Effect of physical exercise on the efficacy of mitoxantrone-loaded nanoparticles in treating early breast cancer / 生物医学工程学杂志

Physical exercise of moderate intensity is becoming readily accepted as an adjunct therapy to enhance curative effects of chemotherapy in patients with breast cancer. In this study, we investigated the putative effect of physical exercise on inhibition of breast cancer and the possible mechanism therein involoved. Balb/c female mice were transplanted with BCAP-37 breast xenografts and randomly assigned to four groups: (a) saline control, (b) exercise-only, (c) DHAQ-loaded NPs, (d) exercise + DHAQ-loaded NPs. The mice in exercise groups performed progressive wheel running up to 15 m/min for 30 minutes, 6 d/wk for 4 weeks. Tumor growth delay was significantly longer in the DHAQ-loaded NPs group and the exercise + DHAQ-loaded NPs groups compared with that in the control group (P < 0.05; P < 0.01, respectively). Tumor volume and the value of hemoglobin (HGB) showed significant difference between the DHAQ-loaded NPs and exercise + DHAQ-loaded NPs groups (P < 0.05), suggesting that physical exercise of moderate intensity can significantly induce an influence of DHAQ-loaded NPs on delay in tumor growth, and can enhance the anti-tumor efficacy of DHAQ-loaded PLA-PLL-RGD NPs. It is a contributor to adjuvant therapy for breast cancer.

Development of nanohydroxyapatite composites as bone grafting materials / 生物医学工程学杂志

Hydroxyapatite (HA) is one of ideal materials for bone substitutions due to its intrinsic biocompatibility. However, its relatively poor mechanical properties such as brittleness and low strength have hindered its use in high-load applications. Biotic bones themselves are nanocomposites mainly composed of nanohydroxyapatite (n-HA) and collagen. From biomimetic point of view, nanocomposites of HA could potentially improve both biocompatibility and mechanical properties of bone grafting materials. Recent progress in this field branched into nanocomposites of HA with nonbiodegradable and biodegradable polymers, the latter including collagen, gelatin, chitosan, polylactides as well as polyanhydrides. In this paper, the preparation, biological reactions and mechanical properties of different nanocomposites are reviewed in detail.

Study on synthesis of physically crosslinked biomedical polyurethane hydrogel / 生物医学工程学杂志

In this study, using ethylene carbonate and ethanolamine, we synthesized a novel diol chain-extender, bis-hydroxylethyl carbomate (EC-AE), which contains carbomate structure. The polyurethanes, PUA25 and PUB25, with different extenders, EC-AE and BDO, were synthesized by one-step polymerization, respectively. Their structures were characterized by using FT-IR and DSC. The results indicated that the microphase separation degree of PUA25 was less than that of PUB25, in other words, the amount of hydrogen bonding between hard segments and soft segments in PUA25 was superior to that in PUB25. And the formation of physically crosslinked hydrogels prepared by PUA25 and PUB25 were studied in detail. It was found that only PUA25 can form hydrogel in situ from solution state by cooling. And this kind of hydrogels showed the transition cycle of "gel-sol-gel" under "cooling-heating-cooling" thermal cycles, respectively. The results suggested that the physically crosslinked polyurethane hydrogels were easily possessed in high degree of phase mixing.

Synthesis and characterization of PEG-segmented polyurethane / 生物医学工程学杂志

PEG (Mn = 1000)-segmented polyurethanes, with hard segment percentage of 40%, 50% and 55% and named PU-H40, PU-H50 and PU-H55 respectively, were synthesized by bulk polymerization. The structure of PU was characterized by FTIR, DSC, and GPC. Mechanical properties, water contact angles and water vapor transmit rate(WVTR) were also tested. FTIR and DSC showed that the degree of microphase separation increased with the hard content. Mechanical test showed the tensile strength of PU-H50 to be 25 MPa, the highest tensile strength of the PU series. By the use of PEG as soft segment, the surface hydrophilicity of the materials increased dramatically. Owing to its high degree of microphase separation and the mobility of soft segment, the water contact angle of PU-H55 attained to 33 degrees. The WVTRs of PU-H40, PU-H50 and PU-H55 were 789 g/m2/24h, 705 g/m2/24h and 623g/m2/24h respectively. These data suggest that the materials are suitable for fabricating such biomedical articles as surgical gloves, wound dressing and medical protective coating.

Synthesis, characterization and blood compatibility studies of waterproof breathable polyurethanes / 生物医学工程学杂志

Adopting the two-step method and changing the proportion between PEG (Polyethylene glycol) and PTMG (poly (tetrahydrofuran), we used the MDI (4,4'-diphenylmethane diisocyanate) and short chain extender BDO (1,4-butanediol) as hard segment, the PTMG and PEG as soft segment, and hence prepared a series of polyether-based thermoplastic polyurethanes. FTIR showed the structure character of these polyurethanes. The determination of mechanics property and water contact angles revealed their good mechanics properties and hydrophilicity. Blood compatibility was evaluated by hemolysis test and platelet adhesion test, which revealed their good hemocompatibility. So those polyurethanes may be of wide application in the future.

