Synthesis and use of a novel drug delivery particle, based on biocompatible polymer polyethylene glycol (PEG-400) and multi-walled carbon nanotubes (MWCNTs), is demonstrated in this work. MWCNTs with small length are less toxic than longer MWCNTs and single walled carbon nanotubes, as they are less likely to get accumulated inside body parts causing chronic inflammation. Studies focused on synthesis of MWCNTs of less than 1 µm are very few because the purity level of small MWCNTs is typically less. Instead, small nanotubes can be obtained by cutting long MWCNTs followed by segregation. Sonication is known for efficient dispersion and cutting of length of MWCNTs, but prolonged sonication results in damage of the nanotube walls and degradation of small nanotubes. Vigorous mechanical beating can break the MWCNTs without affecting the nanostructure. Hence prolonged vortex mixing aided by tungsten-carbide balls is used in this work for production of large quantities of small MWCNTs. Centrifugation is used to segregate MWCNTs of different lengths.

Addition of polyethylene glycol (PEG) could make CNTs bio-compatible, and therefore PEG has been used as both dispersion medium as well as segregation medium. Both small and medium length MWCNTs are found to be non-toxic to L929 -mouse fibroblast cells. In an attempt to produce less than 100 nm nanotubes in higher quantity, MWCNTs in PEG-400 were broken into small tubes using continuous vortex mixing for about 15 h. Separation of MWCNTs based on length was then carried out using rate-zonal centrifugation with various concentrations of PEG-400. The separated MWCNTs in PEG solution were further pelletized using high speed centrifugation and re-dispersed in water. Novel cocoon like oval nanoparticles of about 100–200 nm size was observed in one of the centrifuged fractions.

In the presence of MWCNTs, based on the dimension of the nanotubes, PEG molecular chains seem to self-assemble and form micro flakes around the nanotubes, resulting in nanostructures of definite shape, the phenomenon is not observed in the absence of MWCNTs.

Hydrophobic anti-cancer drug curcumin could be easily loaded into these cocoons. Both cocoon and cocoon-curcumin complex are hemocompatible and non-toxic to mice fibroblast (L929) cells. Curcumin with cocoons were successfully taken up by C6 glioma (rat brain cancer cells) while the same was not observed with curcumin alone. The novel nano cocoons developed in this work are nano-sized bio-compatible polymeric structures. These nano-cocoons demonstrate potential as carriers of drugs for different in vivo applications.