The unique biological and physicochemical properties of carbon nanotubes (CNT) make them an ideal nanocarrier material for the biologically antibacterial active substance. It is a tubular hollow structure containing sheets of graphene rolled together at discrete and specific angles. Depending on the number of graphene sheets rolled together, carbon nanotubes are classified as single-walled and multi-walled carbon nanotubes. These tubes can have a cross-sectional diameter of 0.4–100 nm, while the length of the tube extends thousands of times the diameter. In nano-delivery systems, such carbon nanotubes have a high aspect ratio, ultra-light specific surface area, nano-needle-like structure, and a wide range of application prospects (17). The structural stability, flexibility and surface modification of functionalized nanotubes make them good carriers of active substances. Under this concept, functionalized carbon nanotubes are widely used to encapsulate or connect antibacterial active substances. The carbon nanotubes also have superior antibacterial properties (18). To enhance the antibacterial activity of multi-walled carbon nanotube (MWCNT), modification of MWCNT is necessary. Chen Yuan et al. (19) applied a nanohybrid comprising silver nanoparticles within dendritic poly(amidoamine) dendrimer-modified MWCNT as an antimicrobial solution against Gram-negative and Gram-positive bacteria.

Hence Ghahremani was inspired by mussels to design a novel nanocarrier consisting of polydopamine (PDA), chitosan (CH) and zinc cations modified on the surface of multi-walled carbon nanotubes (MWCNT) (20). PDA, CH and Zn²⁺ were found to be successfully modified on the oxidized multi-walled carbon nanotube (OMWCNT) surface employing characterization. The material was incorporated into an epoxy coating to form a nanocomposite that exhibited superior barrier capabilities and provided stable corrosion inhibition for nearly 9 weeks.

Au nanoparticle (AuNP) carriers construct an effective delivery medium that can be applied in different fields, and gold nanoparticles have different anisotropic properties such as nanostars, nanorods, nanocages, nanoshells, and nano prisms (21–23). Among the many properties of gold nanocarriers, their optical properties are the primary factor that attracts them to biomedical and food applications. It enables the attachment of different biomolecules to gold nanoparticles. Such as enzymes, carbohydrates, fluorophores, peptides, proteins and genes. This enables efficient intracellular transport of molecules to overcome relevant barriers (24).

Au nanoparticles revealed a noteworthy antimicrobial effect against Gram-positive and Gram-negative bacterial strains. Usually, the negatively charged surface of the bacterial cell wall is attracted to the positively charged nanoparticles due to the electrostatic force of the interaction (25). In contrast, gold nanoparticles create strong bonds with the bacterial cell membrane, leading to the rupture of the cell wall and cell membrane, which leads to the disruption of biological processes. The bonds formed between metal ions and biomolecules are reported to be indeterminate and gold nanoparticles exhibit broad-spectrum activity (26, 27).

The advantages of synthesizing gold nanoparticles from active substances extracted from vegetables are not limited to the reduction of environmental toxicity, the production of nanoparticles in large quantities, the simplicity of reducing metal salts, the rapidity, the economic efficiency, the safety of clinical studies, and the nanoparticles are other advantages associated with this synthetic method. Aderonke used active substances extracted from vegetables in combination with gold nanoparticles to prepare a nanoparticle with good antibacterial effect. The percentage inhibition zones of the synthesized gold nanoparticles against the tested fungi and bacteria ranged from 30 to 66% and 40 to 54%, respectively (27).

Quantum dots (QD) include atoms in the II-VI (Se, Zn, Te, Cd) or III-V (in, As, P) elemental groups of the periodic table. They are colloidal nanocrystals and energy donors. The size of the quantum dots changes the luminescence between the UV–NIR region, i.e., smaller quantum dots (2 nm) fluoresce blue and larger ones (5 nm) fluoresce red (28). This optical property with long-time light emission and less photobleaching makes it superior to other organic dyes, which allows it to be used for cell imaging. Normally, the toxic cadmium in Cd Se quantum dots is encapsulated within a ZnS shell to protect it from toxicity. This enhances the accumulation of nanoparticles at the desired vascular sites. These quantum dots are also considered to be efficient delivery and reporting systems.

Chitosan is a polycationic polymer derivative of chitin, prepared by alkaline deacetylation of chitin. Besides cellulose, chitosan is the most abundant biopolymer existing in nature, and its structure consists of-d-glucosamine deacetylation unit and n -acetyl- d -glucosamine acetylation unit linked by β- (1, 4) glycosidic bond. Chitosan and its nanoparticles have good bioactivity and loading capacity and have been gaining more and more attention in pharmaceutical and functional food applications (29), where it has been found that the nanoparticles not only have good loading capacity for antibacterial active substance but also have outstanding slow-release properties (30).

