Zhou Wei1, Chen Jie1, Si Zhihao1, Shen Fanglin1
Luo Xiongfang 2,3, Wang Wenjuan1, Gu Yue1, Meng Xinyi1
(1. School of Environmental Science and Engineering, Wuxi University, Wuxi, Jiangsu 214105, China);
2. Shaoxing University of Arts and Sciences, Shaoxing Key Laboratory of High Performance Fibers and Products, Shaoxing 312000, Zhejiang;
3. Shaoxing University of Arts and Sciences, National Engineering Research Center for Fiber Matrix Composites, Shaoxing Branch, Zhejiang 312000)
Summary:This article reviews the research progress on antibacterial functionalization modification of gelatin based composites using organic and inorganic materials. This article provides an overview of the antibacterial functionalization effects of animal and plant extracts, carbon dots, metal and metal compound nanoparticles, and other antibacterial agents on gelatin based composite materials both domestically and internationally. Summarized the application and future development trends of antibacterial functionalized gelatin based composite materials.
key word:Gelatin, antibacterial, composite materials, food packaging, medical and pharmaceutical
0. Preface
With the gradual deterioration of the environment, the problem of plastic pollution is becoming increasingly serious, and the global annual production of waste plastics is about 3 × 10eightt， It is expected that the accumulation of waste plastics in the environment will reach 1.20 × 10 by 2025tent. Traditional plastics made from petroleum resources cannot be degraded, and their production and usage are enormous, causing serious plastic pollution problems. The potential harm caused by microplastics cannot be ignored. Ordinary plastics have no antibacterial ability, and the majority of food spoilage is caused by foodborne pathogens coming into contact with food. Food packaging is an important source of disposable plastic waste, and the development of biodegradable materials with antibacterial properties is of great significance. In addition, during the COVID-19 that broke out at the end of 2019, a large number of disposable plastic medical supplies were produced, which caused widespread concern of relevant scholars on the antibacterial research of medical consumables. Therefore, biodegradable materials with antibacterial properties have great potential market and competitiveness in the fields of food packaging and medical medicine. Among many biodegradable materials, gelatin has low cost, wide sources, easy film formation, excellent properties such as gel forming ability, dispersion stability and water retention, and can be widely used in food packaging, drug delivery, dressings and other fields. Gelatin is a product of collagen degradation in animal bodies, containing a large number of hydrophilic groups such as hydroxyl and carboxyl groups. It has poor water resistance and high water absorption. As a protein, it is prone to bacterial growth in humid environments and is limited in fields such as food packaging and medical medicine. This article reviews the research on antibacterial functionalization of two types of gelatin based biodegradable materials, including organic modified materials (plant extracts, animal extracts) and inorganic modified materials (metal oxide nanoparticles, silver nanoparticles, carbon dots, etc.), both domestically and internationally.
Organic/gelatin based composite material
1.1 Plant extracts
At present, many plant extracts exhibit excellent antibacterial activity, and their active ingredients mainly include terpenes, phenols, polysaccharides, alkaloids, and other types. Different plant extracts, due to their unique and diverse antibacterial mechanisms, can cause damage to bacteria from different perspectives such as cell wall, cell membrane, DNA structure and function, and enzyme activity. They have broad-spectrum antibacterial properties and are not prone to developing drug resistance, making them highly promising for development and application.
1.1.1 Plant essential oils
Natural plant essential oils are a type of substance extracted from plant roots, leaves, or fruits that have a unique odor and are rich in phenolic and aldehyde ketone compounds. They are widely available, mostly non-toxic and harmless, easily degradable, have good antibacterial properties, and are not prone to developing drug resistance. It has varying degrees of inhibitory effects on microorganisms, including by affecting the structure and function of bacterial cell membranes, enzymes, and DNA, as shown in Figure 1.
Figure 1 Antibacterial mechanism of plant essential oils
Most plant essential oils have strong inhibitory effects on foodborne pathogens such as Escherichia coli, Listeria monocytogenes, Staphylococcus aureus, etc. Common ones are cinnamon essential oil, clove basil essential oil, oregano essential oil, thyme essential oil, mint essential oil, privet fruit essential oil, cumin essential oil, etc. Its inhibitory effect on foodborne pathogens is shown in Table 1.
