Enhanced mechanical properties and in vitro cell response of surface mechanical attrition treated pure titanium

Surface mechanical attrition treatment (SMAT) was used to fabricate nanocrystalline surface layers on the commercial purity titanium. X-ray diffraction and transmission electron microscopy results indicate that the top layer contained nanograins. Enhanced strength and microhardness were achieved due to the surface nanostructure. Cell culture tests have shown a greater adhered cell density and more extensively spreading morphologies of Saos-2 cells on the SMAT substrates compared to those on the as-received Ti counterparts. Enhanced cell viability and cell cycle were also achieved on the SMAT Ti substrates. These could be attributed to the nanostructure grains with the increased surface hydrophilicity and roughness on the SMAT Ti.     

The effect of Nb addition on mechanical properties, corrosion behavior, and metal-ion release of ZrAlCuNi bulk metallic glasses in artificial body fluid

Bulk metallic glasses (BMGs) of Zr(65 - x)Nb(x)- Cu(17.5)Ni(10)Al(7.5) with Nb = 0, 2, and 5 at % were prepared by copper mold casting. Compression tests reveal that the two BMGs containing Nb exhibited superior strength and plasticity to the base alloy. The corrosion behavior of the alloys obtained was investigated in artificial body fluid by electrochemical measurements. It was found that the addition of Nb significantly enhanced the corrosion resistance of the Zr-based BMG, as indicated by a remarkable increase in corrosion potential and pitting potential. XPS analysis revealed that the passive film formed after anodic polarization was enriched in aluminum oxide and depleted in phosphate ions for the BMGs containing Nb, which accounts for the improvement of corrosion resistance. On the other hand, metal-ion release of different BMGs were determined in PPb (ng/mL) level with inductively coupled plasma mass spectrometry (ICP-MS) after being immersed in artificial body fluid at 37 degrees C for 20 days. It was found that the addition of Nb considerably reduced the ion release of all kinds of metals of the base system. This is probably attributed to the promoting effect of Nb on a rapid formation of highly protective film.     

The effect of Pt and Pd alloying additions on the corrosion behavior of titanium in fluoride-containing environments

In this study, we examined the corrosion behaviors of pure titanium, the alloys Ti-6Al-4V and Ti-6Al-7Nb, and the new experimental alloys Ti-Pt and Ti-Pd using anodic polarization and corrosion potential measurements in an environment containing fluoride. Before and after immersion in the test solutions, we made observations using a scanning electron microscope. The test solutions included an artificial saliva containing 0.2% NaF (corresponding to 905 ppm F) and an artificial saliva with a low concentration of oxygen. Although the surfaces of the Ti-Pt and Ti-Pd alloys were not affected by an acidic environment containing fluoride, the surfaces of the pure titanium, the Ti-6Al-4V alloy, and the Ti-6Al-7Nb alloy were markedly roughened by corrosion. The surfaces of the pure titanium, the Ti-6Al-4V alloy, and the Ti-6Al-7Nb alloy were microscopically damaged by corrosion when they were immersed in the solution containing a low concentration of dissolved oxygen, even with a fluoride concentration included in the commercial dentifrices. In this situation, however, the surfaces of the new Ti-Pt and Ti-Pd alloys were not affected. These alloys are expected to be of use in dental work as new titanium alloys with high corrosion resistances.     

Processing, properties, and in vitro bioactivity of polysulfone-bioactive glass composites

The mismatch between the mechanical properties of bioceramics and natural tissue has restricted in several cases a wider application of ceramics in medical and dental fields. To overcome this problem, polymer matrix composites can be designed to combine bioactive properties of some bioceramics with the superior mechanical properties of some engineering plastics. In this work, polymer particulate composites composed of a high mechanical-property polymer and bioactive glass particles were produced and both the in vitro bioactivity and properties of the system were investigated. Composites with different volume fraction and particle size were prepared. In vitro tests showed that hydroxy-carbonate-apatite can be deposited on the surface of a composite as early as 20 h in a simulated body fluid. Ionic evolution from a composite with 40% volume fraction of particles was demonstrated to be similar to bulk bioactive glasses. The mechanical properties of some of the obtained composites had values comparable with the ones reported for bone. Moreover, a physical model based on dynamical mechanical tests showed evidences that the interface of the composite was aiding in the stress transfer process.     

