單分子拴球實驗為一簡單量測蛋白質與DNA 作用情形的單分子技術。利用高解析的光學顯微技術，我們得以準確地觀測接連在DNA 及玻片表面的乳膠小球之布朗運動情形，並藉由其布朗運動的大小直接對應到在生化反應中DNA 長度的變化，因此單分子拴球實驗已被廣泛地應用於研究單一蛋白質與單一DNA 分子作用之反應機制。我們更利用在乳膠小球上施加一微小伸展力來抑制其布朗運動大小，並藉此改良出施力式拴球實驗。此施力設計不僅改善實驗之解析度，擴展可應用之DNA 長度範圍，並得到一理論可預測之DNA 長度與布朗運動的線性關係。此施力式拴球實驗已被用來研究RecBCD 解螺旋與DNA 分子作用情形，發現此解螺旋分子沿DNA 移動時，藉由辨識DNA 特殊序列來調控其性質，並表現出移動速率由快轉慢之改變。

Tethered particle motion (TPM) method is a simple technique to study the protein-DNA interactions at the single molecule level. By directly imaging the Brownian motion of the polystyrene bead， which is tethered to the coverslip through a DNA molecule， TPM allows the real-time measurement of DNA length change during enzymatic processes. We developed a force TPM experiment to further improve the resolution of the measurement， to extend the DNA application range and to achieve a linear and predictable relation between DNA length and bead Brownian motion. This FTPM method has been used to study the motion of a DNA helicase， RecBCD， along individual duplex DNA molecules and provided insights on its protein-DNA interaction.