Providing magnetite nanoparticles with saccharide coatings has been found to significantly increase the interactions of the nanoparticles with cells. Glucose (Glc) or N-acetylglucosamine (GlcNAc) coated magnetic nanoparticles (MNPs) were used to magnetically label 3T3 fibroblast cells, and the response of the labelled cells to external magnetic fields was studied. It was found that cells incubated with Glc- or GlcNAc-coated nanoparticles were much more likely to move towards an external magnet than those incubated with uncoated nanoparticles. Furthermore, cells in suspension moved much faster than those in contact with the surface of polystyrene well plates, with stronger magnets increasing the speed of movement. Cells that were adhering to the floor of the cell culture well and did not move in the x-y plane could still be rotated about the z-axis by moving the external magnet around the cell.

The antibacterial properties are useful to restrain inflammatory response caused by bacterial infection after implantation. The composites of hydroxyapatite (HAp) and silver nano-dots, silver oxide or silver phosphate have been investigated; however there are still some disadvantage in sintering; 1) silver nano-dots grow large, and are not homogenously distributed, 2) silver nano-dots melt and remove, and 3) silver phosphate and silver oxide formed exhibit higher solubility than metal silver. In this study, the distribution of silver nano-dots in HAp microparticles sintered was controlled at grain boundary with a modified silver mirror reaction as a novel route. HAp microparticles adsorbed formaldehyde by a vapor deposition method were soaked in an ammoniacal silver nitrate solution and were then sintered. There was a single phase of HAp including metal silver at 6.4 wt% even after sintering. The silver nano-dots were homogeneously distributed inside the microparticles. The release profiles of silver ions in phosphate buffer saline were compared with a reference; the HAp microparticles were soaked into silver nitrate solution and were then sintered. The distribution of silver in the reference was not homogeneous and large silver microparticles were grown outside the particles at 6.3wt%. The elution amount of silver ions from the microparticles at 12 hours was one-eighteenth of that from the reference. These results suggest that the HAp microparticles including silver nano-dots at grain boundary will be suitable for a long-term antibacterial material.

The development of biodegradable polymeric nanofiber scaffolds for a potential effort to repair injured nerve cells is of great interest in nerve tissue engineering applications. Poly (L-lactic acid) (PLLA) has been widely used in nerve conduit studies due to its biocompatibility, easily shaped properties and degradation to low toxic lactic acid. However, its hydrophobicity and lack of binding sites for cellular activities restricts its use as implants. In this regard, this study involves the incorporation of graphene oxide (GO) into PLLA nanofibers for enhancing mechanical properties, electrical conductivity and hydrophilicity of PLLA to make it suitable for a potential peripheral nerve regeneration application. For this purpose, PLLA and PLLA/GO nanofibers were prepared via electrospinning. The processing parameters and solution parameters were optimized to adjust physical and mechanical properties of nanofiber in terms of size, porosity and biologically active affinity for cellular interaction. The morphology and composition of the developed electrospun fibers were characterized via, Scanning Electron Microscopy (SEM), Raman Spectroscopy, tensile testing and contact angle measurements. The morphological results showed that using chloroform/DMF ratio of 8/2 for 7wt% PLLA led to the formation of bead free and thinner PLLA fibers than fibers produced from other concentration of PLLA. Moreover, the addition of the GO resulted in decrease of the average diameter of PLLA fibers from 828 nm to 490 nm and the thinnest nanofiber structure was obtained by addition of 10 v/v % GO. The sonication time of GO highly enhanced the porosity of the nanofibers, namely the porosity of the nanofibers increased with increasing sonication time. Raman Spectroscopy exhibits peaks at bands of 1775, 873 and 1455 cm-1 that are attributed to C=O stretching, C-COO stretching and CH3 asymmetric deformation respectively for PLLA and 1379 and 1599 cm-1 which represent structural imperfections and sp2 domain of carbon atoms respectively for GO. Hence, Raman peaks confirmed that GO was mixed in PLLA nanofibers. The incorporation of GO significantly improved the tensile strength from 2.25 MPa of pure PLLA to 8.13 MPa, 10.44 MPa and 12.93 MPa with 5, 7.5 and 10 v/v% of GO addition, respectively. The results revealed that the addition of GO led to enhanced chemical and physical properties of fibers which is promising for nerve regeneration applications.