Table 1 Inhibition effect of plant essential oils on foodborne pathogens
Due to the strong volatility of plant essential oils, their antibacterial effect and application range are limited. They can be combined with emulsifiers or other carriers first, and then prepared into composite materials with gelatin, as shown in Figure 2. Among them, PickeringlotionIt is a type of emulsion formed by irreversible adsorption of biopolymer colloidal particles, forming a dense filling layer and stabilizing the interface. It can effectively prolong the sustained release time of antibacterial active ingredients such as plant essential oils and increase stability to prolong the antibacterial effect of materials. There are many materials that can enhance the comprehensive properties of gelatin matrix composites, such as chitin, chitosan, bacterial cellulose, etc., which can be used as stabilizers to prepare Pickering lotion encapsulated vegetable essential oil.
Figure 2 Pickering lotion encapsulates essential oil and prepares composite materials
1.1.2 Polyphenols
Plant polyphenols are a type of secondary metabolite with a polyphenolic structure, widely present in the fruits, leaves, shells, and seed coats of plants. They are a natural antibacterial agent with strong inhibitory effects on foodborne pathogenic microorganisms. The main components include flavonoids, tannins, phenolic acids, and flavonoids.
(1) Curcumin. Curcumin is a polyphenol with a wide range of biological properties, possessing excellent antibacterial activity and antioxidant properties. Moreover, curcumin solutions can exhibit different colors in different pH environments, making it a novel pH indicator dye. Based on these characteristics of curcumin, a certain amount of curcumin can be added to natural polymer films to give them antibacterial, antioxidant, and indicator functions. Shibin S et al. developed a curcumin functionalized polycaprolactone and gelatin composite fiber membrane. Research has shown that as the dosage of curcumin increases from 1% to 10%, the antibacterial rates of the composite material against Staphylococcus aureus and Escherichia coli increase from 43.2% ± 4.5% to 93.8% ± 0.7% and 28.5% ± 1.7% to 80.2% ± 25.5%, respectively. Studies have also shown that curcumin and gelatin have good compatibility and can form stable structures through interactions.
(2) Tea polyphenols and their extracts. Tea polyphenols are a general term for a class of polyphenolic mixtures with phenolic hydroxyl structures in tea, accounting for 18% to 36% of the total dry matter in tea. Catechins are the most important phenolic compounds in tea polyphenols, accounting for over 70% of the total. Among them, epigallocatechin gallate (EGCG) is the main active ingredient, accounting for about 50%. Many studies have shown that tea polyphenols, catechins, and EGCG have strong antibacterial and antioxidant activities, and can be combined with gelatin to prepare antibacterial active materials. Li et al. successfully prepared a drug sustained-release composite film (PGEC) consisting of polylactic acid co caprolactone (PLCL)/gelatin/EGCG/core-shell structure using coaxial electrospinning technology. Research has shown that gelatin provides many sites for hydrogen bonding with EGCG, making the composite membrane capable of effectively loading EGCG. The main mechanism is that negatively charged EGCG binds to positively charged bacterial lipopolysaccharide membrane and produces HtwoOtwoDestruction of bacterial cell walls. There are also studies showing that EGCG can inhibit bacterial growth by altering the osmotic pressure of the cell membrane.
1.1.3 Parvacrol/Thymol
Carvacrol and thymol are both volatile monoterpene phenols, and the main antibacterial components of oregano essential oil and thyme essential oil. They are isomers of each other, with antibacterial activity, and have inhibitory effects on most gram-positive and negative bacteria. Its antibacterial function can be achieved by destroying the cell wall and membrane, causing cytoplasmic leakage, and inhibiting cell biosynthesis.
