Browsing by Author "Assad, Mhd"

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    Nanotheranostics: A possible solution for drug-resistant staphylococcus aureus and their biofilms?
    (Multidisciplinary Digital Publishing Institute (MDPI), 2021-01) Mosselhy, Dina A.; Assad, Mhd; Sironen, Tarja; Elbahri, Mady; Department of Chemistry and Materials Science; Nanochemistry and Nanoengineering; University of Helsinki
    Staphylococcus aureus is a notorious pathogen that colonizes implants (orthopedic and breast implants) and wounds with a vicious resistance to antibiotic therapy. Methicillin-resistant S. aureus (MRSA) is a catastrophe mainly restricted to hospitals and emerged to community reservoirs, acquiring resistance and forming biofilms. Treating biofilms is problematic except via implant removal or wound debridement. Nanoparticles (NPs) and nanofibers could combat superbugs and biofilms and rapidly diagnose MRSA. Nanotheranostics combine diagnostics and therapeutics into a single agent. This comprehensive review is interpretative, utilizing mainly recent literature (since 2016) besides the older remarkable studies sourced via Google Scholar and. We unravel the molecular S. aureus resistance and complex biofilm. The diagnostic properties and detailed antibacterial and antibiofilm NP mechanisms are elucidated in exciting stories. We highlight the challenges of bacterial infections nanotheranostics. Finally, we discuss the literature and provide “three action appraisals”. (i) The first appraisal consists of preventive actions (two wings), avoiding unnecessary hospital visits, hand hygiene, and legislations against over-the-counter antibiotics as the general preventive wing. Our second recommended preventive wing includes preventing the adverse side effects of the NPs from resistance and toxicity by establishing standard testing procedures. These standard procedures should provide breakpoints of bacteria’s susceptibility to NPs and a thorough toxicological examination of every single batch of synthesized NPs. (ii) The second appraisal includes theranostic actions, using nanotheranostics to diagnose and treat MRSA, such as what we call “multifunctional theranostic nanofibers. (iii) The third action appraisal consists of collaborative actions.
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    Vacuum evaporative deposition of photochromic spirophenanthroxazine thin films and their solvato-bleaching feature
    (2019-08-20) Assad, Mhd; Soliman, Ahmed; Yetik, Mehmet; Kemian tekniikan korkeakoulu; Elbahri, Mady
    Stimuli-responsive materials are the major contributors to functional materials that play a significant role in many fields such as sensors and actuators. Among these materials photochromic molecules has attracted both the scientific and industrial communities, due to their unique features. When exposed to UV radiation photochromic materials would either exhibit isomerization (e.g. trans-cis / cis-trans), or result in a ring opening /closure, which would result not only in a change in their absorption spectrum, but also in their chemical and physical properties such as refractive indices, dielectric constants, oxidation-reduction potentials and geometrical structures. The embedment of photochromic molecules particularly Spirooxazine within a polymer matrix has been studied significantly in literature, yet due to its synthesis limitations standalone systems including the transform from particle, percolated and continuous film where never reported to the best of our knowledge. Thus, herein we introduced the deposition of standalone Spirooxazine thin films via evaporative deposition with emphasizing the percolated and continuous film samples. The cluster deposition of SPO is being extensively studied elsewhere by our group under the framework of ASCI project. The deposited films were studied for their chemical integrity, thickness, crystallinity, density, and photochromic ability. In addition, the deposited films decay kinetics were studied under both constant temperature and the influence of multiple volatile organic compounds (VOCs) such as Acetone, Acetonitrile and Isopropanol. Where a new unreported term, Solvato-bleaching, was assigned to describe the color fading kinetics upon VOCs exposure. It was determined that the solvato-bleaching rate of the deposited film is dependent on the polarity of the solvent, so that with decreasing polarity the rate increases. However, some exceptions may take place when the surface morphology changes, thus we assume that the interaction is a surface limited reaction.