The Design of Anionic Surfactant-Based Amino-Functionalized Mesoporous Silica Nanoparticles and their Application in Transdermal Drug Delivery

Abstract

Melanoma remains the most lethal form of skin cancer and most challenging to treat despite advances in the oncology field. Our work describes the utilization of nanotechnology to target melanoma locally in an attempt to provide an advanced and efficient quality of therapy. Amino-functionalized mesoporous silica nanoparticles (MSN-NH₂) were developed in situ through the utilization of anionic surfactant and different volumes of 3-aminopropyltriethoxysilane (APTES) as a co-structure directing agent (CSDA). Prepared particles were characterized for their morphology, particles size, 5-flurouracol (5-FU) and dexamethasone (DEX) loading capacity and release, skin penetration, and cytotoxicity in vitro in HT-144 melanoma cells. Results of transmission electron microscopy (TEM) and nitrogen adsorption-desorption isotherm showed that using different volumes of APTES during the functionalization process had an impact on the internal and external morphology of the particles, as well as particle size. However, changing the volume of APTES did not affect the diameter of formed mesochannels, which was about 4 nm. MSN-NH₂ showed a relatively high loading capacity of 5-FU (12.6 ± 5.5) and DEX (44.72 ± 4.21) when using drug: MSN-NH₂ ratios of 5:1 for both drugs. The release profile showed that around 83% of 5-FU and 21% of DEX were released over 48 h in pH 7.4. The skin permeability study revealed that enhancement ratio of 5-Fu and DEX using MSN-NH₂ were 4.67 and 5.68, respectively, relative to their free drugs counterparts. In addition, the accumulation of drugs in skin layers where melanoma cells usually reside were enhanced approximately 10 times with 5-FU and 5 times with DEX when delivering drugs using MSN-NH₂ compared to control. MSN-NH₂ alone was nontoxic to melanoma cells when incubated for 48 h in the range of 0 to 468 µg/mL. The combination of 5-FU MSN-NH₂ and DEX MSN-NH₂ showed significant increase in toxicity compared to their free dug counterparts and exhibited a synergetic effect as well as the ability to circumvent DEX induced 5-FU resistance in melanoma cells.

Keywords: 5-flurouracil; amino functionalized; dexamethasone; melanoma; mesoporous silica nanoparticles; transdermal.

Figure 1

TEM images of MSN-NH₂ prepared with different volumes of 3-aminopropyltriethoxysilane (APTES): (A) 50 μL, (B) 75 μL, (C) 100 μL, and (D) 150 μL. Scale bar = 100 nm.

Figure 2

(A) N₂ sorption isotherm and (B) pore size distribution of MSN-NH₂ prepared with different volumes of APTES: (a) 50 μL, (b) 75 μL, (c) 100 μL, and (d) 150 μL.

Figure 3

FTIR spectra of MSN-NH₂ prepared with different volumes of APTES: (a) 50 μL, (b) 75 μL, (c) 100 μL, and (d) 150 μL.

Figure 4

TEM images of MSN-NH₂ after drug loading. DEX MSN-NH₂ (A), 5-FU MSN-NH₂ (B), and combined MSN-NH₂; mixed DEX MSN-NH₂ and 5-FU MSN-NH₂ (1:1 ratio) (C). bar = 500 nm.

Figure 5

Particle size of free and drug loaded MSN-NH₂ measured by DLS in distilled water as a function of time.

Figure 6

(A) FT-IR spectra of (a) 5-FU, (b) MSN-NH₂, and (c) 5-FU MSN-NH_2. (B) FT-IR spectra of (a) DEX, (b) MSN-NH₂, and (c) DEX MSN-NH_2.

Figure 7

(A) DSC Thermograms of (a) 5-FU, (b) MSN-NH₂, and (c) 5-FU MSN-NH₂. (B) DSC thermograms of (a) DEX, (b) MSN-NH₂, and (c) DEX MSN-NH_2.

Figure 8

Release profiles of 5-FU and DEX in PBS (pH 7.8) from MSN-NH_2, free in gel, and control (A). Relaxational to diffusional ratio as a function of time for DEX and 5-FU from MSN-NH2 at pH of 7.4 (B). The Fickian release fraction of DEX/5-FU MSN-NH₂ gel (C). Permeability of 5-FU and DEX in MSN-NH₂ and free in gel (D). Data are represented as mean ± SD (n = 3).

Figure 9

5-FU (A) and DEX (B) accumulation in different skin layers and receptor media when delivered by MSN-NH2 and free in gel. Data are represented as mean ± SD (n = 3). Statistical significance was obtained with p-values ≤ 0.05, where * p ≤ 0.05, ** p ≤ 0.01, *** p ≤ 0.001.

Figure 10

MSN-NH₂-loaded 5-FU or DEX impairs the viability of HT-144 cells. Cytotoxicity of drug free MSN-NH₂, 5-FU + DEX free, and 5-FU MSN-NH₂ + DEX MSN-NH₂ in HT-144 cells incubated for (A) 24 h and (B) 48 h. A comparison of the cytotoxicity between 5-FU MSN-NH₂ alone, DEX MSN-NH₂ alone, and 5-FU MSN-NH₂ + DEX MSN-NH₂ in HT-144 after incubation for (C) 24 h and (D) 48 h. Data are represented as mean ± SD (n = 3). Statistical significance was obtained with p-values ≤ 0.05, where * p ≤ 0.05, ** p ≤ 0.01, *** p ≤ 0.001, and **** p < 0.0001.