Review of recent advances in bone scaffold fabrication methods for tissue engineering for treating bone diseases and sport injuries

Despite advancements in medical care, the management of bone injuries remains one of the most significant challenges in the fields of medicine and sports medicine globally. Bone tissue damage is often associated with aging, reduced quality of life, and various conditions such as trauma, cancer, and infection. While bone tissue possesses the natural capacity for self-repair and regeneration, severe damage may render conventional treatments ineffective, and bone grafting may be limited due to secondary surgical procedures and potential disease transmission. In such cases, bone tissue engineering has emerged as a viable approach, utilizing cells, scaffolds, and growth factors to repair damaged bone tissue. This research shows a comprehensive review of the current literature on the most important and effective methods and materials for improving the treatment of these injuries. Commonly employed cell types include osteogenic cells, embryonic stem cells, and mesenchymal cells, while scaffolds play a crucial role in bone tissue regeneration. To create an effective bone scaffold, a thorough understanding of bone structure, material selection, and examination of scaffold fabrication techniques from inception to the present day is necessary. By gaining insights into these three key components, the ability to design and construct appropriate bone scaffolds can be achieved. Bone tissue engineering scaffolds are evaluated based on factors such as strength, porosity, cell adhesion, biocompatibility, and biodegradability. This article examines the diverse categories of bone scaffolds, the materials and techniques used in their fabrication, as well as the associated merits and drawbacks of these approaches. Furthermore, the review explores the utilization of various scaffold types in bone tissue engineering applications.

Gelatin-Coated TiO2/Pd Hybrid: A Potentially Useful Nanomaterial to Enhance Antibacterial and Anticancer Properties

Hybrid nanomaterials have attracted considerable interest in biomedicine because of their fascinating characteristics and wide range of applications in targeted drug delivery, antibacterial activity, and cancer treatment. This study developed a gelatin-coated Titanium oxide/palladium (TiO2/Pd) hybrid nanomaterial to enhance the antibacterial and anticancer capabilities. Morphological and structural analyses were conducted to characterize the synthesized hybrid nanomaterial. The surface texture of the hybrid nanomaterials was examined by high-resolution transmission electron microscopy (HR-TEM) and field-emission scanning electron microscopy (FE-SEM). The FE-SEM image revealed the bulk of the spherically shaped particles and the aggregated tiny granules. Energy dispersive X-ray spectroscopy (EDS) revealed Ti, Pd, C, and O. X-ray diffraction (XRD) revealed the gelatin-coated TiO2/Pd to be in the anatase form. Fourier transform infrared spectroscopy examined the interactions among the gelatin-coated TiO2/Pd nanoparticles. The gelatin-coated TiO2/Pd nanomaterials exhibited high antibacterial activity against Escherichia coli (22 mm) and Bacillus subtilis (17 mm) compared to individual nanoparticles, confirming the synergistic effect. More importantly, the gelatin-coated TiO2/Pd hybrid nanomaterial exhibited remarkable cytotoxic effects on A549 lung cancer cells which shows a linear increase with the concentration of the nanomaterial. The hybrid nanomaterials displayed higher toxicity to cancer cells than the nanoparticles alone. Furthermore, the cytotoxic activity against human cancer cells was verified by the generation of reactive oxygen species and nuclear damage. Therefore, gelatin-coated TiO2/Pd nanomaterials have potential uses in treating cancer and bacterial infections.

