Functionalized, biocompatible coating for superparamagnetic nanoparticles by controlled polymerization of a thioglycosidic monomer

The Biocompatibility Analysis of Artificial Mucin-Like Glycopolymers

The ocular surface is covered by a tear film consisting of an aqueous/mucin phase and a superficial lipid layer. Mucins, highly O-glycosylated proteins, are responsible for lubrication and ocular surface protection. Due to contact lens wear or eye disorders, lubrication of the ocular surface can be affected. Artificial glycopolymers which mimic natural mucins could be efficient in ophthalmic therapy. Various neutral, positively, and negatively charged mucin-mimicking glycopolymers were synthesized (n = 11), cultured in different concentrations (1%, 0.1%, and 0.01% w/v) with human corneal epithelial cells (HCE), and analyzed by various cytotoxicity/viability, morphology, and immunohistochemistry (IHC) assays. Six of the eleven glycopolymers were selected for further analysis after cytotoxicity/viability assays. We showed that the six selected glycopolymers had no cytotoxic effect on HCE cells in the 0.01% w/v concentration. They did not negatively affect cell viability and displayed both morphology and characteristic markers as untreated control cells. These polymers could be used in the future as mucin-mimicking semi-synthetic materials for lubrication and protection of the ocular surface.

ortho-Substituted Aryldiazonium Design for the Defect Configuration-Controlled Photoluminescent Functionalization of Chiral Single-Walled Carbon Nanotubes

Defect functionalization of single-walled carbon nanotubes (SWCNTs) by chemical modification is a promising strategy for near-infrared photoluminescence (NIR PL) generation at >1000 nm, which has advanced telecom and bio/medical applications. The covalent attachment of molecular reagents generates sp³-carbon defects in the sp²-carbon lattice of SWCNTs with bright red-shifted PL generation. Although the positional difference between proximal sp³-carbon defects, labeled as the defect binding configuration, can dominate NIR PL properties, the defect arrangement chemistry remains unexplored. Here, aryldiazonium reagents with π-conjugated ortho-substituents (phenyl and acetylene groups) were developed to introduce molecular interactions with nanotube sidewalls into the defect-formation chemical reaction. The functionalized chiral SWCNTs selectively emitted single defect PL in the wavelength range of ∼1230-1270 nm for (6,5) tubes, indicating the formation of an atypical binding configuration, different from those exhibited by typical aryl- or alkyl-functionalized chiral tubes emitting ∼1150 nm PL. Moreover, the acetylene-based substituent design enabled PL brightening and a subsequent molecular modification of the doped sites using click chemistry.

Tailor-made Glycopolymers via Reversible Deactivation Radical Polymerization: Design, Properties and Applications

Investigating the underlying mechanism of biological interactions using glycopolymer is becoming increasingly important owing to their unique recognition properties. The multivalent interactions between lectin and glycopolymer are significantly influenced by...

Para-Fluoro-Thiol Reaction on Anchor Layers Grafted from an Aryldiazonium Salt: A Tool for Surface Functionalization with Thiols

A new coupling reaction, the para-fluoro-thiol (PFT) reaction, activated by base at room temperature, is reported for carbon surface functionalization. 4-Nitrothiophenol (4-NTP) and (3-nitrobenzyl)mercaptan (3-NBM) were coupled to pentafluorophenyl (F₅-Ph) anchor layers grafted from the aryldiazonium ion formed in situ. The relative yields of the PFT reactions, estimated from the electrochemical responses of coupled nitrophenyl (NP) and nitrobenzyl (NB) groups, depended on the nucleophilicity of the thiolate and the strength of the base. The highest surface concentration (4.6 × 10^-10 mol cm^-2) was obtained using 3-NBM in the presence of [Bu₄N]OH; this concentration corresponds to the maximum that is typically achieved for other high-yielding coupling reactions at aryldiazonium ion anchor layers. The PFT reaction is expected to be applicable to the numerous thiol derivatives commonly restricted to self-assembled monolayer (SAM) formation at gold and other noble metals, thereby opening a simple new approach for interface design on carbon substrates. The strategy may also have advantages for modification of gold surfaces: the layer prepared by coupling 3-NBM to F₅-Ph films on gold was found to be more stable to storage under ambient conditions than self-assembled monolayers of 3-NBM.

