Research paperIn vivo behaviour of glyco-NaI@SWCNT ‘nanobottles’
Graphical abstract
Introduction
The inner cavities of carbon nanotubes (CNTs) can accommodate a wide range of guest species [1], [2], [3], [4]. Unprecedented structures and properties compared to those of the same material in the bulk can be observed when they are confined [5], [6], [7], [8], [9], [10], [11]. In the biomedical field, contrast agents and therapeutic compounds can be either attached to the external CNT walls or confined within the cavities of the CNTs [12], [13], [14], [15], [16], [17], [18]. The latter is attractive because CNTs can offer striking protection to chosen payloads, avoiding their interaction with the biological milieu [19].
Several strategies have been developed for the encapsulation of materials inside carbon nanotubes. Once filled, unless there is a strong interaction between the host nanotubes and the guest species, the ends of the CNTs need to be sealed/closed to allow selective purification from non-encapsulated materials left external to the CNT. Heating nanotubes together with inorganic salts at high temperatures allows capillary permeation of the melted salts inside the nanotubes with the spontaneous closure of the extremities during the cooling process [20], [21]. The salts remain stably confined in the form of ‘nanocrystals’ inside the nanotubes while leaving the outer surface essentially unaffected, and so ready to be modified by organic molecules.
As-produced, CNTs are insoluble in almost any aqueous solution and organic solvent, and have been suggested to be toxic to mammalian cells [22], thereby presenting perceived limitations to their biological applications [23], [24], [25], [26], [27]. Functionalization of CNT side-walls with biologically- and biotechnologically- relevant molecules (including polymers [28], peptides [29], [30], nucleic acids [31] and carbohydrates [32], [33]) allows the generation of potentially stable and biocompatible dispersions. For example, non-covalent binding of aromatic molecules by π–π stacking onto the surface of the nanotubes [34] or covalent modification of their polyarenic surface [35] allow loading of multiple molecules along the length of the nanotubes.
We have previously shown that encapsulation of radionuclide into the inner space of glycan-functionalized single-walled carbon nanotubes (glyco-X@SWCNT) may be achieved by molten filling and then covalent modification, allowing in vivo redirection of the distribution of the associated radioactivity from the thyroid to the lungs [33]. Here, we use steam-purified and shortened single-walled carbon nanotubes (SWCNTs) [36] filled with both ‘cold’ (NaI) and ‘hot’ (Na125I) cargoes and subsequent functionalization with different carbohydrates to explore the basis and role of glycan in this redistribution.
Section snippets
Purification of SWCNTs
Chemical vapour deposition (CVD) grown SWCNTs, were provided by Thomas Swan & Co. Ltd (Elicarb®). Steam purification was carried out in order to remove the amorphous carbon and graphitic shells formed during the synthesis [36]. Steam treatment was simultaneously employed to open the SWCNTs ends. For this purpose, 1 g of as-received SWCNTs were ground with agate mortar and pestle and then placed inside a tubular furnace. Steam was introduced by bubbling argon through hot water. The temperature
Preparation of ‘cold’ glyco-NaI@SWCNTs
To prepare the nanotubes for filling they were first treated with steam, followed by an HCl (aq) wash, in order to remove graphitic nanoparticles, amorphous carbon and metal catalysts that remain as impurities from their generation [36]. This method also results in simultaneous shortening of the nanotubes via a process believed to involve oxidation and decarboxylation of more reactive carbon sites present at their tips [36]. TEM images of both as-received and steam-purified SWCNTs are shown in
Conclusions
Functionalized and glycosylated nanotubes can act as ‘nanocapsules’ or ‘nanobottles’ to redirect the accumulation of inorganic radionuclide ‘cargo’ concealed in their inner void (here iodide) from a natural physiological target (here thyroid) [50] to alternative targets. At the functionalization loadings used here, different glycosylation patterns on these glyco-‘nanobottle’ constructs did not modulate in vivo distribution profiles. Instead, these appear to only aid dispersibility; these
Acknowledgements
This works was financially supported by EU FP7-ITN Marie-Curie Network programme RADDEL [grant number 290023] and the EU FP7-Integrated Infrastructure Initiative–I3 programme ESTEEM2 [grant number 312483]. We also acknowledge financial support from Spanish Ministry of Economy and Competitiveness through the “Severo Ochoa” Programme for Centres of Excellence in R&D [grant numbers SEV-2015-0496, ICMAB; SEV-2017-0706, ICN2]. The ICN2 is funded by the CERCA programme. We would like to thank Thomas
References (51)
- et al.
Mater. Sci. Eng. C
(2007) - et al.
Nat. Nanotechnol.
(2006) - et al.
Carbon
(2006) - et al.
Carbon
(2019) - et al.
Toxicol. Lett.
(2005) Eur. Polym. J.
(2005)- et al.
Sens. Actuator B-Chem.
(2007) - et al.
Carbon
(2018) - et al.
Chem
(2017) - et al.
J. Biol. Chem.
(2004)
Chem. Commun.
Sci. Technol. Adv. Mater.
ACS Nano
Science
Nat. Mater.
ChemistryOpen
ACS Nano
Adv. Mater.
Angew. Chem. Int. Edit.
ACS Nano
Small
Proc. Natl. Acad. Sci. USA
J. Nucl. Med.
Accounts Chem. Res.
Small
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