Because
of the broad-spectrum antimicrobial efficacy, silver-based
coatings have emerged as the popular choice to apply over frequently
touched surfaces for mitigating the spread of nosocomial infections.
Despite the advancements through various coating strategies, clustering
of the active component remains a bottleneck in achieving the molecular-scale
dispersion of silver. To circumvent this, the current study takes
advantage of the recent findings of quaternary ammonium moieties forming
molecular complexes with silver salts that differ from the simple
adduct between the individual components. Here we demonstrate the
quaternization of oxidatively cross-linked polydopamine coatings over
magnetite nanoparticles to anchor ionic silver at a molecular-scale
dispersion. The silver-derivatized materials exhibit remarkable broad-spectrum
antimicrobial properties against representative microbes like E. coli, S. aureus, and A. niger. Also, the study reveals the materials’ antibiofilm efficacy
(∼80–90%) against both bacteria. Further recyclability
studies have proven the sustained bactericidal properties up to five
cycles. The surface derivatization strategy has then been extended
to cover glass slips that have also shown the retention of the bactericidal
properties even after wiping 20 times with artificial sweat. The biocompatibility
of the materials has been ascertained with treated water against the
mouse fibroblast and human embryonic kidney cell lines. The current
study offers insights in developing coatings with molecular-scale
dispersion of ionic silver to achieve broad-spectrum antimicrobial
properties in an atom-economical and sustainable manner.
BackgroundNon-invasive sampling has opened avenues for the genetic study of elusive species, which has contributed significantly to their conservation. Where field based identity of non-invasive sample is ambiguous (e.g. carnivore scats), it is essential to establish identity of the species through molecular approaches. A cost effective procedure to ascertain species identity is to use species specific primers (SSP) for PCR amplification and subsequent resolution through agarose gel electrophoresis. However, SSPs if ill designed can often cross amplify non-target sympatric species. Herein we report the problem of cross amplification with currently published SSPs, which have been used in several recent scientific articles on tigers (Panthera tigris) and leopards (Panthera pardus) in India. Since these papers form pioneering research on which future work will be based, an early rectification is required so as to not propagate this error further.ResultsWe conclusively show cross amplification of three of the four SSPs, in sympatric non-target species like tiger SSP amplifying leopard and striped hyena (Hyaena hyaena), and leopard SSP amplifying tiger, lion (Panthera leo persica) and clouded leopard (Neofelis nebulosa), with the same product size. We develop and test a non-cross-amplifying leopard specific primer pair within the mitochondrial cytochrome b region. We also standardize a duplex PCR method to screen tiger and leopard samples simultaneously in one PCR reaction to reduce cost and time.ConclusionsThese findings suggest the importance of an often overlooked preliminary protocol of conclusive identification of species from non-invasive samples. The cross amplification of published primers in conspecifics suggests the need to revisit inferences drawn by earlier work.Electronic supplementary materialThe online version of this article (doi:10.1186/s12863-016-0344-y) contains supplementary material, which is available to authorized users.
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