New generation of poly(ortho esters): synthesis, characterization, kinetics, sterilization and biocompatibility

Zignani, M.; Merkli, Alain; Sintzel, Martina Barbara; Bernatchez, Stéphanie F.; Kloeti, Werner; Heller, Jorge; Tabatabay, C.; Gurny, Robert

doi:10.1016/s0168-3659(97)00050-3

Cited by 34 publications

(20 citation statements)

References 59 publications

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“…This is in accordance with what is described for other biodegradable polymers. 43,[45][46][47][48][49][50] The release profile is similar for DEX and MP, with 27 and 28% of release for the first 24 h, respectively. This initial burst is then followed by a slower release until 750 h (30 days), in which 45% of entrapped DEX and 40% of MP are released.…”

Section: Entrapment Efficiencymentioning

confidence: 86%

Entrapment ability and release profile of corticosteroids from starch‐based microparticles

Silva

Costa

Neves

et al. 2005

J Biomedical Materials Res

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Abstract:We previously described the synthesis of starchbased microparticles that were shown to be bioactive (when combined with Bioactive Glass 45S5) and noncytotoxic. To further assess their potential for biomedical applications such as controlled release, three corticosteroids with a similar basic structure-dexamethasone (DEX), 16␣-methylprednisonole (MP), and 16␣-methylprednisolone acetate (MPA)-were used as models for the entrapment and release of bioactive agents. DEX, MP, and MPA were entrapped into starch-based microparticles at 10% wt/wt of the starch-based polymer and the loading efficiencies, as well as the release profiles, were evaluated. Differences were found for the loading efficiencies of the three corticosteroids, with DEX and MPA being the most successfully loaded (82 and 84%, respectively), followed by MP (51%). These differences might be explained based on the differential distribution of the molecules within the matrix of the microparticles. Furthermore, a differential burst release was observed in the first 24 h for all corticosteroids with DEX and MP being more pronounced (around 25%), whereas only 12% of MPA was released during the same time period. Whereas the water uptake profile can account for this first stage burst release, the subsequent slower release stage was mainly attributed to degradation of the microparticle network. Differences in the release profiles can be explained based on the structure of the molecule, because MPA, a more bulky and hydrophobic molecule, is released at a slower rate compared with DEX and MP. In this work, it is shown that these carriers were able to sustain a controlled release of the entrapped corticosteroids over 30 days, which confirms the potential of these systems to be used as carriers for the delivery of bioactive agents.

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Section: Entrapment Efficiencymentioning

confidence: 86%

Entrapment ability and release profile of corticosteroids from starch‐based microparticles

Silva

Costa

Neves

et al. 2005

J Biomedical Materials Res

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“…Monodisperse polystyrene standards were used for calibration. 2 All chemicals used were reagent grade.…”

Section: Polymer Synthesismentioning

confidence: 99%

“…The added substances, magnesium hydroxide [Mg(OH) 2 ] or dexamethasone sodium phosphate (DEX) (Sigma Chemie AG, Buchs, Switzerland), were previously ␥-sterilized at 2.0 MRad and mixed with the aseptically prepared polymer under sterile conditions at room temperature. 2 The final concentration of incorporated substance was 1% w/w. The mixture was then poured into a 1.0-mL hypodermic syringe, each injection amounting to 50 or 100 L. Different formulations were tested: POE LMW , POE HMW , POE HMW with Mg(OH) 2 , and POE HMW with DEX.…”

Section: Sample Preparationmentioning

confidence: 99%

“…1,2 Glaucoma filtration surgery is realized by creating a fistula between the anterior chamber of the eye and the subconjunctival space, allowing the drainage of aqueous humor to reduce the intraocular pressure and preserve vision in patients suffering from severe glaucoma. 3 Inhibition of subconjunctival fibrosis is desired, and the surgical procedure fails when the scarred conjunctiva adheres to the episcleral tissue and the bulbar sclera.…”

Section: Introductionmentioning

confidence: 99%

“…18 Poly(ortho ester) biocompatibility has been extensively investigated after subcutaneous 20 as well as subconjunctival administration. 21,22 Significant improvement of biotolerance has been obtained by using aseptically synthesized polymers instead of ␥-sterilized batches 2 and by controlling the microenvironmental pH around the device during polymer degradation. 23 So far, the overall intraocular biocompatibility has yet to be assessed.…”

Section: Introductionmentioning

confidence: 99%

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A viscous bioerodible poly(ortho ester) as a new biomaterial for intraocular application

Einmahl

Behar‐Cohen

Tabatabay

et al. 2000

J. Biomed. Mater. Res.

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The biocompatibility of a viscous, hydrophobic, bioerodible poly(ortho ester) (POE) intended for intraocular application was investigated. POE was evaluated as a blank carrier and as containing modulators of degradation. Each formulation was injected intracamerally and intravitreally in rabbit eyes, and clinical and histological examinations were performed postoperatively for 2 weeks. In the case of intracameral injections, polymer biocompatibility appeared to depend on the amount injected in the anterior chamber. When 50 microL was administered, the polymer degraded within 2 weeks, and clinical observations showed good biocompatibility of POE with no toxicity to the ocular tissues or increase in intraocular pressure. The injection of a larger volume, 100 microL, of POE, appeared inappropriate because of direct contact of polymeric material with the corneal endothelium, and triggered reversible edema and inflammation in the anterior chamber of the eye that regressed after a few days. After intravitreal administration, POE was well tolerated and no inflammatory reaction developed during the observation period. The polymer degraded slowly, appearing as a round whitish bubble in the vitreous cavity. The presence of modulators of degradation both improved POE biocompatibility and prolonged polymer lifetime in the eye. POE appears to be a promising biomaterial for clinical intraocular application.

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Synthesis of Poly(acyclic orthoester)s: Acid‐Sensitive Biomaterials for Enhancing Immune Responses of Protein Vaccine

Xing

Liu

et al. 2020

Angewandte Chemie

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While poly(acyclic orthoester)s (PAOEs) have many appealing features for drug delivery, their application is significantly hindered by a lack of facile synthetic methods. Reported here is a simple method for synthesizing acyclic diketene acetal monomers from diols and vinyl ether, and their polymerization with a diol to first synthesize PAOEs. The PAOEs rapidly hydrolyze at lysosomal pH. With the help of a cationic lipid, ovalbumin, a model vaccine antigen was efficiently loaded into PAOEs nanoparticles using a double emulsion method. These nanoparticles efficiently delivered ovalbumin into the cytosol of dendritic cells and demonstrated enhanced antigen presentation over poly(lactic‐co‐glycolic acid) (PLGA) nanoparticles. PAOEs are promising vehicles for intracellular delivery of biopharmaceuticals and could increase the utility of poly(orthoesters) in biomedical research.

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New generation of poly(ortho esters): synthesis, characterization, kinetics, sterilization and biocompatibility

Cited by 34 publications

References 59 publications

Entrapment ability and release profile of corticosteroids from starch‐based microparticles

Entrapment ability and release profile of corticosteroids from starch‐based microparticles

A viscous bioerodible poly(ortho ester) as a new biomaterial for intraocular application

Synthesis of Poly(acyclic orthoester)s: Acid‐Sensitive Biomaterials for Enhancing Immune Responses of Protein Vaccine

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