R. Rakesh Kumar

Fabrication of chitosan microspheres using vanillin/TPP dual crosslinkers for protein antigens encapsulation.

Microspheres were prepared from water soluble chitosan using dual vanillin/TPP crosslinkers. Placebo (C1), Bovine serum albumin (BSA) (C2), monovalent tetanus toxoid (TT) (C3) and divalent tetanus (TT) and diphtheria toxoids (DT) (C4) encapsulated microspheres were studied in terms of size (1-4 μm), encapsulation efficiency (75-80%), swelling and mucoadhesion (56-68%). FT-IR, TGA, XRD and SEM characterization of microspheres suggested specific interaction, more thermal stability, amorphous nature and rough surfaces of encapsulated microspheres. EDS confirmed the co-crosslinking and ninhydrin tests were showing higher crosslinking density. Zeta potential was 47.7 to 66.2 +mV indicating the potential stability of the colloidal system. Equilibrium adsorption isotherms described encapsulated microspheres followed the Langmuir isotherm model, suggesting monolayer adsorption of the mucin on microspheres. In-vitro release studies up to four weeks indicated zero order kinetics and obeyed swelling-controlled super case II transport release mechanism. Thus, the present study could be helpful in developing the multivalent oral vaccine.

Nanocrystal Technology in the Delivery of Poorly Soluble Drugs: An Overview

Extensive attempts to overcome problems related to solubility of drugs for maximizing bioavailability at targeted sites in the body have been made. The issue of drug solubility appears to attract the continued interest of pharmaceutical manufacturers. In this context, nanocrystallization has emerged as an important tool. In the present review, the authors discuss the advantages of nanocrystallized drugs and examine the products available in the market as well as drugs in the pipeline using nanocrystal-based formulations, which are being developed by pharmaceutical companies for drug delivery.

Morphology controlled synthesis of Al doped ZnO nanosheets on Al alloy substrate by low-temperature solution growth method

We report the morphology-controlled synthesis of aluminium (Al) doped zinc oxide (ZnO) nanosheets on Al alloy (AA-6061) substrate by a low-temperature solution growth method without using any external seed layer and doping process. Doped ZnO nanosheets were obtained at low temperatures of 60–90 °C for the growth time of 4 hours. In addition to the synthesis, the effect of growth temperature on the morphological changes of ZnO nanosheets is also reported. As-synthesized nanosheets are characterized by FE-SEM, XRD TEM and XPS for their morphology, crystallinity, microstructure and compositional analysis respectively. The doping of Al in ZnO nanosheets is confirmed with EDXS and XPS. Furthermore, the effect of growth temperature on the morphological changes was studied in the range of 50 to 95 °C. It was found that the thickness and height of the nanosheets varied with respect to the growth temperature. The study has given an important insight into the structural morphology with respect to the growth temperature, which in turn enabled us to determine the growth temperature window for the ZnO nanosheets. These Al doped ZnO nanosheets have potential application possibilities in gas sensors, solar cells and energy harvesting devices like nanogenerators.

Low temperature VLS growth of ITO nanowires by electron beam evaporation method

Indium tin oxide (ITO) nanowires were grown at a lower substrate temperature of 400 °C via Au-catalyzed vapor–liquid–solid (VLS) growth mechanism by electron beam evaporation method. The grown nanowires had length and diameter of 0.8–1.2 μm and 20–50 nm, respectively for growth duration of 20 min. Transmission electron microscope studies confirm the single crystalline nature of the nanowires, and energy dispersive spectroscopy studies on the individual nanowires also confirm that nanowire growth proceeds via Au-catalyzed VLS growth mechanism. Transition in the growth mechanism from Au-catalyzed VLS growth to self-catalyzed VLS growth was observed as the growth temperature changed from 400 to 200 °C. Self-catalytic VLS growth as well as Au catalyzed VLS growth was observed in a growth temperature window of 350–250 °C. This transition in the growth mechanism is mainly due to differences in the growth kinetics of Au-VLS and self-catalyzed VLS mechanism. These results indicate a good understanding of ITO nanowires growth by e-beam evaporation method. Diameters of the nanowires were tuned in a broad range of 20–90 nm by changing the Au catalyst layer thickness. This catalyst-assisted and low temperature growth method can be implemented for precise diameter controlled synthesis of ITO nanowires with mono dispersed gold catalyst particles instead of Au catalyst film to tune the optical properties of the nanowires.

