Loaded Gelatin Microspheres Research Articles

Comparative study of sodium nitrite loaded gelatin microspheres and gelatin gels: Physicochemical and antibacterial properties

In this study, under the action of microbial transglutaminase (mTGase), sodium nitrite (NaNO2) loaded type-A gelatin microspheres (NaNO2-GAMs) were prepared by water-in-oil (W/O) emulsification cross-linking method, and NaNO2 loaded type-A gelatin gels (NaNO2-GAGs) were prepared by cross-linking freeze-drying method. The physicochemical properties and antibacterial effect of NaNO2-GAMs and NaNO2-GAGs were compared. Both scanning electron microscope and fourier transform infrared spectroscopy revealed that NaNO2 was successfully encapsulated in the microspheres and gels. The NO release and encapsulation efficiency of NaNO2 increased with mTGase ranging from 0 to 30 U/g. Rheological analysis confirmed that mTGase increased the viscosity of NaNO2-GAMs and NaNO2-GAGs. In addition, NaNO2-GAMs and NaNO2-GAGs were applied to actual environment (as in low-temperature sausages), and the antibacterial effect was judged according to the number of microbial colonies. In summary, the NaNO2-GAMs showed better antibacterial effect than NaNO2-GAGs, achieving the effect of extending the shelf life of meat products.

Transdermal delivery of sinapine thiocyanate by gelatin microspheres and hyaluronic acid microneedles for allergic asthma in guinea pigs

Dissolving microneedles (MNs) are an efficient, safe, and generally painless method for transdermal distribution of poorly permeable medicines. Here, dissolving composite MNs were prepared from sinapine thiocyanate (ST)-loaded gelatin microspheres (GMS) and hyaluronic acid (HA). To immobilize ST in MNs, we used a two-step centrifuging and molding method. When ST-GMS/ST-HA MNs were placed on the skin, they showed extraordinary mechanical strength and dissolved slowly. In vitro, skin implantation ability was assessed with fluorescein isothiocyanate staining, which revealed progressive penetration from the puncture site into deeper tissues. The feasibility of transdermal delivery of ST-GMS/ST-HA MNs in allergic asthma guinea pigs was then determined through in vivo pharmacodynamic and pharmacokinetic tests. The results indicated that ST-GMS/ST-HA MNs, in comparison with the traditional subcutaneous application approach, achieved both high efficiency and continuous release of ST. Therefore, this device is promising for the delivery ST for allergic asthma therapy.

Vancomycin Loaded Gelatin Microspheres Containing Wet Spun Poly(ε-caprolactone) Fibers and Films for Osteomyelitis Treatment

In this study, it was aimed to develop drug eluting biodegradable and biocompatible bone supportive fibers and films, which can locally be applicable on the infected bone defect area for osteomyelitis treatment. For this purpose, vancomycin (Vm) loaded gelatin (G) microspheres were prepared and dispersed into poly(e-caprolactone) (PCL) solution and then the suspension was processed as films and fibers by solvent casting and wet spinning techniques, respectively. The mean particle size distribution and morphology of Vm loaded G microspheres were characterized by laser diffraction method and scanning electron microscopy, respectively. In vitro Vm release profiles and release kinetics from microsphere, fiber and film formulations were investigated. In vitro biodegradation properties of fiber and film formulations were examined in both hydrolytic and enzymatic media during 25 days period. The cytotoxicity of Vm eluting films and fibers were tested on L929 cells by MTT assay. Presence of PCL in film and fiber formulations retarded the release of Vm from microspheres and provided long term sustained release. Vm eluting films and fibers exhibited strong antibacterial properties against Staphylococcus aureus and Staphylococcus epidermidis.

