Gelatin Films Research Articles

Ultra-sensitive air pressure sensor based on gelatin diaphragm-based Fabry-Peroy interferometers and Vernier effect

We proposed and experimentally demonstrated a gelatin diaphragm-based Fabry-Perot interferometer (FPI) structure ultra-sensitive fiber optic air pressure sensor. The Fabry-Perot (F–P) cavity of the sensing probe FPI1 is made of gelatin diaphragm, with a thickness of approximately 0.8 μm and the probe length of approximately 136 μm. The air pressure sensitivity of the probe obtained in the experiment is as high as 334 nm/MPa. In order to further improve the sensitivity of the probe, we fabricated an FPI2 with an air F–P cavity that is approximately the length of the FPI1 cavity, and then paralleled FPI2 with FPI1 to generate a Vernier effect. The average sensitivity of the Vernier probe obtained in the experiment reached −2650 nm/MPa, which magnified the sensitivity of a single FPI1 by about 7.9 times. The temperature cross-sensitivity is only 3.6 kPa/°C. This proposed air pressure sensor has the advantages of ultra-high sensitivity, simple manufacturing, low cost, good repeatability and stability, and has broad application prospects in high sensitivity pressure and acoustic detection.

Thymol as a Component of Chitosan Systems—Several New Applications in Medicine: A Comprehensive Review

Thymol, a plant-derived monoterpene phenol known for its broad biological activity, has often been incorporated into chitosan-based biomaterials to enhance therapeutic efficacy. Using the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines, we conducted a systematic literature review from 2018 to 2023, focusing on the biomedical implications of thymol-loaded chitosan systems. A review of databases, including PubMed, Scopus, and Web of Science was conducted using specific keywords and search criteria. Of the 90 articles, 12 were selected for the review. Thymol-loaded chitosan-based nanogels (TLCBS) showed improved antimicrobial properties, especially against multidrug-resistant bacterial antagonists. Innovations such as bipolymer nanocarriers and thymol impregnated with photosensitive chitosan micelles offer advanced bactericidal strategies and show potential for bone tissue regeneration and wound healing. The incorporation of thymol also improved drug delivery efficiency and biomechanical strength, especially when combined with poly(dimethylsiloxane) in chitosan–gelatin films. Thymol–chitosan combinations have also shown promising applications in oral delivery and periodontal treatment. This review highlights the synergy between thymol and chitosan in these products, which greatly enhances their therapeutic efficacy and highlights the novel use of essential oil components. It also highlights the novelty of the studies conducted, as well as their limitations and possible directions for the development of integrated substances of plant and animal origin in modern and advanced medical applications.

Development of films based on chitosan, gelatin and collagen extracted from bocachico scales (Prochilodus magdalenae)

Biodegradable biopolymers from species of the animal kingdom or their byproducts are sustainable as ecological materials due to their abundant supply and compatibility with the environment. The research aims to obtain a biodegradable active material from chitosan, gelatin, and collagen from bocachico scales (Prochilodus magdalenae). Regarding the methodology, films were developed from gelatin, chitosan, and collagen from bocachico scales (Prochilodus magdalenae) at different concentrations using glycerol as a plasticizer and citric acid as a cross-linker. The films were obtained with the hydrated mass processed by compression molding and characterized according to humidity, water solubility, contact angle, mechanical properties, and structural properties. The results of the films showed a hydrophobic characteristic. First, the chitosan-collagen (CS/CO) films showed a yellowish color, while the gelatin-collagen (Gel/CO) films were transparent and less soluble than the gelatin-collagen (Gel/CO) films. Concerning mechanical properties, gelatin films showed higher stiffness and tensile strength than chitosan films. Furthermore, in the morphological analysis, more homogeneous chitosan films were obtained by increasing the concentration of citric acid. In general, chitosan, gelatin, and collagen extracted from the scales of the bocachico (Prochilodus magdalenae) are an alternative in the application of films in the food industry.

