Gelatin Spheres Research Articles

Injectable microgels containing genetically engineered bacteria for colon cancer therapy through programmed Chemokine expression

Chemokines are emerging as important targets for cancer immunotherapy due to their role in regulating immune cell migration and activation within the tumor microenvironment. Effective delivery and sustained presence of chemokines at the tumor site is essential for recruiting and activating immune cells to exert anti-tumor effects. In this study, we report a genetically engineered bacterial cell factory designed for the continuous production of chemokine CCL21 in a controlled manner. To decrease the formation of infusion bodies (IBs) in bacteria, we used thioredoxin (Trx) as the fusion partner and cloned at N-terminal of the target protein. The commonly used promoters, pT7-LacO, pBV220, and pDawn, were employed to explore the influence of various inducers on the expression of CCL21 in bacteria. The engineered bacteria were finally encapsulated within spherical gelatin methacryloyl (GelMA) microgels, which not only maintained bacterial viability but also prolonged their retention in the intestines of mice. As a result, the sustained presence and localized production of CCL21 led to effective suppression of tumor growth.

New Functional Orbital-free Within DFT for Metallic Systems

I present the continuation of a study on Laplacian Level Kinetic Energy (KE) functionals applied to metallic nanosystems. The development of novel Kinetic Energy functionals is an important topic in density functional theory (DFT). The nanoparticles are patterned using gelatin spheres of different sizes, background density and number of electrons. To reproduce the correct kinetic and potential energy density of the various nanoparticles, the use of semilocal descriptors is necessary. Need an explicit density functional expression for the kinetic energy of electrons, including the first e second functional derivative, i.e. the kinetic potential and the kinetic kernel, respectively. The exact explicit form of the non interacting kinetic energy, as a functional of the electron density, is known only for the homogeneous electron gas (HEG), i.e., the Thomas-Fermi (TF) local functional and for 1 and 2 electron systems, i.e., the von Weizsacker (VW) functional. In between these two extreme cases, different semilocal or non local approximations were developed in recent years. Most semilocal KE functionals are based on modifications of the second-order gradient expansion (GE2) or fourth-order gradient expansion (GE4). I find that the Laplacian contribute is fundamental for the description of the energy and the potential of nanoparticles. I propose a new LAP2 semilocal functional which, better than the previous ones, allows us to obtain fewer errors both of energy and potential. More details of the previous calculations can be found in my 2 previous works which will be cited in the text.

Scalable manufacture of therapeutic mesenchymal stromal cell products on customizable microcarriers in vertical wheel bioreactors that improve direct visualization, product harvest, and cost

Background aimsHuman mesenchymal stromal cells (hMSCs) and their secreted products show great promise for treatment of musculoskeletal injury and inflammatory or immune diseases. However, the path to clinical utilization is hampered by donor-tissue variation and the inability to manufacture clinically relevant yields of cells or their products in a cost-effective manner. Previously we described a method to produce chemically and mechanically customizable gelatin methacryloyl (GelMA) microcarriers for culture of hMSCs. Herein, we demonstrate scalable GelMA microcarrier-mediated expansion of induced pluripotent stem cell (iPSC)-derived hMSCs (ihMSCs) in 500 mL and 3L vertical wheel bioreactors, offering several advantages over conventional microcarrier and monolayer-based expansion strategies. MethodsHuman mesenchymal stromal cells derived from induced pluripotent cells were cultured on custom-made spherical gelatin methacryloyl microcarriers in single-use vertical wheel bioreactors (PBS Biotech). Cell-laden microcarriers were visualized using confocal microscopy and elastic light scattering methodologies. Cells were assayed for viability and differentiation potential in vitro by standard methods. Osteogenic cell matrix derived from cells was tested in vitro for osteogenic healing using a rodent calvarial defect assay. Immune modulation was assayed with an in vivo peritonitis model using Zymozan A. ResultsThe optical properties of GelMA microcarriers permit noninvasive visualization of cells with elastic light scattering modalities, and harvest of product is streamlined by microcarrier digestion. At volumes above 500 mL, the process is significantly more cost-effective than monolayer culture. Osteogenic cell matrix derived from ihMSCs expanded on GelMA microcarriers exhibited enhanced in vivo bone regenerative capacity when compared to bone morphogenic protein 2, and the ihMSCs exhibited superior immunosuppressive properties in vivo when compared to monolayer-generated ihMSCs. ConclusionsThese results indicate that the cell expansion strategy described here represents a superior approach for efficient generation, monitoring and harvest of therapeutic MSCs and their products.