Examination of surface properties and in vitro biological performance of amorphous diamond-like carbon-coated polyurethane

Despite the emerging use of diamond-like carbon (DLC) as a coating for medical devices, few studies have examined the resistance of DLC coatings onto medical polymers to both microbial adherence and encrustation. In this study, amorphous DLC of a range of refractive indexes (1.7-1.9) and thicknesses (100-600 nm) was deposited onto polyurethane, a model polymer, and the resistance to microbial adherence (Escherichia coli; clinical isolate) and encrustation examined using in vitro models. In comparison to the native polymer, the advancing and receding contact angles of DLC-coated polyurethane were lower, indicating greater hydrophilic properties. No relationship was observed between refractive index, thickness, and advancing contact angle, as determined using multiple correlation analysis. The resistances of the various DLC-coated polyurethane films to encrustation and microbial adherence were significantly greater than that to polyurethane; however, there were individual differences between the resistances of the various DLC coatings. In general, increasing the refractive index of the coatings (100 nm thickness) decreased the resistance of the films to both hydroxyapatite and struvite encrustation and to microbial adherence. Films of lower thicknesses (100 and 200 nm; of defined refractive index, 1.8), exhibited the greatest resistance to encrustation and to microbial adherence. In conclusion, this study has uniquely illustrated both the microbial antiadherence properties and resistance to urinary encrustation of DLC-coated polyurethane. The resistances to encrustation and microbial adherence were substantial, and in light of this, it is suggested that DLC coatings of low thickness and refractive index show particular promise as coatings of polymeric medical devices.     

Manufacturing, mechanical characterization, and in vitro performance of bioactive glass 13-93 fibers

Fibers were manufactured from the bioactive glass 13-93 by melt spinning. The fibers were further characterized by measuring their tensile and flexural strength, and their in vitro performance was characterized by immersing them in simulated body fluid, which analyzed changes in their mass, their flexural strength, and surface reactions. The strength of glass fibers is highly dependent on fiber diameter, test method, and possible surface flaws, for example, cracks due to abrasion. In this study, the thinnest fibers (diameter between 24 and 33 microm) possessed the highest average tensile strength of 861 MPa. The flexural strength was initially 1353.5 MPa and it remained at that level for 2 weeks. The Weibull modulus for both tensile and flexural strength values was initially about 2.1. The flexural strength started to decrease and was only approximately 20% of the initial strength after 5 weeks. During the weeks 5-40, only a slight decrease was detected. The flexural modulus decreased steadily from 68 to 40 GPa during this period. The weight of the samples initially decreased due to leaching of ions and further started to increase due to precipitation of calcium phosphate on the fiber surfaces. The mass change of the bioactive glass fibers was dependent on the surface area rather than initial weight of the sample. The compositional analysis of the fiber surface after 24 h and 5 weeks immersion did confirm the initial leaching of ions and later the precipitation of a calcium phosphate layer on the bioactive glass 13-93 fiber surface in vitro.     

Physico-chemical-mechanical and in vitro biological properties of calcium phosphate cements with doped amorphous calcium phosphates

Calcium phosphate cements (CPCs) are successfully used as bone substitutes in dentistry and orthopaedic applications. This study investigated the physico-chemical-mechanical properties of and in vitro biological properties (cell response) of CPCs prepared with amorphous calcium carbonate phosphate (ACCP) doped with magnesium (ACCP-Mg), zinc (ACCp-Zn) or fluoride (ACCP-F) ions. The experimental CPC consisted of alpha-TCP, doped ACCP, and MPCM powders as matrix and biphasic calcium phosphate (BCP) granules. X-ray diffraction analysis showed that the matrix converted to apatite with poor crystallinity (reflecting small crystal size) after setting for 24 h, while BCP remained apparently unchanged. Cements with ACCP-F (F-CPC) had shorter setting times and greater compressive strength compared to cements with ACCP-Mg (Mg-CPC) or ACCP-Zn (Zn-CPC). Scanning electron microscopy (SEM) showed that crystals set on Mg-CPC and Zn-CPC were smaller compared to those on F-CPC. The total porosity of Mg-CPC was greater compared to Zn-CPC or F-CPC. Osteoblast-like cells, MC3T3-E1, remained viable and maintained their ability to express alkaline phosphatase in contact with the CPCs with doped ACCPs.     