One-pot synthesis of amphiphilic multiblock poly(2-oxazoline)s via para-fluoro-thiol click reactions

A clickable initiator, pentafluoro benzyl bromide, has been investigated for the cationic ring opening polymerization of poly(2-oxazolines).

Nitroxide-mediated polymerisation of thioacrylates and their transformation into poly(acrylamide)s

Nitroxide mediated polymers of thioacrylates can be transformed into poly(acrylamide)s.

Glyco-nanoparticles: New drug delivery systems in cancer therapy

Cancer is known as one of the most common diseases that are associated with high mobility and mortality in the world. Despite several efforts, current cancer treatment modalities often are highly toxic and lack efficacy and specificity. However, the application of nanotechnology has led to the development of effective nanosized drug delivery systems which are highly selective for tumors and allow a slow release of active anticancer agents. Different Nanoparticles (NPs) such as the silicon-based nano-materials, polymers, liposomes and metal NPs have been designed to deliver anti-cancer drugs to tumor sites. Among different drug delivery systems, carbohydrate-functionalized nanomaterials, specially based on their multi-valent binding capacities and desirable bio-compatibility, have attracted considerable attention as an excellent candidate for controlled release of therapeutic agents. In addition, these carbohydrate functionalized nano-carriers are more compatible with construction of the intracellular delivery platforms like the carbohydrate-modified metal NPs, quantum dots, and magnetic nano-materials. In this review, we discuss recent research in the field of multifunctional glycol-nanoparticles (GNPs) intended for cancer drug delivery applications.

Carbohydrate-based nanocarriers and their application to target macrophages and deliver antimicrobial agents

Many deadly infections are produced by microorganisms capable of sustained survival in macrophages. This reduces exposure to chemadrotherapy, prevents immune detection, and is akin to criminals hiding in police stations. Therefore, the use of glyco-nanoparticles (GNPs) as carriers of therapeutic agents is a burgeoning field. Such an approach can enhance the penetration of drugs into macrophages with specific carbohydrate targeting molecules on the nanocarrier to interact with macrophage lectins. Carbohydrates are natural biological molecules and the key constituents in a large variety of biological events such as cellular communication, infection, inflammation, enzyme trafficking, cellular migration, cancer metastasis and immune functions. The prominent characteristics of carbohydrates including biodegradability, biocompatibility, hydrophilicity and the highly specific interaction of targeting cell-surface receptors support their potential application to drug delivery systems (DDS). This review presents the 21^st century development of carbohydrate-based nanocarriers for drug targeting of therapeutic agents for diseases localized in macrophages. The significance of natural carbohydrate-derived nanoparticles (GNPs) as anti-microbial drug carriers is highlighted in several areas of treatment including tuberculosis, salmonellosis, leishmaniasis, candidiasis, and HIV/AIDS.

Uptake and Intracellular Fate of Engineered Nanoparticles in Mammalian Cells: Capabilities and Limitations of Transmission Electron Microscopy-Polymer-Based Nanoparticles

In order to elucidate mechanisms of nanoparticle (NP)-cell interactions, a detailed knowledge about membrane-particle interactions, intracellular distributions, and nucleus penetration capabilities, etc. becomes indispensable. The utilization of NPs as additives in many consumer products, as well as the increasing interest of tailor-made nanoobjects as novel therapeutic and diagnostic platforms, makes it essential to gain deeper insights about their biological effects. Transmission electron microscopy (TEM) represents an outstanding method to study the uptake and intracellular fate of NPs, since this technique provides a resolution far better than the particle size. Additionally, its capability to highlight ultrastructural details of the cellular interior as well as membrane features is unmatched by other approaches. Here, a summary is provided on studies utilizing TEM to investigate the uptake and mode-of-action of tailor-made polymer nanoparticles in mammalian cells. For this purpose, the capabilities as well as limitations of TEM investigations are discussed to provide a detailed overview on uptake studies of common nanoparticle systems supported by TEM investigations. Furthermore, methodologies that can, in particular, address low-contrast materials in electron microscopy, i.e., polymeric and polymer-modified nanoparticles, are highlighted.

