Controlling the Interaction of Nanodiamond Surfaces with Physiologic Environments

The application of nanodiamond in quantum sensing, tissue engineering or drug delivery requires a highly defined interaction of the diamond surface with the surrounding medium. The uncontrolled formation of a protein corona is one of the major challenges. Furthermore, the denaturing of surface bound functional moieties as well as the attachment of serum components can lead e.g. to a loss of function, masking of functional moieties, the uncontrolled agglomeration of the particles as well as alteration in the uptake mechanism for the introduction of diamond nanoparticles into cells.[1] We have recently reported on the use of a complex zwitterionic moiety for the inhibition of the protein corona formation and the efficient uptake of such functionalized fluorescent nanodiamonds into cells.[2,3]<br/>Here, we discuss the control of these undesired effect by the highly defined modification of the diamond surface using different zwitterionic moieties based on differently charged small peptides as well as crown ethers immobilized using short organic linker molecules.<br/>The resulting nanodiamond conjugates have been investigated regarding their dispersibility, colloidal stability and inhibition of protein adsorption.<br/>Uptake experiments and cell based assays confirm the low toxicity and high biocompatibility of these functionalized nanodiamonds and elucidate the efficient uptake and release into the cytosol without substantial agglomeration. The influence of differently charged surface moieties will be discussed. Such functionalized nanodiamonds are a promising tool for biomedical and sensing applications as the modular approach allows to introduce additional functional moieties, which can then be used to deliver drug molecules, provide specific interactions for targeting and tissue engineering.<br/><br/>[1] E. Mayerhoefer, A. Krueger, <i>Acc. Chem. Res.</i> <b>2022</b>,<i> 55</i>, 3594.<br/>[2] V. Merz, J. Lenhart, Y. Vonhausen, M. E. Ortiz Soto, J. Seibel, A. Krueger, <i>Small</i> <b>2019</b>, 1901551.<br/>[3] A. Sigaeva, Viktor Merz, R. Sharmin, R. Schirhagl, Anke Krueger, <i>J. Mater. </i><i>Chem. C</i> <b>2023</b>, <i>11</i>, 6642.