RESUMO
Cartilages are unique in the family of connective tissues in that they contain a high concentration of the glycosaminoglycans, chondroitin sulfate and keratan sulfate attached to the core protein of the proteoglycan, aggrecan. Multiple aggrecan molecules are organized in the extracellular matrix via a domain-specific molecular interaction with hyaluronan and a link protein, and these high molecular weight aggregates are immobilized within the collagen and glycoprotein network. The high negative charge density of glycosaminoglycans provides hydrophilicity, high osmotic swelling pressure and conformational flexibility, which together function to absorb fluctuations in biomechanical stresses on cartilage during movement of an articular joint. We have summarized information on the history and current knowledge obtained by biochemical and genetic approaches, on cell-mediated regulation of aggrecan metabolism and its role in skeletal development, growth as well as during the development of joint disease. In addition, we describe the pathways for hyaluronan metabolism, with particular focus on the role as a "metabolic rheostat" during chondrocyte responses in cartilage remodeling in growth and disease.Future advances in effective therapeutic targeting of cartilage loss during osteoarthritic diseases of the joint as an organ as well as in cartilage tissue engineering would benefit from 'big data' approaches and bioinformatics, to uncover novel feed-forward and feed-back mechanisms for regulating transcription and translation of genes and their integration into cell-specific pathways.
Assuntos
Cartilagem Articular , Ácido Hialurônico , Agrecanas/genética , Agrecanas/análise , Agrecanas/metabolismo , Ácido Hialurônico/metabolismo , Polieletrólitos/análise , Polieletrólitos/metabolismo , Polieletrólitos/farmacologia , Cartilagem Articular/metabolismo , Proteínas da Matriz Extracelular/metabolismo , Glicosaminoglicanos , Lectinas Tipo C/metabolismoRESUMO
Highly charged intrinsically disordered proteins are essential regulators of chromatin structure and transcriptional activity. Here we identify a surprising mechanism of molecular competition that relies on the pronounced dynamical disorder present in these polyelectrolytes and their complexes. The highly positively charged human linker histone H1.0 (H1) binds to nucleosomes with ultrahigh affinity, implying residence times incompatible with efficient biological regulation. However, we show that the disordered regions of H1 retain their large-amplitude dynamics when bound to the nucleosome, which enables the highly negatively charged and disordered histone chaperone prothymosin α to efficiently invade the H1-nucleosome complex and displace H1 via a competitive substitution mechanism, vastly accelerating H1 dissociation. By integrating experiments and simulations, we establish a molecular model that rationalizes the remarkable kinetics of this process structurally and dynamically. Given the abundance of polyelectrolyte sequences in the nuclear proteome, this mechanism is likely to be widespread in cellular regulation.
Assuntos
Histonas/metabolismo , Proteínas Intrinsicamente Desordenadas/metabolismo , Nucleossomos/metabolismo , Polieletrólitos/metabolismo , HumanosRESUMO
Engineering microenvironments for sequential enzymatic reactions has attracted specific interest within different fields of research as an effective strategy to improve the catalytic performance of enzymes. While in industry most enzymatic reactions occur in a single compartment carrier, living cells are however able to conduct multiple reactions simultaneously within confined sub-compartments, or organelles. Engineering multi-compartments with regulated environments and transformation properties enhances enzyme activity and stability and thus increases the overall yield of final products. In this review, we discuss current and potential methods to fabricate artificial cells for sequential enzymatic reactions, which are inspired by mechanisms and metabolic pathways developed by living cells. We aim to advance the understanding of living cell complexity and its compartmentalization and present solutions to mimic these processes in vitro. Particular attention has been given to layer-by-layer assembly of polyelectrolytes for developing multi-compartments. We hope this review paves the way for the next steps toward engineering of smart artificial multi-compartments with adoptive stimuli-responsive properties, mimicking living cells to improve catalytic properties and efficiency of the enzymes and enhance their stability.
