Center for Bio/Molecular Science and Engineering, U.S. Naval Research Laboratory Code 6900, Washington, D.C. 20375, United States.
Fischell Department of Bioengineering, University of Maryland, College Park, Maryland 20742, United States.
ACS Appl Mater Interfaces. 2022 Jan 19;14(2):3404-3417. doi: 10.1021/acsami.1c19411. Epub 2022 Jan 4.
There is significant interest in developing photothermal systems that can precisely control the structure and function of biomolecules through local temperature modulation. One specific application is the denaturation of double-stranded (ds) DNA through femtosecond (fs) laser pulse optical heating of gold nanoparticles (AuNPs); however, the mechanism of DNA melting in these systems is not fully understood. Here, we utilize 55 nm AuNPs with surface-tethered dsDNA, which are locally heated using fs laser pulses to induce DNA melting. By varying the dsDNA distance from the AuNP surface and the laser pulse energy fluence, this system is used to study how the nanosecond duration temperature increase and the steep temperature gradient around the AuNP affect dsDNA dehybridization. Through modifying the distance between the dsDNA and AuNP surface by 3.8 nm in total and the pulse energy fluence from 7.1 to 14.1 J/m, the dehybridization rates ranged from 0.002 to 0.05 DNA per pulse, and the total amount of DNA released into solution was controlled over a range of 26-93% in only 100 s of irradiation. By shifting the dsDNA position as little as ∼1.1 nm, the average dsDNA dehybridization rate is altered up to 30 ± 2%, providing a high level of control over DNA melting and release. By comparing the theoretical temperature around the dsDNA to the experimentally derived temperature, we find that maximum or peak temperatures have a greater influence on the dehybridization rate when the dsDNA is closer to the AuNP surface and when lower laser pulse fluences are used. Furthermore, molecular dynamics simulations mimicking the photothermal heat pulse around a AuNP provide mechanistic insight into the stochastic nature of dehybridization and demonstrate increased base pair separation near the AuNP surface during laser pulse heating when compared to steady-state heating. Understanding how biological materials respond to the short-lived and non-uniform temperature increases innate to fs laser pulse optical heating of AuNPs is critical to improving the functionality and precision of this technique so that it may be implemented into more complex biological systems.
人们对于开发光热系统有着浓厚的兴趣，这些系统可以通过局部温度调节精确控制生物分子的结构和功能。一个特定的应用是通过飞秒（fs）激光脉冲光加热金纳米粒子（AuNPs）使双链（ds）DNA 变性；然而，这些系统中 DNA 熔化的机制尚未完全理解。在这里，我们利用表面连接有 dsDNA 的 55nm AuNPs，通过 fs 激光脉冲局部加热来诱导 DNA 熔化。通过改变 dsDNA 与 AuNP 表面的距离和激光脉冲能量密度，我们使用这个系统来研究纳秒持续时间的温度升高和 AuNP 周围的陡峭温度梯度如何影响 dsDNA 解链。通过总共改变 dsDNA 与 AuNP 表面的距离 3.8nm 和脉冲能量密度从 7.1 到 14.1J/m，解链速率从每个脉冲 0.002 到 0.05DNA 不等，并且在 100s 的辐照时间内将释放到溶液中的 DNA 总量控制在 26-93%的范围内。通过将 dsDNA 位置移动小至约 1.1nm，平均 dsDNA 解链速率变化高达 30±2%，对 DNA 熔化和释放具有高度的控制能力。通过将理论上的 dsDNA 周围温度与实验得出的温度进行比较，我们发现当 dsDNA 更接近 AuNP 表面和使用较低的激光脉冲密度时，最大或峰值温度对解链速率的影响更大。此外，模拟 AuNP 周围光热热脉冲的分子动力学模拟为解链的随机性提供了机制上的见解，并表明与稳态加热相比，在激光脉冲加热期间 AuNP 表面附近的碱基对分离增加。了解生物材料如何响应固有于 fs 激光脉冲光加热 AuNPs 的短暂和不均匀的温度升高，对于提高该技术的功能和精度至关重要，以便将其应用于更复杂的生物系统。
