A chitosan-coated liposome encapsulating antibacterial peptide, Apep10: characterisation, triggered-release effects and antilisterial activity in thaw water of frozen chicken

Development, Characterization, and Antimicrobial Evaluation of Hybrid Nanoparticles (HNPs) Based on Phospholipids, Cholesterol, Colistin, and Chitosan Against Multidrug-Resistant Gram-Negative Bacteria

Background: Colistin, a lipopeptide antibiotic usually used as a last resort against multidrug-resistant bacterial strains, has also begun to address the challenge of antimicrobial resistance. Objective: this study evaluates whether hybrid nanoparticles (HNPs) composed of Phospholipon® 90G, cholesterol, and colistin can enhance its effectiveness against resistant clinical isolates of Klebsiella pneumoniae, a clinically significant Gram-negative bacterium. Methods: HNPs were developed using the ethanol injection method and coated with chitosan through a layer-by-layer technique. HNP characterization included measurements of particle size, polydispersity index (PDI), and zeta potential, along with thermal (DSC) and spectrophotometric (FT-IR) analyses. Ultrafiltration and ATR-FTIR were employed to assess colistin's association and release efficiencies. The biological evaluation followed CLSI guidelines. Results: uncoated hybrid nanoparticles (U-HNP) and chitosan-coated hybrid nanoparticles (Ch-HNP) described monodisperse populations, with respective PDI values of ~0.124 and ~0.150, Z-averages of ~249 nm and ~250 nm, and zeta potential values of +17 mV and +20 mV. Colistin's association and release efficiencies were approximately 79% and 10%, respectively. Regarding antimicrobial activity, results showed that colistin as part of HNPs is poorly effective against this microorganism. However, in the most resistant strain, colistin activity increased slightly when the HNP was coated with chitosan. Conclusions: HNPs described high stability against disaggregation, limiting the colistin release and, therefore, affecting antimicrobial performance.

Preparation, characterization and properties of chitosan-coated Epsilon-poly-lysine nanoliposomes in apple juice

Epsilon-poly-lysine (EPL) is widely used in food preservatives. However, EPL can react with components in food substrates, resulting in the formation of precipitates that reduce its antimicrobial properties. Nanoencapsulation is a promising technique and represents a novel approach to enhance EPL activity. In this study, EPL nanoliposomes (EPLLP) were prepared by the thin film hydration method, and chitosan-coated nanoliposomes (CS-EPLLP) were developed by modifying EPLLP with 0.5 mg/mL chitosan. The obtained CS-EPLLP exhibited a spherical morphology with a particle size range of 85.27-89.77 nm, a polydispersity index (PDI) of 0.293-0.301, and an encapsulation efficiency of 83.01 ± 4.00 %. After 30 days of storage, no significant difference in particle size was observed and the PDI was <0.30. The release rate of EPLLP was up to 40 % in 1 h, while that of CS-EPLLP was <20 %. The physical and thermal stability of EPLLP could be effectively improved by chitosan. Moreover, CS-EPLLP could effectively eradicate A. acidocaldarius and A. acidoterrestris in apple juice at concentrations of 2.5 and 0.625 mg/L, respectively. The cytotoxicity test showed that CS-EPLLP exhibited excellent biocompatibility. Therefore, this study has developed a novel nanoliposome material that provides new insights into the control of bacterial contamination in fruit juices.

Encapsulation of lemongrass essential oil by bilayer liposomes based on pectin, gum Arabic, and carrageenan: Characterization and application in chicken meat preservation

The volatile characteristics of lemongrass essential oil (LO) have seriously hindered its further application, and encapsulation it with multilayer modified liposomes may be an effective strategy to improve this dilemma. This study selected chitosan (CH) and three anionic polymers, pectin (P) / gum arabic (GA) / carrageenan (C), as the first and second coating polymers to modify nano liposomes (NL) by layer-by-layer electrostatic deposition, obtaining three bilayer liposomes, P-CH-NL, GA-CH-NL, and C-CH-NL as high-quality stabilized carriers of LO. The bilayer liposomes showed a dense membrane structure ranging from 110 to 150 nm uniformly, with good antioxidant properties. All bilayer liposomes had good stability during 28-day storage at 4 °C, while C-CH-NL performed relatively better inferred by smaller changes of size, PDI and Zeta potential. The total volatile base nitrogen (TVB-N) values of fresh chicken meat and a total number of bacterial colonies (TBC) experiments showed that GA-CH-NL and C-CH-NL could better retard the increase of volatile salt base nitrogen. All bilayer liposomes could delay the time for the total bacterial count to exceed 6 log CFU/g (from 7 days to 10 / 12 days). Therefore, the bilayer liposomes P-CH-NL, GA-CH-NL, and C-CH-NL may be promising natural preservatives for food products.