Porous, lithium-doped calcium polyphosphate composite scaffolds containing vascular endothelial growth factor (VEGF)-loaded gelatin microspheres for treating glucocorticoid-induced osteonecrosis of the femoral head

Glucocorticoids-induced osteonecrosis of femoral head (GIONFH) is difficult to treat due to the pathophysiology remains uncertain. Core decompression and bone grafting are regarded as effective measures for treating early GIONFH. Furthermore, commonly used bone graft materials at nowadays are still unsatisfactory. We generated a novel calcium polyphosphate (CPP) composite scaffold, which contains Li and VEGF-loaded gelatin microspheres (LiCPP/GMs/VEGF). The LiCPP/GMs/VEGF scaffold also demonstrated a porosity of 70.5% ± 2.3% with interconnected porous structures, and pore sizes of 100–200 μm and compressive strength of 3.7 MPa. Additionally, bone marrow mesenchymal stem cells (BMSCs) were seeded on scaffolds in vitro. Further characterization showed that the LiCPP/GMs/VEGF scaffolds were biocompatible and enhanced osteogenesis and angiogenesis in vitro. Using a rabbit model of GIONFH, LiCPP/GMs/VEGF scaffolds were implanted into the bone tunnels of core decompression in the femoral head for 12 weeks. Radiographic, histological analysis and western blot analysis demonstrated that the LiCPP/GMs/VEGF scaffolds exhibited good biocompatibility, and osteogenic and angiogenic activity in vivo. Besides, the osteogenic and angiogenic factors were increased along with VEGF release and the activation of factors in Wnt signal pathway. In conclusion, the LiCPP/GMs/VEGF scaffold has an effect on improving the osteogenesis and angiogenesis, which benefited to repair the GIONFH.

Accelerated wound healing and its promoting effects of biomimetic collagen matrices with siderophore loaded gelatin microspheres in tissue engineering

The prolonged inflammation and elevation of Matrix Metalloproteniases (MMPs) at the wound site causes significant degradation of Extracellular matrix (ECM) which cause delays the process of wound healing. Hence the development of therapeutic dressing matrices to control and to positively regulate MMPs balance was considered important in achieving faster healing. The design of biomaterial matrices of collagen scaffold has the challenge to mimic the function of ECM and emulate to the attraction of fibroblast migration at wound site. Herein, we report the fabricated Collagen (COL) matrices impregnated with Siderophore loaded Gelatin Microspheres (SGM) as a delivery system to control both infection and protease levels in the wound site for accelerated healing. The fabricated collagen scaffold impregnated with siderophore loaded gelatin microspheres (COL-SGM) was characterized physiochemically using Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM) and swelling behaviour. The COL-SGM scaffold possesses good swelling ability and also exhibited better morphology for the cell adhesion and proliferation. The in vitro biocompatibility and in vitro fluorescence activity of the developed scaffold revealed to possess good cell proliferation and migration against NIH 3T3 fibroblast and Human keratinocytes (HaCaT) cell lines. Furthermore, the in vivo evaluation offered the advantage of neutralizing the excessive proteases and delivered the siderophore in controlled fashion depending on the level of wound exudates with modulated MMPs. Moreover, the COL-SGM scaffold exhibited with increase in the collagen synthesis and faster reepitheliazation of wounds. Thus the developed COL-SGM scaffold achieved improvements in biocompatibility and act as a potent MMP inhibitor to improve wound healing efficiency in tissue engineering application.

Controlled delivery of platelet-derived growth factor-BB from injectable microsphere/hydrogel composites

Platelet-derived growth factor-BB (PGDF-BB) loaded gelatin microspheres with an average size of about 2μm was incorporated into chitosan/silk fibroin/glycerophosphate (GP) solutions to prepare composites. The formulated composite solutions were able to form into hydrogels in a temperature range between 32 and 37°C at a pH of ca.7. They had good fluidity at 25°C and showed shear-thinning features at both 25 and 37°C, revealing that they are injectable at room temperature. Elastic modulus of some composites at 37°C was about 10-fold higher than that of chitosan/GP gel, confirming that these composites behave like mechanically strong gels. Optimal composites showed abilities to administrate PDGF-BB release in an approximately linear manner up to 5 weeks. The PDGF-BB release could be regulated by the PDGF-BB load and the silk fibroin content in the composites in an individual or cooperative way. In vivo degradation of composites demonstrated that some of them had markedly enhanced degradation endurance as compared to the chitosan/GP gel. PDGF-BB-stimulated DNA synthesis in Balb/c 3T3 fibroblasts and PDGF-BB-induced cell migration suggested that the bioactivity of released PDGF-BB was well retained.

