Oligo Ethylene Glycol Moieties Research Articles

Pd(II)dipyrrinato complexes: Synthesis, crystal structure and their antibacterial applications

The synthesis and biological studies of a series of Pd(II)dipyrrinato complexes are reported. The thiogalactosyl and/or oligoethyleneglycol moieties were linked with themeso-aryl rings of the Pd(II)dipyrrinato complexes. The Pd(II)dipyrrinato complexes were characterized by MASS, IR, UV-Vis, and NMR spectroscopic techniques. Single crystal X-ray structure of the homoleptic Pd(II)dipyrrinato complex (Pd1) revealed typical square planar geometry around the metal center. The anti-bacterial studies of Pd(II) dipyrrinato complexes were performed on theM. Tuberculosis H37Rv and M. Bovis BCG strains and complex Pd4 showed excellent anti-TB activity with MIC values of 25 [Formula: see text]M and 12.5 [Formula: see text]M, respectively. The ease of synthesis and good MIC values of Pd(II)dipyrrinato complexes make them promising candidates for anti-TB activity.

Fabrication of Biosensing Interface with Monolayers.

Surface modification is recognized as one of the fundamental techniques to fabricate biosensing interfaces. This review focuses on the surface modification of carbon substrates (GC and HOPG) and silica with a close-packed monolayer, in particular. In the cases of carbon substrates, GC and HOPG, it was demonstrated that surface modification of carbon substrates with diazonium derivatives could create a close-packed monolayer similar to the self-assembled monolayer (SAM) formation with mercapto derivatives. Similarly, the potential of trialkoxysilanes to form a close-packed monolayer was evaluated, and modification with a close-packed monolayer tended to occur under milder conditions when the trialkoxysilanes had a longer alkyl chain. In these studies, we synthesized surface modification materials having ferrocene as a redox active moiety to explore features of the modified surfaces by an electrochemical method using cyclic voltammetry, where surface concentrations of immobilized molecules and blocking effect were studied to obtain insight for density leading to a close-packed layer. Based on those findings, fabrication of a biosensing interface on the silica sensing chip of the waveguide-mode sensor was carried out using triethoxysilane derivatives bearing succinimide ester and oligoethylene glycol moieties to immobilize antibodies and to suppress nonspecific adsorption of proteins, respectively. The results demonstrate that the waveguide-mode sensor powered by the biosensing interface fabricated with those triethoxysilane derivatives and antibody has the potential to detect several tens ng/mL of biomarkers in human serum with unlabeled detection method.

Interfacial Structure and Function of Nano-Structured Membranes of Newly Synthesized Phosphorylcholine Derivatives on Single Crystal Electrodes

