Department of Physics, Informatics and Mathematics, University of Modena and Reggio Emilia, 41125 Modena, Italy.
Center S3, CNR Institute Nanoscience, Via Campi 213/A, 41125 Modena, Italy.
Biomolecules. 2019 Jan 11;9(1):23. doi: 10.3390/biom9010023.
In the past three decades, the ability to optically manipulate biomolecules has spurred a new era of medical and biophysical research. Optical tweezers (OT) have enabled experimenters to trap, sort, and probe cells, as well as discern the structural dynamics of proteins and nucleic acids at single molecule level. The steady improvement in OT's resolving power has progressively pushed the envelope of their applications; there are, however, some inherent limitations that are prompting researchers to look for alternatives to the conventional techniques. To begin with, OT are restricted by their one-dimensional approach, which makes it difficult to conjure an exhaustive three-dimensional picture of biological systems. The high-intensity trapping laser can damage biological samples, a fact that restricts the feasibility of in vivo applications. Finally, direct manipulation of biological matter at nanometer scale remains a significant challenge for conventional OT. A significant amount of literature has been dedicated in the last 10 years to address the aforementioned shortcomings. Innovations in laser technology and advances in various other spheres of applied physics have been capitalized upon to evolve the next generation OT systems. In this review, we elucidate a few of these developments, with particular focus on their biological applications. The manipulation of nanoscopic objects has been achieved by means of plasmonic optical tweezers (POT), which utilize localized surface plasmons to generate optical traps with enhanced trapping potential, and photonic crystal optical tweezers (PhC OT), which attain the same goal by employing different photonic crystal geometries. Femtosecond optical tweezers (fs OT), constructed by replacing the continuous wave (cw) laser source with a femtosecond laser, promise to greatly reduce the damage to living samples. Finally, one way to transcend the one-dimensional nature of the data gained by OT is to couple them to the other large family of single molecule tools, i.e., fluorescence-based imaging techniques. We discuss the distinct advantages of the aforementioned techniques as well as the alternative experimental perspective they provide in comparison to conventional OT.
在过去的三十年中，光学操纵生物分子的能力开创了医学和生物物理研究的新时代。光镊（OT）使实验者能够捕获、分类和探测细胞，并在单分子水平上辨别蛋白质和核酸的结构动力学。OT 分辨率的稳步提高逐渐推动了其应用范围的扩大；然而，一些固有的局限性促使研究人员寻找传统技术的替代品。首先，OT 受到其一维方法的限制，这使得难以全面了解生物系统的三维图像。高强度捕获激光会损坏生物样本，这一事实限制了体内应用的可行性。最后，在纳米尺度上直接操纵生物物质仍然是传统 OT 的一个重大挑战。在过去的 10 年中，大量文献致力于解决上述缺点。激光技术的创新和应用物理学各个领域的进步被利用来发展下一代 OT 系统。在这篇综述中，我们阐述了其中的一些进展，特别关注它们的生物学应用。通过等离子体光镊（POT）实现了对纳米物体的操纵，POT 利用局域表面等离激元产生具有增强捕获潜力的光阱，通过采用不同的光子晶体几何形状的光子晶体光镊（PhC OT）实现了相同的目标。飞秒光镊（fs OT）通过用飞秒激光取代连续波（cw）激光源来构建，有望大大减少对活样本的损伤。最后，超越 OT 获得的一维数据的一种方法是将其与另一个大型单分子工具家族相结合，即荧光成像技术。我们讨论了上述技术的独特优势，以及它们相对于传统 OT 提供的替代实验视角。