Antibody persistence of two pentavalent DTwP–HB–Hib vaccines to the age of 15–18 months, and response to the booster dose of quadrivalent DTwP–Hib vaccine

OBJECTIVES Antibody persistence in children following three doses of primary vaccination with diphtheria, tetanus, whole-cell-pertussis (DTwP), hepatitis B, and Haemophilus influenzae type b (Hib) vaccines (SIIL Pentavac vaccine vs. Easyfive(®) of Panacea Biotec), and response to the booster dose of DTwP-Hib (Quadrovax(®)) vaccine. METHODS Children who completed their primary immunization were assessed for antibodies at 15-18 months of age, and then given a booster dose of DTwP-Hib vaccine. Reactogenicity and safety of the booster dose was evaluated. RESULTS Both pentavalent vaccines demonstrated a good immune response at 15-18 months. Following the booster dose, all vaccinated subjects achieved protective titers against diphtheria, tetanus and Hib, whereas the response to pertussis antigen was ~78%. Fever and irritability was noted in 24%, local pain in 51%, and swelling in 36% of the children following booster dose. CONCLUSIONS Primary immunization with either pentavalent vaccine induced an excellent immunity lasting till the second year of life. A booster dose with DTwP-Hib (Quadrovax(®)) vaccine effectuated a good anamnestic response to all vaccine components, being specially strong for Hib in children previously vaccinated with SIIL liquid pentavalent vaccine (Pentavac(®)). Also, the safety profile of SIIL quadrivalent vaccine (Quadrovax(®)) administered as booster dose was acceptable.

Point mutation Gln121-Arg increased temperature optima of Bacillus lipase (1.4 subfamily) by fifteen degrees.

Small molecular weight Bacillus lipases are industrially attractive because of its alkaline optimum pH, broad substrate specificity and production in high yield by overexpression both in Escherichia coli and Bacillus subtilis. Its major limitation of being mesophilic in nature is constantly targeted by laboratory evolution studies. Herein metagenomically isolated Bacillus LipJ was randomly evolved by error prone PCR and library of variants were screened for enhanced thermostability. Point mutant Gln121Arg was extensively characterized and it showed dramatic shift of Temp. opt to 50°C compared to 37°C for parent enzyme. Thermostability studies at 45°C and 50°C determined six fold increase in half life for point variant Gln121Arg compared to LipJ. Circular dichroism (CD) and tryptophan fluorescence study established enhanced thermostability of Gln121Arg. Specific activity of point variant Gln121Arg was comparable to wild type with increased substrate affinity (Km reduced). Reduced kcat for variant Gln121Arg infer that kinetic and catalytic efficiency of mutant was compromised. Structural implications by homolog modelling predicted Gln121 to be placed within longest loop of the structure at surface. Localization of loop due to additional polar interactions by Arg121 to protein core defines molecular basis of enhanced thermostability of random point variant Gln121Arg.

Tartrate/tripolyphosphate as co-crosslinker for water soluble chitosan used in protein antigens encapsulation.

