Enhanced photodynamic selectivity of nano-silica-attached porphyrins against breast cancer cells

Abstract

The synthesis and characterization of bare silica (4 nm in diameter) nanoparticle-attached meso-tetra(N-methyl-4-pyridyl)porphine (SiO2-TMPyP, 6 nm in diameter) are described for pH-controllable photosensitization. Distinguished from organosilanes, SiO2 nanoparticles were functionalized as a potential quencher of triplet TMPyP and/or singlet oxygen (1O2) at alkaline pH, thereby turning off sensitizer photoactivity. In weak acidic solutions, TMPyP was released from SiO2 surface for efficient production of 1O2. By monitoring 1O2 luminescence at 1270 nm, quantum yields of 1O2 production were found to be pH-dependent, dropping from ~ 0.45 in a pH range of 3–6 to 0.08 at pH 8–9, which is consistent with pH-dependent adsorption behavior of TMPyP on SiO2 surface. These features make bare SiO2-attached cationic porphyrin a promising candidate for use in PDT for cancer treatment in which efficient 1O2 production at acidic pH and sensitizer deactivation at physiological pH are desirable. The enhanced therapeutic selectivity was confirmed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) tests and trypan blue exclusion tests of cell viability in breast cancer cell lines. Bimolecular quenching rate constants of 1O2 by free TMPyP, SiO2 and SiO2-TMPyP nanoparticles were also determined.

Solvatochromic Stokes shift and determination of excited state dipole moments of free base and zinc octaethylporphyrin

“…A plethora of porphyrin derivatives have been extensively studied due to their fascinating photophysical and electrochemical properties [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. Intrinsically, porphyrins are biogenic molecules responsible for various biological processes such as photosynthesis and respiration [19][20][21][22][23][24][25][26][27][28][29].…”

“…Intrinsically, porphyrins are biogenic molecules responsible for various biological processes such as photosynthesis and respiration [19][20][21][22][23][24][25][26][27][28][29]. Porphyrins have wide applications in solar energy harvesting and artificial photosynthesis [7][8][9][12][13][14][15][16][30][31][32], industrial processes as catalysts [1][2][3][4]6,[33][34][35], photodynamic therapy [11,17,36], anticancer pharmaceutical drugs [10] and photodynamic destruction of viruses [5,37]. Therefore, knowledge on the solvent dependent photophysical properties of porphyrin molecules is extremely important for designing molecular devices of medical, bio-medical and environmental importance.…”

Multimodal use of the porphyrin TMPyP: From cancer therapy to antimicrobial applications

“…Li et al reported the synthesis of silica nanoparticles with TMPyP attached [86]. Their results indicated that while in an alkaline pH environment the silica particles quench the TMPyP 1 O 2 production, in weak acidic solutions (characteristic of tumor environments) TMPyP is released and ROS production is recovered.…”

Functionalized nanomaterials: their use as contrast agents in bioimaging: mono- and multimodal approaches

“…One material that may prove useful in combining a dual imaging and therapy is mesoporous silica NPs; with their large surface areas and pore volumes, one or two modalities (optical imaging agent and an anticancer drug) can be incorporated into the silica matrix while loading the other modality into its pores. [509][510][511] Encapsulating drug payloads in NPs can prevent exposure of healthy cells to the cytotoxic drug and may prove more beneficial (e.g., lower toxicity and fewer side effects) at lower doses than the free drug. However, this can reveal much more complex than the use of simple small-molecule drugs that are easily characterized.…”