Assuntos
Reatores Biológicos , Organelas , Redes e Vias Metabólicas , Organelas/metabolismo , Polieletrólitos/metabolismoRESUMO
The present study focuses on the immobilization of the bacterial ribonuclease barnase (Bn) into submicron porous calcium carbonate (CaCO3) particles. For encapsulation, we apply adsorption, freezing-induced loading and co-precipitation methods and study the effects of adsorption time, enzyme concentration and anionic polyelectrolytes on the encapsulation efficiency of Bn. We show that the use of negatively charged dextran sulfate (DS) and ribonucleic acid from yeast (RNA) increases the loading capacity (LC) of the enzyme on CaCO3 particles by about 3-fold as compared to the particles with Bn itself. The ribonuclease (RNase) activity of encapsulated enzyme depends on the LC of the particles and transformation of metastable vaterite to stable calcite, as studied by the assessment of enzyme activities in particles.
Assuntos
Proteínas de Bactérias/química , Carbonato de Cálcio/química , Polieletrólitos/química , Ribonucleases/química , Adsorção , Proteínas de Bactérias/biossíntese , Proteínas de Bactérias/metabolismo , Carbonato de Cálcio/metabolismo , Sulfato de Dextrana/química , Sulfato de Dextrana/metabolismo , Escherichia coli/enzimologia , Tamanho da Partícula , Polieletrólitos/metabolismo , Porosidade , RNA/química , RNA/metabolismo , Ribonucleases/biossíntese , Ribonucleases/metabolismo , Saccharomyces cerevisiae/química , Saccharomyces cerevisiae/metabolismo , Propriedades de SuperfícieRESUMO
The assembly of a hexameric lattice of retroviral immature particles requires the involvement of cell factors such as proteins and small molecules. A small, negatively charged polyanionic molecule, myo-inositol hexaphosphate (IP6), was identified to stimulate the assembly of immature particles of HIV-1 and other lentiviruses. Interestingly, cryo-electron tomography analysis of the immature particles of two lentiviruses, HIV-1 and equine infectious anemia virus (EIAV), revealed that the IP6 binding site is similar. Based on this amino acid conservation of the IP6 interacting site, it is presumed that the assembly of immature particles of all lentiviruses is stimulated by IP6. Although this specific region for IP6 binding may be unique for lentiviruses, it is plausible that other retroviral species also recruit some small polyanion to facilitate the assembly of their immature particles. To study whether the assembly of retroviruses other than lentiviruses can be stimulated by polyanionic molecules, we measured the effect of various polyanions on the assembly of immature virus-like particles of Rous sarcoma virus (RSV), a member of alpharetroviruses, Mason-Pfizer monkey virus (M-PMV) representative of betaretroviruses, and murine leukemia virus (MLV), a member of gammaretroviruses. RSV, M-PMV and MLV immature virus-like particles were assembled in vitro from truncated Gag molecules and the effect of selected polyanions, myo-inostol hexaphosphate, myo-inositol, glucose-1,6-bisphosphate, myo-inositol hexasulphate, and mellitic acid, on the particles assembly was quantified. Our results suggest that the assembly of immature particles of RSV and MLV was indeed stimulated by the presence of myo-inostol hexaphosphate and myo-inositol, respectively. In contrast, no effect on the assembly of M-PMV as a betaretrovirus member was observed.
Assuntos
Membrana Celular/química , Membrana Celular/metabolismo , Interações Hospedeiro-Patógeno , Polieletrólitos/química , Retroviridae/fisiologia , Montagem de Vírus , Alpharetrovirus/fisiologia , Animais , Betaretrovirus/fisiologia , Células Cultivadas , Gammaretrovirus/fisiologia , Produtos do Gene gag/química , Produtos do Gene gag/metabolismo , Polieletrólitos/metabolismo , Retroviridae/ultraestrutura , VírionRESUMO
We hypothesize that polycations, such as nuclear histones, released by neutrophils COVID-19 aggravate COVID-19 by multiple mechanisms: (A) Neutralization of the electrostatic repulsion between the virus particles and the cell membrane, thereby enhancing receptor-mediated entry. (B) Binding to the virus particles, thereby inducing opsonin-mediated endocytosis. (C) Adding to the cytotoxicity, in conjunction with oxidants, cytokines and other pro-inflammatory substances secreted by cells of the innate immunity system. These effects may be alleviated by the administration of negatively charged polyanions such as heparins and heparinoids.
