PROJECT SUMMARY The capability to precisely control behaviors of biomolecules in living cells is a challenging task. Current methods can be classified into chemical-based and laser-based approaches. For example, small molecule inhibitors or activators can be introduced into the biological system for manipulating enzyme activities. However, it is impossible to control the interaction locations with high precision, which poses off-target effects. Protein control using genetic methods such as gene silencing or editing might selectively impact a targeted protein, but requires transfection and incubation, and cannot be performed in real-time. Optical techniques such as optical tweezers can manipulate small targets at the laser focus, but can only interact with a few targets at a time. Current laser manipulation and ablation methods usually require a pre-acquired image together with a manual selection of target locations on samples. This method is not only time-consuming but also unsuitable to apply to highly dynamic living biological samples. Optogenetic methods can control neuron functions using light radiation and light-sensitive ion channels, but only at the single-cell level. There’s no existing technology that can select molecular targets in cells and control only these targets at sub-micron resolution in real-time. In this application, we develop a real-time precision opto-control (RPOC) platform that can selectively and precisely control biomolecules only at the desired interaction site using lasers. RPOC is based on a high-speed laser scanning system. First, during the laser scanning, an optical signal is generated at a specific pixel from the target molecule. Then, this optical signal will be compared with a preset threshold and to send out an electronic signal to control an acousto-optic modulator which is used as a fast switch to couple another laser beam to interact with the same pixel. The optical signal detection, processing, and laser control happen within 20 ns, much faster than the pixel dwell time. Digital logic circuits will also be designed with the comparator circuits to control the interaction laser beam based on the logic output from multiple signal channels. We will use photo- switchable proteins and design photo-convertible inhibitors and activators to demonstrate precision control of enzyme activities on site. Furthermore, we will use multiple continuous-wave lasers and acousto-optic tunable filters to design a portable and multicolor RPOC that can operate outside an optical lab. RPOC can accurately control and manipulate biomolecules in real-time without affecting other biomolecules in the system. It is highly chemical selective since the optical signal can be selected from fluorescence, Raman, or absorption signals. It will allow biologists to control and interrogate only the biomolecules of interest during laser scanning without affecting other parts of the sample with sub-micron precision. RPOC would be widely applied to ...