S.F.Akhtarianfar Akhtarian

Bio: S.F.Akhtarianfar Akhtarian is an academic researcher from University of Kashan. The author has contributed to research in topics: Molecularly imprinted polymer & Materials science. The author has an hindex of 1, co-authored 1 publications receiving 31 citations.

Metal Microwires Functionalized with Cell-Imprinted Polymer for Capturing Bacteria in Water

Abstract: Molecularly imprinted polymers (MIPs) and cell-imprinter polymers (CIPs) have emerged as synthetic recognition elements in biomimetic sensors. In this paper, we have conducted a parametric study to optimize a bulk polymerization methodology for uniform functionalization of stainless steel microwires (MWs) with CIPs comprising single to fourplex combinations of functional monomers (FMs). MWs are widely used in biosensors, and their functionalization with single-FM MIPs has been demonstrated. Complex MIPs comprising multiple FMs have shown enhanced selectivity toward microorganisms, but their coating on MWs has yet to be shown. Moreover, imprinting microorganisms into these coatings has not been reported. In our studies, solvent, FM, cross-linker-to-FM ratio, polymerization temperature, and time were found to significantly influence the thickness and uniformity of CIP coatings on MWs. Reproducible CIP coatings with a thickness of 2.2 ± 0.4 μm, imprinted with E. coli OP50 as the template, were achieved. E. coli rebinding assays demonstrated a 76 ± 10% capture efficiency in a suspension with an initial bacteria count of 104 CFU/mL, using a 3 cm long CIP-MW with an optimized fourplex CIP composition, while the capture efficiency obtained by using a single-monomer CIP composition was 30 ± 5%. Our results indicated a higher binding capacity of fourplex CIP-MWs to target bacteria, while nonsignificant binding was obtained using single-monomer CIP-MWs. The addition of N-vinylpyrrolidone significantly increased the binding performance due to its hydrophobic–hydrophilic functional groups interacting with counterparts on the surface of bacterial cells. The developed CIP-MWs can be integrated with microfluidic sensing systems as low-cost and stable working electrodes for future transduction of CIP-target binding events to an electrical read-out in CIP-based electrochemical biomimetic sensors.

Hydroxyapatite nanoparticles coating on Ti-6Al-4V substrate using plasma spray method

Abstract: ABSTRACT In this research, hydroxyapatite powder particles were coated on a Ti-6Al-4V alloy substrate by the plasma spraying method to create bone implants by benefitting from titanium's mechanical properties and hydroxyapatite's biological properties. Hydroxyapatite prepared by the plasma spraying method suffers from decomposition, formation of other calcium phosphate phases, weak adhesion to the substrate, and microcrack formation in the coating due to residual stresses initiated by the high temperature of the coating process. To improve the hydroxyapatite coating properties, the Ti-6Al-4V alloy was preheated, and then hydroxyapatite coating took place. The results showed that residual stress in the interface decreased, and adhesion improved by preheating the substrate. However, formation of an amorphous phase on coating was observed, resulting in a higher dissolution rate in the biological environment and weak mechanical properties compared to crystalline hydroxyapatite. Experimental results showed that heat treatment after the coating process decreased the amount of this amorphous phase and heightened the crystallinity of the coating by up to more than 60%.

Influence of Atomic Hydrogen, Band Bending, and Defects in the Top Few Nanometers of Hydrothermally Prepared Zinc Oxide Nanorods

Abstract: We report on the surface, sub-surface (top few nanometers) and bulk properties of hydrothermally grown zinc oxide (ZnO) nanorods (NRs) prior to and after hydrogen treatment. Upon treating with atomic hydrogen (H*), upward and downward band bending is observed depending on the availability of molecular H2O within the structure of the NRs. In the absence of H2O, the H* treatment demonstrated a cleaning effect of the nanorods, leading to a 0.51 eV upward band bending. In addition, enhancement in the intensity of room temperature photoluminescence (PL) signals due to the creation of new surface defects could be observed. The defects enhanced the visible light activity of the ZnO NRs which were subsequently used to photocatalytically degrade aqueous phenol under simulated sunlight. On the contrary, in the presence of H2O, H* treatment created an electronic accumulation layer inducing downward band bending of 0.45 eV (~1/7th of the bulk ZnO band gap) along with the weakening of the defect signals as observed from room temperature photoluminescence spectra. The results suggest a plausible way of tailoring the band bending and defects of the ZnO NRs through control of H2O/H* species.