A Simple Route to Aqueous Suspensions of Degradable Copolymer Nanoparticles from Radical Ring-Opening Polymerization-Induced Self-Assembly (rROPISA)

Degradable polymer nanoparticles are almost exclusively obtained by formulation of preformed degradable polymers, such as aliphatic polyesters, thus resulting is very low nanoparticle concentrations and limited structural diversity. On the other hand, many different vinyl polymers can be obtained by polymerization in aqueous dispersed media, but their non-degradability limits their use especially in the biomedical field. Herein, we combined the best of both worlds by developing a two-step radical ring-opening copolymerization-induced self-assembly (rROPISA) process, allowing to generate aqueous suspensions of narrowly dispersed, degradable vinyl copolymer nanoparticles at 15 wt.% solid contents, containing cyclic ketene acetal (CKA) units in the nanoparticle core. This strategy relied on rROPISA in DMF, followed by a simple transfer step to water. It was successfully applied to the three main CKAs used in rROP and yielded nanoparticles of ~80–215 nm in diameter with tunable amount of CKA up to 21 mol.%. Successful incorporation of ester groups in the copolymers was demonstrated by hydrolytic degradation of both the copolymers and the nanoparticles. The nanoparticles’ cytocompatibility was then established by cell viability assays and cell morphology observation with three representative healthy cell lines. Not only this synthetic strategy could be of great potential for drug delivery applications, but it can also be beneficial to other research fields to yield more environmentally friendly materials involving the use of latexes, such as paints or coatings.

A bone replacement-type calcium phosphate cement that becomes more porous in vivo by incorporating a degradable polymer

This study investigated whether mixing low viscosity alginic acid with calcium phosphate cement (CPC) causes interconnected porosity in the CPC and enhances bone replacement by improving the biological interactions. Furthermore, we hypothesized that low viscosity alginic acid would shorten the setting time of CPC and improve its strength. CPC samples were prepared with 0, 5, 10, and 20% low viscosity alginic acid. After immersion in acetate buffer, possible porosification in CPC was monitored in vitro using scanning electron microscopy (SEM), and the setting times and compressive strengths were measured. In vivo study was conducted by placing CPC in a hole created on the femur of New Zealand white rabbit. Microcomputed tomography and histological examination were performed 6 weeks after implantation. SEM images confirmed that alginic acid enhanced the porosity of CPC compared to the control, and the setting time and compressive strength also improved. When incorporating a maximum amount of alginic acid, the new bone mass was significantly higher than the control group (P = 0.0153). These biological responses are promising for the translation of these biomaterials and their commercialization for clinic applications.

Biodegradation Study of Potato Starch-based Bioplastic

Background: Plastics are indispensable for our society. The extensive use of petroleum-based plastic and dumping of the same in soil and water body greatly affects our environment and biodiversity. However, biodegradable plastics can reduce the volume of waste in packaging materials. Therefore, biomass-derived polymers are promising alternatives of the petroleum-based non-degradable polymer to address the environmental issues. Objective: A large number of reports on the synthesis and characterization of starch-based bioplastic are available in the literature. However, a detailed biodegradation study of the starch-based bioplastic is rarely reported. We have prepared potato starch-based bioplastic with the combination of various plasticizers (glycerol, sorbitol, and xylitol) through hydrogel formation and carried out their biodegradation study. Method: Present study investigated the biodegradation of potato starch-based bioplastic in the natural environment, in cultured bacteria, and with fungal α-amylase. Results: Starch-based plastic is completely degraded in the natural environment within two months. Bacteria culture in solid media resulted in various types of bacterial colonies. Among the various bacterial colonies, the white circular colony was the major bacteria that degrade starch-based plastic. Furthermore, we screened the starch-based plastic degrading bacteria and isolated the pure culture through the streak plate method. Conclusion: n presence of cultured bacteria and with fungal α-amylase, starch-based plastic is completely degraded within 96h and 48h respectively.