Nanoparticle applications in biotechnology and biomedicine are steadily increasing. In biological fluids, proteins bind to nanoparticles that form the protein corona, crucially affecting the nanoparticles' biological identity. As the corona affects in vitro and/or in vivo nanoparticle applications, we developed a method to obtain time-resolved protein corona profiles formed on various nanoparticles. After incubation in plasma or a similar biofluid, or after injection into a mouse, the first analytical step is sedimentation of the nanoparticle-protein complexes through a sucrose cushion, thereby allowing analysis of early corona formation time points. Next, corona profiles are visualized by gel electrophoresis and quantitatively analyzed after tryptic digestion using label-free liquid chromatography-high-resolution mass spectrometry. In contrast to other approaches, our established methodology allows the researcher to obtain qualitative and quantitative high-resolution corona signatures. The protocol can be readily extended to the investigation of protein coronas from various nanomaterials (as an example, we applied this protocol to different silica nanoparticles (SiNPs) and polystyrene nanoparticles (PSNPs)). Depending on the number of samples, the protocol from nanoparticle-protein complex recovery to data evaluation takes ~8-12 d to complete.

Proteolysis is not only a critical requirement for life, but the executing enzymes also play important roles in numerous pathological conditions, including cancer. Therefore, targeting proteases is clearly relevant for improving cancer patient care. However, to effectively control proteases, a profound knowledge of their mechanistic function as well as their regulation and downstream signalling in health and disease is required. The highly conserved protease Threonine Aspartase1 (Taspase1) is overexpressed in numerous liquid and solid malignancies and was characterized as a 'non-oncogene addiction' protease. Although Taspase1 was shown to cleave various regulatory proteins in humans as well as leukaemia provoking mixed lineage leukaemia fusions, our knowledge on its detailed functions and the underlying mechanisms contributing to cancer is still incomplete. Despite superficial similarity to type 2 asparaginases as well as Ntn proteases, such as the proteasome, Taspase1-related research so far gives us the picture of a unique protease exhibiting special features. Moreover, neither effective genetic nor chemical inhibitors for this enzyme are available so far, thus hampering not only to further dissect Taspase1's pathobiological functions but also precluding the assessment of its clinical impact. Based on recent insights, we here critically review the current knowledge of Taspase1's structure-function relationship and its mechanistic relevance for tumorigenesis obtained from in vitro and in vivo cancer models. We provide a comprehensive overview of tumour entities for which Taspase1 might be of predictive and therapeutic value, and present the respective experimental evidence. To stimulate progress in the field, a comprehensive overview of Taspase1 targeting approaches is presented, including coverage of Taspase1-related patents. We conclude by discussing future inhibition strategies and relevant challenges, which need to be resolved by the field.

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Circulating tumor cells (CTCs) are disseminated cancer cells. The occurrence and circulation of CTCs seem key for metastasis, still the major cause of cancer-associated deaths. As such, CTCs are investigated as predictive biomarkers. However, due to their rarity and heterogeneous biology, CTCs’ practical use has not made it into the clinical routine. Clearly, methods for the effective isolation and reliable detection of CTCs are urgently needed. With the development of nanotechnology, various nanosystems for CTC isolation and enrichment and CTC-targeted cancer therapy have been designed. Here, we summarize the relationship between CTCs and tumor metastasis, and describe CTCs’ unique properties hampering their effective enrichment. We comment on nanotechnology-based systems for CTC isolation and recent achievements in microfluidics and lab-on-a-chip technologies. We discuss recent advances in CTC-targeted cancer therapy exploiting the unique properties of nanomaterials. We conclude by introducing developments in CTC-directed nanosystems and other advanced technologies currently in (pre)clinical research.

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