Pedram Azari

Polymethacrylate coated electrospun PHB fibers: An exquisite outlook for fabrication of paper-based biosensors

Electrospun polyhydroxybutyrate (PHB) fibers were dip-coated by polymethyl methacrylate-co-methacrylic acid, poly(MMA-co-MAA), which was synthesized in different molar ratios of the monomers via free-radical polymerization. Fabricated platfrom was employed for immobilization of the dengue antibody and subsequent detection of dengue enveloped virus in enzyme-linked immunosorbent assay (ELISA). There is a major advantage for combination of electrospun fibers and copolymers. Fiber structre of electrospun PHB provides large specific surface area available for biomolecular interaction. In addition, polymer coated parts of the platform inherited the premanent presence of surface carboxyl (-COOH) groups from MAA segments of the copolymer which can be effectively used for covalent and physical protein immobilization. By tuning the concentration of MAA monomers in polymerization reaction the concentration of surface -COOH groups can be carefully controlled. Therefore two different techniques have been used for immobilization of the dengue antibody aimed for dengue detection: physical attachment of dengue antibodies to the surface and covalent immobilization of antibodies through carbodiimide chemistry. In that perspective, several different characterization techniques were employed to investigate the new polymeric fiber platform such as scanning electron microscopy (SEM), atomic force microscopy (AFM), water contact angle (WCA) measurement and UV-vis titration. Regardless of the immobilization techniques, substantially higher signal intensity was recorded from developed platform in comparison to the conventional ELISA assay.

Differential osteogenic potential of human adipose‐derived stem cells co‐cultured with human osteoblasts on polymeric microfiber scaffolds

The osteogenic potential of human adipose-derived stem cells (HADSCs) co-cultured with human osteoblasts (HOBs) using selected HADSCs/HOBs ratios of 1:1, 2:1, and 1:2, respectively, is evaluated. The HADSCs/HOBs were seeded on electrospun three-dimensional poly[(R)-3-hydroxybutyric acid] (PHB) blended with bovine-derived hydroxyapatite (BHA). Monocultures of HADSCs and HOBs were used as control groups. The effects of PHB-BHA scaffold on cell proliferation and cell morphology were assessed by AlamarBlue assay and field emission scanning electron microscopy. Cell differentiation, cell mineralization, and osteogenic-related gene expression of co-culture HADSCs/HOBs were examined by alkaline phosphatase (ALP) assay, alizarin Red S assay, and quantitative real time PCR, respectively. The results showed that co-culture of HADSCs/HOBs, 1:1 grown into PHB-BHA promoted better cell adhesion, displayed a significant higher cell proliferation, higher production of ALP, extracellular mineralization and osteogenic-related gene expression of run-related transcription factor, bone sialoprotein, osteopontin, and osteocalcin compared to other co-culture groups. This result also suggests that the use of electrospun PHB-BHA in a co-culture HADSCs/HOBs system may serve as promising approach to facilitate osteogenic differentiation activity of HADSCs through direct cell-to-cell contact with HOBs.

Electrospun biopolyesters as drug screening platforms for corneal keratocytes

In vitro drug screening techniques provide rapid and easy to analyze data, while saving a lot of animals from being sacrificed. An important part of any in vitro drug screening platform is a biomaterial which promotes cell growth and proliferation. The potential of electrospun scaffolds made of polyhydroxybutyrate (PHB), poly (3-hydroxybutyric acid-co-3-hydroxyvaleric acid) (PHBV), and polycaprolactone (PCL) were studied to serve as drug screening platform for corneal keratocyte tissues. The results showed that the proliferation rate was slightly higher for PCL and PHBV on day 7. Gene expression results showed that PCL was the best in maintaining keratocyte genes. GRAPHICAL ABSTRACT

Improved processability of electrospun poly[(R)-3- hydroxybutyric acid] through blending with medium- chain length poly(3-hydroxyalkanoates) produced by Pseudomonas putida from oleic acid

