AIM; To evaluate the feasibility of electrochemical method combined with immunomagnetic sep-rnaration to specifically detect Porphyromonas gingivalis. METHODS: The impedance change of the bacterial suspen-sion before and after immunomagnetic separation was observed. The influence of magnetic particles, antibody concen-tration, immune time, temperature and pH on impedance measurement was also measured. RESULTS: Compared with the wilds, the impedance value of bacterial suspensions after immunomagnetic separation increased but not significant-ly. Magnetic particles and competing bacteria did not significantly interfere the impedance measurement. The normal-ized impedance change value reached maximum when the dilution concentration of antibody was 1 : 10. Thirty - minute immunoreaction time showed the most normalized impedance change, no more increase was found with longer times. Significant and relative steady impedance change was found when the temperature was between 25 ℃ and 37 ℃ , the impedance change decreased when the temperature was above 37 ℃. Obvious and relative steady impedance change was found when the pH was 7. 0 ~7. 5. CONCLUSION; Combined with immunomagnetic separation, the established electrochemical method based on impedance measurement could be used to specifically quantify aimed bacteria.%目的:探讨结合免疫磁分离技术实现电化学测菌法特异检测牙龈卟啉单胞菌的可行性.方法:利用结合特异抗体的磁颗粒捕获分离目的菌,观察免疫磁分离前、后检测样本的阻抗变化.分析磁颗粒、杂菌、抗体浓度、反应时间、温度、pH值对阻抗测量的影响.结果:与初始菌液相比,免疫磁分离后的阻抗值增加,但无统计学差异(P＞0.05)；磁颗粒和杂菌未对阻抗测量产生明显干扰；抗体浓度为1∶10稀释时系统阻抗变化最明显；抗原抗体结合30 min时系统阻抗变化最大,延长时间未见增加；温度在25～ 37℃范围内,系统阻抗变化较平稳,超过37℃时,系统阻抗值出现下降趋势；pH在7.0～7.5之间时,系统阻抗值较平稳.结论:免疫磁分离技术能够与电化学测菌法结合,实现细菌的特异检测.
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