No abstract

Nanofibers and nanomaterials are potentially recent additions to materials in relation to tissue engineering (TE). TE is the regeneration of biological tissues through the use of cells, with the aid of supporting structures and biomolecules. Mimicking architecture of extracellular matrix is one of the challenges for TE. Biodegradable biopolymer nanofibers with controlled surface and internal molecular structures can be electrospun into mats with specific fiber arrangement and structural integrity for drug delivery and TE applications. The polymeric materials are widely accepted because of their ease of processability and amenability to provide a large variety of cost-effective materials, which help to enhance the comfort and quality of life in modern biomedical and industrial society. Today, nanotechnology and nanoscience approaches to scaffold design and functionalization are beginning to expand the market for drug delivery and TE is forming the basis for highly profitable niche within the industry. This review describes recent advances for fabrication of nanofiber scaffolds and interaction of cells in TE.

Bone defects represent a medical and socioeconomic challenge. Engineering bioartificial bone tissues may help to solve problems related to donor site morbidity and size limitations. Nanofibrous scaffolds were electrospun into a blend of synthetic biodegradable polycaprolactone (PCL) with hydroxyapatite (HA) and natural polymer gelatin (Gel) at a ratio of 1:1:2 (PCL/HA/Gel) compared to PCL (9%), PCL/HA (1:1), and PCL/Gel (1:2) nanofibers. These fiber diameters were around 411 Ϯ 158 to 856 Ϯ 157 nm, and the pore size and porosity around 5-35 mm and 76-93%, respectively. The interconnecting porous structure of the nanofibrous scaffolds provides large surface area for cell attachment and sufficient space for nutrient transportation. The tensile property of composite nanofibrous scaffold (PCL/HA/Gel) was highly flexible and allows penetrating osteoblasts inside the scaffolds for bone tissue regeneration. Fourier transform infrared analysis showed that the composite nanofiber contains an amino group, a phosphate group, and carboxyl groups for inducing proliferation and mineralization of osteoblasts for in vitro bone formation. The cell proliferation (88%), alkaline phosphatase activity (77%), and mineralization (66%) of osteoblasts were significantly (P < 0.001) increased in composite nanofibrous scaffold compared to PCL nanofibrous scaffolds. Field emission scanning electron microscopic images showed that the composite nanofibers supported the proliferation and mineralization of osteoblast cells. These results show that the fabrication of electrospun PCL/ HA/Gel composite nanofibrous scaffolds has potential for the proliferation and mineralization of osteoblasts for bone regeneration.

Regeneration of fractured or diseased bones is the challenge faced by current technologies in tissue engineering. The major solid components of human bone consist of collagen and hydroxyapatite. Collagen (Col) and hydroxyapatite (HA) have potential in mimicking natural extracellular matrix and replacing diseased skeletal bones. More attention has been focused on HA because of its crystallographic structure similar to inorganic compound found in natural bone and extensively investigated due to its excellent biocompatibility, bioactivity and osteoconductivity properties. In the present study, electrospun nanofibrous scaffolds are fabricated with collagen (80 mg/ml) and Col/HA (1:1). The diameter of the collagen nanofibers is around 265 +/- 0.64 nm and Col/HA nanofibers are 293 +/- 1.45 nm. The crystalline HA (29 +/- 7.5 nm) loaded into the collagen nanofibers are embedded within nanofibrous matrix of the scaffolds. Osteoblasts cultured on both scaffolds and show insignificant level of proliferation but mineralization was significantly (p < 0.001) increased to 56% in Col/HA nanofibrous scaffolds compared to collagen. Energy dispersive X-ray analysis (EDX) spectroscopy results proved the presence of higher level of calcium and phosphorous in Col/HA nanocomposites than collagen nanofibrous scaffolds grown osteoblasts. The results of the present study suggested that the designed electrospun nanofibrous scaffold (Col/HA) have potential biomaterial for bone tissue engineering.

Biocompatible polycaprolactone (PCL) and hydroxyapatite (HA) were fabricated into nanofibrous scaffolds for the mineralization of osteoblasts in bone tissue engineering. PCL and PCL/HA nanofibrous surface were modified using oxygen plasma treatment and showing 0 degrees contact angle for the adhesion and mineralization of osteoblast cells. The fiber diameter, pore size and porosity of nanofibrous scaffolds were estimated to be 220-625 nm, 3-20 microm, and 87-92% respectively. The ultimate tensile strength of PCL was about 3.37 MPa and PCL/HA was 1.07 MPa to withstand the long term culture of osteoblasts on nanofibrous scaffolds. Human fetal osteoblast cells (hFOB) were cultured on PCL and PCL/HA surface modified and unmodified nanofibrous scaffolds. The osteoblast proliferation rate was significantly (p < 0.001) increased in surface-modified nanofibrous scaffolds. FESEM showed normal phenotypic cell morphology and mineralization occurred in PCL/HA nanofibrous scaffolds, HA acting as a chelating agent for the mineralization of osteoblast to form bone like apatite for bone tissue engineering. EDX and Alizarin Red-S staining indicated mineral Ca(2+) and phosphorous deposited on the surface of osteoblast cells. The mineralization was significantly increased in PCL/HA-modified nanofibrous scaffolds and appeared as a mineral nodule synthesized by osteoblasts similar to apatite of the natural bone. The present study indicated that the PCL/HA surface-modified nanofibrous scaffolds are potential for the mineralization of osteoblast for bone tissue engineering.