Sengottuvelan Balasubramanian

Gold nanoparticle conjugated PLGA–PEG–SA–PEG–PLGA multiblock copolymer nanoparticles: synthesis, characterization, in vivo release of rifampicin

A series of succinate linearly linked PLGA-PEG-SA-PEG-PLGA multiblock copolymers were synthesized using direct melt polycondensation and characterized using inherent viscosity, gel permeation chromatography (GPC), FTIR and 1H-NMR spectroscopy techniques. Gold nanoparticles (AuNPs) were synthesized using an as-synthesized citrate-PEG (CPEG) hybrid dendron, which acts as a reducing agent as well as a stabilizing agent. The CPEG capped AuNPs were characterized using UV-visible spectroscopy and TEM analysis. The Au-conjugated PLGA-PEG-SA-PEG-PLGA multiblock copolymer NPs were loaded with the tuberculosis drug rifampicin (RIF) using ultrasonication followed by solvent evaporation and were characterized by TEM, powder XRD and XPS analyses. The RIF loading efficiency and percentage drug content of RIF loaded Au-conjugated multiblock copolymer NPs were evaluated using UV-visible spectroscopy. The RIF loading efficiency and RIF content of the AuNP conjugated multiblock copolymer NPs were 41.8-75.7% and 11.5-17.7% respectively. The in vivo drug release studies in male Wistar rats show that AuNP conjugated multiblock copolymer NPs exhibit drug release up to 240 h. The nanoconjugates exhibit 18.13-29.41 μg mL-1 of Cmax with a delayed Tmax of 72 h and the relative bioavailability is increased to 107-190.

Isoniazid loaded core shell nanoparticles derived from PLGA-PEG-PLGA tri-block copolymers: in vitro and in vivo drug release.

A series of biodegradable low molecular weight PLGA-PEG-PLGA tri-block copolymers have been synthesized in powder form. The anti-tuberculosis drug Isoniazid (INH) loaded polymeric core-shell nanoparticles (CSNPs) have been prepared by sonication followed by water-in-oil-in-water (w/o/w) double emulsification technique. The nanoparticles (NPs) have been characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), powder X-ray diffraction (XRD) and X-ray photo electron spectroscopic (XPS) techniques. The drug loaded CSNPs were found to be 150-400 nm in size with spherical shape. The drug loading efficiency and drug content of the polymer NPs were determined by UV-vis spectrophotometry. The drug loading efficiency and drug content of the NPs were (12.8-18.67%) and (6.4-8.9%) respectively. The in vitro release behavior of the polymer NPs has been investigated by UV-vis spectrophotometry and the release kinetics mechanism has been evaluated by Korsemeyer-Peppas (KP) and Higuchi models. The in vitro release studies show initial burst release followed by controlled and uniform release for longer duration. The pharmacokinetic studies show that the INH bioavailability of INH loaded CSNPs is 28 fold higher than that of free INH and also the CSNPs show sustained drug release for longer duration.

Novel PLGA-based nanoparticles for the oral delivery of insulin.

Background Insulin is the drug therapy for patients with insulin-dependent diabetes mellitus. A number of attempts have been made in the past to overcome the problems associated with the oral delivery of insulin, but with little success. Orally administered insulin has encountered with many difficulties such as rapid degradation and poor intestinal absorption. The potential use of D-α-tocopherol poly(ethylene glycol) 1000 succinate (TPGS)-emulsified poly(ethylene glycol) (PEG)-capped poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) was investigated for sustained delivery of insulin (IS). Objective To investigate the efficacy of TPGS-emulsified PEG-capped PLGA NPs (TPPLG NPs) as a potential drug carrier for the oral delivery of insulin. Methods A series of biodegradable low-molecular-weight PLGA (80/20 [PLG4] and 70/30 [PLG6]) copolymers were synthesized by melt polycondensation. The commercial insulin-loaded TPGS-emulsified PEG-capped PLGA NPs (ISTPPLG NPs) were synthesized by water–oil–water emulsion solvent evaporation method. The physical and chemical properties of PLGA copolymers, particle size, zeta potential, and morphology of the NPs were examined. The in vivo studies of ISTPPLG NPs were carried out in diabetic rats by oral administration. Results The maximum encapsulation efficiency of ISTPPLG6 NPs was 78.6%±1.2%, and the mean diameter of the NPs was 180±20 nm. The serum glucose level was significantly (twofold) decreased on treatment with ISTPPLG NPs, and there was a threefold decrease with insulin-loaded PLGA (70/30) NPs when compared to that of free insulin-treated diabetic rats. The results show that the oral administration of ISTPPLG6 NPs is an effective method of reducing serum glucose level for a period of 24 hours. Histopathological studies reveal that ISTPPLG NPs could restore the damage caused by streptozotocin in the liver, kidneys, and pancreas, indicating its biocompatibility and regenerative effects. Conclusion ISTPPLG6 NPs can act as potential drug carriers for the oral delivery of insulin.