Microencapsulation of curcumin by complex coacervation of lactoferrin and carboxymethyl tara gum for incorporation into edible films

Curcumin is a natural bioactive agent found in turmeric (Curcuma longa) with many health benefits, but with susceptibility to alkaline conditions, light, oxidation and heat. The present research aimed microencapsulate curcumin by complex coacervation using lactoferrin (LF) and carboxymethyl tara gum (CMTG) for application in edible films. The study of wall material formation was carried out by phase diagram, zeta potential and isothermal titration calorimetry. Curcumin was encapsulated by complex coacervation using different core-to-wall ratios and total biopolymer concentration. Finally, the microcapsules were used for the fabrication of edible gelatin-based films. The results showed that LF and CMTG could form complexes at pH 4.5 by electrostatic attraction with high affinity and optimum encapsulation efficiency of curcumin (74.78 %). The microcapsules protected curcumin during the oral and gastric phases with an average release in the intestinal phase of 81.81 %. After in vitro gastrointestinal digestion, the bioaccessibility of encapsulated curcumin was approximately 67 %. Curcumin microcapsules were added to edible gelatin films, which resulted in reduced light transmission and presence of antioxidant activity (FRAP and DPPH·+). The films containing microcapsules had their mechanical properties preserved. Therefore, curcumin-containing microcapsules formed by complex coacervation of LF/CMTG can be used in the production of edible films with high functional properties.

High strength and water tolerance fish gelatin-xanthan gum acid-induced electrostatic film by melt extrusion method

Gelatin is a biodegradable natural polymer that can be utilized in preparing edible films, and its films tend to have defects in mechanical properties and water tolerance, limiting their application. In this study, we combined the acid-induced electrostatic system to prepare the gelatin extruded film, and the relevant mechanisms were explored. The films' thermal stability, microstructure, mechanical properties, water tolerance, and degradability were also evaluated. Films were prepared by adding different levels of xanthan gum and malic acid to the film substrate. Compared to FG-M-0%, FG-MX-0.5% showed a 120.61% increase in tensile strength, a 9.79 °C and a 16.72 °C increase in melting temperature and glass transition temperature, respectively, the acidified FG-MX group as a whole had a higher water contact angle and lower swelling rate. FTIR and XRD confirmed that acid induction enhanced the electrostatic interactions and hydrogen bonding between gelatin-xanthan gum. The results showed that the melt-extruded gelatin film could also maintain the acid-induced electrostatic effect well, with stronger physical properties and better water tolerance, and were conducive to the efficient preparation of gelatin films with desirable properties and the expansion of their range of applications.

Effect of electrostatic repulsion on barrier properties and thermal performance of gelatin films by carboxymethyl starch, and application in food cooking

Carboxymethyl starch (CST) was introduced to improve gelatin films and its practical application as edible high-performance films for food packaging and cooking was also investigated. The gelatin films modified by carboxymethyl starch exhibited the transparent appearance, tensile strength, barrier properties (oxygen, water vapor and UV light), and thermal performance (TGA, thermal shrinkage and heat-sealing strength). Resulting from the effect of electrostatic interaction modes on the properties of films, electrostatic repulsion could surpass electrostatic attraction in improving the tensile strength, oxygen barrier property and thermal stability of the films probably due to extensive physical entanglement without aggregation. Analysis of FTIR, zeta potential, interfacial dilatational rheology, shear rheological properties, XRD, Raman, SEM and AFM suggested that hydrogen bonding and electrostatic repulsion contributed to the excellent performance. The packaged food could also be cooked with the prepared film for porridge; and the film slightly influenced the shear rheological properties of porridge and imposed little effect on the odors (Electronic-Nose) of porridge. Hence, the gelatin films modified by carboxymethyl starch could potentially work as the edible inner packaging or the edible quantitative packaging for food, offer convenience for consumers, reduce the packaging waste and avoid an extra burden on environment.

Heavy metal ion uptake using biodegradable polymeric film

This study investigates the potential of gelatin films as a biodegradable material for food preservation and heavy metal ion removal. Gelatin, a biodegradable protein derived from animal collagen, was dissolved in distilled water to form a solution and casted to form films. The films were evaluated for their swelling behavior, solubility in food, moisture content, thickness, and biodegradability. The results showed that gelatin films were completely soluble in water within 3 hours, with a water solubility of 29 ± 1.6%. The films showed UV-visible light absorbance ranging from 280 to 480 nm with maximum absorbance at 420 nm. The films were also found to have a high potential for heavy metal ion removal, specifically for copper (II) and zinc (II) ions. The films were able to effectively remove these ions from aqueous solutions under acidic conditions, with removal efficiencies of 99.3% and 97.3%, respectively. The findings suggest that gelatin films could be a promising material for sustainable food packaging and for removing heavy metals from wastewater.

