Silencing the antigenic response of red blood cells (RBCs) is a prerequisite toward the development of universal blood transfusion. Using a two-dimensional (2D) model whereby nonfixed RBCs are adsorbed on a human fibronectin (HFN)-coated surface, we demonstrate that the layer-by-layer (LbL) assembly technique of biocompatible polyelectrolytes can be employed to achieve the immunocamouflage of RBCs against the Anti-A antibody while maintaining the integrity and viability of the cells. The multilayered film consisted of a protecting shell (P-shell), containing five bilayers of chitosan-graft-phosphorylcholine (CH-PC) and sodium hyaluronate (HA), covered by a camouflage shell (C-shell) made up of five bilayers of poly-(L-lysine)-graft-poly(ethylene glycol) (PLL-PEG) and alginate (AL). Control experiments in which RBCs were coated by (CH-PC/HA)(10) bilayers indicated that the two polyelectrolytes alone did not prevent immunorecognition. The LbL film formation on RBCs and model substrates was monitored by quartz crystal microbalance with dissipation factor (QCM-D) and analyzed through zeta-potential measurements, atomic force microscopy (AFM), and optical microscopy. Antibody interaction with the coated RBCs was investigated by QCM-D, fluorescence microscopy, and hemolysis assays. Results from these measurements demonstrated that the hybrid LbL system built-up with different sets of polyelectrolytes was able to protect the RBCs from hemolysis and recognition by the Anti-A antibody.

A series of novel biodegradable random copolymers of 5‐benzyloxy‐1,3‐dioxan‐2‐one (5‐benzyloxy‐trimethylene carbonate, BTMC) and glycolide were synthesized by ring‐opening polymerization. The copolymers were characterized by nuclear magnetic resonance (NMR) spectroscopy and gel permeation chromatography (GPC). The incorporation of BTMC units into the copolymer chains results in good solubility of the polymers in common solvents. The in vitro degradation rate can be tailored by adjusting the composition of the copolymers.The in vitro degradation of the homopolymers and poly(BTMC‐co‐GA) copolymers.magnified imageThe in vitro degradation of the homopolymers and poly(BTMC‐co‐GA) copolymers.

A series of star poly(epsilon-caprolactone)s (PCL) with dendritic cores, PAMAM-PCLs, were synthesized through the ring-opening polymerization of epsilon-caprolactone (CL) initiated by poly(amidoamine) dendrimer (PAMAM-OH). By controlling the feed ratio of the macroinitiator PAMAM-OH to the monomer CL, the star polymers with different branch lengths and properties can be obtained. The successful incorporation of PCL sequences onto the PAMAM-OH core was verified by FTIR, 1H NMR, and combined size-exclusion chromatography and multiangle laser light scattering analysis. The in vitro degradation of PAMAM-PCLs was investigated. The results show the hydrolytic degradation rate increases with increasing content of hydrophilic PAMAM-OH core. While the enzymatic degradation rate is affected by two competitive factors, the catalytic effect of Pseudomonas cepacia lipase on the degradation of PCL branches and the hydrophilicity that depends on the polymer composition. Using the PAMAM-PCLs with different molecular weights, the microsphere drug delivery systems with submicron sizes were fabricated using an "ultrasonic assisted precipitation method." The in vitro drug release from these microspheres was investigated.

A series of biodegradable amphiphilic graft polymers were successfully synthesized by grafting poly(epsilon-caprolactone) (PCL) sequences onto a water-soluble poly-alpha,beta-[N-(2-hydroxyethyl)-L-aspartamide] (PHEA) backbone. The graft copolymers were prepared through the ring-opening polymerization of epsilon-caprolactone (CL) initiated by the macroinitiator PHEA with pendant hydroxyl groups without adding any catalyst. By controlling the feed ratio of the macroinitiator to the monomer, the copolymers with different branch lengths and properties can be obtained. The successful grafting of PCL sequences onto the PHEA backbone was verified by FTIR, 1H NMR, and combined size-exclusion chromatography and multiangle laser light scattering (SEC-MALLS) analysis. The hydrolytic degradation and enzymatic degradation of these graft copolymers were investigated. The results show the hydrolytic degradation rate increases with increasing content of hydrophilic PHEA backbone. While the enzymatic degradation rate is affected by two competitive factors, the catalytic effect of Pseudomonas cepacia lipase on the degradation of PCL branches and the hydrophilicity which depends on the copolymer composition. In situ observation of the degradation under polarizing light microscope (PLM) demonstrates the different degradation rates of different regions in the polymer samples.

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