Multifunctional Delivery Nanosystems Formed by Degradable Antibacterial Poly(Aspartic Acid) Derivatives for Infected Skin Defect Therapy.

Nucleic acid (NA)-based therapy is promising for tissue repair, such as skin and bone defect therapy. However, bacterial infections often occur in the process of tissue healing. The ideal treatment of tissue repair requires both anti-infection and simultaneous tissue healing. The epidermal growth factor (EGF) plays an important role in wound healing processes. In this work, degradable antibacterial gene vectors based on tobramycin (clinically relevant antibiotic) conjugated poly(aspartic acid) (TPT) are proposed as multifunctional delivery nanosystems of plasmid encoding EGF (pEGF) to realize the antibacterial therapy and tissue healing of infected skin defects. TPT has low cytotoxicity and good degradability, which is helpful in the NA delivery process. TPT demonstrates good transfection performances and hemocompatibility, as well as excellent antibacterial activities in vitro. The outstanding pEGF delivery ability of TPT and the bioactivity of expressed EGF facilitate the proliferation of fibroblast cells. The effective in vivo infected skin defect therapy is also demonstrated with TPT/pEGF nanocomplexes, where skin tissue healing is promoted. The present work opens new avenues for the design of multifunctional delivery nanosystems with antibacterial ability to treat infected tissue defect.

Mechanical Properties of Orthodontic Thermoplastics PETG/ PC2858 after Blending.

OBJECTIVE: To characterise and compare the tensile characteristics after multi-proportional blending, to determine the proper blending ratio for new thermoplastic material and to compare its mechanical performance with commercial thermoplastics. METHODS: PETG and PC2858 aggregates were blended in five different ratios. Standard specimens of each ratio were molded and tested to determine their mechanical performance. Then the new material with the proper blending ratio was chosen and compared against commercial thermoplastics. RESULTS: With the increase of PC2858 content, the tensile and impact strength increased but elongation at break decreased. When blending ratio (wt %) was 70/30, the PETG/PC2858 exhibited optimal mechanical properties, with a tensile strength of 63.42 ± 1.67 MPa, and a stress relaxation rate of 0.0080 ± 0.0005 N/s, which exceeded those of Erkodur and Biolon. CONCLUSION: By blending PETG and PC2858 at the weight ratio 70/30, we obtained new thermoplastic material which outperformed commercial products.

[A comparative study of mechanical properties of commercialized dental thermoplastic materials].

OBJECTIVE: To compare the mechanical properties of different dental optimal material selection for orthodontic appliance. METHODS: Four commercialized thermoplastic products under different test conditions, and provide the suggestion of thermoplastic products were tested. The tear strength, elongation at break and stress relaxation of these materials were measured under different test conditions. RESULTS: The tear strength declined after thermoforming, and rose again after 2 weeks of distilled water immersion. The elongation at break rose after thermoforming, and declined after 2 weeks of distilled water immersion. No significant changes were observed for brand A under different test conditions. Brand A showed the slowest stress relaxation of 0.0148 N/s. CONCLUSIONS: The mechanical properties of thermoplastic materials were influenced by environmental factors. Brand A exhibited optimal comprehensive properties.