Star polymers show great promise for a range of applications, including drug delivery and advanced coatings. Their unique solution properties and high functionality also make them attractive building blocks for the preparation of nanostructured thin films. This article describes the preparation of a poly(acrylic acid) (PAA)based core cross-linked star (CCS) polymer by the "arm first" approach and its assembly into multilayered films by the layer-by-layer (LbL) method. Synthesis of the PAA star polyelectrolyte was achieved by preparing an acid protected polymer, poly(tert-butyl acrylate), by atom transfer radical polymerization and reacting it with a divinyl monomer (divinylbenzene), followed by deprotection. The PAA star polyelectrolyte displayed pH-responsive behavior in solution, as studied by dynamic light scattering, where a reversible size change was observed in response to pH changes. At pH 8-10, the acrylic acid segments are fully charged, adopting a more stretched conformation, and larger diameters (∼30 nm) were observed. When the pH decreases, and associated protonation of the acid segments occurs, the PAA chains adopt a more coiled conformation, and the diameters decrease to ∼23 nm at pH 2. The PAA star polymer was LbL assembled with poly(allylamine hydrochloride) (PAH) at different pH conditions to form pH-responsive multilayer films. The PAA star polymer/PAH multilayer films showed distinct morphology changes in response to post-treatment with different pH solutions. At pH 11, the star polymer adopted a stretched conformation and smoother films were obtained, whereas at pH 2, grain domains were visible and comparatively rougher films were formed.

Herbal medicines have recently been recognized as the second most common cause of drug-induced liver injury (DILI) in the United States. However, reliable methods to identify the DILI causality of some herbs, such as Heshouwu (dried root of Polygonum multiflorum), remain lacking. In this study, a total of 12 307 inpatients with liver dysfunction and 147 literature-reported cases of Heshouwu DILI were screened. A general algorithm indicated that only 22.5% (9/40) and 30.6% (45/147) of all hospitalization and literature case reports, respectively, demonstrate the high probability of DILI causality of Heshouwu. By contrast, 95% (19/20) of all cases prospectively investigated by pharmacognosy, phytochemistry, and metabolomic tests exhibited highly probable causality, including a patient who was previously incorrectly attributed and a case that was excluded from Heshouwu causality by pharmacognostic evidence. Toxin (heavy metals, pesticides, and mycotoxins) contamination was also excluded from Heshouwu DILI causality. The objectivity of these screening methods for Heshouwu DILI diagnosis addresses safety concerns regarding stilbene-containing herbal medicines and dietary supplements.

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A novel method of chiral ligand-exchange CE was developed with either L- or D-lysine (Lys) as a chiral ligand and zinc(II) as a central ion. This type of chiral complexes was explored for the first time to efficiently separate either individual pairs of or mixed aromatic amino acid enantiomers. Using a running buffer of 5 mM ammonium acetate, 100 mM boric acid, 3 mM ZnSO(4) x 7H(2)O and 6 mM L-Lys at pH 7.6, unlabeled D,L-tryptophan, D,L-phenylalanine, and D,L-tyrosine were well separated, giving a chiral resolution of up to 7.09. The best separation was obtained at a Lys-to-zinc ratio of 2:1, zinc concentration of 2-4 mM and running buffer pH 7.6. The buffer pH was determined to have a strong influence on resolution, while buffer composition and concentration impacted on both the resolution and peak shape. Boric acid with some ammonium acetate was an adoptable buffer system, and some additives like ethylene diamine tetraacetic acid capable of destroying the complex should be avoided. Fine-tuning of the chiral resolution and elution order was achieved by regulating the ratio of L-Lys to D-Lys; i.e. the resolution increased from zero to its highest value as the ratio ascended from 1:0 to 1:infinitive, and L-isomers eluted before or after D-isomers in excessive D- or L-Lys, respectively.

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Heshouwu (HSW), the dry roots of Polygonum multiflorum, a classical traditional Chinese medicine is used as a tonic for a wide range of conditions, particularly those associated with aging. However, it tends to be taken overdose or long term in these years, which has resulted in liver damage reported in many countries. In this study, the indicative roles of nine bile acids (BAs) were evaluated to offer potential biomarkers for HSW induced liver injury. Nine BAs including cholic acid (CA) and chenodeoxycholic acid (CDCA), taurocholic acid (TCA), glycocholic acid (GCA), glycochenodeoxycholic acid (GCDCA), deoxycholic acid (DCA), glycodeoxycholic acid (GDCA), ursodeoxycholic acid (UDCA), and hyodeoxycholic acid (HDCA) in rat bile and serum were detected by a developed LC-MS method after 42 days treatment. Partial least square-discriminate analysis (PLS-DA) was applied to evaluate the indicative roles of the nine BAs, and metabolism of the nine BAs was summarized. Significant change was observed for the concentrations of nine BAs in treatment groups compared with normal control; In the PLS-DA plots of nine BAs in bile, normal control and raw HSW groups were separately clustered and could be clearly distinguished, GDCA was selected as the distinguished components for raw HSW overdose treatment group. In the PLS-DA plots of nine BAs in serum, the normal control and raw HSW overdose treatment group were separately clustered and could be clearly distinguished, and HDCA was selected as the distinguished components for raw HSW overdose treatment group. The results indicated the perturbation of nine BAs was associated with HSW induced liver injury; GDCA in bile, as well as HDCA in serum could be selected as potential biomarkers for HSW induced liver injury; it also laid the foundation for the further search on the mechanisms of liver injury induced by HSW.

A facile chiral ligand-exchange capillary electrophoretic method has been explored for the enantioseparation and UV detection of dansyl-amino acids with Zn(II) L-arginine complex as a chiral selecting system. Successful enantioseparation of 17 pairs of amino acid enantiomers has been achieved with a buffer of 100 mM boric acid, 5 mM ammonium acetate, 3 mM ZnSO4 and 6 mM L-Arg at pH 8.0, of which 10 pairs were fully resolved with resolution in between 1.59 and 4.21. This new method was shown to be applicable to the separation of some mixed pairs of amino acids and to the quantitative analysis of some real samples such as rice vinegars, with a linear range between 0.8 and 150 microg/mL, correlation coefficient above 0.99 and recovery in between 90.1 and 112.4%. It was found that amino acids with low resistance side chain(s), low tendency to form intramolecular hydrogen bond or high tendency to form intermolecular hydrogen bonds are more easily enantioseparated than those with extra carboxyl and/or phenyl groups. By the use of the suggested buffer, the running pH should be selected at 7.4-9.0 to compromise the resolution and elution speed.

A surface plasmon-enhanced resonance light scattering method has been developed. The method features strong light scattering but very weak background, and after incorporating with selective sample extraction and ion-association complexation using rhodamine B and KI as reactants, it could selectively determine Cr(VI) in both of standard and real samples, reaching a limit of detection down to 20 nM which is about 40-fold as sensitive as flame atomic absorption spectrometry and 140-fold as sensitive as fluorescent spectroscopy. Its linear working range was found in between 40 and 320 nM, with a relative standard deviation of peak height at <3% (n = 5) and recovery between 94.8-104.9%. In theory, the method is applicable to the analysis of all substances able to produce or destroy I2.