Gelatin Coatings Research Articles

Development of bioactive glass based scaffolds for controlled antibiotic release in bone tissue engineering via biodegradable polymer layered coating.

Highly porous 45S5 Bioglass(®)-based scaffolds coated with two polymer layers were fabricated to serve as a multifunctional device with controlled drug release capability for bone regeneration applications. An interior poly(d,l-lactide)/poly(ethylene glycol)-(polypropylene glycol)-poly(ethylene glycol) triblock copolymer (Pluronic P123) coating improved the mechanical stability of Bioglass-based scaffolds, while an exterior natural polymer (alginate or gelatin) coating served as an antibiotic drug carrier. The results showed improved mechanical properties of Bioglass-based scaffolds by the bilayer polymer coating. In addition, hydrochloride tetracycline loaded in either alginate or gelatin coatings was released rapidly at the initial stage (∼1 h), while the released rate subsequently decreased and was sustained for 14 days in phosphate buffered saline. Therefore, these layered polymer coated scaffolds exhibit attractive characteristics in terms of improved mechanical properties and controlled drug release, simultaneously with the added advantage that the drug release rate is decoupled from the intrinsic scaffold Bioglass degradation mechanism. The layered polymer coated scaffolds are of interest for drug-delivery enhanced bone regeneration applications.

Effect of a gelatin-based edible coating containing cellulose nanocrystals (CNC) on the quality and nutrient retention of fresh strawberries during storage

Strawberry is a non-climacteric fruit with a very short postharvest shelf-life. Loss of quality in this fruit is mostly due to its relatively high metabolic activity and sensitivity to fungal decay, meanly grey mold (Botrytis cinerea). In this study, the ability of gelatin coatings containing cellulose nanocrystals (CNC) to extend the shelf-life of strawberry fruit (Fragaria ananassa) over 8 days were studied. The filmogenic solution was obtained by the hydration of 5 g of gelatin (GEL) in 100 mL of distillated water containing different amounts of CNC dispersion (10 mg CNC/g of GEL or 50 mg of CNC/g of GEL) for 1 hour at room temperature. After this period, the solution was heated to 70 °C and maintained at this temperature for 10 minutes. The plasticizer (glycerol) (10g/100g of the GEL) was then added with constant, gentle stirring in order to avoid forming air bubbles and also to avoid gelatin denaturation until complete homogenization. Strawberries (purchased at the local market) were immersed in the filmogenic solution for 1 minute and after coated were dried at 15 °C by 24 hours. The strawberries were then kept under refrigeration and characterized in terms of their properties (weight loss, ascorbic acid content, titratable acidity, water content). The results have shown that samples covered with GEL/CNC had a significant improvement in its shelf- life. For instance, for the control sample (without coating) the weight loss after 8 days of storage was around 65%, while covered samples loss in the range of 31-36%. Edible coating was also effective in the retention of ascorbic acid (AA) in the strawberries, while control sample presented a fast decay in the AA content, covered samples showed a slow decay in the AA concentration. Moreover, the use of GEL/CNC edible coating had an antimicrobial effect in the fruits.

Effects of a composite chitosan–gelatin edible coating on postharvest quality and storability of red bell peppers

For the first time, a composite chitosan–gelatin (CH–GL) coating was applied to peppers and its effects on fruit quality and storability were examined. Pure chitosan (CH) and gelatin (GL) coatings were studied for comparison. The CH coating inhibited microbial spoilage and prolonged the possible storage period. The GL coating contributed to fruit firmness, but did not allow for prolonged storage. The composite CH–GL coating was associated with a two-fold decrease in microbial decay, significantly (p≤0.05) enhanced fruit texture and prolonged the possible period of cold storage up to 21 days and fruit shelf-life up to 14 days, without affecting the respiration or nutritional content of the fruit.

Gelatin functionalised porous titanium alloy implants for orthopaedic applications

In the present work, we studied the immobilisation of the biopolymer gelatin onto the surface of three dimensional (3D) regular Ti6Al4V porous implants to improve their surface bio-activity. The successful immobilisation of the gelatin coating was made possible by a polydopamine interlayer, a polymer coating inspired by the adhesive nature of mussels. The presence of both coatings was first optimised on two dimensional titanium (2D Ti) substrates and confirmed by different techniques including X-ray photelectron spectroscopy, contact angle measurements, atomic force microscopy and fluorescence microscopy. Results showed homogeneous coatings that are stable for at least 24h in phosphate buffer at 37°C. In a next step, the coating procedure was successfully transferred to 3D Ti6Al4V porous implants, which indicates the versatility of the applied coating procedure with regard to complex surface morphologies. Furthermore, the bio-activity of these stable gelatin coatings was enhanced by applying a third and final coating using the cell-attractive protein fibronectin. The reproducible immobilisation process allowed for a controlled biomolecule presentation to the surrounding tissue. This newly developed coating procedure outperformed the previously reported silanisation procedure for immobilising gelatin. In vitro cell adhesion and culture studies with human periosteum-derived cells showed that the investigated coatings did not compromise the biocompatible nature of Ti6Al4V porous implants, but no distinct biological differences between the coatings were found.