Assuntos
COVID-19/etiologia , COVID-19/metabolismo , Modelos Biológicos , Polieletrólitos/metabolismo , Antivirais/uso terapêutico , Endocitose , Heparina/uso terapêutico , Histonas/metabolismo , Humanos , Imunidade Inata , Neutrófilos/metabolismo , Pandemias , Polieletrólitos/uso terapêutico , SARS-CoV-2/efeitos dos fármacos , SARS-CoV-2/patogenicidade , SARS-CoV-2/fisiologia , Eletricidade Estática , Internalização do Vírus , Tratamento Farmacológico da COVID-19RESUMO
The counterions neutralizing the charges on polyelectrolytes such as DNA or heparin may dissociate in water and greatly influence the interaction of such polyelectrolytes with biomolecules, particularly proteins. In this Review we give an overview of studies on the interaction of proteins with polyelectrolytes and how this knowledge can be used for medical applications. Counterion release was identified as the main driving force for the binding of proteins to polyelectrolytes: Patches of positive charge become multivalent counterions of the polyelectrolyte and lead to the release of counterions from the polyelectrolyte and a concomitant increase in entropy. This is shown from investigations on the interaction of proteins with natural and synthetic polyelectrolytes. Special emphasis is paid to sulfated dendritic polyglycerols (dPGS). The Review demonstrates that we are moving to a better understanding of charge-charge interactions in systems of biological relevance. Research along these lines will aid and promote the design of synthetic polyelectrolytes for medical applications.
Assuntos
DNA/química , Polieletrólitos/química , Proteínas/química , Antineoplásicos/química , Antineoplásicos/farmacologia , Sobrevivência Celular/efeitos dos fármacos , DNA/metabolismo , Portadores de Fármacos/química , Glicosaminoglicanos/química , Glicosaminoglicanos/metabolismo , Humanos , Polieletrólitos/metabolismo , Ligação Proteica , Proteínas/metabolismo , TermodinâmicaRESUMO
Alkaline phosphatase (ALP) responsive polymers, which can unzip from head to tail are reported. Hydrophilic and hydrophobic modification of the polymer was carried out for the formation of a polyelectrolyte complex and an amphiphilic nanoassembly, respectively, which offered distinct enzyme-triggered disassembly kinetics.
Assuntos
Fosfatase Alcalina/metabolismo , Nanopartículas/química , Polieletrólitos/metabolismo , Polímeros/metabolismo , Interações Hidrofóbicas e Hidrofílicas , Cinética , Polieletrólitos/química , Polímeros/químicaRESUMO
Many gaps in our understanding of Alzheimer's disease remain despite intense research efforts. One such prominent gap is the mechanism of Tau condensation and fibrillization. One viewpoint is that positively charged Tau is condensed by cytosolic polyanions. However, this hypothesis is likely based on an overestimation of the abundance and stability of cytosolic polyanions and an underestimation of crucial intracellular constituents - the cationic polyamines. Here, we propose an alternative mechanism grounded in cellular biology. We describe extensive molecular dynamics simulations and analysis on physiologically relevant model systems, which suggest that it is not positively charged, unmodified Tau that is condensed by cytosolic polyanions but negatively charged, hyperphosphorylated Tau that is condensed by cytosolic polycations. Our work has broad implications for anti-Alzheimer's research and drug development and the broader field of tauopathies in general, potentially paving the way to future etiologic therapies.
