Ong Wee-Liat, Tang Kum-Cheong, Agarwal Ajay, Nagarajan Ranganathan, Luo Lian-Wee, Yobas Levent
Institute of Microelectronics, 11 Science Park Road, Science Park II, Singapore, 117685.
Lab Chip. 2007 Oct;7(10):1357-66. doi: 10.1039/b707439e. Epub 2007 Jul 17.
High-throughput screening of drug candidates for channelopathies can greatly benefit from an automated patch-clamping assay. Automation of the patch clamping through microfluidics ideally requires on-chip integration of glass capillaries with substantially round cross section. Such round capillaries, if they can only be integrated to connect isolated reservoirs on a substrate surface, will lead to a "lateral" configuration which is simple yet powerful for the patch clamping. We demonstrate here "lateral" patch clamping through microfluidic integration of substantially round glass capillaries in a novel process. The process adopts two well-known phenomena from microelectronics: keyhole-void formation and thermal-reflow of phosphosilicate glass in silicon trenches. The process relies on the same physical principle as the preparation of conventional micropipette electrodes by heat-pulling and fire-polishing glass tubes. The optimized process forms capillaries with a diameter approximately 1.5 microm and variation <10%. Functionality of the integrated glass capillaries for the patch-clamp recording has been verified by statistical test results from a sample of one hundred capillaries on mammalian cells (RBL-1) in suspension: 61% formed gigaseals (>1 GOmega) and of those approximately 48% (29% of all) achieved whole-cell recordings. Pharmacological blockade of ion channel activity and longevity of a whole-cell mode on these capillaries have also been presented.
针对通道病候选药物的高通量筛选能够从自动膜片钳检测中极大受益。通过微流控实现膜片钳自动化，理想情况下需要在芯片上集成具有大致圆形横截面的玻璃毛细管。这种圆形毛细管，如果仅用于连接衬底表面上的孤立储液器，将形成一种“横向”结构，这种结构对于膜片钳来说简单却强大。我们在此展示了一种通过在新工艺中对大致圆形玻璃毛细管进行微流控集成来实现“横向”膜片钳的方法。该工艺采用了微电子学中的两种著名现象：硅沟槽中磷硅玻璃的锁孔空洞形成和热回流。该工艺依赖于与通过热拉和火抛光玻璃管制备传统微吸管电极相同的物理原理。优化后的工艺形成的毛细管直径约为1.5微米，变化<10%。通过对悬浮状态下的哺乳动物细胞（RBL-1）上的一百个毛细管样本进行统计测试结果，验证了集成玻璃毛细管用于膜片钳记录的功能：61%形成了千兆欧封接（>1 GΩ），其中约48%（占总数的29%）实现了全细胞记录。还展示了这些毛细管上离子通道活性的药理学阻断以及全细胞模式的寿命。