Design and manufacture of new hybrid hydrogel and superabsorbent polymer for controlled release of fulvic acid based on grafted xanthan gum/gelatin using electron irradiation and its use in fodder corn cultivation

A humic acid-gelatin (HA-Gel) hydrogel, a gallic acid-xanthan gum (GA-XG) hydrogel, a HA-Gel/GA-XG hydrogel, and superabsorbent polymer (SAP) of HA-Gel/GA-XG/polyacrylamide (PAM) hydrogel were synthesized using electron beam irradiation method. The capability of synthesized hydrogels in loading and controlled release of fulvic acid (FA) was studied. The chemical and physical structure of sorbents was confirmed by various analyses. The effect of irradiation dose on mechanical properties, gel percentage, swelling, and absorbency under load (AUL) of the sorbents was investigated. By changing the hydrogel structures into the SAP form, its swelling capacity was increased from 37 to 320 g/g. Both hybrid hydrogel and SAP were reusable for up to 7 cycles. The maximum fertilizer loading capacities for SAP and hybrid hydrogel were 402.1 and, 175.5 mg g-1, respectively. In comparison to hydrogels, the SAP showed a slower FA-release performance. Thus, in soil media, 86 % of FA was released in 15-20 days from the hybrid hydrogel while with the SAP, 81 % of FA was released in 30-35 days. The significant improvement in the growth of fodder corn treated with FA-loaded SAP in the greenhouse media in comparison to the control groups showed the effective performance of the designed SAP, favoring its practical applications.

Cationized gelatin-sodium alginate polyelectrolyte nanoparticles encapsulating moxifloxacin as an eye drop to treat bacterial keratitis

A mucoadhesive polyelectrolyte complex (PEC) nanoparticles were developed for ocular moxifloxacin (Mox) delivery in Bacterial Keratitis (BK). Moxifloxacin-loaded G/CG-Alg NPs were prepared by an amalgamation of cationic polymers (gelatin (G)/cationized gelatin (CG)), and anionic polymer (sodium alginate (Alg)) along with Mox respectively. Mox@CG-Alg NPs were characterized for physicochemical parameters such as particle size (DLS technique), morphology (SEM analysis), DSC, XRD, encapsulation efficiency, drug loading, mucoadhesive study (by texture analyzer), mucin turbidity, and viscosity assessment. The NPs uptake and toxicity of the formulation were analyzed in the Human Corneal Epithelial (HCE) cell line and an ocular irritation study was performed on the HET-CAM. The results indicated that the CG-Alg NPs, with optimal size (217.2 ± 4 nm) and polydispersity (0.22 ± 0.05), have shown high cellular uptake in monolayer and spheroids of HCE. The drug-loaded formulation displayed mucoadhesiveness, trans-corneal permeation, and sustained the release of the Mox. The anti-bacterial efficacy studied on planktonic bacteria/biofilms of P. aeruginosa and S. aureus (in vitro) indicated that the Mox@CG-Alg NPs displayed low MIC, higher zone of bacterial growth inhibition, and cell death compared to free Mox. A significant reduction of bacterial load was observed in the BK-induced mouse model.

Bioactive Polyetheretherketone with Gelatin Hydrogel Leads to Sustained Release of Bone Morphogenetic Protein-2 and Promotes Osteogenic Differentiation

Polyetheretherketone (PEEK) is one of the most promising implant materials for hard tissues due to its similar elastic modulus; however, usage of PEEK is still limited owing to its biological inertness and low osteoconductivity. The objective of the study was to provide PEEK with the ability to sustain the release of growth factors and the osteogenic differentiation of stem cells. The PEEK surface was sandblasted and modified with polydopamine (PDA). Moreover, successful sandblasting and PDA modification of the PEEK surface was confirmed through physicochemical characterization. The gelatin hydrogel was then chemically bound to the PEEK by adding a solution of glutaraldehyde and gelatin to the surface of the PDA-modified PEEK. The binding and degradation of the gelatin hydrogel with PEEK (GPEEK) were confirmed, and the GPEEK mineralization was observed in simulated body fluid. Sustained release of bone morphogenetic protein (BMP)-2 was observed in GPEEK. When cultured on GPEEK with BMP-2, human mesenchymal stem cells (hMSCs) exhibited osteogenic differentiation. We conclude that PEEK with a gelatin hydrogel incorporating BMP-2 is a promising substrate for bone tissue engineering.

