K. Chowdoji Rao

Novel thermo/pH sensitive nanogels composed from poly(N-vinylcaprolactam) for controlled release of an anticancer drug

A series of novel nanogels (NGs) with both pH and thermoresponsive properties were synthesised by free radical emulsion polymerisation of N-vinyl caprolactam (VCL) and acrylamidoglycolic acid (AGA). 5-Flurouracil, an anti cancer drug, was successfully loaded into these nanogels via equilibrium swelling method. The encapsulation efficiency of 5-FU was found up to 61%. Here we present the novel potential drug delivery system showing both pH and temperature release of 5-FU. Fourier transforms infrared spectroscopy (FTIR), and differential scanning calorimetric (DSC) examined the structure and morphology of the NGs. Transmission electron microscopy (TEM) indicates the diameter of the NGs to be about 50 nm. The size distribution of NGs was investigated using dynamic light scattering (DLS), the average diameter and polydispersity is 57 nm and 0.194. Interestingly, the in vitro release studies of 5-FU demonstrated the dual nature (pH and temperature) of NGs. The cumulative release data were analysed using an emperical equation to compute the diffusion exponent (n); whose values suggest Fickian diffusion.

Development and Characterization of Chitosan-Poly (Vinyl Pyrrolidone) Blend Microspheres for Controlled Release of Metformin Hydrochloride

Chitosan-Poly (vinyl pyrrolidone), designated as CS-PVP, blend microspheres loaded with an anti-diabetic drug metformin hydrochloride (MH) were prepared using water-in-oil (W/O) emulsion method and used for controlled drug release studies. Microspheres were characterized by Fourier transform infrared spectroscopy (FTIR) to confirm the crosslinking reaction. Scanning electron microscopy (SEM) was also used to assess the surface morphology of particles prepared. The quantities of release of MH-loaded formulations were studied in terms of variation of blend composition and amount of crosslinking agent. DSC and XRD techniques indicated a uniform distribution of MH drug particles in microspheres, whereas SEM suggested the spherical structure of the microspheres with slight rough surface. The in vitro drug release indicated that the particle size and release kinetics depend upon blend composition, amount of cross-linking agent used, and amount of MH present in the microspheres. The prepared microspheres showed 50–82% encapsulation efficiency, which suggested that these IPN microspheres are suitable for controlled release of drugs up to 8 h.

Synthesis and Characterization of pH Sensitive Poly (Hydroxy Ethyl Methacrylate-co-acrylamidoglycolic Acid) Based Hydrogels for Controlled Release Studies of 5-Fluorouracil

Hydrogels were prepared from 2-hydroxy ethyl methacrylate and acrylamidoglycolic acid using N,N’-methylene bis acrylamide as a crosslinking agent in presence of potassium persulfate initiator. The average molecular mass between crosslinks (M c) and polymer-solvent interaction parameter of hydrogels were determined from equilibrium swelling values. Fourier transform infrared spectroscopy of hydrogels shows the confirmation of the formation of co-polymeric hydrogels. Scanning electron microscopy of hydrogels shows the porous network structure. Differential scanning calorimetry and X-ray diffraction were performed to understand the crystalline nature of hydrogel and drug after encapsulation in to hydrogels. In vitro release studies indicated the release of 5-Fluorouracil for more than 12 h.

Biodegradable sodium alginate-based semi-interpenetrating polymer network hydrogels for antibacterial application

A series of biodegradable, semi-interpenetrating polymer network (semi-IPN) hydrogels were synthesized from a combination of carbohydrate polymer and sodium alginate (NaAlg) with acrylamide and dimethyl aminoethyl methacrylate, and crosslinked with N,N-methylenebisacrylamide via radical redox polymerization. The cytocompatibility of the hydrogels with respect to their monomers and semi-IPN hydrogels was evaluated in vitro using cultures of mouse fibroblast cell lines. This study allowed the entrapment of silver nanoparticles (NPs) into semi-IPN hydrogel networks by the in situ reduction of Ag(+) ions using NaBH4 as a reducing agent. UV-visible spectroscopy confirmed the formation of silver NPs in the semi-IPN hydrogel matrix. The formation of silver NPs was also confirmed from a themogravimetric analysis weight loss difference between hydrogel and silver nanocomposite as 32%. The morphology and structure of the AgNPs present in the hydrogel networks were examined by scanning electron microscopy. Transmission electron microscopy revealed silver NPs with a size of ∼5 nm. The silver nanocomposite hydrogel exhibited good antibacterial activity against both gram positive (Staphylococcus aureus) and gram negative (Escherichia coli) bacteria. These results suggest that the hydrogel can be applied as wound dressings and for water purification purposes.

Synthesis and Characterization of Sodium Alginate-g-2-Hydroxyethyl Methacrylate Interpenetrating Beads for Controlled Release of Acebutolol Hydrochloride

Sodium alginate-g-2-hydroxyethyl methacrylate (HEMA) synthesis by free-radical polymerization using K2S2O8 as initiator has been carried out by varying 2-hydroxyethyl methacrylate concentration. Poly(HEMA)-grafted-sodium alginate beads were produced by a solvent evaporation technique using three different concentrations of glutaraldehyde as the cross-linking agent. The graft co-polymer beads were characterized by Fourier transform infrared spectroscopy, differential scanning calorimetry, scanning electron microscopy and X-ray diffraction. Scanning electron microscopy confirmed the spherical nature and surface morphology of particles with a mean particle size of 100 μm. The diffusional exponent (n) values of synthesized beads were found to be in the range 0.1973–0.4764, indicating a Fickian diffusion mechanism with chain relaxation controlled diffusion. Release data have been analyzed using an empirical equation to understand the nature of transport of drug containing solution through the polymeric matrices. The controlled release characteristic of the matrices for acebutolol hydrochloride was investigated in pH 7.4 media. Drug was released in a controlled manner up to 12 h.