Assuntos
Doença de Alzheimer/metabolismo , Poliaminas Biogênicas/efeitos adversos , Proteínas tau/metabolismo , Poliaminas Biogênicas/química , Citosol/metabolismo , Humanos , Modelos Biológicos , Simulação de Dinâmica Molecular , Fosforilação , Poliaminas/metabolismo , Polieletrólitos/metabolismo , Agregação Patológica de Proteínas/etiologia , Agregação Patológica de Proteínas/metabolismo , Tauopatias , Proteínas tau/efeitos dos fármacosRESUMO
The luteinizing hormone receptor (LHR), a G protein-coupled receptor (GPCRs), can initiate signaling in the presence of some vanadium-containing compounds as a result of vanadium compound interactions with the membrane lipids and/or the cell membrane lipid interface. The ability of LHR expressed in CHO cells to initiate signaling in the presence of highly charged and water-soluble polyoxovanadates (POV) including Na3[H3V10O28] (V10) and two mixed-valence heteropolyoxovanadates, K(NH4)4[H6V14O38(PO4)]·11H2O (V14) and [(CH3)4N]6[V15O36(Cl)] (V15), was investigated here. Interactions of the vanadium compounds with CHO cells decreased the packing of membrane lipids, drove aggregation of LHR and increased signal transduction by LHR. Cell responses were comparable to, or in the case of V14 and V15, greater than those seen for cells treated with human chorionic gonadotropin (hCG), a naturally-occurring LHR ligand produced in early pregnancy in humans. POV effects were observed for CHO cells where LHR was expressed at 10 000 or 32 000 LHR per cell but not when LHR was overexpressed with receptor numbers >100 000 LHR per cell. To determine which POV species were present in the cell medium during cell studies, the speciation of vanadate (V1), V10, V14 or V15 in cell medium was monitored using 51V NMR and EPR spectroscopies. We found that all the POVs initiated signaling, but V15 and V10 had the greatest effects on cell function, while V1 was significantly less active. However, because of the complex nature of vanadium compounds speciation, the effects on cell function may be due to vanadium species formed in the cell medium over time.
Assuntos
Ânions/metabolismo , Polieletrólitos/metabolismo , Receptores Acoplados a Proteínas G/metabolismo , Compostos de Vanádio/metabolismo , Animais , Células CHO , Membrana Celular/metabolismo , Gonadotropina Coriônica/metabolismo , Cricetulus , Espectroscopia de Ressonância de Spin Eletrônica , Espectroscopia de Ressonância Magnética , Receptores Acoplados a Proteínas G/genética , Vanadatos/metabolismoRESUMO
The distinguished property of the physiological polymer, inorganic polyphosphate (polyP), is to act as a bio-intelligent material which releases stimulus-dependent metabolic energy to accelerate wound healing. This characteristic is based on the bio-imitating feature of polyP to be converted, upon exposure to peptide-containing body fluids, from stable amorphous nanoparticles to a physiologically active and energy-delivering coacervate phase. This property of polyP has been utilized to fabricate a wound mat consisting of compressed collagen supplemented with amorphous polyP particles, formed from the inorganic polyanion with an over-stoichiometric ratio of zinc ions. The proliferation and the migration of human skin keratinocytes in those matrices were investigated. If the cells were embedded into the mat they respond with a significantly higher motility when zinc-polyP particles are present. Interestingly, only keratinocytes that were grown in a polyP environment developed well-structured microvilli, reflecting an increased biological activity. The data show that Zn-polyP particles incorporated into wound mats are a potent cell growth and cell migration-stimulating inorganic bio-material.
Assuntos
Colágeno/química , Nanopartículas/química , Polieletrólitos/química , Polifosfatos/química , Zinco/química , Movimento Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Colágeno/metabolismo , Bandagens Compressivas , Epiderme/efeitos dos fármacos , Humanos , Queratinócitos/citologia , Polieletrólitos/metabolismo , Polifosfatos/metabolismo , Cicatrização/efeitos dos fármacos , Zinco/metabolismoRESUMO
We report for the first time that the protonation behavior of weak polyelectrolyte brushes depends very strongly on ionic strength. The pKa changes by one pH step per order of magnitude in salt concentration. For low salt concentrations (â¼1 mM), a very high pH is required to deprotonate a polyacidic brush and a very low pH is required to protonate a polybasic brush. This has major consequences for interactions with other macromolecules, as the brushes are actually almost fully neutral when believed to be charged. We propose that many previous studies on electrostatic interactions between polyelectrolytes and proteins have, in fact, looked at other types of intermolecular forces, in particular, hydrophobic interactions and hydrogen bonds.
