Mesoporous Silica Nanomaterials: Versatile Nanocarriers for Cancer Theranostics and Drug and Gene Delivery

Abstract

Mesoporous silica nanomaterials (MSNs) have made remarkable achievements and are being thought of by researchers as materials that can be used to effect great change in cancer therapies, gene delivery, and drug delivery because of their optically transparent properties, flexible size, functional surface, low toxicity profile, and very good drug loading competence. Mesoporous silica nanoparticles (MSNPs) show a very high loading capacity for therapeutic agents. It is well known that cancer is one of the most severe known medical conditions, characterized by cells that grow and spread rapidly. Thus, curtailing cancer is one of the greatest current challenges for scientists. Nanotechnology is an evolving field of study, encompassing medicine, engineering, and science, and it has evolved over the years with respect to cancer therapy. This review outlines the applications of mesoporous nanomaterials in the field of cancer theranostics, as well as drug and gene delivery. MSNs employed as therapeutic agents, as well as their importance and future prospects in the ensuing generation of cancer theranostics and drug and therapeutic gene delivery, are discussed herein. Thus, the use of mesoporous silica nanomaterials can be seen as using one stone to kill three birds.

Keywords: cancer theranostics; cancer therapy; drug delivery; gene therapy; mesoporous silica nanomaterials; stem cell.

Figure 1

Silica nanoparticles used as contrast agents for ultrasound and magnetic resonance imaging. (A) SEM images of porous hollow silica nano- and microshells having different particle size: (a) 100 nm, (b) 500 nm, and (c) 2000 nm. (Reproduced from Reference [32] with the permission of Elsevier Ltd.) (B) Ultrasound imaging of gas-filled silica microshells present in tumor-bearing mice; (a) intraperitoneal IGROV-1 ovarian tumor in the dissected nu/nu mouse, (b) Cadence contrast pulse sequencing (CPS) image, and (c) B-mode image of the particles through the tumor cross-section one (1) hour post injection with silica nanoparticles, (d) overlay of CPS image and B-mode image (red arrow = tumor, green arrow = spinal column, blue arrow = bottom of the mouse). (C) In vivo accumulation of silica nanoparticles at tumor site; (a) structural diagram of functionalized silica nanoparticles, (b) in vivo MRI of functionalized silica nanoparticles in tumor-bearing mice. Liver and tumor sites are indicated as L and T, respectively. Reproduced from Reference [33] with the permission of Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Figure 2

Production and assembly of mesoporous silica-based chips for proteomic uses. (A) Chemical changes taking place in the solution during the production phases of a mesoporous silica film; (a) fresh solution, (b) Micelles formation, (c) spin-coating process leading to self-assembly, (d) magnified image of a pore post-aging at high temperature. (B) SEM and TEM cross-sectional images of GX6 chip on a (a) bulk silicon wafer surface (upper) and (b) mesoporous silica film-coated silicon wafer surface (lower). Scale bar is 500 nm. Reproduced from Reference [34] with the permission of Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Figure 3

Synthesis of the tri-functionalized mesoporous silica nanomaterial (MSN), A647@MSN-RGD-PdTPP. The nanomaterials were initially functionalized with ATTO 647N, then photodynamic therapy photosensitizer (PS) agent (APTMS-PdTPP), and lastly with the tumor targeting ligand (cRGD). Reproduced from Reference [58] with permission from The Royal Society of Chemistry.

Figure 4

Tri-functionalized mesoporous nanomaterials employed as theranostic compounds that possess distinctive domains for localized photodynamic therapy photosensitizers, traceable imaging, as well as capable targeted delivery. Reproduced from Reference [58] with permission from The Royal Society of Chemistry.

Figure 5

(A) MSNs possess impedance disparity to backscatter ultrasound, MRI signal via Gd³⁺, and an optical signal from fluorescein. The same nanoparticles increase MSC survival by ensuring insulin-like growth factor (IGF) sustained release. (B) TEM images illustrate mesoporous particles with 4.1 nm pores (C) determined by line profiling (D). The red box present in (B) shows the area imaged at a higher magnification in (C). The line in C is representative of the profile used to create (D). (E) DLS data of the MSNs. Additional characterization by EDS shows projected peaks for silicon and oxygen along with gadolinium from the secondary tag (F). The copper signal in (F) is from the TEM grid. Panel (G) is a histogram of MSN sizes from the TEM data in nanometer (nm). Reproduced from Reference [91] with permission from the theranostics ivyspring international publisher.

Figure 6

Delivery of genes (MSN-mediated). (A,B) Confocal microscopy of Arabidopsis root cells treated with DNA–MSN complexes (1:100 ratio) for 48 h at 24 °C in 1/2 MS. Gene expression (mCherry protein; red) was observed in endodermal (A) and cortical (B) cells. TMAPS/F-MSNs were present in cells expressing mCherry (B, green channel). Scale bars: 50 mm. (C,D) TEM of immunogold-labelled mCherry protein in root cells after incubation with DNA–MSN complexes. Red arrows show the gold-labeled mCherry proteins. Presence of TMAPS/F-MSNs (black arrow) and mCherry protein (red arrows) in the same cell (D). Scale bars are 200 nm. Cp, cytoplasm; M, mitochondrion; V, vacuole; G, Golgi apparatus. Reproduced from Reference [120] with permission from The Royal Society of Chemistry.

Figure 7

(a) Schematic representation of targeted drug delivery to the lower part of the gastrointestinal (GI) tract. Reproduced from Reference [145] with permission from Elsevier Ltd.; (b) delivery system with anti-inflammatory azo-prodrug (sulfasalazine). Reproduced from Reference [146] with permission from John Wiley & Sons, Inc.; (c) pH-sensitive nanocarrier obtained from MSNs modified with ß-lactoglobulin. Reproduced from Reference [147] with permission from John Wiley & Sons, Inc.