The effect of mechanical loads on the degradation of aliphatic biodegradable polyesters

Abstract

Aliphatic biodegradable polyesters have been the most widely used synthetic polymers for developing biodegradable devices as alternatives for the currently used permanent medical devices. The performances during biodegradation process play crucial roles for final realization of their functions. Because physiological and biochemical environment in vivo significantly affects biodegradation process, large numbers of studies on effects of mechanical loads on the degradation of aliphatic biodegradable polyesters have been launched during last decades. In this review article, we discussed the mechanism of biodegradation and several different mechanical loads that have been reported to affect the biodegradation process. Other physiological and biochemical factors related to mechanical loads were also discussed. The mechanical load could change the conformational strain energy and morphology to weaken the stability of the polymer. Besides, the load and pattern could accelerate the loss of intrinsic mechanical properties of polymers. This indicated that investigations into effects of mechanical loads on the degradation should be indispensable. More combination condition of mechanical loads and multiple factors should be considered in order to keep the degradation rate controllable and evaluate the degradation process in vivo accurately. Only then can the degradable devise achieve the desired effects and further expand the special applications of aliphatic biodegradable polyesters.

Manufacturing and Characterization of Functionalized Aliphatic Polyester from Poly(lactic acid) with Halloysite Nanotubes

“…These environmentally friendly polymers could be classified into three different groups with different environmental connotations [8]. One group is composed of biodegradable petroleum-derived polymers such as most aliphatic polyesters, i.e., poly(ε-caprolactone)—PCL, poly(butylene succinate)—PBS, poly(glycolic acid)—PGA and so on [9,10,11]. Although they are petroleum-derived polymers, they show interest from an environmental standpoint as they can be disintegrated in controlled compost soil conditions.…”

In Vitro Degradation of Electrospun Poly(Lactic-Co-Glycolic Acid) (PLGA) for Oral Mucosa Regeneration

“…As shown in Table 1 , the control non-irradiated PLGA presented higher molecular weights ( M n = 253,900 and M w = 460,400) while the irradiated membranes ( Table 2 ) showed a significant decrease in the molecular weights ( M n = 75,000 and M w =156,300), revealing that sterilization by gamma irradiation caused a strong PLGA degradation (66% of M w lost). High molecular weight polymers, as the non-irradiated PLGA used in the present study, have long chains, being more susceptible to the drastic decrease of average molecular weight when exposed to hydrolytic fluids [ 28 ]. In this regard, a drastic decrease in the molecular weight of the non-irradiated nonwoven immersed in saliva at 30 days was observed ( Table 1 ) when compared to the irradiated nonwoven immersed in saliva at the same time point, both relative to each control (first lines Table 1 and Table 2 ).…”

“…The slight increase in M n and M w observed for two samples after immersion at 15 days in SBS and DMEM is under the expected uncertainty for the GPC technique and, since there is no reason for such an increase, it was considered an experimental error. Considering mass loss during degradation in solutions, Perron et al showed that the percentage of water absorption after immersion of PLGA (85:15) in phosphate buffer saline (PBS) and distilled water (dH 2 O) after 84 day, were solution dependent: (i) after immersion in PBS solution, scaffolds water absorption increased from 0 to 100% after 7 days and remained constant for the other periods of degradation and (ii) the water uptake of the scaffold exposed to dH 2 O varied from 0 to 150% after 7 days of degradation and increased up to 200% towards the end of the degradation study [ 28 ]. Authors observed that mass loss was within 4% throughout the full degradation period, and as mass loss water uptake decreases [ 29 ].…”

“…As demonstrated by a decrease in T g observed by DSC analyses of non-irradiated and irradiated nonwovens in comparison with the respective controls, a plasticization (water absorption by the polymer chains) probably occurred in the bulk material depending on the immersion time. Li et al [ 28 ] reported that a decrease in T g was related to an initial process of degradation caused by mass loss. Effectively, our GPC analyses showed a tendency of decreasing M w in non-irradiated and irradiated nonwovens immersed in the different solutions in comparison with controls.…”

Biomechanical Behaviour and Biocompatibility of Ureidopyrimidinone-Polycarbonate Electrospun and Polypropylene Meshes in a Hernia Repair in Rabbits

“…Degradation of the implants was faster in gap-bridged defects than in reinforced areas. A higher load may have changed the conformational strain energy and morphology of the implant, affecting the stability of the polymer [34]. In addition, it may lead to cracking of the microfibres, hence an increase in the surface area for the oxidative degradation induced by the host inflammatory response.…”