Passive mechanical properties of large intestine under in vivo and in vitro compression

This paper presents experimental data obtained from both in vivo and in vitro compression of the large intestine of goat. In vivo experimental data were obtained from compression tests on the large intestine of an anesthetized goat using force-displacement acquisition equipment. In vitro experimental data were also obtained from tissue excised after the in vivo experiments, and two types of data were then compared. The results demonstrated that the stress values had a strong dependence on the compressive rate in the in vivo experiments, although such effect was not distinct in the in vitro experiments. Additionally, at a lower compression rate, the intestinal tissues were found to be stiffer in the in vitro experiments than in the in vivo ones. This paper is a preliminary report on the mechanical properties of the large intestine based on in vivo and in vitro experimental data.     

Adventitia-dependent mechanical properties of brachiocephalic ovine arteries in in vivo and in vitro studies

Aim: An adventitia dependent regulation of the vascular smooth muscle tone has been described. However, if the adventitia plays an active role on arterial wall biomechanical behaviour and functions remains to be established. Our aim was to characterize the influence of adventitia on arterial wall mechanical properties and the arterial conduit and buffer functions. Methods: Ovine brachiocephalic arteries were studied in vivo (n = 8) and in vitro (with null tone) in a circulation mock (n = 8). Isobaric, isoflow and isofrequency studies were performed. In each segment, pressure and diameter waves were assessed before and after adventitia removal. From the arterial stress–strain relationship, we derived the elastic and the viscous modulus. The buffering and conduit functions were calculated using the Kelvin–Voigt's time constant and the inverse of the characteristic impedance, respectively. Results: In in vivo studies arterial diameter decreased after adventitia removal (P < 0.05). Elastic and viscous modulus in in vivo studies were significantly higher in adventitia‐removed arteries, compared with values in intact vessels (P < 0.05). This behaviour was not observed in in vitro experiments. An impairment of buffer and conduit functions was observed in vivo after adventitia removal (P < 0.05), while both functions remain unchanged in in vitro studies (P > 0.05). Conclusions: Arterial wall viscosity and elasticity were influenced by adventitia removal in in vivo studies, possibly by a smooth muscle‐dependent mechanism, since it was not present in in vitro experiments. Adventitia would be involved in a physiological mechanism of arterial wall viscous and elastic properties regulation, that could influence arterial buffering and conduit functions.     

Aging of human fibroblasts in vitro: surface features and behavior of aging WI 38 cells.

WI 38 cells at various in vitro ages and an SV 40 virus tranformed variant were examined by (3)H thymidine autoradiography, time lapse cinematography and scanning electron microscopy. Among normal WI 38 cells it was shown that htere was a good correlation between cellular morphology, behavior, and the ability to incorporate (3)H thymidine. Small, elongate spindle-shaped cells were usually both active incorporators of (3)H thymidine, as determined autoradiographically, and dividers as determined by time lapse cinematography; larger, more spread out cells tended to be nondividers. The proportion of large, nondividing cells increased with increasing in vitro age and was correlated with changes in cell surface and behavior. Transformed WI 38 cells exhibited no such changes as a function of age. Results support the thesis that in vitro aging reflects the inability of individual cells to undertake DNA synthesis and to complete division, but nondividers continue to enlarge and unusual sizes and shapes are attained. Associated with these aging changes were conspicuous alterations in cellular curface features and behavior.     

Maintaining dimensions and mechanical properties of ionically crosslinked alginate hydrogel scaffolds in vitro

Ionically crosslinked alginate hydrogels are attractive scaffolds because of their biocompatibility and mild gelation reaction that allows for gentle cell incorporation. However, the instability of ionically crosslinked hydrogels in an aqueous environment is a challenge that limits their application. This report presents a novel method to control the dimensions and mechanical properties of ionically crosslinked hydrogels via control of the ionic concentration of the medium. Homogeneous calcium-alginate gels were incubated in physiological saline baths adjusted to specific calcium ion concentrations. Swelling and shrinking occurred at low and high ionic concentrations of the medium, respectively, while an "optimal" intermediate calcium ion concentration of the medium was found to maintain original size and shape of the hydrogel. This optimal calcium ion concentration was found to be a function of crosslinking density and polymer concentration of the hydrogel and chemical composition of the alginate. The effects of optimal and high calcium ion concentrations of the medium on swelling behavior, calcium content, dry weight, and mechanical properties of the immersed hydrogels were investigated. It was found that the resulting hydrogel composition and mechanical properties depended on not only the calcium concentration of the medium, but also the crosslinking density and polymer concentration of the gel. In an 8-week experiment, controlled dimensions and mechanical properties of alginate gels in an aqueous environment were demonstrated. This new technique significantly enhances the potential of alginate hydrogels for tissue engineering and other biomedical applications.     

