Encapsulation with polymers is a well-known strategy to stabilize and functionalize nanomaterials and tune their physicochemical properties. Amphiphilic copolymers are promising in this context, but their structural diversity and complexity also make understanding and predicting their behavior challenging. This is particularly the case in complex media which are relevant for intended applications in medicine and nanobiotechnology. Here, we studied the encapsulation of gold nanoparticles and quantum dots with amphiphilic copolymers differing in their charge and molecular structure. Protein adsorption to the nanoconjugates was studied with fluorescence correlation spectroscopy, and their surface activity was studied with dynamic interfacial tensiometry. Encapsulation of the nanoparticles without affecting their characteristic properties was possible with all tested polymers and provided good stabilization. However, the interaction with proteins and cells significantly depended on structural details. We identified statistical copolymers providing strongly reduced protein adsorption and low unspecific cellular uptake. Interestingly, different zwitterionic amphiphilic copolymers showed substantial differences in their resulting bio-repulsive properties. Among the polymers tested herein, statistical copolymers with sulfobetaine and phosphatidylcholine sidechains performed better than copolymers with carboxylic acid- and dimethylamino-terminated sidechains.

To study charge-dependent interactions of nanoparticles (NPs) with biological media and NP uptake by cells, colloidal gold nanoparticles were modified with amphiphilic polymers to obtain NPs with identical physical properties except for the sign of the charge (negative/positive). This strategy enabled us to solely assess the influence of charge on the interactions of the NPs with proteins and cells, without interference by other effects such as different size and colloidal stability. Our study shows that the number of adsorbed human serum albumin molecules per NP was not influenced by their surface charge. Positively charged NPs were incorporated by cells to a larger extent than negatively charged ones, both in serum-free and serum-containing media. Consequently, with and without protein corona (i.e., in serum-free medium) present, NP internalization depends on the sign of charge. The uptake rate of NPs by cells was higher for positively than for negatively charged NPs. Furthermore, cytotoxicity assays revealed a higher cytotoxicity for positively charged NPs, associated with their enhanced uptake.

ConspectusThe ligand shells of colloidal nanoparticles (NPs) can serve different purposes. In general, they provide colloidal stability by introducing steric repulsion between NPs. In the context of biological applications, the ligand shell plays a critical role in targeting, enabling NPs to achieve specific biodistributions. However, there is also another important feature of the ligand shell of NPs, namely, the creation of a local environment differing from the bulk of the solvent in which the NPs are dispersed. It is known that charged ligand shells can attract or repel ions and change the effective charge of a NP through Debye–Hückel screening. Positively charged ions, such as H+ (or H3O+) are attracted to negatively charged surfaces, whereas negatively charged ions, such as Cl– are repelled. The distribution of the ions around charged NP surfaces is a radial function of distance from the center of the NP, which is governed by a balance of electrostatic forces and entropy of ions and ligands. As a result, the ion concentration at the NP surface is different from its bulk equilibrium concentration, i.e., the charged ligand shell around the NPs has formed a distinct local environment. This not only applies to charged ligand shells but also follows a more general principle of induced condensation and depletion. Polar/apolar ligand shells, for example, result in a locally increased concentration of polar/apolar molecules. Similar effects can be seen for biocatalysts like enzymes immobilized in nanoporous host structures, which provide a special environment due to their surface chemistry and geometrical nanoconfinement. The formation of a local environment close to the ligand shell of NPs has profound implications for NP sensing applications. As a result, analyte concentrations close to the ligand shell, which are the ones that are measured, may be very different from the analyte concentrations in bulk. Based on previous work describing this effect, it will be discussed herein how such local environments, created by the choice of used ligands, may allow for tailoring the NPs' sensing properties. In general, the ligand shell around NPs can be attractive/repulsive for molecules with distinct properties and thus forms an environment that can modulate the specific response. Such local environments can also be optimized to modulate chemical reactions close to the NP surface (for example, by size filtering within pores) or to attract specific low abundance proteins. The importance hereby is that this is based on interaction with low selectivity between the ligands and the target molecules.

Amphiphilic copolymers with various charged side chains have been synthesized and used for the coating of initially hydrophobic gold nanoparticles (Au NPs) to stabilize them in aqueous solution. These amphiphilic copolymers are composed of functionalized methacrylic acid-based monomers that are either hydrophobic or hydrophilic and charged: zwitterionic, positive and negative. Not only was the charge of the monomers varied, but also the ratio of the hydrophobic and hydrophilic moieties within the copolymers in order to investigate the effect of the charge density of the NP surface on its stability. To learn more about the interactions between the coated NPs and their surrounding environment, the physico-chemical properties, e.g. zeta potential, of the NPs' polymeric shell and their influence on the NPs' behavior were studied. The stability of the resulting polymer-coated Au NPs against several aqueous media has been tested to obtain a better understanding about the parameters that influence the dispersion of the NPs. Stability tests were performed at different conditions e.g., at different pH, against different NaCl concentrations, and at different concentrations of bovine serum albumin (BSA), which was used as a protein model. Understanding the surface interactions of nanostructures with the environment, is of importance when it comes to introduction of nanosystems into complex biological structures like the internalization of nanometric structures within cells.

