Anandamide-loaded nanoparticles: Preparation and characterization

Objective: Preparation and characterization of anandamide (N-arachidonoyl-ethanolamine, AEA) loaded polycaprolactone nanoparticles (PCL NP) as a research tool to clarify the presence of an AEA transporter in cell membranes and to avoid AEA plastic adsorption and instability.

Materials and methods: High performance liquid chromatography and light scattering were used to determine encapsulation efficiency, particle size, drug release, permeability and stability.

Results: A high encapsulation efficiency 96.05?±?1.77% and a particle size of 83.52?±?21.38?nm were obtained. Nearly 40% of AEA remained in the NP after a 99.9% dilution and only 50% was released after 24?h at 37°C with a 99% dilution. PCL NP prevented the adsorption of the drug to polypropylene or polystyrene, but not to acrylic multiwell plates. Drug permeability through artificial membranes was low (10^?7 to 10^?8?cm/s) and was affected by the presence of NP. NP increased AEA stability in suspension (drug half-life 431?h vs. 12?h) and freeze-dried with 5% sucrose.

Conclusion: This article presents the first study where stable AEA-loaded NP with high encapsulation efficiencies have been obtained.     

Preparation of Biodegradable Polycaprolactone/Poly (ethylene glycol)/Polycaprolactone (PCEC) Nanoparticles

Biodegradable polyetherester copolymer (PCL/PEG/PCL, PCEC) was synthesized by ring-opening polymerization of ε-caprolactone initiated by poly(ethylene glycol) (PEG). The PCEC nanoparticles were prepared by solvent diffusion method or w/o/w double emulsion method. The obtained particles' morphology was observed on scanning electron microscopy, and the particle size distribution was determined using Malvern laser particle sizer. Bovine serum albumin was used as the model water-soluble protein drug, which was successfully encapsulated in PCEC nanoparticles, the drug release behavior was studied in detail. The hydrolytic degradation behavior of the PCEC nanoparticles was also studied.     

A bioactive “self-fitting” shape memory polymer scaffold with potential to treat cranio-maxillo facial bone defects

While tissue engineering is a promising alternative for treating critical-sized cranio-maxillofacial bone defects, improvements in scaffold design are needed. In particular, scaffolds that can precisely match the irregular boundaries of bone defects as well as exhibit an interconnected pore morphology and bioactivity would enhance tissue regeneration. In this study, a shape memory polymer (SMP) scaffold was developed exhibiting an open porous structure and the capacity to conformally “self-fit” into irregular defects. The SMP scaffold was prepared via photocrosslinking of poly(ε-caprolactone) (PCL) diacrylate using a SCPL method, which included a fused salt template. A bioactive polydopamine coating was applied to coat the pore walls. Following exposure to warm saline at T > T_trans (T_trans = T_m of PCL), the scaffold became malleable and could be pressed into an irregular model defect. Cooling caused the scaffold to lock in its temporary shape within the defect. The polydopamine coating did not alter the physical properties of the scaffold. However, polydopamine-coated scaffolds exhibited superior bioactivity (i.e. formation of hydroxyapatite in vitro), osteoblast adhesion, proliferation, osteogenic gene expression and extracellular matrix deposition.     

Effect of umbilical cord serum coated 3D PCL/alginate scaffold for mastoid obliteration

Objective

Human umbilical cord serum (hUCS) has a lot of growth factors. To date, there are no reports on stimulating effect of hUCS in osteogenesis. The purpose of this study is to evaluate enhancing effect of hUCS in osteogenesis by mastoid obliteration combined with bony scaffold.

Materials and methods

The fabrication procedure for obtaining PCL/alginate/hUCS was performed. The bulla obliteration was done using PCL/alginate/hUCS in the experimental group and PCL in the control group. To assess the early active mineralization of new bone formation, guinea pigs of each group received an intraperitoneal infusion with alizarin red at 6 weeks post-surgery. The animals of each group were sacrificed 8 weeks post-surgery. Ex vivo microCT and histologic observation were performed.

Results

MicroCT finding shows more radiopaque change within the pores in the experimental group compared to the control group. Stereomicroscopic and SEM findings show new bone formation of the pores in the experimental group. However, the pores between strands almost all remained in the control group. Corresponding histological observations for the stimulatory effects of hUCS showed osteogenesis in the pores between the strands compared to the control group.

Conclusion

Our data suggest that hUCS coated 3D porous PCL scaffold in mastoid obliteration provides enhanced osteogenesis. Therefore, we suggest that our hUCS coated 3D porous PCL could be used in mastoid obliteration in the future.     

Controllable mineral coatings on PCL scaffolds as carriers for growth factor release

In this study, we have developed mineral coatings on polycaprolactone scaffolds to serve as templates for growth factor binding and release. Mineral coatings were formed using a biomimetic approach that consisted in the incubation of scaffolds in modified simulated body fluids (mSBF). To modulate the properties of the mineral coating, which we hypothesized would dictate growth factor release, we used carbonate (HCO₃) concentration in mSBF of 4.2 mm, 25 mm, and 100 mm. Analysis of the mineral coatings formed using scanning electron microscopy indicated growth of a continuous layer of mineral with different morphologies. X-ray diffraction analysis showed peaks associated with hydroxyapatite, the major inorganic constituent of human bone tissue in coatings formed in all HCO₃ concentrations. Mineral coatings with increased HCO₃ substitution showed more rapid dissolution kinetics in an environment deficient in calcium and phosphate but showed re-precipitation in an environment with the aforementioned ions. The mineral coating provided an effective mechanism for growth factor binding and release. Peptide versions of vascular endothelial growth factor (VEGF) and bone morphogenetic protein 2 (BMP2) were bound with efficiencies up to 90% to mineral mineral-coated PCL scaffolds. We also demonstrated sustained release of all growth factors with release kinetics that were strongly dependent in the solubility of the mineral coating.     

Development of bacterial cellulose and polycaprolactone (PCL) based composite for medical material

Polycaprolactone (PCL)/bacterial cellulose (BC) composite was successfully prepared via film casting. BC was extracted from nata de coco using alkaline purification. 1%,5%,10%,20%,30% and 50% v/v of BC was incorporated into PCL composite. The structural, morphological, thermal, swelling, and degradation properties were investigated. It was found that the intensity of O–H stretching was observed with respect to amount of BC content. However, with high BC content, the percent of crystallinity was decreased. Porosity was observed as a microstructure of BC/PCL composite. It was remarkable to note that thermal decomposition behavior was stable up to 400 °C. The crystallization temperature was increased, whereas the melting temperature was decreased, when high amount of BC was integrated. No significant change of swelling behavior was observed for DI water and PBS solution when BC was added. The swelling behavior and degradation properties were observed for 6 h and 4 weeks, respectively. Therefore, bacterial cellulose and polycaprolactone based composite can significantly be provide the benefit as an excellent candidate for wound dressing application.