Three-dimensional,bioactive, biodegradable,polymer-bioactive glass composite scaffolds with improved mechanical properties support collagen synthesis and mineralization of human osteoblast-like cells in vitro

In the past decade, tissue engineering-based bone grafting has emerged as a viable alternative to biological and synthetic grafts. The biomaterial component is a critical determinant of the ultimate success of the tissue-engineered graft. Because no single existing material possesses all the necessary properties required in an ideal bone graft, our approach has been to develop a three dimensional (3-D), porous composite of polylactide-co-glycolide (PLAGA) and 45S5 bioactive glass (BG) that is biodegradable, bioactive, and suitable as a scaffold for bone tissue engineering (PLAGA-BG composite). The objectives of this study were to examine the mechanical properties of a PLAGA-BG matrix, to evaluate the response of human osteoblast-like cells to the PLAGA-BG composite, and to evaluate the ability of the composite to form a surface calcium phosphate layer in vitro. Structural and mechanical properties of PLAGA-BG were measured, and the formation of a surface calcium phosphate layer was evaluated by surface analysis methods. The growth and differentiation of human osteoblast-like cells on PLAGA-BG were also examined. A hypothesis was that the combination of PLAGA with BG would result in a biocompatible and bioactive composite, capable of supporting osteoblast adhesion, growth and differentiation, with mechanical properties superior to PLAGA alone. The addition of bioactive glass granules to the PLAGA matrix resulted in a structure with higher compressive modulus than PLAGA alone. Moreover, the PLAGA-BA composite was found to be a bioactive material, as it formed surface calcium phosphate deposits in a simulated body fluid (SBF), and in the presence of cells and serum proteins. The composite supported osteoblast-like morphology, stained positively for alkaline phosphatase, and supported higher levels of Type I collagen synthesis than tissue culture polystyrene controls. We have successfully developed a degradable, porous, polymer bioactive glass composite possessing improved mechanical properties and osteointegrative potential compared to degradable polymers of poly(lactic acid-glycolic acid) alone. Future work will focus on the optimization of the composite scaffold for bone tissue-engineering applications and the evaluation of the 3-D composite in an in vivo model.     

Influence of porosity on mechanical properties and in vivo response of Ti6Al4V implants

Metallic biomaterials are widely used to restore the lost structure and functions of human bone. Due to the large number of joint replacements, there is a growing demand for new and improved orthopedic implants. More specifically, there is a need for novel load-bearing metallic implants with low effective modulus matching that of bone in order to reduce stress shielding and consequently increase the in vivo lifespan of the implant. In this study, we have fabricated porous Ti6Al4V alloy structures, using laser engineered net shaping (LENS?), to demonstrate that advanced manufacturing techniques such as LENS? can be used to fabricate low-modulus, tailored porosity implants with a wide variety of metals/alloys, where the porosity can be designed in areas based on the patient’s need to enhance biological fixation and achieve long-term in vivo stability. The effective modulus of Ti6Al4V alloy structures has been tailored between 7 and 60 GPa and porous Ti alloy structures containing 23–32 vol.% porosity showed modulus equivalent to human cortical bone. In vivo behavior of porous Ti6Al4V alloy samples in male Sprague–Dawley rats for 16 weeks demonstrated a significant increase in calcium within the implants, indicating excellent biological tissue ingrowth through interconnected porosity. In vivo results also showed that total amount of porosity plays an important role in tissue ingrowth.     

CD40-deficient dendritic cells producing interleukin-10, but not interleukin-12, induce T-cell hyporesponsiveness in vitro and prevent acute allograft rejection.