Injectable photocrosslinking spherical hydrogel-encapsulated targeting peptide-modified engineered exosomes for osteoarthritis therapy

Osteoarthritis (OA) is a common degenerative joint disease urgently needing effective treatments. Bone marrow mesenchymal stromal cell-derived exosomes (Exo) are considered good drug carriers whereas they have limitations such as fast clearance and low retention. This study aimed to overcome the limitations of Exo in drug delivery using multiple strategies. Novel photocrosslinking spherical gelatin methacryloyl hydrogel (GelMA)-encapsulated cartilage affinity WYRGRL (W) peptide-modified engineered Exo were developed for OA treatment and the performance of the engineered Exo (W-Exo@GelMA) loaded with a small inhibitor LRRK2-IN-1 (W-Exo-L@GelMA) was investigated in vitro and in vivo. The W-Exo-L@GelMA showed an effective targeting effect on chondrocytes and a pronounced action on suppressing catabolism and promoting anabolism in vitro. Moreover, W-Exo-L@GelMA remarkably inhibited OA-related inflammation and immune gene expression, rescuing the IL-1β-induced transcriptomic responses. With enhanced retention in the joint, W-Exo-L@GelMA demonstrated superior anti-OA activity and cartilage repair ability in the OA murine model. The therapeutic effect was validated in the cultured human OA cartilage. In conclusion, photocrosslinking spherical hydrogel-encapsulated targeting peptide-modified engineered Exo exhibit notable potential in OA therapy. Engineering Exo by a series of strategies enhanced the targeting ability and retention and cartilage-targeting and Exo-mediated drug delivery may offer a novel strategy for OA treatment.Clinical trial registration: Not applciable.Graphical

Porous Titanium Scaffold: A New Design for Controlled Drug Delivery

Gelatin crosslinking using conventional methods is usually associated with some toxic side effects. In this research, therefore, the vacuum heating method at 10 Pascal and 140°C under different times of 8, 16, and 32 h was used to cross-link strontium-loaded gelatin microparticles with varying degrees obtained by the oil/water mixing method on titanium scaffolds by the dip-coating method to avoid toxicity and also to control the strontium release rate to the surrounding tissue. The possible phases formed on the surface of the porous titanium scaffolds, the gelatin microparticle distribution, gelatin strontium loading, and strontium release were characterized using thin film X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy (SEM), and inductively coupled plasma-mass spectrometer (ICP-MS) machines, respectively. The results indicated that at 600°C, the rutile phase was formed on the surface of the heat-treated titanium scaffolds. Furthermore, strontium was successfully loaded in the spherical gelatin microparticles, and the strontium-loaded gelatin microparticles were distributed uniformly on the surface of the titanium scaffolds, while the rate of the in vitro strontium release decreased by increasing the time of the gelatin microparticle vacuum-heat crosslinking, whereas at the burst release step, the in vitro strontium release rates were around 5, 4.4, and 2.5 ppm/h, for the 8, 16, and 32 h vacuum-heat cross-linked gelatin microparticles, respectively.

Scalable Preparation of Sub-Millimeter Double-Shelled Al2O3 Hollow Spheres and Their Rapid Separation from Wastewater after Adsorption of Congo Red.

