In this paper, autonomous 2-D manipulation and pattern formation of microparticles under an optical microscope by pushing and pulling them with a sharp nanoprobe is presented. For calibration of the camera and to achieve a larger bandwidth on position control, an iterative sliding mode parameter observer is designed that satisfies the Lyapunov stability criterion. A procedure that allows particles to stick near the tip of the nanoprobe while pushing/pulling and to release them when placed to the target position is used for manipulation. For pattern formation, a trajectory planning algorithm based on a metric that defines the blockage of trajectories by particles and target positions is used to order manipulation of particles such that the particle that blocks the most number of trajectories is pulled/pushed to the target position that blocks the least number of trajectories. This ordering of manipulation performs better than the conventional distance-based approaches due to the fact that it minimizes the number of blockages to the linear trajectories. Efficiency of the approach is demonstrated on simulation and experimental results by positioning 4.5-mum diameter polystyrene particles on a flat glass substrate autonomously. The average accuracy of the pushing/pulling operations is less than 0.64 mum.