Due to the high volatility and biodegradability of carvacrol, its application range is limited. It is necessary to improve the stability and antibacterial effect of carvacrol through appropriate packaging techniques or composite with other materials. Li Sen et al. used zein/casein (Z/CS) composite particles as a stabilizer to construct carvol Pickering lotion (CPE), and then blended CPE and gelatin to prepare a composite membrane with antibacterial activity. The results showed that when the amount of CPE added to the composite film was 5%, the diameters of the inhibition zones against Staphylococcus aureus and Escherichia coli were 37.30mm and 46.00mm, respectively, and the comprehensive performance of the composite film was the best.
1.2 Animal extracts
The animal extracts used for antibacterial modification of gelatin mainly include lysozyme, antimicrobial peptides, chitin, and its deacetylated derivative chitosan. Lysozyme and antimicrobial peptides both have antibacterial properties and are not prone to developing drug resistance. As protein and peptide molecules, they share structural similarities with gelatin and can form stable composite materials through appropriate crosslinking agents.
1.2.1 Lysozyme
Lysozyme, as a chemically stable protein macromolecule, is widely present in human secretions such as egg whites, tears, saliva, mucus, etc. It has the advantages of high activity, wide antibacterial spectrum, and low drug resistance. It can disrupt bacterial structure by hydrolyzing the β -1,4 glycosidic bond between N-acetylglucosamine (NAG) and N-acetylformamide (NAM) in the peptidoglycan of bacterial cell walls. The antibacterial effect of lysozyme is widely used in food and clinical settings, and can be immobilized on ligands and bound to various materials. Gelatin, as a protein macromolecule, can interact with it through crosslinking agents.
Kavur et al. improved the water retention and mechanical stability of gelatin (G) gel by adding soybean protein (SP) and inulin (IN), and added lysozyme (LYS) and nisin (NIS) to blend with gelatin based hydrogel to improve the antibacterial properties of the composite. After 14 days in the culture dish, the colony counts of the G/LYS and G/NIS groups were 5.8 logCFU/mL and 2.5 logCFU/mL, respectively, while the colony count of the G/LYS+NIS group was 1.3 logCFU/mL, indicating a significant improvement in antibacterial effect.
1.2.2 Antimicrobial Peptides
Antimicrobial peptides (AMPs) are a class of small molecule peptides with a wide range of sources and antibacterial activity, and are key effector molecules in the innate immune systems of prokaryotes and fungi. Its antibacterial mechanism mainly includes: inhibiting bacterial cell wall formation, disrupting cell membrane structure, interfering with nucleic acid and protein synthesis, and inhibiting enzyme activity. Due to its unique antibacterial mechanism and lack of drug resistance, it can be combined with gelatin materials to prepare antibacterial composite films. It is a substance with great potential for application and has broad prospects in food safety, medical and pharmaceutical fields. Milad et al. prepared a silk fibroin/gelatin bilayer sponge scaffold and loaded it with cationic antimicrobial peptide (CM11 peptide) for use as a wound dressing. The experimental results showed that the composite material with an antimicrobial peptide concentration of 16 μ g/mL exhibited good mechanical properties, high water absorption, high biodegradation rate, and good antibacterial activity. The inhibition zone diameters against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa were 10.80, 10.00, and 9.40mm, respectively.
2 Inorganic/Gelatin based Composite Materials
2.1 Metal oxide nanoparticles
Metal oxide nanoparticles have various properties such as biology, chemistry, magnetism, and optics, and have attracted widespread attention from researchers. Its antibacterial performance is excellent, and it can produce antibacterial effects by contacting and damaging cell membranes, entering cells to generate oxidative stress reactions, damaging DNA, and inhibiting enzyme activity. At present, the metal oxides mainly used for antibacterial modification of gelatin include zinc oxide nanoparticles, copper oxide nanoparticles, iron oxide nanoparticles, nickel oxide nanoparticles, manganese dioxide nanoparticles, and titanium dioxide nanoparticles.
