Mesoporous silica-based nanoplatforms for the delivery of photodynamic therapy agents

Abstract

Photodynamic therapy (PDT) is an established method for the treatment of cancer which utilizes light, a photosensitizer (PS), and oxygen. Unfavourable characteristics of most PSs, such as low solubility and tumour specificity have led many researchers to adopt nanoscale drug delivery platforms for use in PDT. Mesoporous silica nanoparticles (MSNs) form a significant part of that effort, due to their ease and controllability of synthesis, ease of loading, availability of diverse surface functionalization, and biocompatibility. Therefore, in this review, we discuss the properties of MSNs as they pertain to their use in PDT and review the latest advances in the field, comparing the different approaches currently being used.

Keywords: Biocompatibility; Controlled release; Drug delivery; Mesoporous silica; Nanocarrier; Photodynamic therapy; Theranostic platform.

Fig. 1

A general schematic drawing of a multifunctional PDT platform. All platforms have a mSiO₂ base and a loaded PS. Optional features are indicated with blue text. Sometimes, a single component will serve multiple functions. (Color figure online)

Fig. 2

A representation of the design of PPIX-loaded MSN with FITC, lipid and folate, and the experiments conducted. Reprinted with permission from Teng et al. (2013) with permission from Elsevier

Fig. 3

Physical appearances of UCN@mSiO₂ under ambient lighting and 980 nm laser excitation a before and after dual loading with ZnPc and MC540, and b after loading with one of the PSs. The PSs absorb their respective wavelength ranges, as denoted in c, and luminescence that is not absorbed due to lack of PS in that wavelength range is observed in the picture. Reprinted by permission from Macmillan Publishers Ltd: Gnanasammandhan et al. (2016)

Fig. 4

A schematic drawing of the ‘off–on’ property of talaporfin-loaded HMSN. TS stands for talaporfin sodium. When particles are internalized by cancer cells, photosensitizer is released and becomes highly fluorescent and phototoxic. Reprinted with permission from Hong et al. (2017a)

Fig. 5

Procedure of synthesis for dSiO₂@mSiO₂ with HP-conjugated mesopores. Reprinted with permission from Zhang et al. (2009). Copyright 2009 American Chemical Society

Fig. 6

Synthesis process of UCN@dSiO₂(-MB)@mSiO₂ loaded with Rhodamine B and capped. Chemical mechanism for the singlet oxygen-responsive linker. Reprinted with permission from Wang et al. (2016). Copyright 2016 American Chemical Society