Confined Singlet Oxygen in Mesoporous Silica Nanoparticles: Selective Photochemical Oxidation of Small Molecules in Living Cells

Abstract

Chemical conversion of specific bioactive molecules by external stimuli in living cells is a powerful noninvasive tool for clarification of biomolecular interactions and to control cellular functions. However, in chaotic biological environments, it has been difficult to induce arbitrary photochemical reactions on specific molecules because of their poor molecular selectivity. Here we report a selective and nontoxic photochemical reaction system utilizing photoactivated mesoporous silica nanoparticles to control biological functions. Methylene blue modification within nanoparticle pores for photosensitization produced singlet oxygen confined to the pore that could mediate selective oxidation of small molecules without any damage to living cells. This intracellular photochemical system produced bioactive molecules in situ and remotely controlled the cell cycle phase. We also confirmed that this photoreaction could be applied to control cell cycle phase in tumor tissue transplanted in mice. The cell cycle phase in the cells in mice, to which our system was administered, was arrested at the G2/M phase upon photoirradiation. We demonstrate a simple and promising method for the exogenous conversion of an intracellular biomolecule to another functional compound.

Phosphonated mesoporous silica nanoparticles bearing ruthenium complexes used as molecular probes for tracking oxygen levels in cells and tissues

“…We recently demonstrated that 1 O 2 generated in these pores was rapidly deactivated and could not leak out from the pores. 27 More recently, we prepared MCM-41-type MSNs tethered to phosphorescent Ru complexes inside their pores (MSN-Rus) and used them to visualize oxygen uctuation in vitro and in vivo. 28 In the MSN-Rus, almost all of the ruthenium complexes were covalently attached in the silica mesopores, and therefore, their contact with intracellular biomolecules was limited, leading to negligible cytotoxicity.…”

Improving Continuous Flow Singlet Oxygen Photooxygenation Reactions with Functionalized Mesoporous Silica Nanoparticles

“…Moreover, the porous silica structure does not only act as a suitable carrier for hydrophobic molecules, but may also protect the loaded molecules from degradation. More specifically, the functionalization of MSNs with RB (RB@MSNs) was demonstrated to increase resistance toward photobleaching and to reduce the formation of deleterious ground‐state complexes,, and was successfully employed for photodynamic cancer therapy (PDT) ,,. Both the heterogenization of the PS and its protection against extensive photobleaching are interesting assets for continuous flow photooxygenations.…”

Metal- and Oxidant-Free Photoinduced Aromatic Trifluoromethylation Performed in Aerated Gel Media: Determining the Effects on Yield and Selectivity

“…This has inspired many research teams all over the world to fabricate numerous nano- and microreactors based on the self-assembly of low-molecular-weight (LMW) molecules via non-covalent interactions (e.g., hydrogen-bonding, π-π stacking, van der Waals, charge-transfer,) [1,2]. In particular, the field of photochemistry has been a big beneficiary of these materials [3,4], where key aspects that control photoinduced processes, such as light absorption and lifetime of redox intermediates, are improved in confined environments including, for example, mesoporous inorganic materials [5], microemulsions [6], micelles [7,8], vesicles [9], foams [10], polyelectrolyte nanoparticles [11], and gels [12,13,14]. Among these systems, supramolecular or physical gels are viscoelastic materials made of LMW compounds (i.e., gelators) that self-assembly into 3D networks through non-covalent interactions [15].…”