Influence of zein and gelatin coatings on the postharvest quality and shelf life extension of mango (Mangifera indicaL.)

Introduction . Mango is the most economically important and nutritionally rich tropical fruit; it has high commercial value but a highly perishable nature; its sensitivity to postharvest diseases and physical injury limits its successful marketing. Postharvest losses in fruits are a serious problem because of rapid deterioration during handling, transport and storage. Edible films and coatings can be potentially used as an elective preservation technique to extend the shelf life of fruits. Materials and methods . The influence of zein and gelatin coatings on the physicochemical characteristics, softening and antioxidative enzyme activities of mango fruits stored at (32 ± 1) °C were evaluated at regular intervals of their storage period and compared with mango without coatings (control). Results and discussion . Zein and gelatin coatings seemed to have a beneficial impact on delaying the changes in weight loss, soluble solids, titratable acidity, pH, sugar content and total carotenoids. Zein and gelatin coatings resulted in the highest retention of ascorbic acid and phenolic content as compared with that of control. Zein and gelatin coatings delayed the ripening of mango fruit by suppressing the activity of softening enzymes such as polygalacturonase, pectin methyl esterase, cellulase and β-galactosidase. Zein 5% and gelatin 10% coatings maintained the highest induction of defense-related peroxidase enzymes, followed by gelatin 5% and zein 10% coatings. Conclusion . The application of zein 5% and gelatin 10% coatings could be used in delaying the ripening, maintaining the quality attributes and extending the shelf life of mango fruit during storage.

Osteogenetic property of a biodegradable three-dimensional macroporous hydrogel coating on titanium implants fabricated via EPD

The potential for a successful integration of implants with surrounding tissue may be jeopardized in a number of compromised conditions. Biochemical surface modification is one of the choices to extend the spectrum of indications. We have previously successfully fabricated chitosan–gelatin (CS/G) coatings on a titanium surface via electrophoretic deposition, which may be promising candidates for further loading of functional agents. In this study, we have identified the microstructure, physicochemical properties and biological performance of CS/G coatings in vitro and in vivo. The in vitro degradation test indicated that CS/G coatings in the presence of lysozyme showed a significant weight loss after 28 days. The results of the cell culture exhibited that CS/G coatings could sustain MC3T3-E1 cell attachment, proliferation and migration. In vivo osteogenetic behavior evaluated by Micro-CT and histomorphometrical analysis revealed significant new bone formation around CS/G implants at 8 and 12 weeks, compared to sandblasted/acid-etched implants. Moreover, histological evaluation suggested the majority of CS/G coatings were degraded at 12 weeks. Therefore, we have concluded that the three-dimensional porous structure of scaffold-like CS/G coatings may facilitate osteogenesis and that such coatings can be biodegraded in the early bone healing process.

Humidity Sensing Using Gelatin and Cobalt Chloride Coating on Indium Tin Oxide-Coated Long-Period Grating

In this article, humidity sensing using gelatin and cobalt chloride on indium tin oxide coated long-period gratings was proposed and demonstrated. First, a thin overlay of indium tin oxide was deposited on a long-period grating by using a simple dip coating methodology. Similarly, a combination of gelatin and cobalt chloride was deposited onto the indium tin oxide layer. A field emission scanning electron microscope provided detailed evidence of the attachment of amalgamation on long-period gratings. The designed sensor showed a significant shift in the resonance wavelength when the relative humidity varied from 40% to 95%, with a sensitivity of 0.12 nm/% relative humidity and an accuracy of 98.45%.