Starch has been widely used in food, textile and pharmaceutical fields under its wide source, low cost and high biocompatibility (31, 32). However, natural starch has a large relative molecular weight, poor enzymatic resistance, and does not contain hydrophobic groups, so direct preparation of nanocarriers from natural starch for functional factor encapsulation has a limited application. The starch structure can be easily modified and its molecular fine structure can be targeted and regulated according to the properties of functional factors to prepare starch nanocarriers to achieve effective encapsulation. The starch nanocarriers can be prepared for the purpose of effective embedding. Starch nanocarriers are generally in the form of starch nanoparticles, starch nanocrystals (33), starch nanofibers (34), and nanostructured starch. The starch nanocarrier forms generally include starch nanoparticles, starch nanocrystals, starch nanofibers and nanostructured starch.

Protein is a biological macromolecule with multiple moieties and is characterized by a variety of chemical and physical spatial structures that can interact with a variety of food functional factors. Therefore, proteins are excellent carriers for the delivery of food active ingredients. Therefore, proteins are excellent carriers for the delivery of food active ingredients (such as curcumin), and they are also hot materials for the research of food colloidal delivery systems in recent years. The most widely used protein nano-delivery systems are animal proteins, plant proteins, and protein peptides.

Metal–organic framework materials (MOFs) are crystalline materials with a three-dimensional mesh structure formed by inorganic substituents (metal clusters, metal ions, central chains) and organic ligands, through coordination bonds. MOFs are an important component of hybrid nanomaterials. The most commonly used MOFs material sofistitute Lavoisier frameworks (MILs series), isoreticular metal–organic frameworks (IRMOFs series), zeolite imidazole frameworks (ZIFs series), etc. As Figure 3 shows the typical material diagram of different kinds of MOFs. Compared with traditional porous materials such as activated carbon (AC), silica gel and molecular sieve, MOF materials have the advantages of high porosity, high adsorption capacity, large specific surface area, and high modifiability. In recent years, MOF materials have been used in drug encapsulation (36), biocatalysis (37), antibacterial preservation (38), etc. MOF materials can meet the requirements of high biocompatibility, degree of dispersion and targeting required for food biomedicine through surface modification, synthesis methods, ligand changes, etc.

For example, Zeinab combined curcumin with MOF materials to construct cyclodextrin-metal organic backbone nanomaterials (CD-MOFs). The stability of curcumin was improved by three orders of magnitude and exhibited superior active functions (39). Xiao ligated HKUST-1 with folic acid to make a hydrogel wound excipient, which played a better bactericidal effect and promoted wound healing. In summary, MOF materials are promising and valuable for research in food biomedical applications, and their versatile structures and multiple applications provide new ideas for solving some problems (40).

Hydrogels are three-dimensional solid networks made of physically or chemically cross-linked hydrophilic polymeric structures that can entangle large amounts of water or other biological fluids within their networks (41). The formation of hydrogel nanoparticles involves the self-assembly between different charged polymers through electrostatic interactions. In their production process, the liquid phase is gelled by temperature regulation, cross-linking agents or acidification or the addition of multivalent ions. They can encapsulate hydrophilic and lipophilic bioactive, prevent degradation and target release efficiently.

Nano-hydrogels have an extremely important role in the field of drug slow release, specifically in reducing the concentration fluctuation of drug solution and releasing the loaded drug smoothly. Adila prepared a carvacrol-containing hydrogel (GG-Carv), the combination of which promotes bioavailability and delivery while maximizing the antibacterial properties of carvacrol (42). Table 1 shows the Comparison and application of different nanomaterials.

Emulsification is the process of uniformly dispersing one liquid in very small droplets in another liquid that is immiscible (or partially immiscible) with each other. The organic polymer solution is homogenized with the aqueous phase and the solvent is then evaporated, leading to the precipitation of polymer molecules and the formation of nanospheres. This process of emulsification leads to nano emulsions loaded with active substances.

The polymer solution containing biological compounds is emulsified in the aqueous phase and then the solvent that previously dissolved the polymer is vaporized to produce nanospheres of precipitated polymer. The advantage of this method is that it is suitable for both hydrophilic and hydrophobic compounds with good solubilization ability, while the disadvantage is that this process requires a large amount of surfactant (62, 63). It provides a higher loading capacity for lipophilic compounds. Hydrophilic antibacterial active substances are poorly trapped and more difficult to scale up (64).

