Abstract
Delivery of biomolecules to target cells is an essential step in gene therapy, targeted drug delivery, and cell imaging, and can be achieved by encapsulation or conjugation to micro- or nanoparticles. For successful systemic delivery, these complexes must be stable under physiological conditions and prevent leakage of the cargo. Covalent binding of the active agent to a carrier is one-way to facilitate this stability but frequently requires several steps. Here we show that plasma immersion ion implantation (PIII) treatment can activate the surface of paramagnetic polystyrene microparticles (MPs), increasing autofluorescence and allowing conjugation of biological molecules in a single-step. Using PIII-activated MPs, we demonstrate covalent binding of therapeutically relevant payloads including antibodies (Abs) and small-interfering RNAs (siRNAs). The PIII-activated magnetic particles were actively taken up by the cells, were nontoxic, and could be visualized due to increased autofluorescence induced by the PIII treatment. Ab and siRNA were effectively conjugated simultaneously to the active surface, and these functionalized MPs were also taken up by cells. This simple PIII-based activation system has the potential to be applied to many different therapeutic approaches.