Hydrophilic Scaffolds Containing Extracts of Stryphnodendron adstringens and Abarema cochliacarpa for Wound Healing: In Vivo Proofs of Concept

The present work aimed to evaluate the healing effect of hydrophilic polymeric resorbable biomembrane scaffolds containing plant extracts obtained from two different species, both popularly known as Stryphnodendron adstringens or Barbatimão. The hydrogel-based scaffolds were characterized and submitted to biological tests using Wistar rats to evaluate their healing capacity. The wound retraction index and the evaluation of the inflammatory process and tissue collagenization were recorded. The extracts showed antioxidant activity with IC50 between 10 and 20 µg/mL (DPPH assay) and 4–6 mmol Trolox/g (FRAP assay). The extract of Stryphnodendron adstringens (SA) presented gallocatechin, epigallocatechin, and O-methylpigalocatechin, while the extract of Abarema cochliacarpa (AC) presented catechin, dimers of procyanidins, di-O-hydroxide, O-deoxyhexosi-hexoside, and epicatechin. The membranes containing SA extract (GELSA) were more rigid, with a more intense color, but less thick, with a more compact structure and few pores. The membranes containing AC extract (GELAC) presented a mechanical profile like the gelatin membrane (GEL), with greater permeability to water vapor. The GELAC and GELSA membranes showed similar thermal degradation profiles. The wounds treated with the membranes containing the extracts obtained high levels of retraction of the wounds with values around 60% and 80% in three and seven days, respectively. These data indicate that the compounds of both species have promising biological activities in the repair process, showing that the extracts accelerated the healing process due to the lower intensity of the inflammatory reaction and the presence of compounds such as catechin and epigallocatechin.

Immobilization of Gelatin on Fibers for Tissue Engineering Applications: A Comparative Study of Three Aliphatic Polyesters

Immobilization of cell adhesive proteins on the scaffold surface has become a widely reported method that can improve the interaction between scaffold and cells. In this study, three nanofibrous scaffolds obtained by electrospinning of poly(caprolactone) (PCL), poly(L-lactide-co-caprolactone) (PLCL) 70:30, or poly(L-lactide) (PLLA) were subjected to chemical immobilization of gelatin based on aminolysis and glutaraldehyde cross-linking, as well as physisorption of gelatin. Two sets of aminolysis conditions were applied to evaluate the impact of amine group content. Based on the results of the colorimetric bicinchoninic acid (BCA) assay, it was shown that the concentration of gelatin on the surface is higher for the chemical modification and increases with the concentration of free NH2 groups. XPS (X-ray photoelectron spectroscopy) analysis confirmed this outcome. On the basis of XPS results, the thickness of the gelatin layer was estimated to be less than 10 nm. Initially, hydrophobic scaffolds are completely wettable after coating with gelatin, and the time of waterdrop absorption was correlated with the surface concentration of gelatin. In the case of all physically and mildly chemically modified samples, the decrease in stress and strain at break was relatively low, contrary to strongly aminolyzed PLCL and PLLA samples. Incubation testing performed on the PCL samples showed that a chemically immobilized gelatin layer is more stable than a physisorbed one; however, even after 90 days, more than 60% of the initial gelatin concentration was still present on the surface of physically modified samples. Mouse fibroblast L929 cell culture on modified samples indicates a positive effect of both physical and chemical modification on cell morphology. In the case of PCL and PLCL, the best morphology, characterized by stretched filopodia, was observed after stronger chemical modification, while for PLLA, there was no significant difference between modified samples. Results of metabolic activity indicate the better effect of chemical immobilization than of physisorption of gelatin.

