Nanoemulsion drug delivery by ketene based polyester synthesized using electron rich carbon/silica composite surface

A new carrier matrix for nanoemulsion drug delivery was synthesized from glycine as the raw material, using mesoporous/microporous electron rich carbon–silica composite surface (MAC800). MAC800 was prepared from rice husk in two-stage carbonization. The surface area, pore volume, and pore size distribution of MAC800 were measured, using nitrogen adsorption isotherms at 77 K. The unpaired electron density of MAC800 was measured in electron spin resonance spectroscopy (ESR), using TEMPOL (4-hydroxy-2,2,6,6-tetramethyl piperidine-1-oxyl) as the reference spin probe. Glycine was converted into ketene at the surface of MAC800, which further underwent radical polymerization to form a low molecular weight ketene polymer (LMKP) of ester structure. The structure and the properties of LMKP were confirmed through 13C, 1H and DEPT nuclear magnetic resonance (NMR) spectroscopy, attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and size exclusion chromatography (SEC). The two hydrophilic drugs namely ciprofloxacin hydrochloride (CPH) and gentamicin sulphate (GS) were chosen for the nanoemulsion preparation and characterization. They were characterized for morphology, interaction of drugs with the polymer and their crystallinity, using HR-TEM, DSC and XRD, respectively. The encapsulation efficiency of the LMKP towards the drugs ciprofloxacin hydrochloride and gentamicin sulphate were 26% and 12%, respectively. The dissolution studies of the nanoemulsion were carried out for the pH 6.5, 7.4 and 8.0. The cytocompatibility studies were done for LMKP as well as nanoemulsion using Hep2 epithelial cells.