M. Geetha Devi

Studies on encapsulation of Rifampicin and its release from chitosan-dextran sulfate capsules

Biodegradable capsules of size around 350 nm were prepared by layer-by-layer (L-b-L) assembly of oppositely charged chitosan and dextran sulfate on silica particles and the subsequent removal of template. The resulting capsules were loaded with rifampicin, an anti-tuberculosis drug under modest conditions, as demonstrated by scanning electron microscopy (SEM). Maximum encapsulation of rifampicin was found to be about 82 μg at 25 °C and pH of 3. Release studies were done in-vitro mode by semiautomatic release protocol, with different pH solutions in water and phosphate buffered saline (PBS). The microcapsules exhibited a slow and sustained release over 72 hours and maximum release was obtained at a pH of 1.2 in water and a pH of 7.4 in PBS. The size of silica particle was analyzed by dynamic light scattering method. Scanning electron microscopy (SEM) measurements showed the surface morphology of the hollow capsules. UV spectroscopy was employed to monitor the drug release processes in both solutions. The kinetics of drug release mechanism was studied using Ritger-Peppas and Higuchi models.

Synthesis, characterization and application of nanoparticles in wastewater treatment

ABSTRACT The present research work focused on the synthesis of silica nanoparticles and their surface modifications using layer-by-layer (L-b-L) coating with low molecular-weight chitosan. The surface-modified nanoparticles were employed in the treatment of textile industry effluent. A series of batch experimental studies were performed in the treatment of textile industry effluent by varying the effluent solution pH, contact time, dosage of nanoparticles and stirring speed. Characterizations of the synthesized nanoparticles before and after surface modification are performed using Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Analysis, Fourier-Transform Infrared Spectroscopy (FTIR) and Dynamic Light Scattering (DLS). The experimental observations showed that the sizes of both silica and surface-modified particles are less than 335 nm. The effectiveness of nanoparticles in the treatment of textile mill effluent was studied by assessing the Chemical Oxygen Demand (COD), Total Dissolved Solids (TDS), Total Suspended Solids (TSS), Dissolved Oxygen (DO), Turbidity and Conductivity before and after treatment. The experimental result demonstrates that the surface-modified particles could effectively reduce the pollutants from textile industry effluent.

Encapsulation and Release of Moxifloxacin Hydrochloride in Chitosan–Dextran Sulphate Microcapsules

Abstract In the present work, multilayer microcapsules of size 350 nm were prepared with layer-by-layer assembly of oppositely charged chitosan and dextran sulphate on silica template. The monodisperse silica particles (310 nm) with fine spherical shape were successfully synthesized by Stobers method. Dissolution of silica particles in HF leads to the formation of hollow capsules. The resulting capsules were found to be able to effectively load moxifloxacin hydrochloride in the interior of the capsules under modest conditions without addition of other reagents, as demonstrated by scanning electron microscopy. Parameters affecting loading and release such as pH and initial concentrations were investigated. Release studies were performed in in-vitro mode with a semi-automatic release protocol, with different pH solutions in water and phosphate buffered saline. The size of silica particles was analysed by dynamic light scattering method. Scanning electron microscopy and energy dispersive X-ray spectroscopy measurements proved the surface morphology and purity of the hollow capsules from the core material. The kinetics of drug release mechanism was studied using Peppas and Higuchi models.