Covalently antibacterial alginate-chitosan hydrogel dressing integrated gelatin microspheres containing tetracycline hydrochloride for wound healing

An antibacterial and biodegradable composite hydrogel dressing integrated with microspheres is developed for drug delivery and wound healing. The mechanism of gelation is attributed to the Schiff-base reaction between aldehyde and amino groups of oxidized alginate (OAlg) and carboxymethyl chitosan (CMCS). To enhance antibacterial and mechanical properties, tetracycline hydrochloride (TH) loaded gelatin microspheres (GMs) were fabricated by an emulsion cross-linking method, followed by integrating into the OAlg-CMCS hydrogel to produce a composite gel dressing. In vitro gelation time, swelling, degradation, compressive modulus and rheological properties of the gel dressing were investigated as the function of microsphere ratios. With increasing ratios of microspheres from 10 to 40mg/mL, the composite dressing manifested shorter gelation time and lower swelling ratios, as well as higher mechanical strength. Comparing to other formulations, the gel dressing with 30mg/mL microspheres showed more suitable stabilities and mechanical properties for wound healing. Also, in vitro drug release results showed that the loaded TH could be sustained release from the composite gel dressing by contrast with pure hydrogels and microspheres. Furthermore, powerful bacteria growth inhibition effects against Escherichia coli and Staphylococcus aureus suggested that the composite gel dressing, especially the one with 30mg/mL GMs containing TH, has a promising future in treatment of bacterial infection.

Porous titanium scaffold surfaces modified with silver loaded gelatin microspheres and their antibacterial behavior

Abstract Recent years, porous titanium (PT) attracts much attention because of its growing application as medical implants. However, bacterial infections related to implants remain one of the most common and serious complications. In this study, silver loaded gelatin microspheres (Ag/GMSs) were fabricated and incorporated into porous titanium to get antibacterial implants. Prior to incorporating microspheres, oxide film and micro/nanostructures were formed on porous titanium by micro-arc oxidation (MAO) to improve its activity, and the resulted sample is named MPT. Samples were characterized with scanning electron microscope, energy dispersive X-ray spectroscope, transmission electron microscope, X-ray diffractometer, laser scattering particle analyzer and atomic absorption spectrometer. The results showed that Ag0 particles were loaded to the gelatin microspheres with average diameter of 4.46 μm and Ag/GMSs distributed uniformly on the pore walls of PT and MPT. Ag0 particles were demonstrated not only formed on the surface of gelatin microspheres but also inside them. The silver loaded samples exhibited a high antibacterial ability against both Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The MPT sample was not only better in supporting osteoblast cell viability and good cell proliferation, but also was beneficial to immobilize the silver loaded microspheres to achieve a stronger antibacterial effect than PT. The MPT sample with silver loaded gelatin microspheres increased the cumulative release period of Ag and reached to more than ten days. The main idea of this study also elicited a new surface functionalization strategy for improving antibacterial ability of porous titanium.

Effects of bovine lactoferrin in surgically created bone defects on bone regeneration around implants.

The aim of this experimental study was to evaluate the effect of bovine lactoferrin (bLF)-loaded gelatin microspheres (GM) used in combination with anorganic bovine bone on bone regeneration in surgically created bone defects around tooth implants. Twenty-four uniform bone defects were created in the frontal bone via an extraoral approach in 12 domestic pigs. Twenty-four implants were placed at the center of the defects. In eight animals one of these defects was filled with 0.3 mL anorganic bovine bone while the other was left empty. In four animals, all defects were filled with 3 mg/defect bLF-loaded GM and anorganic bovine bone. All the defects were covered with collagen membranes. All animals were sacrificed after 10 weeks of healing, and the implants with the surrounding bone defects were removed en bloc. Undecalcified sections were prepared for histomorphometric analysis. The mean total area of hard tissue was 26.9 ± 6.0% in the empty defect group, 31.8 ± 8.4% in the graft group, and 47.6 ± 5.0% in the lactoferrin group (P < 0.001). The mean area of newly formed bone was 26.9 ± 6.0% in the empty defect group, 22.4 ± 8.2% in the graft group, and 46.1 ± 5.1% in the lactoferrin group (P < 0.001). The mean residual graft area was 9.4 ± 3.2% in the graft group and 1.5 ± 0.6% in the lactoferrin group (P < 0.001). The mean proportion of bone-implant contact in the defect region was 21.9 ± 8.4% in the empty defect group, 26.9 ± 10.1% in the graft group and 29.9 ± 10.3% in the lactoferrin group (P = 0.143). These data indicate that a combination of 3 mg bLF-loaded GM and bovine-derived HA promotes bone regeneration in defects around implants.

