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    GOpublications: Nano Silver-Graphene Oxide In The Fight Against Root Canal Infections

    GOpublications: Nano Silver-Graphene Oxide In The Fight Against Root Canal Infections

    Root canal treatment is a dental procedure used to rid tooth centres of bacterial infections. This involves both the mechanical debridement and chemical irrigation of infected teeth. While the current success rate stands at up to a remarkable 90%, the one prevailing cause of treatment failure stems from the lack of ability to access confined areas between adjacent teeth, thereby allowing bacterial infections to persist, impenetrable biofilms to form and thus antimicrobial resistance to develop. So far, the most effective and penetrable irrigant used to date is sodium hypochlorite (NaOCl), however, due to its caustic and deleterious nature towards dentine collagen, the need to find alternatives have become increasingly important.  

    In response to this, researchers at King’s College London have turned their attention to William Blythe’s own graphene oxide (GO), not only for its 2D monolayer sheet structure, but also for its multiple oxygenic functional groups: the hydroxyl, carboxyl and epoxide, which allows for a high binding capability. Researchers here have exploited the above features and properties to synthesise a Ag-GO matrix for use as a novel irrigant by reducing AgNO3 to Ag nanoparticles using 0.01 M NaBH4 in the presence of GO. The resulting 0.25% Ag-GO irrigant was then tested on a biofilm covered ex vivo tooth model and its antimicrobial activity compared with the following existing irrigants: sterile saline, 1% and 2.5% NaOCl, 2% chlorhexidine gluconate (CHX) and 17% EDTA. Each irrigant was also tested with three different activation methods including conventional irrigation, ultrasonically activated irrigation and XP Endo Finisher. The antimicrobial efficacy of each group was then assessed using a combination of paper point sampling, microbial counting and by measuring dentine tubule biofilm disruption levels. 

    Results from this study showed that although 2.5% NaOCl, today’s gold standard irrigant, caused maximum biofilm disruption, ultrasonically activated Ag-GO, caused the largest reduction in total biovolumes overall. This overwhelming success was largely attributed to GO’s multipotent mechanism of antimicrobial action. Specifically, GO’s layered bidimensional sheets, which allowed for the enveloping and isolating of microorganisms, while the sharp-edged feature of said sheets act as cell membrane cutters, causing rapid intracellular cytoplasm leakage, inactivated proliferation and thus cell death. This application not only highlights GO’s usefulness in future dental treatments but more impressively brings to light the potential for the impregnation of various different chemicals within GO in order to form a composite matrix with tuneable properties.  

    For more information on our collection of GO products and applications, please contact our Technical Director, Mike Butler or visit our website

    Dental materials, 2019, 35, 11, pp. 1614 - 1629 

    GOpublications: Anticancer Properties of Graphene Oxide Demonstrated in Bone Cancer Treatment

    GOpublications: Anticancer Properties of Graphene Oxide Demonstrated in Bone Cancer Treatment

    Osteosarcoma (OS) is a common type of bone cancer, typically found in the long bones of the arms and legs. This disease is most prevalent among children and elderly populations, and is characterised by a shockingly low survival rate of 20 %, post metastasis. Two genes, insulin growth factor 1 (IGF1) and the insulin growth factor binding protein 3 (IGFBP3), have been named the main culprits responsible for the tumorigenesis of OS. Normally, these genes work in tandem to regulate cell proliferation by controlling apoptosis, the cell death mechanism. However, in the case of OS patients, these mechanisms fail, resulting in tumour formation.

    Current treatment plans for OS involve surgery followed by chemotherapy. However, existing chemotherapy drugs such as cisplatin and doxorubicin, consistently fail to specifically target cancer cells, resulting in systemic toxicity which in turn leads to the development of undesired side effects such as hair loss and skin problems. Thus, a markedly low survival rate coupled with the limitations of presently available chemotherapy drugs has created an urgent need for a more specific, but less toxic chemotherapy drug formulation.