Porous double-shelled ceramic hollow spheres (PDSs) have attracted extensive attention due to their high specific surface areas and multifunctional designs. When used in wastewater treatment, millimeter or sub-millimeter spheres can be quickly separated from water by commercial sieves. However, the simple, scalable, and low-cost preparation of sub-millimeter PDSs in the solid phase remains a challenge. Herein, porous PDSs were facilely fabricated via a spheronization process utilizing pseudoboehmite powders and wet gelatin spheres as templates, which broke through the difficulty of preparing PDSs by one-step solid-state synthesis. Treating pseudoboehmite powder with nitric acid can improve the compressive strength of the PDSs. By controlling the rolling time and gelatin concentration of gelatin microspheres, the integrity, shell thickness, and double-shelled spacing of the gelatin microspheres were tuned. When the rolling time was 8–12 min, and the gelatin concentration in gelatin spheres was 250 g/L, and PDSs with a complete double-shelled structure, good mechanical property, and high specific surface area (327.5–509.6 m2/g) were obtained at 600 °C. The adsorption capacities of the PDSs for 100 mg/L Congo red solution (70.7 mg/g) were larger than those of single-shelled hollow spheres (49 mg/g), and larger diameters (608–862 μm) of the PDSs allow them to be rapidly separated from solution by a commercial sieve. This paper provides a facile and scalable method for the preparation of sub-millimeter PDSs and demonstrates their excellent adsorption capacity for Congo red solution.

Nanocracks in nature and industry.

Nanocracks in nature and industry.

Hybrid colloidal gels with tunable elasticity formed by charge-driven assembly between spherical soft nanoparticles and discotic nanosilicates

Colloidal gels based on electrostatic interparticle attractions hold unexploited potential for tailoring their microstructure and properties. Here, we demonstrate that hetero-aggregation between oppositely charged particles with different geometries is a viable strategy for controlling their properties. Specifically, we studied hybrid colloidal gels prepared by the charge-driven assembly of oppositely charged spherical gelatin nanoparticles and two-dimensional (2D) nanosilicates. We show that the asymmetry between the building blocks and the resulting anisotropic interparticle interactions produces a variety of nanostructures and hybrid colloidal gels that exhibit high elasticity at low colloidal volume fractions. Tuning the competition between different attractive interactions in the system by varying the spatial charge heterogeneity on the 2D nanosheets, composition, and ionic strength was found to alter the mechanism of gel formation and their rheological properties. Remarkably, increasing the mass ratio of 2D nanosheets to spherical nanoparticles at a constant total mass fraction affords hybrid gels that exhibit an inverse relationship between elasticity and volume fraction. However, these hybrid gels are easily fluidized and exhibit rapid structural recovery once the stress is removed. These features allow for the engineering of versatile 3D-printable hybrid colloidal gels, whose structure and viscoelastic response are governed by parameters that have not been explored before.

A Biodegradable Magnetic Microrobot Based on Gelatin Methacrylate for Precise Delivery of Stem Cells with Mass Production Capability.

A great deal of research has focused on small-scale robots for biomedical applications and minimally invasive delivery of therapeutics (e.g., cells, drugs, and genes) to a target area. Conventional fabrication methods, such as two-photon polymerization, can be used to build sophisticated micro- and nanorobots, but the long fabrication cycle for a single microrobot has limited its practical use. This study proposes a biodegradable spherical gelatin methacrylate (GelMA) microrobot for mass production in a microfluidic channel. The proposed microrobot is fabricated in a flow-focusing droplet generator by shearing a mixture of GelMA, photoinitiator, and superparamagnetic iron oxide nanoparticles (SPIONs) with a mixture of oil and surfactant. Human nasal turbinate stem cells (hNTSCs) are loaded on the GelMA microrobot, and the hNTSC-loaded microrobot shows precise rolling motion in response to an external rotating magnetic field. The microrobot is enzymatically degraded by collagenase, and released hNTSCs are proliferated and differentiated into neuronal cells. In addition, the feasibility of the GelMA microrobot as a cell therapeutic delivery system is investigated by measuring electrophysiological activity on a multielectrode array. Such a versatile and fully biodegradable microrobot has the potential for targeted stem cell delivery, proliferation, and differentiation for stem cell-based therapy.

