The healing effect of unrestricted somatic stem cells loaded in collagen-modified nanofibrous PHBV scaffold on full-thickness skin defects

Unrestricted somatic stem cells (USSCs) loaded in nanofibrous PHBV scaffold can be used for skin regeneration when grafted into full-thickness skin defects of rats. Nanofibrous PHBV scaffolds were designed using electrospinning method and then, modified with the immobilized collagen via the plasma method. Afterward, the scaffolds were evaluated using scanning electron microscopy, physical and mechanical assays. In this study; nanofibrous PHBV scaffolds loaded with and without USSCs were grafted into the skin defects. The wounds were subsequently investigated at 21 days after grafting. Results of mechanical and physical analyses showed good resilience and compliance to movement as a skin graft. In animal models; all study groups excluding the control group exhibited the most pronounced effect on wound closure, with the statistically significant improvement in wound healing being seen on post-operative Day 21. Histological and immunostaining examinations of healed wounds from all groups, especially the groups treated with stem cells, showed a thin epidermis plus recovered skin appendages in the dermal layer. Thus, the graft of collagen-coated nanofibrous PHBV scaffold loaded with USSC showed better results during the healing process of skin defects in rat model.

Effect of the mechanical activation on size reduction of crystalline acetaminophen drug particles

The decrease in particle size may offer new properties to drugs. In this study, we investigated the size reduction influence of the acetaminophen (C₈H₉O₂N) particles by mechanical activation using a dry ball mill. The activated samples with the average size of 1 μm were then investigated in different time periods with the infrared (IR), inductively coupled plasma (ICP), atomic force microscopy (AFM), and X-ray diffraction (XRD) methods. The results of the IR and XRD images showed no change in the drug structure after the mechanical activation of all samples. With the peak height at full width at half maximum from XRD and the Scherrer equation, the size of the activated crystallite samples illustrated that the AFM images were in sound agreement with the Scherrer equation. According to the peaks of the AFM images, the average size of the particles in 30 hours of activation was 24 nm with a normal particle distribution. The ICP analysis demonstrated the presence of tungsten carbide particle impurities after activation from the powder sample impacting with the ball and jar. The greatest reduction in size was after milling for 30 hours.