Microbial infections are significant threats to human health [1], [2]. Biofilm formation is associated with over 80% of microbial infections [3]. Staphylococcus aureus and Candida albicans are widely recognized as the predominant human pathogens, capable of causing a range of infections from superficial to invasive, with potentially severe consequences for human health. These infections can lead to considerable mortality and morbidity [4]. The formation of S. aureus and C. albicans biofilms are a complex phenomenon that can be categorized into four primary stages: initial attachment, production of extracellular matrix, biofilm proliferation, and recolonization (Fig. 1A) [5].

Polymicrobial biofilms are responsible for a multitude of infections in developed nations, encompassing conditions such as osteomyelitis, cystic fibrosis, and various nosocomial infections. (Fig. 1B) [6]. The ability of pathogens to form biofilms is a significant factor in the development of antibiotic drug resistance, causing a global public health threat [7]. Currently, pathogenic microbial biofilms are becoming tolerant to antibiotics and natural compounds, such as peptides, lipids, and other endogenous metabolites, which are effective against planktonic counterparts [2], [8], [9]. The biofilm tolerance can be attributed to several mechanisms, such as retarded diffusion, inactivation of antibiotics, metabolic dormancy, and persister cells [9], [10]. Thus, eradicating biofilm-associated infections is a serious challenge and pressing task.

Currently, researchers have been focusing on a new method that can effectively deliver antibiotic compounds to the biofilm interior to improve their antibiofilm efficacy [11]. Drug delivery carriers, such as liposomes, dendrimers, and niosomes, are frequently considered for the formulation and delivery of natural components and antibiotics for various treatments [12], [13], [14]. Unlike dendrimers and niosomes, liposomes can be loaded with hydrophobic and hydrophilic bioactive compounds [15]. Furthermore, it is worth noting that the Food and Drug Administration and the European Medicines Agency have granted approval to a number of medications that utilize liposome-based technology [16].

Liposomes are circular vesicles comprised of phospholipid bilayers that encapsulate an aqueous phase within their core [17], [18]. Liposomes demonstrate favorable biological attributes due to their similarity to biological membranes and possession of distinctive characteristics such as low toxicity, biocompatibility, and biodegradability [15], [19], [20], [21]. Owing to their biphasic nature, these can be used to deliver hydrophilic and lipophilic compounds [22]. Liposomes have the potential to enhance encapsulation efficiency through the improvement of drug solubility, enhancement of stability, and active delivery of loaded pharmaceuticals to specific bio-targets [12], [23].

So far, several liposomes have been prepared using various bio-active compounds, such as peptides [24], proteins [25], and immunoglobulin [26], but those for the encapsulation of fatty acids with enhanced antibacterial and antibiofilm are still challenging. There has been an increasing interest in investigating the antibacterial effects of elevated concentrations of fatty acids in recent times. Multiple recent studies have highlighted that certain fatty acids, even at sub-inhibitory concentrations, demonstrate significant antibiofilm and anti-virulence activities [27], [28], [29]. Many fatty acids, including LA and MA, were documented to demonstrate antibiofilm properties against S. aureus at low concentrations. Kim et al. [30] reported that LA at low concentrations (10 µg/mL) exhibited significant biofilm inhibitory properties against C. albicans.

From this significance, the present study aimed to formulate liposomes using soy lecithin and fatty acids using an emulsification method for enhanced antibiofilm activity (Fig. 1C). To the best of the authors’ knowledge, this is the first report on the synthesis of liposomes using LA and soy lecithin for enhanced biofilm inhibition activity against S. aureus and C. albicans and their dual biofilms. Five different ratios of liposome formulations were initially prepared using soy lecithin and different concentrations of LA, and the most potent formulation was investigated further. The physio-chemical properties of the liposomes were characterized using a zeta sizer, Fourier transform infrared spectroscopy, transmission electron microscopy, and nuclear magnetic resonance (NMR) spectroscopy. Further, biofilm assay was carried out to examine the antibiofilm potencies of liposomes against S. aureus and C. albicans or their dual biofilms. Furthermore, conventional microscopy and scanning electron microscopy were used to observe the variations in biofilm formation. In addition, the changes in the cell surface charge were analyzed using zeta potential analysis.