Characterization of unprocessed historic platinum photographic papers by Raman, FTIR and XRF

Five unprocessed historic platinum photographic papers were characterized by a combination of Raman, FTIR and XRF spectroscopies to gain insight into their manufacturing processes and obtain information that can help identify the use of similar papers in works of art in a non-invasive manner. The analysis of one of these papers, ‘Japine Platinotype for Sepia Tones,’ showed a sensitized surface layer in the recto consistent with the use of a parchmentization process of the paper substrate, and that the verso presents a slightly modified surface. Raman and FTIR measurements revealed that this surface layer in Japine is composed mainly of amorphous cellulose. No gelatin or other surface coatings were found to be present in Japine. In the rest of the papers studied, the sensitizer was found to have been applied directly onto the paper fibers and no gelatin or gums were observed as sizings. Relatively larger amounts of mercury were detected in Japine, confirming the use of a Hg salt in a sepia-type platinum paper. The combined use of Raman and XRF provides information that can help discriminate platinum photographic processes involving parchmentization in works of art in a non-invasive manner.

Essential oils of thyme and Rosemary in the control of Listeria monocytogenes in raw beef

This study was developed in order to evaluate two alternatives for the control of Listeria monocytogenes in raw bovine meat pieces, both based on the use of Thymus vulgaris and Rosmarinus officinalis essential oils (EOs). The antilisterial activity of different concentrations of the EOs was tested in vitro using agar dilution and disk volatilization techniques. In addition, L. monocytogenes was inoculated in meat pieces, which were submerged in edible gelatin coatings containing 2% (v/v) EOs or submitted to the vapor of EOs (0.74 μL.cm(-3)). L. monocytogenes was quantified after one, 48 and 96 hours of storage (7 °C). In the in vitro tests, the EO of T. vulgaris presented higher activity. The two options used (edible gelatin coating and vapor activity), in spite of exercising effects with differentiated behaviors, presented antibacterial activity against L. monocytogenes inoculated in raw bovine meat (p < 0.05). Greatest antibacterial activity were obtained in the experiment that used edible coatings containing EOs, at 48 hours of storage reductions in bacterial counts between 1.09 and 1.25 Log CFU.g(-1) were obtained. In the vapor effect experiment, the EO of T. vulgaris caused the highest reduction in the population of bacteria inoculated in raw bovine meat (p < 0.05), 0.40 Log CFU.g(-1) at 96 hours of storage. This study supplied important information regarding new and promising natural alternatives, based on the concept of active packaging, for the control of L. monocytogenes in the meat industry.

Controlled Release of Fluidized Bed-Coated Menthol Powder with a Gelatin Coating

We estimated the release properties of fluidized bed-coated menthol powder by static headspace analysis and by relating the release properties and the properties of the coating. Powder was spray-dried onto different coating materials such as gelatin, an oil-gelatin emulsion, modified starch, and Aquacoat® ECD in a fluidized bed system, and then submerged in water at 37°C with a shearing force. The release properties of encapsulated menthol powder were estimated over 15 min compared with spray-dried powder. The microencapsulation efficiency of menthol powders was determined, as well as the density, surface tension, viscosity, and powder contact angle of coating materials. The gelatin emulsion was found to be a potential coating material for controlling menthol release from the coating powder and high microencapsulation efficiency (90.44%) achieved; 60% of the menthol powder was released after 11 min. These results indicate that the solubility and integrity of the coating is important to the success of the fluidized bed-coating process for controlled release of flavor from this degradation-activated release system.

Selective gene delivery to cancer cells secreting matrix metalloproteinases using a gelatin/polyethylenimine/DNA complex

We developed a gene delivery strategy targeting metastatic tumors by exploiting the specific matrix metalloproteinases (MMPs) secreting properties of metastatic tumor cells. A ternary polyplex has been formed by coating polyethylenimine/DNA (PD) complex with an excessive amount of negatively charged gelatin B (GPDB). We show that GPD-B’s gene delivery activity could be targeted to cancer cells via the MMP-mediated proteolytic process, while GPD-A, made from positively charged gelatin A, was not successful in exhibiting such activity. The 1,10-Phenanthroline, an MMP2 inhibitor, abrogated the MMP-dependent transfection activity of GPD-B. GPD-B carried much less positive surface charges than PD, and thus exhibited significantly reduced interactions with erythrocytes. However, MMP2 elevated the positiveness in GPDB’s surface charge and, thus, its interaction with erythrocytes. These results suggest that the anionic gelatin coating may confer improved stabilities on GPD-B in the surrounding medium, while MMP2-mediated disintegration of the gelatin coat enhances the gene delivery to metastatic cancer cells via increasing the likelihood of local chargemediated interactions between the polyplex and cancer cell membrane.