Properties of modified surface for biosensing interface are recognized as important subjects to develop methodologies in bio-related analysis and techniques. Therefore, various surface modification materials to fabricate biosensing interface have been synthesized and studied on properties of modified surface of gold,1-4 carbon,5 silicon6 and some polymer7,8 substrates for application to biosensor and micro flow analytical system. The non-specific adsorption of proteins that occurs during analysis of biomolecules often has a serious detrimental effect on selectivity and detection limit, and research on surface modification materials has attracted great interest with a view to avoiding the interference caused by the non-specific adsorption of proteins. The properties of polyethylene glycol (PEG) such as flexibility, chemical stability, water solubility, and low cytotoxicity make it a versatile surface modification material. The most attractive property of PEG is its suppressive effect on the non-specific adsorption of proteins. While polymers consisting of the ethylene glycol moiety have been studied extensively, it has also been reported that self-assembled monolayers (SAMs) of oligoethylene glycol-alkane thiols suppress the non-specific adsorption of proteins in a similar way to surfaces modified with PEG. Our previous work showed that SAMs of oligoethylene glycol–alkane thiols effectively suppressed the non-specific adsorption of proteins allowing us to realize the high performance detection of proteins.1 On the other hand, phosphorylcholine derivatives are other promising candidates for suppressing the non-specific adsorption of proteins because the phosphorylcholine group is one of the primary lipid components of plasma membranes. Although SAMs of phosphorylcholine-alkane thiols were also reported to suppress the non-specific adsorption of proteins, there have been relatively few studies related to SAMs of phosphorylcholine-alkane thiols compared with those on SAMs of oligoethylene glycol–alkane thiols. Therefore, we are interested in the properties of phosphorylcholine SAMs. It was found that newly synthesized phosphorylcholine-alkane thiols bearing the oligoethylene glycol moiety, namely phosphorylcholine–oligoethylene glycol–alkane thiols, formed SAMs on gold surfaces and suppressed fibrinogen adsorption more effectively than the corresponding oligoethylene glycol–alkane thiols.2 The incorporation of oligoethylene glycol moieties in phosphorylcholine-alkane thiols enhanced the suppressive effect on concanavalin A adsorption but not on fibrinogen adsorption. Furthermore, we studied the newly synthesized zwitterion–alkane thiol SAMs which have phosphorylcholine, inverse phosphorylcholine and sulfobetaine terminal groups as shown in Figure 1, and repot here mainly the results on the interfacial structure and function of the phosphorylcholine-alkane thiol SAMs on a single crystal Au(111) electrode in solution. An electrochemical scanning tunneling microscope (EC-STM) was used to observe surface feature of phosphorylcholine-dodecanethiol (C12PC) SAMs on Au(111) in 0.1M HClO4, and mostly flat terrace surface with the surface roughness less than 0.3 nm was observed in a wide scan area, indicating that the molecules were closely packed. A typical high-resolution EC-STM images of C12PC SAM on Au(111) was presented in Figure 2. Bright spots aligned toward √3 directions were clearly observed with spacing of 0.5 nm, corresponding to individual C12PC molecules. The molecular arrangement was assigned to (√3 x 3√3)R30° structure with two C12PC molecules in the lattice. The surface coverage of the monolayer was 2/9, which is consistent with that from the charge of electrochemical reductive desorption process with an assumption of one-electron reaction. In the case of the phosphorylcholine–diethylene glycol–alkane thiols (C12O2PC) SAMs, the monolayer exhibited the double-striped (√3 x 3√3)R30° structure with a molecular coverage of 2/9, where every three C12O2PC molecular rows was missing. In comparison with C12PC and C12O2PC SAMs, the molecular arrangement of C12PC would be (√3 x 3√3)R30°-2C12PC missing row structure, which is the same as that of the C12O2PC SAM, because of bulkiness of phosphorylcholine head group. A detailed analysis of the surface structure will be discussed with the function suppressing the non-specific adsorption of proteins.References(1) Y. Sato, K. Yoshioka, M. Tanaka, T. Murakami, M. N.Ishida, N. Niwa, Chem. Commun., 4909 (2008).(2) M. Tanaka, T. Sawaguchi, Y. Sato, K. Yoshioka, O. Niwa, Tetrahedron Lett., 50, 4092 (2009).(3) S. Taira, D. Kaneko, K. Yokoyama, T. Sawaguchi, J. Molecular Imaging & Dynamics, S1-001, 1 (2012).(4) M. Tanaka, T. Sawaguchi, Y. Hirata, O. Niwa, K. Tawa, C. Sasakawa, K. Kuraoka, J. Colloid and Interface Sci., 497, 309 (2017).(5) M. Tanaka, T. Sawaguchi, Y. Sato, K. Yoshioka, O. Niwa, Langmuir, 27, 170 (2011).(6) M. Tanaka, T. Sawaguchi, M. Kuwahara, O. Niwa, Langmuir, 29, 6361 (2013).(7) M. Tanaka, Y. Hirata, T. Sawaguchi, S. Kurosawa, Arkivoc, ii, 330 (2018).(8) M. Tanaka, Y. Ogawa, Y. Hirata Y, T. Sawaguchi, S. Kurosawa, Sensors and Materials, 31, 33 (2019). Figure 1

Unraveling the role of β1 integrin isoforms in cRGD-mediated uptake of nanoparticles bearing hydrophilized alkyne moieties in epithelial and endothelial cells

