1. Vanadium pentoxide nanoparticles mimicvanadium haloperoxidases and thwartbiofilm formationV2O5 NWMetalLayerBacterial Attack HOBr Production Anti-fouling ActivityNoBiofilmformationPresented By:Madhulika SinhaGreen Chemistry ReportDept. Of ChemistryNational Tsing Hua University
2. History Introduction Synthesis and Activities Result & Discussion Conclusion Why I chose this paper? ReferencesNATURE NANOTECHNOLOGY | VOL 7 | AUGUST 2012 530 |2013.05.06
3. 2013.05.06 3NATURE NANOTECHNOLOGY | VOL 7 | AUGUST 2012 530 |“And arsenic and sulphur have been well mixed with Chian oiland the mixture evenly applied to the vessel’s sides that shemay speed through the blue waters freely and withoutimpediment.”-Translation from the Aramaic of papyrus dated 412BC“All ships’ bottoms were covered with a mixture of tallow andpitch in the hope of discouraging barnacles and teredo andevery few months a vessel had to be hove-down and graved onsome convenient beach”-Christopher ColumbusWorldwide problem in marine systems, costing US Navy alone anestimated $1 billion per annum (2002).Fouling leads to hull roughness & hydrodynamic drag; more energyrequired to propel the vessel through water; increased fuelconsumption & Green house gas emission4.Tributyltin-free and Silicon elastomers A/F coatings– Not suitableresults(1-4).“fleet generatesemissionsequivalent tonearly 190 millioncars–or all of thevehicles in the U.S”Marine biofouling- Small marine microorganisms Colonization,adhesion of barnacles, macroalgae and microbial slimes4.
4. 4NATURE NANOTECHNOLOGY | VOL 7 | AUGUST 2012 530 |2013.05.06INTRODUCTION−V2O5 NWt = 0−V2O5 NWt = 60 daysProduction of functional recombinant V-HPOs5 & isolation of naturally occurring V-HPOs6done- withstands organic solvents, but commercial production expensive7.a)Vanadium bound to Schiff base complexes8Functional inorg. V-HPO’s developedb) Peroxovanadium complexes9Advantages- efficient, selective in various oxidation states8Disadvantage- low stability and solubility, optimal working conditions (ex: organic solvents,extremely low pH) [8-10]Other Antibacterial NP’s like Ag, Cu, ZnO, Fe2O3 are either expensive or toxic to marine biota.Wolfgang et al
5. NATURE NANOTECHNOLOGY | VOL 7 | AUGUST 2012 530 |2013.05.065Vanadium Pentoxide Nano Wires(V2O5 NW) mimic naturally occurring VanadiumHalo peroxidase (V-HPO) enzyme, prevents bio film formation. V2O5 wires inpresence of Br-, Cl- etc. and H2O2 (both present in sea water) behaves like V-HPO’sand damage the ―quorum sensing of bacteria, without being toxic to the othermarine biota.H2O2 + X- + H+ = HOX + H2OH2O2 + Br- + H+ = HOBr + H2O(oxidant) (hypobromous acid)Singlet molecular oxygen (1O2) formed. Exerts strong antibacterial activity.Adv. Funct. Mater. 21, 501–509 (2011)INTRODUCTION Contd.Wolfgang et al(hypohalous acid)(oxidant)
6. NATURE NANOTECHNOLOGY | VOL 7 | AUGUST 2012 530 |2013.05.066Wolfgang et alVanadium Pentoxide NanoWires(V2O5 NW)50 nmSynthesis of V2O5 NW & Bromination activityFig. 1 | TEM image of V2O5 nanowiresSynthesis of V2O5 NW-VOSO4 + KBrO3 stirring for 30 min(@ RT)180 C/24 h. Reaction cooled @ RT dark-yellow precipitate(ppt.) dried @ 80 C overnight.Observation: Linear dependence of the rate of2-monochlorodimedone (MCD) brominationwith V2O5 NW concentration (Fig. 2 b).Fourfold difference in activity of the nanoscaleand bulk V2O5, indicates that the higher surfacearea of the nanostructured material is requiredto achieve higher catalytic efficiency.Chem. Rev. 104, (2004) & J. Am. Chem. Soc. 105, (1983)Fig. 2. Concentration dependence of their bromination activity
7. NATURE NANOTECHNOLOGY | VOL 7 | AUGUST 2012 530 |2013.05.067Wolfgang et alV2O5 NW activity at different parametersFig. 3 | Steady-state kinetics of the V2O5 nanowires at pH 8.3.3.(a) At higher concentrations of Br-, non-competitive inhibitory effect observed as inVanadium chloroperoxidase (V-CPO) [13-15]. Such inhibition is unexpected for inorg. NP’s.3.(b) Variation of H2O2 concentration, V2O5 nanowires, Br- and MCD Conc. constant.Michaelis– Menten behaviour observed. Steady-state kinetics determined in phosphatebuffer (pH 8.0), inhibition effect did not occur, suggests that buffer plays an important rolein catalysis. Values observed are similar to [ref. 16,17]V2O5 NW tolerate higher H2O2 conc., without reduction in their catalytic activity
8. NATURE NANOTECHNOLOGY | VOL 7 | AUGUST 2012 530 |2013.05.068Wolfgang et al3(c) Determine pH dependencebromination reaction rate catalyzed byV2O5 NW using diff. buffer, constantreactant conc.Buffer influences the stability of Peroxocomplex formed in initial stage ofreaction.V2O5 NW activity at different parameters3(d), Stability of catalytic activity ofV2O5 NW over a long period.No change in surface morphology wasobserved.