Driving cartilage formation in high-density human adipose-derived stem cell aggregate and sheet constructs without exogenous growth factor delivery.

An attractive cell source for cartilage tissue engineering, human adipose-derived stem cells (hASCs) can be easily expanded and signaled to differentiate into chondrocytes. This study explores the influence of growth factor distribution and release kinetics on cartilage formation within 3D hASC constructs incorporated with transforming growth factor-β1 (TGF-β1)-loaded gelatin microspheres. The amounts of microspheres, TGF-β1 concentration, and polymer degradation rate were varied within hASC aggregates. Microsphere and TGF-β1 loading concentrations were identified that resulted in glycosaminoglycan (GAG) production comparable to those of control aggregates cultured in TGF-β1-containing medium. Self-assembling hASC sheets were then engineered for the production of larger, more clinically relevant constructs. Chondrogenesis was observed in hASC-only sheets cultured with exogenous TGF-β1 at 3 weeks. Importantly, sheets with incorporated TGF-β1-loaded microspheres achieved GAG production similar to sheets treated with exogenous TGF-β1. Cartilage formation was confirmed histologically via observation of cartilage-like morphology and GAG staining. This is the first demonstration of the self-assembly of hASCs into high-density cell sheets capable of forming cartilage in the presence of exogenous TGF-β1 or with TGF-β1-releasing microspheres. Microsphere incorporation may bypass the need for extended in vitro culture, potentially enabling hASC sheets to be implanted more rapidly into defects to regenerate cartilage in vivo.

A comparison of fibrin, agarose and gellan gum hydrogels as carriers of stem cells and growth factor delivery microspheres for cartilage regeneration

The limited intrinsic repair capacity of articular cartilage has led to the investigation of different treatment options to promote its regeneration. The delivery of hydrogels containing stem or progenitor cells and growth factor releasing microspheres represents an attractive approach to cartilage repair. In this study, the influence of the encapsulating hydrogel on the ability of progenitor cells coupled with TGF-β3 releasing microspheres to form cartilaginous tissue was investigated. Fibrin, agarose and gellan gum hydrogels containing TGF-β3 loaded gelatin microspheres and progenitor cells derived from the infrapatellar fat-pad of the knee were cultured for 21 days in a chemically defined media. In the presence of TGF-β3 releasing microspheres, gellan gum hydrogels were observed to facilitate greater cell proliferation than fibrin or agarose hydrogels. Histological and biochemical analysis of the hydrogels indicated that fibrin was the least chondro-inductive of the three hydrogels, while agarose and gellan gum appeared to support more robust cartilage formation as demonstrated by greater sGAG accumulation within these constructs. Gellan gum hydrogels also stained more intensely for collagen type II and collagen type I, suggesting that although total collagen synthesis was higher in these constructs, that the phenotype may be more fibrocartilaginous in nature than normal hyaline cartilage. This study demonstrates how the encapsulating hydrogel can have a significant impact on the ability of stem cells to form cartilage when incorporated into a growth factor delivery system.