The uptake and trafficking of NPs is impacted by several attributes such as size, shape, surface charge and importantly by surface ligands that can interact with the cell plasma membrane. We envision that NPs which can be readily modified in aqueous environments will be key to engineering patient-specific nanotherapeutics. Towards such systems that can be functionalized “on demand” in aqueous environments, an α−ω epoxy ester monomer that bears an alkyne group at the end of an oligoethylene glycol moiety was designed and synthesized. Copolymerization of this monomer with ε-caprolactone yielded polymers that present hydrophilized alkyne groups along the backbone. This enabled the direct modification of the surface of NPs, as suspensions in aqueous phase, with cell interaction peptides such cyclic-arginine-glycine-aspartic acid (cRGD) using the “click reaction”. Uptake of cRGD modified NPs (cRGD-NPs) in human endothelial and tumor epithelial cells revealed that cRGD surprisingly diminished uptake in both tumor epithelial and microvascular endothelial cells by 40–50 percent in comparison to unmodified particles. Probing the mechanism of uptake revealed that the expression pattern of two isoforms of β1 integrin impacted the uptake of cRGD-NPs differently. While the expression of high molecular weight 140 kDa form of the β1 integrin enhanced NP uptake, the expression of low molecular 120 kDa form had an inhibitory effect. Furthermore, although, the expression of β3 integrin was enhanced in endothelial cells and breast cancer epithelial cells, no correlation between β3 integrin and NP uptake was observed. Additionally, in presence of clathrin and caveolae pathway inhibitors the uptake of cRGD-NPS was in general diminished with a 25–75% decrease in presence of Filipin, a caveolae inhibitor; suggesting a role for lipid rafts in the β1 integrin-mediated uptake of cRGD-NP NPs. In sum, the polymer system described can be readily adapted to engineer other targeting peptide-based nanotherapeutics, especially for the delivery across difficult penetrate biological barriers such as the blood brain barrier. The main findings of this study have significant implication for the development of integrin targeted nanotherapeutics for anti-tumor therapy.

A New Family of Thermo-, pH-, and CO2-Responsive Homopolymers of Poly[Oligo(ethylene glycol) (N-dialkylamino) methacrylate

A new family of thermo-, pH-, and CO2-responsive homopolymers of poly[oligo(ethylene glycol)(N-dialkylamino)methacrylate]s combining the pendants of oligo ethylene glycol (OEG) moiety and dialkylamine are synthesized by RAFT polymerization. In these poly[oligo(ethylene glycol) (N-dialkylamino) methacrylate]s, the OEG moiety as well as the dialkylamine group affords thermoresponse, and the dialkylamine group affords pH-, and CO2-response. The phase transition temperature (CP) of poly[oligo(ethylene glycol) (N-dialkylamino) methacrylate]s is firmly correlative to the number of the OEG moiety and the dialkylamine group, and it is found that higher number of the OEG moiety and higher CP, and the longer dialkylamine group and the lower CP, respectively. By tuning the OEG moiety and the dialkylamine group, eight thermo-, pH-, and CO2-responsive homopolymers with CPs ranging from 7 to 79 °C are synthesized. The thermoresponsive phase transition of poly[oligo(ethylene glycol) (N-dialkylamino) methacrylate]s is in...

Entropically Driven Self‐Assembly of Bolaamphiphilic Perylene Dyes in Water

AbstractThe specific hydrophobic effect involved in the self‐assembly of a bolaamphiphilic perylene bisimide (PBI) dye bearing oligoethylene glycol (OEG) chains has been identified. In pure water, the self‐assembly is entropically driven and enthalpically disfavored, as explored by optical spectroscopy and isothermal titration calorimetry studies. Besides strong π–π interactions between the PBI units that are primarily of enthalpic nature, the major contribution to the self‐assembly is the gain of entropy by release of confined water molecules from the hydration shell of the hydrophilic OEG moieties. Both contributions favor self‐assembly, but their countervailing thermodynamic parameters are reflected in an uncommon temperature dependence, which can be inverted upon gradual addition of an organic cosolvent that makes the π–π interaction increasingly dominant.

Entropically Driven Self-Assembly of Bolaamphiphilic Perylene Dyes in Water.

The specific hydrophobic effect involved in the self-assembly of a bolaamphiphilic perylene bisimide (PBI) dye bearing oligoethylene glycol (OEG) chains has been identified. In pure water, the self-assembly is entropically driven and enthalpically disfavored, as explored by optical spectroscopy and isothermal titration calorimetry studies. Besides strong π-π interactions between the PBI units that are primarily of enthalpic nature, the major contribution to the self-assembly is the gain of entropy by release of confined water molecules from the hydration shell of the hydrophilic OEG moieties. Both contributions favor self-assembly, but their countervailing thermodynamic parameters are reflected in an uncommon temperature dependence, which can be inverted upon gradual addition of an organic cosolvent that makes the π-π interaction increasingly dominant.

