# Exploiting Greener Formulations of Benzalkonium Chloride with Enhanced Antibacterial Properties

## TL;DR

This paper presents a greener disinfectant formulation using nanodroplets to reduce the toxicity and environmental impact of benzalkonium chloride.

## Contribution

A novel green spray disinfectant formulation using nanodroplets to reduce BKC concentration and enhance antimicrobial activity.

## Key findings

- BKC-NDs showed superior antimicrobial activity against S. aureus and E. coli compared to BKC in solution.
- The 0.08% w/v BKC-NDs formulation maintained in vitro biocompatibility and high antimicrobial efficacy.
- BKC-NDs demonstrated good physicochemical properties like wettability, spray angle, and long-term stability.

## Abstract

In recent years, the extensive use of benzalkonium chloride
(BKC)
as a disinfectant has raised significant concerns due to its toxicity
and its potential to promote environmental impact and antimicrobial
resistance. In order to reduce the toxicity associated with BKC in
spray disinfectants, the antimicrobial agent was coencapsulated into
vesicle-like nanosystems, known as nanodroplets (NDs), with limonene,
a natural essential oil renowned for its antimicrobial properties
and commonly used in cleaning product formulations. The aim was to
reduce the required concentration of BKC in the disinfectant formulation
by enhancing its antimicrobial activity through encapsulation in nanodroplets
(BKC-NDs) and by loading limonene within the core of the nanodroplets. The vesicles consist of two distinct phases:
an organic core composed of decafluoropentane and
limonene and an outer aqueous shell stabilized at the interface by
BKC. In this formulation, therefore, BKC plays both a functional role
as an antimicrobial agent and a technological role as a surfactant,
allowing for the formation of the NDs. Moreover, a more sustainable
formulation was obtained by removing decafluoropentane and retaining
limonene in the vesicle core. A library of BKC-NDs
with varying BKC concentrations (0.008, 0.08, and 2.4% w/v), with
or without a decafluoropentane core, was prepared
to finally select the minimum concentration with the highest antimicrobial
activity. BKC-NDs demonstrated superior antimicrobial properties compared
to BKC in aqueous solution against Staphylococcus aureus and Escherichia coli and, in particular,
the formulation at 0.08% w/v, while maintaining comparable in vitro biocompatibility. The efficiency of BKC-NDs spray
disinfectants was also assessed from a physicochemical perspective,
demonstrating high wettability, wide spray angle, and long-term stability
upon storage while retaining antimicrobial efficacy. A novel green
spray disinfectant based on BKC, which exploits materials of natural
origin to reduce the concentration of chemicals, was developed to
minimize its related toxicity and environmental contamination.