Biodegradation of Silk Biomaterials

Silk fibroin from the silkworm, Bombyx mori, has excellent properties such as biocompatibility, biodegradation, non-toxicity, adsorption properties, etc. As a kind of ideal biomaterial, silk fibroin has been widely used since it was first utilized for sutures a long time ago. The degradation behavior of silk biomaterials is obviously important for medical applications. This article will focus on silk-based biomaterials and review the degradation behaviors of silk materials

In-vitro Antitumor Activity and Antifungal Activity of Pennogenin Steroidal Saponins from paris Polyphylla var. yunnanensis

Abstract Paris polyphylla Smith var. yunnanensis, has been used in traditional Chinese medicine cancer in particular. In this current study, -ecdysterone (1) and three pennogenin steroidal saponins (2-4) were isolated from the EtOH extract of Paris polyphylla var. yunnanensis, and their structures. Their antitumor properties were determined by using an MTT assay in addition to ethidium bromide and acridine orange staining techniques. -1 , respectively. The analysis of the bioactivity-structure relationship shows that the sugar moiety plays a critical role in the activity of steroid moiety. Our results suggest that these three pennogenin steroidal saponins could be utilized to develop anticancer medicines

Development of feather keratin nanoparticles and investigation of their hemostatic efficacy

Chicken feathers are considered as the major waste in poultry industry, which are mostly constituted of keratin proteins. Development of feather keratin for biomedical application is very attractive for chicken feather recycling. Human hair keratins have been demonstrated the significant hemostatic efficacy in the previous studies, but there are few reports of feather keratin for the hemostatic application. Here, the chicken feather keratin nanoparticle was developed for use as a hemostatic agent. Keratin was extracted from chicken feather in the present study, and a modified ultrasonic dispersion method was used to prepare keratin nanoparticles. The characterizations of feather keratin extracts and nanoparticles were investigated, including electrophoretic separation, amino acid composition, particle size, zeta potential, morphology, chemical structure and crystal form. Additionally, the hemostatic efficacy in vitro and in vivo of keratin nanoparticles were also studied. The results of hemostatic tests showed that the bleeding time and blood loss in tail amputation and liver scratch rat models can be significantly decreased after application of feather keratin nanoparticles, which demonstrated the potential application of feather keratin nanoparticles for hemostasis

The characteristics of geophysical field and tectonic evolution in the Bransfield Strait

Having analyzed the data collected by our survey ship "Ocean IV" in the Bransfield Strait in 1991, we recognized that the geomorphology, gravity and magnetic anomalies trending NE direction along bandings. The sediments in the Bransfield Strait can be subdivided into two sequences: the first rifting sequence and the second rifting sequence. The basement was faulted into a half-graben in northwestern side of the Bransfield trough. Considering the crustal structure crossing the South Shetland Islands, the Bransfield Strait and the Antarctic Peninsula, we propose a two-phase rifting tectonic evolution model and a layered-shear model for the lithospheric deformation under the effects of extensional stress field

The Impact of Bilirubin on 7α- and 7β-Hydroxysteroid Dehydrogenases: Spectra and Docking Analysis

7α- and 7β-hydroxysteroid dehydrogenases (HSDHs) are enzymes that can catalyze the isomerization of hydroxyl groups at site seven of bile acids. In a previous study, we found that the activities of 7α- and 7β-HSDHs can be inhibited by bilirubin. In order to clarify the impact, the effects of bilirubin on enzymes were studied by kinetics, spectrum, and docking analysis. The relative activity of 7α-HSDH remained less than 40% under 1 mM bilirubin, and only 18% activity of 7β-HSDH kept in the same condition. Using taurochenodeoxycholic acid (TCDCA) as substrate, the Km of 7α-HSDH was up to 0.63 mM from 0.24 mM after binding with bilirubin and the Km of 7β-HSDH rose from 1.14 mM to 1.87 mM for the catalysis of tauroursodeoxycholic acid (TUDCA). The affinity of 7α- and 7β-HSDHs to substrates decreased with the effect of bilirubin. The binding of bilirubin with 7α- or 7β-HSDHs was analyzed by UV–vis, fluorescence, and circular dichroism (CD) spectroscopy. The results reflected that bilirubin caused a slight change in the secondary structure of 7α- or 7β-HSDHs, and the changes were correlated with the ratio of bilirubin to enzymes. Ten candidate molecular docking results were presented to reflect the binding of bilirubin with 7α- or 7β-HSDHs and to explore the inhibition mechanism. This research provides a more in-depth understanding of the effect of bilirubin on 7α- and 7β-HSDHs

The Application of Thermosensitive Nanocarriers in Controlled Drug Delivery

Thermosensitive nanocarriers as the “smart” drug delivery systems have shown tremendous promise in the field of controlled drug delivery due to their special property. Thermosensitive nanocarriers with long circulation properties can accumulate in the pathological sites by enhanced permeability and retention (EPR) effect or attach targeting ligands to the surface of the nanocarriers, and the drug release rates of these pharmaceutical nanocarriers can be adjusted in response to thermal variability of the environment. In this paper, we first discuss the classification of thermosensitive polymer according to their functional properties in thermosensitive nanocarriers. On the basis of this, our main purposes are focused on reviewing the characteristics of various thermosensitive nanocarriers including the strategies for their functionalization, thermosensitive behavior, or site-specific targeting. Furthermore, the paper discusses the current and future trends of the thermosensitive nanocarriers in controlled drug delivery