With a bifunctional symmetric RAFT agent well-defined polymer structures can be achieved. This paper shows the possibility to synthesize block copolymer systems consisting out of different activated monomers. With the novel bifunctional symmetric RAFT agent water-born polymer systems with a block structure (B-b-A-b-B) can be polymerized. The symmetric RAFT agent is designed to polymerize both more activated monomers (A) and less activated monomers (B). Due to the ability of a controlled radical polymerization of different activated monomers the dispersity of the resulting polymers is broader compared to common RAFT polymerizations. In regard to industrial applications like emulsifiers, stabilizers or viscosity modifiers the broader molecular weight distribution has no impact. Overall, this paper shows the possibility towards new functional polymers with unique properties.

A procedure to obtain very uniform polyolefin copolymers by supported metallocenes is presented. Conventional metallocene or Ziegler-Natta catalysts, both immobilized on inorganic supports, yield only copolymers with inhomogeneous comonomer incorporation and broad short-chain branching distribution. The main reasons are diffusional limitations of the monomers or the multisite character of the catalysts. By comparing inorganic and organic supports, we demonstrate that metallocenes immobilized on organic supports solve these problems. In this regard, organic and soft nanosized polystyrene particles (nPS) versus industrially used, hard, and inorganic SiO2 were used to support [Me2Si(Ind)(2)ZrCl2/MAO (I) and Me2Si(Benz[e]-Ind)(2)ZrCl2/MAO (BI)] catalysts for ethylene/1-hexene copolymerization. In the inorganic case, the catalyst systems show a substantial inconsistency in the copolymers' branching distribution, resulting in phase separation. One phase is hexene-poor with high melting temperature (T-m) and high molecular weight (MW). The second, hexene-rich phase, however, shows lower T-m and MW. By using organic supports, comonomers are uniformly inserted into the polymer chain and homogeneous microstructured copolymers are obtained. These findings are mainly attributed to diffusion processes of the monomers into the soft organic material. To prove this conclusion and to elucidate the structure of the catalyst system, various characterization techniques such as time-of-flight secondary ion mass spectrometry and scanning electron microscopy-energy-dispersive X-ray were performed.

A route of synthesizing molecular bottlebrush polymers in a one-pot, one-step polymerization approach is presented. Through the combination of two orthogonal polymerization techniques, the backbone and side chains can be synthesized at the same time. Both polymerizations have to be compatible regarding mechanisms, chosen monomers, and solvents. Here, the mutual compatibility of the heat activated 2,4-dihydro-2,4,5-triphenyl-1,2,4-triazol-3-ylidene-catalyzed ring-opening polymerization with the ring-opening metathesis polymerization initiated by the third-generation Grubbs catalyst is demonstrated. Molecular bottlebrushes were synthesized with different lengths of poly(L-lactide) side chains and various poly(N-(hydroxylethyl)-cis-5-norbornene-exo-2,3-dicarboximide) backbone lengths. Their synthesis was achieved both in a one-pot grafting through approach as well as through the simultaneous ring-opening polymerization and ring-opening metathesis polymerization. The simultaneous bottlebrush polymerizations yielded short molecular bottlebrushes with excellent control and dispersities between 1.07 and 1.15. The reaction was followed by in situ H-1 NMR.

For nanoparticles that are used as intravascular drug delivery systems, aggregation resulting in carrier sizes >250 nm is a serious issue as those systems are removed from the blood stream by Kupffer cells.[4]Herein, we describe the synthesis of polylactide particles decorated by a polyglutamic acid corona by non-aqueous emulsion polymerization.While in many other approaches polypeptides are either after particle formation adsorbed or grafted herein we us a specially designed emulsifier to form a polypeptide shell.A light sensitive PEG-block-poly((1-pyrenyl methyl) glutamate) (PEG-b-PGlu(Pyr)) copolymer is synthesized and used as emulsifier in a nonaqueous emulsion polymerization of lactide which is required due to the moisture sensitivity of the polymerization catalysts.Poly(L-lactide) (PLLA) nanoparticles were synthesized via ring-opening polymerization of L-lactide with a moisture-sensitive catalyst in a non-aqueous emulsion consisting of acetonitrile, cyclohexane, and the PEG-b-PGlu(Pyr) copolymer as emulsifier.Upon UV irradiation, hydrophobic pyrenyl methylene units are cleaved from the block copolymer, resulting in a polarity reversal of the particle surface from hydrophobic to hydrophilic.The product particles have a fully hydrophilic and biocompatible PEG-b-PGlu shell and can be dispersed in water without aggregation.Furthermore, introducing MMP-3 cleavable peptide sequences in the nanoparticles allows for a full degradation of the particles when they are getting close to tumor cells.This offers the opportunity to selectively release drugs which have already been incorporated before during in the particle formation.The particles consist exclusively of non-toxic biodegradable polymes (polylactide and polypeptide making them suitable candidates for medical applications in particular for cancer therapy.

