Publications by authors named "Kyriaki Marina Lyra"

Article Synopsis
  • The growth of the graphite market is driven by the demand for lithium-ion batteries, leading to substantial waste in the form of graphite fines.
  • Researchers have developed a method to transform these waste fines into graphene oxide-based nanohybrids, which are effective and non-toxic antibacterial agents.
  • The new nanohybrids, specifically GO-GPEI and GO-SPEI, show superior antibacterial properties against E. coli and low toxicity to mammalian cells, making them promising candidates for use in disinfection applications.
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Hyperbranched polyethyleneimine having 25,000 Da molecular weight was functionalized by a simple sulfopropylation reaction, affording a novel N-sulfopropylated PEI derivative (PEI-SO ). The successful introduction of N-sulfopropyl and sulfobetaine groups to the amino groups of PEI was spectroscopically confirmed. Furthermore, the antibacterial and anti-cyanobacterial activity of PEI-SO in comparison to the parent PEI were investigated on two type heterotrophic bacteria, i.

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Non-toxic carbon-based hybrid nanomaterials based on carbon nanodisks were synthesized and assessed as novel antibacterial agents. Specifically, acid-treated carbon nanodisks (oxCNDs), as a safe alternative material to graphene oxide, interacted through covalent and non-covalent bonding with guanidinylated hyperbranched polyethyleneimine derivatives (GPEI5K and GPEI25K), affording the oxCNDs@GPEI5K and oxCNDs@GPEI25K hybrids. Their physico-chemical characterization confirmed the successful and homogenous attachment of GPEIs on the surface of oxCNDs, which, due to the presence of guanidinium groups, offered them improved aqueous stability.

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An efficient doxorubicin (DOX) drug delivery system with specificity against tumor cells was developed, based on multi-walled carbon nanotubes (MWCNTs) functionalized with guanidinylated dendritic molecular transporters. Acid-treated MWCNTs (oxCNTs) interacted both electrostatically and through hydrogen bonding and van der Waals attraction forces with guanidinylated derivatives of 5000 and 25,000 Da molecular weight hyperbranched polyethyleneimine (GPEI5K and GPEI25K). Chemical characterization of these GPEI-functionalized oxCNTs revealed successful decoration with GPEIs all over the oxCNTs sidewalls, which, due to the presence of guanidinium groups, gave them aqueous compatibility and, thus, exceptional colloidal stability.

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Article Synopsis
  • Oxidized multi-walled carbon nanotubes (oxCNTs) were modified with quaternized hyperbranched poly(ethyleneimine) derivatives (QPEIs), leading to stable dispersions in water that remained effective for over 12 months.
  • The modified oxCNTs demonstrated a strong antibacterial and anti-cyanobacterial effect against specific bacteria, with activity increasing with higher quaternization degrees.
  • Cytotoxicity tests showed that these hybrids were compatible with human and mouse cells, making them promising candidates for applications in disinfection and managing harmful cyanobacterial blooms.
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In the present study, we developed novel -glucosidase-based nano-biocatalysts for the bioconversion of oleuropein to hydroxytyrosol. Using non-covalent or covalent immobilization approaches, -glucosidases from almonds and were attached for the first time on oxidized and non-oxidized porous carbon cuboids (PCC). Various methods were used for the characterization of the bio-nanoconjugates, such as Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and fluorescence spectroscopy.

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