ORCID Profile
0000-0003-3872-2933
Current Organisations
Scion
,
University of Aberdeen
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Publisher: Royal Society of Chemistry (RSC)
Date: 2011
DOI: 10.1039/C0SM01360A
Publisher: Oxford University Press (OUP)
Date: 04-2009
DOI: 10.1111/J.1365-2672.2008.04090.X
Abstract: Preconditioning of stainless steel with aqueous cod muscle extract significantly impedes subsequent bacterial adhesion most likely due to repelling effects of fish tropomyosin. The purpose of this study was to determine if other food conditioning films decrease or enhance bacterial adhesion to stainless steel. Attachment of Pseudomonas fluorescens AH2 to stainless steel coated with water-soluble coatings of animal origin was significantly reduced as compared with noncoated stainless steel or stainless steel coated with laboratory substrate or extracts of plant origin. Coating with animal extracts also decreases adhesion of other food-relevant bacteria. The manipulation of adhesion was not attributable to growth inhibitory effects. Chemical analysis revealed that the stainless steels were covered by homogenous layers of adsorbed proteins. The presence of tropomyocin was indicated by appearance of proteins with similar molecular weight based in sodium dodecyl sulfate-polyacrylamide gel electrophoresis, in several extracts that reduced adhesion but also extracts not containing this protein reduced bacterial adhesion, indicating that several molecular species may be involved in the phenomenon. It is a common perception that food materials facilitate bacterial adhesion to surfaces however, this study demonstrates that aqueous coatings of food origin may actually reduce bacterial adhesion. Compounds from food extracts may potentially be used as nontoxic coatings to reduce bacterial attachment to inert surfaces.
Publisher: Elsevier BV
Date: 09-2016
DOI: 10.1016/J.MSEC.2016.04.031
Abstract: Poly(lactic-co-glycolic acid) (PLGA) and PLGA/gelatin random nanofibrous scaffolds embedded with different amounts of mesoporous silica nanoparticles (MSNPs) were fabricated using electrospinning method. To evaluate the effects of nanoparticles on the scaffolds, physical, chemical, and mechanical properties as well as in vitro degradation behavior of scaffolds were investigated. The mean diameters of nanofibers were 974±68nm for the pure PLGA scaffolds vs 832±70, 764±80, and 486±64 for the PLGA/gelatin, PLGA/10wt% MSNPs, and the PLGA/gelatin/10wt% MSNPs scaffolds, respectively. The results suggested that the incorporation of gelatin and MSNPs into PLGA-based scaffolds enhances the hydrophilicity of scaffolds due to an increase of hydrophilic functional groups on the surface of nanofibers. With porosity examination, it was concluded that the incorporation of MSNPs and gelatin decrease the porosity of scaffolds. Nanoparticles also improved the tensile mechanical properties of scaffolds. Using in vitro degradation analysis, it was shown that the addition of nanoparticles to the nanofibers matrix increases the weight loss percentage of PLGA-based s les, whereas it decreases the weight loss percentage in the PLGA/gelatin composites. Cultivation of rat pheochromocytoma cell line (PC12), as precursor cells of dopaminergic neural cells, on the scaffolds demonstrated that the introduction of MSNPs into PLGA and PLGA/gelatin matrix leads to improved cell attachment and proliferation and enhances cellular processes.
Publisher: American Chemical Society (ACS)
Date: 18-09-2009
DOI: 10.1021/BM900589R
Abstract: We utilize an aqueous extract of fish proteins (FPs) as a coating for minimizing the adsorption of fibrinogen (Fg) and human serum albumin (HSA). The surfaces include stainless steel (SS), gold (Au), silicon dioxide (SiO(2)), and poly(styrene) (PS). The adsorption processes (kinetics and adsorbed mass) are followed by quartz crystal microbalance with dissipation (QCM-D). Complementary surface information is provided by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). QCM-D shows no mass increases to any of the FP-coated surfaces upon treating with Fg or HSA. Also, when Fg- or HSA-coated surfaces are exposed to the FPs, a significant increase in adsorbed mass occurs because the FPs are highly surface-active displacing Fg. Additionally, fluorescence microscopy confirms that very little Fg adsorbs to the FP-coated surfaces. We propose that FP coatings prevent protein adsorption by steric stabilization and could be an alternative method for preventing unwanted bioadhesion on medical materials.
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5RA02471D
Abstract: The size of functional molecules influences the immobilization efficiency and properties of lipase immobilized on amine-functionalized magnetite–silica nanocomposite particles.
