of storage. The results of Amph-B oral bioavailability and pharmacokinetics revealed that the newly tailored niosomal formulation enhanced drug solubility, protected drug degradation at gastric pH, facilitated sustained drug release at the specific target site, and delayed plasma drug clearance. Incorporating such advanced niosomal formulations in the field of drug delivery systems has the potential to revolutionize therapeutic outcomes and improve the quality of patient well-being.

Bioinspired, surfactant-free, dual-layer asymmetric structures based on polysaccharides, gelatin, and tannic acid for potential applications in biomedicine.

The formation of dual-layer asymmetric porous structures in surfactant-based systems is significantly influenced by emulsions. Surfactants self-assemble to alter the conformational arrangement of polysaccharides, while gravity disrupts the initial uniformity of the established equilibrium droplet concentration gradient in the emulsion, thus achieving delamination. Specifically, high-speed rotation and non-instantaneous freezing allow the gelatin solution to form two different states of foam layers. The integrated dual-layer asymmetric porous structure, composed of polysaccharides and tannic acid, is constructed with gelatin as a skeleton and surfactant. This innovative approach eliminates the need to consider the toxicity of chemically synthesized surfactants and expands the concept of gelatin utilization. This intriguing structure exhibits a variety of desirable characteristics within 30 days (e.g., tailorable performance, ultrarapid antioxidant activity, efficient antibacterial activity, low differential blood clotting index, and good hemocompatibility and cytocompatibility), suggesting its potential as a valuable reference for applying hierarchical porous structures, thereby offering more formulation flexibility for biomaterials with adjustable properties.

Preparation of novel shell-ionotropically crosslinked micelles based on hexadecylamine and tripolyphosphate for cancer drug delivery.

AIMS: Micellar systems have the advantage of being easily prepared, cheap, and readily loadable with bioactive molecular cargo. However, their fundamental pitfall is poor stability, particularly under dilution conditions. We propose to use simple quaternary ammonium surfactants, namely, hexadecylamine (HDA) and hexadecylpyridinium (HDAP), together with tripolyphosphate (TPP) anion, to generate ionotropically stabilized micelles capable of drug delivery into cancer cells. METHODS: optimized mixed HDA/HDAP micelles were prepared and stabilized with TPP. Curcumin was used as a loaded model drug. The prepared nanoparticles were characterized by dynamic light scattering, infrared spectroscopy, transmission electron microscopy, and differential scanning calorimetry. Moreover, their cellular uptake was assessed using flow cytometry and confocal fluorescence microscopy. RESULTS: The prepared nanoparticles were found to be stable under dilution and at high temperatures and to have a size range from 139 nm to 580 nm, depending on pH (4.6-7.4), dilution (up to 100 times), and temperature (25 - 80 °C). They were effective at delivering their load into cancer cells. Additionally, flow cytometry indicated the resulting stabilized micellar nanoparticles to be non-cytotoxic. CONCLUSIONS: The described novel stabilized micelles are simple to prepare and viable for cancer delivery.

Dual Functional Microcapsule based on Monodisperse Short PEG Amphiphile for Drug Encapsulation and Protein Affinity Controlled Release.

A short monodisperse poly(ethylene glycol) (PEG) and a neutral organic rotamer conjugate TEG-BTA-2 amphiphile was designed for the construction of a stimuli-responsive switchable self-assembled structure for drug encapsulation by noncovalent interaction and targeted controlled delivery. A short PEG, tetraethylene glycol (TEG) was covalently attached with a neutral organic rotamer benzothiazole dye (BTA-2) affording the neutral TEG-BTA-2 (<500 D). The TEG-BTA-2 is self-assembled into a microsphere in an aqueous medium, but remarkably undergoes morphology change switching to a rice-like microcapsule for curcumin encapsulation. Curcumin-loaded microcapsules were stable in an aqueous solution, however, were noticed disintegrating upon the addition of BSA protein. This is possibly due to an interaction with BSA protein leading to a protein affinity-controlled curcumin release in a neutral PBS buffer. Moreover, cell internalization of the neutral amphiphile TEG-BTA-2 into A549 cells was observed by fluorescence microscopy, providing an opportunity for application as a molecular vehicle for targeted drug delivery and monitoring.

