Yubin Huang

Hydrogen-Bond-Selective Phase Transfer of Nanoparticles across Liquid/Gel Interfaces

In the swim: Colloidal nanoparticles coated with polylactide (PLA, red) and poly(ethylene glycol) brushes (PEG, black) can transfer from organic to aqueous phases across liquid/liquid or liquid/gel interfaces during degradation of the PLA coating (see picture: first step), which is driven selectively by the hydrogen bonding of the PEG coating with the aqueous phase (second step).

Poly(ethylene glycol)-conjugated human serum albumin including iron porphyrins : Surface modification improves the O2-transporting ability

Artificial O2-carrying hemoprotein composed of human serum albumin including tetrakis(o-amidophenyl)porphinatoiron(II) (Fe4P or Fe3P) [HSA-FeXP] has been modified by maleimide- or succinimide-terminated poly(ethylene glycol) (PEG), and the formed PEG bioconjugates have been physicochemically characterized. 2-Iminothiolane (IMT) reacted with the amino groups of Lys to create active thiol groups, which bind to alpha-maleimide-omega-methoxy PEG [Mw: 2-kDa (PEG(M2)), 5-kDa (PEG(M5))]. On the other hand, alpha-succinimidyl-omega-methoxy PEG [Mw: 2-kDa (PEG(S2)), 5-kDa (PEG(S5))] directly binds to Lys residues. MALDI-TOF MS of the PEG-conjugated HSA-FeXP showed distinct molecular ion peaks, which provide an accurate number of the PEG chains. In the case of PEG(MY)(HSA-FeXP), the spectroscopic assay of the thiol groups also provided the mean of the binding numbers of the polymers, and the degree of the modification was controlled by the ratio of [IMT]/[HSA]. The viscosity and colloid osmotic pressures of the 2-kDa PEG conjugates (phosphate-buffered saline solution, [HSA] = 5 g dL(-1)) were almost the same as that of the nonmodified one, whereas the 5-kDa PEG binding increased the rheological parameters. The presence of flexible polymers on the HSA surface retarded the association reaction of O2 to FeXP and stabilized the oxygenated complex. Furthermore, PEG(MY)(HSA-FeXP) exhibited a long circulation lifetime of FeXP in rats (13-16 h). On the basis of these results, it can be concluded that the surface modification of HSA-FeXP by PEG has improved its comprehensive O2-transporting ability. In particular the PEG(MY)(HSA-FeXP) solution could be a promising material for entirely synthetic O2-carrying plasma expander as a red cell substitute.

Enhanced radiation response of a solid tumor with the artificial oxygen carrier 'albumin-heme'

Tumor‐cell hypoxia is one of the main factors inducing radioresistance. Enhanced tumor oxygenation has previously been achieved in an animal model using the synthetic heme‐based oxygen carrier ‘albumin‐heme’ (recombinant human serum albumin‐Fe cyclohexanoil heme; rHSA‐FeP). The present study was done to determine whether rHSA‐FeP enhances the radiation response in an experimental tumor model. Male Donryu rats and LY80, a variant of the syngenic liver ascites tumor, were used. A total of 1 × 106 cells were injected into the subfascial tissue of the right thigh. The rats were divided randomly into five groups: sham (tumor implantation and sham operation); rHSA‐FeP; irradiation; rHSA + irradiation; and rHSA‐FeP + irradiation. Six days after, under general anesthesia, intra‐arterial administration of 10 mL/kg of either 5% rHSA solution or oxygenated rHSA‐FeP solution at 2.5 mL/min was done and a dose of 20 Gy was given. There were significant differences in tumor growth between the sham and irradiation groups, and between the sham and rHSA‐FeP + irradiation groups. Tumor growth delay was observed and differences were significant between the sham and irradiation groups, and between the irradiation and rHSA‐FeP + irradiation groups. In the present study, rHSA‐FeP itself had a slight effect on tumor growth without irradiation. Enhancing the effect of rHSA‐FeP on the radiation response is responsible in part for the oxygen‐carrying property of rHSA‐FeP. In conclusion, rHSA‐FeP is a candidate radiation‐enhancing drug. Arterial infusion of rHSA‐FeP may serve as a local oxygenation method that enhances the radiation effect. (Cancer Sci 2008; 99: 1274–1278)

Safety and efficacy of hemoglobin-vesicles and albumin-hemes

Summary Keio University and Waseda University have worked together on artificial O2 carrier research for 20 years in close cooperation. Two candidate materials have been selected from the viewpoints of safety, efficacy, and cost performance. One is Hemoglobin-vesicles (HbV) and the other is albumin-heme (rHSA-heme). This chapter summarizes our video presentation that introduced the recent results of our research into HbV and rHSA-heme.

Complete Deoxygenation from a Hemoglobin Solution by an Electrochemical Method and Heat Treatment for Virus Inactivation

Hemoglobin (Hb) has been widely studied as a raw material for various types of oxygen carriers. In the purification of Hb from red blood cells including virus inactivation and denaturation of other proteins and the long‐term storage of Hb vesicles (HbV), a deoxygenation process is one of the important processes because of the high stability of deoxygenated Hb to heating and metHb formation. Though an oxygenated Hb solution can be deoxygenated with an artificial lung, it is difficult to reduce the oxygen partial pressure of the Hb solution to less than 10 Torr. We developed an electrochemical system for complete deoxygenation of the Hb solution at the cathode compartment using hydrogen containing nitrogen gas at the anode compartment. Oxygen in the Hb solution was reduced to OH− at the cathode compartment within several minutes at a potential value of −1.67 V and was finally converted to water by neutralization with H+ from the anode in the whole system. The resulting completely deoxygenated Hb could tolerate heat treatment at 62 °C for 10 h with no denaturation of deoxygenated Hb. The metHb formation rate of reoxygenated Hb at 37 °C was not changed after heat treatment. Furthermore, vesicular stomatitis virus (VSV) could be inactivated at an inactivation degree of more than 5.96 log by heat treatment.

Safety evaluation of an artificial O2 carrier as a red blood cell substitute by blood biochemical tests and histopathology observations.

Recombinant human serum albumin (rHSA) incorporating synthetic heme with a covalently linked proximal base (albumin-heme [rHSA-heme]) is an artificial O2 carrier that can transport O2 like hemoglobin does in the blood stream. To evaluate the clinical safety of this compound, 20% and 40% exchange transfusions with rHSA-heme into anesthetized rats were followed by blood biochemical tests and histopathologic observations for 7 days. In the 20% rHSA-heme group, a total of 30 analytes by blood biochemical tests showed almost the same values as those observed in the reference 20% rHSA group. Although some abnormal values for liver parameters were found in the 40% rHSA-heme group, they returned to normal after 7 days. Histopathologic observations indicated that the administration of rHSA-heme in a volume of 20% total blood volume did not produce any negative side effects on the vital organs.