Building Bridges by Blending: Morphology and Mechanical Properties of Binary Tapered Diblock/Multiblock Copolymer Blends

This work explores the scope and limitations of enhancing the poor mechanical properties of diblock copolymers by blending with tapered multiblock copolymers of styrene (S) and isoprene (I), P(I‐co‐S)n. Blending of different tapered diblock copolymers (n = 1; Mn = 80 and 240 kg mol⁻¹, 50 wt% polyisoprene (PI) units, lamellar morphologies) affords brittle materials with low elongation at break. An increasing degree of phase separation from (i) miscible P(I‐co‐S)/P(I‐co‐S)n copolymer blends, to (ii) partially miscible and (iii) finally immiscible blends is studied. The effect of miscibility on the mechanical properties is studied for two diblock copolymers (Mn = 80 and 240 kg mol⁻¹, domain spacing of 38 and 77 nm, respectively), blended with a series of multiblock copolymers P(I‐co‐S)n (n = 2–5; domain spacing of 42 to 20 nm) of similar molecular weight. Increasing disparity in the domain spacing results in partially miscible and finally immiscible blends. Immiscibility causes lower elongation at break, albeit superior tensile properties compared to the pure tapered diblock copolymers are maintained. The study shows that the addition of a minor fraction of multiblock copolymers to diblock copolymers is a versatile method toward improved mechanical properties, while retaining an ordered nanophase‐separated morphology

Inhalable nano-structured microparticles for extracellular matrix modulation as a potential delivery system for lung cancer

The use of inhalable nanoparticulate-based systems in the treatment of lung cancer allows for efficient localized delivery to the lungs with less undesirable systemic exposure. For this to be attained, the inhaled particles should have optimum properties for deposition and at the same time avoid pulmonary clearance mechanisms. Drug delivery to solid tumors is furthermore challenging, due to dense extracellular matrix (ECM) formation, which hinders the penetration and diffusion of therapeutic agents. To this end, the aim of the current work is to develop an ECM-modulating nano-structured microparticulate carrier, that not only enables the delivery of therapeutic nanoparticles (NPs) to the lungs, but also enhances their intratumoral penetration. The system is composed of acetalated maltodextrin (AcMD) NPs embedded into a water-soluble trehalose/leucine matrix, in which collagenase was loaded with different mass concentrations (10 %, 30 % and 50 %). The collagenase-containing AcMD nano-structured microparticles (MPs) exhibited suitable median volume diameters (2.58 ± 1.35 to 3.01 ± 0.68 µm), hollow corrugated morphology, sufficient redispersibility, low residual moisture content (2.71 ± 0.17 % to 3.10 ± 0.20 %), and favorable aerodynamic properties (Mass median aerodynamic diameter (MMAD): 1.93 ± 0.06 to 2.80 ± 0.10 µm and fine particle fraction (FPF): 68.02 ± 6.86 % to 69.62 ± 2.01 %). Importantly, collagenase retained as high as 89.5 ± 6.7 % of its enzymatic activity after spray drying. MPs containing 10 % mass content of collagenase did not show signs of cytotoxicity on either human lung adenocarcinoma A549 cells or lung MRC-5 fibroblasts. The nanoparticle penetration was tested using adenocarcinoma A549/MRC-5 co-culture spheroid model, where the inclusion of collagenase resulted in deeper penetration depth of AcMD-NPs

Serological profile of torque teno sus virus species 1 (TTSuV1) in pigs and antigenic relationships between two TTSuV1 genotypes (1a and 1b), between two species (TTSuV1 and -2), and between porcine and human anelloviruses

The family Anelloviridae includes human and animal torque teno viruses (TTVs) with extensive genetic diversity. The antigenic diversity among anelloviruses has never been assessed. Using torque teno sus virus (TTSuV) as a model, we describe here the first investigation of the antigenic relationships among different anelloviruses. Using a TTSuV genotype 1a (TTSuV1a) or TTSuV1b enzyme-linked immunosorbent assay (ELISA) based on the respective putative ORF1 capsid antigen and TTSuV1-specific real-time PCR, the combined serological and virological profile of TTSuV1 infection in pigs was determined and compared with that of TTSuV2. TTSuV1 is likely not associated with porcine circovirus-associated disease (PCVAD), because both the viral loads and antibody levels were not different between affected and unaffected pigs and because there was no synergistic effect of concurrent PCV2/TTSuV1 infections. We did observe a higher correlation of IgG antibody levels between anti-TTSuV1a and -TTSuV1b than between anti-TTSuV1a or -1b and anti-TTSuV2 antibodies in these sera, implying potential antigenic cross-reactivity. To confirm this, rabbit antisera against the putative capsid proteins of TTSuV1a, TTSuV1b, or TTSuV2 were generated, and the antigenic relationships among these TTSuVs were analyzed by an ELISA and by an immunofluorescence assay (IFA) using PK-15 cells transfected with one of the three TTSuV ORF1 constructs. The results demonstrate antigenic cross-reactivity between the two genotypes TTSuV1a and TTSuV1b but not between the two species TTSuV1a or -1b and TTSuV2. Furthermore, an anti-genogroup 1 human TTV antiserum did not react with any of the three TTSuV antigens. These results have important implications for an understanding of the diversity of anelloviruses as well as for the classification and vaccine development of TTSuVs

Rescue of a porcine anellovirus (torque teno sus virus 2) from cloned genomic DNA in pigs