Enhanced barrier and antioxidant properties of gelatin films by structural-colored bioactive materials for food packaging

Neoteric functional gelatin films were fabricated based on structural-colored bioactive materials and applied in practical food applications. The bioactive materials could induce the excellent shear-thinning structure and benefit the spreading, leveling and thus the film forming process. From FTIR, XRD, zeta potential, SEM and AFM, the hydrogen bonding and electrostatic interaction between bioactive materials (monascus red, phycocyanin, and safflower yellow) and biopolymers, could cause the compact network structure and improve the performance of final films compared to the films without bioactive materials, including chromatic appearance, mechanical characteristics (increasing tensile strength by 625.27%, 184.10% and 296.00%, respectively), barrier properties (decreasing oxygen transmittance rates by 96.27%, 85.81% and 94.58%; and increasing light opacity by 216.56%, 54.91% and 174.04%, respectively), and antioxidant activity (increasing ABTS free radical scavenging property by 92.24%, 110.12% and 111.70%, respectively). During blueberry preservation, the functional films could effectively delay the weight loss and hardness reduction. When packaging food ingredients, functional films could be cooked together with rice and oats for obtaining excellent-looking porridge with special masticatory sensation, and have little effect on the odors (electronic-nose). Therefore, gelatin films incorporated with bioactive materials could potentially act as fresh-keeping packaging or direct eating/cooking packaging, and exhibit environmental-protective merits and recyclability, holding promises as an alternative for plastic packaging.

Phage Lytic Protein CHAPSH3b Encapsulated in Niosomes and Gelatine Films.

Antimicrobial resistance (AMR) has emerged as a global health challenge, sparking worldwide interest in exploring the antimicrobial potential of natural compounds as an alternative to conventional antibiotics. In recent years, one area of focus has been the utilization of bacteriophages and their derivative proteins. Specifically, phage lytic proteins, or endolysins, are specialized enzymes that induce bacterial cell lysis and can be efficiently produced and purified following overexpression in bacteria. Nonetheless, a significant limitation of these proteins is their vulnerability to certain environmental conditions, which may impair their effectiveness. Encapsulating endolysins in vesicles could mitigate this issue by providing added protection to the proteins, enabling controlled release, and enhancing their stability, particularly at temperatures around 4 °C. In this work, the chimeric lytic protein CHAPSH3b was encapsulated within non-ionic surfactant-based vesicles (niosomes) created using the thin film hydrating method (TFH). These protein-loaded niosomes were then characterized, revealing sizes in the range of 30-80 nm, zeta potentials between 30 and 50 mV, and an encapsulation efficiency (EE) of 50-60%. Additionally, with the objective of exploring their potential application in the food industry, these endolysin-loaded niosomes were incorporated into gelatine films. This was carried out to evaluate their stability and antimicrobial efficacy against Staphylococcus aureus.

Precise patterning of gold nanoparticle gratings on gelatin films

A method (based on holographic lithography, dry etching and temperature annealing) to fabricate gold nanoparticles in gelatin films and pattern them into gratings with periods down to 200 nm, controlling the size and particle distribution.

A triboelectric nanogenerator based on CNC/gelatin for running and jumping training monitoring

In this work, we proposed a triboelectric nanogenerator (TENG) based on cellulose nanocrystal (CNC)/gelatin composite film (CG-TENG) to monitor the posture and movements of athletes during jumping training. The triboelectric layers comprise a polytetrafluoroethylene film (which carries a negative charge) and a CNC/gelatin composite film (manifesting a positive charge). The CNC is derived from recycled wasted boxes using the traditional sulfuric acid hydrolysis method and is incorporated into the gelatin film as a nanoscale additive. By utilizing an external load resistance measuring 20 MΩ, it is possible to attain an all-time high instantaneous power of 583 µW. The electrical output of the CG-TENG demonstrates notable stability and endurance, as it maintains a consistent pattern during a duration of more than 30 000 cycles. By capitalizing on sustainable and green materials, the CG-TENG paves the way for innovative sports monitoring solutions, amplifying the potential for human physiological signal tracking.

