Comparative microstructural study on the teeth of Mesozoic birds and non-avian dinosaurs.

Although it is commonly considered that, in birds, there is a trend towards reduced dentition, teeth persisted in birds for 90 Ma and numerous macroscopic morphologies are observed. However, the extent to which the microstructure of bird teeth differs from other lineages is poorly understood. To explore the microstructural differences of the teeth of birds in comparison with closely related non-avialan dinosaurs, the enamel and dentine-related features were evaluated in four Mesozoic paravian species from the Yanliao and Jehol biotas. Different patterns of dentinal tubular tissues with mineralized extensions of the odontoblast processes were revealed through the examination of histological sectioning under electron microscopy. Secondary modification of the tubular structures, forming reactive sclerotic dentin of Longipteryx, and the mineralization of peritubular dentin of Sapeornis were observed in the mantle dentin region. The new observed features combined with other dentinal-associated ultrastructure suggest that the developmental mechanisms controlling dentin formation are quite plastic, permitting the evolution of unique morphologies associated with specialized feeding behaviours in the toothed birds. Proportionally greater functional stress placed on the stem bird teeth may have induced reactive dentin mineralization, which was observed more often within tubules of these taxa. This suggests modifications to the dentin to counteract potential failure.

Phenylboronic acid-modified polymaleic anhydride-F127 micelles for pH-activated targeting delivery of doxorubicin.

Phenylboronic acid (PBA) is a tumor-targeting molecule which selectively recognizes sialic acid (SA) overexpressed in tumors. In the study, PBA, F127 and ethanolamine were conjugated with poly(maleic anhydride) by one-step reaction to form amphiphilic polymer for doxorubicin encapsulation. Two drug-carrying micelles with different mass ratio of polymer to drug were prepared by dialysis method to study effect of PBA on doxorubicin release, tumor-targeting and antitumor activity. The study results showed that doxorubicin release from the formulations was acid-sensitive and affected by the polymer dosage, and its acid-induced release behavior improved its insertion into DNA base pairs. Formulation with high polymer dosage showed better tumor targeting and antitumor activity, and activity of inhibiting HepG2 with higher content of SA-containing glycosphingolipids was higher than that of anti-B16. In vivo studies on the activity of B16-bearing mice showed that the doxorubicin-loaded micelles could inhibit the tumor growth and were safer than free doxorubicin. Thus, the PBA-modified nano-polymer micelles have potential biomedical applications due to their nanostructure and tumor-targeting ability.

Azithromycin-loaded linolenic acid-modified methoxy poly(ethylene glycol) micelles for bacterial infection treatment.

In the study, new polymeric micelles loaded with azithromycin were prepared to enhance azithromycin's solubility and evaluate its in vitro/in vivo antibacterial activity against Staphylococcus aureus. Amphiphilic α-Linolenic acid-methoxy poly (ethylene glycol) polymer (MPEG-LNA) was synthesized through DCC-DMAP esterification procedure. Through thin-film hydration method, optimized azithromycin-loaded micelles (AZI-M) were prepared with 87.15% of encapsulation efficiency and 11.07% of drug loading capacity when the ratio of LNA to MPEG was 4. Azithromycin's water-solubility was obviously enhanced due to its loading into the polymeric micelles. The azithromycin-loaded micelles were characterized in terms of x-ray diffraction, Fourier transform infrared spectroscopy, in vitro release, and in vitro/in vivo antibacterial experiments. Although the drug-loaded micelles provided a slow and continuous azithromycin's release in comparison with free azithromycin, in vitro antibacterial activity results confirmed that its effect on the inhibition of bacterial growth and biofilm formation was similar to free azithromycin. It is more interesting that the azithromycin-loaded micelles achieved good in vivo antibacterial therapeutic effect like QiXian® (azithromycin lactobionate injection) in mouse model of intraperitoneal infection. AZI-M can be considered as a potential candidate for in vivo antibiotic therapy of Staphylococcus aureus infections.

Linolenic acid-modified MPEG-PEI micelles for encapsulation of amphotericin B.