Assuntos
Proteínas Imobilizadas/química , Polieletrólitos/química , Ligação de Hidrogênio , Concentração de Íons de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Proteínas Imobilizadas/metabolismo , Concentração Osmolar , Polieletrólitos/metabolismo , Ligação ProteicaRESUMO
Multilayered coated liposomes were prepared using the layer-by-layer (LbL) technique in an effort to improve their stability in biological media. The formulation strategy was based on the alternate deposition of two biocompatible and biodegradable polyelectrolytes - poly(L-lysine) (PLL) and poly(L-glutamic acid) (PGA) - on negatively charged small unilamellar vesicles (SUVs). Some parameters of the formulation process were optimized such as the polyelectrolyte concentration and the purification procedure. This optimized procedure has allowed the development of very homogeneous formulations of liposomes coated with up to 6 layers of polymers (so-called layersomes). The coating was characterized by dynamic light scattering (DLS), zeta potential measurements and Förster resonance energy transfer (FRET) between two fluorescently labeled polyelectrolytes. Studies on the stability of the formulations at 4 °C in a buffered solution have shown that most structures are stable over 1 month without impacting their encapsulation capacity. In addition, fluorophore release experiments have demonstrated a better resistance of the layersomes in the presence of a non-ionic detergent (Triton™ X-100) as well as in the presence of phospholipase A2 and human plasma. In conclusion, new multilayered liposomes have been developed to increase the stability of conventional liposomes in biological environments.
Assuntos
Química Farmacêutica , Polieletrólitos/química , Ácido Poliglutâmico/química , Polilisina/química , Sistemas de Liberação de Medicamentos , Estabilidade de Medicamentos , Armazenamento de Medicamentos , Humanos , Lipossomos , Octoxinol/química , Fosfolipases A2/metabolismo , Polieletrólitos/metabolismo , Ácido Poliglutâmico/metabolismo , Polilisina/metabolismoRESUMO
Cell-to-cell transmission of misfolding-prone α-synuclein (α-Syn) has emerged as a key pathological event in Parkinson's disease. This process is initiated when α-Syn-bearing fibrils enter cells via clathrin-mediated endocytosis, but the underlying mechanisms are unclear. Using a CRISPR-mediated knockout screen, we identify SLC35B2 and myosin-7B (MYO7B) as critical endocytosis regulators for α-Syn preformed fibrils (PFFs). We show that SLC35B2, as a key regulator of heparan sulfate proteoglycan (HSPG) biosynthesis, is essential for recruiting α-Syn PFFs to the cell surface because this process is mediated by interactions between negatively charged sugar moieties of HSPGs and clustered K-T-K motifs in α-Syn PFFs. By contrast, MYO7B regulates α-Syn PFF cell entry by maintaining a plasma membrane-associated actin network that controls membrane dynamics. Without MYO7B or actin filaments, many clathrin-coated pits fail to be severed from the membrane, causing accumulation of large clathrin-containing "scars" on the cell surface. Intriguingly, the requirement for MYO7B in endocytosis is restricted to α-Syn PFFs and other polycation-bearing cargos that enter cells via HSPGs. Thus, our study not only defines regulatory factors for α-Syn PFF endocytosis, but also reveals a previously unknown endocytosis mechanism for HSPG-binding cargos in general, which requires forces generated by MYO7B and actin filaments.
Assuntos
Endocitose/fisiologia , Miosinas/química , Miosinas/metabolismo , Polieletrólitos/metabolismo , alfa-Sinucleína/metabolismo , Linhagem Celular , Clatrina/metabolismo , Técnicas de Inativação de Genes , Células HEK293 , Humanos , Modelos Moleculares , Doença de Parkinson/metabolismo , Conformação Proteica , Transportadores de Sulfato/genética , Transportadores de Sulfato/metabolismoRESUMO
Antibiotic-polyelectrolyte nanoparticle complex (or nanoplex in short) has been recently demonstrated as a superior antibiotic delivery system to the native antibiotic in bronchiectasis therapy owed to its ability to overcome the lung's mucus barrier and generate high localized antibiotic exposure in the infected sites. The present work aimed to further improve the mucus permeability, hence the antibacterial efficacy of the nanoplex, by incorporating mucolytic enzyme papain (PAP) at the nanoplex formation step to produce PAP-decorated antibiotic-polyelectrolyte nanoplex exhibiting built-in mucolytic capability. Ciprofloxacin (CIP) and dextran sulfate (DXT) were used as the models for antibiotics and polyelectrolyte, respectively. The results showed that the PAP inclusion had minimal effects on the physical characteristics, preparation efficiency, and dissolution of the CIP-DXT nanoplex. The optimal CIP-(DXT-PAP) nanoplex exhibited size and zeta potential of approximately 200â¯nm and -50â¯mV with CIP and PAP payloads of 60% and 32% (w/w), respectively. The nanoplex was prepared at high efficiency with larger than 80% CIP and PAP utilization rates. The CIP-(DXT-PAP) nanoplex exhibited tenfold improvement in the mucus permeability compared to its CIP-DXT nanoplex counterpart, resulting in the former's superior bactericidal activity against clinical Pseudomonas aeruginosa biofilm in the presence of mucus barrier. A trade-off, nevertheless, existed between antibacterial efficacy and cytotoxicity towards human lung epithelium cells upon the incorporation of PAP above a certain concentration threshold. Therefore, the optimal dosing of the CIP-(DXT-PAP) nanoplex must be carefully determined.