The effects of plasticizers on the mechanical properties and chemical composition of a gelatin biopolymer

Every day, oil-based plastics are manufactured, consumed, and discarded without a second thought. To combat plastic pollution, we decided to investigate gelatin bioplastics. We analysed the effects of the increasing concentration of polyethylene glycol (PEG) and glycerol plasticizers on the mechanical properties and chemical composition of the gelatin bioplastic matrix through a series of experiments. In the first experiment, we determined their tensile strength (TS) and the elongation at break (EAB) through tensile testing. We hypothesised that increasing concentrations of the plasticizers would decrease TS and increase EAB. In the second experiment, we studied their O–H bonds by Fourier-transform infrared spectroscopy analysis (FTIR). Our second hypothesis maintained that the number of O–H bonds would increase because plasticizers disrupt polymer-polymer and polymer-water hydrogen bonds. For the mechanical properties, we observed that when the concentration of PEG and glycerol plasticizers increased so too did EAB. The rising concentrations of glycerol led to a decreasing trend with TS, whereas PEG showed an increasing trend. The FTIR spectrum revealed that a high abundance of O–H bonds was present at the strong and broad absorption peak of 3400 cm-1, with the pure gelatin films having the highest absorption, followed by glycerol-plasticized films and PEG-plasticized films having the least absorption. We concluded that 3% w/v PEG film outperformed other PEG films and 3% w/v glycerol films. The cytotoxicity results showed that all films had a cell viability above the threshold of 75% and hence food-safe.

Enhanced properties of gelatin films incorporated with TiO2-loaded reduced graphene oxide aerogel microspheres for active food packaging applications

The synergistic effect of graphene sheets and titanium dioxide nanoparticles (TiO2) hybrid fillers can improve the antibacterial, mechanical, and barrier properties of gelatin (GL), making it more suitable to be used in the food packaging application. However, the uneven dispersion and aggregation of the hybrid fillers restrict its performance for further application. In order to achieve the above superior properties, reduced graphene oxide aerogel microspheres (rGOAMs) loaded with TiO2 (rGOAMs@TiO2) were successfully prepared using one-step hydrothermal process by reducing titanium sulfate into TiO2 on the framework of rGOAMs, followed by effective dispersion in the GL matrix to form nanocomposites (rGOAMs@TiO2/GL) through simultaneous ultrasonication and mechanical stirring, as well as an ultrasonic cell grinder process. Incorporating a mere 0.8 wt% of rGOAMs@TiO2 effectively improved the mechanical, antibacterial, UV light barrier, thermal stability, hydrophobicity, and water vapor barrier properties of the GL. Compared with the composites made of rGOAMs, TiO2, and GL (rGOAMs/TiO2/GL), rGOAMs@TiO2/GL composites showed stronger filler-matrix interactions, better filler dispersion, and lower TiO2 particle aggregation, suggesting superiority compared to rGOAMs/TiO2/GL composites at the same filler content. This innovative method of mixing GL with rGOAMs@TiO2 holds great promise for enhancing the suitability of GL in active food packaging applications.

Water state, thermal transition behavior and structure of hydrated gelatin films.

The state of water, thermal transition behaviors, molecular interactions, crystalline structure, and mechanical performance of hydrated gelatin films were studied by differential scanning calorimetry (DSC), infrared spectroscopy (FTIR), X-ray diffraction, and universal testing instruments. The DSC results showed that with increase of the water content, two types of water, including unfreezable bound water and freezable water, appeared in turn. Below a critical water content of 30%, the glass transition temperature (Tg) of the hydrated gelatin films decreased notably with an increase in water content, which leveled off at water content higher than this threshold. This observation suggests that only the unfreezable water exhibits a plasticizing effect. In addition, the melting temperature (Tm) of hydrated gelatin films decreased continuously with an increase in water content, whereas the melting enthalpy showed a non-monotonic dependence on hydration level. Structural analysis showed that at medium hydration levels up to 13.4% water content, the unfreezable water facilitated the formation of additional triple helices, confirmed by DSC results. Spectral data revealed that the -OH groups of unfreezable water molecules interacted with the -NH groups of the protein via hydrogen bonds. Moreover, the mechanical properties of the hydrated gelatin films were sensitive to their hydration level, and the tensile strength was dominated by the helix content of the protein films. These results show the feasibility of using hydration to regulate the microstructure and properties of biopolymers.

