K. Vimala

Fabrication of porous chitosan films impregnated with silver nanoparticles: A facile approach for superior antibacterial application

The present investigation involves the synthesis of porous chitosan-silver nanocomposite films in view of their increasing areas of application in wound dressing, antibacterial application, and water purification. The entire process consists of three-steps including silver ion-poly(ethylene glycol) matrix preparation, addition of chitosan matrix, and removal of poly(ethylene glycol) from the film matrix. Uniform porous and brown colour chitosan films impregnated with silver nanoparticles (AgNPs) were successfully fabricated by this facile approach. Both, poly(ethylene glycol) (PEG) and chitosan (CS) played vital roles in the reduction of metal ions into nanoparticles (NPs) as well as provided good stability to the formed nanoparticles. The developed porous chitosan-silver nanocomposite (PCSSNC) films were characterized by UV-vis and FTIR spectroscopy, and thermogravimetric analysis for the confirmation of nanoparticles formation. The morphology of silver nanoparticles in nanocomposite films was tested by optical microscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The embedded AgNPs were clearly observed throughout the film in SEM and the extracted AgNPs from the porous chitosan-silver nanocomposite showed approximately 12nm in TEM. Improved mechanical properties were observed for porous chitosan-silver nanocomposite than for chitosan blend (CSB) and chitosan-silver nanocomposite (CSSNC) films. Further, the examined antibacterial activity results of these films revealed that porous chitosan-silver nanocomposite films exhibited superior inhibition.

Controlling of silver nanoparticles structure by hydrogel networks

Silver nanoparticles are the most widely used antibacterial agents with a number of advantages. The higher degree of biocompatibility and long-term antibacterial activity can be achieved with hydrogel-silver nanoparticles. In this work, a simple and facile synthetic strategy is developed to control the size and shape of the silver nanoparticles within the hydrogel networks. The variation in cross-link density of the polymer network has been found not only to control the size of the nanoparticles between 1 and 10nm, but it also regulates shape of the nanostructures such as nanorods, nanocubes, etc. This approach takes the advantage of the existing free-space between the networks of hydrogels that not only acts as a template for nucleation of particles but also provides long term stability. Further, nanoparticles can be recovered at any time from the hydrogel networks. These hybrid nanocomposites release nanoparticles with time which can eventually promote for antibacterial application. It can be inferred from the study that fine tuning of the hydrogel synthetic parameters will enhance the possibilities of desired nano-product tailor made for particular applications.

Synthesis and Characterizations of Macroporous Poly(acrylamide-2-acrylamido-2-methyl-1-propanesulfonic acid) Hydrogels for In Vitro Drug Release of Ranitidine Hydrochloride

Macroporous hydrogels were prepared with acrylamide (AM) and 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) as well as with anhydrous dextrose (AD) as porogen by crosslinking with N,N1-methylenebisacrylamide (MBA). The chemical structure of hydrogels is characterized by Fourier transform infrared (FTIR) spectroscopy. Morphological studies done by scanning electron microscopy (SEM) showed the macroporous nature of the hydrogels. Swelling studies of hydrogels were done in distilled water, in aqueous NaCl solution and in different pH solutions. In addition, drug release studies of selected macroporous hydrogels (DAMPS1, DAMPS4, DAMPSM1 and DAMPSM3) are also investigated.

Poly(acrylamide-chitosan) Hydrogels: Interaction with Surfactants

Semi-interpenetrating hydrogels were prepared from hydrophilic acrylamide and cationic natural biopolymer chitosan, N,N1-methylenebisacrylamide and water-soluble redox initiating system (ammonium persulfate/N,N,N1,N1-tetramethylethylenediamine). The interaction of these hydrogels with different surfactants such as sodiumdodecylsulphate (SDS, anionic), N-cetyl N,N,N-trimethyl ammonium bromide (CTA, cationic) and Tween20 (T20 non-ionic) was studied. The chemical structure of the hydrogels treated with surfactant was characterized by FTIR spectroscopy and the morphology of hydrogels was characterized by scanning electron microscopy (SEM). The thermal properties of surfactant-treated hydrogels were evaluated by TGA analysis.

Surfactant-Modified Poly(acrylamide-co-acrylamido propane sulphonic acid) Hydrogels

Recent advances in drug delivery have been directed towards the design of a number of intelligent systems for the treatment of various diseases. In this regard, we developed novel surfactant-modified hydrogels which are synthesized from acrylamide (AM) and acrylamido propane sulphonic acid (AMPS), in the presence of a surfactant (Latemul PD-104) using ammonium persulfate/N,N,N′,N′–tetramethylethylene diamine (APS)/(TMEDA) as an initiating system and N,N′-methylenebisacrlyamide (MBA) as a crosslinker. The hydrogel formation was confirmed by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The variation in the hydrogel networks formation employing different levels of synthetic parameters was verified by swelling studies. Influences of salt, biological fluids, and buffer solutions on the developed systems were also investigated. It was found that, compared to PAM hydrogel, all the surfactant-modified hydrogels were responsive towards salt concentration and pH. A robust drug release behavior was observed from surfactant-modified hydrogel systems.

Cell Encapsulation in Polymeric Self-Assembled Hydrogels

Over the past two decades, the rapid development of cells encapsulated hydrogels and self-assembled hydrogels have been sources of attraction in several biomedical fields in order to control various aspects of human-related diseases and tissue regeneration and repair (surgery). Polymer hydrogels are composed of several natural, synthetic polymers, and cross-linkers in order to form tissue-like elasticity, nontoxicity, biodegradability, biocompatibility, and swelling ability, which enhance their applicability in advanced medicine and cell biological applications. This chapter covers several important natural and synthetic polymers widely used as hydrogels and self-assembled hydrogels for cell encapsulation. Cells encapsulated self-assembled hydrogels, their recent developments, and their significances in various medical applications are also discussed.