Assuntos
Antibacterianos/farmacologia , Bronquiectasia/tratamento farmacológico , Ciprofloxacina/farmacologia , Sulfato de Dextrana/farmacologia , Nanopartículas/química , Papaína/química , Polieletrólitos/farmacologia , Antibacterianos/química , Antibacterianos/metabolismo , Biofilmes/efeitos dos fármacos , Bronquiectasia/microbiologia , Ciprofloxacina/química , Ciprofloxacina/metabolismo , Sulfato de Dextrana/química , Sulfato de Dextrana/metabolismo , Sistemas de Liberação de Medicamentos , Humanos , Testes de Sensibilidade Microbiana , Nanopartículas/metabolismo , Papaína/metabolismo , Tamanho da Partícula , Polieletrólitos/química , Polieletrólitos/metabolismo , Pseudomonas aeruginosa/efeitos dos fármacos , Propriedades de SuperfícieRESUMO
The adsorption of proteins to silica surface is a common process mainly governed by the electrostatic attractive interaction between the pH-dependent negatively silica surface and the positive charges of the biomolecule. This process often reduces the conformational stability of the adsorbed protein and may reduce its biological functionality mostly due to multimolecular processes such as aggregation and fibrillation. Here we show that high-density charge cationic polyelectrolytes may successfully compete with the protein for the silica surface containing deprotonated-silanol groups. Therefore, the coating of silica surfaces with these cationic polyelectrolytes precludes the adsorption of the protein to the solid surface. Intensive water washing of the polyelectrolyte-coated silica surfaces had does not result in polyelectrolyte release (even at moderate ionic strength) maintaining the solid surface protected from protein adsorption.
Assuntos
Polieletrólitos/química , Proteínas/química , Proteínas/metabolismo , Dióxido de Silício/química , Adsorção , Ligação Competitiva , Humanos , Concentração Osmolar , Polieletrólitos/metabolismo , Dióxido de Silício/metabolismo , Eletricidade Estática , Propriedades de SuperfícieRESUMO
Nowadays, nucleic acid-based therapy has become a promising way for the treatment of various malignant diseases like cancers. However, the process of nucleic acid delivery is hampered by several extracellular and intracellular obstacles. To overcome these obstacles, many nucleic acid delivery carriers have been developed to achieve improved safety and enhanced gene transfection performance. Among these carriers, degradable branched polycations have attracted much attention due to their good responsive degradability and impressive transfection performances. In this review, we mainly summarized the redox- and pH-responsive degradable branched polycationic systems used for nucleic acid delivery. For responsive degradable branched polycationic systems, the preparation methods were introduced, where amino-epoxy ring-opening reaction as a novel step growth approach was mainly presented. The properties of redox- and pH-responsive degradable branched polycationic systems were subsequently introduced and highlighted. We hope this brief review will motivate the delicate design of responsive degradable branched polycationic systems for potential clinical applications. This article is categorized under: Biology-Inspired Nanomaterials > Nucleic Acid-Based Structures.
Assuntos
Materiais Biocompatíveis , Técnicas de Transferência de Genes , Nanoestruturas , Ácidos Nucleicos , Polieletrólitos , Células A549 , Aminas , Compostos de Epóxi , Células HEK293 , Humanos , Concentração de Íons de Hidrogênio , Ácidos Nucleicos/química , Ácidos Nucleicos/metabolismo , Oxirredução , Polieletrólitos/química , Polieletrólitos/metabolismoRESUMO
Raman mapping is becoming a very useful tool in investigating cells and cellular components, as well as bioactive molecules intracellularly. In this study, we have encapsulated beta-carotene using a layer-by-layer technique, as a way to enhance its stability and bioavailability. Further, we have used Raman mapping to characterize the as-obtained capsules and monitor their uptake by the human retinal epithelial D407 cells. We were able to successfully map the beta-carotene distribution inside the capsules, to localize the capsules intracellularly, and distinguish between capsules and other cellular components.