A Fluorous Peptide Amphiphile with Potent Antimicrobial Activity for the Treatment of MRSA-induced Sepsis and Chronic Wound Infection.

The rising prevalence of global antibiotic resistance evokes the urgent need for novel antimicrobial candidates. Cationic lipopeptides have attracted much attention due to their strong antimicrobial activity, broad-spectrum and low resistance tendency. Herein, a library of fluoro-lipopeptide amphiphiles was synthesized by tagging a series of cationic oligopeptides with a fluoroalkyl tail via a disulfide spacer. Among the lipopeptide candidates, R6F bearing six arginine moieties and a fluorous tag shows the highest antibacterial activity, and it exhibits an interesting fluorine effect as compared to the non-fluorinated lipopeptides. The high antibacterial activity of R6F is attributed to its excellent bacterial membrane permeability, which further disrupts the respiratory chain redox stress and cell wall biosynthesis of the bacteria. By co-assembling with lipid nanoparticles, R6F showed high therapeutic efficacy and minimal adverse effects in the treatment of MRSA-induced sepsis and chronic wound infection. This work provides a novel strategy to design highly potent antibacterial peptide amphiphiles for the treatment of drug-resistant bacterial infections.

Chimeric Amphiphilic Disinfectants: Quaternary Ammonium/Quaternary Phosphonium Hybrid Structures.

Cationic biocides play a crucial role in the disinfection of domestic and healthcare surfaces. Due to the rise of bacterial resistance towards common cationic disinfectants like quaternary ammonium compounds (QACs), the development of novel actives is necessary for effective infection prevention and control. Toward this end, a series of 15 chimeric biscationic amphiphilic compounds, bearing both ammonium and phosphonium residues, were prepared to probe the structure and efficacy of mixed cationic ammonium-phosphonium structures. Compounds were obtained in two steps and good yields, with straightforward and chromatography-free purifications. Antibacterial activity evaluation of these compounds against a panel of seven bacterial strains, including two MRSA strains as well as opportunistic pathogen A. baumannii, were encouraging, as low micromolar inhibitory activity was observed for multiple structures. Alkyl chain length on the ammonium group was, as expected, a major determinant of bioactivity. In addition, high therapeutic indexes (up to 125-fold) for triphenyl phosphonium-bearing amphiphiles were observed when comparing antimicrobial activity to mammalian cell lysis activity.

Targeted Polymeric Nanoparticles Based on Mangiferin for Enhanced Protection of Pancreatic ß-Cells and Type 1 Diabetes Mellitus Efficacy.

Mangiferin (MGF) is found in many natural plants, such as Rhizoma Anemarrhenae, and has anti-diabetes effects. However, its clinical applications and development are limited by poor solubility and low-concentration enrichment in pancreatic islets. In this paper, targeted polymeric nanoparticles were constructed for MGF delivery with the desired drug loading content (6.86 ± 0.60%), excellent blood circulation, and missile-like delivery to the pancreas. Briefly, Glucagon-like peptide 1 (GLP-1) as an active targeting agent to the pancreas was immobilized on the block copolymer polyethyleneglycol-polycaprolactone (PEG-PCL) to obtain final GLP-1-PEG-PCL amphiphiles. Spherical MGF-loaded polymeric nanoparticles were acquired from the self-assembly of the targeted GDPP nanoparticles and MGF with a homogeneous size of 158.9 ± 1.7 nm and a negative potential for a good steady state in circulation. In this drug vehicle, GLP-1 acts as the missile vanguard via the GLP-1 receptor on the surface of the pancreas for improving the accumulation and efficiency of MGF in the pancreas, the hypoglycemic effect of MGF, and the restorative effect on pancreatic islets, which were investigated. As compared to free MGF, MGF/GDPP nanoparticles appeared to be more concentrated in the pancreas, with better blood glucose and glucose tolerance, enhanced insulin levels, increased ß-cell proliferation, reduced ß-cell apoptosis, and islet repair in vivo. This targeted drug delivery system provided a novel strategy and hope for enhancing MGF delivery and anti-diabetes efficacy.

