  Controllable continuous release of functional materials from capsules is one
of the unmet functions of theragnosis particles; on this way, understanding
cargo-fluid interactions in vitro is an essential milestone. We develop a
flexible platform to investigate single particle-fluid interactions utilizing a
glass micropipette as a highly localized flow source around an optically
trapped particle. In proof-of-concept experiments this microparticle is
sensitive to local microflows distribution, thus serving as a probe. The very
same flows are capable of the particle rotating (i.e., vaterite drug cargo) at
frequencies dependent on the mutual particle-pipette position. The platform
flexibility comes from different interactions of a tweezer (optical forces) and
a pipette (mechanical/hydrodynamical) with micro-particle, which makes this
arrangement an ideal micro-tool. We studied the vaterite dissolution kinetics
and demonstrated it can be controlled on demand, providing a wide cargo release
dynamic rate. Our results promote using inorganic mesoporous nanoparticles as a
nanomedicine platform.
