A method for the measurement of mass and number of graphene oxide sheets in suspension based on non-spherical approximations

Currently, particle analysis of 2D materials in suspension is commonly restricted to microscopic techniques in the dry state, and thus does not permit an accurate investigation of colloidal suspensions. Colloids in bulk can be assessed by light scattering and diffraction to investigate features such as their hydrodynamic size, charge and concentration. However, the main drawback of such techniques lies in the application of analytical and computational methods based on models assuming particle sphericity which are not representative for 2D materials. Resonance mass measurement (RMM) is a technique which can enable the analysis of 2D materials in suspension without the assumptions of spherical models. Here, we report the application of RMM to measure particle mass and concentration for three types of graphene oxide (GO) aqueous dispersions. Using micro- and nano-suspended resonating sensors, we were able to decipher gravimetric differences between GO and graphitic materials. Our results support the urge for proper definitions and standardisations of graphene based materials, and offer a new method of characterisation for 2D material colloids in liquid suspension

A method for the measurement of mass and number of graphene oxide sheets in suspension based on non-spherical approximations

From IOP Publishing via Jisc Publications RouterHistory: received 2021-01-11, revised 2021-04-26, oa-requested 2021-04-28, accepted 2021-05-04, epub 2021-06-02, open-access 2021-06-02, ppub 2021-07Publication status: PublishedFunder: Engineering and Physical Sciences Research Council; doi: http://dx.doi.org/10.13039/501100000266; Grant(s): GrapheneNOWNANO CDT; EP/L01548X/1Abstract: Currently, particle analysis of 2D materials in suspension is commonly restricted to microscopic techniques in the dry state, and thus does not permit an accurate investigation of colloidal suspensions. Colloids in bulk can be assessed by light scattering and diffraction to investigate features such as their hydrodynamic size, charge and concentration. However, the main drawback of such techniques lies in the application of analytical and computational methods based on models assuming particle sphericity which are not representative for 2D materials. Resonance mass measurement (RMM) is a technique which can enable the analysis of 2D materials in suspension without the assumptions of spherical models. Here, we report the application of RMM to measure particle mass and concentration for three types of graphene oxide (GO) aqueous dispersions. Using micro- and nano-suspended resonating sensors, we were able to decipher gravimetric differences between GO and graphitic materials. Our results support the urge for proper definitions and standardisations of graphene based materials, and offer a new method of characterisation for 2D material colloids in liquid suspension

Graphene oxide modulates dendritic cell ability to promote T cell activation and cytokine production

An important aspect of immunotherapy is the ability of dendritic cells (DCs) to prime T cell immunity, an approach that has yielded promising results in some early phase clinical trials. However, novel approaches are required to improve DC therapeutic efficacy by enhancing their uptake of, and activation by, disease relevant antigens. The carbon nano-material graphene oxide (GO) may provide a unique way to deliver antigen to innate immune cells and modify their ability to initiate effective adaptive immune responses. We have assessed whether GO of various lateral sizes affects DC activation and function in vitro and in vivo, including their ability to take up, process and present the well-defined model antigen ovalbumin (OVA). We have found that GO flakes are internalised by DCs, while having minimal effect on their viability, activation phenotype or cytokine production. Although adsorption of OVA protein to either small or large GO flakes promoted its uptake into DCs, large GO interfered with OVA processing. In terms of modulation of DC function, delivery of OVA via small GO flakes significantly enhanced DC ability to induce proliferation of OVA-specific CD4 T cells, promoting granzyme B secretion in vitro. On the other hand, delivery of OVA via large GO flakes augmented DC ability to induce proliferation of OVA-specific CD8 T cells, and their production of IFN-γ and granzyme B. Together, these data demonstrate the capacity of GO of different lateral dimensions to act as a promising delivery platform for DC modulation of distinct facets of the adaptive immune response, information that could be exploited for future development of targeted immunotherapies.his work was supported by the Engineering and Physical Sciences Research Council (EPSRC) under the 2D-Health Programme Grant [EP/P00119X/1]. The Nanomedicine Group at ICN2 is partially supported by the CERCA programme, Generalitat de Catalunya, and the Severo Ochoa Centres of Excellence programme, funded by the Spanish Research Agency (AEI, grant no. SEV-2017-0706)