Laser-Cooling-Driven Opto-Thermophoretic Tweezers

光镊因其在生物系统中的应用而获得2018年诺贝尔物理学奖。镊子使用高度聚焦的激光束捕获和操纵小物体，包括细胞，颗粒，细菌和病毒。尽管光镊取得了巨大的成功，但对复杂光学设置和高工作功率的要求阻止了它们对易碎物体的非侵入性操作。人们已经做出了巨大的努力来开发新的光学捕获技术。然而，在各种液体环境中安全操纵不同颗粒和细胞的通用策略仍然难以捉摸。该方案旨在开发一种基于激光冷却和温度梯度中颗粒热迁移的新型光镊平台。激光冷却可以在基板上产生局部冷点，其中各种颗粒可以通过热泳被捕获。冷却诱导捕获有望有效避免传统光镊中由于光加热而导致的热损伤，并且一般的热泳迁移行为允许该策略用于广泛的生物细胞和纳米颗粒，以推进生命科学和生物医学应用，包括组织工程，细胞生物学，早期疾病诊断和药物递送。在物理学，光子学，热流体学，胶体科学和生物学的接口拟议的研究将为研究生，本科生和K-12学生提供跨学科的研究机会。外展工作将被整合到两个现有的妇女在工程计划倡议在校园内，以增加招聘妇女和代表性不足的少数民族进入工程。光热泳镊是近年来发展起来的一种在光控制的温度梯度中操纵粒子和细胞的替代策略，具有简单的光学和低操作功率。然而，现有的基于激光加热的光热泳镊子在特殊溶剂条件下的适用性有限，并且存在潜在的光热损伤。本计画的目的是发展及应用新型的光热泳光镊。由于胶体物种中常见的热恐惧症，各种生物细胞和颗粒可以通过热泳被捕获在激光束中。此外，这种设计可以避免由于光镊和基于加热的光热泳镊的温度升高而引起的热损伤。这项研究将为纳米粒子和生物细胞的多功能和非侵入性光学操作提供一个新的平台。其智力价值在于，拟议的研究将提高对激光冷却和热泳的基本理解，建立生物介质中细胞的安全光学操纵技术，并推进光镊的生物应用，包括细胞研究，该奖项反映了NSF的法定使命，并被认为是值得通过使用基金会的知识价值和更广泛的影响审查标准。

Optical tweezers won the 2018 Nobel Prize in physics for their applications in biological systems. The tweezers use a highly focused laser beam to trap and manipulate small objects, including cells, particles, bacteria, and virus. Despite the huge success of optical tweezers, the requirement of sophisticated optical setups and high working power prevent their non-invasive manipulation of fragile objects. Tremendous efforts have been made to develop new techniques for optical trapping. However, a universal strategy to safely manipulate different particles and cells in various liquid environments is still elusive. This proposal aims to develop a new optical tweezing platform based on laser cooling and thermal migration of particles in a temperature gradient. Laser cooling can create a localized cold spot on a substrate where various particles can be trapped by thermophoresis. The cooling-induced trapping is expected to effectively avoid the thermal damages due to optical heating in conventional optical tweezer, and the general thermophoretic migration behavior allows this strategy to be used for a wide range of biological cells and nanoparticles to advance life sciences and biomedical applications, including tissue engineering, cellular biology, early disease diagnosis, and drug delivery. The proposed research at the interfaces of physics, photonics, thermo-fluidics, colloidal sciences, and biology will provide interdisciplinary research opportunities for graduate students, undergraduate students, and K-12 students. The outreach efforts will be integrated into two existing Women in Engineering Program initiatives on campus to increase recruiting women and underrepresented minorities into engineering. Opto-thermophoretic tweezers were recently developed as an alternative strategy to manipulate particles and cells in a light-controlled temperature gradient with simple optics and low operation power. However, the current laser-heating-based opto-thermophoretic tweezers suffer from limited applicability to special solvent conditions and potential optothermal damages. The objective of this proposal is to develop and apply new opto-thermophoretic tweezers based on laser cooling of the substrates. Due to the common thermophobia in colloidal species, a variety of biological cells and particles can be trapped at the laser beams via thermophoresis in their native environments. In addition, this design can avoid thermal damages due to the temperature increase in optical tweezers and the heating-based opto-thermophoretic tweezers. The proposed research will provide a novel platform for versatile and non-invasive optical manipulation for nanoparticles and biological cells. The intellectual merit is that the proposed research will improve fundamental understanding of laser cooling and thermophoresis, establish safe optical manipulation techniques for cells in biological media, and advance biological applications of optical tweezers, including studies of cell-cell interactions and thermal cues in cellular behaviors.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.