Publications by authors named "Muhammad Asim Akhtar"

3 Publications

  • Page 1 of 1

Fabrication and Characterization of Ag-Sr-Substituted Hydroxyapatite/Chitosan Coatings Deposited via Electrophoretic Deposition: A Design of Experiment Study.

ACS Omega 2020 Sep 28;5(36):22984-22992. Epub 2020 Aug 28.

Department of Materials Science and Engineering, Institute of Space Technology Islamabad, 1, Islamabad Highway, Islamabad 44000, Pakistan.

In this study, silver-strontium-doped hydroxyapatite (AgSr-HA)/chitosan composite coatings were deposited on a 316L stainless steel (SS) substrate via electrophoretic deposition (EPD). The Taguchi design of experiment (DoE) approach was used to optimize the EPD parameters such as the applied voltage, interelectrode spacing, and deposition time. Furthermore, the concentration of AgSr-HA particles in the suspension was also optimized via the DoE approach. DoE results demonstrated that the "homogeneous" coatings were obtained at the deposition time of 7 min, deposition voltage of 20 V, and at a concentration of 5 g/L AgSr-HA particles in the suspension. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), antibacterial studies, contact angle, and roughness measurements were performed to characterize the optimized coatings. SEM images confirmed the deposition of chitosan/AgSr-HA on the SS substrate. The wettability studies indicated the hydrophilic nature of the chitosan/AgSr-HA composite coatings, which confirmed that the developed coatings are suitable for biomedical applications, e.g., orthopedics. The average surface roughness of the chitosan/AgSr-HA composite coatings was in a suitable range used to attach the bone marrow stromal cells. Chitosan/AgSr-HA composite coatings showed an effective antibacterial effect against Gram-positive and Gram-negative bacteria. Moreover, the coatings developed apatite crystals on their surface upon immersion in simulated body fluid.
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http://dx.doi.org/10.1021/acsomega.0c02582DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7495738PMC
September 2020

Electrophoretic Deposition of Copper(II)-Chitosan Complexes for Antibacterial Coatings.

Int J Mol Sci 2020 Apr 10;21(7). Epub 2020 Apr 10.

Department of Materials Science and Engineering, Institute of Biomaterials, University of Erlangen-Nuremberg, Cauerstr.6, 91058 Erlangen, Germany.

Bacterial infection associated with medical implants is a major threat to healthcare. This work reports the fabrication of Copper(II)-Chitosan (Cu(II)-CS) complex coatings deposited by electrophoretic deposition (EPD) as potential antibacterial candidate to combat microorganisms to reduce implant related infections. The successful deposition of Cu(II)-CS complex coatings on stainless steel was confirmed by physicochemical characterizations. Morphological and elemental analyses by scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) spectroscopy verified the uniform distribution of copper in the Chitosan (CS) matrix. Moreover, homogeneous coatings without precipitation of metallic copper were confirmed by X-ray diffraction (XRD) spectroscopy and SEM micrographs. Controlled swelling behavior depicted the chelation of copper with polysaccharide chains that is key to the stability of Cu(II)-CS coatings. All investigated systems exhibited stable degradation rate in phosphate buffered saline (PBS)-lysozyme solution within seven days of incubation. The coatings presented higher mechanical properties with the increase in Cu(II) concentration. The crack-free coatings showed mildly hydrophobic behavior. Antibacterial assays were performed using both Gram-positive and Gram-negative bacteria. Outstanding antibacterial properties of the coatings were confirmed. After 24 h of incubation, cell studies of coatings confirms that up to a certain threshold concentration of Cu(II) were not cytotoxic to human osteoblast-like cells. Overall, our results show that uniform and homogeneous Cu(II)-CS coatings with good antibacterial and enhanced mechanical stability could be successfully deposited by EPD. Such antibiotic-free antibacterial coatings are potential candidates for biomedical implants.
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http://dx.doi.org/10.3390/ijms21072637DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7177350PMC
April 2020

A nanocomposite prepared from magnetite nanoparticles, polyaniline and carboxy-modified graphene oxide for non-enzymatic sensing of glucose.

Mikrochim Acta 2019 04 2;186(5):267. Epub 2019 Apr 2.

Interdisciplinary Research Centre in Biomedical Materials (IRCBM), COMSATS University Islamabad Lahore Campus, Lahore, 55150, Pakistan.

The authors report on the synthesis of carboxy functionalized graphene oxide (fGO) decorated with magnetite (FeO) nanoparticles. The resulting nanomaterial was used to prepare a composite with polyaniline (PANI) which was characterized by UV-vis, Fourier transform-infrared and Raman spectroscopies. Its surface morphologies were characterized by atomic force and scanning electron microscopies. A screen-printed carbon electrode was then modified with the nanocomposite to obtain an enzyme-free glucose sensor. The large surface of fGO and FeO along with the enhanced charge transfer capability of PANI warrant a pronounced electrochemical response (typically measured at 0.18 V versus Ag/AgCl) which is suppressed in the presence of glucose. This reduction of current by glucose was used to design a sensitive method for quantification of glucose. The response of the modified SPCE is linear in the 0.05 μM - 5 mM glucose concentration range, and the lower detection limit is 0.01 μM. Graphical abstract Schematic illustration of in-situ anchoring of Iron oxide on functionalized graphene oxide and synthesis of its polymeric nanocomposite for non-enzymatic detection of Glucose. The nanocomposite modified screen printed interface enabled monitoring of glucose at lower potential with higher precision. GO (graphene oxide), fGO (functionalized graphene oxide), PANI (polyaniline).
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http://dx.doi.org/10.1007/s00604-019-3364-2DOI Listing
April 2019