Publisher: Elsevier BV
Date: 03-2019
DOI: 10.1016/J.COLSURFB.2018.12.035
Abstract: Treatment of polymicrobial infections requires combination therapy with drugs that have different antimicrobial spectra and possibly work in synergy. However, the different pharmacokinetics and adverse side effects challenge the simultaneous delivery of multiple drugs at the appropriate concentrations to the site of infection. Formulation of multiple drugs in nano-carrier systems may improve therapeutic efficacy by increasing the local concentration and lowering the systemic concentration, leading to fewer side effects. In this study, we loaded polymyxin B and vancomycin on bare and carboxyl-modified mesoporous silica nanoparticles (B-MSNs and C-MSNs, respectively) to achieve simulataneous local delivery of antibiotics against Gram-positive and -negative bacteria. Polymyxin B adsorbed preferentially to nanoparticles compared to vancomycin. The total antibiotic loading was 563 μg and 453 μg per mg B-MSNs or C-MSNs, respectively. Both B-MSNs and C-MSNs loaded with antibiotics were effective against Gram-negative and Gram-positive bacteria. The antibiotics had synergistic interactions against Gram-negative bacteria, and the antimicrobial efficacy was higher for antibiotic-loaded C-MSNs compared to free antibiotics at the same concentration even though the cytotoxicity was lower. Our study shows that formulations of existing antibiotics in nanocarrier systems can improve their therapeutic efficiency, indicating that combination therapy with drug-loaded silica nanoparticles may provide a better treatment outcome for infections that require high concentrations of multiple drugs.
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5RA08405A
Abstract: Surface chemistry/charge and concentration of mesoporous silica nanoparticles have a great impact on the fibrillation process of α-Syn protein.
Publisher: American Chemical Society (ACS)
Date: 24-03-2016
Publisher: IOP Publishing
Date: 04-2011
DOI: 10.1088/0957-4484/22/22/225601
Abstract: We report a simple, rapid and cost-effective method based on evaporation induced assembly to grow 3D binary colloidal assemblies on a hydrophobic/hydrophilic substrate by simple drop casting. The evaporation of a mixed colloidal drop results in ring-like or uniform area deposition depending on the concentration of particles, and thus assembly occurs at the periphery of a ring or uniformly all over the drop area. Binary colloidal assemblies of different crystal structure are successfully prepared over a wide range of size ratios (γ = small/large) from 0.06 to 0.30 by tuning the γ of the micro- and nanoparticles used during assembly. The growth mechanism of 3D binary colloidal assemblies is investigated and it is found that electrostatic forces facilitate assembly formation until the end of the evaporation process, with capillary forces also playing a role. In addition, the effects of solvent type, humidity, and salt concentration on crystal formation and ordering behaviour are also examined. Furthermore, long range, highly ordered binary colloidal assemblies can be fabricated by the choice of a low conducting solvent combined with evaporation induced assembly.
Publisher: Wiley
Date: 04-02-2011
Publisher: Wiley
Date: 14-12-2016
Abstract: Given their highly porous nature and excellent water retention, hydrogel-based biomaterials can mimic critical properties of the native cellular environment. However, their potential to emulate the electromechanical milieu of native tissues or conform well with the curved topology of human organs needs to be further explored to address a broad range of physiological demands of the body. In this regard, the incorporation of nanomaterials within hydrogels has shown great promise, as a simple one-step approach, to generate multifunctional scaffolds with previously unattainable biological, mechanical, and electrical properties. Here, recent advances in the fabrication and application of nanocomposite hydrogels in tissue engineering applications are described, with specific attention toward skeletal and electroactive tissues, such as cardiac, nerve, bone, cartilage, and skeletal muscle. Additionally, some potential uses of nanoreinforced hydrogels within the emerging disciplines of cyborganics, bionics, and soft biorobotics are highlighted.
Publisher: Wiley
Date: 03-05-2011
Publisher: Elsevier BV
Date: 02-2013
DOI: 10.1016/J.COLSURFB.2012.08.044
Abstract: Materials coated with aqueous fish protein extracts can reduce bacterial adhesion, but the mechanism behind the observed effect is not fully understood. In this study we explore the physicochemical properties of fish muscle protein adlayers on four substrates: gold, stainless steel, polystyrene and silicon dioxide. The aims were (i) to determine if the anti-adhesive effect is independent of the underlying substrate chemistry, (ii) to link the physicochemical properties of the adlayer to its ability to repel bacteria, and (iii) to elucidate the mechanism behind this effect. The main proteins on all surfaces were the muscle proteins troponin, tropomyosin, and myosin, and the lipid binding protein apolipoprotein. The quantity, viscoelasticity, and hydration of the protein adlayers varied greatly on the different substrates, but this variation did not affect the bacterial repelling properties. Our results imply that these proteins adsorb to all substrates and provide a steric barrier towards bacterial adhesion, potentially providing a universal antifouling solution.
