Drug carrier systems based on mesoporous inorganic nanoparticles generally face the problem of fast clearance from bloodstream thus failing in passive and active targeting to cancer tissue. To address this problem, a specific dual PEGylation (DPEG) method for mesoporous silicon (PSi) was developed and studied in vitro and in vivo. The DPEG coating changed significantly the behavior of the nanoparticles in vivo, increasing the circulation half-life from 1 to 241 min. Furthermore, accumulation of the coated particles was mainly taking place in the spleen whereas uncoated nanoparticles were rapidly deposited in the liver. The protein coronas of the particles differed considerably from each other. The uncoated particles had substantially more proteins adsorbed including liver and immune active proteins, whereas the coated particles had proteins capable of suppressing cellular uptake. These reasons along with agglomeration observed in blood circulation were concluded to cause the differences in the behavior in vivo. The biofate of the particles was monitored with magnetic resonance imaging by incorporating superparamagnetic iron oxide nanocrystals inside the pores of the particles making dynamic imaging of the particles feasible. The results of the present study pave the way for further development of the porous inorganic delivery system in the sense of active targeting as the carriers can be easily chemically modified allowing also magnetically targeted delivery and diagnostics.

The practical use of quantum dots (QD) as diagnostic, visualizing and therapeutic nano-agents depends on the understanding of fundamental mechanisms of their entrance and trafficking within cells. Here we show that CdSe/ZnS carboxylic-coated QD (COOH-QD) enter fibroblast cells via lipid raft/caveolin-mediated endocytosis, pass early sorting endosomes and accumulate in the multivesicular bodies, but not in the lysosomes. Later phase of their endocytosis leads to the generation of lipid raft/caveolin-dependent endocytosis inhibition that prevents intracellular uptake of new COOH-QD, but not the QD coupled with platelet-derived growth factor BB (PDGF-QD). PDGF-QD enter fibroblasts by the clathrin-mediated endocytosis and undergo similar intracellular trafficking as COOH-QD, yet they accumulate in lysosomes in contrast to COOH-QD. The PDGF-QD activate PDGF receptor-beta and are mitogenic, however, COOH-QD suppress cell migration and chemotaxis. Data show that surface coating of QD with the biologically active proteins redirects their intracellular traffic routes and changes their biological activity.

Fluorophores with multifunctional properties known as rare-earth-doped nanoparticles (RENPs) are promising candidates for bioimaging, therapy, and drug delivery. When applied in vivo , these nanoparticles (NPs) have to retain long blood-circulation time, bypass elimination by phagocytic cells, and successfully arrive at the target area. Usually, NPs in a biological medium are exposed to proteins, which form the so-called “protein corona” (PC) around the NPs and influence their targeted delivery and accumulation in cells and tissues. Different surface coatings change the PC size and composition, subsequently deciding the fate of the NPs. Thus, detailed studies on the PC are of utmost importance to determine the most suitable NP surface modification for biomedical use. When it comes to RENPs, these studies are particularly scarce. Here, we investigate the PC composition and its impact on the cellular uptake of citrate-, SiO 2 -, and phospholipid micelle-coated RENPs (LiYF 4 :Yb 3+ ,Tm 3+ ). We observed that the PC of citrate- and phospholipid-coated RENPs is relatively stable and similar in the adsorbed protein composition, while the PC of SiO 2 -coated RENPs is larger and highly dynamic. Moreover, biocompatibility, accumulation, and cytotoxicity of various RENPs in cancer cells have been evaluated. On the basis of the cellular imaging, supported by the inhibition studies, it was revealed that RENPs are internalized by endocytosis and that specific endocytic routes are PC composition dependent. Overall, these results are essential to fill the gaps in the fundamental understanding of the nano-biointeractions of RENPs, pertinent for their envisioned application in biomedicine.

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Potential drug target identification and mechanism of action is an important step in drug discovery process, which can be achieved by biochemical methods, genetic interactions or computational conjectures. Sometimes more than one approach is implemented to mine out the potential drug target and characterize the on-target or off-target effects. A novel anticancer agent RH1 is designed as pro-drug to be activated by NQO1, an enzyme overexpressed in many types of tumors. However, increasing data show that RH1 can affect cells in NQO1-independent fashion. Here, we implemented the bioinformatics approach of modeling and molecular docking for search of RH1 targets among protein kinase species. We have examined 129 protein kinases in total where 96 protein kinases are in complexes with their inhibitor, 11 kinases were in the unbound state with any ligand and for 22 protein kinases 3D structure were modeled. Comparison of calculated free energy of binding of RH1 with indigenous kinase inhibitors binding efficiency as well as alignment of their pharmacophoric maps let us predict and ranked protein kinases such as KIT, CDK2, CDK6, MAPK1, NEK2 and others as the most prominent off-targets of RH1. Our finding opens new avenues in search of protein targets that might be responsible for curing cancer by new promising drug RH1 in NQO1-independent way.