Oxygen Carrier Based on Hemoglobin/Poly(l-lysine)-block-poly(l-phenylalanine) Vesicles

Abstract

An oxygen carrier was prepared by encapsulating carbonylated hemoglobin (CO-Hb) molecules into polypeptide vesicles made from poly(L-lysine)-block-poly(L-phenylalanine) (PLL-b-PPA) diblock copolymers in aqueous medium at pH 5.8. The encapsulation was confirmed by confocal laser scanning microscopy (CLSM). The morphology and size of the vesicles were studied by field-emission scanning electron microscopy (ESEM). They had a spherical shape with a mean diameter of about 4 to 5 microm. The encapsulation efficiency of hemoglobin was 40 wt %, and the hemoglobin content in the vesicles was 32 wt %. The CO-Hb encapsulated in the PLL-b-PPA vesicles was more stable than free CO-Hb under ambient conditions. In the presence of a O(2) atmosphere, the CO-Hb in the vesicle could be converted into oxygen-binding hemoglobin (O(2)-Hb) under irradiation of visible light for 2 h. Therefore, the CO-Hb/PLL-b-PPA vesicles are expected to be used as red blood cell substitutes.

Dextran-based thermo-responsive hemoglobin–polymer conjugates with oxygen-carrying capacity

“…However, the CO molecule bound to Hb could be displaced by O 2 if its concentration was high enough. 15,17 As shown in Fig. 6, the met-Hb in ferric state could be transformed into the ferrous CO-Hb in the presence of ascorbic acid under carbon monoxide atmosphere, accompanied with a red shi of the Soret band from 405 nm to 419 nm.…”

Synthesis of Hemoglobin Conjugated Polymeric Micelle: A ZnPc Carrier with Oxygen Self-Compensating Ability for Photodynamic Therapy

“…33 Thereinto, CO has about 200 times the affinity of O 2 for Hb, and CO only can be displaced by O 2 under high oxygen concentration. 24,40 Therefore, met-Hb conjugated micelles were first reduced and protected by CO in the present work, allowing for easy storage and further processing. The state conversion could be monitored via UV− vis spectrophotometry.…”

“…29,30 For example, poly(L-lysine)-block-poly(L-phenylalanine) (PLL-b-PPA) diblock copolymers were self-assembled into polypeptide vesicles to encapsulate Hb, which were proven to be more stable than free Hb. 24 Besides physically encapsulated Hb, the chemical conjugation method was also proved to improve the stability of Hb in HBOC. Huang et al synthesized MPEG−PMPC−PLA copolymers to conjugate azide-functionalized Hb on PMPC segments using click chemistry to form Hb-bearing nanomicelles, which showed appropriate stability and oxygen carrying capacity.…”

Synthesis and Self-Assembly of Well-Defined Block Copolypeptides via Controlled NCA Polymerization

“…K x PBLG y K x ) triblock copolypeptides, where the helical PBLG core favors vesicle formation [90]. Jing and coworkers prepared vesicle forming lysine-phenylalanine (K x F y ) copolypeptides, containing α-helical phenylalanine segments [91]. These vesicles were also found to be useful in encapsulating hemoglobin and acting as oxygen carriers.…”