Assuntos
Endocitose , Polieletrólitos/metabolismo , Análise Espectral Raman , beta Caroteno/metabolismo , Cápsulas , Linhagem Celular , Humanos , Análise de Componente PrincipalRESUMO
Previously, we reported on the surfactant cetylpyridinium chloride (CPC) as a crosslinker of alginate for the formation of stable polyelectrolyte-surfactant-complex nanoparticles. Here, we evaluate this system for increased solubility of a poorly soluble drug. The aim was to use CPC for solubilisation of ibuprofen and to use the micellar associates formed for alginate complexation and nanoparticle formation. We acquired deeper insights into the entropy led interactions between alginate, CPC and ibuprofen. Stable nanoparticles were formed across limited surfactant-to-polyelectrolyte molar ratios, with ~150 nm hydrodynamic diameter, monodispersed distribution, and negative zeta potential (-40 mV), with 34% ibuprofen loading. Their structure was obtained using small-angle X-ray scattering, which indicated disordered micellar associates when ibuprofen was incorporated. This resulted in nanoparticles with a complex nanostructured composition, as shown by transmission electron microscopy. Drug release from ibuprofen-cetylpyridinium-alginate nanoparticles was not hindered by alginate, and was similar to the release kinetics from ibuprofen-CPC solubilisates. These innovative carriers developed as polyelectrolyte-surfactant complexes can be used for solubilisation of poorly soluble drugs, where the surfactant simultaneously increases the solubility of the drug at concentrations below its critical micellar concentration and crosslinks the polyelectrolyte to form nanoparticles.
Assuntos
Alginatos/metabolismo , Cetilpiridínio/metabolismo , Ibuprofeno/metabolismo , Nanopartículas/metabolismo , Polieletrólitos/metabolismo , Tensoativos/metabolismo , Alginatos/administração & dosagem , Alginatos/química , Cetilpiridínio/administração & dosagem , Cetilpiridínio/química , Sistemas de Liberação de Medicamentos/métodos , Liberação Controlada de Fármacos , Ibuprofeno/administração & dosagem , Ibuprofeno/química , Nanopartículas/administração & dosagem , Nanopartículas/química , Polieletrólitos/administração & dosagem , Polieletrólitos/química , Espalhamento a Baixo Ângulo , Solubilidade , Tensoativos/administração & dosagem , Tensoativos/química , TermodinâmicaRESUMO
Polycation and peptide-modified surfaces represent opportunities for developing potentially novel biocidal materials in a growing effort to combat bacterial resistance to traditional bactericides. It is well-known that the positive charge of these compounds is crucial to their function in biofouling prevention and as antimicrobials; however, methods for quantifying the number of positive charges on surface-bound polycations and peptides are necessary to predict, control, and optimize the design and therefore the utility of these compounds. This Spotlight on Applications reports on such an approach that combines second harmonic generation (SHG) spectroscopy, quartz crystal microbalance with dissipation monitoring (QCM-D), and atomistic simulations to obtain mechanistic insight into polycation-membrane interactions using supported lipid bilayers (SLBs) as our model system. We find that at high surface coverage, the large polycations we surveyed feature a considerably smaller percentage of ionization when compared to the smaller polycations and peptides. At these high charge densities, we suspect a pKa shift of the charged groups to lower charge-charge repulsion as well as the formation of a looplike conformation such that less monomeric units form contact-ion pairs with the bilayer. Our sum frequency generation (SFG) spectroscopy results complement our understanding of the polycation-membrane interaction. At a high density of the polycation poly(allylamine hydrochloride) (PAH), second-order spectral line shapes are consistent with the expulsion of interfacial water molecules possibly due to contact-ion pair formation between PAH and the lipid bilayer. This finding could be essential for understanding the underlying first steps of cell lysis and penetration by polycations and should be explored further.