The induction of an immune response or tolerance is mediated by corresponding subsets of dendritic cells (DC). However, the property of tolerogenic DC is not clear. Recently, we have characterized a population of CD11c+ splenic DC derived from long-term mixed leucocyte culture (LT-MLC), which are able to proliferate upon stimulation and have a strong primary mixed leucocyte reaction (MLR)-stimulating activity in conventional MLR. In this study, we show that, in contrast to the irradiated ones, non-irradiated LT-MLC-derived DC induce polyclonal antigen-specific T-cell hyporesponsiveness when cocultured with allogeneic splenocytes for 3-11 days. The degree of the hyporesponsiveness increased with the length of coculture. Although these DC expressed major histocompatibility complex class II and B7 costimulatory molecules, which are down-regulated during coculture, they expressed very low or undetectable CD40 before and after coculture, respectively. The CD40-deficient DC spontaneously produce interleukin-10 (IL-10), but not IL-12. The skewed balance between IL-10 and IL-12 is associated with their capability to induce T-cell hyporesponsiveness, because a neutralizing antibody to IL-10, exogenous recombinant IL-12 or lipopolysaccharide (LPS) significantly blocked the hyporesponsiveness. Accordingly, infusion of a small number of non-irradiated LT-MLC-derived DC (5x105) significantly prolonged the survival of a vascularized heterotopic murine heart transplant, whereas irradiated DC accelerated graft rejection. These data suggest that CD40-deficient DC producing IL-10, but not IL-12 can induce T-cell hyporesponsiveness in vitro and in vivo.     

Influence of physicochemical reactions of bioactive glass on the behavior and activity of human osteoblasts in vitro

Bioactive glasses are characterized by a bond to bone with a hydroxyl carbonate apatite layer. They enhance bone tissue formation and for this purpose are used in orthopedic surgery and in dental implantology. In the current work, we studied the biological response of human osteoblasts with a bioactive glass. This bioactive glass is based on 50% Si0(2), 20% Na(2)O, 16% CaO, 6% P(2)O(5), 5% K(2)0, 2% Al(2)O(3) and 1% MgO and designated A9. Cracks and irregularities were observed on the material surface when it was immersed in the culture medium. In addition, energy dispersive X-ray analyses highlighted a selective release of the elements at the surface of the bioactive glass, such as Na(+) and K(+) ions, released from the first day, contrary to the Si, Al, Ca, P, and Mg elements, which were released more slowly. Cell proliferation kinetics, total protein synthesis, and DNA content of the osteoblasts in contact with bioactive glass were similar to control cells. The morphological studies by light and scanning electron microscopy revealed an increasing cellular density in culture with bioactive glass without contact inhibition. The immunohistochemical studies highlighted the expression of types I, III, and V collagens by osteoblasts cultured in the presence of bioactive glass. The pH measurement of the culture medium in the presence of bioactive glass demonstrated a slight alkalinization. We thus conclude that human osteoblasts preserve their properties in the presence of bioactive glass (A9).     

掺锶复合PVA/生物活性玻璃水凝胶的制备及其体外软骨修复性能研究

目的研究以聚乙烯醇(PVA)、生物活性玻璃(BG)及氯化锶为主要原料,制备的PVA水凝胶、PVA/生物活性玻璃水凝胶、掺锶复合PVA/生物活性玻璃水凝胶的可降解性能、离子释放性能和促软骨修复性能。方法PVA溶液与BG溶胶凝胶溶液在加热搅拌下生成PB水凝胶,PVA溶液与Sr-BG溶胶凝胶溶液加热搅拌生成PBSr水凝胶,将PB和PB-Sr水凝胶浸泡于磷酸盐缓冲液(PBS)中,研究其体外降解性能、离子释放性能和结构变化。在水凝胶上培养软骨细胞,经细胞增殖能力实验和细胞荧光染色观察细胞增殖情况。结果 PB和PB-Sr水凝胶在PBS溶液中逐渐降解,28 d后PB水凝胶降解率为25%,PB-Sr水凝胶降解率为16%,水凝胶表面均有羟基磷灰石形成。细胞实验结果显示培养7 d后PB-Sr水凝胶的OD值为0.76±0.04,PB水凝胶的OD值为0.52±0.02,均显著高于对照组,PVA水凝胶的OD值0.45±0.04,差异具有统计学意义(0.05)。结论该掺锶复合PVA/生物活性玻璃水凝胶具有良好的降解性能和离子释放性能,能有效促进软骨细胞增殖。     

In vitro and in vivo behavior of self-reinforced bioabsorbable polymer and self-reinforced bioabsorbable polymer/bioactive glass composites

