Self-assembly Of Conjugates Research Articles

Drug Delivery Vehicles Based on Albumin-Polymer Conjugates.

Albumin has been a popular building block to create nanoparticles for drug delivery purposes. The performance of albumin as a drug carrier can be enhanced by combining protein with polymers, which allows the design of carriers to encompass a broader spectrum of drugs while features unique to synthetic polymers such as stimuli-responsiveness are introduced. Nanoparticles based on polymer-albumin hybrids can be divided into two classes: one that carries album as a bioactive surface coating and the other that uses albumin as biocompatible, although nonbioactive, building block. Nanoparticles with bioactive albumin surface coating can either be prepared by self-assembly of albumin-polymer conjugates or by postcoating of existing nanoparticles with albumin. Albumin has also been used as building block, either in its native or denatured form. Existing albumin nanoparticles are coated with polymers, which can influence the degradation of albumin or impact on the drug release. Finally, an alternative way of using albumin by denaturing the protein to generate a highly functional chain, which can be modified with polymer, has been presented. These albumin nanoparticles are designed to be extremely versatile so that they can deliver a wide variety of drugs, including traditional hydrophobic drugs, metal-based drugs and even therapeutic proteins and siRNA.

Preparation of Biocatalytic Microparticles by Interfacial Self-Assembly of Enzyme-Nanoparticle Conjugates Around a Cross-Linkable Core.

Rational design of hierarchical interfacial assembly of reusable biocatalytic microparticles is described in this chapter. Specifically, purified enzymes and functionalized nanoparticles are electrostatically assembled at the interface of cross-linked microparticles which are formed through ring opening metathesis polymerization. The diameters of microparticle assemblies average 10μm, and they show enhanced kinetic efficiency as well as improved stability against heat, pH, and solvent denaturation when compared to stabilities of the corresponding native enzymes.

Amino Acid Chirality and Ferrocene Conformation Guided Self-Assembly and Gelation of Ferrocene-Peptide Conjugates.

The self-assembly and gelation behavior of a series of mono- and disubstituted ferrocene (Fc)-peptide conjugates as a function of ferrocene conformation and amino acid chirality are described. The results reveal that ferrocene-peptide conjugates self-assemble into organogels by controlling the conformation of the central ferrocene core, through inter- versus intramolecular hydrogen bonding in the attached peptide chain(s). The chirality controlled assembling studies showed that two monosubstituted Fc conjugates FcCO-LFLFLA-OMe and FcCO-LFLFDA-OMe form gels with nanofibrillar network structures, whereas the other two diastereomers FcCO-DFLFLA-OMe and FcCO-LFDFLA-OMe exclusively produced straight nanorods and non-interconnected small fibers, respectively. This suggests the potential tuning of gelation behavior and nanoscale morphology by altering the chirality of constituted amino acids. The current study confirms the profound effect of diastereomerism and no influence of enantiomers on gelation. Correspondingly, the diastereomeric and enantiomeric Fc[CO-FFA-OMe]2 were constructed for the study of chirality-organized structures.

Multiplex ELISA Using Oligonucleotide Tethered Antibodies.

Multiplex assays represent a new paradigm for diagnostics. The simultaneous measure of multiple analytes from a single sample is advantageous in creating disease-associated panels that enable more accurate prognosis or diagnosis of the disease state. Furthermore, multiplexing may reduce reagent consumption, sample requirements and labor thereby lowering the cost per test. Here we describe a novel multiplex immunoassay technology based upon creating microarrays in microtiter plates that are formed upon the self-assembly of oligonucleotide-antibody conjugates.

Tumor-specific delivery of siRNA using supramolecular assembly of hyaluronic acid nanoparticles and 2b RNA-binding protein/siRNA complexes

Anticancer therapeutics delivering exogenous siRNA have been explored to suppress the tumor-associated genes, but several limitations of siRNA delivery such as tumor-targeted delivery, controlled siRNA release at the sites of interest, or instabilities of siRNA in physiological fluids should be preferentially addressed for its clinical applications. As an attempt to meet these criteria, we designed a supramolecular assembly, which was composed of cholesterol-bearing hyaluronic acid (HA-Chol) conjugates and 2b RNA-binding protein (2b)/siRNA complexes. In contrast to the traditional siRNA polyplexes using electrostatic interactions, HA-Chol nanoparticles, as a results of self-assembly of HA-Chol conjugates, provide the hydrophobic core that acts as the container for 2b protein/siRNA complexes, where a high affinity of 2b protein for siRNA could neutralize the negative-charged siRNA. Here, we investigated the potential of HA-Chol/2b/siRNA complexes as the siRNA carriers that provide encapsulation, protection, and targeted delivery of siRNA. The HA-Chol nanoparticles could selectively deliver 2b protein/siRNA complexes to the tumor cells with up-regulated CD44 receptors and suppress the expression of target gene. The pH-associated binding properties of siRNA for 2b proteins allowed the controlled release of siRNA in the endocytic compartments, and ultimately the released siRNA could obtain the RNAi acitivities in the cells, whereas the encapsulated 2b proteins still stayed within the HA-Chol nanoparticles. Our delivery systems demonstrate the promising potential of the efficient siRNA carriers in the anticancer therapeutic applications.