Osteogenesis Improvement of Gelatin-Based Nanocomposite Scaffold by Loading Zoledronic Acid

Bisphosphonates (BPs) such as Zoledronic acid (ZA) are a subset of synthetic small molecules, which are now marketed as the main drugs to stimulate the growth and differentiation of osteoblast cells, thereby increasing bone formation as well as preventing bone loss. Also, Halloysite Nanotubes (HNTs)-polymer composites have attracted a lot of attention due to their high surface-to-volume ratio, low density, and high hydrophilicity, and are easily dispersed in hydrophilic biopolymers. In addition, their ability to carry enough amounts of drugs and the ability to control release has been demonstrated. Based on studies, the Gelatin-based scaffold with Halloysite nanotube (HNT) has the capacity as a drug carrier and Zoledronic acid (ZA) sustains release. Previous studies show that using ZA intravenously has some severe side effects and limitations. But by attention to the advantages of its osteogenesis, the current study has been done in order to reduce the side effects of local delivery of it. The 3-dimensional scaffolds were prepared by the Freeze-drying method. Characterization methods such as FE-SEM, FTIR, XRD, and release behavior of the scaffold has been performed to evaluate the features of the scaffolds. In fact, as-prepared Gel-HNT/ZA release 49% ZA in Phosphate Buffered Saline (PBS) within 21 days. The mechanical properties have been increased after adding HNTs and ZA from 10.27 to 26.18 MPa. Also, the water absorption has been increased after adding HNTs and ZA from 1.67 to 5.02 (g/g). Seeded human Adipose stem cells (hASCs) on the prepared scaffolds showed that the ZA effectively elevated the proliferation of the hASCs and also the MTT results proved the non-toxicity of all prepared scaffolds by high cell viability (˃80%). The osteogenic differentiation has been accelerated as displayed by ALP and Ca assay. The results propose that the HNTs-loaded Gelatin scaffold could control the releasing of ZA and its localized delivery at the defect site, simultaneously promoting the mechanical and osteogenesis ability of gelatin-based scaffolds.

Gallic Acid-Containing Gelatin-Based Nonwoven Mat with Synergistic Photodegradation and Photoindication Function for Reducing Nicotine

Cigarette smoking is a popular habit that has negative health consequences for populations. In this study, we developed a gallic acid-containing, gelatin-based nonwoven mat with photodegradation and photoindication functions. This could react with sidestream cigarette smoke and simultaneously inhibit the activity of the microbe growth in the air. The results of a fluorescence emission spectrum evidenced this photoindication function. Neither the nicotine nor gallic acid showed a redshift emission spectrum. However, the emission spectrum of the nonwoven mat exhibited the redshift and increased in intensity after absorbing the sidestream cigarette smoke. In this spectral evidence, the natural polymer played a key role in the photoindication function’s display because it could dissolve the nicotine of the sidestream cigarette smoke and cause it to react with the gelatin structure. The high performance liquid chromatography–mass spectroscopy results indicated that the gallic acid and ultraviolet (UV) light enhanced the absorption of nicotine and nicotine-like derivatives, which were dissolved by the Tween 80 of nonwoven mat. The liquid paraffin and Tween 80 could oxidize, dehydrogenate, and demethylate the nicotine that was absorbed by the gelatin nonwoven mat. In conclusion, the nonwoven mat developed in this study provided the functions to filter the nicotine of sidestream smoke and activate the photoindication property by absorbing 365-nm UV light.

Bioactive Edible Films Based on Arrowroot Starch Incorporated with Cranberry Powder: Microstructure, Thermal Properties, Ascorbic Acid Content and Sensory Analysis

The growing global awareness about environmental preservation has stimulated the search for alternatives to replace conventional plastics made from fossil sources. One of the advantages is using polymers from renewable sources, such as starch and gelatin, which, in addition to being biodegradable, may also be edible. The incorporation of cranberry into a polymeric matrix can transfer bioactive composite films, colour and flavour to the film, which are characteristic of this fruit, expanding its application to fruit stripes or colourful coatings for specific foods. In this context, the aim of this work was to evaluate the influence of the incorporation of 0, 5, 15, 25, 35, 45 and 55% (solids mass/biopolymer mass) cranberry powder on the microstructure, thermal properties, ascorbic acid content and sensory analysis of gelatin and arrowroot starch films obtained by casting. Scanning electron microscopy (SEM) images showed that the incorporation of cranberry made the film surface rough and irregular. All films presented an X-ray diffraction pattern typical of a semicrystalline material. The glass transition temperature (T_g) decreased when increasing the concentration of cranberry in films. All films with cranberry presented high ascorbic acid content and were well accepted by the tasters when sensory analysis was performed.

