羧甲基纤维素钠对大豆分离蛋白骨粘合性能的影响

Effects of Sodium Carboxymethyl Cellulose on Adhesion Properties of Soybean Protein Isolate onto Porcine Bones

【目的】以体外动物骨骼为试验对象,研究羧甲基纤维素钠(CMC-Na)对大豆分离蛋白(soybean protein isolate,SPI)胶粘合性能的影响,探讨其作为医用骨粘合剂的潜在可能。【方法】利用动态流变仪、圆二色光谱(CD)、ANS荧光探针法、扫描电镜等方法,分析CMC-Na对SPI胶零切黏度、二级结构(α-螺旋,β-折叠,β-转角和无规则卷曲)、疏水性、表面形态的影响,并结合以体外动物骨骼为试验对象,用万能材料试验机测定CMC-Na对SPI胶粘合强度的影响。【结果】SPI胶的粘合强度随着浓度的升高而增大,浓度大于10%时粘合强度呈下降趋势;微量CMC-Na(0.01%)的添加能显著提高低浓度SPI胶(2%)的粘合强度(是未添加时的2.4倍,P<0.01)。且粘合强度和零切黏度呈显著正相关关系(r=0.815,P=0.036);微量CMC-Na的添加能改变SPI胶的二级结构,其中β-折叠含量由42.2%上升至49.1%,β-转角由2.1%上升至7.3%,α-螺旋由28.0%下降至19.7%,无规则卷曲由27.7%下降至23.9%。CMC-Na的添加提高了SPI胶的疏水性,适度的疏水改性有助于增强粘合强度。扫描电镜图谱显示,CMC-Na的添加使SPI胶表面颗粒的排布更加规整和致密,更利于与骨骼粘合。【结论】CMC-Na的添加,导致SPI胶二级结构的改变。α-螺旋含量降低而β-折叠含量增加,表明蛋白质分子展开程度增加,内部疏水基团暴露,表面疏水性提高,增加了SPI胶零切黏度,从而显著提高低浓度SPI胶的骨粘合强度;而低浓度SPI胶更利于机体吸收。因此,添加CMC-Na的SPI胶更有潜力作为骨粘合剂应用于医疗领域。

【Objective】The effects of sodium carboxymethyl cellulose（CMC-Na） on the adhesion properties of soybean protein isolate（SPI） onto porcine bone were investigated by studying tensile bond strength, zero shear viscosity, secondary structure, hydrophobicity and scanning electronic microscopy（SEM） images. The aim of the research was to provide a basis for utilization of SPI adhesive in biomedical fields. 【Method】SPI adhesive prepared with/without CMC-Na was used to bond porcine bones in vitro and the effect of CMC-Na on tensile bond strength of SPI adhesive was measured using a tensile strength testing machine. The influence of CMC-Na on zero shear viscosity of the SPI adhesive was measured using a rheometer. The SPI adhesive with CMC-Na secondary structure was measured using circular dichroism spectra to determine the content of α-helix, β-sheet, β-turn and random coil. The influence of CMC-Na on hydrophobicity and surface morphology of SPI adhesive was measured using ANS（1-anilino-8-naphthalene sulfonate） fluorescent probe method and scanning electron microscopy（SEM）, respectively. 【Result】 The tensile bond strength of the SPI adhesive increased with the increase of its concentration and reached a peak at a SPI adhesive concentration of 10%, then began to decline. The adhesive strength of 2% SPI with addition of a trace amount of CMC-Na（at 0.01%） was increased 2.4 fold（P〈0.01） in comparison with the control. There was a significant positive correlation（r=0.815, P〈0.05） between adhesive strength and zero shear viscosity. The addition of trace CMC-Na influenced significantly the secondary structure of the SPI adhesive. The β-sheet and β-turn content increased from 42.2% to 49.1% and from 2.1% to 7.3%, respectively, while the α-helix and random coil content declined from 28.0% to 19.7% and from 27.7% to 23.9%, respectively. The hydrophobicity of the SPI adhesive with CMC-Na was increased significantly; even moderate hydrophobic modification of the SPI adhesive with CMC-Na benefited the increase of its adhesive strength. SEM showed that particles on the surface of the SPI adhesive with addition of CMC-Na arrayed more uniformly and compact than the control, which was beneficial for its adhering to the bones. 【Conclusion】The addition of a trace amount of CMC-Na caused significant changes in the secondary structure of the SPI adhesive, the decline in α-helix content and an increase in β-sheet content, all of which indicated the unfolding of protein molecules and the aggregation of unfolding protein molecules. The increase in the hydrophobicity and zero shear viscosity of the SPI adhesive resulted in the significant increase of bond strength of low concentration SPI adhesive onto porcine bone. Since low concentration SPI might be easier to be absorbed by bodies than at a high concentration, our results after the addition of CMC-Na suggest that SPI adhesive has a great potential to be utilized as an adhesive in medical fields.