Helicobacter pylori (H. pylori) is a widely spread pathogen that infects more than half of the world's population [1]. H. pylori infection can cause chronic gastritis, peptic ulcer disease (PUD), mucosa-associated lymphoid tissue (MALT) lymphoma and gastric cancer [2]. H. pylori infection initiates a progressive cascade of gastric mucosal damage, beginning with superficial colonization and potentially culminating in gastric adenocarcinoma. The disease evolves through distinct histopathological stages such as mucus layer infection, surface epithelial cell infection with vacuolar degeneration and proliferation, lamina propria inflammation, ulceration, and lymphoid hyperplasia, mucosal atrophy with gland loss, intestinal metaplasia, and smooth muscle proliferation, and intraepithelial neoplasia (low- and high-grade dysplasia) [3]. These stages are marked by progressive loss of mucin expression (MUC5AC, MUC6), emergence of intestinal markers (CDX2, MUC2), and rising Ki-67 proliferation indices, reflecting increasing malignant potential [3]. According to research results, eradication of H. pylori can alleviate chronic active inflammation of the stomach and reduce the incidence of gastric cancer in the population by approximately 37 % [4]. However, the global rise in antibiotic resistance has severely compromised the efficacy of standard regimens. First-line triple therapy, once highly effective, now faces failure rates exceeding 30 % in many regions, primarily due to the high prevalence of clarithromycin, and metronidazole-resistant strains [5,6]. H. pylori infection leads to inflammation through a variety of pathways, induced both in the gastric epithelial cells which they first contact and in circulating immune cells recruited to the site of infection. Currently, the treatment options available for H. pylori infection mainly use a combination of multiple antimicrobial drugs, proton pump inhibitors (PPIs), and Histamine-2 receptor antagonists (H2RAs), such as dual therapy, triple therapy, quadruple therapy, and sequential therapy [7]. However, the emergence of drug-resistant strains has led to a decrease in the eradication rate of H. pylori, treatment failure, or recurrence of infection [8]. In order to improve the eradication rate, the current clinical treatment regimen gradually increases the dosage of drugs, but it causes the further development of bacterial antibiotic resistance, resulting in gastrointestinal dysfunction and flora disturbance [9]. Therefore, the application of new technologies (such as biotechnology, information technology, etc.) has accelerated the development of new structures and high-efficiency antibioticsi [10]. A pivotal yet often overlooked driver of this treatment failure is the ability of H. pylori to form resilient biofilms within the gastric mucosa [11]. These structured microbial communities act as a physical and functional barrier, significantly reducing antimicrobial penetration and providing a niche for bacterial persistence. Biofilm-mediated resistance further diminishes the efficacy of conventional antibiotics, leading to persistent and recurrent infections that are notoriously difficult to eradicate [12,13]. This critical clinical gap necessitates the development of novel, non-antibiotic-dependent strategies that can specifically disrupt the biofilm barrier, target persistent bacteria, and overcome existing resistance mechanisms [14,15]. H. pylori biofilms are a key mechanism for antibiotic resistance, significantly prevent antimicrobial penetration, further increasing bacterial growth, prolonging infections duration, and enhancing resistance to host defenses and external stresses [[16], [17], [18], [19]]. The link between biofilms and antibiotic resistance has raised concerns among researchers [20,21], highlighting the need for new compounds to combat biofilms [22,23].

Naturally derived alkaloids belong to a class of quite significant organic compounds. Coptisine (COP), a benzyl tetrahydroisoquinoline alkaloid, is one of the major bioactive constituents in Coptis chinensis, which is a famous traditional Chinese medicine [24]. Antibacterial, anti-inflammatory, antioxidant, antimetabolic, and antigastrointestinal disease properties are exhibited by the isoquinoline alkaloid COP. Given the alarming rise in antibiotic resistance, its potential as a new treatment for bacterial infections stems from the fact that it inhibits bacterial growth while simultaneously disrupting the integrity of cell membranes [25,26]. Gram-positive and gram-negative bacteria are both efficiently eliminated by COP. Because it ruptures the bacterial cell membrane, which raises ROS and results in cell death, COP exhibits promise as a natural remedy. This could lessen the inflammatory reaction brought on by illnesses brought on by dangerous bacteria [25]. However, its therapeutic potential is hampered by poor aqueous solubility and limited bioavailability. Therefore, encapsulation of COP within an engineered nano-hybrid protects the compound, enhances its delivery to the infection site, and leverages the nanocarrier's synergistic mechanisms. Further investigation of coptisine is necessary to facilitate the application of coptisine-based drugs in clinical practice.

