Immunoliposomes and PEGylated Immunoliposomes: Possible Use for Targeted Delivery of Imaging Agents

Liposomes can be made target-specific by immobilizing antibodies on their surface against characteristic components of target organ or tissue. Possible schemes of antibody immobilization on liposomes are briefly considered. The use of immunoliposomes for the targeted delivery of diagnostic and therapeutic agents within the cardiovascular system is discussed. Immunoliposomes are shown to be suitable carriers for targeting blood vessel injuries, lung endothelium, and myocardial infarction. The role of polyethylene glycol in the preparation of long-circulation liposomes is investigated, and a hypothesis explaining the mechanism of polymer protective action in terms of physicochemical properties of diluted polymeric solutions is suggested. Polyethylene glycol-coated liposomes are investigated as possible carriers of imaging agents for gamma and MR visualization of different areas of interest in the body, including lymph nodes. The possibility of simultaneous immobilization of protective polymer and antibody on the liposome surface is proved, and the long-circulating targeted immunoliposomes are used for the targeted delivery of radiolabel to necrotic areas in rabbits with experimental myocardial infarction.     

PEGylated Single-Walled Carbon Nanotubes as Nanocarriers for Cyclosporin A Delivery

Single-walled carbon nanotubes (SWCNTs) have attracted the attention of many researchers due to their remarkable physicochemical features and have been found to be a new family of nanovectors for the delivery of therapeutic molecules. The ability of these nanostructures to load large amounts of drug molecules on their outer surface has been considered as the main advantage by many investigators. Here, we report the development of a PEGylated SWCNT-mediated delivery system for cyclosporin A (CsA) as a potent immunosuppressive agent. The available OH group in the CsA structure was first linked to a bi-functional linker (i.e., succinic anhydride) in order to provide a COOH terminal group. CsA succinylation process was optimized by using the modified simplex method. The resulting compound, CsA–CO–(CH₂)₂–COOH, was then grafted onto the exterior surface of SWCNTs, previously PEGylated with phospholipid–PEG₅₀₀₀–NH₂ conjugates, through the formation of an amide bond with the free amine group of PEGylated SWCNTs. Drug loading, stability of the PEGylated SWCNT–CsA complex, and in vitro release of the drug were evaluated. Loading efficiencies of almost 72% and 68% were achieved by UV spectrophotometry and elemental analysis methods, respectively. It was observed that 57.3% of cyclosporine was released from CsA–Pl–PEG₅₀₀₀–SWCNTs after 3 days. In this investigation, we conjugated CsA to an amine-terminated phospholipid–polyethylene glycol chain attached on SWCNTs via a cleavable ester bond and demonstrated the possible potential of PEGylated SWCNT-based systems for CsA delivery.     

Synthetic Antimicrobial Peptides: I. Antimicrobial Activity of Amphiphilic and Nonamphiphilic Cationic Peptides

Comparative antimicrobial properties of three artificial cationic synthetic antimicrobial peptides (SAMP): (RAhaR)₄AhaβA (where R is Arg, Aha is 6-aminohexanoic acid, βA is beta-alanine), (KFF)₃K and R₉F₂ with various amphiphilic properties have been studied relative to pathogenic strains of microorganisms: Gram-negative bacteria Pseudomonas aeruginosa, Escherichia coli, Proteus mirabilis, and Salmonella enterica, Gram-positive bacteria Staphylococcus aureus, and pathogenic yeast fungus Candida albicans. The selectivity index (SI) values of the peptide preparations were calculated as the ratio of the 50% cytotoxic concentration (TC₅₀) towards eukaryotic host cells to the MIC₅₀ values of the testing antimicrobial peptides. The studied SAMPs appeared to be the most active against the pathogenic yeast fungus C. albicans and the bacterial strains St. aureus and P. aeruginosa. The SI values in these cases exceed 40. Some assumed molecular interactions of the studied SAMPs on the microbial cells have been considered, and possible pathways to increase their antimicrobial activity have been suggested. The proposed SAMPs can serve as a basis for the design and synthesis of new promising synthetic antimicrobial agents.     

Preparation of Cationic Immunovesicles Containing Cationic Peptide Lipid for Specific Drug Delivery to Target Cells

The cationic vesicle composed of Span80 and cationic peptide lipid (CPL) was prepared. The cytotoxicity of the Span80-CPL cationic vesicle was very low compared with Span80 vesicle. Antibody was able to be immobilized on vesicle surface by mediation of protein A. The antigen targeting ability of the antibody-immobilized vesicle (immunovesicle) derived from antibody was evaluated. Our results suggested that the Span80-CPL immunovesicles specifically associate with target cells by the antibody mediation, and the substance capsulated in immunovesicle was transferred into the target cells. This means that the Span80-CPL immunovesicle is expected to achieve a high local concentration of an encapsulated drug at the target.     

