Star-Brush-Shaped Macromolecules: Peculiar Properties in Dilute Solution

Star-brush-shaped poly­(ε-caprolactone)-<i>block</i>-poly­(oligo­(ethylene glycol) methacrylate (PCL-<i>b</i>-POEGMA) macromolecules were synthesized and studied by molecular hydrodynamic methods. The values of the intrinsic viscosity, the velocity sedimentation coefficient, the translational diffusion coefficient, and the frictional ratio were obtained in acetone. Molar masses (<i>M</i>) were determined by the Svedberg relation, and the correlations between the hydrodynamic values and the molar mass were obtained in the range of 19 < <i>M</i> × 10^–3 g mol^–1 < 124. Comparison of the scaling indexes of the intrinsic viscosity and sedimentation velocity coefficient versus molar mass corresponding to the conventional four-arm stars macromolecules with that of the star-brush-shaped copolymer macromolecules shows that the star-brush-shaped PCL-<i>b</i>-POEGMA macromolecules have the more dense organization in space which is connected with their different topology in contrast to the conventional stars macromolecules. The model of the PCL-<i>b</i>-POEGMA macromolecules based on the ensemble of their hydrodynamic characteristics is discussed

COCONUTAn Efficient Tool for Estimating Copolymer Compositions from Mass Spectra

The accurate characterization of synthetic polymer sequences represents a major challenge in polymer science. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is frequently used for the characterization of copolymer samples. We present the COCONUT software for estimating the composition distribution of the copolymer. Our method is based on Linear Programming and is capable of automatically resolving overlapping isotopes and isobaric ions. We demonstrate that COCONUT is well suited for analyzing complex copolymer MS spectra. COCONUT is freely available and provides a graphical user interface

Star-Shaped Drug Carriers for Doxorubicin with POEGMA and POEtOxMA Brush-like Shells: A Structural, Physical, and Biological Comparison

The synthesis of amphiphilic star-shaped poly­(ε-caprolactone)-<i>block</i>-poly­(oligo­(ethylene glycol)­methacrylate)­s ([PCL₁₈-<i>b</i>-POEGMA]₄) and poly­(ε-caprolactone)-<i>block</i>-poly­(oligo­(2-ethyl-2-oxazoline)­methacrylate)­s ([PCL₁₈-<i>b</i>-POEtOxMA]₄) is presented. Unimolecular behavior in aqueous systems is observed with the tendency to form loose aggregates for both hydrophilic shell types. The comparison of OEGMA and OEtOxMA reveals that the molar mass of the macromonomer in the hydrophilic shell rather than the mere length is the crucial factor to form an efficiently stabilizing hydrophilic shell. A hydrophilic/lipophilic balance of 0.8 is shown to stabilize unimolecular micelles in water. An extensive in vitro biological evaluation shows neither blood nor cytotoxicity. The applicability of the polymers as drug delivery systems was proven by the encapsulation of the anticancer drug doxorubicin, whose cytotoxic effect was retarded in comparison to the free drug

4-Deoxyaurone Formation in <i>Bidens ferulifolia</i> (Jacq.) DC

<div><p>The formation of 4-deoxyaurones, which serve as UV nectar guides in <i>Bidens ferulifolia</i> (Jacq.) DC., was established by combination of UV photography, mass spectrometry, and biochemical assays and the key step in aurone formation was studied. The yellow flowering ornamental plant accumulates deoxy type anthochlor pigments (6′-deoxychalcones and the corresponding 4-deoxyaurones) in the basal part of the flower surface whilst the apex contains only yellow carotenoids. For UV sensitive pollinating insects, this appears as a bicoloured floral pattern which can be visualized in situ by specific ammonia staining of the anthochlor pigments. The petal back side, in contrast, shows a faintly UV absorbing centre and UV absorbing rays along the otherwise UV reflecting petal apex. Matrix-free UV laser desorption/ionisation mass spectrometric imaging (LDI-MSI) indicated the presence of 9 anthochlors in the UV absorbing areas. The prevalent pigments were derivatives of okanin and maritimetin. Enzyme preparations from flowers, leaves, stems and roots of <i>B. ferulifolia</i> and from plants, which do not accumulate aurones e.g. <i>Arabidopsis thaliana</i>, were able to convert chalcones to aurones. Thus, aurone formation could be catalyzed by a widespread enzyme and seems to depend mainly on a specific biochemical background, which favours the formation of aurones at the expense of flavonoids. In contrast to 4-hydroxyaurone formation, hydroxylation and oxidative cyclization to the 4-deoxyaurones does not occur in one single step but is catalyzed by two separate enzymes, chalcone 3-hydroxylase and aurone synthase (catechol oxidase reaction). Aurone formation shows an optimum at pH 7.5 or above, which is another striking contrast to 4-hydroxyaurone formation in <i>Antirrhinum majus</i> L. This is the first example of a plant catechol oxidase type enzyme being involved in the flavonoid pathway and in an anabolic reaction in general.</p></div

HPLC chromatograms from incubation of enzyme preparations.

<p><i>Bidens ferulifolia</i> petals (a) and leaves (b), <i>Antirrhinum majus</i> petals (c) and leaves (d), <i>Arabidopsis thaliana</i> col-0 plants (e), <i>Tagetes erecta</i> petals (f), <i>Dianthus caryophyllus</i> petals (g), and <i>Petunia hybrida</i> petals (h) with butein and of enzyme preparations from <i>B. ferulifolia</i> petals (i) and <i>Antirrhinum majus</i> petals (j) with isoliquiritigenin.</p

Spatial distribution of okanin (<i>m/z</i> 287) along a <i>Bidens ferulifolia</i> petal fixed by adhesive tape on a Indium Tin Oxide glass slide.

<p>first row: front side, second row: back side; from left to right: daylight photos, UV photos, negative ion mode LDI-MSI images (green area indicates the presence of the target compound), negative ion mode LDI-MSI images overlapping the daylight photos. All mass peaks related to anthochlors showed a similar distribution.</p

LDI-MS of a <i>Bidens ferulifolia</i> petal.

<p>a: a representative spectrum of the petal base containing nine <i>m/z</i> signals of anthochlors. b: no anthochlors were detected in representative spectra of the petal apex. For the allocation of <i>m/z</i> signals to compounds refer to <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0061766#pone-0061766-g001" target="_blank">Figure 1</a>.</p

Overview on flavonoid and anthochlor formation from <i>p</i>-coumaroyl-CoA.

<p>abbrev.: ANS: anthocyanidin synthase, AUS: aurone synthase, CH3H: chalcone 3-hydroxylase, CHI: chalcone isomerase, CHR: chalcone reductase, CHS: chalcone synthase, DFR: dihydroflavonol 4-reductase, FHT: flavanone 3-hydroxylase, F3′H: flavonoid 3′-hydroxylase, FNSII: flavone synthase II.</p

UV nectar guides.

<p><i>Bidens ferulifolia</i> flower UV photography of front (a) and back (e) side, daylight photographies (b, f) and after (c, g) ammonia staining. Cross sections of <i>B. ferulifolia</i> petals base native (i) and stained (j) and petal apex native (k) and stained (l). Epi-illumination mode microscopic view of stained epidermis of petal front side base (d) and apex (h). <i>Coreopsis grandiflora</i> flower before (m) and after (n) ammonia staining. <i>Cosmos sulphureus</i> flower before (o) and after (p) ammonia staining.</p