The degradation of poly(ϵ-caprolactone) in rabbits, rats, and water was studied by measurement of changes in intrinsic viscosity, molecular weight, crystallinity, Young's modulus, and weight. Degradation proceeds by nonenzymatic random hydrolytic cleavage of ester linkages. The process is autocatalytic, and the kinetic relationship Mn/Mno = exp(–kt) is observed until the Mn has decreased to approximately 5000. Significant weight loss is not observed until this point but, once initiated, the rate of weight loss depends markedly on the particle size. Chain scission is associated with an increase in crystallinity, which partly determines the rate of degradation.

Aliphatic polyesters. I. The degradation of poly(ϵ‐caprolactone) in vivo

The synthesis of aliphatic polyesters by polycondensation and ring-opening polymerization is reviewed. This includes homopolyesters, random, block, graft, star, and hyper-branched (co)polyesters. Recent progress in the synthesis of high molecular weight aliphatic polyesters is described. Specific properties of these polymers are also given. The biomedical and ecological applications of these biodegradable polymers show their technological importance and relevance.

Aliphatic Polyesters: Synthesis, Properties and Applications

Polymers for biodegradable medical devices. 1. The potential of polyesters as controlled macromolecular release systems

INCREASING public concern about the treatment of waste materials has stimulated the study of the biodegradation of synthetic polymers. Among synthetic polymers, aliphatic polyesters are generally known to be susceptible to biological attack1–5, but there are few reports of enzymes involved in their degradation. Bell et al.6 recently showed that the molecular weight of polycaprolactone (PCL) decreases on exposure to the acid protease from Rhizopus chinensis for 6–10 d (decreasing from 13,000 to 10,000). In addition, Tabushi et al.7 have found that polyesters composed of phenyllactic acid and lactic acid are hydrolysed by α-chymotrypsin. We showed previously that a polyester-degrading enzyme from Penicillium sp. strain 14-3, purified to a homogeneous state as exhibited by ultracentrifugal analysis and polyacrylamide gel electrophoresis, has properties resembling lipase8. It was not previously recognised that lipase acts on polyesters. We report here that several commercial lipases and an esterase also hydrolyse polyesters, and that Rh. delemar lipase is capable of hydrolysing various kinds of polyesters.

Hydrolysis of polyesters by lipases

Crystallization and melting behavior of three biodegradable poly(alkylene succinates). A comparative study

Polycaprolactone is degraded by the mold P. pullulans in the presence of other nutrients. The weight loss from solid polymer films covered by a nutrient agar gel on which colonies are growing is used to establish comparative rates of degradation. There is substantial loss (16 mg/cm2 surface area) from a whole polymer of low (2,000) molecular weight in three weeks at 30°C. A high (30,000) molecular weight whole polymer degrades about 0.15 as much in the same time period. A fraction in the same range (38,000) but with a narrower molecular weight distribution shows no significant loss. This indicates that whole polymers of high molecular weight may lose only a portion of their distribution by microbial degradation in short-term tests. This hypothesis is tested by making mixtures of high (61,000) molecular weight with low (2,000) molecular weight polymer. Degradation is directly proportional to the low molecular weight content in these short-term tests with a single species of mold. Other workers have shown previously that in long-term, soil-burial tests, even a high (40,000) molecular weight polycaprolactone is essentially completely degraded after one year.

Microbial degradation of polyesters: Polycaprolactone degraded by P. pullulans†

Abstract Biomaterials with antimicrobial activity are gaining attention due to their biodegradability and efficacy in interacting with a wide range of microorganisms. A new cellulose nano-biomaterial, endospermic nanocellulose crystals (ENC) obtained from parenchymal tissue of ivory nut endosperm, has a natural capacity as a universal binder. This feature is enhanced when it is chemically functionalized, and can be exploited in the fight against microbes. We tested the ability of sulfated ENC in aqueous suspension to encapsulate viruses through a crosslinking reaction mediated by cations. 0.25% w/v ENC suspensions efficiently encapsulated spike (S) protein, preventing its interaction with ACE2 receptor. ENC was further able to encapsulate SARS-CoV-2 pseudoviruses and prevent infection of 293T-ACE2 cells. ENC also suppressed infection of MT-4 cells with HIV-1 LAI.04 . This antiviral activity of sulfated ENC is due to the irreversible interaction of ENC with viral particles mediated by crosslinking, as antiviral activity was less effective in the absence of cations. Additionally, ENC was used as a matrix to immobilize recombinant ACE2 receptors and anti-S IgG, creating molecular lures that efficiently inhibited SARS-CoV-2 infections in vitro . These results show that sulfated ENC from ivory nuts can be used as an efficient antiviral material.

/pdf/sulfated-endospermic-nanocellulose-crystals-prevent-the-15npqhqx.pdf

Sulfated endospermic nanocellulose crystals prevent the transmission of SARS-CoV-2 and HIV-1

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Microbial degradation of polyesters: Polycaprolactone degraded by P. pullulans†

Sulfated endospermic nanocellulose crystals prevent the transmission of SARS-CoV-2 and HIV-1