Environmentally Friendly Gelatin/β-Cyclodextrin Composite Fiber Adsorbents for the Efficient Removal of Dyes from Wastewater

In this paper, environmentally friendly gelatin/β-cyclodextrin (β-CD) composite fiber adsorbents prepared by electrospinning were used for the removal of dyes from wastewater. Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and a universal materials tester were employed to characterize the internal structures, surface morphologies and mechanical strength of the composite fiber adsorbents. Additionally, the fiber was evaluated as an adsorbent for the removal of methylene blue (MB) from aqueous solution. The effects of the raw material ratio, pH, temperature, concentration and adsorption time were studied. The results show that the gelatin/β-CD composite fiber adsorbents possess excellent mechanical strength and high adsorption efficiency for MB. The adsorption equilibrium and adsorption kinetics are well-described by the Langmuir isotherm model and the pseudo-second-order kinetic model, respectively. The theoretical maximum adsorption capacity is 47.4 mg·g-1. Additionally, after nine successive desorption-adsorption cycles, the removal rate is still over 70%. Moreover, the gelatin/β-CD composite fiber adsorbents exhibit excellent adsorption capability for basic fuchsin, gentian violet, brilliant blue R and malachite green dyes. Therefore, owing to the characteristics of degradability, low cost and high-efficiency, the gelatin/β-CD composite fiber can be used as an efficient adsorbent for the removal of dyes from wastewater.

Novel alginate-di-aldehyde cross-linked gelatin/nano-hydroxyapatite bioscaffolds for soft tissue regeneration

The present study describes the fabrication of a novel alginate-di-aldehyde (ADA) cross-linked gelatin (GEL)/nano-hydroxyapatite (nHAp) bioscaffold by lyophilization process. The physico-chemical properties of the scaffolds were evaluated in order to assess its suitability for tissue engineering application. ADA was prepared from periodate oxidation of alginate which facilitate the crosslinking between free amino group of gelatin and available aldehyde group of ADA through Schiff's base formation. nHAp was synthesized from waste egg-shells by wet chemical method. The synthesized HAp was found crystalline and nanosize (~45 nm) by XRD and TEM analysis respectively. Ca to P ratio of nHAp is 1.51 as observed by EDX confirmed the suitability of the scaffold for biomedical application. The crosslinked ADA increases thermal stability of scaffolds. Water uptake and degradation ability significantly reduced with the increase of nHAp in the scaffold due to the higher stiffness contributed by nHAp. SEM analysis revealed that the pore size and porosity of the scaffolds declines with the proliferation of nHAp in the scaffolds. XRD analysis of the scaffolds shows the increase of crystallinity in the composites due to incorporation of nHAp and ADA. Cytotoxicity of the all scaffolds were examined by normal kidney epithelial cells (Vero cells) and the results confirmed the non-toxicity of the scaffolds, which proved it is extremely cytocompatible. These tunable physical properties and enhance biocompatibility of prepared scaffold offer advance application in soft tissue regeneration and could be a promising candidate for biomedical application.

Enhanced bone regeneration composite scaffolds of PLLA/β-TCP matrix grafted with gelatin and HAp