Aim: To encapsulate amphotericin B (AmB) with reduced toxicity and comparable activity. Results & methodology: The α-linolenic acid (ALA)-modified monomethoxy polyethylene glycol-g-PEI-g-ALA conjugate was employed to prepare AmB-loaded micelles (AmB-M). In vitro activity and release behavior of AmB-M were investigated. AmB-M enhanced AmB's water-solubility to 1.2 mg/ml, showing good storage stability. AmB-M could achieve a sustained and slow release of AmB, low hemolysis activity and negligible kidney toxicity when compared with commercial AmB injection. Antifungal activity and biofilm inhibition experiments confirmed that the antifungal activity of AmB-M against Candida albicans was similar to that of AmB injection. Conclusion: Monomethoxy polyethylene glycol-g-PEI-g-ALA micelles could be a preferable choice to treat systemic fungal infections as an efficient drug delivery system.

Linolenic acid-modified methoxy poly (ethylene glycol)-oligochitosan conjugate micelles for encapsulation of amphotericin B.

Introduction of linolenic acid (LNA) and methoxy poly (ethylene glycol) (MPEG) to the backbone of oligochitosan (CS) afforded LNA-modified MPEG-CS conjugate (MPEG-CS-LNA). Amphotericin B-loaded MPEG-CS-LNA micelles (AmB-M) were prepared via dialysis method with 82.27 ± 1.96% of drug encapsulation efficiency and 10.52 ± 0.22% of drug loading capacity. The AmB-M enhanced AmB's water-solubility to 1.64 mg/mL, being 1640-folds higher than native AmB. The AmB-M obviously reduced hemolytic effect and renal toxicity of AmB when compared to marketed AmB injection (AmB-I). Its antifungal activity against Candida albicans was equivalent to AmB-I although AmB's release from AmB-M was significantly retarded. According to fluorescence microscopy test, the unchanged activity should be attributed to enhanced fungal cellular uptake of AmB-M caused by combined inducement of LNA and CS. The pharmacokinetic studies demonstrated that AmB-M also improved the pharmacokinetic parameters of AmB with AmB-I as control. Conclusively, developed LNA-modified MPEG-CS micellar system could be a viable alternative to the current toxic commercial AmB-I as a highly efficacious drug delivery system.

Oligochitosan-pluronic 127 conjugate for delivery of honokiol.

Honokiol-loaded micelles were prepared by emulsion-solvent evaporation procedure when oligochitosan-pluronic conjugate (CS-F127) as carrier. Differential scanning calorimetry (DSC) indicated that honokiol existed in amorphous form when it was encapsulated into the micelles with 87.54 ± 1.52% of encapsulation efficiency (EE) and 12.51 ± 0.22% of drug loading (DL) capacity. The water-solubility was increased to 1.46 mg/mL, being >27-folds higher than pure honokiol. The in vitro release study demonstrated a slow and sustained ± release of honokiol from the drug-loaded micelles with pure honokiol as control. The in vitro antifungal and cellular uptake tests indicated that the drug-loaded micelles showed the same activity as pure honokiol against Candida albicans due to its good cellular uptake although it slowly released honokiol. The pharmacokinetic test results showed that the honokiol-loaded micelles increased area under curves and mean retention time of honokiol with low clearance rate and apparent distribution volume when compared with pure honokiol, showing its ability to improve honokiol's pharmacokinetic properties. The honokiol-loaded micelles also showed good bio-security to normal cells and main organs of mice. In conclusion, the CS-F127 conjugate should be a potential carrier for honokiol or other antifungal agents in the treatment of fungal infections.

Recent Progress of Nano-drug Delivery System for Liver Cancer Treatment.

Liver cancer is one of serious diseases which threaten human life and health. Studies on the treatment of liver cancer have attracted widespread attention. Application of nano-drug delivery system (NDDS) can not only improve selective drug delivery to liver tissue and improve the bioavailability of drug, but also can reduce the side effects of drugs when it is specially modified in the respects of structure modification or specific target molecules decoration. This review will address the latest development of liver-targeted drug delivery system.

High diversity of the Ganzhou Oviraptorid Fauna increased by a new "cassowary-like" crested species.