One pot green synthesis of Ag, Au and Au–Ag alloy nanoparticles using isonicotinic acid hydrazide and starch

Gold-silver alloy nanoparticles were synthesized via chemical reduction of varying mole fractions of chloroauric acid (HAuCl4) and silver nitrate (AgNO3) by environmentally benign isonicotinic acid hydrazide (INH) in the presence of starch as a capping agent in aqueous medium. The absorption spectra of Au-Ag nanoparticles show blue shift with increasing silver content indicating the formation of alloy nanoparticles. When the Ag content in the alloy decreases the size of the nanoparticles increases and as a result of which the oxidation potential also increases. The emission maximum undergoes a red shift from 443 to 614 nm. The nanoparticles are monodisperse and spherical with an average particle size of 3-18 nm. The catalytic behavior of alloy nanoparticles indicate that the rate constant for the reduction of 4-nitro phenol to 4-amino phenol increases exponentially from metallic Ag to metallic Au as Au content increases in the Au-Ag alloy nanoparticles.

4′-functionalized 2,2′:6′,2′′ terpyridine ruthenium (II) complex: a nanocrystalline TiO2 based solar cell sensitizer

The synthesis of an Ru(II) complex derived from 4-(4-methacryloyloxymethylphenyl)-2,2:6,2 terpyridine ligand, together with its spectral and electrochemical properties, has been described. The application of this complex, which does not possess the usual anchoring groups like carboxylate or phosphate, in a dye sensitized nanocrystalline TiO2 solar cell has indicated a short circuit current of 0.252 mA, an open circuit potential of 377 mV with an overall efficiency of 3.63%. The overall conversion efficiency of the system remains stable for a long period due to the efficient electron injection into the conduction band during light absorption. The high resolution scanning electron microscopy picture reveals a three-dimensional network of interconnected nanoscale particles, while x-ray diffraction studies show that the particle size is 21 nm.

Synthesis, characterization and application of acryloyl chitosan anchored copolymer towards algae flocculation

A novel water soluble flocculant AC-g-P(DMC-MACPPC) was synthesized by free radical polymerization of [2-(methacryloyloxy) ethyl] trimethylammonium chloride (DMC) and 4-methacryloyl 1-cyclopentyl piperazinium chloride (MACPPC), grafted on to acryloyl chitosan (AC). The grafting of copolymer was confirmed by DRS-UV, FTIR, NMR, Raman, XRD and XPS spectral techniques. The AC-g-P(DMC-MACPPC) exhibits higher flocculation efficiency towards harvesting of C. vulgaris micro algae, when compared to that of copolymer P(DMC-MACPPC) and homo polymer PMACPPC. The higher efficiency exhibited by the grafted copolymer can be attributed to the increase in positive charge and molecular weight after grafting on to acryloyl chitosan. The grafted copolymer AC-g-P(DMC-MACPPC) is very easy to synthesize, economical and water soluble which makes it a promising flocculant in the algae harvesting process.

Synthesis, characterization and photocatalytic studies of mesoporous silica grafted Ni(II) and Cu(II) complexes

Mesoporous silica grafted nickel(II) and copper(II) complexes of a Schiff base ligand were synthesized. Functionalization of the ligand was achieved by Schiff base condensation of 3-APTES and O,O′-mono methylene bis(salicylidene). The Schiff base moiety was subsequently grafted with MCM41, followed by complexation with metal salts. The compounds were characterized by spectroscopy (Fourier transform infrared spectroscopy (FTIR), diffuse reflectance UV-Vis spectroscopy (DRS/UV-Vis), X-ray diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS)), thermal analysis (Thermo Gravimetric Analysis (TGA)) microscopy (High Resolution Transmission Electron Microscopy (HRTEM)) and surface Brunauer–Emmett–Teller (BET) method, N2-sorption isotherms analysis. The compounds were employed in the photo oxidation of Methyl Orange (MO) and Reactive Red198 (RR). The copper complex exhibits higher activity in the photo degradation of the dyes. The reusable photocatalysts show comparable activity to that of fresh catalyst without loss of their catalytic nature.

