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PD ISO TS 16550:2014 pdf free

PD ISO TS 16550:2014 pdf free.Nanotechnologies – Determination of silver nanoparticles potency by release of muramic acid from Staphylococcus aureus
PGN is a specific and essential component in the cell wall of bacteria.[8] Its main structural features are linear glycan strands cross-linked by short peptides. The glycan strands are made up of alternating N-acetylglucosamine and N-acetylmuramic acid, MA, residues linked by β-1- 4 bonds, and the peptide chain is composed of L-alanine, D-glutamine, L-lysine, and D-alanine in the case of S. aureus (see Figure 1 a).[8][2] It has been shown that AgNPs will damage the bacterial cell wall and production of the PGN fragments, leading to increased MA concentration in the culture media.[8][12]
AgNPs as the active entity of colloidal AgNPs could have various sizes, surface features, shapes, zeta potential, and concentrations in different trade products. The activity of AgNPs depends on the mentioned characteristics, which could have synergistic or antagonistic cross-effects.[2] Distinguishing among the effects caused by each of these parameters would require the preparation of a large number of samples and use of a great variety of instrumentations. Subsequently, monitoring the concentration of MA is one indicator of the effects of these characteristics on AgNPs potency.I12][13][14][15][16]
This Technical Specification utilizes a very sensitive measure of a single analyte, muramic acid as an indirect measure of a single mode of action, cell wall degradation. This method’s sensitivity allows for muramic acid quantification below the minimum inhibitory concentration (MIC).[17][18] However, the effect of silver nanoparticles detected through muramic acid liberation does not indicate lethality or cessation of cell growth.
Furthermore, the method relies on a single laboratory synthesized calibration sample to establish a dose response curve for later use with a widely accepted reference. Nanoparticles possess a particle-chemical duality; in that, the particle can be a reservoir for chemical release by dissolution processes.The protocol described in this Technical Specification does not offer information about broad spectrum bactericidal action of silver nanoparticles.
An effect on Staphylococcus aureus cannot be predictive for other Gram positive organisms and would not be expected to apply to Gram negative organisms due to the profound structural difference between the two cell wall types with respect to peptidoglycan proportion. Thus, this is not a comprehensive survey of nanoparticle effects upon bacteria.
In light of these considerations, characterization data for the laboratory-prepared silver nanoparticle calibration and system validation reference material can be found in Annex C.PD ISO TS 16550 pdf download.

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