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.

[Preparation of polyvinyl alcohol film inlaid with silk fibroin peptide nano-scale particles and evaluation of its function to promote cell growth].

Nano-scale particles of silk fibroin peptide (SFP) were prepared from discarded materials of cocoon or filature by dissolving and enzymolysis. Polyvinyl Alcohol films inlaid with silk fibroin peptide nano-scale particles (SFP in PVA) were prepared by blending nano-SFP and PVA in water according to different blending ratios. The films' characteristics and their promoting cell growth functions were investigated. Silk fibroin fiber was dissolved in 60% NaSCN solution, and was decomposed with alpha-Chymotrypsin, Trypsin and Neutral, respectively. The uniformity of size of SFP nano-particles prepared by Neutral was better and appeared about 80-150 nm. (SFP in PVA) films were characterized by infrared spectroscopy (IR) measurement which demonstrated the combination of SFP and PVA. Scanning electron microscopy revealed the PVA films already inlaid with SFP micro-segment. The surface and form stability in water of the (SFP in PVA) films with blending ratios of 10/90, 20/80, 30/70 and 40/60 were observed. And the results showed that SFP/PVA film with the blending ratio of 30/70 has smoother surface and better stability in water. The Chinese hamster ovary (CHO) cells were cultured, and the promoting cell growth function of (SFP in PVA) films was assessed by MTT colorimetric assay. These findings indicate that SFP/PVA (30/70) film has excellent function of promoting cell growth.

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.

Preparation and properties of nanometer silk fibroin peptide/polyvinyl alcohol blend films for cell growth.

Nanometer silk fibroin peptide (Nano-SFP) was prepared from silkworm cocoons through the process of dissolution, dialysis and enzymolysis. For comparison, silk fibroin was decomposed with α-chymotrypsin, trypsin and neutrase, respectively. From the SEM and particle size analysis results, the Nano-SFP prepared by neutrase was found to be the most desirable at about 50-200 nm. Nano-SFP/polyvinyl alcohol films (Nano-SFP/PVA) were prepared by blending Nano-SFP and PVA in water with different weight ratios of 10/90, 20/80, 30/70, and 40/60. The films were characterized by IR, SEM, TG, DSC and tensile strength test for investigating their structure, surface morphology, thermostability, and mechanical property. The results showed that Nano-SFP inserted in the PVA films with small linear particles, and Nano-SFP/PVA films exhibited smooth surface, good thermostability and tensile strength. The growth of Chinese hamster ovary (CHO) cells on films with and without Nano-SFP was investigated with MTT colorimetric assay to assess the films' ability to promote cell growth. It was observed that the Nano-SFP improved cell adhesion on the film surface, and the ability of promoting cell growth increased with the increasing content of Nano-SFP in the blend films. Nano-SFP/PVA film with the ratio of 30/70 was concluded to have the best properties.