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This current study is aimed towards the fabrication of AZ31 magnesium cylindrical mesh cage implant with circular holes for orthopedic applications. This mesh cage is coated with nanocomposite material containing polycaprolactone (PCL), pluronic F127 and nano hydroxyapatite (nHA) by electrospinning process. Morphology and composition were analyzed by various characterization techniques. Controlled degradation and weight loss of the nanocomposite coated samples in 28 days were observed when compared with uncoated samples in SBF (simulated body fluid). The nanocomposite coated material was not cytotoxic to MG63 osteosarcoma cells. The cell viability, morphology, ALP activity, calcium mineralization and collagen deposition were also better on this when compared to uncoated. Smooth and randomly deposited nanofibers on the mesh cage was observed and the contact angle indicated that the surface is hydrophilic with (initial contact angle of 55 ± 1° and after 10 s 0°) when compared to PCL (99°) coated surface. 2-5 fold higher mRNA expression levels of osteogenic genes namely ALP, BMP2, COL1 and RUNX2 was observed with nanocomposite coated scaffolds than uncoated and PCL coated samples in 14 days. These results indicate the potential use of the nanocomposite coated AZ31 cylindrical mesh cage for segmental bone defect repair and can be used as a degradable implant for orthopedic applications., (Copyright © 2018. Published by Elsevier B.V.)

Papain is covalently crosslinked on polycaprolactam and tested as a wrapper for packaging cottage cheese, against E. coli biofilm. The bacterial count on neat polycaprolactam (NP) was 50×10(6)/ml on the 5th day which dramatically increased to 300×10(6) colony forming units (CFU)/ml by the end of 30th day. The corresponding CFU/ml on papain functionalized polycaprolactam (FP) was 10×10(2) on 5th day and 20×10(2) by the end of 30th day. Fourier transform infrared spectroscopic (FTIR) analysis of biofilm on NP showed the presence of polysaccharide, protein, lipid and metabolites which was three times reduced on FP. FT Raman spectroscopy showed the effect of papain on functional groups such as hydroxyl, amino, carbonyl, phosphoryl and aliphatic, leading to the inhibition of the biofilm. Motility, hydrophobicity and zeta potential of E. coli on NP and FP were 10.67 and 5.65 μm/s/V/cm; 88 and 20%; 8.93±2.09 and 2.65±0.52 mV respectively, thereby decreasing the biofilm forming ability of E. coli., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Myriad applications of surfactin in environmental and biomedical field prompt understanding the self-assembly behaviour of surfactin in aqueous solution as well as its interaction with counterions. Effect of four divalent counterions namely, Ni(2+), Zn(2+), Cd(2+), and Ca(2+) on the self-assembly of the surfactin, a biosurfactant isolated from Bacillus subtilis YB7 is studied by fluorescence spectroscopy, dynamic light scattering, optical and electron microscopic studies. The critical micelle concentration (CMC) and aggregation number (Nagg) of surfactin are 96.76 ± 15.49 μM and 101.12 ± 2.53, respectively. The degree of counterion association increases as its ionic radius decreases. Ni(2+) exhibits the highest and Ca(2+) the least degree of counterion association. Addition of counterion reduces the size of the microstructures, aggregation number (Nagg) and zeta potential. The reduction in the zeta potential indicates the neutralization of the negative charges on the electrical double layer of the microstructures. Differential interference contrast (DIC) and transmission electron microscopic (TEM) images of surfactin show the presence of vesicles and large aggregates including giant vesicles. On the addition of Ca(2+), fusion of vesicles into large aggregates is predominantly observed. Ni(2+) induces the transition of large spherical vesicles into small spherical, worm-like vesicles and multicompartment-like structures (vesosome). Such structures are the evidences for metal ion coordinated intervesicular interactions. This study reveals that the self-assembly process of surfactin can be controlled by the addition of metal ions according to the requirements., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Nitrated and aminated polycarbonates were prepared chemically, characterized and tested in vitro as a possible biomaterial. Adhesion of Staphylococcus aureus NCIM 5021, Escherichia coli NCIM 2931 and Proteus vulgaris NCIM 2813 and the presence of carbohydrate, protein, CFU and ATP on these surfaces were examined. Cytotoxicity of these surfaces was investigated by growing L929 mouse fibroblast cells. NO2-PC was more hydrophilic than un-PC and reduced adhesion of bacterial protein and carbohydrate. NH2-PC was the most hydrophilic surface biofilm prevention and increased proliferation of the fibroblast cells. The motility of all the three organisms decreased on aminated surface when compared to that on the other two. This study indicated that reducing the surface hydrophobicity alone was not sufficient to develop a biocompatible material, but providing favorable surface functional groups was also a necessary criterion. A strong correlation was observed between the hydrophobicity of the polymer surface and the zeta potential of the organism with bacterial attachment (CFU/ml). A multi-linear regression model with these two parameters was able to fit the observed bacterial attachment data well., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Biofouling on six different (silicone rubber, polydimethylsiloxane, polypropylene, high density polyethylene, polyvinylchloride, and polycarbonate) substrata with varying surface energy (18-40 mN/m) and surface roughness (R(a) 45-175 μm) was studied in the Eastern coastal waters of India over a short period of time (3 days). The results showed that the substrata surface energy (SE) followed by the surface roughness (R(a)) had profound effect on attachment of fouling organisms. After one day of immersion, viable count of bacteria in the biofilm was positively correlated with surface energy (r=0.69, p<0.05) and not with surface roughness (r=-0.02) of the substratum. Whereas, Pseudomonas count was inversely correlated with surface energy (r=-0.66, p<0.05) and surface roughness (r=-0.52, p<0.05). The attachment of macrofouler and the surface characteristics were also well correlated with SE 0.48 and with roughness 0.62, p<0.05. A positive correlation was observed amongst the various biofouling constituents such as bacteria, ATP, carbohydrates and organic matter on almost all the substrata. However after the first day, the surface characteristics of the substratum became less important and the conditioning film that was formed on the substrata appeared to directly influence further fouling on the surfaces, as evidenced by poor correlation between surface energy and macrofouler attachment (r=-0.11). The observation of high numbers of Hydroides elegans on PVC could be solely due to the influence of surface roughness (r=0.62). Though there is no marked difference in the 'primary film', and the composition of the biofilm, the amount of attached macrofouler is minimal on silicone rubber and polydimethylsiloxane on subsequent days of immersion, which reveals the foul release quality of these substrata probably due to their flexible nature., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Biocompatibility of medical grade polyurethane coated with polyaniline (PANi) and polyaniline-silver nanoparticle composite (PANi-AgNp) is reported here. These modified films showed 23 and 18% of 3T3 L1 cell death when compared to 41% with virgin polyurethane (PU) after 48h of incubation, respectively. All the surfaces elucidated inflammatory response in the form of enhanced expressions of the proinflammatory cytokines genes, TNF-α and IL-6. But these values were less (by 20%) on modified films than on the bare PU. Attachment of Pseudomonas and Bacillus were markedly less on PANi-AgNp coated surface (by 90.6 and 50.5%, respectively) when compared to the uncoated PU. As the CFU counts decreases on the nanoparticle coated PU, the adsorbed carbohydrate as well as protein content on to the surface of polymer decreases accordingly, indicating less attachment. A 20% reduction in the thickness of biofilm was observed in PANi-AgNp coated PU surface. A very strong positive correlation is observed between the contact angles of the polymers and the various biological parameters (namely colony forming units, protein, carbohydrate, cell death and inflammatory response), indicating hydrophilic surfaces prevent bacterial biofilm as well as are compatible to cells when compared to hydrophobic surfaces. Coating PU with PANi and PANi+AgNp renders the surface conductive, suggesting potential application in electrochemical biosensors. In addition, these modifications make the surface more biocompatible than the original PU., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Marine paint mixed with 2-methoxy-2',4'-dichloro chalcone is able to considerably reduce the formation of biofilm by Vibrio natriegens, a marine bacterium, on polycarbonate (PC), polymethylmethacrylate (PMMA) and glass fiber reinforced plastic (GFRP). These polymers have been selected for the study, since they have wide marine applications. Surfaces coated with dichloro chalcone containing marine paint had the lowest number of colony forming units (CFU) (1-5×10(6)), proteins (20-30 μg/cm2) and carbohydrates (5-10 μg/cm2) attached to them after 28 days of exposure to the organism when compared to surfaces coated with CuSO4 mixed paint (20-40×10(6) CFU/ml, proteins of 50-60 μg/cm2 and carbohydrates of 40-50 μg/cm2) or plain marine paint (30-40×10(6) CFU/ml, proteins of 120-150 μg/cm2 and carbohydrates of 40-60 μg/cm2). At the end of the study period, the biofilm on PMMA was 7, 10 and 12 μm thick on chalcone, copper and plain paint coated surfaces, respectively. The first two paints increased the surface roughness but decreased the surface hydrophobicity when compared to the plain paint. Large number of dead cells was found on the chalcone mixed and predominantly live cells were found on plain paint coated surfaces. 15% of dichloro chalcone had leached out of PMMA surface after 28 days. The low amount of biofilm formed in the presence of dichlorochalcone can be associated to its antibacterial and slimicidal activity and also its ability to reduce the hydrophobicity of the surface. This dichlorochalcone appears to be a novel agent for decreasing the formation of marine biofilm., (Copyright © 2010 Elsevier B.V. All rights reserved.)

