D-RADA16-RGD-Reinforced Nano-Hydroxyapatite/Polyamide 66 Ternary Biomaterial for Bone Formation

BACKGROUND: Nano-hydroxyapatite/polyamide 66 (nHA/PA66) is a composite used widely in the repair of bone defects. However, this material is insufficient bioactivity. In contrast, D-RADA16-RGD self-assembling peptide (D-RADA16-RGD sequence containing all D-amino acids is Ac-RADARADARADARADARGDS-CONH2) shows admirable bioactivity for both cell culture and bone regeneration. Here, we describe the fabrication of a favorable biomaterial material (nHA/PA66/D-RADA16-RGD). METHODS: Proteinase K and circular dichroism spectroscopy were employed to test the stability and secondary structural properties of peptide D-RADA16-RGD respectively. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to characterize the surface of these materials. Confocal laser scanning (CLS), cell counting kit-8 tests (CCK-8), alizarin red S staining, cell immunofluorescence analysis and Western blotting were involved in vitro. Also biosafety and bioactivity of them have been evaluated in vivo. RESULTS: Proteinase K and circular dichroism spectroscopy demonstrated that D-RADA16-RGD in nHA/PA66 was able to form stable-sheet secondary structure. SEM and TEM showed that the D-RADA16-RGD material was 7–33 nm in width and 130–600 nm in length, and the interwoven pore size ranged from 40 to 200 nm. CLS suggests that cells in nHA/PA66/D-RADA16-RGD group were linked to adjacent cells with more actin filaments. CCK-8 analysis showed that nHA/PA66/D-RADA16-RGD revealed good biocompatibility. The results of Alizarin-red S staining and Western blotting as well as vivo osteogenesis suggest nHA/PA66/D-RADA16-RGD exhibits better bioactivity. CONCLUSION: This study demonstrates that our nHA/PA66/D-RADA16-RGD composite exhibits reasonable mechanical properties, biocompatibility and bioactivity with promotion of bone formation.

Preliminary study on spinal nerve coding and injury typing / 中华创伤杂志

Currently,there is no study on the unified coding of the spinal nerve and its main branches.The positions of spinal nerve were encoded according to the basic anatomical principles from top to bottom,from inside to outside and from front to back,with reference to AO bone classification and somatic artery coding and injury classification system.The segmental coding of spinal nerves was decided by its branches and running characteristics.The spinal nerve injuries were encoded by a combination of numbers and letters.The first number represented the region,the second represented the injured nerve,and the third represented the specific segment of injured nerve.The injuries of spinal nerve were divided into 5 categories according to severity.The first letter indicated the category of injury,and the second indicated the orientation of the injured nerve.The functional score scale of the innervation area was prepared based on the evaluation of motor function,sensory function and the results of neurophysiological examination.This scale was used to classify the neurological injuries,guide the clinical treatment and evaluate the prognostic outcomes.This coding and classification system can clearly and comprehensively describe the location and type of spinal nerve injuries,and it is convenient for the diagnosis of nervous system damage.It also has important reference value for treatment and prognosis evaluation.