Synthesis of chitosan capped copper oxide nanoleaves using high intensity (30 kHz) ultrasound sonication and their application in antifouling coatings

The synthesis of chitosan capped copper oxide nanoleaves (CCCO NLs) was carried out under three different reaction conditions viz. 1) room temperature, 2) 70°C and 3) high intensity ultrasound (30kHz) sonication method and it has been found that the high intensity ultrasound (30kHz) sonication is the best method when compared to other two methods. The advantages of the present synthetic method are: i) easy one step process, ii) lesser reaction time, iii) good yield, iv) reproducible and v) calcination is not required. The resulting chitosan capped copper oxide nanoleaves were characterized by Diffuse Reflectance UV-Visible Spectroscopy (DRS), Fourier Transform Infra-Red Spectroscopy (FT-IR), X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), Field Emission Scanning Electron Microscopy (FESEM), High Resolution Transmission Electron Microscopy (HRTEM) and Thermo gravimetric analysis (TGA). The CCCO NLs were blended with commercial paints such as polyurethane clear, polyurethane white and acrylic emulsion and applied on to three different surfaces (wood, mild steel and cement slab panels). The hydrophilicity of CCCONP coated panels was analyzed by water contact angle measurement and their antifouling behavior was investigated against three different green and marine algae viz. Arthrospira, Chlorella and Amphora. The antifouling efficiency of the CCCO NLs against the algae was found to be 78-92%.

κ-Carrageenan: An effective drug carrier to deliver curcumin in cancer cells and to induce apoptosis

The current study is to develop a natural drug carrier with seaweed derived polymers namely κ-Carrageenan (κ-Car) for drug delivery applications. κ-Car is a natural polysaccharide which derived from edible red seaweeds, they are easily available, non-toxic, cost effective, biodegradable and biocompatible nature. Curcumin (Cur) is a yellow-orange polyphenol existing in turmeric, which is predominantly used as spice and food coloring agent. The ultimate use of polymeric composites, especially those composed of natural polymers, has become a very interesting approach in recent drug delivery applications, due to their non-toxicity and biological origin. In this study the primary approach which depends on the loading of Curcumin into κ-Carrageenan was accomplished, and which (κ-Car-Cur) an active drug carrier was developed for drug delivery against selected lung cancer cells (A549). Thus, the κ-Car-Cur was synthesized by solvent evaporation method followed by freeze drying, and it was further characterized. From this study, it has been reported that the high encapsulation efficiency, good stability, and successful release of Cur from the carrier (κ-Car) was achieved. The drug release was more active at acidic pH 5.0 with the cumulative release of 78%, which is the favorable condition present in tumor microenvironments. The in vitro cellular applications studies of κ-Car-Cur demonstrated that, κ-Car-Cur composites induced higher cytotoxicity against selected cancer cells than free Cur and effectively involved to trigger cellular apoptosis in A549 cancer cells. Further, it was also possessed that inhibition of cell growth and changes in metabolic activity of cancer cells are the unique characteristic features of cellular apoptosis, through reactive oxygen species (ROS) generation. It also observed that there was a decrease in mitochondrial membrane potential (ΔψmΔψm) which leads to a cellular apoptosis during treatment with κ-Car-Cur. Hence, the study outcomes may provide the potential outline for the use of κ-Car-Cur as a promising tool to deliver drugs at intracellular level.

Zeolite encapsulated active metal composites and their photocatalytic studies for rhodamine-B, reactive red-198 and chloro-phenols

Niobium (Nb), tantalum (Ta) and palladium (Pd) were impregnated in the cavities of a zeolite by the ion exchange method. The impregnation and composites stability were investigated by FTIR, DRS/UV-visible, XRD, XPS, BET, N2 adsorption isotherms, AAS, FESEM/EDX, TEM, TGA and particle size. The composites denoted as PdY, NbPdY and TaPdY were used as visible light driven photocatalysts in the degradation of Rhodamine-B (RhB), reactive red-198 (RR), 2-chloro phenol (2CP) and 4-chloro phenol (4CP) under visible light irradiation. The composites catalytic ability was determined by UV-visible absorption spectral analysis. The TaPdY, and NbPdY exhibit superior degradation kinetics when compared to that of PdY and NaY, due to the presence of refractory metals such as Nb(V) and Ta(V) in the zeolite cavities. The percentage of degradation and rate of reaction is more for NbPdY and TaPdY. The photo oxidation reaction follows pseudo-first order reaction kinetics and this might be due to the fixed concentration of the reactants, photocatalysts and reaction medium. The NbPdY and TaPdY catalysts are recoverable and reusable for up to five cycles of repeated usage. The recovered and reusable catalyst shows comparable activity with that of the fresh catalyst.