Different lag-time of pulse-released nerve growth factor (NGF) from genipin-crosslinked gelatin within polycaprolactone (PCL) conduits was evaluated in large-gap peripheral nerve repair. In this study, 10% (w/v) gelatin was mixed with NGF, crosslinked with 0%, 0.1%, 0.5%, and 1% (w/v) genipin, and then sucked into the wall of PCL conduits. These controlled-release nerve conduits were named NCL (non-crosslink), LCL (low crosslink), MCL (medium crosslink), and HCL (high crosslink), respectively. The NGF releasing character showed four distinctive curves, including initial burst within 5 days, pulse releasing at 5–20 days, pulse releasing at 10–25 days, and steadily releasing. The bioactivity of the released NGF was shown by neurite outgrowth of PC12 cells after culturing in all groups. Finally, the controlled-release conduits were seeded with 9 × 10³ Schwann cells. Conduits were used to bridge a 15-mm rat sciatic nerve defect, and the results were compared with the isografts (control group). Eight weeks after implantation, morphological analysis revealed that LCL, MCL, and HCL groups were similar to autograft treatment in the numbers and area of myelinated axons. The LCL group, although insignificant, showed a trend to have the highest myelinated axon counts of the conduit-treated groups. Thus, comparing the different NGF release characteristics among NCL, MCL, and LCL groups, we concluded that a high concentration of NGF at 5–10 days in LCL groups is needed in bridging a 15-mm peripheral nerve injury.

Radiation-induced skin injury (RSI) is a frequent complication of radiotherapy. Severe cases affect the patient’s disease treatment and quality of life. The main purpose of this study is to examine the causative role of egg-yolk oil (EYO) in delayed radiation-induced skin injury, including impaired wound healing. Using polyvinyl pyrrolidone (PVP)-gelatin-chitosan (PGC) composite film as controlled release of egg-yolk oil (EYO) was studied in rats, which were used as a radiation-induced skin injury model. Different composition ratios were tested for their mechanical properties, moisture content, and degradation characteristics. The results showed that the PGC112 (w/w) substrate, which will hence be referred to as PGC, had the better properties. Further, the PGC was mixed with EYO (0.25% and 0.5%) to prepare the films (PGC/0.25EYO and PGC/0.5EYO, respectively). Furthermore, the mechanical and degradation properties and biocompatibility showed better results with PGC/0.5EYO. In animal studies, rats were irradiated with single-dose electron beams of 40 Gy. The animals were divided into five groups to perform wound treatment with various types of wound dressing for 30 days. Histological examination and CD68 immunochemical staining were then conducted, and observations were made. The results showed that PGC/0.5EYO has a significantly healing effects on radiodermatitis and good re-epithelialization.

Magnetic nanoparticles are used to enhance the image contrast of magnetic resonance imaging (MRI). However, the development of magnetic nanoparticles with a low dose/high image contrast and non-toxicity is currently a major challenge. In this study, cobalt-substituted hydroxyapatite nanoparticles deposited on titanium (Ti-CoHA) and cobalt-substituted hydroxyapatite nanoparticles deposited on titanium dioxide nanotubes (TNT-CoHA) were synthesized by the electrochemical deposition method. The particle sizes of Ti-CoHA and TNT-CoHA were 418.6 nm and 127.5 nm, respectively, as observed using FE-SEM. It was shown that CoHA can be obtained with a smaller particle size using a titanium dioxide nanotube (TNT) electrode plate. However, the particle size of TNT-CoHA is smaller than that of Ti-CoHA. The crystal size of the internal cobalt oxide of CoHA was calculated by using an XRD pattern. The results indicate that the crystal size of cobalt oxide in TNT-CoHA is larger than that of the cobalt oxide in Ti-CoHA. The larger crystal size of the cobalt oxide in TNT-CoHA makes the saturation magnetization (Ms) of TNT-CoHA 12.6 times higher than that of Ti-CoHA. The contrast in MRIs is related to the magnetic properties of the particles. Therefore, TNT-CoHA has good image contrast at low concentrations in T₂ images. The relaxivity coefficient of the CoHA was higher for TNT-CoHA (340.3 mM⁻¹s⁻¹) than Ti-CoHA (211.7 mM⁻¹s⁻¹), and both were higher than the commercial iron nanoparticles (103.0 mM⁻¹s⁻¹). We showed that the TNT substrate caused an increase in the size of the cobalt oxide crystal of TNT-CoHA, thus effectively improving the magnetic field strength and MRI image recognition. It was also shown that the relaxivity coefficient rose with the Ms. Evaluation of biocompatibility of CoHA using human osteosarcoma cells (MG63) indicated no toxic effects. On the other hand, CoHA had an excellent antibacterial effect, as shown by E. coli evaluation, and the effect of TNT-CoHA powder was higher than that of Ti-CoHA powder. In summary, TNT-CoHA deposited electrochemically on the TNT substrates can be considered as a potential candidate for the application as an MRI contrast agent. This paper is a comparative study of how different electrode plates affect the magnetic and MRI image contrast of cobalt-substituted hydroxyapatite (CoHA) nanomaterials.