Paclitaxel Delivery by Cationic Gelatin Nanoparticles

AbstractBiodegradable polymeric nanoparticles have gained importance since they improve the therapeutic value of various water insoluble drugs and bioactive molecules by improving bioavailability, solubility and retention time. Nanosized drug delivery systems provide enhanced pharmacokinetic and pharmacodynamic control compared to free drugs. In this study, cationic gelatin nanoparticles were first prepared by the two step desolvation method and then their in vitro Paclitaxel (Ptx) delivery ability was evaluated. Resulting nanoparticles were analyzed for their in vitro cytotoxic effect in two different cell lines. The experimental results showed that spherical gelatin nanoparticles had a zeta potential of approximately +15.5 mV and the average size of the particles was 10.3±0.42 nm. Ptx release from gelatin nanoparticles exhibited an initial burst release followed by diffusion of the drug in a sustained manner and finally polymer erosion occured up to 38 days. In vitro cell viabilitiy analysis showed that Ptx loaded gelatin nanoparticles inhibited the growth of A549 and HT29 cells more effectively than the free drug. Based on these findings, it can be stated that cationic gelatin nanoparticles may be a promising therapeutic strategy for the treatment of many cancers.

Fabrication and characterization of osteogenic function of progenitor cell-laden gelatin microcarriers.

Biomaterial-based bone regeneration strategies often include a cellular component to accelerate healing. Modular approaches have the potential for minimally-invasive delivery and the ability to conformally fill complex defects. In this study, spherical gelatin microparticles were fabricated via water-in-oil emulsification and were subsequently crosslinked with genipin. Microparticle diameter depended on impeller geometry, and increased stirring rates consistently produced smaller particles with narrower size distributions. Increasing the concentration of gelatin resulted in larger particles with a broader size distribution. Viscoelastic characterization showed that increased gelatin concentration produced stiffer matrices, though the mechanical properties at lower gelatin concentration were more stable across strain rate. Microparticles of 6.0% wt/vol gelatin were then applied as microcarriers for packed-bed culture of human mesenchymal stromal cells (MSC) at seeding densities of 5.0 × 103 , 2.5 × 104 , or 5.0 × 104 cells/cm2 of surface area, in either control or osteogenic medium. Cell viability was uniformly high (>90%) across seeding densities over 22 days in culture. MSC number stayed approximately constant in the 5.0 × 103 and 2.5 × 104 cells/cm2 samples, while it dropped over time at 5.0 × 104 cells/cm2 . Alkaline phosphatase activity was significantly upregulated in osteogenic conditions relative to controls at day 15, and absolute calcium deposition was strongly induced by days 15 and 22. However, calcium deposition per cell was highest in the lowest cell density, suggesting an inhibitory effect of high cell numbers. These results show that genipin-crosslinked gelatin microcarriers can be reproducibly fabricated and used as microcarriers for progenitor cells, which may have utility in treating large and complex bone defects.

Ionic Strength and Thermal Dual-Responsive Bilayer Hollow Spherical Hydrogel Actuator.

As one of the most promising intelligent materials, polymeric hydrogel actuators could produce reversible shape change upon external stimuli. Although complex shape deformation from 2D to 3D have been achieved, the realization of actuating behavior from 3D to 3D is still a significant challenge. Herein, an effective strategy to develop a novel bilayer hollow spherical hydrogel actuator is proposed. Through immersing a Ca2+ incorporated gelatin core into alginate solution, an ionic-strength-responsive alginate layer will be formed along the gelatin core via alginate-Ca2+ crosslinks, and then another thermo-responsive alginate-poly(2-(dimethylamino)ethyl methacrylate)(Alg-PDMAEMA) layer is introduced to achieve a bilayer hydrogel with ionic strength and temperature dual responsiveness. A hollow hydrogel capsule could be obtained if a spherical gelatin core is applied, and it could produce complex shape deformations from 3D to 3D upon the trigger of ionic strength and temperatures changes. The present work may offer new inspirations for the development of novel intelligent polymeric hydrogel actuators.

Fabrication of a spherical inclusion phantom for validation of magnetic resonance-based magnetic susceptibility imaging

