Jonnalagadda Raghava Rao

Application of a chemically modified green macro alga as a biosorbent for phenol removal.

Phenol and substituted phenols are toxic organic pollutants present in tannery waste streams. Environmental legislation defines the maximum discharge limit to be 5-50 ppm of total phenols in sewers. Thus the efforts to develop new efficient methods to remove phenolic compounds from wastewater are of primary concern. The present work aims at the use of a modified green macro alga (Caulerpa scalpelliformis) as a biosorbent for the removal of phenolic compounds from the post-tanning sectional stream. The effects of initial phenol concentration, contact time, temperature and initial pH of the solution on the biosorption potential of macro algal biomass have been investigated. Biosorption of phenol by modified green macro algae is best described by the Langmuir adsorption isotherm model. Biosorption kinetics of phenol onto modified green macro algal biomass were best described by a pseudo second order model. The maximum uptake capacity was found to be 20 mg of phenol per gram of green macro algae. A Boyd plot confirmed the external mass transfer as the slowest step involved in the biosorption process. The average effective diffusion coefficient was found to be 1.44 x 10(-9) cm(2)/s. Thermodynamic studies confirmed the biosorption process to be exothermic.

Novel approach towards recovery of glycosaminoglycans from tannery wastewater

Poly ethylene glycol (PEG)-poly acrylic acid (PAA) based aqueous two-phase system (ATPS) was selected as a practical model to recover glycosaminoglycans (GAGs) from tannery wastewater. The influence of PEG molecular weight, tie line length (TLL), pH, temperature and NaCl concentration on the partition coefficient of glycosaminoglycans from tannery wastewater was studied. Partition coefficient of glycosaminoglycan decreases on increase of PEG molecular weight, NaCl concentration and temperature, whereas it increases with increase of pH. In the PEG-rich phase, increased partitioning of GAGs was observed with increase in TLL. The partitioning of GAGs was better in PEG 4000 at pH 8.0, 20 °C with a yield of 91.50%. This study demonstrates the potential application of ATPS processes for the recovery of GAGs from complex biological suspensions.

Influence of PCL on the material properties of collagen based biocomposites and in vitro evaluation of drug release

Formulation of biodegradable collagen-poly-ε-caprolactone (PCL) based biomaterials for the sustained release of insulin is the main objective of the present work. PCL has been employed to modulate the physico-chemical behavior of collagen to control the drug release. Designed formulations were employed to statistically optimize insulin release parameter profile at different collagen to PCL molar ratios. Circular dichroism, thermoporometry, FTIR, impedance and scanning electron microscopy techniques have been employed to investigate the effect of PCL on hydration dynamics of the collagen molecule, which in turn changes the dissolution parameters of the drug from the systems. Drug entrapment efficiency has been found to be maximum for collagen to PCL molar ratio of 1:2 (>90%). In vitro dissolution test reveals that 99% of the drug was released from composite at collagen to PCL molar ratio of 1:3 and 1:4 within 2h, which indicates that hydrophobicity of the matrix results in weak interaction between lipophilic drug and carrier materials. The least burst release was observed for collagen to PCL molar ratio at 1:2 as synergistic interactions between collagen and PCL was maximum at that particular polymer-polymer ratios. The drug release data indicates super case-II transport of drug (n>1.0).

Rapid hydrogenation: perfect quasi architecture (Ag@SiO2NPs) as a substrate for nitrophenol reduction

Spherical nanoparticles with core-frame architecture are a viable route to combine multiple functionalities on a nanoscopic scale. Amongst these nanoparticles, metal polymeric hybrid nanostructures exhibit significantly enhanced stability. Synergistic catalytic responses arise from quasi perfect morphology and their unique interactions between the metal and reactant substrate. Core-frame silver supported silica nanoparticles (Ag@SiO2NPs) with different frame thicknesses were tailored in a controlled manner through an oversimplified environmentally friendly route using simple chemical additives instead of dendrimers as linkers for prior modification of AgNPs. Here the optical and thermal properties of Ag@SiO2NPs were studied by high resolution transmission electron microscopy (HRTEM), dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). The resulting stabilised nature of Ag@SiO2NPs, their functionalization and environmental behaviour were analysed in detail through absorbance measurements. The control over the particle geometry provided an opportunity to utilise this hybrid NP as a temper for faster hydrogenation of p-nitrophenol with minimal reductant concentration (3 mM NaBH4). The effect of the volume ratio of the hybrid catalyst with respect to thermal behaviour and their hydrogenation reaction time, average reaction rate and hybrid reusability were thoroughly investigated. The reported high performance towards faster hydrogenation was completed within 300 s at 25 °C and 16 s at 60 °C. The synergetic behaviour of core-frame morphology provides faster electron transfer for hydrogenation and enhanced thermal stability against poisonous environments.

Antibacterial activity of copper(II) complexes against Staphylococcus aureus

Biofilm formation on medical implants is very difficult to overcome, since the bacteria in this form resist the host defense mechanism and antibiotic therapy. What is needed is the development of an anti-biofouling agent which will prevent the formation of a biofilm especially on periprosthetic implants. In this study, the antibiofilm forming potential of two copper(II) complexes namely, [Cu(bitpy)(dmp)](NO3)2 (1) and [Cu(bitpy)2](ClO4)2 (2) was studied against Staphylococcus aureus MTCC – 7443, a soil isolate. From the preliminary investigations, it became clear that the anti-staphylococcal activity of complex 2 was better than complex 1 because of the damage the complex caused at the membrane level by inhibiting the expression of some extracellular proteins responsible for biofilm formation. Further, the antibiofilm forming nature of complex 2 was confirmed by biofilm susceptibility tests, SDS – PAGE and microscopic imaging techniques. Complex 2 can therefore be used as one of the antibiofilm forming agents to curb the formation of biofilms on medical implants.

