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Evapoporometry (EP) is a relatively new technique for measuring the pore-size distribution (PSD) of membranes, which is a key determinant of properties such as the permeability and rejection. EP is based on determining the pore diameter from the evaporation rate of a volatile wetting liquid that initially saturates the membrane pores using the Kelvin equation. Heretofore the pore diameter range measureable via EP was approximately from 4 to 150 nm. The lower limit is because the classical Kelvin equation breaks down at small pore diameters, whereas the upper limit is because the vapor pressure depression and corresponding evaporation rate associated with large pores becomes too small to be accurately determined. The goal of this study was to extend the upper pore diameter limit for EP characterization. The classical Kelvin equation indicates that the vapor pressure depression can be increased by choosing volatile wetting liquids with a larger surface tension and molar volume, thereby allowing for larger pores to be measured accurately. In this study a range of volatile wetting liquids were explored that would permit extending the range of EP. An optimal choice was 1-butanol that was shown to permit accurately characterizing the PSD of an Anopore membrane having a nominal pore diameter of 200 nm, which was not possible hitherto using EP. NRF (Natl Research Foundation, S’pore) MOE (Min. of Education, S’pore) EDB (Economic Devt. Board, S’pore)

Generating porous topographic substrates, by mimicking the native extracellular matrix (ECM) to promote the regeneration of damaged bone tissues, is a challenging process. Generally, scaffolds developed for bone tissue regeneration support bone cell growth and induce bone-forming cells by natural proteins and growth factors. Limitations are often associated with these approaches such as improper scaffold stability, and insufficient cell adhesion, proliferation, differentiation, and mineralization with less growth factor expression. Therefore, the use of engineered nanoparticles has been rapidly increasing in bone tissue engineering (BTE) applications. The electrospray technique is advantageous over other conventional methods as it generates nanomaterials of particle sizes in the micro/nanoscale range. The size and charge of the particles are controlled by regulating the polymer solution flow rate and electric voltage. The unique properties of nanoparticles such as large surface area-to-volume ratio, small size, and higher reactivity make them promising candidates in the field of biomedical engineering. These nanomaterials are extensively used as therapeutic agents and for drug delivery, mimicking ECM, and restoring and improving the functions of damaged organs. The controlled and sustained release of encapsulated drugs, proteins, vaccines, growth factors, cells, and nucleotides from nanoparticles has been well developed in nanomedicine. This review provides an insight into the preparation of nanoparticles by electrospraying technique and illustrates the use of nanoparticles in drug delivery for promoting bone tissue regeneration. MOE (Min. of Education, S’pore) Accepted version

Collagen has been used extensively in tissue engineering applications. However, the source of collagen has been primarily bovine and porcine. In view of the potential risk of zoonotic diseases and religious constraints associated with bovine and porcine collagen, fish collagen was examined as an alternative. The aim of this study is to use tilapia fish collagen to develop a cross-linked electrospun membrane to be used as a barrier membrane in guided bone regeneration. As there is limited data available on the cytotoxicity and immunogenicity of cross-linked tilapia collagen, in vitro and in vivo tests were performed to evaluate this in comparison to the commercially available Bio-Gide® membrane. In this study, collagen was extracted and purified from tilapia skin and electrospun into a nanofibrous membrane. The resultant membrane was cross-linked to obtain a cross-linked electrospun tilapia collagen (CETC) membrane, which was characterized by scanning electron microscopy (SEM), differential scanning calori...

Hybrid biocomposite nanofibrous structures that mimics native extracellular matrix have been extensively applied for bone tissue engineering (BTE) due to their potential in efficiently inducing cellular response for the secretion of extracellular matrix (ECM). This study performed fabrication of uniform porous polycaprolactone (PCL), polycaprolactone/silk fibroin (PCL/SF), polycaprolactone/silk fibroin/minocycline hydrochloride (PCL/SF/MH), polycaprolactone/collagen (PCL/COL), and polycaprolactone/collagen/minocycline hydrochloride (PCL/COL/MH) biocomposites nanofibrous scaffolds by electrospinning, for comparing their properties to use in bone tissue regeneration. Field emission scanning electron microscopy (FESEM) images of fabricated nanofibrous scaffolds revealed porous, beadless, uniform fibers of diameter in the range of 147.13 ± 28.02 to 176.53 ± 22.34 nm and porosity around 82–93 %. Adipose-derived stem cells (ADSCs) considered as the novel cell therapeutics were cultured on these electrospun fibrous scaffolds to undergo osteogenic differentiation for BTE. The cell morphology, proliferation, and interactions were analyzed by CMFDA dye extrusion, MTS assay, and FESEM analysis, respectively. Differentiation of ADSCs into osteogenesis was determined by alkaline phosphatase activity, mineralization by alizarin red staining, and osteogenic protein expression by immunofluorescence analysis. The results demonstrated that the addition of SF and MH to PCL-based scaffolds improved the mechanical stability, interconnected pores, and surface roughness of the scaffolds initiating heightened biological functions such as ADSCs adhesion, proliferation, differentiation, and mineralization into osteogenesis for bone tissue regeneration. Globally, the rate of bone defects or trauma has been trending upwards and is predicted to rapidly increase by 2020. This is mainly due to the lack of physical activity, age, and increased obese populations. A basic understanding of the morphological characteristics and biological functions of mineralized bone tissue substrates is required for effective clinical treatments. The engineered bone tissue substrates have been potentially used as an alternative to the traditional bone grafts. However using these engineered bone substrates in clinical practices has certain limitations. These limitations can be overcome by the inclusion of natural polymers, growth factors, and stem cells. The current study demonstrates the addition of silk fibroin and minocycline hydrochloride to polycaprolactone-based scaffolds potentially enhanced adipose-derived stem cells differentiation into osteogenesis.

Mimicking hybrid extracellular matrix is one of the major challenges in bone tissue engineering. Biocomposite micro/nanoparticle of polycaprolactone (PCL), silk fibroin (SF), ascorbic acid (AA) and dexamethasone (DM) were fabricated by the electrospraying methods in order to generate an improved osteogenic environment for the proliferation and differentiation of adipose derived stem cells (ADSCs) into osteogenesis. Fabricated electrosprayed micro/nanoparticle was characterized for particle morphology, hydrophilicity, porosity and FTIR analysis for bone tissue regeneration. FESEM micrographs of the nanoparticles revealed porous, fibreless, uniform particles with particle diameter in the range of 720 ± 1.8 nm - 3.5 ± 4.2 µm. The drug release profile indicates that the sustained release of dexamethasone up to 10 days and degradation of nanoparticles around 13-20% after 60 days. ADSCs were cultured on these nanoparticles and were induced to undergo osteogenic differentiation in the presence of AA/DM. The cells morphology, proliferation and interaction were analysed by CMFDA dye extraction method, MTS assay and FESEM analysis respectively.ADSCs differentiation into osteogenesis was confirmed using alkaline phosphatase activity and mineralisation by Alizarin Red staining. The significance of AA and DM biomolecules initiates particular biological functions for the proliferation of ADSCs and differentiation into osteogenic lineages. The obtained results proved that the biocomposite PCL/SF/AA/DM micro/nanoparticle stimulated osteogenic differentiation and mineralisation of ADSCs for bone tissue regeneration. MOE (Min. of Education, S’pore) Published version