Development and Characterization of Semi-IPN Silver Nanocomposite Hydrogels for Antibacterial Applications

Sodium carboxymethyl cellulose/poly(acrylamide-co-2-acrylamido-2-methylpropane sulfonic acid) semi-interpenetrating polymer network (semi-IPN) hydrogels were prepared by using free radical polymerization technique. Silver nanoparticles were formed by reduction of silver nitrate in semi-IPN hydrogels with sodium borohydrate at room temperature. UV-visible spectroscopy, thermogravimetrical analysis, X-ray diffractometry, scanning electron microscopy, and transmission electron microscopy techniques were used to characterize the formation of silver nanoparticles in hydrogels. SEM images indicated clearly the formation of group of silver nanoparticles with size range of 10–20 nm. The sizes of silver nanoparticles were also supported by transmission electron microscopy results. The semi-IPN silver nanocomposite hydrogels reported here might be a potentially smart material in the range of applications of antibacterial activity.

Temperature-responsive poly(N-vinylcaprolactam-co-hydroxyethyl methacrylate) nanogels for controlled release studies of curcumin

A series of nanogels (NGs) were developed from N-vinylcaprolactam and hydroxyethyl methacrylate through free radical emulsion polymerization using methylene bis acrylamide as cross-linker. Curcumin, an anticancer agent was successfully loaded into these NGs via equilibrium in situ method. These NGs were characterized by Fourier transform spectroscopy (FTIR), differential scanning calorimetry (DSC), transmission electron microscopy (TEM), and dynamic light-scattering experimental (DLS) techniques. The formation of co-polymeric NGs was confirmed by FTIR analysis. DSC results reveal that the drug was molecularly dispersed in the NG networks. TEM results indicate the formation of NGs, in a spherical shape, with the size of 150 nm. The DLS results also support the formation and size of NGs. An in vitro release study indicates that the NGs may be potentially useful for targeted drug delivery applications.

Development of Triprolidine-Hydrochloride-Loaded pH-Sensitive Poly(Acrylamide-co-Acrylamidoglycolic Acid) Co-Polymer Microspheres: In Vitro Release Studies

Poly(acrylamide-co-acrylamidoglycolic acid) co-polymeric microspheres cross-linked with N,N-methylene bisacrylamide have been prepared by free radical emulsion polymerization using varying amounts of acrylamide (AAm), acrylamidoglycolic acid (AGA) and N,N-methylene bisacrylamide (NNMBA). Triprolidine hydrochloride (TPH) was loaded into these microspheres during in situ polymerization. The microspheres have been characterized by Fourier Transform Infrared Spectroscopy (FT-IR), to confirm the formation of co-polymer. Differential scanning calorimetry (DSC) and X-ray diffractometry (XRD) were used to understand the drug dispersion in these microspheres. Scanning electron microscopy (SEM) was used to assess the surface morphology of particles prepared. In vitro release of TPH has been studied in terms of composition, amount of cross-linking agent and amount of TPH in the microspheres. The microspheres with different co-polymer compositions have been prepared in yields ranging from 75–80%. DSC and XRD indicated a uniform distribution of TPH particles in microspheres, whereas SEM suggested the formation of distinct spherical shape microspheres. The in vitro drug release indicated release kinetics depending upon co-polymer composition, amount of cross-linking agent used and amount of TPH present in the microspheres. Prolonged and controlled release of TPH was achieved when drug was loaded in the co-polymer and the drug was released in a controlled manner for up to 12 h.

Miscibility Studies of Hydroxypropyl Cellulose/Poly(Ethylene Glycol) in Dilute Solutions and Solid State

The miscibility of Hydroxypropyl cellulose (HPC)/poly(ethylene glycol) (PEG) blends over an extended range of concentrations in water. The viscosity, ultrasonic velocity, and refractive index of the above blend solutions have been measured at 30°C. The interaction parameters such as and μ proposed by Chee and α proposed by Sun have been obtained using the viscosity data to probe the miscibility of the polymer blends. The values indicated that the blends were miscible when HPC content is more than 40% in the blend. The obtained results have been confirmed by the ultrasonic velocity and refractive index studies. The films of the blends were prepared by solution casting method using water as a solvent. The prepared films have been characterized by analytical techniques such as FTIR, DSC, X-RD, and SEM to probe the miscibility of HPC/PEG blends. The compatibility in the above compositions may be due to the formation of H-bonding between hydroxyl groups of HPC and etheric oxygen atom of PEG molecules.

Characteristic Studies of Ligno-Cellulosic Fabric Grewia tenax

The uniaxial natural fabric Grewia tenax was treated with sodium hydroxide, acetic acid, poly(vinyl alcohol) (PVA), and polycarbonate (PC) solutions, and characterized by a variety of techniques. Differential scanning calorimetry and thermogravimetry were used to characterize the thermal behavior of the fabric. Attenuated total reflectance-infrared spectroscopy was used to characterize the fabric constituents. The morphology of the fabric was studied using scanning electron microscopy technique. X-ray diffraction studies were carried out to determine crystallinity of the fabric. Chemical composition and tensile properties of the fabric samples were also studied. Significant changes were observed in the fabric with various treatments. Tensile properties of the fabric were observed to have improved with PVA and PC treatments. The tensile strength of the fabric was found to be decreased on alkali and acetic acid treatments. The authors conducted all these tests before and after treatments except the chemical composition.