Recently, nanotechnology-based approaches, particularly lipid-based nano-systems like liposomes, have shown notable advantages regarding their physicochemical properties and safety considerations. Liposomes are vesicular structures featuring concentric bilayers made from materials that are generally biocompatible and biodegradable. Their unique characteristics provide several advantages over alternative delivery systems, including the ability to incorporate both hydrophilic and hydrophobic drugs, as well as features such as biocompatibility, biodegradability, low toxicity, and minimal activation of the immune system [27,28]. In addition, cell membrane receptors, antibodies, proteins, and enzymes are all possible targeting platforms that can be easily combined with liposomes. This allows for the targeted delivery of bioactive chemicals to specific infection sites [[29], [30], [31]]. However, conventional liposomes often suffer from limited mucoadhesive properties and are susceptible to rapid clearance from the dynamic gastric environment, which can drastically reduce their residence time at the site of H. pylori colonization and biofilm formation.

Biocompatible and ecologically friendly lignin nanoparticles (LIGNPs) are being developed as drug delivery vehicles. These nanoparticles are highly effective against both Gram-negative and Gram-positive bacteria, including H. pylori, E. coli, K. pneumoniae, P. aeruginosa, and Mannheimia haemolytica [32]. Their antioxidant properties and capacity to encapsulate and stabilize bioactive compounds enhance the stability and controlled release of therapeutics, positioning them as a promising alternative to traditional systems [33]. By interfering with bacterial cell membranes and metabolic activities, LIGNPs show strong antibacterial activity; this increases their effectiveness against infections, and their biodegradability promotes sustainable medical practices [34]. Despite these benefits, LIGNPs can face challenges related to achieving optimal and sustained drug release kinetics for some therapeutic agents. Furthermore, their inherent physicochemical properties can sometimes lead to aggregation, potentially compromising their efficacy as a standalone delivery platform.

To overcome the individual limitations of these systems and create a synergistic platform, we rationally designed a hybrid nanocarrier. The combination of liposomes and lignin nanoparticles is strategic: the liposomal component offers a robust, biocompatible vesicle for high-efficiency encapsulation and controlled release of hydrophobic drugs, while the integrated lignin core concurrently provides strong mucoadhesion for prolonged gastric retention and contributes inherent antibacterial and biofilm-disrupting capabilities. This design leverages the strengths of each material to compensate for the other's weaknesses, resulting in a system with superior overall functionality for targeting H. pylori biofilms. The COP-LIG@LIPSNCs were engineered using a modified thin-film hydration and embedding technique, where the pre-formed LIG NPs are integrated directly into the phospholipid bilayers of the liposomes. This results in a core-shell-like structure where the lignin core contributes its robust antibacterial and biofilm-disrupting properties, while the liposomal shell ensures high encapsulation efficiency and controlled release of the hydrophobic drug, coptisine. A key feature of this design is the conferred bioadhesiveness, which is intrinsically derived from the lignin component. The rich polyphenolic surface and high density of hydroxyl groups on the embedded LIGNPs facilitate strong, non-covalent interactions (e.g., hydrogen bonding, hydrophobic interactions) with mucin glycoproteins in the gastric mucosa. This mechanism is designed to significantly prolong gastric residence time, a critical factor for effectively eradicating biofilm-based infections. This study aimed to engineer bio-adhesive lignin-liposome nanocarriers (COP-LIG@LIPSNCs) for targeted gastric delivery of COP. We sought to evaluate their synergistic mechanisms including biofilm penetration, membrane disruption, and oxidative stress mitigation against H. pylori, and validate their therapeutic efficacy in vitro and in vivo as an alternative to conventional therapies.