Onion peel extract as milk freshness indicator in biopolymer-based intelligent packaging films

Intelligent food packaging is used to monitor quality / freshness of packaged food product, and to communicate them to consumers. Natural color-based pH indicators can be effective agents in biopolymer-based intelligent packaging systems. In this study, gelatin and sodium alginate-based sustainable intelligent packaging films incorporated with onion peel extract (OPE) as the pH indicator were fabricated for monitoring and indicating milk freshness. Effects of incorporation of OPE on moisture content, solubility, swelling, transparency, antioxidant activity, and total phenolic contents of the fabricated films were also evaluated. The developed films were characterized using Fourier transform infrared (FTIR), field emission scanning electron microscopy (FESEM), and their color changes due to pH sensitivity were measured. The fabricated intelligent films / labels were tested against milk at different pH of 6.5, 6, 5.5, 5, 4.5, 4, and 3.5, and the discernible color changes were measured. The developed intelligent films / labels showed significant change in their color with change in pH of the milk samples. Thus, the films can be used as sustainable alternative, as freshness indicator for packaged milk.

Buccal delivery system of active pharmaceutical ingredients-ionic liquid (API-IL): Effects of API-IL loading and gelatin film concentration

Ionic liquid (IL) salt of active pharmaceutical ingredient (API) represents a promising formulation strategy to address low drug solubility and polymorphism prevalent in API solid crystals. The present work developed for the first time a buccal delivery system of API-IL via fast-dissolving API-IL-loaded gelatin films. Imidazolium-based ibuprofen salt was used as the model API-IL. The effects of API-IL loading and gelatin concentration on the film’s (i) mechanical strength, (ii) inter-batch uniformity in the films’ API payload, weight, and thickness, (iii) thermal stability, (iv) API dissolution and solubility enhancement were investigated. The plasticizer role of API-IL was evident, where minimum 30 wt% API-IL loading was needed to produce flexible yet mechanically-strong films. Lower API-IL loading produced brittle films due to insufficient plasticization facilitated by hydrogen bond interactions between API-IL and gelatin. Gelatin concentration influenced films’ mechanical strength, weight/thickness, and API dissolution rate. Depending on the API-IL loading and gelatin concentration, films with API payload (7–30 mg/cm2), thickness (300–900 µm), and weight (20–110 mg/cm2) were produced at nearly 100% efficiency and high inter-batch uniformity. API-IL existed as amorphous liquid in the film exhibiting fast API dissolution (100% in 15 min) and high kinetic solubility (8 times thermodynamic solubility) in simulated saliva fluid.

Optimization of an edible film formulation by incorporating carrageenan and red wine lees into fish gelatin film matrix

The study aimed to use response surface methodology (RSM) to create and understand a novel edible film made from fish gelatin (FG). This film includes wine lees (WL) and carrageenan (CAR). The concentrations of WL (0, 1, 2, and 3 %) and CAR (0, 1, and 3 %) were considered independent variables. The process variable combinations for the optimal response functions were 1.926 % WL and 3 % CAR, forming soft and rigid films with low tensile strength (TS) and high elongation at break (EAB%). Based on the evaluation of each response, FG film had the highest TS value, FG/CAR(3 %) film had the maximum EAB, and FG/WL (3 %)/CAR (3 %) film had the lowest vapor permeability (WVP) and the highest opacity (OP). The incorporation of WL considerably improved the functional properties of these films, enabling strong antioxidant activity and high phenolic content. Characterization of the films with analytical techniques: Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD) analysis demonstrated a considerable interaction between WL and FG, indicating a high level of compatibility between the two substances. Our data suggest that the formulation of edible films can be adjusted to fit the specific requirements of the design.

