Institute of Biomedical Chemistry, Pogodinskaya Str. 10/8, 119121 Moscow, Russia.
A.V. Shubnikov Institute of Crystallography of Federal Scientific Research Centre "Crystallography and Photonics" of Russian Academy of Sciences, Leninsky Ave. 59, 119333 Moscow, Russia.
Biomolecules. 2023 Dec 12;13(12):1776. doi: 10.3390/biom13121776.
Currently, there is great interest in the development of highly sensitive bioanalytical systems for diagnosing diseases at an early stage, when pathological biomarkers are present in biological fluids at low concentrations and there are no clinical manifestations. A promising direction is the use of molecular detectors-highly sensitive devices that detect signals from single biomacromolecules. A typical detector in this class is the atomic force microscope (AFM). The high sensitivity of an AFM-based bioanalysis system is determined by the size of the sensing element of an atomic force microscope-the cantilever-the radius of the curvature of which is comparable to that of a biomolecule. Biospecific molecular probe-target interactions are used to ensure detection system specificity. Antibodies, aptamers, synthetic antibodies, and peptides can be used as molecular probes. This study has demonstrated the possibility of using aptamers as molecular probes for AFM-based detection of the ovarian cancer biomarker CA125. Antigen detection in a nanomolar solution was carried out using AFM chips with immobilized aptamers, commercially available or synthesized based on sequences from open sources. Both aptamer types can be used for antigen detection, but the availability of sequence information enables additional modeling of the aptamer structure with allowance for modifications necessary for immobilization of the aptamer on an AFM chip surface. Information on the structure and oligomeric composition of aptamers in the solution was acquired by combining small-angle X-ray scattering and molecular modeling. Modeling enabled pre-selection, before the experimental stage, of aptamers for use as surface-immobilized molecular probes.
目前，人们对开发高度敏感的生物分析系统以在早期诊断疾病非常感兴趣，此时病理生物标志物以低浓度存在于生物流体中，并且没有临床表现。一个有前途的方向是使用分子探测器——高度敏感的设备，这些设备可以检测来自单个生物大分子的信号。在这一类中，典型的探测器是原子力显微镜（AFM）。基于原子力显微镜的生物分析系统的高灵敏度取决于原子力显微镜的传感元件-悬臂梁的尺寸，其曲率半径与生物分子的曲率半径相当。生物特异性分子探针-靶相互作用用于确保检测系统的特异性。抗体、适体、合成抗体和肽可以用作分子探针。本研究证明了使用适体作为分子探针，通过基于原子力显微镜的 CA125 卵巢癌生物标志物检测的可能性。使用固定在 AFM 芯片上的适体（商业上可获得的或基于开放源序列合成的）在纳摩尔溶液中进行了抗原检测。两种适体类型都可用于抗原检测，但序列信息的可用性允许对适体结构进行额外的建模，考虑到将适体固定在 AFM 芯片表面上所需的修饰。通过结合小角 X 射线散射和分子建模获得了溶液中适体的结构和寡聚组成信息。建模能够在实验阶段之前预选适体作为表面固定的分子探针。