Effect of UV irradiation on the physico-chemical properties of iron crosslinked collagen.

Collagen is the main component of connective tissue and finds immense applications as a biomaterial. In this study, effect of UV irradiation on collagen crosslinked with iron has been carried out. The physical and optical properties of crosslinked collagen affected by UV irradiation were analyzed using electrospectral and fluorescence studies. The electronic spectral studies showed that the photoproducts formed on UV radiation decrease in the presence of iron. Circular dichroic studies revealed that the conformational changes brought about in the protein due to UV irradiation have been reduced owing to the crosslinking with iron. However, prolonged irradiation does bring about conformational changes to the protein.

A microscopic evaluation of collagen-bilirubin interactions: in vitro surface phenomenon.

This study is carried out to understand the morphology variations of collagen I matrices influenced by bilirubin. The characteristics of bilirubin interaction with collagen ascertained using various techniques like XRD, CLSM, fluorescence, SEM and AFM. These techniques are used to understand the distribution, expression and colocalization patterns of collagen–bilirubin complexes. The present investigation mimic the in vivo mechanisms created during the disorder condition like jaundice. Fluorescence technique elucidates the crucial role played by bilirubin deposition and interaction during collagen organization. Influence of bilirubin during collagen fibrillogenesis and banding patterns are clearly visualize using SEM. As a result, collagen–bilirubin complex provides different reconstructed patterns because of the influence of bilirubin concentration. Selectivity, specificity and spatial organization of collagen–bilirubin are determined through AFM imaging. Consequently, it is observed that the morphology and quantity of the bilirubin binding to collagen varied by the concentrations and the adsorption rate in protein solutions. Microscopic studies of collagen–bilirubin interaction confirms that bilirubin influence the fibrillogenesis and alter the rate of collagen organization depending on the bilirubin concentration. This knowledge helps to develop a novel drug to inhibit the interface point of interaction between collagen and bilirubin.

Dielectric behavior of gelatine-glycosaminoglycans blends: an impedance analysis.

The dielectric behavior of the gelatine-GAGs based blend systems has been studied to understand the dynamic behavior of the water at the protein-GAGs interfaces which are relevant for tissue engineering application. Impedance (Z) and phase have been measured as a function of frequencies from 0.01 Hz to 100 kHz. GAGs tunes the ionic charge drift which initiates polarization mechanisms through charge accumulation at structural interfaces and creates conduction currents. The admittance results showed that at high frequency, the conductivity increases with increasing GAGs concentration indicating changes in hydration shell of the gelatine by the GAGs.

Development of smart leathers: incorporating scent through infusion of encapsulated lemongrass oil

Fragrant nanospheres were formed by an emulsion polymerization technique using chitosan and acrylic acid as a wall material. Several parameters such as the ratios of lemongrass oil : surfactant and chitosan : acrylic acid, and relative lemongrass oil content in the nanospheres were analysed. Subsequently, the physico-chemical characteristics of nanospheres were characterized using FT-IR, dynamic light scattering, and SEM. The results showed that nanospheres were formed using ratios of lemongrass oil : Triton X-100 at 1 : 1, and of chitosan : acrylic acid at 1 : 2. The nanospheres showed high oil loading (∼300%) and encapsulation efficiency (∼33%) and had an average size of 117 ± 11 nm. In addition to that, the antimicrobial activity of the nanospheres was tested against bacteria (Bacillus subtilis, Bacillus cereus) and fungi (Rhizoctonia solani, Macrophomina phaseolina, Aspergillus fumigatus). Further, the application of nanospheres loaded with lemongrass oil in leather processing was optimized (stage of addition and percentage offer). Physico-chemical characteristics such as physical strength, morphology, washability, perception evaluation, water diffusion and organoleptic properties were investigated. The results revealed that the nanospheres were embedded in the leather matrix and that their fragrance persisted after washing with water and solvent. These nanospheres act as good delivery vehicles for the manufacture of fragranced leather and will add economic value to the leather.

Molecular Understanding of Collagen Stabilization: Interaction of Valeraldehyde with Collagen

The present study explains the molecular level interaction of valeraldehyde with collagen. Valeraldehyde is a monoaldehyde, which involves crosslinking with protein through covalent linkages. The role of valeraldehyde as a crosslinking agent for collagen stabilization was studied. Molecular modeling approaches was used to understand the interaction of collagen like peptide with valeraldehyde, which mimic the aldehyde tanning processes involved in protein stabilization. Crosslinking efficiency of valeraldehyde was found to increase with an increase in concentration due to the higher availability of aldehydic groups involved in crosslinking with collagen. Valeraldehyde interacted collagen membrane showed an increase in thermal stability by 25°C at pH 8. In the presence of valeraldehyde, collagen fibrils nucleation center was shifted from a lower to a higher range. Shift in the nucleation center was observed in the reduction of gelling time. Water accessibility in valeraldehyde interacted collagen membrane was reduced due to a higher crosslinking rate in the collagen. Modified collagen membrane by valeraldehyde at incubation of about 96 h showed higher resistance to collagenolytic activity of 81%. The amino groups reacting appear to be involved in crosslinking with valeraldehyde. Several interaction sites were identified and the docking energy obtained was −5.539 kcal/mol. The participation of the aldehyde group with amino groups in collagen was observed, which plays a dominant role in the stabilization of peptide by valeraldehyde. It was found that complexes exhibit covalent bonding, hydrogen bonding and electrostatic interaction in the process of stabilization.