Multifunctional Biocompatible and Biodegradable Folic
Acid Conjugated Poly(ε-caprolactone)–Polypeptide Copolymer
Vesicles with Excellent Antibacterial Activities
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Abstract
Cancer patients after chemotherapy
may also suffer bacterial attack
due to badly decreased immunity. Although with high bacterial efficacy,
conventional antibiotics are prone to inducement of drug resistance
and may be not suitable for some cancer patients. In contrast, antibacterial
peptides are highly effective in inhibiting bacteria without inducing
resistance in pathogens. Presented in this article is a novel kind
of highly effective antibacterial peptide-based biocompatible and
biodegradable block copolymer vesicle. The copolymer is poly(ε-caprolactone)-<i>block</i>-poly[phenylalanine-<i>stat</i>-lysine-<i>stat</i>-(lysine-folic acid)] [PCL<sub>19</sub>-<i>b</i>-poly[Phe<sub>12</sub>-<i>sta</i>t-Lys<sub>9</sub>-<i>stat</i>-(Lys-FA)<sub>6</sub>]], which can self-assemble into
vesicles in aqueous solution. The biocompatible and biodegradable
PCL forms the vesicle membrane, whereas the poly[Phe<sub>12</sub>-<i>sta</i>t-Lys<sub>9</sub>-<i>stat</i>-(Lys-FA)<sub>6</sub>] block constitutes the vesicle coronas. Compared to the individual
polymer chains, the vesicles showed enhanced antibacterial activities
against both Gram-positive and Gram-negative bacteria (16 μg
mL<sup>–1</sup>) due to the locally concentrated antibacterial
poly[Phe<sub>12</sub>-<i>stat</i>-Lys<sub>9</sub>-<i>stat</i>-(Lys-FA)<sub>6</sub>] coronas, which may avoid the
inducement of antibiotic-resistant bacteria and side effects of multidrug
interactions. Furthermore, folic acid is introduced into the vesicle
coronas for potential further applications such as cancer-targeted
drug delivery. Moreover, the amino groups can be further functionalized
when necessary. This low cytotoxic, biocompatible, biodegradable,
and antibacterial vesicle (without antibiotic resistance) may benefit
patients after tumor surgery because it is highly anti-inflammatory,
and it is possible to deliver the anticancer drug to tumor cells simultaneously