Publisher: Elsevier BV
Date: 10-2013
Publisher: Elsevier BV
Date: 06-2013
Publisher: Elsevier BV
Date: 02-2018
DOI: 10.1016/J.IJPHARM.2017.12.039
Abstract: Polymyxin B is a polycationic antibiotic used as the last line treatment against antibiotic-resistant Gram negative bacteria. However, application of polymyxin B is limited because of its toxicity effects. Herein, we used bare and surface modified mesoporous silica nanoparticles (MSNs) with an average diameter of 72.29 ± 8.17 nm as adsorbent for polymyxin B to improve its therapeutic properties. The polymyxin B adsorption onto MSN surfaces was explained as a function of pH, type of buffer and surface charge of nanoparticles, according to the ζ-potential of silica nanoparticles and adsorption kinetics results. The highest value of the adsorption capacity (about 401 ± 15.38 mg polymyxin B/ g silica nanoparticles) was obtained for the bare nanoparticles in Tris buffer, pH 9. Release profiles of polymyxin B showed a sustained release pattern, fitting Power law and Hill models. The antibiotic molecules-loaded nanoparticles showed enhanced antibacterial activity compared to free antibiotic against different Gram negative bacteria. Biocompatibility evaluation results revealed that loading of polymyxin B onto MSNs can decrease the cytotoxicity effects of the drug by reducing ROS generation. Our results suggest that formulation of drugs by adsorption onto MSNs may offer a way forward to overcome the adverse effects of some antibiotics such as polymyxin B without compromising their antimicrobial properties.
Publisher: Springer Science and Business Media LLC
Date: 21-09-2020
Publisher: Elsevier BV
Date: 10-2010
DOI: 10.1016/J.ULTRAMIC.2010.06.010
Abstract: Atomic force microscopy (AFM) holds great potential for studying the nanoscale surface structures of living cells, and to measure their interactions with abiotic surfaces, other cells, or specific biomolecules. However, the application of AFM in microbiology is challenging due to the difficulty of immobilising bacterial cells to a flat surface without changing the cell surface properties or cell viability. We have performed an extensive and thorough study of how to functionalise surfaces in order to immobilise living bacteria for AFM studies in liquid environments. Our aim was to develop a scheme which allows bacterial cells to be immobilised to a flat surface with sufficient strength to avoid detachment during the AFM scanning, and without affecting cell surface chemistry, structure, and viability. We compare and evaluate published methods, and present a new, reproducible, and generally applicable scheme for immobilising bacteria cells for an AFM imaging. Bacterial cells were immobilised to modified glass surfaces by physical confinement of cells in microwells, physisorption to positively charged surfaces, covalent binding to amine- or carboxyl-terminated surfaces, and adsorption to surfaces coated with highly adhesive polyphenolic proteins originating from the mussel Mytilus edulis. Living cells could be immobilised with all of these approaches, but many cells detached when immobilised by electrostatic interactions and imaged in buffers like PBS or MOPS. Cells were more firmly attached when immobilised by covalent binding, although some cells still detached during AFM imaging. The most successful method revealed was immobilisation by polyphenolic proteins, which facilitated firm immobilisation of the cells. Furthermore, the cell viability was not affected by this immobilisation scheme, and adhesive proteins thus provide a fast, reproducible, and generally applicable scheme for immobilising living bacteria for an AFM imaging.
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2JM30513E
Publisher: American Chemical Society (ACS)
Date: 06-05-2011
DOI: 10.1021/NN102867Z
Abstract: We demonstrate the use of binary colloidal assemblies as lithographic masks to generate tunable Au patterns on SiO(2) substrates with dimensions ranging from micrometers to nanometers. Such patterns can be modified with different chemistries to create patterns with well-defined sites for selective adsorption of proteins, where the pattern size and spacing is adjustable depending on particle choice. In our system, the binary colloidal assemblies contain large and small particles of similar or different material and are self-assembled from dilute dispersions with particle size ratios ranging from 0.10 to 0.50. This allows masks with variable morphology and thus production of chemical patterns of tunable geometry. Finally, the Au or SiO(2) regions of the pattern are surface modified with protein resistant oligoethyleneglycol self-assembled molecules, which facilitates site selective adsorption of proteins into the unmodified regions of the pattern. This we show with fluorescently labeled bovine serum albumin.
Location: United Kingdom of Great Britain and Northern Ireland
Location: Iran (Islamic Republic of)
No related grants have been discovered for Ayyoob Arpanaei.