Chitosan-Coated Liposome Formulations for Encapsulation of Ciprofloxacin and Etoposide

Cancer and bacterial infections rank among the most significant global health threats. accounting for roughly 25 million fatalities each year. This statistic underscores the urgent necessity for developing novel drugs, enhancing current treatments, and implementing systems that boost their bioavailability to achieve superior therapeutic outcomes. Liposomes have been recognised as effective carriers; nonetheless, they encounter issues with long-term stability and structural integrity, which limit their pharmaceutical applicability. Chitosomes (chitosan-coated liposomes) are generally a good alternative to solve these issues. This research aims to demonstrate the effective individual encapsulation of ciprofloxacin (antibacterial, hydrophilic) and etoposide (anticancer, hydrophobic), within chitosomes to create more effective drug delivery systems (oral administration for ciprofloxacin, parenteral administration for etoposide). Thus, liposomes and chitosomes were prepared using the thin-film hydration technique and were characterised through ATR-FTIR, Dynamic Light Scattering (DLS), zeta potential, and release profiling. In both cases, the application of chitosomes enhanced long-term stability in size and surface charge. Chitosome-encapsulated ciprofloxacin formulations exhibited a slower and sustained release profile, while the combined effect of etoposide and chitosan showed heightened efficacy against the glioblastoma cell line U373. Therefore, coating liposomes with chitosan improved the encapsulation system's properties, resulting in a promising method for drug delivery.

Ceftazidime and Usnic Acid Encapsulated in Chitosan-Coated Liposomes for Oral Administration against Colorectal Cancer-Inducing Escherichia coli

Escherichia coli has been associated with the induction of colorectal cancer (CRC). Thus, combined therapy incorporating usnic acid (UA) and antibiotics such as ceftazidime (CAZ), co-encapsulated in liposomes, could be an alternative. Coating the liposomes with chitosan (Chi) could facilitate the oral administration of this nanocarrier. Liposomes were prepared using the lipid film hydration method, followed by sonication and chitosan coating via the drip technique. Characterization included particle size, polydispersity index, zeta potential, pH, encapsulation efficiency, and physicochemical analyses. The minimum inhibitory concentration and minimum bactericidal concentration were determined against E. coli ATCC 25922, NCTC 13846, and H10407 using the microdilution method. Antibiofilm assays were conducted using the crystal violet method. The liposomes exhibited sizes ranging from 116.5 ± 5.3 to 240.3 ± 3.5 nm and zeta potentials between +16.4 ± 0.6 and +28 ± 0.8 mV. The encapsulation efficiencies were 51.5 ± 0.2% for CAZ and 99.94 ± 0.1% for UA. Lipo-CAZ-Chi and Lipo-UA-Chi exhibited antibacterial activity, inhibited biofilm formation, and preformed biofilms of E. coli. The Lipo-CAZ-UA-Chi and Lipo-CAZ-Chi + Lipo-UA-Chi formulations showed enhanced activities, potentially due to co-encapsulation or combination effects. These findings suggest potential for in vivo oral administration in future antibacterial and antibiofilm therapies against CRC-inducing bacteria.

Nanoliposomal delivery systems of natural antibacterial compounds; properties, applications, and recent advances

Todays, nanoliposomes (NLPs) are considered as one of the most efficient nanocarriers to deal with bacteria, practically in food products. These nanodelivery systems are able to be loaded with different bioactive compounds. The main aim of this review is investigating recent approaches (mostly from the years of 2018 to 2022) regarding development of nanoliposomal natural antibacterial compounds. In this regard, NLPs alone, combined with films, coatings, or fibers, and in coated forms are reviewed as advanced delivery systems of antibacterial substances. Moreover, a robust and comprehensive coverage of the morphological and physical properties of formulated NLPs as well as their interactions with antibacterial substances are discussed. The importance of NLPs to encapsulate antibacterial ingredients, advantages and drawbacks, antibacterial pathways of formulated NLPs, and comparison of them with pure antibacterial bioactive compounds are also explained.

