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    Production of Reduced Graphene Oxide by Using Three Different Microorganisms and Investigation of Their Cell Interactions
    (Amer Chemical Soc, 2023) Utkan, Guldem; Yumusak, Gorkem; Tunali, Beste Cagdas; Ozturk, Tarik; Turk, Mustafa
    Despite the hugeand efficient functionalities of reduced grapheneoxide (RGO) for bioengineering applications, the use of harsh chemicalsand unfavorable techniques in their production remains a major challenge.Microbial production of reduced graphene oxide (RGO) using specificbacterial strains has gained interest as a sustainable and efficientmethod. The reduction of GO to RGO by selected bacterial strains wasachieved through their enzymatic activities and resulted in the removalof oxygen functional groups from GO, leading to the formation of RGOwith enhanced structural integrity. The use of microorganisms offersa sustainable approach, utilizing renewable carbon sources and mildreaction conditions. This study investigates the production of RGOusing three different bacterial strains: Lactococcuslactis (L. Lactis), Lactobacillus plantarum (L. plantarum), and Escherichia coli (E. coli) and evaluates its toxicity for safe utilization.The aim is to assess the quality of the produced RGO and evaluateits toxicity for potential applications. Thus, this study focusedon the microbial production of reduced graphene oxides well as theinvestigation of their cellular interactions. Graphite-derived grapheneoxide was used as a starting material and microbially reduced GO productswere characterized using the FTIR, Raman, XRD, TGA, and XPS methodsto determine their physical and chemical properties. FTIR shows thatthe epoxy and some of the alkoxy and carboxyl functional groups werereduced by E. coli and L. lactis, whereas the alkoxy groups were mostlyreduced by L. plantarum. The I (D)/I (G) ratio fromRaman spectra was found as 2.41 for GO. A substantial decrease inthe ratio as well as defects was observed as 1.26, 1.35, and 1.46for ERGO, LLRGO, and LPRGO after microbial reduction. The XRD analysisalso showed a significant reduction in the interlayer spacing of theGO from 0.89 to 0.34 nm for all the reduced graphene oxides. TGA resultsshowed that reduction of GO with L. lactis provided more reduction than other bacteria and formed a structurecloser to graphene. Similarly, analysis with XPS showed that L lactisprovides the most effective reduction with a C/O ratio of 3.70. Inthe XPS results obtained with all bacteria, it was observed that theC/O ratio increased because of the microbial reduction. Toxicity evaluationswere performed to assess the biocompatibility and safety of the producedRGO. Cell viability assays were conducted using DLD-1 and CHO celllines to determine the potential cytotoxic effects of RGO producedby each bacterial strain. Additionally, apoptotic, and necrotic responseswere examined to understand the cellular mechanisms affected by RGOexposure. The results indicated that all the RGOs have concentration-dependentcytotoxicity. A significant amount of cell viability of DLD-1 cellswas observed for L. lactis reducedgraphene oxide. However, the highest cell viability of CHO cells wasobserved for L. plantarum reduced grapheneoxide. All reduced graphene oxides have low apoptotic and necroticresponses in both cell lines. These findings highlight the importanceof considering the specific bacterial strain used in RGO productionas it can influence the toxicity and cellular response of the resultingRGO. The toxicity and cellular response to the final RGO can be affectedby the particular bacterial strain that is employed to produce it. This information will help to ensure that RGO is used safely in avariety of applications, including tissue engineering, drug deliverysystems, and biosensors, where comprehension of its toxicity profileis essential.
  • [ X ]
    Öğe
    The comparison of contribution of GO and rGO produced by green synthesis to the properties of CMC-based wound dressing material
    (Elsevier, 2024) Karaca, Ozge Guluzar; Moran, Busra; Turk, Mustafa; Bal-Ozturk, Ayca; Izbudak, Burcin; Aydin, Yasar Andelib; Utkan, Guldem
    Herein, GO (graphene oxide) or rGO (reduced graphene oxide) which is produced by the green synthesis method using plant extract (Laurus nobilis) was incorporated into a polymeric structure consisting of carboxymethyl cellulose (CMC) and polyethylene glycol (PEG) to produce a wound dressing material with enhanced mechanical and electrical properties. The effect of GO and rGO on the wound dressing features of the produced materials was investigated and compared to each other. Conductivity tests demonstrated that rGO contributed more significantly to the electrical conductivity than GO. While rGO-CMC/PEG/CA reached 3.01 x 10-6 S.cm- 1 as the conductivity value, that of GO-CMC/PEG/CA was determined as 0.85 x 10-6 S.cm- 1. As for the mechanical tests, it was seen that rGO achieved the best results in terms of elastic modulus (588.62 N/mm2), tensile strength (94.95 MPa) and elongation at break (17.64 %) compared to GO reinforced and pure hydrogel. Curcumin and ascorbic acid were used for antibiotic-free wound treatment and their release kinetics were also modeled. The results showed that rGO reinforced hydrogel provided a more controlled release. All results assured that both the produced GO reinforced and especially rGO reinforced hydrogels could be utilized as modern wound dressing materials with suitable properties to achieve remarkable results for wound healing.