Fabrication of a spherical multi-compartment MRI phantom is demonstrated that can be used to validate magnetic resonance (MR)-based susceptibility imaging reconstruction. The phantom consists of a 10 cm diameter gelatin sphere that encloses multiple smaller gelatin spheres doped with different concentrations of paramagnetic contrast agents. Compared to previous multi-compartment phantoms with cylindrical geometry, the phantom provides the following benefits: (1) no compartmental barrier materials are used that can introduce signal voids and spurious phase; (2) compartmental geometry is reproducible; (3) spherical susceptibility boundaries possess a ground-truth analytical phase solution for easy experimental validation; (4) spherical geometry of the overall phantom eliminates background phase due to air-phantom boundary in any scan orientation. The susceptibility of individual compartments can be controlled independently by doping. During fabrication, formalin cross-linking and water-proof surface coating effectively blocked water diffusion between the compartments to preserve the phantom's integrity. The spherical shapes were realized by molding the inner gel compartments in acrylic spherical shells, 3 cm in diameter, and constructing the whole phantom inside a larger acrylic shell. From gradient echo images obtained at 3T, we verified that the phantom produced phase images in agreement with the theoretical prediction. Factors that limit the agreement include: air bubbles trapped at the gel interfaces, imperfect magnet shimming, and the susceptibility of external materials such as the phantom support hardware. The phantom images were used to validate publicly available codes for quantitative susceptibility mapping. We believe that the proposed phantom can provide a useful testbed for validation of MR phase imaging and MR-based magnetic susceptibility reconstruction.

If I only had a heart

Biomedicine 3D bioprinting is still a fairly new technique that has been limited in terms of resolution and by the materials that can be printed. Lee et al. describe a 3D printing technique to build complex collagen scaffolds for engineering biological tissues (see the Perspective by Dasgupta and Black). Collagen gelation was controlled by modulation of pH and could provide up to 10-micrometer resolution on printing. Cells could be embedded in the collagen or pores could be introduced into the scaffold via embedding of gelatin spheres. The authors demonstrated successful 3D printing of five components of the human heart spanning capillary to full-organ scale, which they validated for tissue and organ function. Science , this issue p. [482][1]; see also p. [446][2] [1]: /lookup/doi/10.1126/science.aav9051 [2]: /lookup/doi/10.1126/science.aay0478

Three-dimensional spherical gelatin bubble-based scaffold improves the myotube formation of H9c2 myoblasts.

Microenvironmental factors including physical and chemical cues can regulate stem cells as well as terminally differentiated cells to modulate their biological function and differentiation. However, one of the physical cues, the substrate's dimensionality, has not been studied extensively. In this study, the flow-focusing method with a microfluidic device was used to generate gelatin bubbles to fabricate highly ordered three-dimensional (3D) scaffolds. Rat H9c2 myoblasts were seeded into the 3D gelatin bubble-based scaffolds and compared to those grown on 2D gelatin-coating substrates to demonstrate the influences of spatial cues on cell behaviors. Relative to cells on the 2D substrates, the H9c2 myoblasts were featured by a good survival and normal mitochondrial activity but slower cell proliferation within the 3D scaffolds. The cortical actin filaments of H9c2 cells were localized close to the cell membrane when cultured on the 2D substrates, while the F-actins distributed uniformly and occupied most of the cell cytoplasm within the 3D scaffolds. H9c2 myoblasts fused as multinuclear myotubes within the 3D scaffolds without any induction but cells cultured on the 2D substrates had a relatively lower fusion index even differentiation medium was provided. Although there was no difference in actin α 1 and myosin heavy chain 1, H9c2 cells had a higher myogenin messenger RNA level in the 3D scaffolds than those of on the 2D substrates. This study reveals that the dimensionality influences differentiation and fusion of myoblasts.

A novel pathway for in situ synthesis of modified gelatin microspheres by silane coupling agents as a bioactive platform

ABSTRACTThis study investigated the fabrication and modification of gelatin microspheres via single emulsion method and silane coupling agents, respectively. Herein, the influence of oil phase and washing procedure on morphology and uniformity of microspheres was evaluated. The results of field emission scanning electron microscopy indicated a positive effect of olive oil on the production of uniform and approximately mono‐size spheres while monodispersity increased after samples were washed under ultrasonication. Investigation of crosslinking degree demonstrated that GPTMS could not show efficiency as high as glutaraldehyde, but the lack of toxicity and inducing bioactive behavior to the microspheres has made them appropriate for bone applications. Moreover, the stability of spheres after 14 days in phosphate buffered saline proved the ability of (3‐glycidyloxypropyl)trimethoxysilane to crosslink gelatin. The presence of silane coupling agents in prepared spheres caused the biomimetic formation of hydroxyapatite after a 14‐day immersion in simulated body fluid as observed by field emission scanning electron microscopy‐energy‐dispersive X‐ray spectroscopy, changes in pH, Fourier transform infrared spectroscopy, X‐ray diffraction, and atomic force microscopy. Adhesion, spreading, and proliferation of L929 cells on the hybrid microspheres corroborated the potential of gelatin spheres for biomedical application. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46739.