Gelatin-layered and multi-sized porous β-tricalcium phosphate for tissue engineering scaffold

The multi-sized porous β-tricalcium phosphate scaffolds were fabricated by freeze drying followed by slurry coating using a multi-sized porous sponge as a template. Then, gelatin was dip coated on the multi-sized porous β-tricalcium phosphate scaffolds under vacuum. The mechanical and biological properties of the fabricated scaffolds were evaluated and compared to the uniformly sized porous scaffolds and scaffolds that were not coated by gelatin. The compressive strength was tested by a universal testing machine, and the cell viability and differentiation behavior were measured using a cell counting kit and alkaline phosphatase activity using the MC3T3-E1 cells. In comparison, the gelatin-coated multi-sized porous β-tricalcium phosphate scaffold showed enhanced compressive strength. After 14 days, the multi-sized pores were shown to affect cell differentiation, and gelatin coatings were shown to affect the cell viability and differentiation. The results of this study demonstrated that the multi-sized porous β-tricalcium phosphate scaffold coated by gelatin enhanced the mechanical and biological strengths.

Gelatin Coating on Quality Attributes of Sausage during Refrigerated Storage

Gelatin-based edible coating was used to reduce the oxidative degradation of low-fat sausages (LFSs) stored at <TEX>$4^{\circ}C$</TEX> for 8 wk under vacuum packaging. The gelatin coating reduced thiobarbituric acid-reactive substances and peroxide value by 21.5 and 26.5%, respectively, compared with the controls. The moisture barrier effect was significantly better for the gelatin coating compared to the control. The gelatin coating reduced moisture loss in sausages by 32.6% over the control. However, the gelatin coating of sausages did not inhibit the growth of either the total plate counts or L. monocytogenes. Data show that gelatin can effectively be used as a natural antioxidative and moisture barrier coating to extend the quality and shelf life of sausages.

Comparative Study of Collagen and Gelatin Coatings on Titanium Surfaces

AbstractThe vast majority of studies in the bone tissue engineering field are focused on the surface modification of titanium scaffolds to obtain integration of the scaffold in the surrounding bone tissue. Our approach consisted in benefiting from the advantages of the cell‐interaction capabilities of collagen and gelatin. The biopolymers were immobilised onto the Ti surface through different methods and the stability of the obtained coatings was determined. The obtained results reveal that covalent immobilisation of collagen and gelatin is required to obtain stable surface coatings.

Small-Interfering RNA-Eluting Surfaces as a Novel Concept for Intravascular Local Gene Silencing

New drug-eluting stent (DES) methods have recently been demonstrated to improve outcomes of intravascular interventions. A novel technique is the design of gene-silencing stents that elute specific small-interfering RNAs (siRNAs) for better vascular wall regeneration. Although siRNAs used to alter gene expression have surpassed expectations in in vitro experiments, the functional and local delivery of siRNAs is still the major obstacle for the in vivo application of RNA interference. In this preliminary in vitro study we investigated a surface-immobilized siRNA delivery technique that would be readily adaptable for local intravascular applications in vivo. The transfection potency of gelatin coatings consisting of a specific siRNA complexed with polyethylenimine (PEI) was examined in primary human endothelial cells by flow cytometry and quantitative real-time polymerase chain reaction. Several media conditions, such as the presence or absence of serum during cultivation, were investigated. Furthermore, different siRNA and PEI amounts, as well as nitrogen/phosphate ratios, were tested for their transfection efficiency. Gelatin coatings consisting of PEI and siRNA against an exemplary endothelial adhesion molecule receptor achieved a significant knockdown of around 70%. The transfection efficiency of the coatings was not influenced by the presence of serum. The results of this preliminary study support the expectation that this novel coating may be favorable for local in vivo gene silencing (for example, when immobilized on stents or balloons for percutanous transluminal coronary angioplasty). However, further animal experiments are needed to confirm the translation into clinical practice. This intriguing technology leads the way to more sophisticated and individualized coatings for the post-DES era, toward silencing of genes involved in the pathway of intimal hyperplasia.

Gelatin Functionalization of Biomaterial Surfaces: Strategies for Immobilization and Visualization

In the present work, the immobilization of gelatin as biopolymer on two types of implantable biomaterials, polyimide and titanium, was compared. Both materials are known for their biocompatibility while lacking cell-interactive behavior. For both materials, a pre-functionalization step was required to enable gelatin immobilization. For the polyimide foils, a reactive succinimidyl ester was introduced first on the surface, followed by covalent grafting of gelatin. For the titanium material, methacrylate groups were first introduced on the Ti surface through a silanization reaction. The applied functionalities enabled the subsequent immobilization of methacrylamide modified gelatin. Both surface modified materials were characterized in depth using atomic force microscopy, static contact angle measurements, confocal fluorescence microscopy, attenuated total reflection infrared spectroscopy and X-ray photo-electron spectroscopy. The results indicated that the strategies elaborated for both material classes are suitable to apply stable gelatin coatings. Interestingly, depending on the material class studied, not all surface analysis techniques are applicable.