Magnetic and compartmental targeting of azathioprine using gelatin microspheres: formulation, physicochemical characterization and in vitro release studies

Azathioprine loaded gelatin microspheres were formulated to control/target drug release in an arthritic joint by magnetic force or intra-articular injection. Glutaraldehyde cross linked microspheres were characterized for drug loading, entrapment efficiency, gas chromatography, magnetite content, particle size, scanning electron microscopy (SEM), Fourier-Infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC) and in vitro release studies. The gelatin microspheres loaded with azathioprine showed 17% of drug loading with 82% of entrapment efficiency. Gelatin magnetic microspheres showed 13% of loading with 87% of entrapment efficiency. Gas chromatography confirms absence of residual glutaraldehyde in the microspheres. The magnetite content of the azathioprine loaded gelatin magnetic microsphere was 25.7% w/w. The average particle sizes of gelatin nonmagnetic and magnetic microspheres were 41 and 54 µm, respectively. SEM confirms the spherical nature of the microspheres. FT-IR revealed the absence of drug polymer interaction, and DSC suggested amorphous nature of entrapped drug in the microspheres. The formulated microspheres could release the drug over a period of 48 h.

Lung-targeted delivery system of curcumin loaded gelatin microspheres

The purpose of the study is to design and evaluate curcumin loaded gelatin microspheres (C-GMS) for effective drug delivery to the lung. C-GMS was prepared by the emulsification-linkage technique and the formulation was optimized by orthogonal design. The mean encapsulation efficiency and drug loading of the optimal C-GMS were 75.5 ± 3.82 % and 6.15 ± 0.44%, respectively. The C-GMS presented a spherical shape and smooth surface with a mean particle diameter of 18.9 μm. The in vitro drug release behavior of C-GMS followed the first-order kinetics. The tissue distribution showed that the drug concentrations at lung tissue for the C-GMS suspension were significantly higher than those for the curcumin solution, and the Ce for lung was 36.19. Histopathological studies proved C-GMS was efficient and safe to be used as a passive targeted drug delivery system to the lung. Hence, C-GMS has a great potential for the targeted delivery of curcumin to the lung.

BSA - loaded gelatin microspheres: Comparative studies on biodegradation and drug release in presence of collagenase and trypsin

Certain variations in the process parameters (emulsification time, surfactant concentration) were performed in order to prepare BSA-loaded gelatin microspheres with particle size ranging from 1 to 10 µm and high loading efficiency using a procedure originally employed by Tabata and Ikada. In vitro degradation and drug release studies in the presence of trypsin and collagenase, respectively, were performed in order to evaluate the potential of gelatin microspheres as regulated and sustained release systems for oral vaccination. Degradation data showed that the preparation procedure had provided prolonged degradation in the presence of both enzymes, suggesting complete in vivo degradation. Exponential dependence of the amount of drug released on time was evidenced. The diffusion coefficients were superior to 0.5 indicating the Case II anomalous Fickian diffusion, except for the particles smaller than 5 µm where in the presence of collagenase the transition to Super Case II transport was observed due to the higher rate of polymer degradation and BSA diffusion through the matrix. The mathematical modeling of drug release showed a biphasic release pattern in the presence of both enzymes, where the rate constants for the initial time release confirmed the influence of the particle size and/or enzymatic degradation rate on the drug release rate.

Biodistribution studies of BSA loaded gelatin microspheres after peroral application.

Biodistribution studies of radiolabelled [131I]BSA loaded gelatin microspheres were carried out on BALB/c mice after peroral administration. To two groups, the radiolabelled [131I]BSA gelatin microspheres with different mean particle size, 1.196+/-1.961 and 7.028+/-1.231 microm were administered orally. To the control group, a solution of [131I]BSA was also orally administered. Biodistribution was followed periodically within 15 days as a percent of total radioactivity present in stomach, small intestine with Peyer's patches and mesentery, colon with Peyer's patches, appendix and mesentery, liver, spleen, blood, kidney, lungs and heart. The biodistribution data confirmed that uptake in mice into Peyer's patches and passage to the liver and spleen via the mesentery lymph supply and nodes, increased with decreasing particle size.

Biodegradation and drug release studies of BSA loaded gelatin microspheres.

Certain variations in the process parameters (emulsification time, surfactant concentration) were performed in order to prepare BSA-loaded gelatin microspheres with high loading efficacy and particle size ranging from 1 to 10 microm using a procedure originally employed by Tabata and Ikada. The mathematical modelling of drug release in the presence of collagenase showed a biphasic release pattern, where the rate constant for the initial time release confirmed the influence of the particle size and/or enzymatic degradation rate on drug release rate.