Porphysome nanoparticles: Tailoring treatments with nature’s pigments

AbstractPorphysomes are an emerging class of photonic nanoparticles formed from the self-assembly of porphyrin-lipid conjugates. They retain the multifunctional properties of their porphyrin building-blocks but also have unique properties emerging from the nanostructure itself. Porphysomes are able to act in a number of photonic modalities, from diagnostic fluorescence and photoacoustic imaging, to photodynamic and photothermal therapies. This flexibility enables customizable interventions with potential in the burgeoning field of personalized medicine. Here, we profile early porphysome-like liposomes, true porphysomes, as well as newer porphysome derivatives. We discuss the current applications and future outlook for these multimodal theranostic nanoparticles.

Supramolecular control of self-assembling terthiophene–peptide conjugates through the amino acid side chain

The self-assembly of oligothiophene-peptide conjugates can be directed through the systematic variation of the peptide sequence into different nanostructures, including flat spicules, nanotubes, spiral sheets, and giant, flat sheets. Furthermore, the assembly of these molecules is not controlled by steric interactions between the amino acid side chains.

Addressable Microfluidic Polymer Chip for DNA‐Directed Immobilization of Oligonucleotide‐Tagged Compounds

A microfluidic polymer chip for the self-assembly of DNA conjugates through DNA-directed immobilization is developed. The chip is fabricated from two parts, one of which contains a microfluidic channel produced from poly(dimethylsiloxane) (PDMS) by replica-casting technique using a mold prepared by photolithographic techniques. The microfluidic part is sealed by covalent bonding with a chemically activated glass slide containing a DNA oligonucleotide microarray. The dimension of the PDMS-glass microfluidic chip is equivalent to standard microscope slides (76 x 26 mm(2)). The DNA microarray surface inside the microfluidic channels is configured through conventional spotting, and the resulting DNA patches can be conveniently addressed with compounds containing complementary DNA tags. To demonstrate the utility of the addressable surface within the microfluidic channel, DNA-directed immobilization (DDI) of DNA-modified gold nanoparticles (AuNPs) and DNA-conjugates of the enzymes glucose oxidase (GOx) and horseradish peroxidase (HRP) are carried out. DDI of AuNPs is used to demonstrate site selectivity and reversibility of the surface-modification process. In the case of the DNA-enzyme conjugates, the patterned assembly of the two enzymes allows the establishment and investigation of the coupled reaction of GOx and HRP, with particular emphasis on surface coverage and lateral flow rates. The results demonstrate that this addressable chip is well suited for the generation of fluidically coupled multi-enzyme microreactors.

Self-Assembly of [60]Fullerene−Thiol Derivatives on Mercury Surfaces

Herein we report the first self-assembly of fullerene-thiol conjugates (1 and 2) on thin mercury films (TMF) deposited on a glassy carbon electrode (GCE). The fullerene-containing SAMs were investigated by cyclic voltammetry and water contact angle measurements. Two reversible, surface-confined redox couples were obtained for the fullerene-containing SAMs on TMF/GCE in CH(2)Cl(2) solution. The surface coverage of both fullerene derivatives 1 and 2 on TMF/GCE was measured to be in the range of (1.7-1.8) x 10(-10) mol cm(-2). Both SAMs of 1 and 2 partially blocked the electron transfer across the electrode in aqueous solution. The contact angle measurements performed on TMFs clearly showed an enhancement of the surface hydrophobicity upon formation of the fullerene-containing monolayer.

Synthesis and self-assembly of perylenediimide-oligonucleotide conjugates.

Synthesis and self-assembly of perylenediimide-oligonucleotide conjugates.

Self-assembly of polyoxometalate conjugates: novel models for catalytic surfaces from crystal data

Self-assembly of new organic conjugates of the pentamolybdodiphosphonato cage with cyclic aminomethylphosphonates has been achieved. The crystal structures of two of the conjugates have been determined and all of them characterised by IR spectroscopy. Intramolecular hydrogen bonding of the aminomethyl moiety to cage oxygen and close intermolecular C–H ⋯ O–Mo contacts (between 2.3 and 2.5 A for the H ⋯ O distance) are observed, providing a new model for the interaction of substrates with a polyoxometalate catalytic surface. A scheme for modelling the pentamolybdodiphosphonato cage with a distance-restraint-based model is presented.