Luminescent silicon-based nanocarrier for drug delivery in colorectal cancer cells

Abstract

Nanocarriers sensitive to exogenous or endogenous stimuli emerged as an attractive alternative to target drug delivery, with inorganic silica mesoporous nanoparticles (MNs) playing a core role in the development of a new generation of non-toxic and tuneable nanocarriers. A sensitive nanovector (NANO1) comprising luminescent silicon quantum dots (SiQDs) and functionalized with MNs was synthesised and loaded with doxorubicin (DOX). NANO1 nanoparticles have a size of 74 ± 10 nm and DOX loading percentages of ca. 43%. As a control sample, a similar nanocarrier (NANO2), without SiQDs, was also synthesised and loaded with DOX. Release profile studies, in PBS, revealed the strong NANO1@DOX pH-dependant behaviour, with a pH 5.0 favouring the release of DOX to percentages of ca. 70%. Cytotoxicity assessments of both free and DOX-loaded nanocarriers were evaluated in human cell lines of colon, revealing both free drug and drug-loaded nanoparticles to be concentration-dependent.

Magneto-Fluorescent Mesoporous Nanocarriers for the Dual-Delivery of Ofloxacin and Doxorubicin to Tackle Opportunistic Bacterial Infections in Colorectal Cancer

“…and ca. 3.0 % wt., respectively), which was in accordance with the already reported tendency for aminated DOX-containing delivery nanocarriers [ 34 , 42 ], as is the case of all NANO3 systems. Here, there was a compromise between DOX solubility at different pHs and the surface steric hinderance created by the aminated SiQD, with acidic pHs not only increasing DOX solubility in aqueous media, but also the protonation of surface NH 2 groups and the creation an electrostatic repulsion between surface SiQDs.…”

“…Beyond their physiochemical properties, and as NANO3 synthesis sought to produce hybrid magneto-fluorescent materials, the assessment of their spectral properties (i.e., fluorescence and magnetism) was also of utter importance. As-synthesized aqueous SiQDs, as previously reported [ 42 ], due to their incorporation of N and O atoms, have a typical green emission, with a maximum emission band centered at 530 nm ( Figure 3 a). The anchoring of SiQDs on the surface of NANO2-COOH rendered the final NANO3 with a similar, although slightly blue shifted, bluish-green, emission, with an emission maximum centered at 515 nm ( Figure 3 b).…”

“…Due to their small size and similar nature to the silica mesoporous layer, no SiQDs could be directly distinguished, being only perceived as the loss of the smooth surface of the particles in detriment of an embossed surface with blob-like structures of ca. 3.6 nm ( Figure 2 g) [ 42 ]. Elemental analysis on NANO3 was assessed via dark-field STEM analysis, that confirmed Si, O, N and Fe as the main constituents ( Figure S5 ), with iron atoms being confined to the core of the particles and the remaining elements to the outer silica layer.…”

“…In an adaption of the synthesis detailed by Marcelo et al [ 42 ], green emissive silicon quantum dots (SiQDs) were prepared by dissolving 50 mg of sodium ascorbate in 10 mL miliQ H 2 O and mixing with 2 mL of APTES. The reaction was initially stirred for 40 min at 50 °C and aged for 24 h at room temperature.…”

“…In an attempt to improve the system, and prepare it for further application against cancer and related bacterial infections, in this work we report on the synthesis of a magneto-fluorescent mesoporous nanosystem for the combinatory delivery of doxorubicin and ofloxacin, as model anticancer drug and antibiotic. With the produced nanosystem, comprised of a superparamagnetic iron oxide core, a mesoporous silica matrix and fluorescent silicon quantum dots (SiQDs), we seek to bring together the hyperthermia properties of the magnetic core [ 22 , 26 ], the cargo capacity of the mesoporous silica and the trackable fluorescence of SiQDs [ 42 ], while using sustainable, biocompatible, and biodegradable materials. The antimicrobial activity is tested against a set of common bacterial strains, usually associated with cancer, to validate their application in a combined therapy.…”