Amino acid as a biodegradation accelerator of mesoporous silica nanoparticles

Abstract

© 2019 Elsevier Inc. In order to avoid cumulative toxicity of the remained mesoporous silica nanoparticles (MSNs) in biological systems, three amino acids (aâs), i.e., glycine (Gly), aspartic acid (Asp) and cysteine (Cys), were incorporated into MSNs for accelerating their biodegradation. Aâ was conjugated with 3-isocyanatopropyl triethoxysilane (ICPTES) before reacting with tetraethyl orthosilicate to form aâ-MSNs via the sol-gel process based co-condensation. FTIR spectra confirmed the urea bond formation in aâ-ICPTES, whereas silicon resonances of T2 and T3 in 29Si NMR spectrum indicated the incorporation of aâ in MSNs. Spherical bare-MSNs (112 nm) were obtained while the rod-like particles were formed in the case of Gly-MSNs (73 nm in length), Asp-MSNs (90 nm in length), and Cys-MSNs (163 nm in length). The trend of %Si dissolution rate analyzed from microwave plasma-atomic emission spectrometer (MP-AES) of aâ-MSNs in phosphate buffer saline (PBS)/trypsin enzyme (pH 7.4) was 3–5 times higher than in PBS (pH 7.4) and 7–8 times higher than in acetate buffer (pH 5.2), respectively. The Asp-MSNs having two carboxylic groups showed the highest degradability, followed by Cys-MSNs, Gly-MSNs, and bare-MSNs in all three media. By capability of aâ as a dissolution promoter, the aâ-MSNs would be an effective and alternative material used as drug carrier in biomedical applications.