Narrow Results

Graphene, a two-dimensional nanomaterial reported for the first time in 2004, has been widely investigated for its novel physicochemical properties and potential applications. This review selectively summarizes the recent progress in using graphene-based nanomaterials for various biomedical applications. In particular, graphene-based sensors and biosensors, which are classified according to different sensing mechanisms and targets, are thoroughly discussed. Next, the utilization of graphene as nanocarriers for drug delivery, gene delivery and nanomedicine are demonstrated for potential cancer therapies. Finally, other graphene-based matrices, nanoscaffolds, and composites, which are used in bioapplications, are presented, followed by conclusions and perspective.

New techniques and materials are called for wastewater treatment due to the shortage of worldwide fresh water and the increasing water demand. As a simple and efficient method, adsorption technique has been extensively applied to remove organic and inorganic pollutants from contaminated water. The application of carbon nanomaterials, such as activated carbon, carbon nanotubes (CNTs), graphenes and their derivatives/analogues, in wastewater treatment has also been investigated due to their unique properties, such as wide availability, porous structure, large surface area, tunable morphology and nontoxicity. This review highlights the recent advances of wastewater treatment utilizing carbon nanomaterial modified composites as adsorbents. The adsorption phenomenon and its mechanism are briefly discussed. Detailed discussions are focused on the selective adsorption of carbon nanomaterial composites to unique pollutants. The remaining challenges are also mentioned.

Hybrid graphene oxide (GO) with metal ions have become very promising for many applications including catalyst, thermal conductive paper, magnetic devices, energy storage and electronics. In this paper, GO was mixed with trivalent rare earth ions, LaCl₃ to prepare GO/LaCl₃ hybrid composites. The GO/LaCl₃ hybrid composites were tunable by controlling the ratio of LaCl₃ to GO. The interaction between GO and LaCl₃ includes the coordination of La³⁺ with carboxyl groups at the edges of GO, the coordination of La³⁺ with epoxides and hydroxyls, and the electrostatic force between La³⁺ and aromatic bonds of GO. The La³⁺ preferred the coordination with the oxygen-containing groups of GO sheets first. However, the electrostatic absorption of La³⁺ was the main factor that controls the deposit of GO/LaCl₃ composites. The GO/LaCl₃ hybrid structures were also investigated.

Ovarian cancer is the highest mortality rate of all cancers in the female reproductive system. Over the past decades, small interfering RNA (si RNA) has been explored as a promising therapeutic candidate for gene therapy. However, its clinical application is limited by the lack of safe and efficient methods for gene delivery. Graphene oxide (GO) was modified with polyethylene glycol (PEG), polyethylenimine (PEI) and folic acid (FA), for targeted delivery of small interfering RNA (siRNA) that inhibits ovarian cancer cell growth, and the efficacy of such complex was evaluated by a series of in vitro experiments. The synthesized vehicle PEG-GO-PEI-FA was characterized by atomic force microscopy (AFM), Malvern particle size analyzer, UV-visible spectroscopy and Fourier transform infrared spectroscopy (FTIR), and the results showed that PEG, PEI and FA could be covalently grafted to GO surface, forming PEG-GO-PEI-FA particles with a size of $216.1\pm 2.457$nm and a potential of 14.7mV. Agarose-gel electrophoresis demonstrated that siRNA can be adsorbed onto the surface of PEG-GO-PEI-FA by electrostatic interaction. Laser confocal microscopy demonstrated that siRNA-adsorbed PEG-GO-PEI-FA could be target into folate receptor (FR)-overexpressing ovarian cancer cells. Compared to the PEG-GO-PEI/siRNA without folate modification, PEG-GO-PEI-FA/siRNA showed more pronounced inhibitory effect on growth of ovarian cancer cells. In conclusion, we have successfully synthesized a vector that is safe, efficient and specific to target tumor cell for gene delivery.

Photothermal therapy is a potential strategy to treat triple-negative breast cancer. The expression of HSP90 in the tumor cells has been identified as a culprit for reducing the effectiveness of photothermal therapy, so using reagents with photothermal conversion to deliver HSP inhibitors can achieve good tumor suppression. However, the potential toxicity of small molecule HSPs inhibitors limits their further application development. Therefore, this study constructed a nanoplatform by graphene oxide (GO) to deliver antisense oligonucleotide (ASO) of HSP90 to improve the therapeutic effect. The photothermal performance of GO was confirmed by infrared thermal imager. MTT results showed that tumor cell viability was lower after the addition of ASO under irradiation. In addition, the result of western blot revealed that the expression of HSP90 decreased by 32% compared to the blank group under the action of ASO. All the above results indicated that our strategy enhances the inhibition of triple-negative breast cancer cells via suppressing the expression of HSP90 in photothermal therapy.

This study describes an easy and cheap inkjet printing method for producing a paper-based gas sensor consisting of a composite film made of graphene oxide and poly(3,4-ethylenedioxythiophene) and poly(styrenesulfonate) (PEDOT:PSS). A glossy paper substrate is an inkjet printed with ink made by dispersing graphene oxide in a PEDOT:PSS conducting polymer solution to test its ability to detect ammonia (${\text{NH}}_3)$ at ambient temperature. The presence of few-layer graphene oxide in the PEDOT:PSS copolymer and the existence of $\pi$–$\pi$ interactions between graphene oxide and PEDOT:PSS are confirmed by Fourier transform infrared spectroscopy, UV–Visible spectrophotometer, and X-ray diffraction. In a small concentration range of 1–100 ppm at ambient temperature, the ink-jet printed graphene oxide-PEDOT:PSS gas sensor displays strong responsiveness and good selectivity to NH₃. The study found that ${\mathrm{\text{NH}}}_4$ is a strong donor in the ammonia gas produced by a bubble system of ammonia water, with ${\mathrm{\text{NH}}}_4$ molecules being ideal candidates for molecular doping of graphene. The ${\mathrm{\text{H}}}_2\mathrm{\text{O}}$ molecule can facilitate quick desorption by converting ${\mathrm{\text{NH}}}_3$ to ${\mathrm{\text{NH}}}_4$. The interaction between graphene oxide and ${\mathrm{\text{NH}}}_3$ molecules is weak. The attained gas-sensing performance may be attributed to the increased specific surface area of graphene oxide and enhanced interactions between the sensing film and ${\mathrm{\text{NH}}}_3$ molecules via $\pi$ and lone pair electron network. The ${\mathrm{\text{NH}}}_3$-sensing mechanisms of the flexible printed gas sensor are based on the competitive interaction of ammonia on the sensor, adsorption and dissociate ionization on the sensor surface.