Chemical and Biomolecular Engineering Department, University of California, Los Angeles, Los Angeles, CA 90095, USA.
Analyst. 2018 Oct 8;143(20):5008-5013. doi: 10.1039/c8an01343h.
High performance microprobes for combined sensing of glucose and choline were fabricated using microcontact printing (μCP) to transfer choline oxidase (ChOx) and glucose oxidase (GOx) onto targeted sites on microelectrode arrays (MEAs). Most electroenzymatic sensing sites on MEAs for neuroscience applications are created by manual enzyme deposition, which becomes problematic when the array feature size is less than or equal to ∼100 μm. The μCP process used here relies on use of soft lithography to create features on a polydimethylsiloxane (PDMS) microstamp that correspond to the dimensions and array locations of targeted, microscale sites on a MEA. Precise alignment of the stamp with the MEA is also required to transfer enzyme only onto the specified microelectrode(s). The dual sensor fabrication process began with polyphenylenediamine (PPD) electrodeposition on all Pt microelectrodes to block common interferents (e.g., ascorbic acid and dopamine) found in brain extracellular fluid. Next, a chitosan film was electrodeposited to serve as an adhesive layer. The two enzymes, ChOx and GOx, were transferred onto different microelectrodes of 2 × 2 arrays using two different PDMS stamps and a microscope for stamp alignment. Using constant potential amperometry, the combined sensing microprobe was confirmed to have high sensitivity for choline and glucose (286 and 117 μA mM cm-2, respectively) accompanied by low detection limits (1 and 3 μM, respectively) and rapid response times (≤2 s). This work demonstrates the use of μCP for facile creation of multianalyte sensing microprobes by targeted deposition of enzymes onto preselected sites of a microelectrode array.
采用微接触印刷（μCP）技术，将胆碱氧化酶（ChOx）和葡萄糖氧化酶（GOx）转移到微电极阵列（MEA）的目标位置，制备了用于葡萄糖和胆碱联合传感的高性能微探针。大多数用于神经科学应用的 MEA 上的电酶传感位点是通过手动酶沉积创建的，当阵列特征尺寸小于或等于约 100 μm 时，这会成为问题。这里使用的 μCP 工艺依赖于使用软光刻在 PDMS 微印章上创建与 MEA 上目标微尺度位点的尺寸和阵列位置相对应的特征。为了仅将酶转移到指定的微电极上，还需要精确对准印章和 MEA。双传感器制造工艺始于在所有 Pt 微电极上进行聚对苯二胺（PPD）电沉积，以阻止脑细胞外液中存在的常见干扰物（例如抗坏血酸和多巴胺）。接下来，电沉积壳聚糖膜作为粘附层。两种酶，ChOx 和 GOx，使用两个不同的 PDMS 印章和显微镜进行对准，分别转移到 2×2 阵列的不同微电极上。使用恒电位安培法，证实了组合传感微探针对胆碱和葡萄糖具有高灵敏度（分别为 286 和 117 μA mM cm-2），伴随低检测限（分别为 1 和 3 μM）和快速响应时间（≤2 s）。这项工作展示了使用 μCP 通过将酶靶向沉积到微电极阵列的预选位置来轻松创建多分析物传感微探针的用途。
