ORIGINAL PAPER Synthesis and characterisation of Gossypium hirsutum seeds extract nanoencapsulated in silica microparticles C. V. Moraru 1,2 • K. Magyari 1 • M. Tamasan 1 • S. Suarasan 1 • D. Muntean 2 • L. Vlase 2 • F. Loghin 2 • S. Simon 1 Received: 30 May 2015 / Accepted: 3 August 2015 Ó Springer Science+Business Media New York 2015 Abstract Nanoencapsulation of pharmaceutically active natural compounds into porous systems through sol–gel method leads to new drug delivery materials with sustained release behaviour of the entrapped pharmaceuticals. Prop- erties of inorganic sol–gel-derived silica microparticles loaded with cotton (Gossypium hirsutum) seeds extract are reported. Xerogels obtained by heat or freeze drying were investigated by X-ray diffraction, dynamic light scattering, differential thermal analysis (DTA)/thermogravimetric analysis (TGA), UV–Vis and fluorescence spectroscopy. Effects of drying process on both silica particles and plant extract were evaluated. In vitro release was studied in release media with pH 1.1 and 7.4. The investigated bio- composite systems display a biphasic release profile wherein the diffusion prevails over the dissolution. Graphical Abstract Keywords Sol–gel  Silica microparticles  Cotton seeds extract  Nanoencapsulation  Nano in micro  Release kinetics 1 Introduction In recent years, the interest for sol–gel-derived materials intensely increased due to their flexible synthesis protocol allowing the control of morphology, porosity and size of particles [1–7]. These materials can be efficiently exploited as matrices for different pharmaceutically active compounds [8]. Therefore, new opportunities in biomed- ical industry can result from the synthesis of porous materials loaded with pharmaceutically active natural compounds. & S. Simon simion.simon@phys.ubbcluj.ro 1 Faculty of Physics and Institute of Interdisciplinary Research in Bio-Nano-Sciences, Babes-Bolyai University, Cluj-Napoca, Romania 2 Faculty of Pharmacy, Iuliu Hatieganu University of Medicine and Pharmacy, Cluj-Napoca, Romania 123 J Sol-Gel Sci Technol DOI 10.1007/s10971-015-3828-8