Biodegradable polymers are appealing material for the manufacturing of surgical implants as such implants break down in vivo, negating the need for a subsequent operation for removal. Many biocompatible polymers produce acidic breakdown products that can lead to localized inflammation and osteolysis. This study assesses the feasibility of fabricating implants out of poly(propylene carbonate) (PPC)-starch that degrades into CO and water. The basic compression modulus of PPC-starch (1:1 w/w) is 34 MPa; however, the addition of glycerol (1% w/w) and water as plasticizers doubles this value and enhances the surface wettability. The bioactivity and stiffness of PPC-starch blends is increased by the addition of bioglass microparticles (10% w/w) as shown by in vitro osteoblast differentiation assay and mechanical testing. MicroCT analysis confirms that the bioglass microparticles are evenly distributed throughout biomaterial. PPC-starch-bioglass was tested in vivo in two animal models. A murine subcutaneous pellet degradation assay demonstrates that the PPC-starch-bioglass blend's volume fraction loss is 46% after 6 months postsurgery, while it is 27% for poly(lactic acid). In a rat knee implantation model, PPC-starch-bioglass screws inserted into the distal femur show osseointegration with no localized adverse effects after 3 and 12 weeks. These data support the further development of PPC-starch-bioglass as a medical biomaterial.
Injectable
and phase-transitioning carriers from natural polysaccharides
have great potential for the minimally invasive delivery of therapeutic
proteins in the field of bone tissue engineering. In this study, a
novel and highly viscous drug carrier was synthesized by a sequential
process of deoxyribose polycondensation and esterification. The effect
of synthesis parameters on the molecular weight, viscosity, and adhesion
of the material was studied and correlated to temperature and time
of polycondensation (T
p and t
p), time and temperature of esterification (T
e and t
e), and the molar ratio
of the monomer (R). The formulations were evaluated
for molecular weight and distribution properties using GPC, chemical
structures by FTIR and NMR spectra, and rheological properties using
a rheometer. Formulations illustrated a wide range of viscosities
(0.736 to 2225 Pa s), adhesion (0.896 to 58.45 N), and molecular weights
(637 to 4216 Da), where viscosity was significantly reduced in the
presence of low amounts of solvents (10–20%). The sustained
release of BSA was observed over 42 days in vitro. The biocompatibility
of poly(deoxyribose) isobutyrate (PDIB) as well as its potential as
a bone morphogenetic protein delivery system was assessed in vivo
using a rat ectopic bone model, where bone nodules were observed at
2 weeks. In summary, PDIB is a promising molecule with multiple applications
for protein delivery, including for bone tissue engineering.
Lithium-ion (Li-ion) battery cells are influenced by high energy, reliability, and robustness. However, they produce a noticeable amount of heat during the charging and discharging process. This paper presents an optimal thermal management system (TMS) using a phase change material (PCM) and PCM-graphite for a cylindrical Li-ion battery module. The experimental results show that the maximum temperature of the module under natural convection, PCM, and PCM-graphite cooling methods reached 64.38, 40.4, and 39 °C, respectively. It was found that the temperature of the module using PCM and PCM-graphite reduced by 38% and 40%, respectively. The temperature uniformity increased by 60% and 96% using the PCM and PCM-graphite. Moreover, some numerical simulations were solved using COMSOL Multiphysics® for the battery module.
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