Lipid-Based Nanostructures for the Delivery of Natural Antimicrobials

Encapsulation can be a suitable strategy to protect natural antimicrobial substances against some harsh conditions of processing and storage and to provide efficient formulations for antimicrobial delivery. Lipid-based nanostructures, including liposomes, solid lipid nanoparticles (SLNs), and nanostructured lipid nanocarriers (NLCs), are valuable systems for the delivery and controlled release of natural antimicrobial substances. These nanostructures have been used as carriers for bacteriocins and other antimicrobial peptides, antimicrobial enzymes, essential oils, and antimicrobial phytochemicals. Most studies are conducted with liposomes, although the potential of SLNs and NLCs as antimicrobial nanocarriers is not yet fully established. Some studies reveal that lipid-based formulations can be used for co-encapsulation of natural antimicrobials, improving their potential to control microbial pathogens.

Biopolymer-liposome hybrid systems for controlled delivery of bioactive compounds: Recent advances

Conventional liposomes still face many challenges associated with the poor physical and chemical stability, considerable loss of encapsulated cargo, lack of stimulus responsiveness, and rapid elimination from blood circulation. Integration of versatile functional biopolymers has emerged as an attractive strategy to overcome the limitation of usage of liposomes. This review comprehensively summarizes the most recent studies (2015-2020) and their challenges aiming at the exploration of biopolymer-liposome hybrid systems, including surface-modified liposomes, biopolymer-incorporated liposomes, guest-in-cyclodextrin-in-liposome, liposome-in-hydrogel, liposome-in-film, and liposome-in-nanofiber. The physicochemical principles and key technical information underlying the combined strategies for the fabrication of polymeric liposomes, the advantages and limitations of each of the systems, and the stabilization mechanisms are discussed through various case studies. Special emphasis is directed toward the synergistic efficiencies of biopolymers and phospholipid bilayers on encapsulation, protection, and controlled delivery of bioactives (e.g., vitamins, carotenoids, phenolics, peptides, and other health-related compounds) for the biomedical, pharmaceutical, cosmetic, and functional food applications. The major challenges, opportunities, and possible further developments for future studies are also highlighted.

Preparation, characterization and release behavior of chitosan-coated nanoliposomes (chitosomes) containing olive leaf extract optimized by response surface methodology

This study was dedicated to the optimization and preparation of chitosan-coated liposomes (chitosomes) as promising nanocarriers for retention of olive leaf extract optimized by Response surface methodology (RSM) based on central composite design. Accordingly, the best sample was chosen for further tests with the encapsulation efficiency, stability and electrical conductivity of 94%, 98% and 9.545 mS respectively. The average size of the optimal chitosome and nanoliposome were lower than 100 nm and the zeta potential was altered from a negative charge to positive after addition coating process with chitosan. Moreover, the differential scanning calorimetry of blank and loaded chitosome revealed the increase of fluidity and lower temperature of phase transition in loaded chitosome compared to blank one. FTIR spectra demonstrated that electrostatic interactions and hydrogen bonds occur between phospholipid polar groups, chitosan amine moieties and major olive leaf extract polyphenols including oleuropein and hydroxy tyrosol. Furthermore, the optimal loaded chitosome had the highest stability during 25 days at the temperature of 4 °C. Finally, the in vitro release tests were best fitted with Peppas-Sahlin and Kopcha models in food simulants and gastrointestinal simulated juice respectively revealing erosion-based release model.

Supplementary Information

The online version contains supplementary material available at (10.1007/s13197-021-04972-2).

Self-assembled lipids for food applications: A review

Lipids play an important role in human nutrition. Several foodstuffs can be manufactured from the simple, compound and derived lipids. In particular, the use of self-assembled lipids (SLs, e.g. self-assembled L-α-lecithin) has brought great attention for the development of tailored, tuned and targeted colloidal structures loading degradation-sensitive substances with valuable antimicrobial, antioxidant and nutraceutical properties for food applications. For example, polyunsaturated fatty acids (PUFAs) and essential oils can be protected from degradation, thus improving their bioavailability in general terms in consumers. From a nanotechnological point of view, SLs allow the development of advanced and multifaceted architectures, in which each molecule of them are used as building blocks to obtain designed and ordered structures. It is important to note before beginning this review, that simple and compound lipids are the main SLs, while essential fatty acids and derived lipids in general have been considered by many research groups as the bulk loaded substances within several structures from self-assembled carbohydrates, proteins and lipids. However, this review paper is addressed on the analysis of the lipid-lipid self-assembly. Lipids can be self-assembled into various structures (micelles, vesicular systems, lyotropic liquid crystals, oleogels and films) to be used in different food applications: coatings, controlled and sustained release materials, emulsions, functional foods, etc. SLs can be obtained via non-covalent chemical interactions, primarily by hydrogen, hydrophilic and ionic bonding, which are influenced by the conditions of ionic strength, pH, temperature, among others. This manuscript aims to give an analysis of the specific state-of-the-art of SLs for food applications, based primarily on the literature reported in the past five years.

