Department of Chemical Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States.
J Am Chem Soc. 2014 Jan 15;136(2):713-24. doi: 10.1021/ja410433b. Epub 2014 Jan 3.
Temporal and spatial changes in neurotransmitter concentrations are central to information processing in neural networks. Therefore, biosensors for neurotransmitters are essential tools for neuroscience. In this work, we applied a new technique, corona phase molecular recognition (CoPhMoRe), to identify adsorbed polymer phases on fluorescent single-walled carbon nanotubes (SWCNTs) that allow for the selective detection of specific neurotransmitters, including dopamine. We functionalized and suspended SWCNTs with a library of different polymers (n = 30) containing phospholipids, nucleic acids, and amphiphilic polymers to study how neurotransmitters modulate the resulting band gap, near-infrared (nIR) fluorescence of the SWCNT. We identified several corona phases that enable the selective detection of neurotransmitters. Catecholamines such as dopamine increased the fluorescence of specific single-stranded DNA- and RNA-wrapped SWCNTs by 58-80% upon addition of 100 μM dopamine depending on the SWCNT chirality (n,m). In solution, the limit of detection was 11 nM [K(d) = 433 nM for (GT)15 DNA-wrapped SWCNTs]. Mechanistic studies revealed that this turn-on response is due to an increase in fluorescence quantum yield and not covalent modification of the SWCNT or scavenging of reactive oxygen species. When immobilized on a surface, the fluorescence intensity of a single DNA- or RNA-wrapped SWCNT is enhanced by a factor of up to 5.39 ± 1.44, whereby fluorescence signals are reversible. Our findings indicate that certain DNA/RNA coronae act as conformational switches on SWCNTs, which reversibly modulate the SWCNT fluorescence. These findings suggest that our polymer-SWCNT constructs can act as fluorescent neurotransmitter sensors in the tissue-compatible nIR optical window, which may find applications in neuroscience.
神经递质浓度的时空变化是神经网络信息处理的核心。因此，神经递质的生物传感器是神经科学的重要工具。在这项工作中，我们应用了一种新技术，即电晕相分子识别（CoPhMoRe），来识别吸附在荧光单壁碳纳米管（SWCNT）上的聚合物相，这些聚合物相允许对特定的神经递质进行选择性检测，包括多巴胺。我们用包含磷脂、核酸和两亲聚合物的不同聚合物（n = 30）对 SWCNT 进行功能化和悬浮，以研究神经递质如何调节所得带隙和 SWCNT 的近红外（nIR）荧光。我们确定了几个电晕相，这些电晕相允许对神经递质进行选择性检测。儿茶酚胺，如多巴胺，在添加 100 μM 多巴胺后，会使特定的单链 DNA 和 RNA 包裹的 SWCNT 的荧光增加 58-80%，具体取决于 SWCNT 的手性（n，m）。在溶液中，检测限为 11 nM [（GT）15 DNA 包裹的 SWCNT 的 Kd = 433 nM]。机制研究表明，这种开环响应是由于荧光量子产率的增加，而不是 SWCNT 的共价修饰或活性氧物质的清除。当固定在表面上时，单个 DNA 或 RNA 包裹的 SWCNT 的荧光强度增强了 5.39 ± 1.44 倍，其中荧光信号是可逆的。我们的研究结果表明，某些 DNA/RNA 电晕相在 SWCNT 上充当构象开关，可可逆地调节 SWCNT 的荧光。这些发现表明，我们的聚合物-SWCNT 构建体可以作为组织兼容的 nIR 光学窗口中的荧光神经递质传感器，这可能在神经科学中有应用。
