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Graphene quantum dots for multiple biomedical applications
Materials Today Volume 19, Number 1 January/February 2016
NEWS
News Graphene quantum dots for multiple biomedical applications A consortium of British and Chinese scientists has produced novel quantum dots that could be used in imaging, drug delivery and photothermal therapy [R. Justin, et al. Carbon 97 (2016) 54–70]. Nanotechnology has had a rapidly-growing role to play in biomedical technology in the last five years. Graphene and its derivatives are being investigated for everything from biosensing to cancer therapy. Nanoparticles have been tested for use in magnetic imaging and targeted drug delivery, and quantum dots are being studied for use in fluorescent imaging. But a collaboration between researchers in Shanghai and Sheffield may just have found a material that combines all of these properties – magnetic graphene oxide-iron oxide quantum dots (MGQDs). To be reported in an upcoming issue of Carbon [doi:10.1016/j.carbon.2015.06.070], these
dots have the potential to be used in magnetic resonance imaging (MRI), fluorescent imaging, targeted drug delivery and photothermal therapy. The graphene oxide-iron oxide quantum dots in question were synthesizes by dispersing graphene oxide (GO) in a solution of iron oxide precursors (IO), to make nanoparticles. These were then autoclaved to produce the final MGQDs. A common drug for skin treatment (lidocaine hydrochloride) was then loaded onto the dots, with a ratio of drug to QD of 0.31:1. Two types of cells were used to test the drug-loaded MGQDs–dermal fibroblasts (from human skin) for imaging and drug delivery, and HeLa cells for photothermal experiments. External magnetic fields from an MRI were used to precisely manipulate the MGQDs, but without causing any residual magnetization to the cell. Once delivered to
the skin cells, the drug was found to be steadily released from the quantum dots over 8 h. For fluorescent imaging, both toxicity and luminescence were measures. The MGQDs displayed very low toxicity, while still emitting the same level of luminescence as cadmium telluride quantum dots (which are toxic to cells). And for the photothermal measurements, a near-infrared laser was used to irradiate a suspension of HeLa cells and MGQDs. This increased the temperature of the cell by 508C, which suggests that MGQDs could be potentially used for the ablation of tumors. This work is ongoing, and several questions remain around the use of MGQDs, but it is hoped that this work opens a door to a novel nanosystem suitable for use in the detection, monitoring and treatment of diseases. Laurie Winkless
Cleaner air-con thanks to antifungal aluminium Korean engineers have shown that a specially-designed aluminium surface could help improve the air quality produced by air-conditioning units [Y. Kim and W. Hwang, Mater. Lett. 161 (2015) 234–239]. We’ve all become accustomed to using heating, ventilation and air-conditioning systems to manage the environment in our homes and offices. If improperly maintained, these systems can offer the perfect conditions for growth and circulation of some microbial contaminants that can aggravate respiratory conditions like asthma or bronchitis. The issue is that aluminium – which most commercial evaporators are made from –
isn’t inherently antimicrobial, so requires careful and frequent cleaning to minimise contamination. Other metals such as copper, silver, or titanium are anti-microbial but are also significantly higher in cost than aluminium, rendering them impractical for widespread use. But a recent paper in Materials Letters [doi:10.1016/j.matlet.2015.08. 103] reports on a coated aluminium surface that obstructs the adhesion and spreading of microbes. The idea is based on superhydrophobicity – whereby a rough surface provides a low-energy surface that water cannot stick to. Given the importance of water to the
development of biological life forms, removing it from the surface should also stop the microbes from growing. And so the researchers designed a series of surfaces with varying wettability, using contact angle (CA) measurements to determine their wetting characteristics. Untreated aluminium is already weakly hydrophobic (water can partly stick to the surface, with a contact angle of 808). By coating it with a polymer, the contact angle was increased to 1108, making it hydrophobic. The superhydrophobic surface (CA = 1708) was produced by treating the aluminium in oxalic acid and then coating the rough 1369-7021/http://dx.doi.org/10.1016/j.mattod.2015.11.023