A new oviraptorid dinosaur from the Late Cretaceous of Ganzhou, bringing oviraptrotid diversity of this region to seven taxa, is described. It is characterized by a distinct cassowary-like crest on the skull, no pleurocoels on the centra from the second through fourth cervical vertebrae, a neck twice as long as the dorsal vertebral column and slightly longer than the forelimb (including the manus). Phylogenetic analysis recovers the new oviraptorid taxon, Corythoraptor jacobsi, as closely related to Huanansaurus from Ganzhou. Osteochronology suggests that the type specimen of Corythoraptor had not reached stationary growth stage but died while decreasing growth rates. The histology implies that it would correspond to an immature individual approximately eight years old. We hypothesize, based on the inner structure compared to that in modern cassowaries, that the prominent casque of Corythoraptor was a multifunction-structure utilized in display, communication and probably expression of the fitness during mating seasons.

Y-shaped methoxy poly (ethylene glycol)-block-poly (epsilon-caprolactone)-based micelles for skin delivery of ketoconazole: in vitro study and in vivo evaluation.

Ketoconazole is a hydrophobic broad-spectrum antifungal agent for skin infection therapy. In order to develop topical formulation of ketoconazole for improving its selective skin deposition and water-solubility, ketoconazole-loaded Y-shaped monomethoxy poly(ethylene glycol)-block-poly(ɛ-caprolactone) micelles were prepared through thin-film hydration method with high entrapment efficiency (96.1±0.76%) and small particle (about 58.66nm). The drug-loaded micelles showed comparative in vitro antimicrobial activity with KET cream. In ex in vivo skin deposition and permeation study, ketoconazole-loaded micelles provided skin accumulation higher than marketed ketoconazole cream without obvious permeation in the whole period. Fluorescence microscopy study and histopathological study demonstrated the copolymeric micelles' penetrating into skin in depth due to its capability of weakening the barrier function of stratum corneum. In vivo skin deposition parameters further confirmed high skin deposition of drug-loaded micelles (AUC(0-t)=396.16µg·h/cm2) over marketed ketoconazole cream (AUC(0-t)=250.03µg·h/cm2). Meanwhile, in vivo pharmacokinetic parameters proved that ketoconazole-loaded micelles reduced ketoconazole's distribution in blood in comparison with the cream (AUC(0-t)=93,028.00µg·h/L vs AUC(0-t)=151,714.00µg·h/L), meaning lower possibility of its systemic unwanted effects in the skin fungal infection treatment. The results suggested that the copolymeric micelles can be adopted for specific delivering ketoconazole into skin for fungal infection cure.

In vitro characterization of pH-sensitive azithromycin-loaded methoxy poly (ethylene glycol)-block-poly (aspartic acid-graft-imidazole) micelles.

In order to improve azithromycin's antibacterial activity in acidic medium, monomethoxy poly (ethylene glycol)-block-poly (aspartic acid-graft-imidazole) copolymer was synthesized through allylation, free radical addition, ring-opening polymerization and amidation reactions with methoxy poly (ethylene glycol) as raw material. Drug loading capacity and encapsulation efficiency of azithromycin-loaded micelles prepared via thin film hydration method were 11.58±0.86% and 96.06±1.93%, respectively. The drug-loaded micelles showed pH-dependent property in the respects of particle size, zeta potential at the range of pH 5.5-7.8. It could control drug in vitro release and demonstrate higher release rate at pH 6.0 than that at pH 7.4. In vitro antibacterial experiment indicated that the activity of azithromycin-loaded micelles against S. aureus was superior to free azithromycin in medium at both pH 6.0 and pH 7.4. Using fluorescein as substitute with pH-dependent fluorescence decrease property, laser confocal fluorescence microscopy analysis confirmed that cellular uptake of micelles was improved due to protonation of copolymer's imidazole groups at pH 6.0. The enhanced cellular uptake and release of drug caused its activity enhancement in acidic medium when compared with free drug. The micellar drug delivery system should be potential application in the field of bacterial infection treatment.

Enhanced effect in combination of curcumin- and ketoconazole-loaded methoxy poly (ethylene glycol)-poly (ε-caprolactone) micelles.