Towards Robust Delivery of Antimicrobial Peptides to Combat Bacterial Resistance

Antimicrobial peptides (AMPs), otherwise known as host defence peptides (HDPs), are naturally occurring biomolecules expressed by a large array of species across the phylogenetic kingdoms. They have great potential to combat microbial infections by directly killing or inhibiting bacterial activity and/or by modulating the immune response of the host. Due to their multimodal properties, broad spectrum activity, and minimal resistance generation, these peptides have emerged as a promising response to the rapidly concerning problem of multidrug resistance (MDR). However, their therapeutic efficacy is limited by a number of factors, including rapid degradation, systemic toxicity, and low bioavailability. As such, many strategies have been developed to mitigate these limitations, such as peptide modification and delivery vehicle conjugation/encapsulation. Oftentimes, however, particularly in the case of the latter, this can hinder the activity of the parent AMP. Here, we review current delivery strategies used for AMP formulation, focusing on methodologies utilized for targeted infection site release of AMPs. This specificity unites the improved biocompatibility of the delivery vehicle with the unhindered activity of the free AMP, providing a promising means to effectively translate AMP therapy into clinical practice.

Micro/nanoencapsulation strategy to improve the efficiency of natural antimicrobials against Listeria monocytogenes in food products

Listeria monocytogenes (Lm), the etiological agent of listeriosis diseases in humans, is a serious pathogenic microorganism threatening the food safety especially in ready-to-eat food products. Adhesion on both biotic and abiotic surfaces is making it a potential source of contamination by Lm. Also, this bacterium has become more tolerant in food processing conditions, including in the presence of adverse conditions such as cold and dehydration. One of the attractive and effective methods to inhibit the growth of Lm in the food products is using natural antimicrobial agents, which can be a suitable alternative to synthetic preservatives for producing organic food products. The use of pure natural antimicrobials has some limitations including low stability against harsh conditions, low solubility and absorption, and un-controlled release, which can decrease their functions. These limitations have been overcome by using new advanced encapsulation techniques, which have boosted the anti-listerial activity of natural agents. Therefore, the current paper is aiming to review the results of recent studies conducted on using natural antimicrobials added directly or as encapsulated forms into the food formulation to control the growth of Lm. The information of current study can be used by the researchers as well as the food companies for the optimization of food formulations through encapsulation strategies to control Lm and potentially produce safe foods for the consumers.

Encapsulation Systems for Antimicrobial Food Packaging Components: An Update

Antimicrobially active packaging has emerged as an effective technology to reduce microbial growth in food products increasing both their shelf-life and microbial safety for the consumer while maintaining their quality and sensorial properties. In the last years, a great effort has been made to develop more efficient, long-lasting and eco-friendly antimicrobial materials by improving the performance of the incorporated antimicrobial substances. With this purpose, more effective antimicrobial compounds of natural origin such as bacteriocins, bacteriophages and essential oils have been preferred over synthetic ones and new encapsulation strategies such as emulsions, core-shell nanofibres, cyclodextrins and liposomes among others, have been applied in order to protect these antimicrobials from degradation or volatilization while trying to enable a more controlled release and sustained antimicrobial action. On that account, this article provides an overview of the types of antimicrobials agents used and the most recent trends on the strategies used to encapsulate the antimicrobial agents for their stable inclusion in the packaging materials. Moreover, a thorough discussion regarding the benefits of each encapsulation technology as well as their application in food products is presented.

Nanosystems as Vehicles for the Delivery of Antimicrobial Peptides (AMPs)

Recently, antimicrobial peptides (AMPs), also called host defence peptides (HDPs), are attracting great interest, as they are a highly viable alternative in the search of new approaches to the resistance presented by bacteria against antibiotics in infectious diseases. However, due to their nature, they present a series of disadvantages such as low bioavailability, easy degradability by proteases, or low solubility, among others, which limits their use as antimicrobial agents. For all these reasons, the use of vehicles for the delivery of AMPs, such as polymers, nanoparticles, micelles, carbon nanotubes, dendrimers, and other types of systems, allows the use of AMPs as a real alternative to treatment with antibiotics.

