Combinational portable raman probes: C-nanotubes for theranostics application

Abstract

Recently portable Raman probes have emerged into markets with a variety of applications including carbon nanotube (CNTs) characterization. Aqueous dispersed carbon nanotubes (CNTs) have shown a lot of promise towards biomedical application like drug / gene delivery vectors, photo-thermal therapy, and photoacoustic imaging. In this study we report the simultaneous detection and irradiation of carbon nanotubes in live cancer cells using a portable Raman probe. A portable handheld Raman instrument was utilized for dual purpose, as a CNT detector and as an irradiating laser source. Single walled carbon nanotubes (SWCNTs) and multiwalled carbon nanotubes (MWCNTs) were dispersed in an aqueous solution using a lipid-polymer (LP) coat which formed highly stable dispersions both in buffer and cell media. The LP coated SWCNTs and MWCNTs aqueous dispersions were characterized by atomic force microscopy, transmission electron microscopy, dynamic light scattering, Fourier transform infrared spectroscopy and Raman spectroscopy. The cellular uptake of the LP dispersed SWCNTs and MWCNTs was carried out using confocal microscopy, where the FITC labeled nanotube conjugates were found internalized by the breast cancer cells confirmed by Z-stack fluorescence confocal imaging. The in vitro biocompatibility of SWCNTs and MWCNTs, assessed using cell viability MTT assay, found that the nanotube dispersions did not hinder the cell proliferation of breast cancer cells at the dosages tested. Breast cancer cells treated with SWCNTs and MWCNTs were simultaneously detected and irradiated live in vitro using the portable Raman probe. Apoptotic TUNEL assay carried out on the breast cancer cells fixed after laser irradiation confirmed the cell death only in presence of the nanotube dispersions. For the first time we show that both SWCNTs and MWCNTs could be selectively irradiated by specifically detecting the CNTs in cancer cells using a simple handheld Raman instrument in three dimensionally grown cell culture. A combination of handheld Raman instrumentation used along with carbon nanomaterials could help treat various diseases like cancer.