Highly surface functionalized carbon nano-onions for bright light bioimaging

Abstract

Carbon-based nanomaterials functionalized with fluorescent and water-soluble groups have emerged as platforms for biological imaging because of their low toxicity and ability to be internalized by cells. The development of imaging probes based on carbon nanomaterials for biomedical studies requires the understanding of their biological response as well as the efficient and safety exposition of the nanomaterial to the cell compartment where it is designed to operate. Here, we present a fluorescent probe based on surface functionalized carbon nano-onions (CNOs) for biological imaging. The modification of CNOs by chemical oxidation of the defects on the outer shell of these carbon nanoparticles results in an extensive surface functionalization with carboxyl groups. We have obtained fluorescently labelled CNOs by a reaction involving the amide bond formation between fluoresceinamine and the carboxylic acids groups on the surface of the CNOs. The functionalized CNOs display high emission properties and dispersability in water due to the presence of high surface coverage of carboxylic acid groups that translate in an efficient fluorescent probe for in vitro imaging of HeLa cells, without significant cytotoxicity. The resulting nanomaterial represents a promising platform for biological imaging applications due to the high dispersability in water, its efficient internalization by cancer cells and localization in specific cell compartments.

Toxicity Assessment of Carbon Nanomaterials in Zebrafish during Development

“…We investigated the effects induced by three different oxidized CNMs, schematically reported in Figure 1 , on zebrafish during development. The surface of pristine CNOs (p-CNOs) and pristine CNHs (p-CNHs) were decorated with carboxylic acid functionalities, following previously reported procedures [ 32 , 45 ], while GO was used as received.…”

“…The oxidation of p-CNOs was performed following the procedure reported in ref [ 32 ]. Briefly, 50 mg of p-CNOs were dispersed in 30 mL of 3 M nitric acid (HNO 3 ) by ultrasonication (20’ at 37 kHz) and stirred for 48 h. The oxi-CNOs were firstly centrifugated (15’ at 1800 rpm) to remove the excess of nitric acid and then filtered and washed with dH 2 O, DMF, methanol and acetone on a nylon filter membrane (pore size 0.2 μm) to recover 52 mg of oxi-CNOs.…”

“…CNOs are an attractive nanomaterials for imaging, diagnostic and therapeutic applications, due to their small size and spherical shape [ 28 ]. Our recent reports showed that surface functionalized CNOs presented low inflammatory potential [ 29 ], weak cytotoxicity in vitro, on different cell lines, including human breast adenocarcinoma cells (MCF-7 cells) [ 30 , 31 ], HeLa cells [ 32 , 33 , 34 , 35 ], HeLa Kyoto cells [ 36 ] and human cervix carcinoma cells, derivative of HeLa (KB cells) [ 33 ] and they were uptaken by cancer cells and accumulated in the lysosomes [ 31 , 33 , 35 ]. In addition, we probed that CNOs did not exert toxic effects in Hydra vulgari [ 37 ] and had high biocompatibility in zebrafish during the development [ 38 ].…”

Carbon Nanomaterials Interfacing with Neurons: An In vivo Perspective

“…On the opposite fullerenes, which attracted a lot of attention in the past, are now experiencing a gradual loss of interest due to concerns regarding toxicity (Zhu et al, 2006 ; Kolosnjaj et al, 2007 ; Partha and Conyers, 2009 ; Matija et al, 2013 ). Carbon nano-onions also are attracting attention for their possible biomedical application (Ghosh et al, 2011 ; Sonkar et al, 2012 ; Yang M. et al, 2013 ; Bartelmess et al, 2014 , 2015b , c ; Giordani et al, 2014 ; Frasconi et al, 2015a , b ). Notably, it has been demonstrated either in vitro and in vivo that carbon nanomaterials can be efficiently degraded by means of enzymatic catalytic oxidation processes that are occurring either in plants, prokaryotes and eukaryotes (Kotchey et al, 2012 , 2013 ; Bussy et al, 2015 ; Elgrabli et al, 2015 ; Sureshbabu et al, 2015 ) thus helping to dispel doubts regarding possible bioaccumulation hazards.…”

Recent advances in smart biotechnology: Hydrogels and nanocarriers for tailored bioactive molecules depot

“…Multi-shell fullerenes, known as carbon nano-onions (CNOs), have recently gathered great interest among researchers and have been successfully applied in a variety of different fields of application such as energy storage [243,244], catalysis [245], supercapacitors [246] and imaging [247].…”