In drug delivery research, several toxic chemical crosslinkers and non-toxic ionic crosslinkers have been exploited for the synthesis of microparticles from acetic acid soluble chitosan. This paper hypothesized the implementation of sodium potassium tartrate (SPT) as an alternative crosslinker for sodium tripolyphosphate (TPP) and SPT/TPP co-crosslinkers for synthesis of the microparticles using water soluble chitosan (WSC) for encapsulation of Bovine serum albumin (BSA) as a model protein, and Tetanus toxoid (TT) as a model vaccine. The crosslinking was confirmed by FT-IR, SEM with EDS. The XRD entailed molecular dispersion of proteins and thermal analysis confirmed the higher stability of STP/TPP co-crosslinked formulations. The resultant microparticles were exhibiting crosslinking degree (52-67%), entrapment efficiency (72-80%), particle size (0.3-1.7μm), zeta potential (+24 to 46mV) and mucoadhesion (41-68%). The superiority of SPT over TPP was confirmed by higher crosslinking degree and entrapment efficiency. However, co-crosslinking were advantageous in higher regression values for Langmuir adsorption isotherm, slower swelling tendency and extended 30days controlled in-vitro release study. TT release obeyed the Quasi-Fickian diffusion mechanism for single and cocrosslinked formulations. Overall, in crosslinking of chitosan as biological macromolecules, STP/TPP may be alternative for single ionic crosslinked formulations for protein antigen delivery.

Estimation of child vaccination coverage at state and national levels in India.

Abstract Objective To review the data, for 1999–2013, on state-level child vaccination coverage in India and provide estimates of coverage at state and national levels. Methods We collated data from administrative reports, population-based surveys and other sources and used them to produce annual estimates of vaccination coverage. We investigated bacille Calmette–Guérin vaccine, the first and third doses of vaccine against diphtheria, tetanus and pertussis, the third dose of oral polio vaccine and the first dose of vaccine against measles. We obtained relevant data covering the period 1999–2013 for each of 16 states and territories and the period 2001–2013 for the state of Jharkhand – which was only created in 2000. We aggregated the resultant state-level estimates, using a population-weighted approach, to give national values. Findings For each of the vaccinations we investigated, about half of the 253 estimates of annual coverage at state level that we produced were based on survey results. The rest were based on interpolation between – or extrapolation from – so-called anchor points or, more rarely, on administrative data. Our national estimates indicated that, for each of the vaccines we investigated, coverage gradually increased between 1999 and 2010 but then levelled off. Conclusion The delivery of routine vaccination services to Indian children appears to have improved between 1999 and 2013. There remains considerable scope to improve the recording and reporting of childhood vaccination coverage in India and regular systematic reviews of the coverage data are recommended.

Thirty-degree shift in optimum temperature of a thermophilic lipase by a single-point mutation: effect of serine to threonine mutation on structural flexibility

In order to understand the molecular basis of cold adaptation, we have used directed evolution to transform a thermophilic lipase LipR1 into its psychrophilic counterpart. A single round of random mutagenesis followed by screening for improved variants yielded a mutant with single-point mutation LipR1M1 (S130T), with optimum activity at 20 °C. Its activity at 50 °C is only 20% as compared to wild type (100%). It showed catalytic rate constant (kcat) 3 times higher and a catalytic efficiency (kcat/Km) 4 times that of wild type. Circular dichroism and fluorescence studies also supported our observation of mutant structural flexibility. Structure analysis using homology models showed that Threonine 130 is exposed to solvent and has lost H-bond interaction with neighboring amino acid, thereby increasing flexibility of this lipase structure.

Synthesis of ZnO nanorods on a flexible Phynox alloy substrate: influence of growth temperature on their properties

A novel flexible alloy substrate (Phynox, 50 mm thick) was used for the synthesis of zinc oxide (ZnO) nanorods via a low-temperature solution growth method. The growth of ZnO nanorods was observed over a low temperature range of 60-90 degrees C for a growth duration of 4 hours. The as-synthesized nanorods were characterized using field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) for their morphology, crystallinity, microstructure and composition. The as-grown ZnO nanorods were observed to be relatively vertical to the substrate. However, the morphology of the ZnO nanorods in terms of their length, diameter and aspect ratio was found to vary with the growth temperature. The morphological variation was mainly due to the effects of the various relative growth rates observed at the different growth temperatures. The growth temperature influenced ZnO nanorods were also analyzed for their wetting (either hydrophobic or hydrophilic) properties. After carrying out multiple wetting behaviour analyses, it has been found that the as-synthesized ZnO nanorods are hydrophobic in nature. The ZnO nanorods have potential application possibilities in self-cleaning devices, sensors and actuators as well as energy harvesters such as nanogenerators.