In order to enhance water-solubility and realize controlled release while keeping synergistic effects of ketoconazole and curcumin, drug-loaded methoxy poly (ethylene glycol)-b-poly (ε-caprolactone) micelles were prepared through thin membrane hydration method. Transmission electric microscopy and dynamitic light scattering characterization revealed the formation of ketoconazole- and curcumin-loaded micelles with an average size of 44.70nm and 39.56nm, respectively. The drug-loaded micelles endowed the two drugs' slow controlled release with water-solubility enhanced to 85 and 82000 folds higher than the corresponding raw drugs, respectively. In vitro antifungal activity test, chequerboard test and inhibition zone test indicated that efficacy of ketoconazole-loaded micelles was improved by introduction of curcumin-loaded micelles with a low fractional inhibitory concentration index (0.073). Biofilm formation inhibition assay also demonstrated that participation of curcumin-loaded micelles obviously strengthened the inhibition of fungal biofilms formation induced by ketoconazole-loaded micelles. The high synergistic activity of combinations is encouraging and the MPEG-PCL micelle is a potential drug delivery system for the combination of ketoconazole and curcumin.

Y-shaped Folic Acid-Conjugated PEG-PCL Copolymeric Micelles for Delivery of Curcumin.

BACKGROUND: Curcumin is a natural hydrophobic product showing anticancer activity. Many studies show its potential use in the field of cancer treatment due to its safety and efficiency. However, its application is limited due to its low water-solubility and poor selective delivery to cancer. OBJECTIVE: A Y-shaped folic acid-modified poly (ethylene glycol)-b-poly (ε-caprolactone)2 copolymer was prepared to improve curcumin solubility and realize its selective delivery to cancer. METHOD AND RESULTS: The copolymer was synthesized through selective acylation reaction of folic acid with α- monoamino poly(ethylene glycol)-b-poly(ε-caprolactone)2. Curcumin was encapsulated into the copolymeric micelles with 93.71% of encapsulation efficiency and 11.94 % of loading capacity. The results from confocal microscopy and cellular uptake tests showed that folic acid-modified copolymeric micelles could improve cellular uptake of curcumin in Hela and HepG2 cells compared with folic acid-unmodified micelles. In vitro cytotoxicity assay showed that folic acid-modified micelles improved anticancer activity against Hela and HepG2 cells in comparison to folic acidunmodified micelles. Meanwhile, both drug-loaded micelles demonstrated higher activity against Hela cell lines than HepG2. CONCLUSION: The research results suggested that the folic acid-modified Y-shaped copolymeric micelles should be used to enhance hydrophobic anticancer drugs' solubility and their specific delivery to folic acid receptors-overexpressed cancer.

Methoxy poly (ethylene glycol)-b-poly (δ-valerolactone) copolymeric micelles for improved skin delivery of ketoconazole.

Ketoconazole is a broad spectrum imidazole antifungal drug. For the treatment of superficial fungal infections with ketoconazole, it needs to be permeated to deep skin layers. In order to develop topical formulation of ketoconazole for improving its skin deposition and water-solubility, ketoconazole-loaded methoxy poly (ethylene glycol)-b-poly (δ-valerolactone) micelles were developed through thin-film hydration method. Particle size, drug loading capacity, infrared spectrum and X-ray diffraction of drug-loaded micelles were characterized. The optimal drug formulation was selected for skin delivery and deposition investigation performed by use of mice skin, and its in vitro release and antifungal activity were also investigated. Penetration and distribution in the skin were also visualized using fluorescein-loaded micelles and fluorescence microscopy. The drug-loaded micelles were obtained with encapsulation efficiency of 86.39% and particle diameter of about 12 nm. The micelles made ketoconazole aqueous solubility increase to 86-fold higher than crude one. Ketoconazole-loaded micelles showed no skin permeation of ketoconazole, obviously enhance skin deposition and demonstrated similar antifungal activity as compared with marketed ketoconazole cream. Fluorescein-loaded micelles displayed higher skin deposition than fluorescein water solution. These results demonstrate that the MPEG-PVL micelle is a potential delivery system for ketoconazole in the field of skin delivery.

Development on PEG-modified Poly (Amino Acid) Copolymeric Micelles for Delivery of Anticancer Drug.