2.1.1 Zinc oxide nanoparticles
Nano zinc oxide has strong antibacterial properties and can be widely used in medical and food fields such as drug delivery, medical equipment, and food transportation. The antibacterial mechanism is generally believed to be the production of reactive oxygen species (ROS), which oxidize bacterial cell membranes and release ions that bind to the cell membrane, altering its permeability. The antibacterial functionalization modification of gelatin based composite materials can be achieved by adding zinc oxide, enhancing the inherent properties of the materials and improving their application fields. Rahim et al. prepared antibacterial composite materials of gelatin/astragalus gum/ZnO NPs nanoparticles (GEL/TGC/ZnO NPs) with different concentrations of ZnO NPs using zinc oxide nanoparticles (ZnO NPs) as antibacterial materials and gelatin and astragalus gum as film-forming substrates. Research has found that when the content of ZnO NPs is 5%, GEL/TGC/ZnO NPs composite materials have good antibacterial properties, with inhibition zone diameters of 14.8mm and 15.2mm for Staphylococcus aureus and Escherichia coli, respectively.
2.1.2 Copper oxide nanoparticles
Copper oxide nanoparticles (CuO NPs) have a loose and porous spherical morphology, and extremely low concentrations of CuO NPs have good antibacterial effects on various bacteria such as Escherichia coli, Bacillus subtilis, and Staphylococcus aureus. Its antibacterial mechanism is achieved by inhibiting the thiol group in bacterial enzymes, leading to bacterial inactivation. Through photocatalysis, hydrogen peroxide is produced, which enters the bacterial interior and causes bacterial death. Sathish et al. used copper oxide nanoparticles as antibacterial materials and prepared antibacterial nanofibers by adding polycaprolactone/gelatin electrospun nanofibers. Significantly increased the antibacterial performance of the material, with inhibition zone diameters of (51 ± 1.2) mm, (40 ± 1.7) mm, (31 ± 0.5) mm, and (30.5 ± 0.3) mm (including fiber diameter) for Staphylococcus aureus, multidrug-resistant Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli, respectively.
2.1.3 Other metal oxide nanoparticles
Researchers have developed antibacterial modified metal oxide nanoparticles and iron oxide nanoparticles (Fe) for gelatin materialsxOyNPs）、 Nickel oxide nanoparticles (NiO NPs), manganese dioxide nanoparticles (MnO)twoNPs and titanium dioxide nanoparticles (TiO)twoNPs）， It has good antibacterial performance against common pathogenic bacteria such as Escherichia coli and Staphylococcus aureus. Mahdieh et al. prepared NiO NPs and added them as antibacterial materials to a blend matrix of gelatin and chitosan to prepare antibacterial composite materials. When the NiO NPs content is 2%, the composite material exhibits good antibacterial performance, with inhibition zone diameters of 14.00mm and 11.00mm for Staphylococcus aureus and Escherichia coli, respectively.
2.2 Copper sulfide nanoparticles
The localized surface plasmon resonance absorption of near-infrared light by copper sulfide nanoparticles (CuS NPs) can convert near-infrared light energy into thermal energy, causing protein denaturation, DNA breakage, and other sterilization effects. Under light excitation, a large amount of reactive oxygen species (ROS) are generated, producing antibacterial effects. Under near-infrared light irradiation, both photothermal and photodynamic effects can coexist, synergistically inhibiting bacteria. As shown in Figure 3, the antibacterial composite material containing CuS NPs generates photothermal, photodynamic, and peroxidase like catalytic activities under the action of near-infrared laser, which synergistically destroy biofilm sterilization by generating hydrogen peroxide.
Figure 3 Schematic diagram of synergistic antibacterial mechanism
Hussain et al. prepared a blend film using fish skin gelatin and chickpea protein isolate (G-CP) as film-forming substrates, CuS NPs and black grass essential oil (MNEO) as antibacterial substances. In the antibacterial test results, when the mass fraction of CuS NPs was 0.03% and the mass fraction of MNEO was 0.5%, the antibacterial effect of the blend film was the best, with inhibition zone diameters of (27.11 ± 0.35) mm and (33.40 ± 0.28) mm for Staphylococcus aureus and Escherichia coli, respectively.
2.3 Silver Nanoparticles
Silver nanoparticles (Ag NPs) play a role in various fields such as wound care, biomedicine, textiles, and household appliances due to their unique physicochemical and biological antibacterial properties. Ag NPs can achieve bactericidal effects through direct contact with bacteria, so Ag NPs do not develop antibiotic resistance. In addition, Ag NPs can also release Ag+Penetrating bacterial cell walls to exert antibacterial activity.
