Effects of antisense-myc-conjugated single-walled carbon nanotubes on HL-60 cells

Antisense therapy is limited in application in clinical therapy because of two existing problems: rapid degradation of antisense nucleic acids and poor diffusion across the cell membrane. Here we report the use of single-walled carbon nanotubes as delivery system for transporting antisense myc into HL-60 cells. Antisense-myc-conjugated single-walled carbon nanotubes were synthesized, characterized by atomic force microscopy (AFM), fluorescent microscopy, and Raman spectroscopy. Incubated with HL-60 cells at 37 degrees C, the single-walled carbon nanotubes (SWNTs) inside HL-60 cells were measured quantitatively by HPLC. Expression of c-myc gene and protein were analyzed by reverse transcriptase PCR and Western blot, respectively. Results showed that as-myc-conjugated SWNTs dropped character peaks at quadruple wavenumber (cm(-1)) compared with SWNTs, and could enter into HL-60 cells within 15 min after incubation, whose uptake amounts by HL-60 cells increased as the incubation time increased. After 48 hours, the amount of SWNTs in HL-60 cells began to decrease. Compared with as-myc and SWNTs, as-myc-conjuagted SWNTs exhibited the strongest inhibition on the proliferation of HL-60 cells, induced cell apoptosis, and down-regulated lowest expression of c-myc gene and C-MYC protein. The SWNTs can directly deliver as-myc into HL-60 cells, enhance the inhibition of as-myc on HL-60 cells, and is likely a better delivery system for antisense therapy. Antisense modified SWNTs can be used for intracellular gene regulation with potential applications in tumor therapy and drug delivery.