Water-soluble BODIPY and aza-BODIPY dyes: synthetic progress and applications

In recent years, boron-dipyrromethene (BODIPY) and boron-azadipyrromethene (aza-BODIPY) dyes have attracted considerable multidisciplinary attention due to their diverse applications. By introducing various hydrophilic groups, such as quaternary ammonium, sulfonate or oligo-ethyleneglycol moieties into the BODIPY core, the solubilities of these dyes in aqueous solution can be greatly improved while maintaining their high fluorescence quantum yields. Accordingly, applying these fluorescent dyes in aqueous systems to areas such as chemosensors, biomacromolecule labeling, bio-imaging and photodynamic therapy has been achieved. In this article, the recent progress on the synthesis, optical properties and application of water-soluble BODIPY dyes and aza-BODIPY dyes is reviewed.

Remarkable structure effects on thermoresponsive properties of dendritic macromolecules

Amphiphilic dendritic macromonomers and their corresponding dendronized polymers were synthesized, and their thermoresponsive properties investigated. These dendritic macromolecules are constructed with a second generation lysine-based dendron as the interior (hydrophobic part) and oligoethylene glycol (OEG) linear chains or dendrons (hydrophilic part) covered in their periphery. By changing from OEG linear chains to OEG dendrons, these dendritic macromolecules carry on their periphery different density of OEG moieties, to investigate the structural effects on their thermoresponsiveness. Topology of dendritic macromolecules changes through polymerization, and the fan-shaped dendritic macromonomers transfer into the corresponding cylindrically shaped dendronized polymers. Furthermore, the amphiphilic characteristic of these dendritic entities can be switched due to the thermally-induced dehydration of OEG moieties. It was found that topology, OEG density in the periphery and switchable amphiphilicity of these dendritic macromolecules show significantly effects on their thermoresponsiveness.

Organocatalysis of nucleophilic substitution reactions by the combined effects of two promoters fused in a molecule: oligoethylene glycol substituted imidazolium salts

Oligoethylene glycol substituted imidazolium salts were synthesized as promoters for a range of SN2 reactions, and their efficiency was examined. These tailor-made organic promoters enhanced the nucleophilicity of alkali metal salts significantly through the combined effects of two promoters (oligoethylene glycols and imidazolium salts) in a single molecule. The effects of the oligoethylene glycol side chain length, ionic liquid anions, nucleophiles, and substrates were investigated systematically. [hexaEGmim][OMs] and [dihexaEGim][OMs] showed the highest efficiency for SN2 reactions using alkali metal salts. The role of the terminal hydroxyl groups of the oligoethylene glycol moiety was assessed by examining the relative SN2 yields of chlorination and bromination. The results showed that the hydrogen bonding strength of the hydroxyl groups with the nucleophile is very important. The mechanism for the excellent promotion of SN2 reactions by oligoEGILs was examined by quantum chemical calculations. The results showed that the oxygen atoms in the oligoethylene glycol portion and the ionic liquid anion act on the counter cation K+ or Na+ as a Lewis base, to enhance the reactivity of the metal salts significantly.

Design and Fabrication of Biosensing Interface for Waveguide-Mode Sensor

In order to develop a biosensing system with waveguide-mode sensor, fabrication of a biosensing interface on the silica surface of the sensing chip was carried out using triethoxysilane derivatives with anti-leptin antibody. Triethoxysilane derivatives bearing succinimide ester and oligoethylene glycol moieties were synthesized to immobilize the antibody and to suppress nonspecific adsorption of proteins, respectively. The chip modified with triethoxysilane derivatives bearing oligoethylene glycol moiety suppressed nonspecific adsorption of proteins derived from human serum effectively by rinse with PBS containing surfactant (0.05% Tween 20). On the other hand, it was confirmed that antibody was immobilized on the chip by immersion into antibody solution to show response of antigen-antibody reaction, where the chip was modified with triethoxysilane derivatives bearing succinimide ester moiety. When the interface was fabricated with antibody and a mixture of triethoxysilane derivatives bearing succinimide ester and oligoethylene glycol moieties, the response of antigen-antibody reaction depended on composition of the mixture and enhanced with the increase of ratio for triethoxysilane derivatives bearing succinimide ester moiety reflecting the antibody concentration immobilized on the chip. While introduction of excess triethoxysilane derivatives bearing succinimide ester moiety induced nonspecific adsorption of proteins derived from human serum, the immobilized antibody on the chip kept its activity after 1-month storage in a refrigerator. Taking into consideration those factors, the biosensing interface was fabricated using triethoxysilane derivatives with anti-leptin antibody to examine performance of the waveguide-mode sensor. It was found that the detection limits for human leptin were 50 ng/mL in PBS and 100 ng/mL in human serum. The results demonstrate that the waveguide-mode sensor powered by the biosensing interface fabricated with those triethoxysilane derivatives and antibody has potential to detect several tens of nanograms per milliliter of biomarkers in human serum with an unlabeled detection method.