Squeeze gelation is a process in which a biopolymer solution is passed through a nozzle into a gelling environment. On a small scale, the biopolymer solution is loaded into a syringe and passed through a needle into the gel state to form a gel. The technique is also suitable for industrial scale and is a gentle and convenient method for the encapsulation of hydrophilic and hydrophobic compounds (65).

Zeng introduced catechins (CC) and proanthocyanidins (PC) into rice starch gels by extrusion gelation to explore the effects of polyphenol molecules on the structure of starch gel systems in hot extrusion 3D printing (66). Owing to the strong intermolecular interactions between polyphenol molecules and starch chains, the starch gel network structure was partially disrupted, leading to a decrease in viscosity and thus improving the extrudability of the starch gel.

Spray drying is one of the most popular embedding techniques for a variety of health food products. It can be used directly for hydrophilic ingredients or indirectly for oleophilic ingredients. This technique is beneficial for many applications because it converts the liquid feed into a dry powder, which usually has higher storage stability and is also easier to transport and store (67). In brief, the process of spray drying is that the fluid material is first pumped through the atomizer, which breaks it down into a stream of fine droplets, which are then rapidly dried by the heated gas flowing through the chamber, where the droplets dry and fall to the bottom of the chamber in a few seconds, and the resulting powder is drawn into the cyclone, which is connected to an outlet fan, and the dried air is passed through a filter to separate the very fine powder, which is then removed from the entire embedding process is completed with the discharge from the spray dryer. The main challenge of this technique is the viscosity of the biopolymer suspension, which may clog the atomizer and reduce the encapsulation yield (68). Application of modified chitosan (e.g., glycol chitosan) has been proposed to obtain better nanoparticles by this method (69).

Supercritical fluid technology is a new type of nanocarrier preparation technology. A supercritical fluid is a special state of fluid formed when the material is above its critical temperature and critical pressure (70). Carbon dioxide, nitrogen, methane, water, and other common gases and liquids can be used as supercritical fluids, and in the industrial application of supercritical fluid technology, the most used is supercritical carbon dioxide (SC-CO₂). SC-CO₂ is a new solvent with broad industrial application prospects (71). In addition, SC-CO₂ can be used not only as a solvent, antisolvent, and solute but also in applications in drug delivery, such as the formulation of polymeric nanocarriers in combination with different drug molecules. With its tunability above the critical pressure and temperature, it provides control over particle size, particle morphology, and drug loading (72).

Curcumin is an excellent antibacterial active substance and its antibacterial effect can be improved by combining it with different nanoparticles. Xie (73) prepared curcumin nanoparticles by supercritical CO₂, and this nano preparation This nanoparticle preparation showed higher solubility and enhanced antibacterial, antioxidant, and anticancer effects with a minimum inhibitory concentration (MIC) 50% lower than that of free curcumin solution.

Nanoprecipitation (FNP) relies on the spontaneous emulsification of the organic internal phase of the polymer or bioactive compound and organic solvent, accommodating the external phase that then enters the aqueous phase (74). The nanoprecipitation method prepares nanoparticles by controlled mixing of solute solution and non-solvent with rapid reaction and is suitable for the preparation of a wide range of nanoparticles. Ahmed (75) used FNP to encapsulate β-carotene in NPs via a food-grade protein (sodium caseinate). FNP showed significant advantages in controlling NP size and increasing β-carotene loading and stability. The internal structure of NPs can be tuned by the flow rate. The loose structure is accompanied by a high release of β-carotene, while the compact structure is accompanied by a slight release.

Sequential Deposition is the sequential processing of the donor and acceptor layers, thus allowing, on the one hand, the two active components to be individually regulated and optimized; on the other hand, weakening the interactions between the two components and reducing the complexity of the film formation kinetics, thus providing new opportunities for reducing production requirements. Widely used in the development of multilayer nanocarriers, with low cost, easy adoption, simple assembly techniques and better protection of lipophilic compounds (76).

Multilayer coconut oil–water emulsions containing curcumin were prepared and stabilized using a layer-by-layer technique assembled using multilayer gelatin, gum Arabic and tannic acid. Thus, the ability to control interfacial film properties by combining electrostatic, hydrophobic and hydrogen-bonding interactions may be able to control the physical stability, payload retention and accessibility of multilayer emulsions.