The para-fluoro-thiol reaction as an efficient tool in polymer chemistry

The current literature describing the application of the para-fluoro–thiol reaction in the realm of macromolecular chemistry and the future of this coupling strategy are discussed.

Glyconanoparticles with controlled morphologies and their interactions with a dendritic cell lectin

Well-defined amphiphilic block glycopolymers with equal mannose content have been self-assembled in aqueous solution to form glyconanoparticles with different morphologies.

Stable monodisperse nanomagnetic colloidal suspensions: An overview

Magnetic iron oxide nanoparticles (MNPs) have emerged as highly desirable nanomaterials in the context of many research works, due to their extensive industrial applications. However, they are prone to agglomerate on account of the anisotropic dipolar attraction, and therefore misled the particular properties related to single-domain magnetic nanostructures. The surface modification of MNPs is quite challenging for many applications, as it involves surfactant-coating for steric stability, or surface modifications that results in repulsive electrostatic force. Hereby, we focus on the dispersion of MNPs and colloidal stability.

Lignocellulosic biomass: a sustainable platform for the production of bio-based chemicals and polymers

The ongoing research activities in the field of lignocellulosic biomass for production of value-added chemicals and polymers that can be utilized to replace petroleum-based materials are reviewed.

Preparation of emissive glucose-containing polymer nanoparticles and their cell imaging applications

Water dispersible, bright and biocompatible fluorescent glycopolymer nanoparticles were facilely fabricated, and their cellular imaging application was successfully demonstrated.

Glyconanoparticles and their interactions with lectins

Glyconanoparticles and their interactions with lectins.

Red fluorescent cross-linked glycopolymer nanoparticles based on aggregation induced emission dyes for cell imaging

Aggregation induced emission dye based cross-linked fluorescent glycopolymer nanoparticles with red emission: their synthesis, characterization and application for cell imaging.

Convergent diversity-oriented side-chain macrocyclization scan for unprotected polypeptides

Here we describe a general synthetic platform for side-chain macrocyclization of an unprotected peptide library based on the SNAr reaction between cysteine thiolates and a new generation of highly reactive perfluoroaromatic small molecule linkers. This strategy enabled us to simultaneously "scan" two cysteine residues positioned from i, i + 1 to i, i + 14 sites in a polypeptide, producing 98 macrocyclic products from reactions of 14 peptides with 7 linkers. A complementary reverse strategy was developed; cysteine residues within the polypeptide were first modified with non-bridging perfluoroaryl moieties and then commercially available dithiol linkers were used for macrocyclization. The highly convergent, site-independent, and modular nature of these two strategies coupled with the unique chemoselectivity of a SNAr transformation allows for the rapid diversity-oriented synthesis of hybrid macrocyclic peptide libraries with varied chemical and structural complexities.

Fabrication of structured porous films by breath figures and phase separation processes: tuning the chemistry and morphology inside the pores using click chemistry