Anelloviruses are a group of single-stranded circular DNA viruses infecting humans and other animal species. Animal models combined with reverse genetic systems of anellovirus have not been developed. We report here the construction and initial characterization of full-length DNA clones of a porcine anellovirus, torque teno sus virus 2 (TTSuV2), in vitro and in vivo. We first demonstrated that five cell lines, including PK-15 cells, are free of TTSuV1 or TTSuV2 contamination, as determined by a real-time PCR and an immunofluorescence assay (IFA) using anti-TTSuV antibodies. Recombinant plasmids harboring monomeric or tandem-dimerized genomic DNA of TTSuV2 from the United States and Germany were constructed. Circular TTSuV2 genomic DNA with or without introduced genetic markers and tandem-dimerized TTSuV2 plasmids were transfected into PK-15 cells, respectively. Splicing of viral mRNAs was identified in transfected cells. Expression of TTSuV2-specific open reading frame 1 (ORF1) in cell nuclei, especially in nucleoli, was detected by IFA. However, evidence of productive TTSuV2 infection was not observed in 12 different cell lines transfected with the TTSuV2 DNA clones. Transfection with circular DNA from a TTSuV2 deletion mutant did not produce ORF1 protein, suggesting that the observed ORF1 expression is driven by TTSuV2 DNA replication in cells. Pigs inoculated with either the tandem-dimerized clones or circular genomic DNA of U.S. TTSuV2 developed viremia, and the introduced genetic markers were retained in viral DNA recovered from the sera of infected pigs. The availability of an infectious DNA clone of TTSuV2 will facilitate future study of porcine anellovirus pathogenesis and biology

The Core Protein of Classical Swine Fever Virus Is Dispensable for Virus Propagation In Vitro

Core protein of Flaviviridae is regarded as essential factor for nucleocapsid formation. Yet, core protein is not encoded by all isolates (GBV- A and GBV- C). Pestiviruses are a genus within the family Flaviviridae that affect cloven-hoofed animals, causing economically important diseases like classical swine fever (CSF) and bovine viral diarrhea (BVD). Recent findings describe the ability of NS3 of classical swine fever virus (CSFV) to compensate for disabling size increase of core protein (Riedel et al., 2010). NS3 is a nonstructural protein possessing protease, helicase and NTPase activity and a key player in virus replication. A role of NS3 in particle morphogenesis has also been described for other members of the Flaviviridae (Patkar et al., 2008; Ma et al., 2008). These findings raise questions about the necessity and function of core protein and the role of NS3 in particle assembly. A reverse genetic system for CSFV was employed to generate poorly growing CSFVs by modification of the core gene. After passaging, rescued viruses had acquired single amino acid substitutions (SAAS) within NS3 helicase subdomain 3. Upon introduction of these SAAS in a nonviable CSFV with deletion of almost the entire core gene (Vp447Δc), virus could be rescued. Further characterization of this virus with regard to its physical properties, morphology and behavior in cell culture did not reveal major differences between wildtype (Vp447) and Vp447Δc. Upon infection of the natural host, Vp447Δc was attenuated. Hence we conclude that core protein is not essential for particle assembly of a core-encoding member of the Flaviviridae, but important for its virulence. This raises questions about capsid structure and necessity, the role of NS3 in particle assembly and the function of core protein in general

Pressure Induced Structure Formation in Langmuir Monolayers of Amphiphilic Metallocene Diblock Copolymers

We present in situ structural investigations of a metal-containing diblock copolymer on a water surface. Mono layers of poly(vinylferrocene-b-(2-vinylpyridine)) (PVFc-b-P2VP) block copolymers are studied in a wide range of compositions by varying molar masses of P2VP with two different molecular weights of PVFc. We focus on the role of the respective block partners, PVFc and P2VP, when compressing the layer on the water surface. Compression isotherms are presented and interpreted in terms of the classical gaseous, expanded, and condensed phases. We calculate isothermal compressibilities, which reveal a minimum value independent of the molar masses of the respective block partners. We find the isotherms to be dominated by P2VP while PVFc barely contribute to the compression behavior due to its rather compact coil structure. We consider the diblock copolymer monolayers as a two-dimensional model system, which is reflected by two-dimensional scaling behavior in the semi dilute and condensed regime. By X-ray reflectometry (XR), we monitor in situ the monolayer structure change with increasing surface pressure Pi and observe the PVFc-b-P2VP separation at high Pi

Single-source macroporous hybrid materials by melt-shear organization of core-shell particles

The preparation of porous materials is an interesting field for a huge variety of potential applications. Herein we report an efficient and convenient strategy for the creation of inverse colloidal crystal structures based on soft core/shell polymer particle templating. This single-source strategy is based on starved-feed emulsion polymerization of hybrid core/shell particles consisting of a poly(methyl methacrylate-co-allyl methacrylate) (P(MMA-co-ALMA)) core and a poly(ethyl acrylate-co-(3-methacryloxypropyl-trimethoxysilane)) (PEA-co-PMEMO) shell. The resulting monodisperse particles are analyzed with respect to their size and distribution by transmission electron microscopy (TEM) and dynamic light scattering (DLS) measurements. The hybrid monodisperse core/shell particles can be aligned to a colloidal crystal by using the convenient melt-shear organization technique. As a result, free-standing and crack-free hybrid polymer colloidal crystal films are accessible without the need of any solvent or dispersion medium. The processing step is investigated regarding different parameters comprising temperature and pressure for the influence on the colloidal crystal film formation. Furthermore, resulting core/shell ratio is tailored by starved-feed emulsion polymerization conditions, since the ratio affects the quality of the porous structure after thermal treatment of colloidal crystal films. The incorporation of alkoxysilane-containing monomers offers a unique crosslinking strategy that yields mechanically robust and thermally stable films. Due to the increased stability, a removal of PMMA cores is possible by thermal treatment of the templating colloidal crystal films leading to almost isoporous free-standing hybrid materials as determined by thermogravimetric analysis (TGA) and scanning electron microscopy (SEM)