Cationic Glycosphingolipids in Neuronal Tissues and Their Possible Biological Significance

During the course of studies on natural occurrence of sphingosine base in brain, cationic glycosphingolipids bound to carboxymethyl-Sephadex and eluted with triethylamine in organic solvents were isolated and characterized. Four classes of compounds were identified: (i) plasmalopsychosine-A and -B; (ii) glyceroplasmalopsychosine; (iii) glycosphingolipids having de-N-acetyl-hexosamine, e.g., de-N-acetyl-Lc₃Cer; (iv) glycosylsphingosine, i.e., lysoglycosphingolipid. Only two kinds, galactosylsphingosine (psychosine) and lactosylsphingosine, were found to occur naturally in brain. All these compounds were isolated from extract of brain white matter. Their occurrence, quantity, and distribution pattern differ from one species to another. Their quantity is much lower than that of regular acidic and neutral glycosphingolipids. They may interact with regular glycosphingolipids in glycosphingolipid-enriched microdomains to elicit signal transduction, to modify cellular phenotype, although studies along this line are highly limited at this time.     

Amphiphilic triblock copolymers with PEGylated hydrocarbon structures as environmentally friendly marine antifouling and fouling-release coatings

The ideal marine antifouling (AF)/fouling-release (FR) coating should be non-toxic, while effectively either resisting the attachment of marine organisms (AF) or significantly reducing their strength of attachment (FR). Many recent studies have shown that amphiphilic polymeric materials provide a promising solution to producing such coatings due to their surface dual functionality. In this work, poly(ethylene glycol) (PEG) of different molecular weights (M_w?=?350, 550) was coupled to a saturated difunctional alkyl alcohol to generate amphiphilic surfactants (PEG-hydrocarbon-OH). The resulting macromolecules were then used as side chains to covalently modify a pre-synthesized PS₈?_K-b-P(E/B)₂₅?_K-b-PI₁₀?_K (SEBI or K3) triblock copolymer, and the final polymers were applied to glass substrata through an established multilayer surface coating technique to prepare fouling resistant coatings. The coated surfaces were characterized with AFM, XPS and NEXAFS, and evaluated in laboratory assays with two important fouling algae, Ulva linza (a green macroalga) and Navicula incerta, a biofilm-forming diatom. The results suggest that these polymer-coated surfaces undergo surface reconstruction upon changing the contact medium (polymer/air vs polymer/water), due to the preferential interfacial aggregation of the PEG segment on the surface in water. The amphiphilic polymer-coated surfaces showed promising results as both AF and FR coatings. The sample with longer PEG chain lengths (M_w?=?550?g?mol^?1) exhibited excellent properties against both algae, highlighting the importance of the chemical structures on ultimate biological performance. Besides reporting synthesis and characterization of this new type of amphiphilic surface material, this work also provides insight into the nature of PEG/hydrocarbon amphiphilic coatings, and this understanding may help in the design of future generations of fluorine-free, environmentally friendly AF/FR polymeric coatings.     

Uncharged Gemini-Amphiphiles as Components of Cationic Liposomes for Delivery of Nucleic Acids

Russian Journal of Bioorganic Chemistry - New uncharged gemini-amphiphiles have been synthesized. A series of cationic liposomes based on the polycationic amphiphile...     

Combining Cationic Liposomal Delivery with MPL-TDM for Cysteine Protease Cocktail Vaccination against Leishmania donovani : Evidence for Antigen Synergy and Protection

BackgroundWith the paucity of new drugs and HIV co-infection, vaccination remains an unmet research priority to combat visceral leishmaniasis (VL) requiring strong cellular immunity. Protein vaccination often suffers from low immunogenicity and poor generation of memory T cells for long-lasting protection. Cysteine proteases (CPs) are immunogenic proteins and key mediators of cellular functions in Leishmania. Here, we evaluated the vaccine efficacies of CPs against VL, using cationic liposomes with Toll like receptor agonists for stimulating host immunity against L. donovani in a hamster model.Conclusion/SignificanceThe present study is the first report of a comparative efficacy of leishmanial CPs and their cocktail using liposomal formulation with MPL-TDM against L. donovani. The level of protection attained has not been reported for any other subcutaneous single or polyprotein vaccination against VL.     

Synthesis of Fluorescent Cationic Lipids for Evaluation of Cellular Pathways and Delivery Mechanisms of Antisense Oligonucleotides

Abstract

The synthesis of BODIPY conjugated cationic lipids was achieved in three steps from 3-bromopropane-1,2 diol as the starting material. These compounds were evaluated for their ability to enhance cellular uptake of the antisense oligonucleotides.     

Optimization of the Technology for the Preparation of Cationic Liposomes for the Delivery of Nucleic Acids

Russian Journal of Bioorganic Chemistry - Cationic liposomes based on the cationic lipid 1,26-bis(cholest-5-en-3β-yloxycarbonylamino)- 7,11,16-2-tetraazahexacosane tetrahydrochloride (2X3) and...     