Herein, a facile water-assisted templating technique, the so-called breath figures method, in combination with phase separation process, was employed to prepare multifunctional micropatterned films. Tetrahydrofuran solutions of incompatible ternary blends consisting of high-molecular-weight polystyrene, an amphiphilic block copolymer, polystyrene-b-poly[poly(ethylene glycol) methyl ether methacrylate] (PS40-b-P(PEGMA300)48), and a fluorinated homopolymer, poly(2,3,4,5,6-pentafluorostyrene) (P5FS21) were casted under humid atmosphere varying the proportion of the components. Two simultaneously occurring processes, i.e., the breath figures mechanism and the phase separation process, lead to unprecedented morphologies that could be tuned by simply varying the relative humidity or the composition of the blend. Confocal micro-Raman spectroscopy served to provide information about the location and distribution of the different functionalities in the films. As a result, both the amphiphilic block copolymer and the fluorinated polymer were mainly located in the cavities. Above a certain percentage of relative humidity, honeycomb structured films were obtained in which the block copolymer is distributed on the edge of the pore as a result of the affinity by the condensing water droplet and the coffee stain effect. The homopolymer is also preferentially situated at the pore edge, but forming spherical domains with narrow polydisperse sizes. Moreover, thiolated glucose molecules were specifically attached to the P5FS21 domains via thiol-para fluorine "click" reaction. Subsequently, the specific lectin (Concanavalin A, Canavalia ensiformis) was attached to the surface by conjugation with the glucose moieties. The successful binding of the Con A was demonstrated by the fluorescence, observed exclusively at the areas where P5FS21 domains are located. This nonlithographic method opens a new route to fabricate a huge variety of microstructured polymer films in terms of morphology not only for protein patterning, as illustrated in this manuscript, but also to produce a diversity of functional group arrangements.

In situ functionalization and PEO coating of iron oxide nanocrystals using seeded emulsion polymerization

Herein we demonstrate that seeded emulsion polymerization is a powerful tool to produce multiply functionalized PEO coated iron oxide nanocrystals. Advantageously, by simple addition of functional surfactants, functional monomers, or functional polymerizable linkers-solely or in combinations thereof-during the seeded emulsion polymerization process, a broad range of in situ functionalized polymer-coated iron oxide nanocrystals were obtained. This was demonstrated by purposeful modulation of the zeta potential of encapsulated iron oxide nanocrystals and conjugation of a dyestuff. Successful functionalization was unequivocally proven by TXRF. Furthermore, the spatial position of the functional groups can be controlled by choosing the appropriate spacers. In conclusion, this methodology is highly amenable for combinatorial strategies and will spur rapid expedited synthesis and purposeful optimization of a broad scope of nanocrystals.

Memory-effects of magnetic nanocomposites

The thermally induced shape memory effect (SME) is the capability of a material to fix a temporary (deformed) shape and recover a 'memorized' permanent shape in response to heat. SMEs in polymers have enabled a variety of applications including deployable space structures, biomedical devices, adaptive optical devices, smart dry adhesives and fasteners. By the incorporation of magnetic nanoparticles (mNP) into shape-memory polymer (SMP), a magnetically controlled SME has been realized. Magnetic actuation of nanocomposites enables remotely controlled devices based on SMP, which might be useful in medical technology, e.g. remotely controlled catheters or drug delivery systems. Here, an overview of the recent advances in the field of magnetic actuation of SMP is presented. Special emphasis is given on the magnetically controlled recovery of SMP with one switching temperature T(sw) (dual-shape effect) or with two T(sw)s (triple-shape effect). The use of magnetic field to change the apparent switching temperature (T(sw,app)) of the dual or triple-shape nanocomposites is described. Finally, the capability of magnetic nanocomposites to remember the magnetic field strength (H) initially used to deform the sample (magnetic-memory effect) is addressed. The distinguished advantages of magnetic heating over conventional heating methods make these multifunctional nanocomposites attractive candidates for in vivo applications.

Synthesis of a glycopolymeric Pt(II) carrier and its induction of apoptosis in resistant cancer cells

Post-polymerization modification of a poly(pentafluorostyryl) backbone with β-d-galactose and a terpyridine platinum complex yields a well-defined material that represents the first example of a metal-conjugated glycopolymer. It reveals anti-proliferative activity, no detectable necrotic cytotoxicity, and efficiently induces apoptosis in both wild-type as well as resistant Nalm-6 leukemia cell lines.