The composite polylactide PLLA/β-TCP scaffolds were fabricated by solution casting and were coated with gelatin/hydroxyapatite (Gel/HAp) to improve the biological properties of the composite scaffolds. The Gel/HAp mixture was prepared using an in situ reaction, and a grafting-coating method was used to increase the efficiency of coating the PLLA/β-TCP matrix with Gel/HAp. First, free amino groups were introduced by 1,6-hexanediamine to aminolyze the PLLA/β-TCP matrix surface. Second, glutaraldehyde was coupled to Gel/HAp as a crosslinking agent. The structure and properties of Gel/HAp-modified PLLA/β-TCP films were characterized by Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and water contact angle measurements (WCA). The experimental results show that 23 wt% HAp was uniformly dispersed in the gelatin coating by in situ synthesis. The Gel/HAp composite coating was successfully immobilized on the aminolyzed PLLA/β-TCP surface via a chemical grafting method, which promoted a lower degradation rate and was more hydrophilic than a physical grafting method. The Gel/HAp composite coating adhered tightly and homogeneously to the hydrophobic PLLA/β-TCP surface. Moreover, mouse embryo osteoblast precursor (MC3T3-E1) cells grown on the scaffolds were behaviorally and morphologically characterized. The results indicated that the Gel/HAp composite coating was favorable for the attachment and proliferation of preosteoblasts and that Gel/HAp-NH-PLLA/β-TCP would be a candidate scaffold for bone repair.

Delivery of Mesenchymal Stem Cells from Gelatin-Alginate Hydrogels to Stomach Lumen for Treatment of Gastroparesis

Gastroparesis (GP) is associated with depletion of interstitial cells of Cajal (ICCs) and enteric neurons, which leads to pyloric dysfunction followed by severe nausea, vomiting and delayed gastric emptying. Regenerating these fundamental structures with mesenchymal stem cell (MSC) therapy would be helpful to restore gastric function in GP. MSCs have been successfully used in animal models of other gastrointestinal (GI) diseases, including colitis. However, no study has been performed with these cells on GP animals. In this study, we explored whether mouse MSCs can be delivered from a hydrogel scaffold to the luminal surfaces of mice stomach explants. Mouse MSCs were seeded atop alginate-gelatin, coated with poly-l-lysine. These cell-gel constructs were placed atop stomach explants facing the luminal side. MSCs grew uniformly all across the gel surface within 48 h. When placed atop the lumen of the stomach, MSCs migrated from the gels to the tissues, as confirmed by positive staining with vimentin and N-cadherin. Thus, the feasibility of transplanting a cell-gel construct to deliver stem cells in the stomach wall was successfully shown in a mice stomach explant model, thereby making a significant advance towards envisioning the transplantation of an entire tissue-engineered 'gastric patch' or 'microgels' with cells and growth factors.

Graphene oxide decorated electrospun gelatin nanofibers: Fabrication, properties and applications

Gelatin nanofiber fabricated by electrospinning process is found to mimic the complex structural and functional properties of natural extracellular matrix for tissue regeneration. In order to improve the physico-chemical and biological properties of the nanofibers, graphene oxide is incorporated in the gelatin to form graphene oxide decorated gelatin nanofibers. The current research effort is focussed on the fabrication and evaluation of physico-chemical and biological properties of graphene oxide-gelatin composite nanofibers. The presence of graphene oxide in the nanofibers was established by transmission electron microscopy (TEM). We report the effect of incorporation of graphene oxide on the mechanical, thermal and biological performance of the gelatin nanofibers. The tensile strength of gelatin nanofibers was increased from 8.29±0.53MPa to 21±2.03MPa after the incorporation of GO. In order to improve the water resistance of nanofibers, natural based cross-linking agent, namely, dextran aldehyde was employed. The cross-linked composite nanofibers showed further increase in the tensile strength up to 56.4±2.03MPa. Graphene oxide incorporated gelatin nanofibers are evaluated for bacterial activity against gram positive (Staphylococcus aureus) and gram negative (Escherichia coli) bacteria and cyto compatibility using mouse fibroblast cells (L-929 cells). The results indicate that the graphene oxide incorporated gelatin nanofibers do not prevent bacterial growth, nevertheless support the L-929 cell adhesion and proliferation.

Fabrication of poly(ester-urethane)urea elastomer/gelatin electrospun nanofibrous membranes for potential applications in skin tissue engineering

In this study, PEUU was blended with gelatin for electrospun nanofiber and nanoyarn. PEUU/gelatin with a mass ratio of 75 : 25 showed better comprehensive property than nanofiber thus paving way for the further research in tissue engineering field.