Localized corrosion of stainless steel beneath the barnacle-base is an unsolved issue for the marine industry. In this work, we clearly bring out for the first time the role of the barnacle cement in acting as an etchant, preferentially etching the grain boundaries, and initiating the corrosion process in stainless steel 316L. The investigations include structural characterization of the cement and corroded region, and also chemical characterization of the corrosion products generated beneath the barnacle-base. Structural characterization studies using scanning electron microscopy (SEM) reveals the morphological changes in the cement structure across the interface of the base-plate and the substrate, modification of the steel surface by the cement and the corrosion pattern beneath the barnacle-base. Fourier transform infrared spectroscopy (FTIR) of the corrosion products show that they are composed of mainly oxides of iron thereby implying that the corrosion is aerobic in nature. A model for the etching and corrosion mechanism is proposed based on our observations., (Copyright © 2010 Elsevier B.V. All rights reserved.)

Localized corrosion of stainless steel beneath the barnacle-base is an unsolved issue for the marine industry. In this work, we clearly bring out for the first time the role of the barnacle cement in acting as an etchant, preferentially etching the grain boundaries, and initiating the corrosion process in stainless steel 316L. The investigations include structural characterization of the cement and corroded region, and also chemical characterization of the corrosion products generated beneath the barnacle-base. Structural characterization studies using scanning electron microscopy (SEM) reveals the morphological changes in the cement structure across the interface of the base-plate and the substrate, modification of the steel surface by the cement and the corrosion pattern beneath the barnacle-base. Fourier transform infrared spectroscopy (FTIR) of the corrosion products show that they are composed of mainly oxides of iron thereby implying that the corrosion is aerobic in nature. A model for the etching and corrosion mechanism is proposed based on our observations.