Hydroxyl silicone oil grafting onto a rough thermoplastic polyurethane surface created durable super-hydrophobicity.

Indwelling medical catheters are frequently utilized in medical procedures, but they are highly susceptible to infection, posing a vital challenge for both health workers and patients. In this study, the superhydrophobic micro-nanostructure surface was constructed on the surface of thermoplastic polyurethane (TPU) membrane using heavy calcium carbonate (CaCO3) template. To decrease the surface free energy, hydroxyl silicone oil was grafted onto the surface, forming a super-hydrophobic surface. The water contact angle (WCA) increased from 91.1° to 143 ± 3° when the concentration of heavy calcium CaCO3 was 20% (weight-to-volume (w/v)). However, the increased WCA was unstable and tended to decrease over time. After grafting hydroxyl silicone oil, the WCA rose to 152.05 ± 1.62° and remained consistently high for a period of 30 min. Attenuated total reflection infrared spectroscopy (ATR-FTIR) analysis revealed a chemical crosslinking between silicone oil and the surface of TPU. Furthermore, Scanning electron microscope (SEM) image showed the presence of numerous nanoparticles on the micro surface. Atomic force microscope (AFM) testing indicated a significant improvement in surface roughness. This method of creating a hydrophobic surface demonstrated several advantages, including resistance to cell, bacterial, protein, and platelet adhesion and good biosecurity. Therefore, it holds promising potential for application in the development of TPU-based medical catheters with antibacterial properties.

Surface grafting of sericin onto thermoplastic polyurethanes to improve cell adhesion and function.

Thermoplastic polyurethane (TPU) membrane has super physical-mechanical properties and biocompatibility, but the surface is inert and lack of active groups which limit its application in cell culture. Silk sericin (SS) can improve cell adhesion, proliferation, growth and metabolism. In this paper, SS was grafted onto the surface of TPU membrane by -NH2 bridge to build a high efficiency cell culture membrane. The FT-IR spectrum results indicated SS was grafted by chemical bond. According to the SEM and AFM results, we found that the grafting of SS reduced the water contact angle by 43.31% and increased the surface roughness by about four times. When TPU-SS was used for HepG2 cell culture, the cell adhesion rate of TPU-SS was significantly higher than that of the general TCPS cell culture plate, and the cell proliferation rate was close to that of TCPS. FDA/EB staining showed that HepG2 cells remained a better cellular growth behavior. HepG2 cells had higher cell vitality including the albumin secretion and the intracellular total protein synthesis. Grafting SS maintained the stability of cell and significantly decreased the cytotoxicity by decreased LDH release. In conclusion, SS grafting is beneficial to cell culture in vitro, and provides a key material for bioartificial liver culture system.

Sericin-reinforced dual-crosslinked hydrogel for cartilage defect repair.

Articular cartilage is essential for normal daily joint function activities. However, it is difficult for articular cartilage to repair itself after injury due to the lack of nerves and blood vessels, so an effective cartilage repair method is necessary. As a three-dimensional polymer network structure with high water content, hydrogel is a good candidate material for cartilage repair, and it is also a research hotspot in the treatment of cartilage injury. Here, a porous dual-crosslinked hydrogel containing sodium alginate (SA) and silk sericin (SS) was designed for in situ repair of cartilage damage. The degradation rate of the hydrogel was regulated by changing the content of SS to match the rate of cartilage regeneration. The hydrogel had excellent mechanical properties (compressive strength≈245 kPa, compressibility≈60%), high water content (85%-88%) and porosity(>20%), and when the content of SS is 1%, the scaffold has the best comprehensive performance. Existing excellent cytocompatibility, the scaffold can promote the adhesion and proliferation of chondrocytes while reducing inflammatory cell infiltration. The cartilage defect repair experiments in vivo showed that artificial cartilage was formed at 4 weeks with molecular structure similar to natural cartilage. It is expected to be applied to clinical cartilage repair through the dual-crosslinked three-dimensional cartilage scaffold.

Enhanced physical and biological properties of chitosan scaffold by silk proteins cross-linking.