Enhanced Gene Delivery and Expression in Human Hepatocellular Carcinoma Cells by Cationic Immunoliposomes

Abstract

A targeted vector allowing enhanced gene transfer to human hepatocellular carcinoma (HCC¹) cells in vitro was developed using cationic liposomes covalently conjugated with the mAb AF-20. This high affinity antibody recognizes a rapidly internalized 180 kDa cell surface glycoprotein which is abundantly expressed on the surface of human HCC and other cancer cells. Quantitative binding analysis of liposomes with target cells by flow cytometry showed specific association of mAb-targeted liposomes with human HCC cells. Using mAb-targeted cationic liposomes containing 20% DOTAP, in the presence or absence of serum, gene expression in HuH-7 cells was enhanced up to 40-fold as compared to liposomes conjugated with an isotype-matched non-relevant control antibody. Transfection specificity was not observed in a control cell line that does not express the antigen recognized by mAb AF-20. This study demonstrates that cationic liposome formulations can be targeted with monoclonal antibodies (mAbs) to enhance specific in vitro gene delivery and expression in the presence or absence of serum.     

Cyclodextrins and their uses: a review

Cyclodextrins are a family of cyclic oligosaccharides composed of α-(1,4) linked glucopyranose subunits. Cyclodextrins are useful molecular chelating agents. They possess a cage-like supramolecular structure, which is the same as the structures formed from cryptands, calixarenes, cyclophanes, spherands and crown ethers. These compounds having supramolecular structures carry out chemical reactions that involve intramolecular interactions where covalent bonds are not formed between interacting molecules, ions or radicals. The majority of all these reactions are of ‘host–guest’ type. Compared to all the supramolecular hosts mentioned above, cyclodextrins are most important. Because of their inclusion complex forming capability, the properties of the materials with which they complex can be modified significantly. As a result of molecular complexation phenomena CDs are widely used in many industrial products, technologies and analytical methods. The negligible cytotoxic effects of CDs are an important attribute in applications such as rug carrier, food and flavours, cosmetics, packing, textiles, separation processes, environment protection, fermentation and catalysis.     

PEGylated protein separations: challenges and opportunities

PEGylation, the covalent attachment of polyethylene glycol (PEG) chains to protein, isa promising method for making an efficient protein drug. Several PEGylated protein drugs, such as PEGylated interferons, are already on the market and others are presently in their clinical trials. However, the PEGylation reaction is very product specific so that generalized or platform processes for both reaction and purification have not yet been established. In the current issue of Biotechnology Journal, Günter Allmaier and colleagues report a modified microchip capillary gel electrophoresis (MCGE), which allows for a rapid separation (one minute) of PEGylated proteins of different degrees of PEGylation.     

新一代植物志:机遇与挑战

植物多样性是地球生态系统和人类赖以生存的基础,植物资源是我国经济社会可持续发展不可或缺的条件。植物志(Flora)是植物多样性保护和可持续利用最为基础的植物典籍,它为物种的准确鉴定提供了必要的前提和保证,为合理利用植物资源提供了重要的信息和科学依据,在服务于我国国民经济和社会发展,提高公众对生物多样性的认识等方面发挥着重要作用。     

Delivery of Brain-Derived Neurotrophic Factor by 3D Biocompatible Polymeric Scaffolds for Neural Tissue Engineering and Neuronal Regeneration

Biopolymers are increasingly employed for neuroscience applications as scaffolds to drive and promote neural regrowth, thanks to their ability to mediate the upload and subsequent release of active molecules and drugs. Synthetic degradable polymers are characterized by different responses ranging from tunable distension or shrinkage to total dissolution, depending on the function they are designed for. In this paper we present a biocompatible microfabricated poly-ε-caprolactone (PCL) scaffold for primary neuron growth and maturation that has been optimized for the in vitro controlled release of brain-derived neurotrophic factor (BDNF). We demonstrate that the designed morphology confers to these devices an enhanced drug delivery capability with respect to monolithic unstructured supports. After incubation with BDNF, micropillared PCL devices progressively release the neurotrophin over 21 days in vitro. Moreover, the bioactivity of released BDNF is confirmed using primary neuronal cultures, where it mediates a consistent activation of BDNF signaling cascades, increased synaptic density, and neuronal survival. These results provide the proof-of-principle on the fabrication process of micropatterned PCL devices, which represent a promising therapeutic option to enhance neuronal regeneration after lesion and for neural tissue engineering and prosthetics.     

Effective Viral Delivery of Genetic Constructs to Neuronal Culture for Modeling and Gene Therapy of GNAO1 Encephalopathy

Molecular Biology - GNAO1 encephalopathy is an orphan genetic disease associated with early infantile epilepsy, impaired motor control, and severe developmental delay. The disorder is caused by...     

用作基因传递系统的阳离子纳米载体的 细胞毒性及其机制研究进展

作为基因治疗中的非病毒基因载体,阳离子纳米载体可通过电荷作用与核酸类药物相结合,具有广阔的应用前景。然而,其细胞毒 性,主要表现为诱导细胞凋亡,限制了其临床开发与应用,也成为阳离子纳米载体研究所关注的重点。揭示和准确评价阳离子纳米载体的 细胞毒性及其机制,将有助于设计和开发更安全、更高效地用于基因传递的阳离子纳米载体。综述常用作基因传递系统的阳离子纳米载体 材料阳离子脂质体、聚乙烯亚胺、多聚赖氨酸、聚苯乙烯纳米粒以及其他阳离子聚合物的细胞毒性及其机制研究进展。