9. NATURE NANOTECHNOLOGY | VOL 7 | AUGUST 2012 530 |2013.05.069Wolfgang et alFig. 3(e) Proposed catalytic bromination mechanismfor the V2O5 nanowiresA mechanistic proposal for thebromination activity of V2O5 in thepresence of Br- and H2O2 based on thecrystal structure of V2O5 and thekinetic parameters.Figure S2 | 1O2 formation by V2O5 nanowirescatalyzing the oxidation of bromide by H2O2.The chemiluminescence derived fromthe singlet oxygen (1O2,1Δg) transition tostable triplet (1O2, 3Σg) was measured.A clear increase during the first 30 s isobserved reaching its maximum at 75sand dropping afterwards due to H2O2consumption.Bromination Mechanism
10. NATURE NANOTECHNOLOGY | VOL 7 | AUGUST 2012 530 |2013.05.0610Wolfgang et ala) Pure medium.b) Medium to which H2O2 (10 μM) andBr- (1mM) were added. No significantcolor changes occur.c) Medium to which V2O5 nanowires(0.02m/mL), H2O2 (10 μM) and Br-(1mM) were added.Observation:A significant color change from red topurple observed due to the V2O5mediated formation of HOBr thatdiffuses and reacts strongly with phenolred converting it to bromophenol.This data confirms that the V2O5nanowires, in the presence of H2O2 andBr-, display an intrinsic brominatingactivity.Figure S5 | Bromination of phenol redcontained in the Mannitol Salt Phenol RedAgar (S. aureus growth medium) by V2O5nanowires after 8h incubation at 37 C.Bromination of the MR Agar
11. NATURE NANOTECHNOLOGY | VOL 7 | AUGUST 2012 530 |2013.05.0611Wolfgang et alV2O5 nanowires display bromination activity in seawaterAcute toxicity (24 h LD50, dose lethal to 50% of animals tested) assessed by differentconcentrations of V2O5 nanowires on a marine biota model.In parallel, acute toxicity of different concentrations of International Maritime Organization(IMO)- approved compounds (Zn and Cu pyrithiones—Zn/CuPT) were also determined .Result : From dose–response curves, in terms of marine biota toxicity, V2O5 nanowires are 14and 1,000-fold less toxic than ZnPT and CuPT, respectively.Toxicity against Marine biotaFigure S7 | Bioassays/acute toxicity (24h LD50). The dose response curve was build for: a) CuPT, b) ZnPT andc) V2O5 nanowires.
12. NATURE NANOTECHNOLOGY | VOL 7 | AUGUST 2012 530 |2013.05.0612Wolfgang et alBacterial cell density/adhesion evaluated by fluorescence microscopy onthe different halves of painted stainless steel plates.No significant decrease of bacterial cells adhesion is observed indicatingthat the V2O5 nanowires are not toxic per se and is active only thepresence of the correspondent substrates (Br- and H2O2). Scale bar: 100μm.Fig. 5 | Potential biotechnological application of V2O5 nanowires as additive for marine paints withantibacterial/antifouling properties.−V2O5 NW+V2O5 NW +V2O5 NW−V2O5 NW −V2O5 NW +V2O5 NWPaintedstainlesssteelE. coli S. aureusa b cRESULT & DISCUSSION
13. NATURE NANOTECHNOLOGY | VOL 7 | AUGUST 2012 530 |2013.05.0613Wolfgang et alS. aureusS. aureus+V2O5NW +Br−+H2O2E. coli+V2O5NW +Br−+H2O2E. coliFig. 4 | Representative digital images showing the influence of the catalytic activity of V2O5 nanowireson the growth of Gram-positive (S. aureus) and Gram-negative (E. coli) bacteria.a b c dRESULT & DISCUSSION4(b) Gram-negative: E. coli co-incubated with V2O5 nanowires, Br- and H2O2.Decrease in bacterial population observed.4(d) Gram-positive: S. aureus co-incubated with V2O5 nanowires, Br- and H2O2.Color change from red to yellow indicates presence and growth of S. aureus.Comparatively, decrease in the bacterial population (90%) observed in 4(d).
14. NATURE NANOTECHNOLOGY | VOL 7 | AUGUST 2012 530 |2013.05.0614Wolfgang et al+V2O5 NW +V2O5 NWt = 0 t = 60 daysFig. 6 | Effect of nanoparticles on biofouling in situ.6(a-b) | Immediately after fixation, both stainless-steel plates (with and withoutV2O5 nanowires) had clean surfaces. The boat was kept in seawater (lagoon withtidal water directly connected to the Atlantic Ocean). After 60 days, the boat wastaken from the water. The painted stainless-steel plates with no V2O5 nanowiressuffered from severe natural biofouling and covered with Algae. Plates with V2O5nanowires showed a complete absence of biofouling.Result For Real Time Experiments
15. NATURE NANOTECHNOLOGY | VOL 7 | AUGUST 2012 530 |2013.05.0615Wolfgang et alCONCLUSIONVanadium pentoxide nanowires have the potential to be analternative approach to conventional anti-biofouling agents.
16. Nanotechnology- One of the most explored fields of Chemistry-Physics in the recent past (Thanks to Faraday’s colloidal Goldsuspension), must be taken into consideration for it’s possible uses inGreen chemistry and Technology. Many scientists and researchers are using Nanomaterials over bulkmaterials for Catalysis and other metal-catalyzed reactions. Nanomaterials have opened a new dimension of green chemistryby bringing down the consumption of chemicals to nano metrics. This paper displays one of the most important principle of GreenChemistry “Atom Economy”. Hence, I conclude, “SIZE DOES MATTERS”!16NATURE NANOTECHNOLOGY | VOL 7 | AUGUST 2012 530 |2013.05.06Wolfgang et al