The beam of light carries momentum that can be used to pull or push a particle in a medium. By letting the light scattered from one dielectric medium into another with higher refractive-index, the linear momentum of photons, according to Minkowski theory, can be amplified appropriately. As a result, surface-bound objects can be pulled back to the light source within a specific range of the incident-angle. This paper demonstrates how the optical force can be used to filter foreign particles like bacteria or virus from a biological system which is based on the different optical nature of that foreign particles from the neighboring host ones. The proposed optical-filter works at gas-liquid interface and uses the incident-angle as the filtering parameter.