Abstract Polyhydroxyalkanoates are bacterial biopolyesters having good biocompatibility and biodegradability. Poly[(R)-3-hydroxybutyric acid] is the least expensive/costly and most easily available member of this family. However, poly[(R)-3-hydroxybutyric acid] is very brittle because of its high crystallinity. Its poor processability poses limitations on its application. Blending of this material with another amorphous flexible polymer has been a common practice. In this research, we have improved the properties of poly[(R)-3-hydroxybutyric acid] through blending with a palm oil-based medium-chain length polyhydroxyalkanoate. Solution blending was carried out at four different ratios to produce electrospun fibres. As expected, the addition of medium-chain length polyhydroxyalkanoate has reduced the brittleness of poly[(R)-3-hydroxybutyric acid], through reducing the crystallinity. In addition, it has enabled the reduction of the diameter of the electrospun fibres and shifted it from micrometre towards nanometres, which can improve its porosity and permeability to make it a potential material in biomedical applications.

Polymethacrylate Coated Electrospun PHB Fibers as a Functionalized Platform for Bio-Diagnostics: Confirmation Analysis on the Presence of Immobilized IgG Antibodies against Dengue Virus

In this article, a combination of far field electrospinning (FFES) and free-radical polymerization has been used to create a unique platform for protein immobilization via the physical attachment of biomolecules to the surface of the fiber mats. The large specific surface area of the fibers with its tailored chemistry provides a desirable platform for effective analyte-surface interaction. The detailed analysis of protein immobilization on a newly developed bio-receptive surface plays a vital role to gauge its advantages in bio-diagnostic applications. We relied on scanning electron microscopy (SEM), diameter range analysis, and X-ray photoelectron spectroscopy (XPS), along with thermal gravimetric analysis (TGA), water-in-air contact angle analysis (WCA), Fourier transform infrared spectroscopy (FTIR), and atomic force microscopy (AFM) to study our developed platforms and to provide valuable information regarding the presence of biomolecular entities on the surface. Detailed analyses of the fiber mats before and after antibody immobilization have shown obvious changes on the surface of the bioreceptive surface including: (i) an additional peak corresponding to the presence of an antibody in TGA analysis; (ii) extra FTIR peaks corresponding to the presence of antibodies on the coated fiber platforms; and (iii) a clear alteration in surface roughness recorded by AFM analysis. Confirmation analyses on protein immobilization are of great importance as they underlay substantial grounds for various biosensing applications.

An in-vitro study on the proliferative potential of rat bone marrow stem cells on electrospun fibrous polycaprolactone scaffolds containing micro-hydroxyapatite particles

Abstract Hydroxyapatite has a chemical composition that closely resembles the mineral phase of natural hard tissues, making it a good material for use as a bone scaffold. Previous studies have demonstrated that the use of electrospun nanofibres that contain synthetic hydroxyapatite aids in bone regeneration. In this study, composite scaffolds of polycaprolactone and bovine-derived hydroxyapatite were produced by mixing bovine-derived hydroxyapatite powder into polycaprolactone solution, followed by electrospinning. Field emission scanning electron microscopy images show that the scaffolds contained an interconnected spheroidal porous network. Four groups of scaffolds containing different weight percentages of bovine-derived hydroxyapatite (0, 10, 30 and 50%) were prepared. The scaffolds were characterised by infrared spectroscopy and field emission scanning electron microscopy which was used to observe cell attachment to the scaffolds as well.

Electrospin-coating of nitrocellulose membrane enhances sensitivity in nucleic acid-based lateral flow assay

Point-of-care biosensors are important tools developed to aid medical diagnosis and testing, food safety and environmental monitoring. Paper-based biosensors, especially nucleic acid-based lateral flow assays (LFA), are affordable, simple to produce and easy to use in remote settings. However, the sensitivity of such assays to infectious diseases has always been a restrictive challenge. Here, we have successfully electrospun polycaprolactone (PCL) on nitrocellulose (NC) membrane to form a hydrophobic coating to reduce the flow rate and increase the interaction rate between the targets and gold nanoparticles-detecting probes conjugates, resulting in the binding of more complexes to the capture probes. With this approach, the sensitivity of the PCL electrospin-coated test strip has been increased by approximately ten-fold as compared to the unmodified test strip. As a proof of concept, this approach holds great potential for sensitive detection of targets at point-of-care testing.