CNSL, a Promising Building Blocks for Sustainable Molecular Design of Surfactants: A Critical Review.

Surfactants are crystallizing a certain focus for consumer interest, and their market is still expected to grow by 4 to 5% each year. Most of the time these surfactants are of petroleum origin and are not often biodegradable. Cashew Nut Shell Liquid (CNSL) is a promising non-edible renewable resource, directly extracted from the shell of the cashew nut. The interesting structure of CNSL and its components (cardanol, anacardic acid and cardol) lead to the synthesis of biobased surfactants. Indeed, non-ionic, anionic, cationic and zwitterionic surfactants based on CNSL have been reported in the literature. Even now, CNSL is absent or barely mentioned in specialized review or chapters talking about synthetic biobased surfactants. Thus, this review focuses on CNSL as a building block for the synthesis of surfactants. In the first part, it describes and criticizes the synthesis of molecules and in the second part, it compares the efficiency and the properties (CMC, surface tension, kraft temperature, biodegradability) of the obtained products with each other and with commercial ones.

Cationic amphiphilic dendrons with effective antibacterial performance.

Bacterial infections and antibiotic resistance have become a global healthcare crisis. Herein, we designed and synthesized a series of cationic amphiphilic dendrons with cationic dendrons and hydrophobic alkyl chains for potential antibacterial applications. Our results showed that the antimicrobial activities of the cationic amphiphilic dendrons were highly dependent upon the length of the hydrophobic alkyl chain, whereas the number of cationic charges was less important. Among these cationic amphiphilic dendrons, a prime candidate was identified, which possessed excellent antimicrobial activity against various pathogens (minimum inhibitory concentrations of 9, 3, and 3 µg mL-1 for Escherichia coli, Staphylococcus aureus, and methicillin-resistant Staphylococcus aureus, respectively). Scanning electron microscopy and fluorescence microscopy analyses showed that it could disrupt the integrity of a pathogen's membrane, leading to cell lysis and death. In addition, in vitro bacteria-killing kinetics showed that it had rapid bactericidal efficiency. It also had excellent antimicrobial activities against MRSA in vivo and promoted wound healing. In general, the synthesized cationic amphiphilic dendrons, which exhibited rapid and broad-spectrum bactericidal activity, may have great potential in antimicrobial applications.

Surfactant Effect on the Physicochemical Characteristics of Solid Lipid Nanoparticles Based on Pillar[5]arenes.

Novel monosubstituted pillar[5]arenes containing both amide and carboxyl functional groups were synthesized. Solid lipid nanoparticles based on the synthesized macrocycles were obtained. Formation of spherical particles with an average hydrodynamic diameter of 250 nm was shown for pillar[5]arenes containing N-(amidoalkyl)amide fragments regardless of their concentration. It was established that pillar[5]arene containing N-alkylamide fragments can form spherical particles with two different sizes (88 and 223 nm) depending on its concentration. Mixed solid lipid nanoparticles based on monosubstituted pillar[5]arenes and surfactant (dodecyltrimethylammonium chloride) were obtained for the first time. The surfactant made it possible to level the effect of the macrocycle concentration. It was found that various types of aggregates are formed depending on the macrocycle/surfactant ratio. Changing the macrocycle/surfactant ratio allows to control the charge of the particles surface. This controlled property will lead to the creation of molecular-scale porous materials that selectively interact with various types of substrates, including biopolymers.