    Researchers at the University of Atlanta have looked to graphene oxide (GO), previously proven to exhibit low toxicity but also a high relative selectivity for cancer cells. In this study, researchers compared the toxicity of William Blythe GO on human OS cell lines, both with and without the implicated IGF1 and IGFBP3 genes, with the healthy osteoblast cell line hFOB1.19. All cell lines were treated to 0, 20 and 50 micrograms of GO, and left to incubate for 30 minutes, 2 hours, 4 hours, 24 hours and 48 hours. Morphological changes were then observed under an inverted microscope.

    Micrographs of OS cell lines showed evidence of cell disorientation, cell disordering and cell debris, all resulting from GO induced apoptosis (cell death). Generally, GO induced apoptosis was highest in OS cell lines with knocked out IGF1 and IGFBP3 genes and when subjected to longer incubation times of 24 and 48 hours and when exposed to higher GO concentrations. Overall, observed morphological changes were more significant in OS cell lines compared to the normal osteoblast cell line hFOB1.19, proving GO to be selectively more toxic to OS cells. The cytotoxic effects of GO the cancerous cells demonstrated in this study could lead to future development towards the use of GO in the treatment of OS, with the next step being ­in vivo studies.  

    If you would like to know more about this application or are in need of advice on how our GO can help you, please get in touch with our Business Development Manager, Mike Butler, or visit our website.

    Journal of cancer, 2020, 11, 17, pp. 5007 - 5023

    Graphene Oxide Enhanced Organic Solvent Nanofiltration

    Graphene Oxide Enhanced Organic Solvent Nanofiltration

    Organic solvent nanofiltration (OSN) is an important technique used by the pharmaceutical and petrochemical industries to selectively separate molecules in processes such as solvent exchange, catalyst recovery and purification.

    These processes are highly resource intensive because of the high pressures and large amounts of solvent required, so researchers endeavour to find new materials that can increase permeance through the filter membrane whilst retaining high selectivity.  2D materials such as graphene and graphene oxide are attractive high performance additive solutions to this problem.

    In 2018, researchers at the University of Manchester investigated the functionalisation of poly(benzimidazole) OSN membranes with graphene oxide supplied by William Blythe. Graphene oxide excels in this application through its versatility during the deposition process in being both water and solvent soluble and chemically reactive via the oxygenated functional groups on the surface of the sheets.  These features make it easy to handle and provide tuneable functionality.

    Blanford and colleagues identified that the hydroxyl groups on graphene oxide can be covalently cross-linked to the polymeric membrane, and this functionality improves the separation performance.

    The functionalisation process consisted of three steps: i) hydroxylating the poly(benzimidazole) via N-benzylation; ii) cross linking the hydroxylated poly(benzimidazole) with toluene diisocyanate; and iii) anchoring the graphene oxide sheets via covalently bonding to toluene diisocyanate and cross-linking with other graphene oxide sheets.

    The performance of the membranes was evaluated in cross-flow filtration.  The researchers found that the membrane containing graphene oxide achieved an acetone permeance that was 18 times greater than a commercial OSN membrane and 5 times greater than the control poly(benzimidazole) membrane.  Other solvents were also trialled which exhibited similarly high permeance results, despite the concentration of graphene oxide in the membrane being very low (1-2%).

    This is an exemplary study for how high-quality graphene oxide from William Blythe Ltd can be used at commercially viable scales to achieve significant performance enhancements.  To learn more about graphene oxide functionalisation for optimisation in your application, please get in touch with our business development manager Mike Butler and visit our website.

    ACS Appl. Mater. Interfaces, 2018, 10, 18, pp.16140-16147.

    Early Cancer Detection using Graphene Oxide

    Breast cancer is one of the most common cancers within the UK and it’s the most common cancer in women universally. According to Cancer Research UK, in 2015 23% of breast cancer cases reported were deemed preventable.  Researchers found that the gene BRCA1, a breast cancer susceptibility gene, is responsible for 80% of breast and ovarian cancer families. There has also been some correlation between having this gene and your susceptibility to pancreatic and colon cancers. Finding this link has been vital in aiding disease prevention. The biotechnology industry is working towards producing efficient devices to be able to detect this gene in order to prevent and reduce the mortality risk.