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NEWS
News Graphene quantum dots for multiple biomedical applications A consortium of British and Chinese scientists has produced novel quantum dots that could be used in imaging, drug delivery and photothermal therapy [R. Justin, et al. Carbon 97 (2016) 54–70]. Nanotechnology has had a rapidly-growing role to play in biomedical technology in the last five years. Graphene and its derivatives are being investigated for everything from biosensing to cancer therapy. Nanoparticles have been tested for use in magnetic imaging and targeted drug delivery, and quantum dots are being studied for use in fluorescent imaging. But a collaboration between researchers in Shanghai and Sheffield may just have found a material that combines all of these properties – magnetic graphene oxide-iron oxide quantum dots (MGQDs). To be reported in an upcoming issue of Carbon [doi:10.1016/j.carbon.2015.06.070], these
dots have the potential to be used in magnetic resonance imaging (MRI), fluorescent imaging, targeted drug delivery and photothermal therapy. The graphene oxide-iron oxide quantum dots in question were synthesizes by dispersing graphene oxide (GO) in a solution of iron oxide precursors (IO), to make nanoparticles. These were then autoclaved to produce the final MGQDs. A common drug for skin treatment (lidocaine hydrochloride) was then loaded onto the dots, with a ratio of drug to QD of 0.31:1. Two types of cells were used to test the drug-loaded MGQDs–dermal fibroblasts (from human skin) for imaging and drug delivery, and HeLa cells for photothermal experiments. External magnetic fields from an MRI were used to precisely manipulate the MGQDs, but without causing any residual magnetization to the cell. Once delivered to
the skin cells, the drug was found to be steadily released from the quantum dots over 8 h. For fluorescent imaging, both toxicity and luminescence were measures. The MGQDs displayed very low toxicity, while still emitting the same level of luminescence as cadmium telluride quantum dots (which are toxic to cells). And for the photothermal measurements, a near-infrared laser was used to irradiate a suspension of HeLa cells and MGQDs. This increased the temperature of the cell by 508C, which suggests that MGQDs could be potentially used for the ablation of tumors. This work is ongoing, and several questions remain around the use of MGQDs, but it is hoped that this work opens a door to a novel nanosystem suitable for use in the detection, monitoring and treatment of diseases. Laurie Winkless
Cleaner air-con thanks to antifungal aluminium Korean engineers have shown that a specially-designed aluminium surface could help improve the air quality produced by air-conditioning units [Y. Kim and W. Hwang, Mater. Lett. 161 (2015) 234–239]. We’ve all become accustomed to using heating, ventilation and air-conditioning systems to manage the environment in our homes and offices. If improperly maintained, these systems can offer the perfect conditions for growth and circulation of some microbial contaminants that can aggravate respiratory conditions like asthma or bronchitis. The issue is that aluminium – which most commercial evaporators are made from –
isn’t inherently antimicrobial, so requires careful and frequent cleaning to minimise contamination. Other metals such as copper, silver, or titanium are anti-microbial but are also significantly higher in cost than aluminium, rendering them impractical for widespread use. But a recent paper in Materials Letters [doi:10.1016/j.matlet.2015.08. 103] reports on a coated aluminium surface that obstructs the adhesion and spreading of microbes. The idea is based on superhydrophobicity – whereby a rough surface provides a low-energy surface that water cannot stick to. Given the importance of water to the
development of biological life forms, removing it from the surface should also stop the microbes from growing. And so the researchers designed a series of surfaces with varying wettability, using contact angle (CA) measurements to determine their wetting characteristics. Untreated aluminium is already weakly hydrophobic (water can partly stick to the surface, with a contact angle of 808). By coating it with a polymer, the contact angle was increased to 1108, making it hydrophobic. The superhydrophobic surface (CA = 1708) was produced by treating the aluminium in oxalic acid and then coating the rough 1369-7021/http://dx.doi.org/10.1016/j.mattod.2015.11.023
4