Abstract Oilfield iron sulfide (FeS) control and prevention have been mostly proprietary with several disparate solutions. Frequently FeS control involves milling, jetting, acid soaking, pulling and replacing tubing and manually cleaning tanks, vessels, separators and pumps. These methods are costly, wasteful and strenuous. This paper reviews the latest developments in oilfield FeS researches with an attempt to integrate viable solutions and expose unworkable practices. In this work, we review and evaluate the most common FeS prevention and control solutions in an attempt to summarize the state-of-art FeS mitigation technologies. We have a closer look on FeS formation and control as well as potential integrated solutions. The paper reviews and differentiates treatment solutions between corrosion byproduct and FeS scale deposition from formation. Most FeS scales have generally been treated as the same, using various treatment methods. Complex FeS polymorphs have resulted in different outcomes. This work focuses on different treatment options that assert to work for all FeS scale not differentiating between corrosion-byproduct and reservoir formed scale. Successful case histories and suspected FeS polymorph are presented in this paper next to discussion of the model used to predict severity of the deposition and analyze the treatment design. FeS formation and deposition is evaluated, especially crystallography and fundamental studies into mechanistic aspects of FeS precipitation and how it relates to oilfield FeS precipitation. In this paper state-of-art FeS scale research is summarized and differences to normal scale types are presented. Mineral scale in the true sense of going through the stages of nucleation, pre-crystallization, crystal growth, agglomeration and deposition. This is an important step change in consolidating all the disparate areas of FeS studies into an advanced solution focused approach. If FeS scale is considered a mineral scale then solutions such as scale inhibitor applications (continuous injection and squeeze) that work for common mineral scales should work for FeS deposition as well. Thereby moving FeS research from a relatively empirical level with vastly different approaches that are mostly unrealistic into solutions that will be viable in the oilfield.

The phenomenon of self-assembly and disassembly was employed to investigate the proton conduction in organic phosphonic acids decorated with lyophilic hydrocarbon chains.

The recent design and stepwise development of nanocarriers by fulfilling the mandatory requirements like biocompatibility, size, functionality and favorable surface characteristics were comprehensively described in order to demonstrate the selective drug release profile at tumor tissues. Employing nonaqueous emulsion as a tool, biocompatible polylactide nanoparticles were synthesized with an appropriate size and shape. Block copolymerization of L-lactide using a model bifunctional peptide initiator resulted in triblock copolymer nanoparticles, which were loaded with dye during the emulsion process to investigate the cargo release and cell internalization properties. Afterwards, introducing the specific cleavable peptide sequences into the particles allow us to achieve triggered drug release by Matrix MetalloProteinase-2 (MMP-2), which is an overexpressed enzyme in tumor tissues. Finally, biocompatible emulsifiers for the nonaqueous emulsion were described. They were able to change their polarity from hydrophobic to hydrophilic by irradiation and, therefore, facilitate the transfer of the particles from nonaqueous to aqueous media by light-induced processes.

Given their increasing importance in a variety of applications, the preparation of carbon fibers with well-defined chemical structures and innocuous byproducts has garnered a growing interest over the past decade. We report the preparation of medium molecular weight poly(methyl vinyl ketone) (PMVK) as a potential carbon fiber precursor material which can easily undergo carbonization via the well-known, acid-catalyzed aldol condensation with water as a sole byproduct. Rheological studies further show that PMVK (MW ∼ 50 kg/mol) exhibits excellent physical and thermal properties for the spinning of single and multifilament fibers and easily produces carbon yields of 25% at temperatures as low as 250 °C. Analysis of the carbonized product also suggests a more defect-free structure than commercially available carbon fibers.

Numerous catechol-containing polymers, including biodegradable polymers, are currently heavily discussed for modern biomaterials. However, there is no report combining poly(phosphoester)s (PPEs) with catechols. Adhesive PPEs have been prepared via acyclic diene metathesis polymerization. A novel acetal-protected catechol phosphate monomer was homo- and copolymerized with phosphoester comonomers with molecular weights up to 42000 g/mol. Quantitative release of the catechols was achieved by careful hydrolysis of the acetal groups without backbone degradation. Degradation of the PPEs under basic conditions revealed complete and statistical degradation of the phosphotri- to phosphodiesters. In addition, a phosphodiester monomer with an adhesive P-OH group and no protective group chemistry was used to compare the binding to metal oxides with the multicatechol-PPEs. All PPEs can stabilize magnetite particles (NPs) in polar solvents, for example, methanol, due to the binding of the phosphoester groups in the backbone to the particles. ITC measurements reveal that multicatechol PPEs exhibit a higher binding affinity to magnetite NPs compared to PPEs bearing phosphodi- or phosphotriesters as repeating units. In addition, the catechol-containing PPEs were used to generate organo- and hydrogels by oxidative cross-linking, due to cohesive properties of catechol groups. This unique combination of two natural adhesive motives, catechols and phosphates, will allow the design of novel future gels for tissue engineering applications or novel degradable adhesives.