Electrodeposited functionally graded coating inhibits Gram-positive and Gram-negative bacteria by a lipid peroxidation mediated membrane damage mechanism

Mater Sci Eng C Mater Biol Appl. 2019 Sep:102:623-633. doi: 10.1016/j.msec.2019.04.087. Epub 2019 Apr 29.

Abstract

The current work deals with a time-dependent study to track the antibacterial action of electrodeposited Cu, Cu-SiC functionally graded coating (FGC) against Escherichia coli NCIM 2931 (Gram-negative) and Bacillus subtilis NCIM 2063 (Gram-positive). After 24 h of incubation, the Cu, Cu-SiC FGC causes 7 Escherichia coli NCIM 2931 and 10 Bacillus subtilis NCIM 2063 log reduction of planktonic cells. The outer membrane permeabilization experiment proves that the intake of excessive Cu ions leads to the damage of bacterial cell membrane followed by lipid degradation. The thiobarbituric acid reactive substances assay reveals that Cu ions released from the surface of Cu, Cu-SiC FGC triggers the oxidative degeneration of phospholipids (most abundant constituent of bacterial cell membrane). This was further cross-verified using atomic absorption spectroscopy. From 0 to 24 h, the bacterial morphology is characterized using transmission electron microscope and scanning electron microscope which shows the cytoplasmic leakage and cell death. The Cu, Cu-SiC FGC also exhibits hydrophobic surface (contact angle of 144°) which prevents the bacterial adherence to the surface and thus, inhibits them to penetrate into its bulk. The observed results of antibacterial and anti-adhesion properties of Cu, Cu-SiC FGC are compared with single-layered metallic Cu and Cu-SiC nanocomposite coatings. Hence, the electrodeposited Cu, Cu-SiC FGC has the potential to serve as an inexpensive touch surface alternative for the healthcare industries.

Keywords: Anti-adhesion; Antibacterial; Functionally graded coating; SiC nanoparticle; Surface roughness; Wettability.

MeSH terms

  • Anti-Bacterial Agents / pharmacology
  • Bacillus subtilis / drug effects
  • Bacillus subtilis / growth & development
  • Bacillus subtilis / ultrastructure
  • Bacterial Adhesion / drug effects
  • Cell Membrane / drug effects
  • Cell Membrane / metabolism*
  • Coated Materials, Biocompatible / pharmacology*
  • Colony Count, Microbial
  • Copper / metabolism
  • Electroplating / methods*
  • Escherichia coli / drug effects
  • Escherichia coli / growth & development
  • Escherichia coli / ultrastructure
  • Gram-Negative Bacteria / drug effects*
  • Gram-Positive Bacteria / drug effects*
  • Ions
  • Lipid Peroxidation / drug effects*
  • Microbial Sensitivity Tests
  • Microbial Viability / drug effects
  • Thiobarbituric Acid Reactive Substances / metabolism
  • Time Factors

Substances

  • Anti-Bacterial Agents
  • Coated Materials, Biocompatible
  • Ions
  • Thiobarbituric Acid Reactive Substances
  • Copper