<p>The interaction of silica nanoparticles with catalase and human mesenchymal stem cells: biophysical, theoretical and cellular studies</p>

Abstract

Aim Nanoparticles (NPs) have been receiving potential interests in protein delivery and cell therapy. As a matter of fact, NPs may be used as great candidates in promoting cell therapy by catalase (CAT) delivery into high oxidative stress tissues. However, for using NPs like SiO 2 as carriers, the interaction of NPs with proteins and mesenchymal stem cells (MSCs) should be explored in advance. Methods In the present study, the interaction of SiO 2 NPs with CAT and human MSCs (hMSCs) was explored by various spectroscopic methods (fluorescence, circular dichroism (CD), UV-visible), molecular docking and dynamics studies, and cellular (MTT, cellular morphology, cellular uptake, lactate dehydrogenase, ROS, caspase-3, flow cytometry) assays. Results Fluorescence study displayed that both dynamic and static quenching mechanisms and hydrophobic interactions are involved in the spontaneous interaction of SiO 2 NPs with CAT. CD spectra indicated that native structure of CAT remains stable after interaction with SiO 2 NPs. UV-visible study also revealed that the kinetic parameters of CAT such as Km, Vmax, Kcat , and enzyme efficiency were not changed after the addition of SiO 2 NPs. Molecular docking and dynamics studies showed that Si and SiO 2 clusters interact with hydrophobic residues of CAT and SiO 2 cluster causes minor changes in the CAT structure at a total simulation time of 200 ps. Cellular assays depicted that SiO 2 NPs induce significant cell mortality, change in cellular morphology, cellular internalization, ROS elevation, and apoptosis in hMSCs at higher concentration than 100 µg/mL (170 µM). Conclusion The current results suggest that low concentrations of SiO 2 NPs induce no substantial change or mortality against CAT and hMSCs, and potentially useful carriers in CAT delivery to hMSC.

Developing electropositive citric acid–polyethylenimine carbon quantum dots with high biocompatibility and labeling performance for mesenchymal stem cells in vitro and in vivo

“…10,11 So far, some QDs containing metal ions have been used to image MSCs, in which their surfaces are usually modified with biocompatible molecules. [13][14][15][16] For example, CdTe/ZnS QDs modified with a short chain polypeptide and cyclodextrin have been used to image MSCs and acquire good imaging signals in vitro and in vivo. 12 CdTe/ZnS QDs modified with polyethylene glycol not only shows good imaging results for MSCs, but also exhibits less cell toxicity than naked CdTe/ZnS QDs, 13 due to the polyethylene glycol on the surface of the CdTe/ ZnS QDs being more biocompatible than the CdTe/ZnS QDs.…”

Exploring In Vivo Pulmonary and Splenic Toxicity Profiles of Silicon Quantum Dots in Mice

“…The significant decrease in the specific activity of CAT at 6 h post injection ( Figure 4 d) confirmed a possible direct interaction between hydrophobic residues of CAT and SiQDs, generating a change in the α-helix structure of protein as it was previously proven [ 49 ], with consequences of the decrease in enzymatic activity. However, after 24 h, the CAT activity returned to values close to those of the control, suggesting the dynamic tertiary structure of CAT, that could be re-arranged in time, restoring the enzymatic activity [ 50 ]. Similar results regarding splenic CAT activity after the administration of CdSe QDs were also reported by Das et al [ 48 ].…”

Nanoparticle protein corona: from structure and function to therapeutic targeting

“…NP-protein interactions differ depending on the type of NP, composition, and distinct physiochemical properties such as size, curvature, shape, and surface charge. 33,34 The intrinsic stability of a protein determined by its secondary structure also impacts its interaction with NPs and the extent to which a protein undergoes conformational changes on the surface of NPs. 28,29,35 Interestingly, NP-induced conformational changes in proteins are a double-edged sword.…”

“…180 However, although hydrophobic forces primarily govern the interactions between SiO 2 NPs and catalase, the enzyme still retains its native structure and activity. 33 The interaction of SiO 2 NPs with human tau protein, whose intracellular neurofibrillary tangles are involved in Alzheimer's disease, changes the intrinsically unfolded structure of tau to partially folded structures and amorphous aggregates, which is accompanied by an increase in its α-helix and β-sheet contents and a loss of its random coil structures. 181,182 Intrinsically disordered proteins (IDPs), such as α-casein, Sic1, and α-synuclein, preserve their structural disorder when adsorbed onto SiO 2 NPs, forming a hard PC.…”

“…180 However, although hydrophobic forces primarily govern the interactions between SiO 2 NPs and catalase, the enzyme still retains its native structure and activity. 33…”