High sensitive mesoporous TiO₂-coated love wave device for heavy metal detection

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• 作者：I. Gammoudi^a ; ^b ; ^c ; ^{ibtisem.gammoudi@u-bordeaux1.fr" class="auth_mail} ; L. Blanc^a ; F. Moroté ; ^b ; C. Grauby-Heywang^b ; C. Boissiè ; re^d ; R. Kalfat^c ; D. Rebiè ; re^a ; T. Cohen-Bouhacina^b ; C. Dejous^a
• 关键词：TiO2 mesoporous ; Biosensor ; Heavy metals ; Escherichia coli ; Polyelectrolyte ; Love-waves ; AFM
• 刊名：Biosensors and Bioelectronics
• 出版年：15 July, 2014
• 年：2014
• 卷：57
• 期：Complete
• 页码：162-170
• 全文大小：7134 K

文摘

This work deals with the design of a highly sensitive whole cell-based biosensor for heavy metal detection in liquid medium. The biosensor is constituted of a Love wave sensor coated with a polyelectrolyte multilayer (PEM). Escherichia coli bacteria are used as bioreceptors as their viscoelastic properties are influenced by toxic heavy metals. The acoustic sensor is constituted of a quartz substrate with interdigitated transducers and a SiO₂ guiding layer. However, SiO₂ shows some degradation when used in a saline medium. Mesoporous TiO₂ presents good mechanical and chemical stability and offers a high active surface area. Then, the addition of a thin titania layer dip-coated onto the acoustic path of the sensor is proposed to overcome the silica degradation and to improve the mass effect sensitivity of the acoustic device.

PEM and bacteria deposition, and heavy metal influence, are real time monitored through the resonance frequency variations of the acoustic device. The first polyelectrolyte layer is inserted through the titania mesoporosity, favouring rigid link of the PEM on the sensor and improving the device sensitivity. Also, the mesoporosity of surface increases the specific surface area which can be occupied and favors the formation of homogeneous PEM. It was found a frequency shift near 鈭?0卤1 kHz for bacteria immobilization with titania film instead of 鈭?卤3 kHz with bare silica surface. The sensitivity is highlighted towards cadmium detection.

Moreover, in this paper, particular attention is given to the immobilization of bacteria and to biosensor lifetime. Atomic Force Microscopy characterizations of the biosurface have been done for several weeks. They showed significant morphological differences depending on the bacterial life time. We noticed that the lifetime of the biosensor is longer in the case of using a mesoporous TiO₂ layer.