# Antibacterial Efficacy and Biocompatibility of Denim Fabrics Finished with Plant-Based Nanoemulsions Using Mechanical Finishing and Digital Printing

## TL;DR

This study shows that plant-based nanoemulsions can make denim fabrics antibacterial and durable, reducing the need for frequent washing and offering a sustainable alternative to synthetic treatments.

## Contribution

The first use of plant-based herbal nanoemulsions for durable antibacterial denim finishing via mechanical and digital methods.

## Key findings

- Karanja and Shankapushpi nanoemulsions showed >99.7% antibacterial efficacy against S. aureus and E. coli.
- Antibacterial properties remained >99.2% after washing, showing durability.
- Digital printing proved more efficient and resource-saving than mechanical finishing.

## Abstract

This research examines mechanical finishing and digital
printing
methods for imparting antibacterial properties to denim fabrics. It
evaluates the use of plant-based nanoemulsions, which are nontoxic
and environmentally friendly, as alternatives to synthetic antimicrobial
agents. This finishing technique enhances the functional properties
of denim fabrics, enabling them to be used for longer periods without
requiring frequent washing. Additionally, it prevents the formation
of odor and microbial growth during consumer use. Two types of nanoemulsions,
namely, Karanja and Shankapushpi, were derived from plant-based herbs
combined with coconut oil and curry leaves. The nanoemulsions were
characterized for their thermal stability, particle size, and percentage
add-on. The finished denim fabrics were assessed for their antimicrobial
properties using Gram-positive bacteria (Staphylococcus
aureus) and Gram-negative bacteria (Escherichia coli). Furthermore, the durability and
skin safety of the finished fabrics were tested. The antimicrobial
efficacy of Karanja nanoemulsion before washing was 99.73% (S. aureus) and 99.74% (E. coli), and for Shankapushpi, it was 99.77% (S. aureus) and 99.73% (E. coli). For digitally
printed denim, no increase in bacterial growth was observed after
24 h. After washing, only a marginal reduction in the antibacterial
efficacy (>99.2%) of the finished denim fabrics was observed, demonstrating
the durability of the finish. In vitro cytotoxicity assessments demonstrated
a cell viability of >70%, indicating acceptable cytotoxicity of
the
denim fabric and safety on the skin. Fourier transform infrared spectroscopy
(FT-IR) analysis revealed the presence of a triple-bond carbon at
2105 cm–1 and fatty acids at 3006 cm–1 in both the nanoemulsions, Karanja and Shankapushpi, which are responsible
for the antimicrobial property. This research suggests that denim
fabrics can be treated with durable antibacterial properties using
sustainable, environmentally friendly, and biocompatible plant-based
herbal nanoemulsions. The digital printing method that uses fewer
resources demonstrated high precision in applying the nanoemulsion
to the fabric and proved more efficient than mechanical methods. This
research introduces innovative approaches to enhance denim fabrics
by preventing unpleasant odors from microbial growth, disinfecting
surfaces, and reducing the frequency of washing. These methodologies
employ plant-based herbal treatments for the first time to enhance
denim functionality, highlighting potential applications in sportswear
and athleisure that prioritize freshness, durability, and sustainability.