Mesoporous silicon oxycarbide (SiOC) components were formed with the use of "molecular spacer" (a sacrificial vinyl-terminated linear siloxane which while decomposing during pyrolysis generates pores with size proportional to the molecular weight), followed by a post-pyrolysis etching treatment by hydrofluoric acid (HF) to obtain C-rich SiOC samples having additional micro-/mesoporosity and specific surface area reaching to 774 m(2)/g. The biocompatibility of the samples was validated by hemolysis test, and their cargo/drug loading capacities were studied by two different sized polypeptides as model molecules. SiOC particles showed less hemolysis compared to the reference material MCM-41. Similarly, the loading capacity and the release kinetics of bovine serum albumin (BSA) and vancomycin-loaded SiOC particles were improved compared to that of MCM-41. In the multi cargo loading/release capacity tests, done by using different size molecules, Bio2-HF and MCM-41 were loaded both with fluorescein and BSA. While a lagging time in fluorescein release was observed for MCM-41, the release kinetics of fluorescein and BSA was not affected when they are loaded together in the hierarchical pores of Bio2-HF, allowing the release of both large and small cargo molecules. The antimicrobial activity tests showed that Bio2-HF performed better than MCM-41 particles in improving bactericidal activity. (C) 2017 Elsevier Ltd. All rights reserved.