Effects of surfactant and solvent on the encapsulation efficiency and size in using double emulsion method for preparing bovine hemoglobin loaded nanoparticles as blood substitutes / 生物医学工程学杂志

On the basis of previous researches, we have prepared Bovine hemoglobin-loaded nanoparticles (HbP), using the double emulsion method. More mild dispersing treatment was employed during the primary and secondary emulsion; over 97% encapsulation efficiency (EE%) and an average size about 286 nm were achieved by using surfactants, screening solvents, as well as avoiding the traditional strong dispersing process. The value of Hydrophile-lipophile balance in oil phase exerted a significant effect on EE% and led to higher EE% when matched with the surfactants in outer aqueous phase. When compared with the sole solvent Span80, the mixed surfactants such as Poloxemer188/Span80 stabilized the emulsion more efficiently and increased the EE%. The higher concentration of surfactants resulted in higher EE% and narrower size distribution. But over some amount, the surfactants had no significant effect on EE%, resulting in larger size and polydispersity index (PDI). The appropriate removal rate of solvents contributes to higher EE%, smaller size and PDI.

Progress of researches on drug-loaded nanoparticles / 生物医学工程学杂志

The progress of researches on drug-loaded nanoparticles was summarized in this review. The major emphasis was laid on the selection of wall polymers, technology of preparation, surface modification, investigation of release in vitro and biocompatibility evaluation. Additionally, we envisioned a perspective regarding the development in this field. With the development of synthesis of biodegradable polymer, with the appearance of novel equipment, and with the deep-going studies on modification of nanoparticles surface method, on fabrication of nanoparticles art as well as on evaluation of drug release and reaction between drug and organ, further researches in this field will open up the way to applications of drug-loaded nanoparticles in larger field.

Preparation of hemoglobin-loaded nanoparticles and safety evaluation in vitro and in vivo / 生物医学工程学杂志

Hemoglobin-loaded nano-sized particles with oxygen carrying capacity were prepared. All experiments were performed using biodegradable polymer poly (polyepsilon-caprolactone) (PCL) as matrix polymer. Optimized preparation parameters led to nanoparticles with well-defined characteristics such as size <200 nm, P50 27 mmHg and high encapsulation efficiency up to 99.4%. The results of in vitro and vivo studies suggested that Hb-loaded particles did not activate complements. After the nanoparticles suspension was injected into the mice via tail vein, the particles did not cause significant changes in total platelet counts. Apparently, the hemoglobin-loaded nanoparticles can serve as a potential candidate in substitution for red cells.

A nondestructive method to measure the oxygen binding and releasing properties of biodegradable polymers microcapsules intented for blood substitutes / 生物医学工程学杂志

P50 is an important parameter reflecting the binding and releasing oxygen properties of blood substitutes. In this study, based on the strong penetrating property of near infrared light and the mechanism involved in the pulsatile oxygen meter in clinic as well as on the ability for penetrating biodegradable polymers and detecting bovine hemoglobin encapsulated within the microcapsules, we have made an airproof and equilibrium apparatus to measure oxygen saturation and oxygen partial pressure. Subsequently, we have obtained the oxygen dissociation curve and P50 of the microcapsules loaded bovine hemoglobin in the light of oxyHemoglobin and deoxyHemoglobin with different spectrum in the near infrared region. The above-mentioned apparatus and method are not destructive to the microcapsules, and the process is simple and nondestructive. So it is practical to take in-situ measurements of the oxygen binding and releasing property of biodegradable polymer microcapsules intented for the blood substitute.

Preparation of bovine hemoglobin-loaded nanoparticles used as blood substitutes and establishment of reduction system / 生物医学工程学杂志

Bovine Hb-loaded nanoparticles with modulated size of pores, for use as blood substitutes, were prepared and a nonenzymatic reduction system including two-step-reduction and process optimization was established to control the metHb level in the present study. After the first-step-reduction procedure was performed, the raw BHb, being oxidized severely, was encapsulated to form nanoparticles by the modified double emulsion method. The binary solvent of dichloromethane (DCM) and acetonitrile (Aci) showed properties such as minimizing Hb oxidation and enlarging the pores of nanopartilces. Based on the size of pores o f nanoparticles evaluated by the diffusion of various substances wi thdifferent molecular weights, reducing agents such as ascorbic acid and glutathione present in the plasma were selected to perform the second-step-reduction, i. e. to further reduce the metHb in nanoparticles. The metHb level was reduced from over 90% in the raw materials to 1.25% by the two-step-reduction and controlled preparation; this is near the level of native blood, possessing the ability of carrying/releasing oxygen.

Study on mass transfer behavior of hemoglobin-based nanocapsule surface / 生物医学工程学杂志

Three dimensional structure of the surface is an important factor that influences the mass transfer behavior of hemoglobin-based nanocapsule surface. In this paper, the modified double emulsion method was used to fabricate the blood substitute of hemoglobin-based nanocapsules, and with the use of different molecular weight of PEG as probes, the effects of different technical conditions (such as primary emulsion, double emulsion, polymer, solvent, et al) in the processing on the three dimensional structure of the nanocapsule surface were investigated in details. Researches indicated that the water-soluable solvent, such as ethyl acetate and acetone could effectively modulate the pore size of the nanocapsule surface. With the increasing of the ratio of water-soluble solvent, the pore size of the nanocapsules firstly increased and then decreased. The increasing of the extra-water volume, the prolongation of the solvent evaporation time, and the improvement of the stirring speed resulted in a bigger pore size, but the increasing of the solvent volume and PEG polymer could reduce the pore size of nanocapsule surface.

Mechanical properties and crystallization behaviors of nanostructured-Zno/PET in-situ composites.

In this paper, the mechanical properties and the crystallization behaviors of nano-ZnO particle reinforced PET (ZnO/PET) composite were investigated in order to verify the possibility of industrial application of ZnO/PET. The addition of nano-ZnO particle (nZnOp) improves the tensile strength and elongation of PET, which reach their maximums at 2 wt% nZnOp addition. The enhancement of tensile properties of ZnO/PET composite indicates the improvement in the crystallinity of PET because of the constancy in molecular weight of PET with and without nZnOp addition. Whereas the impact strength of PET decreases with the nZnO, addition, except the nZnOp addition around 2 wt%, at which the highest value has been achieved among the pure PET and composites. And according to the DSC and XRD results, 2 wt% ZnO/PET composite has the highest crystallinity and among pure PET and composites. Furthermore, by combining both DSC and XRD results, the nZnOp addition was found effective in increasing the crystallinity of PET matrix as well as possibly capable of changing the crystallization form of PET. 2 wt% ZnO/PET composite could be a promising upgrade of PET due to the considerable improvement in mechanical properties.