MgH2/PEG initiating system for ring opening polymerization of lactone and lactide

Guerrouani, Nadia; Mas, André; Schué, François

doi:10.1515/epoly.2010.10.1.224

Cited by 2 publications

(3 citation statements)

References 27 publications

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“…At the lyophilization settings employed in this study, both glucose and PEG are found to be unsuitable as cryoprotectants for the freeze-drying of PBCA-MB. This is expected to be due to the low collapse temperature and the low glass transition temperature of glucose and PEG (i.e., −41 °C and −62.3 °C, respectively), resulting in disintegration and/or coalescence of PBCA-MB during freeze-drying [28,29]. For efficient lyophilization, freeze-drying should be carried out at temperatures below the collapse temperature of the product [28].…”

Section: Resultsmentioning

confidence: 99%

Shelf-Life Evaluation and Lyophilization of PBCA-Based Polymeric Microbubbles

et al. 2019

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Poly(n-butyl cyanoacrylate) microbubbles (PBCA-MB) are extensively employed for functional and molecular ultrasound (US) imaging, as well as for US-mediated drug delivery. To facilitate the use of PBCA-MB as a commercial platform for biomedical applications, it is important to systematically study and improve their stability and shelf-life. In this context, lyophilization (freeze drying) is widely used to increase shelf-life and promote product development. Here, we set out to analyze the stability of standard and rhodamine-B loaded PBCA-MB at three different temperatures (4 °C, 25 °C, and 37 °C), for a period of time of up to 20 weeks. In addition, using sucrose, glucose, polyvinylpyrrolidone (PVP), and polyethylene glycol (PEG) as cryoprotectants, we investigated if PBCA-MB can be lyophilized without affecting their size, concentration, US signal generation properties, and dye retention. Stability assessment showed that PBCA-MB remain largely intact for three and four weeks at 4 °C and 25 °C, respectively, while they disintegrate within one to two weeks at 37 °C, thereby compromising their acoustic properties. Lyophilization analyses demonstrated that PBCA-MB can be efficiently freeze-dried with 5% sucrose and 5% PVP, without changing their size, concentration, and US signal generation properties. Experiments involving rhodamine-B loaded MB indicated that significant dye leakage from the polymeric shell takes place within two to four weeks in case of non-lyophilized PBCA-MB. Lyophilization of rhodamine-loaded PBCA-MB with sucrose and PVP showed that the presence of the dye does not affect the efficiency of freeze-drying, and that the dye is efficiently retained upon MB lyophilization. These findings contribute to the development of PBCA-MB as pharmaceutical products for preclinical and clinical applications.

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Section: Resultsmentioning

confidence: 99%

Shelf-Life Evaluation and Lyophilization of PBCA-Based Polymeric Microbubbles

et al. 2019

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“…For the synthesis of PCL, racemization is not an issue, which gives greater scope for exploiting calcium hydride to its full potential as an initiator. Analogous studies using magnesium hydride showed efficient polymerization of both PLA and PCL copolymers of PEG and poly(vinyl alcohol) at 120 °C. However, the polymerization conditions were limited in scope which restricted the analysis of the polymerization mechanism.…”

Section: Introductionmentioning

confidence: 99%

“…For the synthesis of PCL, racemization is not an issue, which gives greater scope for exploiting calcium hydride to its full potential as an initiator. Analogous studies 13,14 using magnesium hydride showed efficient polymerization of both PLA and PCL copolymers of PEG and poly(vinyl alcohol) at 120 ∘ C. However, the polymerization conditions were limited in scope which restricted the analysis of the polymerization mechanism. In the study reported herein, the effect of varying synthetic parameters such as temperature and reactant concentration has been investigated in detail in order to better understand the mechanism of polymerization.…”

Section: Introductionmentioning

confidence: 99%