Ullah Najeeb, Noureen Beenish, Tian Yulan, Du Liping, Chen Wei, Wu Chunsheng
Institute of Medical Engineering, Department of Biophysics, School of Basic Medical Science, Xi'an Jiaotong University Health Science Center, Xi'an 710061, China.
Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an 710061, China.
Nanomaterials (Basel). 2022 Apr 28;12(9):1505. doi: 10.3390/nano12091505.
Saxitoxin (STX) is a highly toxic and widely distributed paralytic shellfish toxin (PSP), posing a serious hazard to the environment and human health. Thus, it is highly required to develop new STX detection approaches that are convenient, desirable, and affordable. This study presented a label-free electrolyte-insulator-semiconductor (EIS) sensor covered with a layer-by-layer developed positively charged Poly (amidoamine) (PAMAM) dendrimer. An aptamer (Apt), which is sensitive to STX was electrostatically immobilized onto the PAMAM dendrimer layer. This results in an Apt that is preferably flat inside a Debye length, resulting in less charge-screening effect and a higher sensor signal. Capacitance-voltage and constant-capacitance measurements were utilized to monitor each step of a sensor surface variation, namely, the immobilization of PAMAM dendrimers, Apt, and STX. Additionally, the surface morphology of PAMAM dendrimer layers was studied by using atomic force microscopy and scanning electron microscopy. Fluorescence microscopy was utilized to confirm that Apt was successfully immobilized on a PAMAM dendrimer-modified EIS sensor. The results presented an aptasensor with a detection range of 0.5-100 nM for STX detection and a limit of detection was 0.09 nM. Additionally, the aptasensor demonstrated high selectivity and 9-day stability. The extraction of mussel tissue indicated that an aptasensor may be applied to the detection of STX in real samples. An aptasensor enables marine toxin detection in a rapid and label-free manner.
石房蛤毒素（STX）是一种毒性极强且分布广泛的麻痹性贝类毒素（PSP），对环境和人类健康构成严重危害。因此，迫切需要开发便捷、理想且经济实惠的新型STX检测方法。本研究提出了一种无标记的电解质-绝缘体-半导体（EIS）传感器，其表面覆盖有逐层制备的带正电荷的聚（酰胺胺）（PAMAM）树枝状大分子。一种对STX敏感的适配体（Apt）通过静电作用固定在PAMAM树枝状大分子层上。这使得Apt在德拜长度范围内呈优选的平面状态，从而减少电荷屏蔽效应并提高传感器信号。利用电容-电压和恒电容测量来监测传感器表面变化的每个步骤，即PAMAM树枝状大分子、Apt和STX的固定化。此外，通过原子力显微镜和扫描电子显微镜研究了PAMAM树枝状大分子层的表面形态。利用荧光显微镜确认Apt成功固定在PAMAM树枝状大分子修饰的EIS传感器上。结果表明，该适配体传感器对STX的检测范围为0.5-100 nM，检测限为0.09 nM。此外，该适配体传感器具有高选择性和9天的稳定性。贻贝组织提取物表明，适配体传感器可应用于实际样品中STX的检测。适配体传感器能够以快速且无标记的方式检测海洋毒素。
