Diatoms decorated with gold nanoparticles by In-situ and Ex-situ methods for in vitro gentamicin release

The use of natural diatoms is currently a topic of interest for therapeutic applications due to its facilities, low cost, and biocompatibility. Here, we report the chemical modification of diatoms Aulacoseria genus microalgae-derived biosilica from Guayllabamba - Ecuador decorated with gold nanoparticles by In-situ and Ex-situ methods to study the in vitro gentamicin loading and release properties in simulated body fluid (SBF). Successful decoration of the diatoms and loaded with gentamicin was confirmed using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Raman spectroscopy and Fluorescence Microscopy. We follow the In-vitro drug release by using Ultraviolet-Visible Spectroscopy (UV-vis). Our results revealed that diatoms decorated with gold nanoparticles using the Ex-situ method (Au/CTAB-Diatom) showed a faster release reaching a maximum of 93% in 10 days and a lower loading rate, while the samples decorated by the In-situ method presented longer and slower release behavior. Fluorescence properties were enhanced after the gentamicin loaded. The advantage of this work is the control of the structural and optical properties of diatoms decorated with gold nanoparticles for the gentamicin drug delivery.