Hatchell Christopher B, Jacobson David R
Department of Chemistry, Clemson University, Clemson, South Carolina 29634, USA.
Rev Sci Instrum. 2025 Jun 1;96(6). doi: 10.1063/5.0257032.
Atomic force microscopy (AFM)-based single-molecule force spectroscopy (SMFS) enables the characterization of individual biological molecules through the application of mechanical force. The spatiotemporal resolution of such measurements depends greatly on the AFM cantilever that is used, specifically its stiffness, hydrodynamic drag, and material composition. Prior work has shown that focused ion beam (FIB) lithographic modification of small cantilevers can be used to lower the spring constant (and thus force noise) and drift while maintaining a relatively fast time response. Published methods for implementing such optimization rely on specific FIB instruments and cantilever types, limiting broad implementation of these methods to improve SMFS data quality. Here, we show that it is possible to achieve such optimized properties using generalized techniques applicable to a broader array of FIB instruments and starting from new types of cantilevers that are presently commercially available. Modified cantilevers exhibited a 90% reduction in spring constant, sub-pN force drift to tens of seconds, and a time response of ∼25 μs in the liquid environment relevant to biological measurements.
基于原子力显微镜（AFM）的单分子力谱（SMFS）能够通过施加机械力来表征单个生物分子。此类测量的时空分辨率在很大程度上取决于所使用的AFM悬臂，具体而言取决于其刚度、流体动力学阻力和材料成分。先前的研究表明，对小型悬臂进行聚焦离子束（FIB）光刻修饰可用于降低弹簧常数（从而降低力噪声）和漂移，同时保持相对快速的时间响应。已发表的实现此类优化的方法依赖于特定的FIB仪器和悬臂类型，限制了这些方法的广泛应用以提高SMFS数据质量。在此，我们表明，使用适用于更广泛FIB仪器阵列的通用技术，并从目前市售的新型悬臂开始，可以实现此类优化特性。在与生物测量相关的液体环境中，修饰后的悬臂弹簧常数降低了90%，亚皮牛顿力漂移至数十秒，时间响应约为25微秒。
