Amino acid endcapped poly(p-dioxanone): synthesis and crystallization

Preparation of healing promotive alanyl-glutamine-poly(p-dioxanone) electrospun membrane integrated with gentamycin and its application for intestinal anastomosis in rats

Anastomosis surgery at the intestinal site is performed on millions of individuals every year. However, several persistent complications, such as anastomotic leakage, abnormal adhesion, and anastomotic stenosis, have been observed after the surgery. For promoting anastomotic healing and to overcome the challenges mentioned above, re-epithelialization at anastomotic sites is crucial. In this study, an epithelialization-promoting macromolecular prodrug Ala-Gln-PPDO was prepared and processed into fibrous membranes by electrospinning. Ala-Gln and gentamicin were sustainably released from the electrospun membranes with degradation of these membranes to promote the proliferation of rat intestinal epithelial cells and suppress the proliferation of Staphylococcus aureus and Escherichia coli. The comprehensive repair effects of Ala-Gln-PPDO membranes have been evaluated in rat models of intestinal anastomosis in this study. Application of Ala-Gln-PPDO membranes, especially the gentamicin-incorporated Ala-Gln-PPDO ones, could prevent adhesion between the injured intestine and surrounding intestinal tissues. In addition, they did not affect the healing strength of anastomotic stoma negatively and could promote re-epithelialization at the anastomotic sites. Furthermore, the gentamicin-incorporated Ala-Gln-PPDO membranes could relieve stenosis at anastomotic sites. The gentamicin-incorporated Ala-Gln-PPDO electrospun membrane is a promising, comprehensive implantable material for promoting healing after gastrointestinal anastomosis owing to its effects involving the promotion of re-epithelialization, prevention of adhesion, and relieving of anastomotic stenosis.

Enzymatic Synthesis of Amino Acids Endcapped Polycaprolactone: A Green Route Towards Functional Polyesters

ε-caprolactone (CL) has been enzymatically polymerized using α-amino acids based on sulfur (methionine and cysteine) as (co-)initiators and immobilized lipase B of Candida antarctica (CALB) as biocatalyst. In-depth characterizations allowed determining the corresponding involved mechanisms and the polymers thermal properties. Two synthetic strategies were tested, a first one with direct polymerization of CL with the native amino acids and a second one involving the use of an amino acid with protected functional groups. The first route showed that mainly polycaprolactone (PCL) homopolymer could be obtained and highlighted the lack of reactivity of the unmodified amino acids due to poor solubility and affinity with the lipase active site. The second strategy based on protected cysteine showed higher monomer conversion, with the amino acids acting as (co-)initiators, but their insertion along the PCL chains remained limited to chain endcapping. These results thus showed the possibility to synthesize enzymatically polycaprolactone-based chains bearing amino acids units. Such cysteine endcapped PCL materials could then find application in the biomedical field. Indeed, subsequent functionalization of these polyesters with drugs or bioactive molecules can be obtained, by derivatization of the amino acids, after removal of the protecting group.