Preparation of antimicrobial/ultraviolet protective bacterial nanocellulose film with carbon dots synthesized from lactic acid bacteria

Int J Biol Macromol. 2020 Jul 15:155:216-225. doi: 10.1016/j.ijbiomac.2020.03.230. Epub 2020 Mar 30.

Abstract

Microbial biomass, as an environmentally friendly resource, has drawn a lot of attention as green biomaterials for production of unique and functionalized carbon dots (CDs). However, the hydrophilicity and high porosity drive bacterial nanocellulose as a suitable matrix for CDs with antimicrobial, photoluminescent and ultraviolet blocking features. For the first time, antimicrobial CDs were synthesized by hydrothermal method from cell-free supernatant of Lactobacillus acidophilus and characterized. Antimicrobial performance of CDs was examined on Escherichia coli (Gram-negative) and Listeria monocytogenes (Gram-positive). Additionally, the as-prepared CDs embedded by ex-situ method into nanocellulose in order to fabricate antimicrobial/ultraviolet protective nanopaper. The photoluminescent CDs with an average size of 2.8 nm and high-hydroxylated groups were synthesized. The CDs at 500 mg mL-1 concentration had antibacterial activity towards both bacteria. Moreover, nanopaper displayed a fluorescence appearance under ultraviolet. Nanocellulose with CDs loading capacity of 71.74 ± 4.13 mg cm-2 represented an appropriate stretchability and flexibility in comparison to nanocellulose. The CDs incorporated nanopaper also depicted greater ultraviolet-blocking specifications and inhibitory activity on Gram-positive bacterium than Gram-negative one. CDs can be used as a novel fluorescence antimicrobial/ultraviolet protective material in the nanocellulose film in order to develop an antimicrobial and forgery-proof packaging due to their fluorescence appearance.

Keywords: Active packaging; Antimicrobial film; Antioxidant; Lactobacillus; Probiotic; UV protective.

MeSH terms

  • Anti-Infective Agents / chemistry
  • Anti-Infective Agents / pharmacology*
  • Biomass
  • Carbon / chemistry*
  • Carbon / metabolism
  • Cellulose / chemistry*
  • Escherichia coli / drug effects*
  • Fluorescence
  • Hydrophobic and Hydrophilic Interactions
  • Lactobacillales / chemistry*
  • Lactobacillales / growth & development
  • Lactobacillales / metabolism
  • Listeria monocytogenes / drug effects*
  • Nanoparticles / chemistry

Substances

  • Anti-Infective Agents
  • Carbon
  • Cellulose