Magnetic bioseparation is an important area of biotechnology. Various techniques are used with a wide range of possible applications in bioscience research. Magnetic micro- or nanospheres can be functionalized with appropriate ligands, such as antibodies, with a high affinity to the target, like cells, bacteria or DNA/RNA. In order to realize magnets with efficient separation capabilities, it is important to have a strong force FM acting on the magnetic bodies. FM is proportional to the product of the magnetic field and the field gradient. Many permanent magnets on the market have large magnetic fields, but relatively weak field gradients. GIAMAG magnets have unique and patented designs that produce both very large magnetic fields and high field gradients, resulting in the most forceful magnetic separators available on the market.

In today’s technology, organ transplantation is found very challenging as it is not easy to find the right donor organ in a short period of time. In the last several decades, tissue engineering was rapidly developed to be used as an alternative approach to the organ transplantation. Tissue engineering aims to regenerate the tissues and also organs to help patients who waits for the organ transplantation. Recent research showed that in order to regenerate the tissues, cells must be seeded onto the 3D artificial laboratory fabricated matrices called scaffolds. If cells show healthy growth within the scaffolds, they can be implanted to the injured tissue to do the regeneration. One of the biggest limitation that reduces the success rate of tissue regeneration is the fabrication of accurate thick 3D scaffolds. In this research “maskless photolithography” was used to fabricate the scaffolds. Experiment setup consist of digital micro-mirror devices (DMD) (Texas Instruments, DLi4120), optical lens sets, UV light source (DYMAX, BlueWave 200) and PEGDA which is a liquid form photo-curable solution. In this method, scaffolds are fabricated in layer-by-layer fashion to control the interior architecture of the scaffolds. Working principles of the maskless photolithography is, first layer shape is designed with AutoCAD and the designed image is uploaded to the DMD as a bitmap file. DMD consists of hundreds of tiny micro-mirrors. When the UV light is turned on and irradiated the DMD, depending on the micro-mirrors’ angles, UV light is selectively reflected to the low percentage Polyethylene (glycol) Diacrylate (PEGDA) photo-curable solution. When UV light penetrates into the PEGDA, only the illuminated part is solidified and non-illuminated area still remains in the liquid phase. In this research, scaffolds were fabricated in three layers. First layer and the last layer are solid layers and y-shape open structure was sandwiched between these layers. After the first layer is fabricated with DMD, a “y-shape” structure was fabricated with the 3D printer by using the dissolvable filament. Then, it was placed onto the first solid layer and covered with fresh high percentage PEGDA solution. UV light was reflected to the PEGDA solution and solidified to make the second and third layers. After the scaffold was fabricated, it is dipped into the limonene solution to dissolve the y-shape away. Our results show that thick scaffolds can be fabricated in layer-by-layer fashion with “maskless photolithography”. Since the UV light is stable and does not move onto the PEGDA, entire scaffold can be fabricated in one single UV shot which makes the process faster than the current fabrication techniques.

Hydrogels have been widely used in many applications from tissue engineering to drug delivery systems. For both tissue engineering and drug delivery, the mechanical properties are important because they would affect cell-materials interactions and injectability of drugs encapsulated in hydrogel carriers. Therefore, it is important to study the mechanical properties of these hydrogels, particularly at physiological temperature (37°C). This study adopted strain sweep and frequency sweep rotational rheological tests to investigate the rheological characteristics of various tissue engineering relevant hydrogels with different concentrations at 37°C. These hydrogels include alginate, RGD-alginate, and copolymerized collagen/alginate/fibrin. It has revealed that the addition of RGD has negligible effect on the elastic modulus and viscosity of alginate. Alginate gels have demonstrated shear thinning behavior which indicates that they are suitable candidates as carriers for cells or drug delivery. The addition of collagen and fibrin would reinforce the mechanical properties of alginate which makes it a strong scaffold material.

Materials processing and additive manufacturing afford exciting opportunities in biomedical research, including the study of cell-material interactions. However, some of the most efficient materials for microfabrication are not wholly suitable for biological applications, require extensive post-processing or exhibit high mechanical stiffness that limits the range of applications. Conversely, materials exhibiting high cytocompatibility and low stiffness require long processing times with typically decreased spatial resolution of features. Here, we investigated the use of hexanediol diacrylate (HDDA), a classic and efficient polymer for stereolithography, for oligodendrocyte progenitor cell (OPC) culture. We developed composite HDDA-polyethylene glycol acrylate hydrogels that exhibited high biocompatibility, mechanical stiffness in the range of muscle tissue, and high printing efficiency at ∼5 μm resolution.