Gelatin films reinforced by tannin-nanocellulose microgel with improved mechanical and barrier properties for sustainable active food packaging

In this study, reactive tannin-nanocellulose (TANC) microgels, prepared using dialdehyde nanocellulose and tannin through the condensation reaction, were incorporated into gelatin matrix to fabricate GE-TANC films for the potential application as active food packaging materials. AFM, FT-IR, XRD, and TG analysis were employed for characterization of TANCs and the composite films. AFM images and FT-IR analysis confirmed the successful crosslinking of nanocellulose with tannin. Their surface hydrophilicity, UV-blocking capability, antioxidant activity and mechanical properties were measured to investigate the impact of TANC microgels on the film properties. The tannin-containing films displayed excellent antioxidant and UV-blocking properties, maximally scavenging 79% of DPPH free radicals and absorbing 98% of ultraviolet light. The surface hydrophilicity, water vapor transmission rate (WVTR) and water solubility of the composite films decreased compared to those of the neat gelatin film, resulting from the formation of more chemical and physical crosslinkings within the film. The tensile strength tripled from 40 MPa to 108 MPa, and the elongation at break increased from 3.87% to 6.28% with only 5% of TANC2. The GE-TANC films in this work demonstrated high mechanical properties, oxidation and UV resistance, and thus have a prospective application as the sustainable active food packaging materials.

Fabrication of nanocomposite gelatin-based film by the pickering emulsion containing nanoparticles of chitin

The effect of different amounts of pickering emulsion on the physical, thermal, and structural properties of gelatin nanocomposite film containing chitin nanocrystals (NCs) was examined in the present study. Pickering emulsions were produced using chitin NCs with 0.7, 1, and 1.3% concentrations, and their characteristics were investigated. The physical and thermal stability and zeta potential of the emulsion containing 1.3% nanocrystals were higher than those of the other emulsions; therefore, it was chosen to prepare the films. Nanocomposite films were produced with 10, 20, and 30% of pickering emulsion, and their physical, thermal, and structural characteristics were studied. The differential scanning calorimetry (DSC) thermograph showed good thermal stability of emulsion films compared to pure gelatin film. Fourier transform infrared spectroscopy (FT-IR) results confirmed the excellent compatibility of nanoparticles with gelatin film. The barrier property of emulsion films was better than that of pure gelatin film. Therefore, about 10% emulsion containing 1.3% nanoparticles in nanocomposite films can create biodegradable biopolymers for food packaging.

Thin-core fiber-based Mach-Zehnder interferometer sensor for monitoring temperature, pressure, and humidity

A Mach-Zehnder interferometer (MZI) sensor based on thin-core fiber (TCF) is proposed. Sensitive materials such as polydimethylsiloxane (PDMS) or gelatin are coated on the surfaces of MZIs to achieve temperature, pressure, and humidity measurements. MZI is composed of single mode fiber (SMF), TCF, and multimode fiber (MMF) spliced together to form a “SMF-MMF-TCF-MMF-SMF” structure. The core/cladding diameters of TCF are 3.8 µm and 80 µm respectively. When three types of optical fibers with different core diameters are cascaded together, many cladding modes are excited to form MZI. Firstly, two similar MZI structures were fabricated designated by MZI1 and MZI2. In order to improve the sensitivity and mechanical strength, a layer of PDMS film was coated on the TCF surface of MZI1. Then, a layer of gelatin film is covered on the TCF surface of MZI2. PDMS has the high thermal expansion coefficient, thermal optical coefficient, and elasticity, and gelatin has good humidity sensitivity properties. The experimental results showed that the temperature and pressure sensitivity of MZI1 coated with PDMS reached −340 pm/°C and −14.3 nm/MPa, respectively, while the humidity sensitivity of MZI2 coated with gelatin reached −112.57 pm/% RH. When a fiber Bragg grating is cascaded with the MZI1, the sensor can achieve simultaneous measurement of temperature and pressure, eliminating crosstalk. The proposed sensor has an extremely simple structure and manufacturing method, which only involves the splicing of optical fiber and the coating by the film. In addition, the proposed sensor has a robust structure, good repeatability and stability, and high sensitivity, which has broad application prospects.