Dicationic ionic liquids as lubricants

Twelve dicationic ionic liquids have been investigated for their potential inlubricants. The dications selected were synthesized from oligoethylene glycols linking two cationic moieties based on either N-methylimidazolium or N-methylpyrrolidinium at the extremities. As anions, chloride, bis(trifluoromethanesulfonyl)imide (Tf2N), methanesulfonate and butansulfonate were chosen. Thermal stability of the IL has been evaluated by thermogravimetric analysis and differential scanning calorimetry showing good properties up to 150 °C for all IL. SRV tribotests of neat IL using steel–steel contacts with ball-on-disc geometry were performed at 50 °C, 100 °C and 150 °C. Friction and wear were significantly influenced by both anion structure and chain length of the oligoethylene glycol moiety where longer chains yielded better tribological behavior. The tribological behavior improved with a mixture of different types of ILcontaining F, O, S in their anions. A large variation of ionic liquids corrosiveness and corrosion inhibition, respectively, was found attributed to structure variation. A general tendencyof improving the corrosion resistance when increasing the chain length of the neat ILshas been found. In addition to the neat dicationic ionic liquids, mixtures of 1% of the mostinteresting IL in polypropylene glycol base oil have been studied at 100 °C resulting in more favorable tribological properties for ionic liquids with Tf2N anion. X-ray photoelectron spectroscopy analysis showed that the structures with Tf2N anion create a tribofilm of inorganic fluorine that greatly improves the performance of the base oil.

Biodegradable arginine-based poly(ether ester amide)s as a non-viral DNA delivery vector and their structure–function study

The goal of this study is to develop a new family of L-arginine based poly(ether ester amide)s (Arg-PEEAs) as non-viral gene delivery vectors and study their structure–biological function relationships. A series of Arg-PEEAs were synthesized by the solution polycondensation reaction of the p-toluenesulfonic acid salt of L-arginine diester from oligoethylene glycol and di-p-nitrophenyl esters of dicarboxylic acids. The structure–function relationship was systematically studied through both the measurements of the fundamental property of the Arg-PEEA–DNA polyplex, like zeta potential and particle size, and various biological assays, such as gel retardation assay, GFP assay and luciferase assay. The introduction of the flexible oligoethylene glycol moiety into the Arg-PEEA backbone significantly increased the polymer chain flexibility, which helped to improve the transfection efficiency of Arg-PEEAs over rigid Arg-PEAs. The transfection results obtained from luciferase and GFP assays from a wide range of cell lines, primary cells and stem cells showed that some Arg-PEEAs had comparable or better transfection efficiency than the commercial transfection reagent Lipofectamine2000®, but at a much lower cytotoxicity.

Effect of oligoethylene glycol moieties in porous silicon surface functionalisation on protein adsorption and cell attachment

We report on the synthesis of two carboxy-functional alkene compounds as modifiers of porous silicon (pSi) surface chemistry by means of thermal hydrosilylation. Both alkene compounds have hydrophobic, aliphatic carbon segments, with terminal carboxylic acid functionality appended through a thioether linkage. In one of the alkene linkers, we incorporated a short oligoethylene glycol (OEG) moiety to explore its low-fouling properties when attached to porous silicon. We examined surface stability of the surface-modified porous silicon in aqueous milieu. Albumin and fibronectin were adsorbed and, using carbodiimide chemistry, covalently immobilised to linker-modified porous silicon, and the propensity for mammalian cells to attach to these surfaces investigated. Surface chemistry was characterised by infrared spectroscopy and the stability of porous silicon in an aqueous milieu was investigated by interferometric reflectance spectroscopy (IRS). Surfaces functionalised with the alkene linker containing OEG displayed greater resistance to the adsorption of albumin. This linker also facilitated higher levels of covalent protein immobilisation to the functionalised pSi surface. Higher levels of cell attachment were observed on pSi surfaces with fibronectin covalently immobilised onto the OEG linker, than for fibronectin covalently immobilised on the non-OEG linker.

Functionalization of single-walled carbon nanotubes with (R-)oxycarbonyl nitrenes.