Amphiphilic quaternized chitosan: Synthesis, characterization, and anti-cariogenic biofilm property.

Hydrophobized chitosan derivatives, hexyl chitosan (HCS), dodecyl chitosan (DCS), and phthaloyl chitosan (PhCS) of approximately 30 and 50% degree of substitution (%DS) reacted with glycidyltrimethylammonium chloride (GTMAC) to incorporate hydrophilic positively charged groups of N-[(2-hydroxyl-3-trimethylammonium)propyl] and yielded amphiphilic quaternized chitosan derivatives. They can assemble into spherical nanoparticles with a hydrodynamic diameter of ~100-300 nm and positive ζ-potential values (+15 to +56). Their anti-biofilm efficacy was evaluated against the dental caries pathogen, Streptococcus mutans. Among all derivatives, the one having 30%DS of hexyl group and prepared by reacting with 1 mol equivalent of GTMAC (H30CS-GTMAC) showed the best performance in terms of its aqueous solubility, the lowest minimum inhibitory concentration (138 µg/mL) and the minimum bactericidal concentration (275 µg/mL) which are superior to the unmodified chitosan. Its equivalent anti-biofilm efficacy to that of chlorhexidine suggests that it can be a greener antibacterial agent for oral care formulations.

Phosphonodithioester-Amine Coupling as a Key Reaction Step for the Design of Cationic Amphiphiles Used for Gene Delivery.

A convergent synthesis of cationic amphiphilic compounds is reported here with the use of the phosphonodithioester-amine coupling (PAC) reaction. This versatile reaction occurs at room temperature without any catalyst, allowing binding of the lipid moiety to a polar head group. This strategy is illustrated with the use of two lipid units featuring either two oleyl chains or two-branched saturated lipid chains. The final cationic amphiphiles were evaluated as carriers for plasmid DNA delivery in four cell lines (A549, Calu3, CFBE and 16HBE) and were compared to standards (BSV36 and KLN47). These new amphiphilic derivatives, which were formulated with DOPE or DOPE-cholesterol as helper lipids, feature high transfection efficacies when associated with DOPE. The highest transfection efficacies were observed in the four cell lines at low charge ratios (CR = 0.7, 1 or 2). At these CRs, no toxic effects were detected. Altogether, this new synthesis scheme using the PAC reaction opens up new possibilities for investigating the effects of lipid or polar head groups on transfection efficacies.

Antimicrobial Properties and Cytotoxic Effect of Imidazolium Geminis with Tunable Hydrophobicity.

Antimicrobial, membranotropic and cytotoxic properties of dicationic imidazolium surfactants of n-s-n (Im) series with variable length of alkyl group (n = 8, 10, 12, 14, 16) and spacer fragment (s = 2, 3, 4) were explored and compared with monocationic analogues. Their activity against a representative range of Gram-positive and Gram-negative bacteria, and also fungi, is characterized. The relationship between the biological activity and the structural features of these compounds is revealed, with the hydrophobicity emphasized as a key factor. Among dicationic surfactants, decyl derivatives showed highest antimicrobial effect, while for monocationic analogues, the maximum activity is observed in the case of tetradecyl tail. The leading compounds are 2-4 times higher in activity compared to reference antibiotics and prove effective against resistant strains. It has been shown that the antimicrobial effect is not associated with the destruction of the cell membrane, but is due to specific interactions of surfactants and cell components. Importantly, they show strong selectivity for microorganism cells while being of low harm to healthy human cells, with a SI ranging from 30 to 100.

Molecular Insight into the ß-Sheet Twist and Related Morphology of Self-Assembled Peptide Amphiphile Ribbons.

