Impact of micron-sized diamond particles on barrier cells of the human small intestine

Abstract

Diamond and diamond-like materials have shown great potential in variety of biomedical applications, such as coatings for implantable materials, drug delivery systems or tools for bioimaging. Due to the outstanding features of diamond like low chemical reactivity and unique physical properties, as well as unprecedented biocompatibility, the future for development of that kind of material in terms of biomedicine is still very promising. Despite the general low toxicity of diamond, it is of huge importance to monitor effects resulting from different nano- and microforms of diamond showing distinct properties in comparison to their bulk counterpart. Systematic studies of biocompatibility and toxicity should always be strong requirements for understanding and mitigating potential health hazards. Also the size, shape, and surface chemistry should be thoroughly investigated as such particles' properties greatly affect particle internalization and stand for their ultimate toxicity towards cells. Here we aimed to assess the influence of micron-sized diamond particles on epithelial cells of the human small intestine (FHs 74 Int). These cells constitute the barrier between the gastrointestinal tract and internal environment of the human body, thus serving as one of the first routes of exposure to drugs or particles administered orally. We employed various microscopic methods to observe epithelial cells after exposure to microdiamond particles, evaluating cell movement, particle uptake, cell viability, apoptosis, and formation of micronuclei. We observed uptake and accumulation of microdiamond particles by cells during and after exposure in time-dependent manner. Microdiamond particles were neither cytotoxic nor genotoxic to epithelial cells, and the rate of apoptosis was not significantly different than that of untreated control cells, however it should be of high importance to monitor cell responses to diamond particles when used in specific biomedical applications. Our studies demonstrated that microdiamond particles even at very low concentration can be effectively accumulated inside cells and show no harmful effects on barrier intestinal cells. This renders them very promising candidate for drug delivery systems, competitive towards diamond particles of nano size that are in general more prone to evoke toxic effects due to their much smaller size. We strongly believe that the use of microdiamonds in biomedical field, especially as drug carriers is still undervalued, and should be developed with the same attention as is paid for diamonds of nano size.