Sidewall functionalization of single-walled carbon nanotubes (SWCNTs) via the addition of (R-)oxycarbonyl nitrenes allows for the covalent binding of a variety of different groups such as alkyl chains, aromatic groups, dendrimers, crown ethers, and oligoethylene glycol units. Such additions lead to a considerable increase in the solubility in organic solvents such as 1,1,2,2-tetrachloroethane (TCE), dimethyl sulfoxide (DMSO), and 1,2-dichlorobenzene (ODCB). The highest solubilities of 1.2 mg/mL were found for SWCNT adducts with nitrenes containing crown ether of oligoethylene glycol moieties in DMSO and TCE, respectively. The presence of chelating donor groups within the addends allowed for the complexation of Cu(2+) and Cd(2+). Atomic force microscopy (AFM) and transmission electron microscopy (TEM) revealed that the functionalized tubes form thin bundles with typical diameters of 10 nm. The presence of thin bundles in solution is supported by (1)H NMR spectroscopy. The elemental composition of the functionalized SWCNT was determined by X-ray photoelectron spectroscopy (XPS). The use of Raman and electron absorption spectroscopy (UV/Vis-nIR) showed that the electronic properties of the SWCNTs are mostly retained after functionalization, indicating a low degree of addition within this series of SWCNT derivatives.

Synthesis of macrocyclic bis(phenylbenzoxazole) derivatives via tandem claisen rearrangement and their fluorescence behavior

AbstractNovel macrocyclic bis(phenylbenzoxazole) derivatives were easily synthesized from macrocyclic isobutenyl bis(amide‐ether)s by tandem Claisen rearrangement and subsequent intramolecular cyclization of the amide‐phenol intermediates. The position of substitution of the oligoethylene glycol moiety on the phenylamido groups of the macrocycles did not have a large effect on the yields of the bis(benzoxazole)s for the meta and para derivatives. The fluorescence quantum yields of most of the macrocyclic bis(benzoxa‐zole)s were lower than those of the corresponding nonmacrocyclic bis(benzoxazole) model compounds. The quantum yields of the para‐substituted macrocyclic bis(benzoxazole)s were clearly lower than those of the model compounds and decreased with increasing length of the oligoethylene chain.

Studying how different terminal groups change the motion of H2NSO2C6H4CONH(EG)3R when bound to the active site of human carbonic anhydrase II.

Molecular dynamics simulations have been used to explore the motions of series of ligands containing coupled benzenesulfonamide and oligoethylene glycol moieties (H2NSO2C6H4CONH(CH2-CH2OCH2CH2OCH2CH2)R+; R+ = NH3+, NHCOCH2NH3+, NHCOCH(CH2Ph)NH3+) bound at the active site of human carbonic anhydrase II (HCAII; E.C. 4.2.1.1). These complexes have been examined previously by X-ray crystallography; the locations of the terminal groups of these ligands were not defined in the crystal structures. These stimulations, carried out in the presence of water, provide dynamic information about the motion of the bound ligand that supplements the quasistatic information from crystallography. Our results suggested that the Gly and Phe groups of these ligands interacted weakly with the protein adjacent to the active site. Quantitative estimates of energies of binding did not correlate usefully with observed free energies of binding, but in the absence of information about entropies, it is not possible to tell if the lack of correlation between calculated energies and observed free energies represents inaccuracies in the energies, or a compensation between enthalpies and entropies. When the terminal Phe group was placed near a previously identified hydrophobic patch in the active site (Phe20 and Pro202) the average conformation of the ligand inferred from this simulation was inconsistent with that from the crystal structure; this result illustrates the problems of misleading local minima in these types of simulations.

Syntheses of Novel Galoctosyl Ligands for Liposomes and the Influence of the Spacer on Accumulation in the Rat Liver.

We modified the surface of liposomes with galactosyl ligands. At first we determined whether or not the galactosyl moiety was exposed on the liposomes. We then investigated the effect of the ligands on the hepatic accumulation of liposomes in rats. We introduced an oligoethylene glycol moiety as a spacer. Among the various ligands tested, those with a tri- or tetraethylene glycol moiety as a spacer caused the greatest accumulation of liposomes in the liver. Liposomes bearing ligands with a tri- or tetraethylene glycol moiety as a spacer, were aggregated by Ricinus communis agglutinin. On the other hand, those modified with ligands with a mono- or diethylene glycol spacer did not clearly agglutinate. These results show the importance of a spacer between the homing device and the ligand anchor.

Preparation and catalytic behavior of cation binding polymers with oligoethyleneglycol moieties as pendant groups

Preparation and catalytic behavior of cation binding polymers with oligoethyleneglycol moieties as pendant groups