Influence of gelatin coatings on compressive strength of porous hydroxyapatite ceramics

Porous ceramics prepared by the foam replication technique have a high porosity and low mechanical stability. It has been reported that coating such porous ceramics with gelatin allows for an improved compressive strength. Little details regarding the influence of important gelatin parameters such as concentration, temperature and drying conditions as well as bloom number which is a measure of the gel rigidity, on this toughening effect are available. This paper investigates the influence of these parameters on compressive strength of gelatin coated porous hydroxyapatite ceramics. It was found that concentration in the gelatin sols has a marked impact whereas sol temperature, bloom number and differing conditions during subsequent drying have only little influence on the compressive strength of the coated ceramics.

Gelatin-Based Laser Direct-Write Technique for the Precise Spatial Patterning of Cells

Laser direct-writing provides a method to pattern living cells in vitro, to study various cell-cell interactions, and to build cellular constructs. However, the materials typically used may limit its long-term application. By utilizing gelatin coatings on the print ribbon and growth surface, we developed a new approach for laser cell printing that overcomes the limitations of Matrigel™. Gelatin is free of growth factors and extraneous matrix components that may interfere with cellular processes under investigation. Gelatin-based laser direct-write was able to successfully pattern human dermal fibroblasts with high post-transfer viability (91% ± 3%) and no observed double-strand DNA damage. As seen with atomic force microscopy, gelatin offers a unique benefit in that it is present temporarily to allow cell transfer, but melts and is removed with incubation to reveal the desired application-specific growth surface. This provides unobstructed cellular growth after printing. Monitoring cell location after transfer, we show that melting and removal of gelatin does not affect cellular placement; cells maintained registry within 5.6 ± 2.5 μm to the initial pattern. This study demonstrates the effectiveness of gelatin in laser direct-writing to create spatially precise cell patterns with the potential for applications in tissue engineering, stem cell, and cancer research.

Non-viral eNOS gene delivery and transfection with stents for the treatment of restenosis

BackgroundIn this study, we have examined local non-viral gene delivery, transfection, and therapeutic efficacy of endothelial nitric oxide synthase (eNOS) encoding plasmid DNA administered using coated stents in a rabbit iliac artery restenosis model.MethodsLipopolyplexes (LPPs) with eNOS expressing plasmid DNA were immobilized on stainless steel stents using poly(D,L-lactide-co-glycolide) (PLGA) and type B gelatin coatings. The gene-eluting stents were implanted bilaterally in the denuded iliac arteries and eNOS transfection and therapeutic efficacy were examined 14 days after implantation.ResultsThe results show that non-viral lipopolyplex-coated stents can efficiently tranfect eNOS locally in the arterial lumen assessed by PCR and ELISA. Human eNOS ELISA levels were significantly raised 24 hours after transfection compared to controls (125 pg eNOS compared to <50 pg for all controls including naked DNA). Local eNOS production suppressed smooth muscle cell proliferation and promoted re-endothelialization of the artery showing a significant reduction in restenosis of 1.75 neointima/media ratio for stents with lipoplexes encoding eNOS compared with 2.3 neointima/media ratio for stents with lipoplexes encosing an empty vector.ConclusionsThese results support the hypothesis that a potent non-viral gene vector encoding for eNOS coated onto a stent can inhibit restenosis through inhibition of smooth muscle cell growth and promotion of a healthy endothelium.

Meat Shelf-life and Extension using Collagen/Gelatin Coatings: A Review

Different factors lead to the end of shelf-life for fresh meat products. The factors depend upon the animal including breed difference and muscle fiber type, external influences such as diet and stress, and post-harvest storage conditions including time, temperature, and packaging atmosphere. The characteristics that indicate the end of shelf-life for fresh meat products include water loss/purge accumulation, color deterioration due to myoglobin oxidation, rancidity due to lipid oxidation, and microbial spoilage. The characteristics can be measured and studied in the laboratory. Meat shelf-life is extended with the application of a surface coating because it provides a water and oxygen barrier. Collagen and gelatin coatings are used as a barrier on meat products to reduce purge, color deterioration, aroma deterioration, and spoilage, improve sensory scores, and act as an antioxidant.