Lin et al. used silver loaded nano titanium dioxide (TiO) as a carriertwo-Did Ag prepare fish gelatin as antibacterial material? Chitosan antibacterial composite film with added TiO at different concentrationstwo-Prepare composite films using Ag. Experiments have shown that when TiOtwo-When the Ag content is 0.5%, the antibacterial performance of the composite film is significantly improved, with antibacterial circle diameters of (20.6 ± 0.74) mm, (22.86 ± 1.45) mm, and (23.72 ± 1.25) mm for Escherichia coli, Staphylococcus aureus, and Botrytis cinerea, respectively; When TiOtwo-When the Ag content is 0.4%, the water vapor barrier ability of the composite film is the best, and when the content reaches 0.5%, the UV barrier ability of the composite film is greatly improved.
2.4 Carbon dots (CDs)
CDs are a new type of nano antibacterial material, which can be divided into four categories based on the different microstructures of carbon cores: graphene quantum dots (GQDs), carbon quantum dots (CQDs), carbon nanodots (CNDs), and carbonized polymer dots (CPDs). Among them, CDs have various advantages such as high antibacterial properties, wide sources, and good biocompatibility, and have broad prospects in fields such as food packaging, wound dressings, and textile fibers. Parveen et al. used arabic gum derived carbon dots (VNG-CD) as antibacterial materials to prepare nanocomposite films with chitosan (CH) and gelatin (GL). Research has found that when the mass fraction of VNG-CD is 5%, the semi inhibitory concentration values for Staphylococcus aureus, Escherichia coli, and Klebsiella pneumoniae are 19.9, 32.5, and 30.0 nM, respectively, indicating good antibacterial activity. Carbon dots, as antibacterial materials and gelatin based composite antibacterial functional materials, not only have excellent antibacterial properties, but also have various other excellent properties such as UV blocking, antioxidant, and low cell toxicity. With their unique antibacterial mechanism, they will not cause bacteria to develop drug resistance, and have considerable application prospects in the fields of food packaging and biomedicine. As a relatively new type of functional material, they have great potential for development.
3. Conclusion
Gelatin can be prepared into hydrogels, films, microcapsules, fibers and other forms of materials. Because of its excellent biodegradability and biocompatibility, it can be widely used in food packaging, biomedicine, drug delivery, dressings and other fields. Organic modified materials tend to use natural antibacterial agents to modify gelatin, which can not only reduce bacterial resistance, but some materials also have acid-base indicator ability to monitor the freshness of food. In inorganic modified materials, bacteria are inactivated through their multiple antibacterial mechanisms and are less likely to develop drug resistance. In the future, modified materials tend to be more natural and environmentally friendly. Natural animal and plant extracts and new multifunctional materials such as carbon dots will be research hotspots in modified materials. It is believed that in the near future, researchers will be able to find more suitable materials and methods to prepare materials with better antibacterial properties, which will further promote food safety and the pharmaceutical and medical industries.
First author:
Zhou Wei (2002-), male, undergraduate, engaged in research on environmentally friendly materials, 2908201044@qq.com
Corresponding author:
Chen Jie (1985-), female, associate professor, engaged in research on cellulose functional materials, environmentally friendly materials, and biodegradable materials, chenjie6261328@126.com
Luo Xiongfang (1991-), female, lecturer, engaged in research on functional materials and clean dyeing and finishing technology, Lxf4030@163.com
DOI:10.19491/j.issn.1001-9278.2025.
two point zero two one
Quoting this article:
Zhou Wei, Chen Jie, Si Zhihao, etc Research progress on antibacterial functionalized gelatin based composite materials [J]. China Plastics, 2025, 39 (02): 112-117
ZHOU Wei,CHEN Jie,SI Zhihao,et al.Research progress in antibacterial functional gelatin matrix composites[J].CHINA PLASTICS,2025,39(02):112-117.
Source: China Plastics, Volume 39, Issue 2, 2025