The aim of this study was to investigate the in vitro and in vivo properties and degradation of (1) self-reinforced (SR) lactide copolymer, P(L/DL)LA 70:30, and (2) SR composites of the same polylactide and bioactive glass 13-93. The following three polymer and polymer-bioactive glass samples were studied: SR-PLA70, SR-PLA70 + BaG15s, and SR-PLA70 + BaG20c. In vitro behavior was studied in a phosphate-buffered saline for 87 weeks at 37 degrees +/- 1 degrees C and a pH of 7.4 +/- 0.2. In vivo behavior was studied by implanting the rods in the dorsal subcutaneous tissue of rats (SR-PLA70 + BaG20c) or rabbits (SR-PLA70 and SR-PLA70 + BaG15s) for 48 weeks. The degradation of the specimens was evaluated by measuring the changes in mechanical properties, crystallinity and molecular weight of polymer, water absorption, weight loss, and structural changes. Results showed that the addition of bioactive glass filler modified the degradation kinetics and material morphology.     

Time-dependent evaluation of mechanical properties and in vitro cytocompatibility of experimental composite-based nerve guidance conduits

The use of nerve guidance conduits to repair peripheral nerve discontinuities has attracted much attention from the biomaterials community, with many resorbable and non-resorbable materials in clinical use. However, a material with ideal biocompatibility, sufficient mechanical properties (to match that of the regenerating nerve) coupled with a suitable degradation rate, has yet to be realized. Recently, potential solutions (composite nerve guidance conduits) which support the emerging philosophy of allowing synthetic materials to establish key interactions with cells in ways that encourage self-repair (i.e. ionic mediators of repair such as those observed in hard tissue regeneration) have been proposed in the literature; such composites comprise specially designed bioactive phosphate-free glasses embedded in degradable polymeric matrices. Whilst much research has focussed on the optimization of such composites, there is no published literature on the performance of these experimental compositions under simulated physiological conditions. To address this key limitation, this paper explores the time-dependent variations in wet-state mechanical properties (tensile modulus and ultimate tensile strength) for NGC composites containing various compositions of PLGA (at 12.5, and 20 wt%), F127 (at 0, 2.5 and 5 wt%) and various loadings of Si–Na–Ca–Zn–Ce glass (at 0 and 20 wt%). It was observed that Young’s modulus and ultimate tensile strength of these composites were in the range 5–203 MPa and 1–7 MPa respectively, indicating comparable mechanical performance to clinical materials. Furthermore, an analysis of the cytocompatibility of experimental compositions showed comparable (in some instances superior), compatibility when compared with the commercial product Neurolac^®. Based on current synthetic devices and the demands of the indication, the CNGCs examined in this work offer appropriate mechanical properties and compatibility to warrant enhanced development.     

靶向EGFR 免疫毒素BI7D12-PE38KDEL 的制备及其体外活性测定

目的:构建基于EGFR 纳米抗体的免疫毒素BI7D12-PE38KDEL,并检测其对EGFR 肿瘤细胞的细胞毒作用。方法:采用分子克隆技术,将靶向EGFR 的纳米抗体7D12 以二价的形式,通过柔性连接肽(G4S)4 与铜绿假单胞菌外毒素的截断形式PE38KDEL 连接,构建原核表达载体pET28a-BI7D12-PE38KDEL。然后将其转化到BL21(DE3)感受态细胞,用IPTG进行诱导表达。通过镍柱亲和层析法纯化目的蛋白,并经Western blot 验证。通过流式细胞技术检测该免疫毒素与EGFR 阳性细胞A549、HT29、MCF-7 和EGFR 阴性细胞CEM、Jurkat 的结合能力后,将其按照一定的浓度梯度进行细胞毒实验研究,72 h后,使用WST-1 试剂检测BI7D12-PE38KDEL 对上述细胞的杀伤效果。结果:通过SDS-PAGE 和Western blot 实验验证,成功的制备了重组免疫毒素BI7D12-PE38KDEL,该毒素大部分以可溶性的方式表达。BI7D12-PE38KDEL 能够与EGFR 阳性的A549、HT29、MCF-7 肿瘤细胞特异性的结合,并且对上述细胞的细胞毒作用与阴性对照组CEM 和Jurkat 相比具有极其显著性差异(P<0.01)。结论:成功地构建了基于EGFR 纳米抗体的重组免疫毒素BI7D12-PE38KDEL,该免疫毒素能特异性的结合并杀伤EGFR 阳性的肿瘤细胞。