BACKGROUND: Polymeric micelles can provide a valid way for cancer treatment with several benefits including high water-solubility of lipophilic drugs, low unwanted effects of cytotoxic drugs by way of reduced systemic exposure and prolonged retention time in the circulatory system. OBJECTIVE: Recently, there is an increasing interest in preparing poly (ethylene glycol)-poly (amino acid) copolymeric micelles as drug delivery carriers due to their multifunctional property, easy decoration and biosafety. The copolymer contains several functional groups, which show stronger interactions with drugs or can be transferred to develop different types of the copolymers showing pH-, reduction-, thermo-sensitive, targeted or double-function properties. In addition, conjugation of drugs with these copolymers also becomes a novel modification method with the aim of higher drug loading capacity and stability. Copolymeric micelles show exciting advantages on improving a drug's water-solubility, release behavior, in vitro activity, targeted delivery pharmacokinetic property and biodistribution. In this review, we will introduce the recent development of poly(ethylene glycol)-modified poly (amino acid) copolymeric micelles as anticancer drug delivery systems containing different stimuli (such as thermo-, pH-, reduction- or special enzyme- condition) functional groups and targeting ligands to improve cellular uptake or biostablility of drug-loaded micelles. CONCLUSION: Poly (ethylene glycol)-poly (amino acid) copolymeric micelles provide an opportunity to realize anticancer drug delivery with environment-responsive and/or targeting property.

Recent Development of Copolymeric Delivery System for Anticancer Agents Based on Cyclodextrin Derivatives.

Core-shell structured aggregates of amphiphilic block copolymer are hopefully drug delivery system because of their ability to encapsulate hydrophobic drugs, and their hydrophilic shell can prolong retention time of drugs in the blood circulation system. Cyclodextrin is a kind of hydrophilic polysaccharide containing multiple hydroxyl groups, providing an inner hole that can load small molecule through host-guest interaction. These hydroxyl groups or their derived functional ones are utilized in conjugation with polymeric chains to form block copolymers. These copolymers can not only encapsulate hydrophobic drugs, but also encapsulate hydrophilic drugs (like DNA, protein, etc) through hydrophobic, host-guest or electrostatic interactions, which strengthen interaction between drugs and materials compared with general copolymers, indicating that formed drug delivery systems are more stable. By introduction of target molecule, they also achieve selective delivery of drugs to specific tissues or organs. So, several researchers are stimulated to carry out many studies for the development of cyclodextrin copolymeric drug delivery systems in recent. In this review, we focus the cyclodextrin copolymers' application in the anticancer agents' delivery.

Poly(ethylene glycol) amphiphilic copolymer for anticancer drugs delivery.

Poly(ethylene glycol) is a water-soluble polymer. Due to its high safety and biocompatibility, it has been widely used to prepare amphiphilic copolymers for drug delivery. These copolymers can enhance water-solubility of hydrophobic drugs, improve their pharmacokinetic parameters and control their release from corresponding nanocarriers formed by its self-assembly. Anticancer drugs have some shortcomings such as lower water-solubility, bad targeting and some serious side-effects, which limit their applications and are dangerous to patients. So encapsulation of anticancer drugs into nanocarriers originated from its copolymeric derivates can improve their absorption, distribution, metabolism and excretion with better release properties and activities against cancer cells, increase their therapeutic effects, and realize their passive or active target delivery through structure modification. Recent research development of its drug delivery systems for anticancer drugs will be discussed.

Y-shaped biotin-conjugated poly (ethylene glycol)-poly (epsilon-caprolactone) copolymer for the targeted delivery of curcumin.

In order to improve curcumin's low water-solubility and selective delivery to cancer, we reported ligand-mediated micelles based on a Y-shaped biotin-poly (ethylene glycol)-poly (epsilon-caprolactone)2 (biotin-PEG-PCL2) copolymer. Its structure was characterized by (1)H NMR. The blank and drug-loaded micelles obtained by way of thin-film hydration were characterized by dynamic light scattering, X-ray diffraction, infrared spectroscopy and hemolytic test. Curcumin was loaded into micelles with a high encapsulating efficiency (93.83%). Curcumin's water-solubility was enhanced 170,400 times higher than free curcumin. Biotin-PEG-PCL2 micelles showed slower drug release in vitro than H2N-PEG-PCL2 micelles. In vitro cellular uptake and cytotoxicity tests showed that higher dosage of curcumin might overcome the effect of slow release on cytotoxicities because of its higher uptake induced by biotin, resulting in higher anticancer activities against MDA-MB-436 cells. In brief, Y-shaped biotin-PEG-PCL2 is a promising delivery carrier for anticancer drug.