Self-assembly of high-aspect-ratio filaments containing ß-sheets has attracted much attention due to potential use in bioengineering and biomedicine. However, precisely predicting the assembled morphologies remains a grand challenge because of insufficient understanding of the self-assembly process. We employed an atomistic model to study the self-assembly of peptide amphiphiles (PAs) containing valine-glutamic acid (VE) dimeric repeats. By changing of the sequence length, the assembly morphology changes from flat ribbon to left-handed twisted ribbon, implying a relationship between ß-sheet twist and strength of interstrand hydrogen bonds. The calculations are used to quantify this relationship including both magnitude and sign of the ribbon twist angle. Interestingly, a change in chirality is observed when we introduce the RGD epitope into the C-terminal of VE repeats, suggesting arginine and glycine's role in suppressing right-handed ß-sheet formation. This study provides insight into the relationship between ß-sheet twist and self-assembled nanostructures including a possible design rule for PA self-assembly.

Modular amphiphilic poly(aryl ether)-based supramolecular nanomicelles: an efficient endocytic drug carrier.

A rationally designed amphiphilic poly(aryl ether)-based dendrimer self-assembles into nanomicelles and exhibits tunable morphology upon varying the hydrophilic chain length. The 30 nm-sized dendrimer nanomicelles successfully entrapped Doxorubicin, demonstrated the sustained release of Doxorubicin and can successfully penetrate cancer cells through caveolae-dependent endocytosis, compared to the free drug.

Supramolecular Drug Delivery System from Macrocycle-Based Self-Assembled Amphiphiles for Effective Tumor Therapy.

Intelligent drug delivery systems (DDSs) that can improve therapeutic outcomes of antitumor agents and decrease their side effects are urgently needed to satisfy special requirements of treatment of malignant tumors in clinics. Here, the fabrication of supramolecular self-assembled amphiphiles based on the host-guest recognition between a cationic water-soluble pillar[6]arene (WP6A) host and a sodium decanesulfonate guest (G) is reported. The chemotherapeutic agent doxorubicin hydrochloride (DOX) can be encapsulated into the formed vesicle (G/WP6A) to construct supramolecular DDS (DOX@G/WP6A). WP6A affords strong affinities to G to avoid undesirable off-target leakage during delivery. Nanoscaled DOX@G/WP6A is capable of preferentially accumulating in tumor tissue via enhanced permeability and retention (EPR) effect. After internalization by tumor cells, the abundant adenosine triphosphate (ATP) binds competitively with WP6A to trigger the disintegration of self-assembled vesicles with the ensuing release of DOX. In vitro and in vivo research confirmed that DOX@G/WP6A is not only able to promote antitumor efficacy but also reduce DOX-related systemic toxicity. The above favorable findings are ascribed to the formation of ternary self-assembly, which profits from the combination of the factors of the EPR effect and the ATP-triggered release.

Generation and Characterization of a Library of Novel Biologically Active Functional Surfactants (Surfmers) Using Combined High-Throughput Methods.

We report the first successful combination of three distinct high-throughput techniques to deliver the accelerated design, synthesis, and property screening of a library of novel, bio-instructive, polymeric, comb-graft surfactants. These three-dimensional, surface-active materials were successfully used to control the surface properties of particles by forming a unimolecular deep layer on the surface of the particles via microfluidic processing. This strategy deliberately utilizes the surfactant to both create the stable particles and deliver a desired cell-instructive behavior. Therefore, these specifically designed, highly functional surfactants are critical to promoting a desired cell response. This library contained surfactants constructed from 20 molecularly distinct (meth)acrylic monomers, which had been pre-identified by HT screening to exhibit specific, varied, and desirable bacterial biofilm inhibitory responses. The surfactant's self-assembly properties in water were assessed by developing a novel, fully automated, HT method to determine the critical aggregation concentration. These values were used as the input data to a computational-based evaluation of the key molecular descriptors that dictated aggregation behavior. Thus, this combination of HT techniques facilitated the rapid design, generation, and evaluation of further novel, highly functional, cell-instructive surfaces by application of designed surfactants possessing complex molecular architectures.