Progress in the studies on hydrogel burn dressings / 生物医学工程学杂志

Synthetic burn dressing remains the central theme for burn dressing development. The advantages and disadvantages of current available dressings were reviewed. As one of the most successful dressings, the hydrogel burn dressing, its combination with other materials and related progress in researches were presented in detail. Finally, the trend in development of synthetic burn dressing was presented.

Insight into surface structure and hemocompatibility of fluorinated poly(ether urethane)s and poly(ether urethane)s blends / 生物医学工程学杂志

It has been well known that fluorinated polyurethanes exhibit unique low surface energy, biocompatibility, biostability and nonsticking behavior. Consequently, these polymers have attracted considerable interest. In this study, the effect of various concentrations of fluorinated polyurethanes in the polyurethanes on the surface structures of the blends and their hemocompatibility were investigated by XPS, AFM, contact angle and platelet adhesion. It was found that the high concentration fluorine on the outer surfaces of the blends obtained with the low concentration of fluorinated polyurethanes (F: 0.342 wt%) in the blends was the same as that of the fluorinated poly(ether urethane)s, and all of the blends and the fluorinated poly(ether urethane)s had good hemocompatibility, compared with poly(ether urethane)s. The polymer blends and fluorinated poly(ether urethane)s suppressed platelet adhesion due to their high hydrophobicity and low surface tension. The XPS, AMF and contact angle results indicated that the high hydrophobicity of outer surface of the polyurethane blends is independent of the fluorinated polyurethanes content in the polymer blends but related to the concentration of the CF3 groups because the lower critical surface tensions and higher contact angle of many fluorinated surfaces reflect the concentration of CF3 groups.

Synthesis, characterization and blood compatibility studies of biomedical aliphatic polyurethanes / 生物医学工程学杂志

The one-step method was adopted in this study to synthesize aliphatic polyurethane with 4,4-methylene dicyclohexyl diisocyanate(HMDI), 1,4-butanediol (BDO) and poly (tetrahydrofuran) (PTMG). The tests conducted on this material were: FIR spectrum, mechanical properties test, water contact angles test, hemolysis test and platelet adhesion test. Results showed that this material has a good tensile strength up to 30 Mpa, similar to aromaphatic polyurethane. But its tensile elongation, tensile permanent change, hydrophility are better than those of aromaphatic polyurethane. The hemolysis test and platelet adhesion test showed that it has good blood compatibility.

Applications of biodegradable polyurethane in medical field / 生物医学工程学杂志

The use of biodegradable polyurethane as medical appliance has rapidly become a fascinating new field of research in biomedical science. Tremendous progress has been made in this area during the last years. Applications of these materials in the field of organic repairing, tissue engineering and drug-controlled delivery system were reviewed. These new type materials possess excellent properties, such as good biocompatibility and mechanical strength, facile formation and inexpensive, so it can be expected to find wide application in the medical treatment in future.

The advance of research for biocompatibility of medical polyurethanes / 生物医学工程学杂志

Polyurethanes are popularly used in cardiovascular and other biomedical fields due to their good biocompatibility as well as mechanical properties. But they are subject to biodegradation in vivo for a long time, and cause inflammation, so improving the biocompatibility of medical polyurethanes is an important subject of biomaterials. Recent researches have focused on biological modelling of biomaterials for improving the biocompatibility of polyurethanes. This paper reviews two main methods for improving biocompatibility of polyurethanes-endothelial cells seeding and mimic biomembrane (phospholipid surface), and summarizes the main procedures and questions of these two methods.

The study of photochemical immobilization of urease on polyether sulfone film surface / 生物医学工程学杂志

A new method of using photoactivable ester with azido group was described to immobilize urease on polyether sulfone(PES) film surface. The effects of photoactive enzyme concentration, temperature, pH, irradiation time on the activity of immobilized urease were investigated. Reused times and storage stability were also studied. The results showed that the surface concentration of urease immobilized on PES surface was about 0.33 mg/cm2. When the irradiation time was 5 minutes, the relative activity of immobilized urease was the highest and the activity increased with the increase of the concentration of photoactive urease solution. The optimum pH and temperature of immobilized urease were 7 and 50 degrees C respectively. The relative activity of immobilized urease was stable (50%) after 12 times reused at 50 degrees C.

Study on blood compatibility of polyurethanes for catheters / 生物医学工程学杂志

In this article, the blood compatibility of polyurethanes (PUs) made by ourselves for catheters is studied by hemolysis test, platelets adhesion test, kinetic thrombus time test and dynamic clot formation. The results showed that these PUs all have excellent blood compatibility. Among these PUs, H50-100 and H60-100 have best blood compatibility. Additionally, the relationship between the structure and blood compatibility is discussed.