Contribution of skin and stone to texture measurements of spherical model fruits.

Consumers gently squeeze fruit to gauge ripeness. Unwittingly, what we perceive while squeezing fruit is not wholly dependent on the texture of the internal flesh. In this work, we have attempted to model how the firmness and breaking force are influenced by the presence of a skin and stones of various size and shape. This has implications in both sensory and instrumental fruit testing.

Improving antioxidant and antimicrobial properties of curcumin by means of encapsulation in gelatin through electrohydrodynamic atomization

Curcumin is a polyphenol with a wide range of biological properties, including antioxidant and antimicrobial activity; however, its use as a food preservative is limited because of its insolubility in water. The present work is an attempt to overcome this problem by means of matrix encapsulation of curcumin in gelatin through electrohydrodynamic atomization (EHDA). Compact spherical gelatin particles ranging from few nanometers to more than 1 μm in diameter loaded with 10% (w/w) curcumin were successfully obtained, and the encapsulation efficiency being close to 100%. Fluorescence microscopy indicated that the curcumin was homogeneously distributed in the particles, while modulated differential scanning calorimetry analysis showed that the curcumin was intimately mixed with gelatin polymer, and a complete loss of curcumin crystallinity was observed in the solid dispersion. Furthermore, the UV–visible spectrum of dissolved/dispersed particles showed a shift of the maximum absorbance of curcumin toward lower wavelengths, indicating gelatin–curcumin interactions. The water solubility of curcumin increased 38.6-fold after it had been encapsulated in gelatin microparticles. With regard to antioxidant properties, they increased when blended with gelatin compared with commercial curcumin powder. Although antibacterial activity of raw curcumin was negligible at concentrations up to 100 mg/ml, gelatin-encapsulated curcumin at 4 mg/ml reduced the microbial population by 2.08, 1.67, 2.70, and 2.18 log counts (CFU/ml) for L. monocytogenes, S. enterica, S. aureus, and E. coli, respectively. Accordingly, it was proved that encapsulation of curcumin in gelatin particles by EHDA greatly improved its antioxidant and antimicrobial properties, thus broadening its potential use as a food preservative.

Contact Stresses in Gelatin Spheres Under Compressive Die Loading

AbstractGelatin spheres have been used to model stress/strain behavior of spherical foods (e.g., fruits) during compression testing. Photoelasticity reveals differences in stress distribution within gelatin spheres depending on the way in which the spheres are supported. Moreover, these methods of support appear to result in differences in the elastic modulus at higher levels of applied stress. If differences in the manner of support of model foods under compression result in variation in the stress distribution and moduli, then thought must be given to the way in which real foods are supported during quality and texture testing.Practical ApplicationsThe common practice of supporting materials on a plane surface during texture testing is brought into question due to differences in contact stress when supported in this manner as opposed contouring the object in some kind of supporting mould. Soft gels which deform under gravity maybe tested with a texturometer if immersed in a liquid that provides buoyancy.

Sensitively Photoelastic Biocompatible Gelatin Spheres for Investigation of Locomotion in Granular Media

We present a method for measuring forces in granular media experiments using photoelastic gelatin spheres, which is applicable for investigating the forces generated by organisms moving through noncohesive granular materials. We describe how to fabricate gelatin spheres with appropriate characteristics for high-sensitivity photoelastic measurements. We present a calibration methodology to relate photoelastic signal to force applied to the spheres, and evaluate the photoelastic performance of gelatin spheres as a function of gelatin concentration. The spheres can be used across a range of salinities, allowing investigation of freshwater and marine organisms. We show that photoelastic gelatin spheres can detect forces as small as 1 μN, and quantitatively measure forces with up to 60 μN precision. We provide a proof-of-principle experiment in which the forces exerted by an earthworm in a granular environment are measured.