    The use of graphene oxide in biosensors has been growing exponentially due to the highly useful specifications of GO.  Shahrokhian and Salimian successfully produced a graphene oxide coated carbon electrode for DNA probe immobilisation, which was found to be more efficient than current electrodes used for this purpose. The GO layer on the electrode allows for bonding, via an amide bond, to the DNA which makes it an ultrasensitive detector. 

    To ensure this method of DNA analysis is fast and simple, Shahrokhian and Salimian applied electrochemical reduction methods, which in turn produced rGO on the electrode surface.  As the graphene oxide has a larger accessible surface area, it accelerates the electron transfer process, enhancing the conductivity of the electrode.

    By adding graphene oxide to the coating on the electrode, researchers were able to produce a highly sensitive biosensor. The properties of GO make it ideal for this area of research and the flexibility of being able to tune the GO properties specific to the research purpose, make it highly applicable in biotechnology. 

    The range of graphene based materials in current research by academic groups around the world highlights the effect that they will one day have on day to day applications. If you have any enquiries about the applications of graphene oxide or how it can improve your existing applications, please get in touch and one of the GOgraphene team will be happy to help.

    Sensors and Actuators, B, 2018, 266, 160-169

    Graphene Oxide in Food Packaging

    Graphene Oxide in Food Packaging

    Packaging in the food industry is changing. As consumers become more aware of the detriments of single use plastics, there is pressure within the supply chain to eliminate these, whilst maintaining a high standard of quality.  It is essential that new packaging technologies do not compromise on protection; the current standards of freshness must be maintained by ensuring that packaging is waterproof and doesn’t break or promote deterioration of food. This is especially important during transport, which is often on a global scale and will inevitably result in some strain on the packaging. Many research departments are striving to not just match the level of protection provided by conventional packaging today, but to improve properties such as anti-microbial activity, UV blocking and breathability, in order to ensure that the new packaging is a desirable and cost effective alternative.

    Gelatin based biopolymers are being considered as a possible alternative to plastic, as gelatin is widely accessible, inexpensive and easy to process. However, the biopolymer is also susceptible to bacterial attack, breaks easily and is highly sensitive to moisture which decreases its suitability as a packaging material. The incorporation of graphene oxide into the polymer matrix has been shown to improve all these properties, as well as promoting thermal and light stability. GO is particularly suited to this use as, like gelatin, it is biodegradable (albeit with emzymes) and hence, environmentally benign. Gelatin alone would degrade too easily, but GO addition strengthens the material sufficiently that it is much more likely to withstand transport and handling. Furthermore, since GO interacts and bonds strongly, other additives can easily be included in the polymer composite to further enhance the material.

    A recent study shows that combining a gelatin polymer with GO nanosheets and mussel-inspired polydopamine (PDA) resulted in a vastly tougher material with significant advantages. Mussels have been found to be remarkably good at sticking to a wide variety of surfaces, including plenty that are adhesion resistant. This led to in-depth studies of the proteins they secrete and resulted in PDA use becoming increasingly common. Here, GO was considered an effective means of transporting PDA, and PGO was synthesised (PDA-GO).

    GO acted as an excellent cross-linking agent and enabled the integration of silver and cellulose into the structure, which previously required toxic chemicals and complex processes. These additives further enhanced anti-microbial and strengthening properties respectively. The large number of components essentially filled gaps within the biopolymer matrix, hence it’s improved impermeability against UV light and water. This is somewhat surprising, as GO is often hailed as a permeable material and is being widely applied to water filtration systems. However, in this instance, the hydrogen bonding from the GO reduced the availability of hydrophilic groups in the composite and therefore decreased water uptake.

    Compared to other processes towards forming gelatin biopolymers, GO nanosheets enabled a much simpler and more environmentally friendly route, which resulted in a biodegradable polymer that was effective against common bacteria including E. coli and S. aureus.

    This application is just one of many that utilise the unique properties of graphene and graphene oxide and further demonstrates the wide range of potential applications. If you have any enquiries about the applications of graphene oxide or how it can improve your existing applications, please get in touch and one of the GOgraphene team will be happy to help.

    Industrial Crops and Products, 2019, 132, pp.197-212.