To improve the application of chitosan (CS)-based scaffold for tissue regeneration, in this study, silk sericin (SS) and silk fibroin (SF) were employed to strengthen the cross-linking of the CS/glycerophosphate (GP) scaffolds. The CS/GP, SS/CS/GP and SF/SS/CS/GP scaffolds were fabricated by collosol-gelling and freeze-drying. The SS and SF improved the physical cross-linking of CS/GP scaffolds, formed uniform layered structures, increased mechanical properties, and decreased degradation velocity. Silk proteins significantly promoted cell growth into the scaffold and increased the blood compatibility. When the SF/SS/CS/GP scaffold was implanted into SD rats, appeared an initial acute inflammatory response, host cells invaded, new muscle fibers grow and formed. And no systemic acute toxicity was observed. The findings demonstrated that silk proteins could enhance the physical and biological properties of chitosan scaffold.

Preparation and characterization of gelatin/sericin/carboxymethyl chitosan medical tissue glue.

BACKGROUND: The development and application of medical glue has been continuously expanding and advancing. However, there are few glues that combine low-cost with excellent biocompatibility. METHODS: We have prepared a medical tissue glue using a gelatin (Gel), sericin (SS) and carboxymethyl chitosan (CMCS) blend solution, cross-linked with 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC). The combination's characteristics and microstructure morphology were observed by Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscope (SEM). Bond strength tests were used to measure the bond strength of the glue. To assay blood compatibility, a hemolytic test, dynamic coagulation test and platelet adherence test were also investigated. Further, the cellular behavior of L-929 and a systemic acute toxicity test on the Gel/SS/CMCS tissue glue were also investigated by MTT and H&E staining. RESULTS: Characterization analysis showed that there was stable binding between raw materials, forming an amide bond with homogeneous holes. The bond strength of the tissue glue reached 2.50 ± 0.04 N in 10 minutes, slightly higher than the alpha-cyanoacrylate biological glue (2.25 ± 0.05 N). Blood compatibility tests revealed that the glue had outstanding blood compatibility. Further, cytotoxicity test and systemic acute toxicity test both showed that the glue was without cytotoxicity and not toxic to the body. CONCLUSIONS: The Gel/SS/CMCS tissue glue we prepared at low cost had excellent biocompatibility and structural characteristics. It could be a better candidate for tissue engineering in biomedical applications applied in clinical practice to promote skin wound healing and to further reduce the formation of skin wound scars.

Formation characterization of hydroxyapatite on titanium by microarc oxidation and hydrothermal treatment.

Microarc oxidation (MAO) was performed on titanium in an electrolyte containing calcium glycerphosphate (Ca-GP) and calcium acetate (CA) using a direct current power supply. It was found that the MAO method is suitable forming a ceramic coating containing Ca and P using titanium, and that films display a porous and rough structure on their surface. Samples with a Ca/P ratio of 1.71 were hydrothermally treated in water solution whose pH was adjusted to 7.0-11.0 by adding NaOH at 190 degrees C for 10 h in an autoclave. Hydroxyapatite crystals were precipitated on the film surface after the hydrothermal treatment, and the amount of hydroxyapatite precipitated increased with increasing pH of water solution. The oxide film composition was semiquantitatively analyzed with an electron probe microanalyzer. The microstructures on the sample surfaces were observed by scanning electron microscopy before and after the hydrothermal treatment. The topography of the oxide film was imaged with an atomic force microscope. Its cross section was observed by scanning electron microscopy after being coated with a thin Au film. The surface structures of the films were analyzed by X-ray diffraction.

The formation mechanism of the beta-TCP phase in synthetic fluorohydroxyapatite with different fluorine contents.

Synthetic hydroxyapatite (HAP) and fluorohydroxyapatite (F(x)AP) products may form the beta-tricalcium phosphate (beta-TCP) phase in a calcination process. The beta-TCP phase has a greater tendency for degradation in vivo than HAP and F(x)AP. Hence, controlling the content of the beta-TCP phase in the apatite is a pivotal factor to affect their lifetime and stability in vivo. It is particularly important to explore the formation mechanism of the beta-TCP phase in synthetic apatite. In this work, F(x)AP products with a chemical composition of Ca(10)(PO(4))(6)(OH)(2-x)F(x) are synthesized, with x = 0, 0.4, 0.8, 1.2, 1.6 and 2.0, using a precipitation method and a calcination process. The effect of fluorine substitution for hydroxyl is investigated by using x-ray diffraction analysis, Fourier transform infrared spectroscopy, and thermogravimetry and differential thermal analysis. The results show that addition of fluorine forms F(x)AP that exhibits high thermal stability. The beta-TCP phase produced as a result of the structural refinement by heat treatment is gradually reduced and dramatically suppressed with the fluorine content.