Evaluation of the Antimicrobial Activity of Cationic Peptides Loaded in Surface-Modified Nanoliposomes against Foodborne Bacteria

Bacteria are a common group of foodborne pathogens presenting public health issues with a large economic burden for the food industry. Our work focused on a solution to this problem by evaluating antibiotic activity against two bacteria (Listeria monocytogenes and Escherichia coli) of relevance in the field of foodstuffs. We used two approaches: (i) structural modification of the antimicrobial peptides and (ii) nano-vehiculisation of the modified peptides into polymer-coated liposomes. To achieve this, two antimicrobial peptides, herein named ‘peptide +2′ and ‘peptide +5′ were synthesised using the solid phase method. The physicochemical characterisation of the peptides was carried out using measurements of surface tension and dynamic light scattering. Additionally, nanoliposomes were elaborated by the ethanol injection method and coated with a cationic polymer (Eudragit E-100) through the layer-by-layer process. Liposome characterisation, in terms of size, polydispersity and zeta potential, was undertaken using dynamic light scattering. The results show that the degree of hydrophilic modification in the peptide leads to different characteristics of amphipathicity and subsequently to different physicochemical behaviour. On the other hand, antibacterial activity against both bacteria was slightly altered after modifying peptide sequence. Nonetheless, after the encapsulation of the peptides into polymer-coated nano-liposomes, the antibacterial activity increased approximately 2000-fold against that of L. monocytogenes.

The antibacterial and antibiofilm efficacies of a liposomal peptide originating from rice bran protein against Listeria monocytogenes

With the aim of exploring a natural antilisterial peptide from food-derived origin, an antibacterial peptide named as Alpep7 was purified from the bromelain hydrolysate of rice bran protein (RBP) in this study. The resulting amino acid consequence was identified as KVDHFPL (Lys-Val-Asp-His-Phe-Pro-Leu) by ultraperformance liquid chromatography tandem matrix-assisted laser desorption/ionisation quadrupole time-of-flight mass spectrometry (MALDI Q-TOF MS). In addition, to assess the probability of the targeted delivery of liposome encapsulation of the peptide to Listeria biofilm, Alpep7-loaded liposomes were further prepared from a mixture of dipalmitoylphosphatidylcholine, stearylamine and cholesterol in a molar ratio of 10 : 3 : 2 and characterised by the analysis of particle size, zeta potential, microtopography and storage stability. The results showed that the liposomes exhibited a well-defined spherical shape, with an average diameter below 200 nm. The liposomes maintained favourable stability after storage at 4 °C for 4 weeks. Comparisons between the activities of free and liposomal Alpep7 via microbroth dilution, regrowth analysis and confocal scanning laser microscopy suggested that liposomal delivery was more effective during the initial exposure of the liposomes to the biofilms. The thermodynamic analysis indicated that the adsorption of liposomal Alpep7 to the listerial biofilm was a spontaneous, exothermic process. The results may provide a natural means for the treatment of listerial contamination and guide the potential application of liposomes for the targeted delivery of antimicrobials to pathogenic biofilms in the food industry.

Stabilization of a non-aqueous self-double-emulsifying delivery system of rutin by fat crystals and nonionic surfactants: preparation and bioavailability study

Literature examples of non-aqueous Pickering emulsions stabilized by fat crystals are very rare. Moreover, the applications of rutin are limited due to its low solubility in both water and oils (less than 0.10 mg g^-1 and 0.25 mg g^-1, respectively). Thus, herein, we developed an optimum formulation of a non-aqueous self-double-emulsifying delivery system (SDEDS) containing rutin and evaluated its oral bioavailability. The new formulation stabilized by fat crystals (glycerol monostearate, GMS) and nonionic surfactants was prepared via a two-step emulsification process. The presence of a mixture of GMS crystals and nonionic surfactants effectively improves the stability of the emulsions. The non-aqueous SDEDS spontaneously forms oil-in-oil-in-water (O/O/W) double emulsions in the gastrointestinal environment with the inner oil phase mainly containing the active ingredients. It is stable at both 4 °C and 25 °C for 30 days and could enhance the dissolution properties of the active ingredients. Furthermore, the protection of rutin against digestion-mediated precipitation was observed when the formulation contained a high concentration of GMS crystals. The oral absolute bioavailability of rutin obtained from SDEDS (8.62%) is 1.76-fold higher than that of the actives suspension (4.90%). Thus, the non-aqueous SDEDS is an attractive candidate for the encapsulation of water-insoluble and simultaneously oil-insoluble nutrients (such as rutin) and for use in oral delivery applications.

Physical–chemical stability and in vitro digestibility of hybrid nanoparticles based on the layer-by-layer assembly of lactoferrin and BSA on liposomes

Novel hybrid nanoparticles fabricated by the layer-by-layer deposition of lactoferrin and BSA on nanoliposomes showed a higher physical–chemical stability and digestibility than bare liposomes.